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Applied insect ecology, evolution, insect behavior, and integrated pest management.
Applied insect ecology, evolution, insect behavior, and integrated pest management.
Presently, humans posses a vast arsenal of different pest control techniques, ranging from synthetic insecticides to natural enemies, and from transgenic plants to quarantine regulations. What is lacking, however, is a good understanding of the ecological consequences of their implementation for both target and non-target organisms. When a particular action is taken, whether it is an insecticide application, planting of a transgenic cultivar, or release of a biological control agent, it is imperative that we can forecast the sequence(s) of events it might trigger. Limited-scale toxicological and host-range assays, still commonly used for decision-making, often do not reflect actual developments in the field. Therefore, a more sophisticated approach, which takes into account an intricate web of cause-and-effect events within a given ecosystem, is required to achieve a long-term success both in pest control, as well as in conservation of beneficial organisms. Most ecological systems are very complex, and their good understanding is extremely difficult. However, sustainable development of the human civilization is hardly possible without such an understanding. As a scientist, I hope that my research will contribute to building a knowledge-based foundation for predicting effects of human intervention in insect communities. I am also interested in more theoretical investigations of factors responsible for growth and diversity of insect populations.
Chen, J., A. Alyokhin, D. Mota-Sanchez, M. Baker and M. Whalon. 2014. Variation in fitness among geographically isolated Colorado potato beetle (Coleoptera: Chrysomelidae) populations. Annals of the Entomological Society of America 107: 128-135.
Alyokhin, A. 2011. Scant evidence supports EPA's pyramided Bt corn refuge size of 5%. Nature Biotechnology 29: 577–578.
Alyokhin, A. 2011. Non-natives: put biodiversity at risk. Nature 475: 36.
Alyokhin, A., F. A. Drummond, G. Sewell, and R. H. Storch. 2011. Differential effects of weather and natural enemies on coexisting aphid populations. Environmental Entomology 40: 570-580.
Alyokhin, A., J. Makatiani, and K. Takasu. 2010. Insecticide odour interference with food-searching behaviour of Microplitis croceipes (Hymenoptera: Braconidae) in a laboratory arena. Biocontrol Science and Technology 20: 317-329.
Finlayson, C. J., A. V. Alyokhin, and E. W. Porter. 2009. Interactions of native and non-native lady beetle species (Coleoptera: Coccinellidae) with aphid-tending ants in laboratory arenas. Environmental Entomology 38: 846-855.
Alyokhin, A., M. Baker, D. Mota-Sanchez, G. Dively, and E. Grafius. 2008. Colorado potato beetle resistance to insecticides. American Journal of Potato Research 85: 395–413. (Invited review article).
Physiological, molecular, and field studies of fungal pathogens of plants and animals
Physiological, molecular, and field studies of fungal pathogens of plants and animals
My research focuses on fungi that are pathogens of plants and animals. Research projects in my laboratory examine the genetic diversity, physiology and molecular biology of various fungal pathogens and applied aspects of control of fungi that attack lowbush blueberry. A major focus of my research is mummy berry disease caused by Monilinia vaccinii-corymbosi and a disease identified in Maine for the first time in 2009, Valdensinia leaf spot, caused by Valdensinia heterodoxa. Current research interests include evaluating the genetic diversity of M. vaccinii-corymbosi in lowbush blueberry, determining the genetic relatedness of lowbush blueberry clones that differ in their levels of mummy berry disease severity, examining the mode of infection of M. vaccinii-corymbosi and V. heterodoxa, and determining the major methods of spread of Valdensinia leaf spot. Laboratory personnel are also involved in evaluating lower risk and organic materials and management techniques to control disease and providing information on the use of forecasting methods to improve effectiveness of disease control.
Drummond, F., S. Annis, J. M. Smagula and D.E. Yarborough. 2009. Organic Production of Wild Blueberries. I. Insects and Disease. Acta Horticulturae 810: 275-286.
Smagula, J.M., D.E. Yarborough, F.A. Drummond, and S. Annis. 2009. Organic Production of Wild Blueberries II. Fertility and Weed Management. Acta Horticulturae 810: 673-684.
Yarborough, D.E., J.M. Smagula, F.A. Drummond, and S. Annis. 2009. Organic Production of Wild Blueberries III. Fruit Quality. Acta Horticulturae 810: 847-852.
Penman, L. N. and Annis, S. L. 2005. Variation of mummy berry blight in clones of lowbush blueberry: effects on yield and relationship to bud phenology. Phytopathology 95:1174-1182.
Annis, S.L. and C.S. Stubbs. 2004. Stem and leaf diseases and their effects on yield in Maine lowbush blueberry fields. Small Fruits Review 3(1/2):159-167.
Piotrowski, J.S., S.L. Annis, and J.E. Longcore. 2004. Physiology of Batrachochytrium dendrobatidis, a chytrid pathogen of amphibians. Mycologia 96:9-15.
Annis, S.L., Dastoor, F., Ziel, H., Daszak, P., Longcore, J.E. 2004. A DNA-based assay to identify Batrachochytrium dendrobatidis in amphibians. Journal of Wildlife Diseases 40(3): 420-428.
H. Xu, S. Annis, J. Linz, and F. Trail. 2000. Infection and colonization of peanut pods by Aspergillus parasiticus and the expression of aflatoxin biosynthetic genes in infection hyphae. Physiological and Molecular Plant Pathology 56:185-196.
S. Annis, L. Velasquez, H. Xu, R. Hammerschmidt, J. Linz, and F. Trail. 2000. Novel procedure for identification of compounds inhibitory to transcription of genes involved in mycotoxin biosynthesis. Journal of Agricultural and Food Chemistry 48:4656-4660.
Cellular, biochemical, and molecular analysis of the actin cytoskeleton in response to renal ischemia.
Cellular, biochemical, and molecular analysis of the actin cytoskeleton in response to renal ischemia.
My research focuses on the response of the actin cytoskeleton to ischemia induced acute renal failure (ARF). ARF occurs at a high frequency in the American adult population with the nation-wide cost for patient care estimated at over twelve billion dollars a year. Although the occurrence of ARF is high and leads to significant mortality rates, very little progress has been made in the last thirty years to overcome these statistics. In addition, very expensive medical procedures such as long term dialysis or renal transplantation often follow an occurrence of ARF. Ischemic ARF is characterized by reduced blood flow to the kidney that results in cell injury and inflammation that leads to decreased urine production and increased toxic end products in the circulating blood. Reorganization of the actin cytoskeleton in kidney proximal tubule cells is one of the earliest observable signs of ischemia induced kidney cell injury. The bundled actin filaments present in the apical microvilli of these cells are severed and depolymerized and actin dependent cellular polarization is lost as well as cell-to-cell and cell-to-substrate adhesion. The extent of damage to these cellular structures depends on the severity and length of the ischemic event. To understand better the actin cytoskeletal changes observed in response to ARF, my laboratory is investigating the interaction of actin with two competing actin binding proteins, cofilin (an actin severing and depolymerizing protein) and tropomyosin (an actin stabilizing protein). We are using immunofluorescence and confocal microscopy to visualize these changes in cell culture, rat, and mouse kidneys and in the zebrafish pronephros. To analyze regulation of these two proteins, cofilin and tropomyosin, we are using molecular and biochemical techniques under physiologic and ischemic conditions. A better understanding of how ischemic insults affect the actin cytoskeleton in kidney cells will lead to new treatment methods and improved survival rates for patients suffering from acute renal failure.
Marquis H, Bell EP, Miller EE, Gilman MS, Bond SK, Grimaldi R, Ashworth SL. 2009. Analysis of the Danio rerio cofilin mutant. MDIBL Bulletin: 48, 52-53.
Campos SB, Ashworth SL, Hosford M, Sandoval RM, Hallett MA, Atkinson SJ, Molitoris BA. 2009. Cytokine induced F-actin reorganization in endothelial cells involves RhoA activation. American Journal of Physiology- Renal Physiology: 296, F487-F495.
Ashworth SL, Sandoval RM, Tanner GA, Molitoris BA. 2007. Two-photon Microscopy: Visualization of Kidney Dynamics. Kidney International: 72, 416-421.
Ashworth SL and Tanner GL. 2006. Fluorescent labeling of renal cells in vivo. Nephron: 103, 91-96.
Suurna MV, Ashworth SL, Hosford M, Sandoval RM, Wean SE, Shah BM, Bamburg JR, Molitoris BA. 2006. Cofilin mediates ATP Depletion-induced endothelial cell actin alternations. American Journal of Physiology- Renal Physiology: 290, F1398-1407.
Tanner GA., Sandoval RM, Molitoris BA, Bamburg JR, Ashworth SL. 2005. Micropuncture gene delivery and intravital two-photon visualization of protein expression in rat kidney. American Journal of Physiology- Renal Physiology: 289(3), F638-643.
Ashworth SL, Wean SE, Campos SB, Temm-Grove CJ, Southgate EL, Vrhovski B, Gunning P, Weinberger RP and Molitoris BA. 2004. Renal ischemia induces tropomyosin dissociation-destabilizing microvilli microfilaments. American Journal of Physiology- Renal Physiology: 286, F988-F996.
Ashworth SL, Southgate EL, Sandoval RM, Meberg PJ, Bamburg JR, Molitoris BA. 2003. ADF/Cofilin mediates actin cytoskeleton alterations in LLC-PK cells during ATP depletion. American Journal of Physiology- Renal Physiology: 284, F852-F862.
Biogeochemistry; plant ecology; ecosystem ecology; land use planning
Biogeochemistry; plant ecology; ecosystem ecology; land use planning
My research focuses on ecosystem-level biogeochemistry, forest ecology, and watershed analysis. Specific interests include element cycling patterns and processes, comparative soil chemistry in forest ecosystems, linkages between terrestrial and aquatic ecosystems, organic matter cycling and decomposition, chemistry and role of humic acids in forest ecosystems, land-use effects on water quality in large river systems, effects of air pollution, acidic deposition on forested watersheds, carbon cycling, and global change.
Parr, T.B, C.S. Cronan, T. Ohno, S.E.G. Findlay, S.M.C. Smith, and K.S. Simon. 2015. Urbanization changes the composition and bioavailability of DOM in headwater streams. Limnology & Oceanography: in press.
Meyer, S.R., M.L. Johnson, R.J. Lilieholm, and C.S. Cronan. 2014. Development of a stakeholder-driven spatial modeling framework for strategic landscape planning using Bayesian networks across two urban-rural gradients in Maine, USA. Ecological Modelling 291:42-57.
Meyer, S.R., C.S. Cronan, R.J. Lilieholm, M.L. Johnson, and D.R. Foster. 2014. Land conservation in northern New England: historic trends and alternative conservation futures. Biological Conservation 174: 152-160.
Lilieholm, R.J., S.R. Meyer, M.L. Johnson, and C.S. Cronan. 2013. Land conservation in the Northeastern United States: an assessment of historical trends and current conditions. Environment: 55(4):3-14.
Cronan, C.S. 2012. Biogeochemistry of the Penobscot River Watershed, Maine, USA: Nutrient Export Patterns for Carbon, Nitrogen, and Phosphorus. Environmental Monitoring and Assessment 184: 4279-4288.
Cronan, C.S., R.J. Lilieholm, J. Tremblay, and T. Glidden. 2010. An assessment of land conservation patterns in Maine based on spatial analysis of ecological and socioeconomic indicators. Environmental Management 45: 1076-1095.
Cronan, C.S. 2008. Ecosystem Biogeochemistry – Element Cycling in the Forest Landscape. Shaw-Ferguson Environmental Publications. 265 p.
Driscoll, C., D. Whitall, J. Aber, E. Boyer, M. Castro, C. Cronan, C. Goodale, P. Groffman, C. Hopkinson, K., Lambert, G. Lawrence, and S. Ollinger. 2003. Nitrogen pollution in the northeastern United States: sources, effects, and management options. BioScience 53: 357-374.
Cronan, C.S. 2003. Belowground biomass, production, and carbon cycling in mature Norway spruce, Maine, USA. Canadian Journal of Forest Research 33: 339-350.
Driscoll, C.T., G. Lawrence, A. Bulger, T. Butler, C. S. Cronan, C. Eager, K. F. Lambert, G.E. Likens, J. Stoddard, and K. Weathers. 2001. Acidic deposition in the Northeastern U.S.: sources and inputs, ecosystem effects, and management strategies. BioScience 51: 180-198.
Cronan, C.S., J.T. Piampiano, and H.H. Patterson. 1999. Influence of land use and hydrology on exports of carbon and nitrogen in a Maine river basin. Journal of Environmental Quality 28: 953-961.
Cronan, C.S. 1996. Introduction to Ecology and Ecosystems Analysis. Shaw-Ferguson Environmental Publications. 256 p.
Cronan, C.S. and D.F. Grigal. 1995. Use of Ca/Al ratios as indicators of stress in forest ecosystems. Journal of Environmental Quality 24:209-226.
Cronan, C.S. 1991. Differential adsorption of Al, Ca, and Mg by roots of red spruce (Picea rubens Sarg.). Tree Physiology 8:227-237.
Cronan, C.S. and C.L. Schofield. 1990. Relationships between aqueous aluminum and acidic deposition in forested watersheds of North America and northern Europe. Environmental Science and Technology 24:1100-1105.
Expanded List of Publications
Large class pedagogy and instructional best practices; Ecology of microbe/bird interactions
Large class pedagogy and instructional best practices; Ecology of microbe/bird interactions
Functional and comparative genomics of low temperature stress tolerance in plants; genetic network modeling; stress response signaling
Functional and comparative genomics of low temperature stress tolerance in plants; genetic network modeling; stress response signaling
The multi-faceted defenses of plants against the physiological perturbations caused by environmental extremes are configured by integrative functioning of a large number of genes operating through a highly coordinated regulatory network. Under this level of complexity, expressing the full stress tolerance potential of a plant requires intricate regulation of the transcriptome and proteome. An international collaborative research led by Benildo de los Reyes of the School of Biology and Ecology has a major goal of: 1) Understanding the hierarchical organization of stress response regulatory networks and how such network of genes configure the physiological and biochemical defenses at the cellular and whole-plant levels; and 2) Understanding the genetic changes that gave rise to a gradient of stress response network complexity during speciation and domestication.
The De los Reyes Lab and its collaborators make use of rice (Oryza sativa) and thale cress (Arabidopsis thaliana) as reference species to conduct genome-enabled investigations facilitated by state of the art tools of physiology and biochemistry, transcriptomics (microarray, mRNA-Seq, miRNA-Seq), bioinformatics (cis-regulatory information analysis and network modeling), and phenomics (transgenic analysis). Current projects include: 1) Comparative analysis orthologous OsMyb4 and OsTGA10 regulons among syntenic and non-syntenic monocot (Oryza, Sorghum, Brachypodium) and dicot (Arabidopsis, Solanum) genomes; 2) Analysis of stress (abiotic and biotic) response network complexities that evolved during a narrowly spaced (15 million years) speciation and domestication events in the genus Oryza; and 3) Understanding the cross-talks between insect and disease response signaling in tuber-bearing Solanum species.
Park MR, Baek S-H, De los Reyes BG, Yun SJ, Hasenstein KH (2011) Transcriptome profiling characterizes phosphate deficiency effects on carbohydrate metabolism in rice leaves. Journal of Plant Physiology (In Press; JPLPH-51339).
Rioux R, Manmathan H, Jia Y, De los Reyes BG, Tavantzis S (2011). Comparative analysis of putative pathogenesis-related gene expression in two Rhizoctonia solani pathosystems. Current Genetics (In press; DOI: 10.1007/s00294-011-0353-3).
Park MR, Yun KY, Herath V, Mohanty B, Xu F, Bajic VB, Yun SJ, De los Reyes BG (2010) Supra-optimal expression of the cold-regulated OsMyb4 transcription factor in transgenic rice changes the complexity of transcriptional network with major effects on stress tolerance and panicle development. Plant, Cell and Environment 33:2209-2230.
Yun KY, Park MR, Mohanty B, Herath V, Xu F, Mauleon R, Wijaya E, Bajic VB, Bruskiewich R, De los Reyes BG (2010) Transcriptional regulatory network triggered by oxidative signals configures the early response mechanisms of japonica rice to chilling stress. BMC Plant Biology 10:e16. [HIGHLY ACCESSED]
Zhang Y, Xuan J, De los Reyes BG, Clarke R, Ressom HW (2009) Reverse engineering module networks by PSO-RNN hybrid modeling. BMC Genomics 10 (Suppl):S15.
Ressom HW, Lakshman D, Yun SJ, Pramanik SK, De los Reyes BG (2009) Microarray data analysis using machine learning methods. In: Biosystems Engineering, A. Nag (editor), McGraw Hill Pub., pp. 1-32.
Zhang Y, Xuan J, De los Reyes BG, Clarke R, Ressom HW (2008) Identification of network motifs for transcription factors by integrating multi-source biological data. BMC Bioinformatics 9:e203. [HIGHLY ACCESSED]
De los Reyes BG, Lakshman D, Yun SJ, Ressom H (2008) Agricultural genomics. In: Agricultural Biotechnology, A. Nag (editor), PHI Learning Private Ltd., pp. 55-88.
McGrath JM, Elawady A, El-Khishin D, Naegele RP, Carr KM, De los Reyes BG (2008) Sugar beet germination: Phenotypic selection and molecular profiling to identify genes involved in abiotic stress response. Acta Horticulturae 782:35-48.
Irish BM, Corell JM, Feng C, Bentley T, De los Reyes BG (2007) Characterization of a resistance locus (Pfs-1) to the spinach downy mildew pathogen (Peronospora farinosa f. sp. spinaciae) and development and evaluation of a co-dominant molecular marker linked to Pfs1. Phytopathology 98:894-900.
Cheng C, Yun KY, Ressom H, Mohanty B, Bajic VB, Jia Y, Yun SJ, De los Reyes BG (2007) An early response regulatory cluster induced by low temperature and hydrogen peroxide in seedlings of chilling-tolerant japonica rice. BMC Genomics 8:e175.
Park MR, Baek SH, De los Reyes BG, Yun SJ (2007) Overexpression of a high-affinity transporter gene from tobacco (NtPT1) enhances phosphate uptake and accumulation in transgenic rice plants. Plant and Soil 292:259-269.
Ballou S, Yun KY, Cheng C, De los Reyes BG (2007) Cold sensitivity gradient in tuber-bearing Solanum based on physiological and transcript profiles. Crop Science 47:2027-2035.
Antoine W, Stewart JM, De los Reyes BG (2005) The rice homolog of the sodium/lithium tolerance (SLT1) gene functions as molecular chaperone in vitro. Physiologia Plantarum 125: 299-310.
Insect quantitative ecology, pest management, population dynamics, simulation modeling, biostatistics, pollination ecology
Insect quantitative ecology, pest management, population dynamics, simulation modeling, biostatistics, pollination ecology
My research interests are in insect epizootiology, pollination ecology, and integrated pest management of blueberry pests in Maine. Currently, my research interests are as follows: development of stage-structured simulation models to elucidate the spatial and temporal dynamics of disease epizootiology in insect populations, development of multi-time step numerical methods for solving cascaded differential equations with an Erlang output distribution, comparative foraging behavior of bees visiting lowbush blueberry, conservation of native bees, effects of weediness on beneficial insects associated with blueberry ecosystems, microbial control of blueberry insect pests, and development of economic threshold models for pest management decision making.
Smagula, J.M., D.E. Yarborough, F.A. Drummond, and S. Annis. 2009. Organic Production of Wild Blueberries II. Fertility and Weed Management. Acta Horticulturae 810: 673-684.
Yarborough, D.E., J.M. Smagula, F.A. Drummond, and S. Annis. 2009. Organic Production of Wild Blueberries III. Fruit Quality. Acta Horticulturae 810: 847-852.
Peshlov, B.N., F.E. Dowell, F.A. Drummond, and D.W. Donahue. 2009. Comparison of three NIR spectrophotometers for infestation detection in wild blueberries using multivariate calibration models. Journal of NIR Spectroscopy 17: 203-212.
Arevalo, H.A., J. Collins, E. Groden, F. Drummond, K. Simon. 2009. Marking blueberry maggot flies (Diptera: Tephritidae) using fluorescent diet for recapture studies. Florida Entomologist 92(2): 379-381.
Drummond, F., S. Annis, J. M. Smagula and D.E. Yarborough. 2009. Organic Production of Wild Blueberries. I. Insects and Disease. Acta Horticulturae 810: 275-286.
Samson, P.R., K.J. Chandler, M.N. Sallam, and F.A. Drummond. 2009. A proposed monitoring system for greyback canegrub, Dermolepida albohirtum, to aid growers' management decisions. Australia Society of Sugarcane Technologists 29: 91-93.
Griffin, T., G. Anderson, F. Drummond, E. Groden, W. Honeycutt, J. Jemison, L. Stack, and D. Yarborough. 2009. Agriculture, pp 39-42. In: Maine's Climate Future: An Initial Assessment (G. Jacobson, I.J. Fernandez, P.A. Mayewski, and C.V. Schmitt, editors). University of Maine, Orono, ME. 70 pp.
Bell, D.J., L.J. Rowland, J. Smagula, and F.A. Drummond. 2009. Recent Advances in the Biology and Genetics of Lowbush Blueberry. Maine Agriculture Forest Experiment Station, University of Maine, Orono. Technical Bulletin 36 pp.
Welch A., Drummond, F.A., Tewari, S., Averill, A., and J. P. Burand. 2009. Presence and prevalence of viruses in local and migratory honeybees (Apis mellifera) in Massachusetts. Applied and Environmental Microbiology 75(24): 7862-7865.
Karem, J., F.A. Drummond, S.A. Woods, and C. Stubbs. 2010. The relationships between Apocrita wasp populations and flowering plants in Maine's wild lowbush blueberry agroecosystems. Journal of Biocontrol Science and Technology 20 (3): 257-274.
Bell, D.J., L.J. Rowland, D. Zhang, and F.A. Drummond. 2009. Spatial genetic structure of lowbush blueberry, Vaccinium angustifolium, in four fields in Maine. Botany 87: 932-946.
Horsfield, A., M. N. Sallam, and F.A. Drummond. 2008. Role of climatic factors on damage incidence by greyback canegrub, Dermolepida albohirtum (Waterhouse) (Coleoptera: Scarabaeidae), in Burdekin sugarcane fields, Australia. Journal of Economic Entomology 101(2): 334-340.
Bell, D.J., L.J. Rowland, J.J. Polashock, and F.A. Drummond. 2008. Suitability of EST-PCR markers developed in highbush blueberry for genetic fingerprinting and relationship studies in lowbush blueberry and related species. Journal of American Society of Horticultural Science 133: 631-722.
Aquatic toxicology, biochemical biomarkers of exposure and effect, development of chemical tolerance, fish health, non-lethal approaches, endangered species, early life stage effects
Aquatic toxicology, biochemical biomarkers of exposure and effect, development of chemical tolerance, fish health, non-lethal approaches, endangered species, early life stage effects
My research focuses on the response of aquatic organisms to pollutants, including metals, fuel oil, organochlorines, and pesticides. In these investigations I examine the consequences of pollutant exposure to organism health, particularly to physiological processes, reproduction, early life stage development, biochemical metabolism and the development of tolerance to chemicals. I conduct my research within an ecological context to determine how season, gender, life history, and habitat affect organism response. My work involves aspects of both field and laboratory research, requires whole animal, biochemical and molecular manipulations, and is supported by chemical analysis. Current projects include the effects of multiple stressors on survival, reproduction, and physiological processes in aquatic organisms, and the development of non-lethal approaches for assessing exposure and response to pollutants by endangered species.
Brammell, B.F., Price, D.J., Birge, and Elskus, A.A. 2013. Lack of CYP1A responsiveness in species inhabiting chronically contaminated habitats: two varieties of resistance? Comparative Biochemistry & Physiology 157(2):212-9. doi: 10.1016/j.cbpc.2012.07.001.
Elskus, A.A., 2012. Toxicity, Sub-lethal Effects and Potential Modes of Action of Select Fungicides on Freshwater Fish and Invertebrates. U.S. Geological Survey Open-File Report 2012-1213 v.1.1, 42 p. at http://pubs.usgs.gov/of/2012/1213/.
Loftin, C.S., Calhoun, A.J.K., Nelson, S.J., Elskus, A.A., Simon, K. 2012. Mercury bioaccumulation in wood frogs developing in seasonal pools. Northeastern Naturalist 19(4):579-600.
Elskus, A.A. Assessment of Environmental Conditions on the Penobscot River (Maine) Prior to Dam Removal: Characterization of Contaminants in Fish and Bivalves. Surface Water Ambient Toxics Monitoring Program 2012 FINAL REPORT. Maine Department of Environmental Protection. March 2013, pp. 136-148. http://www.maine.gov/dep/water/monitoring/toxics/swat/2012/2012-SWAT-report.pdf.
Elskus, A.A., van Beneden R, Perkins, L.B., Gosse, J., Ashworth, S, Skall, DG. 2011. Fish Scales as Non-Lethal Biosensors of Surface Water Contaminants. FINAL REPORT. To: The George Mitchell Center for the Environment, Maine Water Resources and Research Institute. USGS104b Grant 01HQGR0083. National Institute of Water Resources. 4 May 2011. http://water.usgs.gov/wrri/10grants/2010ME214B.html.
Brammel, B.F., Price, D.J., Birge, W.J., Laws E.M., Hitron, J.A., and Elskus, A.A. (2010) Differential sensitivity of CYP1A to 3,3',4,4'-tetrachlorobiphenyl and benzo(a)pyrene in two Lepomis species. Comparative Biochemistry and Physiology Part C. Toxicology 152:42-50.
Arzuaga, X., and Elskus, A.A. (2010) Polluted site killifish (Fundulus heteroclitus) embryos are resistant to organic pollutant-mediated induction of CYP1A activity, reactive oxygen species and heart deformities. Environmental Toxicology and Chemistry 29:676-682.
Brammell, B.F., McClain, J.S., Oris, J.T., Price, D.J., Birge, W.J., and Elskus, A.A. (2010) CYP1A expression in caged rainbow trout discriminates among sites with various degrees of PCB contamination. Archives of Environmental Contamination and Toxicology 58:772-782.
Holliday, D.K., Elskus, A.A., Roosenburg, W.M. (2009) Impacts of multiple stressors on growth and metabolic rate of Malaclemys terrapin. Environmental Toxicology and Chemistry 28(2): 338-345.
Holliday, D.K., Roosenburg, W.M., Elskus, A.A. (2008) Spatial variation in polycyclic aromatic hydrocarbon concentrations in eggs of diamondback terrapins, Malaclemys terrapin, from the Patuxent River, Maryland. Bulletin of Environment Contamination and Toxicology 80(2):119-122.
Elskus, A.A., 2007, Pilot study of sublethal effects on fish of pesticides currently used and proposed for use on Maine blueberries: U.S. Geological Survey Open-File Report 2007-1110. April 2007. 10 pp.
Arzuaga, X., Wassenburg, D., Di Giulio, R., Elskus, A.A. (2006) The chlorinated AHR ligand 3,3',4,4',5-pentachlorobiphenyl (PCB126) promotes reactive oxygen species (ROS) production during embryonic development in the killifish (Fundulus heteroclitus). Aquatic Toxicology 76(1):13-23.
Elskus, A.A., Collier, T.K., Monosson, E. (2005) Chapter 4. Interactions between lipids and persistent organic pollutants in fish. In: Biochemistry and Molecular Biology of Fishes, Volume 6. Environmental Toxicology. T.P. Mommsen and T.W. Moon, Eds. Elsevier Science, St. Louis. pp. 119-152.
paleoecology, community ecology, vegetation dynamics, extinction, climate change, biotic interactions
paleoecology, community ecology, vegetation dynamics, extinction, climate change, biotic interactions
I am a paleoecologist and biogeographer, bringing the perspectives of space and time to bear on questions in ecology and global change science. My work takes a community ecology approach to help understand how species and their interactions have responded to interacting drivers (like climate change and extinction) through time. I'm especially interested 1) novel communities and ecosystems 2) the legacies "biotic upheavals" like the extinction of Pleistocene megafauna, 3) biotic drivers of landscape change on long (>1,000 years) timescales (e.g., herbivory, dispersal, insect outbreaks), and 5) what the paleorecord tells us about the ability of plants to migrate in response to climate change.
Gill, J. L., J. W. Williams, S. T. Jackson, K. B. Lininger, G. S. Robinson. (2009). Pleistocene megafaunal collapse, novel plant communities, and enhanced fire regimes in North America. Science 326(5956): 1100-1103. [Supplemental online material] See also the accompanying Perspectives article by Chris Johnson and listen to the Science podcast interview. Gill, J. L., J. W. Williams, S. T. Jackson, J. P. Donnely, G. C. Schellinger. (2012). Climatic and megaherbivory controls on late-glacial vegetation dynamics: A new, high-resolution multi-proxy record from Silver Lake, OH. Quaternary Science Reviews 34: 66-80. Schwartz, M. W. , J. J. Hellmann, J. M. McLachlan, D. F. Sax, J. O. Borevitz, J. Brennan, A. E. Camacho, G. Ceballos, H. Doremus, R. Early, J. R. Etterson, J. L. Gill, P. Gonzalez, N. Green, L. Hannah, D. W. Jamieson, D. Javeline, B. A. Minteer, J. Odenbaugh, S. Polasky, D. M. Richardson, T. L. Root, H. D. Safford, O. Sala, S. H. Schneider, A. R. Thompson, J. W. Williams, M. Velland, P. Vitt, S. Zellmer. (2012). Managed relocation: integrating the scientific, regulatory, and ethical challenges. Bioscience 62 (8): 747-743. Gill, J. L., K. K. McLauchlan, A. M. Skibbe, S. J. Goring, John W. Williams. (2013). Linking abundances of the dung fungus Sporormiella to the density of American bison (Bison bison): implications for assessing grazing by megaherbivores in the paleorecord. Journal of Ecology 101(5): 1125-1136. Gill, J. L. (2014). The ecological legacy of the late Quaternary extinctions of megaherbivores. New Phytologist 201 (4): 1163-1169. Seddon, A. W. R., A. Baker, A. W. Mackay, E. E. Ellis, L. Gillson, E. Johnson, S. Juggins, K. Willis, C. Buck, C. A. Froyd, V. Jones, M. Macias-Fauria, D. Nogues-Bravo, S. Punyasena, E. Breman, J. L. Gill, K. Mills, J. Morris, A. Tanentzap, T. Roland, and the Palaeo50 Working Group. (2014). Looking forward through the past: identification of 50 priority research questions in palaeoecology. Journal of Ecology 102 (1): 256-267.
Community ecology, environmental gradients, global change; aquatic ecology, freshwater invertebrates
Community ecology, environmental gradients, global change; aquatic ecology, freshwater invertebrates
My research uses freshwater ecosystems to understand how environmental gradients influence community structure and function. Specifically, my research focuses on three key questions: 1) How do disturbances influence community structure and dynamics? 2) How do local stresses modify the effects of global change on ecosystems? 3) What are the mechanisms underlying the effects of temperature changes on food webs? I approach these questions by using combination of observational studies, field manipulations, and mesocosm experiments to test hypotheses across spatial scales and levels of ecological complexity. My work is motivated by the view that revealing the mechanisms behind the environmental context of ecological processes is the key to developing the general understanding necessary to manage human impacts on ecosystems.
Atwood, T. B., E. Hammill, H. S. Greig, P. Kratina, J. B. Shurin, D. S. Srivastava and J. S. Richardson. 2013. Predators reduce CO2 emissions from freshwater ecosystems. Nature Geoscience. 6: 191-194. doi:10.1038/ngeo1734.
Greig, H. S., S. A. Wissinger, and A. R. McIntosh. 2013. Top-down control of prey biomass increases with drying disturbance: an unexpected consequence of non-consumptive interactions? Journal of Animal Ecology. doi: 10.1111/1365-2656.12042.
Shurin, J. B., J. Clasen, H. S. Greig, P. Kratina, and P. L. Thompson. 2012. Warming shifts top-down and bottom-up control of pond food web structure and function. Philosophical Transactions of the Royal Society B: Biological Sciences. 367: 3008-3017.
Greig, H. S.*, P. Kratina*, P. L.Thompson, W. J Palen, J. S. Richardson, and J. B. Shurin. 2012. Warming, eutrophication and predator loss amplify subsidies between aquatic and terrestrial ecosystems. Global Change Biology. 18: 504-514. * Authors contributed equally.
Kratina, P.*, H. S. Greig*, P. L Thompson, T. S. A. Carvalho-Pereira, and J. S. Shurin. 2012. Warming modifies trophic cascades and eutrophication in freshwater ecosystems. Ecology. 93: 1421-1430. * Authors contributed equally.
Klemmer, A. J., S. A. Wissinger, H. S. Greig, and M. L. Ostrofsky. 2012. Strong single-species effects of a detritivore on multiple ecosystem processes. Journal of Animal Ecology. 81: 770-780. Highlighted feature on journal home page.
Greig, H. S., D. K. Niyogi, K. L. Hogsden, P. G. Jellyman and J. S. Harding. 2010. Heavy metals: confounding variables in the response of New Zealand freshwater fish assemblages to natural and anthropogenic acidity. Science of the Total Environment. 408: 3040-3050.
Greig, H. S. and S. A. Wissinger. 2010. Reinforcing biotic and abiotic time constraints facilitate the broad distribution of a generalist with fixed traits. Ecology. 91: 836-846.
Wissinger, S. A., H. S. Greig, and A. McIntosh. 2009. Absence of species replacements between permanent and temporary lentic habitats in New Zealand. Journal of the North American Benthological Society. 28: 12-23.
Greig, H. S., and A. R. McIntosh. 2008. Density reductions by predatory trout increase adult size and fecundity of surviving caddisfly larvae in a detritus-based stream food web. Freshwater Biology 53: 1579-1591.
Wissinger, S. A., A. R. McIntosh, and H. S. Greig. 2006. Impacts of introduced brown and rainbow trout on benthic invertebrate communities in shallow New Zealand lakes. Freshwater Biology 51:2009-2028.
Greig, H. S., and A. R. McIntosh. 2006. Indirect effects of predatory trout on organic matter processing in detritus-based stream food webs. Oikos 112:31-40. Honourable mention, Best Publication by a New Researcher, New Zealand Ecological Society, 2008.
Wardhaugh, C. W., T. J. Blakely, H. S. Greig, P. D. Morris, A. Barnden, S. Rickard, B. Atkinson, L. L. Fagan, R. M. Ewers, and R. K. Didham. 2006. Vertical stratification in the spatial distribution of the beech scale insect (Ultracoelostoma assimile) in Nothofagus tree canopies in New Zealand. Ecological Entomology 31:185-195.
McIntosh, A. R., H. S. Greig, S. A. McMurtrie, P. Nystrom, and M. J. Winterbourn. 2005. Top-down and bottom-up influences on populations of a stream detritivore. Freshwater Biology 50:1206-1218.
Insect ecology, insect pathology, invasive species, and biological control
Insect ecology, insect pathology, invasive species, and biological control
My research program focuses on insect ecology and management with an emphasis on the study of insect pathogens and invasive species. I primarily focus on fungal insect pathogens, and my program spans from more basic aspects of pathogen dynamics, epizootiology, and factors affecting disease susceptibility and defense against disease, to evaluating microbial insecticides and developing strategies for their use in integrated pest management programs. My current research focuses on the ecology and management of the invasive European red (fire) ant, Myrmica rubra, and the lily leaf beetle, Lilioceris nigripes.
Arevalo, H.A., J. Collins, E. Groden, F. Drummond, and K. Simon. 2009. Marking blueberry maggot flies (Diptera: Tephritidae) using fluorescent diet for recapture studies. Florida Entomologist 92 (2): 379-381.
Booth, S.R., F.A. Drummond, and E. Groden. 2008. Small Fruits. Pp. 597-616. In: Field Manual of Techniques in Invertebrate Pathology, 2nd ed. (L.A. Lacey and H.K. Kaya, eds). Kluwer Academic Publishers, Boston, U.S. (2nd edition of chapter).
Garnas, J., F.A. Drummond, and E. Groden. 2007. Intercolony aggression withn and among local populations of the invasive ant, Myrmica rubra (Hymenoptera: Formicidae), in coastal Maine. Environmental Entomology 36:105-113.
Klinger, E., E. Groden, and F.A. Drummond. 2006. Beauveria bassiana horizontal infection between cadavers and adults of the Colorado potato beetle, Leptinotarsa decemlineata (Say). Environmental Entomology 35(4): 992-1000.
Groden, E., F.A. Drummond, J. Garnas, and Andre Franceour. 2005. Distribution of an Invasive ant, Myrmica rubra (Hymenoptera: Formicidae), in Maine. Journal of Economic Entomology 98(6): 1774-1784.
Alyokhin, A., G. Porter, E. Groden, and F. Drummond. 2005. Colorado potato beetle response to soil amendments: A case in support of the mineral balance hypothesis? Agriculture, Ecosystems and Environment 109: 234-244.
Groden, E., F.A. Drummond, J. Garnas, and Andre Franceour. 2005. Distribution of an Invasive ant, Myrmica rubra (Hymenoptera: Formicidae), in Maine. J. Econ. Entomol. 98(6): 1774-1784
Watershed science and management
Watershed science and management
Together with students and postdoctoral fellows, my work examines the role played by flowing water as a master variable governing river ecosystems. In collaboration with experts in biomechanics and hydraulic engineering, I investigate the myriad effects of flow on ecosystem structure and function, as well as the complex ways in which human alterations of flow regimes affect river health. This research has ranged from studies of the microflow environments experienced by individual river organisms to analyses of ecosystem responses to multi-million dollar restoration programs in which dam operations have been modified to improve the health of degraded rivers.
I am more broadly engaged in multidisciplinary research to increase the effectiveness of watershed management practices, including activities such as riparian restoration, dam removal, and the control of invasive species. With the Mitchell Center for Environmental and Watershed Science I work to maximize the usefulness of multidisciplinary environmental research by developing robust partnerships with key stakeholders involved in environmental decision-making. The Mitchell Center also serves as a forum for the discussion of controversial and complex environmental issues facing Maine and other regions.
Cell and molecular biology of segmentation and muscle development in Zebrafish
Cell and molecular biology of segmentation and muscle development in Zebrafish
Muscle Development and Morphogenesis in Zebrafish
A large variety of diseases, both inherited and acquired, affect muscle tissues in humans. In order to prevent and/or treat such disease, it is necessary to understand the pathology at the cellular and molecular level. Because each step of muscle specification and differentiation translates to a progressive refinement of functional physiology, studying muscle development may lead to therapeutic insights. The goal of our laboratory is to elucidate the signaling networks that underlie the muscle morphogenesis.
We study skeletal muscle morphogenesis during zebrafish development. Skeletal muscle is comprised of segmentally reiterated myotomes. Like the mammalian tendon, the zebrafish myotome boundary transduces force from muscle to the skeletal system. Thus, myotome boundary formation, as well as skeletal muscle morphogenesis, is critical for normal development and muscle function. Our research investigates the morphogenetic signaling networks that underlie skeletal muscle and myotome boundary formation.
The zebrafish is an excellent model system with which to integrate the genetic, molecular, and cell biological mechanisms that underlie muscle development. Because the signaling networks that regulate muscle development are remarkably conserved among vertebrates, our studies may lead to novel insights into development of therapeutics for muscle and tendon diseases.
Peterson, M.T., and Henry, C.A. (2010) Hedgehog signaling and laminin play unique and synergistic roles in muscle development. Developmental Dynamics, 239 (3): 905-13
Goody, M.F., Kelly, M.W., Lessard, K.N., Khalil, A., and Henry, C.A. (2010) Nrk2b-mediated NAD+ production regulates cell adhesion and is required for muscle morphogenesis in vivo. Developmental Biology, 344(2):809-26.
Goody, M.C. and Henry, C.A. (2010) Dynamic Interactions Between Cells and their Extracellular Matrix Mediate Embryonic Development. Molecular Reproduction and Development, DOI 10.1002/mrd.21157.
Snow, C.J., Goody, M., Kelly, M.W., Oster, E.C., Jones, R., Khalil, A., and Henry, C.A. (2008) Time-lapse analysis and mathematical characterization elucidate novel mechanisms underlying muscle morphogenesis. PLoS Genetics, 4(10):e1000219
Snow, C.J., Peterson, M.T., Khalil, A., and Henry, C.A. (2008) Muscle development is disrupted in zebrafish embyros deficient for Fibronectin. Developmental Dynamics, 237 (9): 2542-53
Kok, F.O., Oster, E., Mentzer, L., Hsieh, J., Henry, C.A., Sirotkin, H.I. (2007) The role of the SPT6 chromatin remodeling factor in zebrafish embryogenesis. Developmental Biology, 307:214-226.
Henry, C.A., Poage, C.T., McCarthy, M.B., Campos-Ortega, J., and Cooper, M.S. (2005) Segmentation is Regionally Autonomous within the Zebrafish Presomitic Mesoderm Zebrafish, 2(1):7-14.
Henry, C.A., McNulty, I.M., Durst, W.A., Munchel, S.E., and Amacher, S.L. (2005) Interactions Between Muscle Fibers and Segment Boundaries in Zebrafish. Developmental Biology, 287(2): 346-60
Henry, C.A., and Amacher, S.L. (2004) Zebrafish slow muscle migration induces a wave of fast muscle morphogenesis. Developmental Cell 7 (6) 917-923
Crawford, B.C., Henry, C.A., Todd, C., and Hille, M.B. (2003) Roles for Paxillin, Focal Adhesion Kinase, and Cadherin in early morphogenesis of Zebrafish embryos. Molecular Biology of the Cell, 14: 3065-3081.
The endocrine basis of bird ecology and behavior; reproductive biology, bird migration and conservation
The endocrine basis of bird ecology and behavior; reproductive biology, bird migration and conservation
Key questions in avian biology today include: How are bird populations regulated? What factors ultimately affect survival and reproduction? How do environmental conditions during the non-breeding periods of wintering and migration ultimately influence breeding success? How do migrants prepare for and complete their journeys? These questions are applicable across a wide variety of bird species and are critical to our understanding of how bird populations are regulated and what factors need to be considered for conservation concerns. By looking at how environmental conditions (weather, food, etc.) influence energy demand throughout the annual cycle, we can gain a better understanding of how ecological, behavioral, and physiological factors act as "carry-over effects" from one stage to the next (e.g. of "seasonal interactions"). Throughout our work, plasma hormones, metabolites, immune function, and other measures of body condition are examined provide insights into how well individuals are regulating energy. Stable isotope signatures incorporated into tissues such as feathers, claws, and blood are used as biogeographic markers of where and when within the annual cycle individuals may be encountering challenges to their energy demand.
While each project has a strong "basic" research foundation, they all have an applied, conservation component that considers naturally-occurring environmental factors as well as those that occur through anthropogenic activities such as land use practices, pollution, and development. Loss of suitable resources may occur at one or more stages of the annual cycle and, ultimately, the work focuses on understanding how these stages are linked.
Current Projects include:
- Physiological Ecology of Seasonal Interactions: How Do Wintering Ground Events Constrain Breeding Success in Neotropical Migrants?
- Eco-physiological Underpinnings of Different Migration Strategies Within and Across Species.
- Bird Migration in the Gulf of Maine Region: Resource Management Through Identifying the Temporal and Spatial Patterns of Migratory Birds Along Coastal and Offshore Areas.
- Energetic Condition, Resource Quality, and Seabird Population Regulation in the Gulf of Maine.
Tonra, C.M., Marra, P.P., & Holberton, R.L. 2011. Migration phenology and winter habitat quality are related to circulating androgen in a long-distance migratory bird. J. Avian Biology doi:10.111/j.1600-0587.2011.05333.x.
Tonra, C.M., Marra, P.P., & Holberton, R.L. 2011. Early elevation of testosterone advances migratory preparation in a songbird. J. Expíl Biol. 214: 2761-2767.
Angelier, F. Tonra, C.M., Holberton, R.L., Marra, P.P. 2011. Short-term changes in body condition in relation to habitat and rainfall abundance in American redstarts, Setophaga ruticilla, during the non-breeding season. J. Avian Biology 42:335-341 (DOI:10.1111/j.1600-048X.2011.05369.x)
Angelier, F., Ballentine, B. Holberton, R.L., Marra, P.P. and Greenberg, R. 2011. What drives variation in the corticosterone stress response between subspecies?: a common garden experiment of Swamp sparrows (Melospiza georgiana). J. Evolutionary Biology 24: 1160-1392 (DOI: 10.1111/j.1420-9101.2011.02260.x)
Covino, K.M. & Holberton, R.L. 2011. The influence of energetic condition on flight initiation and orientation of migratory songbirds in the Gulf of Maine region. The Auk:313-320. (DOI:10.1525/auk.2011.09225
Wilson, C.M., Joos, R. & Holberton, R.L. in review. A comparative study of the nesting biology and parental behavior of sub-Arctic- and temperate-breeding Yellow warblers. J. of Field Ornithology.
Horton, B.M. & Holberton, R.L. 2010. Morph-specific variation in baseline corticosterone and the adrenocortical response in breeding white-throated sparrows, Zonotrichia albicollis. The Auk:127:540-548.
Angelier, F., Holberton, R.L. and Marra, P.P. 2009. Does stress response predict return rate in a migratory bird species?: A study of American redstarts and their non-breeding habitat. Proceedings of the Royal Society B: Biological Sciences 276: 3545-3551 (doi: 10.1098/rspb.2009.0868)
Angelier, F., Tonra, C.M., Holberton, R.L. and Marra, P.P. 2009. How to capture wild passerine species to study baseline corticosterone levels. J. Ornithology 151: 415-422 (DOI 10.1007/s10336-009-0471-6)
Johnston, J.C. and Holberton, R.L. 2009. Forest management and temporal effects on food availability for a ground-foraging bird (Catharus guttatus). Forest Ecology and Management 258:1516-1527.
Horton, B.M. and Holberton, R.L. 2009. Corticosterone manipulations alter morph-specific nestling provisioning behavior in male white-throated sparrows, Zonotrichia albicollis. Hormones and Behavior 56:510-518.
Readel, A.M., Warner, J.K., Holberton, R.L. and Phillips, C.A. 2008. Maturational changes in male Slider turtles (Trachemys scripta) from Illinois. Herpetological Conservation and Biology 3: 170-175.
Holberton, R.L., Boswell, T., and Hunter, M.J. 2008. Circulating prolactin and corticosterone concentrations during the development of migratory condition in the Dark-eyed Junco, Junco hyemalis. General and Comparative Endocrinology 155:641-649.
Horton, B.M., Long, J.A. and Holberton, R.L. 2007. Intraperitoneal delivery of exogenous corticosterone via osmotic pump in a passerine bird. General and Comparative Endocrinology: 152:8-13.
Wilson, C.M. and Holberton, R.L. 2007. Differences in song rate in two populations of Yellow Warblers (Dendroica petechia). Wilson Journal of Ornithology 119:132-135.
Wilson, C. M. and Holberton, R.L. 2007. Are nestlings the cue for reduction of the adrenocortical response to stress in male Yellow Warblers breeding at high latitude? Condor 109:675-679.
Holberton, R.L., Wilson, C.M., Hunter, M.J., Cash, W.B. and Sims, C.G. 2007. The role of corticosterone in supporting migratory lipogenesis of the Dark-eyed Junco, Junco hyemalis: A model for central and peripheral regulation. Physiological and Biochemical Zoology 80:125-137
Carlisle, J.D. & Holberton, R.L. 2006. Relative efficiency of a tartrate emetic for assessing diet and its deleterious effects on migratory birds: a cautionary note. Journal of Field Ornithology 77:126-135
Perkins, D.E. and Holberton, R.L. 2006. Indicators of body condition, energy demand, and breeding success in the Ruddy Turnstone, Arenaria interpres, a species of concern. In Waterbirds Around the World. Eds. G.C. Boere, C.A. Galbraith, and D. A. Stroud. The Stationery Office, Edinburgh, UK. Pp. 551-552.
Holberton, R.L. and Able, K.P. 2005. Eberhard Gwinner ñ In Memoriam. The Auk 122: in press.
Cash, W. B. and Holberton, R.L. 2005. Endocrine and behavioral response to a decline in habitat quality: effects of pond drying on the Slider Turtle, Trachemys scripta. Journal of Experimental Zoology 303A:872-879.
Holberton, R.L. and Dufty, Jr., A.M. 2005. Hormone Patterns and Variation in Life History Strategies of Migratory and Non-migratory Birds, pp 290-302 in Birds of Two Worlds: The Ecology and Evolution of Migratory Birds (Marra, P. and Goldberg, R., Eds.), Johns Hopkins Press.
Wilson, C. Morgan and Holberton, R.L. 2004. Personal risk versus immediate reproductive success: a basis for latitudinal differences in the adrenocortical response to stress in Yellow warblers, Dendroica petechia. The Auk 121: 1238-1249.
Holberton, R.L. 2004. Blackpoll Biology. p 118 In Birdlife of the Churchill Region: Status, History, Biology. J.R. Jehl, Jr., Trafford Publ., Victoria, B. C.
Wilson, C. M., and Holberton, R.L. 2004. High Latitude Hormones. p. 117 In Birdlife of the Churchill Region: Status, History, Biology. J.R. Jehl, Jr., Trafford Publ., Victoria, B. C.
Long, J. A. and Holberton, R. L. 2004 Corticosterone secretion, energetic condition, and a test of the Migration Modulation Hypothesis in the Hermit Thrush. The Auk 121: 1094-1102.
Lõhmus, M., Sandberg, R., Holberton, R. L. and Moore, Frank R. 2003. Corticosterone levels in relation to migratory readiness in Red-eyed vireos (Vireo olivaceus). Behavioral Ecology and Sociobiology 54:233-239.
Holberton, R.L. and Wingfield, J.C. 2003. Modulating the corticosterone stress response: a mechanism for balancing individual risk and reproductive success in Arctic-breeding sparrows? The Auk 120:1140-1150.
Cash, W. B. and Holberton, R.L. 2002. An apparatus to measure the locomotor activity of freshwater turtles held in captivity. Herpetological Review 33: 181-182.
Wilson, C. M. and Holberton, R.L. 2001. An alternative method for delivering adrenocorticotropin hormone in birds. Gen. Comp. Endocrinol. 122:1-5.
Mizrahi, D., Holberton, R.L. and Gauthreaux, S.A., Jr.. 2001. Plasma corticosterone and adrenocortical stress response in Semi-palmated Sandpipers, Calidris pusilla, at a major stopover site during spring migration. The Auk 118:79-91.
Holberton, R.L. and Able, K.P. 2000. Differential migration and an endocrine response to stress in wintering Dark-eyed Juncos. Proc. Royal Soc. 267:1889-1896.
Sims, C.G. and Holberton, R.L. 2000. Development of the corticosterone stress response in young mockingbirds, Mimus polyglottos. Gen. Comp. Endocrinol. 119:193-201
Holberton, R.L. 1999. Changes in patterns of corticosterone secretion concurrent with migratory fattening in a Neotropical migratory bird. Gen. Comp. Endocrinol. 116:49-58.
Cash, W.B. and Holberton, R.L. 1999. The effects of exogenous corticosterone on locomotor activity in the Red-eared Slider Turtle, Trachemys scripta elegans. J. Exp. Zool. 284:637-644.
Holberton, R.L., Marra, P.P. and Moore, F.R. 1999. Endocrine aspects of physiological condition, weather and habitat quality in landbird migrants during the non-breeding period. In Proceedings of the 22nd International Ornithological Congress, (N. J. Adams and R. H. Slotow, Eds), pp. 847-866. Johannesburg, South Africa: BirdLife South Africa.
Holberton, R.L. 1999. book review of Migration and Survival of the Birds of Asia, H. Elliott McClure. 1998. White Lotus Co., Ltd., Bangkok, Thailand. The Auk
Marra, P. P. and Holberton, R.L. 1998. Corticosterone levels as indicators of habitat quality: effects of habitat segregation in a migratory bird during the non-breeding season. Oecologia: 116:284-292.
Cash, W.B., Holberton, R.L. and Knight, S.S. 1997. Corticosterone secretion in response to capture and handling in free-living Red-eared Slider turtles. Gen. Comp. Endocrinol. 108:427-433.
Holberton, R.L., Parrish, J.D. and Wingfield, J.C., 1996. Modulation of the adrenocortical stress response in Neotropical migrants during autumn migration. The Auk 113:558-564.
Holberton, R.L., Wingfield, J.C. and Helmuth, B.S., 1996. The corticosterone-based stress response in Gentoo (Pygoscelis papua) and King (Aptenodytes patagonicus) penguins in the Antarctic winter. Condor 98:850-854.
Holberton, R.L., and Wingfield, J.C. 1994. Adrenocortical responses to stress in Antarctic seabirds. Antarctic Journal of the United States 29:167.
Wingfield, J.C., Deviche, P., Sharbaugh, S., Astheimer, L.B., Holberton, R.L., Suydam, R., and Hunt, K. 1994. Seasonal changes of the adrenocortical responses to stress in Common Redpolls, Acanthis flammea, in Alaska. J. Exp. Zool. 270:372-380.
Helmuth, B., Veit, R.R. and Holberton, R.L., 1994. Long distance dispersal of a subantarctic brooding bivalve, Gaimardia trapesina, by kelp rafting. Marine Biol. 120:421-426.
Helmuth, B., Veit, R.R. and Holberton, R.L. 1994. Dispersal of benthic invertebrates in the Scotia Arc by kelp rafting. Antarctic Journal of the United States 29:145.
Holberton, R.L. 1993. An endogenous basis for differential migration in the dark-eyed junco. Condor 95:580-587.
Holberton, R.L. and Able, K.P. 1992. Persistence of circannual cycles in a migratory bird held in constant dim light. J. Comp. Physiol. A. 171: 477-481.
Holberton, R.L., Hanano, R. and Able, K.P. 1990. Age-related dominance in male dark-eyed juncos: effects of plumage and prior residence. Anim. Behav. 40:573-579.
Holberton, R.L., Able, K.P. and Wingfield, J.C. 1989. Status signalling in dark-eyed juncos, Junco hyemalis: plumage manipulations and hormonal correlates of dominance. Anim. Behav. 37:681-689.
Neurophysiology of sensory and motor systems; biological rhythms; cellular neurobiology of vision; gene expression in frog oocytes
Neurophysiology of sensory and motor systems; biological rhythms; cellular neurobiology of vision; gene expression in frog oocytes
This laboratory is generally concerned with understanding the workings of the brain and nervous system. The specific areas of research investigate the visual system and biological rhythms. Vision is explored by using the latest methodological techniques for whole-cell (WCR) and single channel voltage-clamp recordings from single isolated photoreceptors. These methods are applied to the classical preparation of Limulus ventral photoreceptor because of many special attributes: they are large, isolated, robust, exhibit unitary quantal bumps, and are dramatically altered by a circadian clock in the animal's brain. Currently, recording or pharmacologically blocking specific membrane channels is leading to an understanding of photoreceptor function. Cellular mechanisms are further explored by injecting into these photoreceptors specific biochemical agents that inhibit or stimulate G-proteins, Calmodulin, Calcineurin, cAMP, cGMP, IP3, phosphatases, and various kinases. In short, these studies, along with collaborations with labs outside the state, are leading to a complete neurophysiological and biochemical understanding of cell function, and the role of the photoreceptor in an animal's behavior. Mathematical modelling of photoreceptor kinetics is currently being pursued through a collaborative venture with the Math Department.
Other areas of research involve standard recording, staining, and tracing the pathways of neurons in the central nervous system of Limulus, especially those cells involved in the visual pathway or part of the biological clock circuitry. This laboratory is one of several around the world whose ultimate goal is to understand animal behavior starting at the origin of vision (i.e., the photorecptor cell) and proceeding into the brain (neurocircuitry and pathways) and ultimately to changes in behavior, as studied in the lab and in the field.
Kass, L., D.Z. Ellis, J. Pelletier, N.E. Tableman, and S.C. Edwards (1998) Inhibition of the calcineurin-like phospatase activity in Limulus ventral eye photoreceptor cells alters the characteristics of the spontaneous quantal bumps and the light-mediated inward currents, and enhances arrestin phosphorylation. Visual Neuroscience 15: 1039-1049.
Wharten, D.N., R.N. Jinks, B.-A. Battelle, E.D. Herzog, L. Kass, G.H. Renninger and S.C. Chamberlain. (1997) Morphology of the eye of the hydrothermal vent shrimp, Alvinocaris markensis. Journal of Marine Biological Association U.K. 77:1097-1108.
Lakin, R.C., R.N. Jinks, B.-A. Battelle, E.D. Herzog, L. Kass, G.H. Renninger and S.C. Chamberlain. (1997) Retinal anatomy of Chorocharis chacei, a deep-sea hydrothermal vent shrinp from the Mid-Atlantic Ridge. Journal Comparative Neurology. 384.
Gaus, G., M. Casaretto, and L. Kass (1997) The effect of neuropeptides from Limulus on its circadian rhythm in retinal sensitivity. Journal of Comparative Physiology A. 180:137-142.
Kass, L. and W.O. Bray (1996) Kinetic model for phototransduction and G-Protein enzyme cascade: Understanding quantal bumps during inhibition of CaM-KII or PP2B. Journal of Photochemistry and Photobiology B. 35:105-113.
Zhang, H.-j., Jinks, R.N., Wishart, A.C., Battelle, B.-a., Chamberlain, S.C., Fahrenbach, W.H. and Kass, L. 1994. An enzymatically enhanced recording technique for Limulus ventral photoreceptors: Physiology, biochemistry, and morphology. Visual Neuroscience. 11: 41-52.
Kass, L. and Barlow, Jr. R.B. 1992. A circadian clock in the Limulus brain transmits synchronous efferent signals to all eyes. Visual Neuroscience. 9: 493-504.
Powers, M.K., Barlow, Jr. R.B. and Kass, L. 1991. Visual performance of horseshoe crabs day and night. Visual Neuroscience. 7: 179-189.
Contemporary evolution, Eco-evolutionary dynamics, population and conservation genetics; fish biology
Research in my lab generally involves evolution of populations in the wild, often with an emphasis on evolution over contemporary time scales and its implications for population colonization, adaptation and broader scales of diversity. This work has incorporated aspects of population ecology and genetics, morphometrics, physiology and behavior. I believe that evolutionary biology has the potential to become increasingly applied, a goal that does not mean it must sacrifice theoretical development. Indeed, applied evolutionary biology stands not only to provide practical conservation tools, but also to focus evolutionary work on more realistic conceptualizations of natural patterns and processes. Because of this view, my research has ranged from theoretical and experimental studies of rapid evolution to conservation genetics of fish populations. While I have traditionally dealt with populations of salmonid fishes, species of considerable economic and social concern, I am also interested in similar lines of investigation involving other taxa.
Palkovacs, E.P., M.C. Marshall, B.A. Lamphere, B.R. Lynch, D.J. Weese, D.F. Fraser, D.N. Reznick, C.M. Pringle and M.T. Kinnison. 2009. An experimental evaluation of evolution and coevolution as agents of ecosystem change in tropical streams. Philosophical Transactions of the Royal Society of London, B 364:1617-1628.
Gordon, S.P., D.N. Reznick, M.T. Kinnison, M.J. Bryant, D.J. Weese, K. Rasanen, N.P. Millar and A.P. Hendry. 2009. Adaptive changes in life history and survival following a new guppy introduction. American Naturalist 174:34-45.
Horton, G.E., B.H. Letcher, M.M. Bailey and M.T. Kinnison. 2009. Atlantic salmon (Salmo salar) smolt production: the relative importance of survival and body growth. Canadian Journal of Fisheries and Aquatic Sciences 66:471-483.
Holbrook, C. M., J. Zydlewski, D. Gorsky, S. L. Shepard and M.T. Kinnison. 2009. Movements of pre-spawn adult Atlantic salmon near hydroelectric dams in the lower Penobscot River, Maine, USA. North American Journal of Fisheries Management 29:495-505.
Darimont, C.T., S.M. Carlson, M.T. Kinnison, P.C. Paquet, T.E. Reimchen and C.C. Wilmers. 2009. Human predators outpace other agents of trait change in the wild. Proceedings of the National Academy of Sciences 106:952-954.
Hendry, A.P., T.J. Farrugia and M.T. Kinnison. 2008. Human influences on rates of phenotypic change in wild animal populations. Molecular Ecology 17:20-29 (doi: 10.1111/j.1365-294X.2007.03428.x).
Kinnison, M.T., M.J. Unwin and T.P. Quinn. 2008. Eco-evolutionary vs. habitat contributions to invasion in salmon: experimental evaluation in the wild. Molecular Ecology 17:405-414 (doi: 10.1111/j.1365-294X.2007.03495.x).
Michaud, W.K., M. Power and M.T. Kinnison. 2008. Trophically mediated divergence of Arctic charr (Salvelinus alpinus L.) populations in contemporary time. Evolutionary Ecology Research 10:1051-1066.
Ozgo, M. and M.T. Kinnison. 2008. Contingency and determinism during rapid convergent evolution in the land snail, Cepaea nemoralis. Evolutionary Ecology Research. 10:721-733.
Chytridiomycete systematics and phylogeny; chytrid pathogen of amphibians
Chytridiomycete systematics and phylogeny; chytrid pathogen of amphibians
In our lab we study the systematics and ecology of aquatic fungi. Currently we focus on determining species diversity and monophyletic genera in the Chytridiomycetes (Chytridiomycota). This involves isolating and maintaining chytrids in pure culture, documenting developmental morphology at the light microscopic level, determining taxonomic characters from serial sections of zoospores viewed with transmission electron microscopy, and determining and analyzing molecular characters. We also isolate and study Batrachochytrium dendrobatidis, a chytrid pathogen of amphibians, and make cultures of this fungus available to other researchers.
Wakefield, W.S, M.J. Powell, P.M. Letcher, D.J.S. Barr, P.F. Churchill, J.E. Longcore, S-F. Chen. 2010. A molecular phylogenetic evaluation of the Spizellomycetales. Mycologia 102: 596-604.
Schloegel, L.M., C.M. Ferreira, T.Y. James, M. Hipolito, J.E. Longcore, A.D. Hyatt, M. Yabsley, A.M.C.R.P.F.Martins, R. Mazzoni, A.J. Davies, P. Daszak. 2009. The North American bullfrog as a reservoir for the spread of Batrachochytrium dendrobtidis in Brazil. Animal Conservation 13: (Suppl. 1) 1-9.
Krings, M., N. Dotzler, J.E. Longcore, T.N.Taylor. 2010. An unusual microfungus in a fungal spore from the Lower Devonian Rhynie chert. Palaeontology 53: 753-759.
James, T.Y., A.P. Litvintseva, R.Vilgalys, J.A.T. Morgan, J.W. Taylor, M.C. Fisher, L. Berger, C. Weldon, L. du Preez, J.E. Longcore. 2009. Rapid global expansion of the fungal disease chyridiomycosis into declining and healthy amphibian populations. PLoS Pathogens 5(5): e1000458. doi:10.1371/journal.ppat.1000458.
Freeman, K.R., A.P. Martin, D. Karki, R.C. Lynch, M.S. Mitter, A.F. Meyer, J.E. Longcore, D.R. Simmons, S.K. Schmidt. 2009. Evidence that chytrids dominate fungal communities in high-elevation soils. PNAS 106: 18315-18320.
Simmons, D.R., T.Y. James, A. Meyer, J.E. Longcore. 2009. Lobulomycetales, a new order in the Chytridiomycota. Mycological Research 113: 450-460.
Mozley-Standridge, S., P.M. Letcher, J.E. Longcore, D. Porter, D.R. Simmons. 2009. Cladochytriales: a new order in Chytridiomycota. Mycological Research 113: 498-507.
Frias-Alvarez, P., V.T. Vredenburg, M. Familiar-Lopez, J.E Longcore, E. Gonzalez-Bernal, G. Santos-Barrera, L. Zambrano, G. Parra-Olea. 2008. Chytridiomycosis survey in wild and captive Mexican amphibians. EcoHealth 5: 18-26.
Kirshtein, J.D., C.W. Anderson, J.S. Wood, J.E. Longcore, M. A. Voytek. 2007. Quantitative PCR detection of Batrachochytrium dendrobatidis DNA from sediments and water. Diseases of Aquatic Organisms 77: 11-15.
Longcore, J.R., J.E. Longcore, A.P. Pessier and W.A. Halteman. 2007. Chytridiomycosis widespread in anurans of northeastern United States. Journal of Wildlife Management 71: 435-444.
Morgan, J.A.T., V.T. Vredenburg, L.J. Rachowicz, R.A. Knapp, M.J. Stice, T. Tunstall, R E. Bingham, J.M. Parker, J.E. Longcore, C. Moritz, C.J. Briggs, J.W. Taylor. 2007. Population genetics of the frog-killing fungus Batrachochytrium dendrobatidis. Proceedings of the National Academy of Sciences USA 104: 13845-13850.
Johnson, P. T. J., J. E. Longcore, D. E. Stanton, R. B. Carnegie, J. D. Shields, E. R. Preu, 2006. Chytrid infections of Daphnia pulicaria: development, ecology, pathology and phylogeny of Polycaryum laeve. Freshwater Biology 51:634-648.
James, T.Y., F. Kauff, C.L. Schoch, P.B. Matheny, V. Hofsetter, C.J. Cox, G. Celio, C. Gueidan, E. Fraker, J.H. Maidlikowska, T. Lumbsch, A. Rauhut, V. Reeb, A.E. Arnold, A. Amtoft, J.E. Stajich, K. Hosaka, G.-H. Sung, D. Johnson, B. O'Rourke, M. Crockett, M. Binder, J. M. Curtis, J. C. Slot, Z. Wang, A. W. Wilson, A. Schassler, J. E. Longcore, K. O'Donnell, S. Mozley-Standridge, D. Porter, P.M. Letcher, M.J. Powell, J.W. Taylor, M.M. White, G. W. Griffith, D.R. Davies, R.A. Humber, J.B. Morton, J. Sugiyama, A.Y. Rossman, J.D. Rogers, D.H. Pfister, D. Hewitt, K. Hansen, S. Hambleton, R.A. Shoemaker, J. Kohlmeyer, B. Volkmann-Kohlmeyer, R.A. Spotts, M. Serdani, P.W. Crous, K.W. Hughes, K. Matsuura, E. Langer, G. Langer, W.A. Untereiner, R. Lacking, B. Badel, D.M. Geiser, A. Aptroot, P. Diederich, I. Schmitt, M. Schultz, R. Yahr, D.S. Hibbett, F. Lutzoni, D.J. McLaughlin, J.W. Spatafora and R. Vilgalys, 2006. Reconstructing the early evolution of fungi using a six-gene phylogeny. Nature 443:818-822.?
James, T.Y., P.M. Letcher, J.E. Longcore, S.E. Mozley-Standbridge, D. Porter, M.J. Powell, G.W. Griffith, R. Vilgalys. 2006. A molecular phylogeny of the flagellated fungi (Chytridiomycota) and description of a new phylum (Blastocladiomycota). Mycologia 98: 860-871.
Letcher, P.M., M.J. Powell, J. G. Chambers, J.E. Longcore, P.F. Churchill, P.M. Harris. 2005. Ultrastructural and molecular delineation of the Chytridiaceae (Chytridiales). Canadian Journal of Botany 83:1561-1573.
Large scale ecology and global change
Large scale ecology and global change
I study questions pertaining to biodiversity at large scales - large areas of space, long periods of time, many species. These questions have been deemphasized in ecology due to the difficulty in doing experiments, but are of high relevance to conservation and management questions. I have two broad research questions. One is developing the ability to predict how species ranges will respond to climate change. The other is finding ways to measure the impact of humans (especially land cover change) on community structure.
Magurran, Anne and Brian J. McGill co-editors of "Biological diversity: frontiers in measurement and assessment" Oxford University Press
Samson, J ; Berteaux, D; McGill, Brian J. and Humphries, M – "Geographic disparities and moral hazards in the predicted impacts of climate change on human populations" (Global Ecology and Biogeography in press)
Messier, Julie; Brian J. McGill and Martin Lechowicz – "How do leaf traits vary across ecological scales?" (Ecology Letters 2010) 13:838-848)
McGill, Brian J. – "Matters of Scale" (Science 2010) 328(30 Apr):575-576
McGill, Brian J. – "Towards a unification of unified theories of biodiversity" (Ecology Letters 2010) 13(5):627-642
McGill, Brian J; Rampal S. Etienne; John S. Gray and 15 other authors – "Species Abundance Distributions: moving beyond single prediction theories to integration within an ecological framework" (Ecology Letters 2007 10:995-1015)
McGill, Brian J; Brian Enquist, Evan Weiher and Mark Westoby – "Rebuilding community ecology from functional traits" (Trends in Ecology and Evolution 2006 21(4):178-185)
McGill, Brian J; Hadly, Elizabeth A; Maurer, Brian A "Community inertia of Quaternary small mammal assemblages in North America" (Proceedings of the National Academy of Science 2005 102:16701-16706)
McGill, Brian J - "A test of the unified neutral theory of biodiversity" (Nature 2003 vol 422(24 April): 881-885)
ecosystem ecology, aquatic ecology, terrestrial-aquatic linkages, biogeochemistry, climate change
I am an ecosystem ecologist with broad interests in aquatic-terrestrial linkages and the interactions between climate change and biogeochemical cycling in aquatic ecosystems.
ecosystem ecology, aquatic ecology, terrestrial-aquatic linkages, biogeochemistry, climate change
I am interested in the human influence on ecosytem processes, and the role of restoration on linking structure and function in disturbed systems. My current research focuses on climate change and its influence on altering production and nutrient cycling in warming high Arctic lakes. Through collaborations with contemporary ecologists and paleoecologists, I have become interested in the role that climate change may have on the invasion of forests by insect pests and the regulation of aquatic systems as a result of the death of key tree species (e.g. Hemlock woolly adelgid).
Northington R.M., J.R. Webster, E.F. Benfield, B.M. Cheever, and B.R. Niederlehner. 2013. Ecosystem function in headwater streams during active infestation by hemlock woolly adelgid. PLOS ONE 8: 1-8, doi: 10.1371/journal.pone.0061171.t001 Hershey A.E., R.M. Northington, and S.C. Whalen. 2013. Methane processing in a small arctic lake: temporal variation in production, methanogensis pathways, and methane oxidation. Biogeochemistry, In Press. Northington, R.M., J.R. Webster, E.F. Benfield, S.H. Shoenholtz, A.J. Timpano, and C. Zipper. 2011. An assessment of structural attributes and ecosystem function in restored Virginia coalfield streams. Hydrobiologia 671: 51-63. Northington, R.M., M.D. Keyse, S.R. Beaty, S.C. Whalen, E.R. Sokol, and A.E. Hershey. 2010. Benthic secondary production in eight oligtrophic arctic Alaskan lakes. Journal of the North American Benthological Society 29: 465-479. Hershey, A.E., E. Binkley, K. Fortino, M.D. Keyse, C. Medvedeff, and R.M. Northington. 2010. Utilization of carbon sources of allochthonous and autochthonous origins by Chironomus in arctic lakes. Verh. Internat. Verein. Limnol. 30: 1321-1325. Hershey, A.E., G.A. Lamberti, D.T. Chaloner, and R.M. Northington. 2010. Aquatic insect ecology. Pages 659-694 in Thorp, J.H. and A.P. Covich (eds.), Ecology and Classification of North American Freshwater Invertebrates. 3rd Edition., Elsevier Press. Northington, R.M., and A.E. Hershey. 2006. Effects of stream restoration and wastewater treatment plant effluent on fish communities in urban streams. Freshwater Biology 51: 1959-1973.
Avian ecology, behavior, demography, mating systems, and life history evolution
Avian ecology, behavior, demography, mating systems, and life history evolution
My research focuses on the ultimate processes that generate vertebrate diversity, including genetically or culturally transmitted traits or those that arise through phenotypic plasticity. What environmental factors encourage plasticity in individuals? Shape the level of variation within and among populations? Lead to isolation among gene pools? How does habitat alteration or climate change alter these processes?
Paleolimnology, phytoplankton ecology, lake ecosystem response to global change
Paleolimnology, phytoplankton ecology, lake ecosystem response to global change
My main research interests involve paleolimnology and phytoplankton ecology, as I use diatom fossil records in lake sediments to reconstruct environmental change over time. My approach differs from conventional reconstructions involving diatom profiles in that I apply information from both field observations and bioassays to the sediment records, and I use patterns in the sediment record to pose testable hypotheses about mechanisms driving observed changes. My research also focuses on understanding current responses of lake ecosystems to climate change. I am currently conducting research in alpine, saline, and boreal lakes.
Saros, J.E., Rose, K.C., Clow, D.W., Stephens, V.C., Nurse, A.B., Arnett, H.A.*, Stone, J.R., Williamson, C.E. & A.P. Wolfe. 2010. Melting alpine glaciers enrich high-elevation lakes with reactive nitrogen. Environmental Science & Technology 44: 4891-4896.
Saros, J.E., Clow, D.W., Blett, T. & A.P. Wolfe. 2010. Critical nitrogen deposition loads in high- elevation lakes of the western U.S. inferred from paleolimnological records. Water, Air & Soil Pollution, DOI 10.1007/s11270-010-0526-6.
Hobbs, W.O., Telford, R.J., Birks, H.J.B., Saros, J.E., Hazewinkel, R.R.O., Perren, B.B., Saulnier-Talbot, E. & A.P. Wolfe. 2010. Quantifying recent ecological changes in remote lakes of North America and Greenland using sediment diatom assemblages. PLoS One 5(4): e10026. doi:10.1371/journal.pone.0010026.
Williamson, C.E., Salm, C.R.*, Cooke, S.L. & J.E. Saros. 2010. How do UV, temperature, and zooplankton influence the dynamics of alpine phytoplankton communities? Hydrobiologia 648: 73-81.
Winn, N., C.E. Williamson, R. Abbitt, K. Rose, W. Renwick, M. Henry and J.E. Saros. 2009. Modeling dissolved organic carbon (DOC) in subalpine and alpine lakes with GIS and remote sensing. Landscape Ecology 24: 807-816
Rose, K.C., C.E. Williamson, J.E. Saros, R. Sommaruga and J.M. Fischer. 2009. Differences in UV transparency and thermal structure between alpine and subalpine lakes: implications for organisms. Photochemical and Photobiological Sciences 8: 1244-1256.
Scott, C.E., Saros, J.E., Williamson, C.E., Salm, C.R., Peters, S.C. and D.L. Mitchell. 2009. Effects of nutrients and dissolved organic matter on the response of phytoplankton to ultraviolet radiation: experimental comparison in spring versus summer. Hydrobiologia 619: 155-166.
Williamson, C.E., Saros, J.E. and D.W. Schindler. 2009. Sentinels of change. Science 323: 887- 888.
Salm, C.R., J.E. Saros, S.C. Fritz, C.L. Osburn and D.M. Reineke. 2009. Phytoplankton productivity across prairie saline lakes of the Great Plains (USA): A step toward deciphering patterns through lake classification models. Canadian Journal of Fisheries and Aquatic Sciences 66: 1435-1448.
Salm, C.R., Saros, J.E., Martin, C.S. and J.M. Erickson. 2009. Patterns of seasonal phytoplankton distribution in prairie saline lakes of the northern Great Plains (U.S.A.) Saline Systems 5:1-13.
Saros, J.E. 2009. Integrating neo- and paleolimnological approaches to refine interpretation of environmental change. Journal of Paleolimnology 42: 243-252. Invited Deevey-Frey Review.
Science education
Science education
Michelle Smith's work focuses on how to help students learn biology and teachers adopt promising educational practices in their classrooms. Specifically, she is interested in investigating the origins of pervasive misunderstandings in genetics, determining what aspects of peer discussion make it an effective learning tool in both large-lecture and small-enrollment courses, and collaborating with biology teachers on science education research questions in an effort to facilitate course transformation.
Batz Z, Olsen B, Dumont J, Dastoor F, Smith MK. Helping Struggling Students in Introductory Biology: A Peer Tutoring Approach that Improves Performance, Perception, and Retention. CBE-Life Sci Edu, 2015, 14:1-12.
Smith MK, Vinson EL, Smith JA, Lewin JD, Stetzer M. A Campus-Wide Study of STEM Courses: New Perspectives on Teaching Practices and Perceptions. CBE-Life Sci Educ. 2014, 13:624-635.
Smith MK, Merrill S. Why do Some People Inherit a Predisposition to Cancer? A small group activity on cancer genetics. CourseSource. 2014, http://coursesource.org/courses/why-do-some-people-inherit-a-predisposition-to-cancer-a-small-group-activity-on-cancer
Freeman S, Eddy SL, McDonough M, Smith MK, Okoroafor N, Jordt H, Wenderoth MP. End of lecture: Active learning increases student performance across STEM disciplines. PNAS. 2014, 11(23):8410-8415.
Smith MK, Jones FHM, Gilbert SL, Wieman CE. The Classroom Observation Protocol for Undergraduate STEM (COPUS): A New Instrument to Characterize University STEM Classroom Practices. CBE-Life Sci Educ. 2013 Winter, 12(4):618-627.
Knight JK, Wood WB, Smith MK.What's Downstream? A Set of Classroom Exercises to Help Students Understand Recessive Epistasis. Journal of Microbiology & Biology Education. 2013, 14(2) http://jmbe.asm.org/index.php/jmbe/article/view/560
Smith MK, Wenderoth MP, Tyler M. The teaching demonstration: what faculty expect and how to prepare for this aspect of the job interview. CBE - Life Sci Educ. 2013, Spring 12(1):12-18.
Smith MK, Annis SL, Kaplan JJ, Drummond F. Using peer discussion facilitated by clicker questions in an informal education setting: enhancing farmer learning of science. PLoS-ONE. 2012, 7(10): e47564. doi:10.1371/journal.pone.0047564
Smith MK, Thomas K, Dunham M. In-class Incentives that Encourage Students to Take Concepts Assessments Seriously. Journal of College Science Teaching. 2012, 42(2): 57-61.
Smith MK and Knight JK. Using the genetics concept assessment to document persistent conceptual difficulties in undergraduate genetics courses. Genetics. 2012, 181(1):21-32.
Smith MK. A fishy way to discuss multiple genes affecting the same trait. PLoS-Biol. 2012, 10(3): e1001279. doi:10.1371/journal.pbio.1001279
Semsar K, Knight JK, Birol G, Smith MK. The Colorado Learning Attitudes about Science Survey (CLASS) for use in Biology. CBE - Life Sci Educ. 2011, Fall; 10(3):268-278
Smith MK, Wood WB, Krauter K, Knight JK. Combining peer discussion with instructor explanation increases student learning from in-class concept questions. CBE - Life Sci Educ. 2011, Spring; 10(1):55-63. Also featured in the Highlights of 2011 print edition.
Smith MK, Trujillo C, Su TT. The benefits of using clickers in small enrollment seminar-style biology courses. CBE - Life Sci Educ. 2011, Spring; 10(1):14-17.
Haudek KC, Kaplan JJ, Knight J, Long T, Merrill J, Munn A, Nehm N, Smith M, Urban-Lurain M. Harnessing Technology to Improve Formative Assessment of Student Conceptions in STEM: Forging a National Network. CBE – Life Sci Educ. 2011, Summer; 10(2):149-155.
Smith MK and Perkins KK. "At the end of my course, students should be able to …": The benefits of creating and using effective learning goals. Microbiology Australia. 2010, 31(1):35-37.
Knight JK and Smith MK. Different but equal? How non-majors and majors approach and learn genetics. CBE - Life Sci Educ. 2010, Spring; 9(1):34-44.
Smith MK, Wood WB, Adams WK, Wieman C, Knight JK, Guild N, Su TT. Why peer discussion improves student performance on in-class concept questions. Science. 2009, 323(5910):122-124.
Smith MK, Wood WB, Knight JK. The Genetics Concept Assessment: a new concept inventory for gauging student understanding of genetics. CBE - Life Sci Educ. 2008 Winter; 7(4):422-430. Also featured in the Highlights of 2008 print edition.
Smith M, Wakimoto B. Complex regulation and multiple developmental functions of misfire, the Drosophila melanogaster ferlin gene. BMC Developmental Biology. 2007, 7:21-36.
Dorman J, Smith M, O'Brien S, Freisem, K. Teaching in Lab Settings. In C. Ross and J. Dunphy (Eds.), Strategies for Teaching Assistant and International Teaching Assistant Development: Beyond Micro Teaching, 2007. Anker Publishing.
Communication between the brain and peripheral organs/tissues in the regulation of energy balance, diabetes, obesity and body weight; CNS control of appetite and sympathetic activation of brown and white adipose tissues; adult neural plasticity; neurotrophic factors and neuropathy; CNS fuel utilization and energetics.
Communication between the brain and peripheral organs/tissues in the regulation of energy balance, diabetes, obesity and body weight; CNS control of appetite and sympathetic activation of brown and white adipose tissues; adult neural plasticity; neurotrophic factors and neuropathy; CNS fuel utilization and energetics.
Research in the Townsend Lab focuses on the mechanisms by which the body maintains or loses energy balance, which is the balance between energy intake (comprised of dietary components, neural control of appetite, and digestion and nutrient absorption) and energy expenditure (comprised of basal metabolism, mitochondrial function, thermogenesis, and physical activity). The brain, or central nervous system (CNS) is the part of the body responsible for coordinating and controlling these energy balance processes, and is in communication with other metabolic organs and tissues via a 2-way system that includes: neural connections with the brain (such as the sympathetic nerves) and endocrine products released from metabolic organs and tissues which reach the brain through the systemic circulation. Current projects in the lab seek to better understand the role of the growth factors called Bone Morphogenetic Proteins (BMPs) in regulating energy balance, as well as the involvement of neuronal plasticity, both in the brain and in adipose tissue. The over-arching goal is to develop a deeper mechanistic understanding of how the body maintains energy balance, in order to prevent and treat metabolic diseases such as obesity and diabetes.
Developmental biology; organogenesis; and the creation of multimedia educational materials in development.
Developmental biology; organogenesis; and the creation of multimedia educational materials in development.
My field of study is developmental biology. In this area, I am interested primarily in genetic controls and tissue interactions during embryonic development. I examine these using experimental and histological techniques. Presently, I work with digital video in the production of films and CD-ROMs of developing systems. I collaborate with Ronald Kozlowski in producing multimedia educational materials in developmental biology. I am also engaged in research on the history of embryology and the impact of modern developmental techniques on society. In this area, my concern is writing articles for general audiences.
Tyler, M., R. Cowan, F. Dastoor, B. Olsen, J. Lockhart, and M. Harris, 2009. Helping students understand the process of science: using inquiry-based labs and lecture videos in a large introductory biology course. Invited NSF-AAAS Meeting: Vision and Change in Undergraduate Biology Education. July 15-17, 2009. Washington, D.C. http://www.visionandchange.org/index.php/about/
Tyler, M.S., 2008. Introducing Inquiry-Based Labs into a Large Introductory Biology Course: Step One, Step Two… National Conference and Summer Academy "Integrating Science and Mathematics Education Research into Teaching: Resources and Tools for Improved Learning" June, 2008
Mary E. Rumpho, Jared M. Worful, Jungho Lee, Mary S. Tyler, Krishna Kannan, Kara M. Soule, and James R. Manhart, 2007. The Search for Horizontal Gene Transfer in a Kleptoplastic Sea Slug. American Society of Plant Biologists 2007 Meeting, July, 7-11, Chicago, IL.
Tyler, M.S., R.N. Kozlowski, and S.F. Gilbert, 2003. Differential Expression: Key Experiments in Developmental Biology. Sinauer Associates, Sunderland, MA. A set of six movies on CD-ROM.
Tyler, M.S. and R. Kozlowski 2003. Vade Mecum2: An Interactive Guide to Developmental Biology. (CD-ROM). Sinauer Associates.
Tyler, M.S. 2003. Developmental Biology: A Guide for Experimental Study, 3rd Edition. Sinauer Assoc., Inc., Sunderland, Massachusetts.
Tyler, M.S., and R.N. Kozlowski, 2003. Fly Cycle 2. Sinauer Associates, Sunderland, MA. An interactive CD-ROM and a DVD.
Tyler, M.S. and R. Kozlowski 2000. Vade Mecum: An Interactive Guide to Developmental Biology. (CD-ROM). Sinauer Associates.
Tyler, M.S. 2000. Developmental Biology: A Guide for Experimental Study, 2nd Edition. Sinauer Assoc., Inc., Sunderland, Massachusetts.
Tyler, M.S., R. Kozlowski, L. Iten 1998. Fly Cycle: The Lives of a Fly, Drosophila melanogaster. A film on interactive CD-ROM. Sinauer Associates.
Tyler, M.S. 1998. Embryology. In: Encyclopedia Americana. Grolier, Inc., Betel, CT
Watler-Schnetzer, J.N., and M.S. Tyler, 1996. Endogenous ß-galactosidase activity in the larval, pupal, and adult stages of the fruit fly, Drosophila melanogaster indicates need for caution in lacZ fusion gene studies. Biology Bulletin 190: 173-187.
Tyler, M.S. 1994. Stalking amphibians. Maine Naturalist: 5: 22-30.
Invertebrate biology; electron and fluorescence microscopy; phylogeny of lower invertebrates; meiofauna
Invertebrate biology; electron and fluorescence microscopy; phylogeny of lower invertebrates; meiofauna
Invertebrate biology is the broad area of my research interests, and I concentrate on invertebrates of the meiofauna---that is, small animals living in the interstices of marine sediments, especially the more primitive worms such as acoels and other turbellarians, gnathostomulids, and gastrotrichs. I apply electron microscopy and laser scanning microscopy to these animals, comparing their anatomies in search of clues to phylogenetic relationships among major taxa and clues to the functional morphology of their microorgans. A recent major project centers on phylogenetic relationships of three groups of lower worms: Acoela, Catenulida, and Gnathostomulida. The acoels and gnathostomulids have both served in some theories of animal evolution as the most primitive of the bilaterally symmetrical metazoans (all animals outside of cnidarians and sponges). Through collaboration with Dr. Matt Hooge (UMaine) and Dr. Wolfgang Sterrer (Bermuda Aquarium and Zoo) we have sampled these taxa worldwide and applied information from our detailed morphological studies to hypotheses of phylogenetic relationships that we and other collaborators have generated from DNA-sequence data. The correlations contribute to understanding how key characteristics of these worms evolved and how the animals are related to each other and to the rest of the animal phyla. From such understandings come better means for classifying the animals in formal taxonomy.
As a member of a team of programmers developing a learning-management system, I engage in a form of pedagogical research about how best to apply multimedia in teaching, how to meet a diversity of learning styles among students, and how to gauge progress in achieving learning objectives.
Kolasa, J. and S. Tyler (2009) Flatworms: Turbellarians and Nemertea. In: Thorp, J. H., ed. Ecology and Classification of North American Freshwater Invertebrates. Third Edition. Academic Press.
Achatz, J.G., M.D. Hooge, A. Wallberg, U. Jondelius, and S. Tyler (2009) Revision of acoels with 9+0 sperm ultrastructure (Convolutida) and the influence of sexual conflict on morphology. Journal of Zoological Systematics and Evolutionary Research. (in press)
Egger B., D. Steinke, H. Tarui, K. De Mulder, D. Arendt, G. Borgonie, N. Funayama, R. Gschwent- ner, V. Hartenstein, B. Hobmayer, M. Hooge, M. Hrouda, S. Ishida, C. Kobayashi, G. Kuales, O. Nishimura, D. Pfister, R. Rieger, W. Salvenmoser, J. Smith, U. Technau, S. Tyler, K. Agata, W. Salzburger, and P. Ladurner (2009) To be or not to be a flatworm: The acoel controversy. PLoS ONE 4(5): e5502. doi:10.1371/journal.pone.0005502.
Available at here
Todt, C., and S. Tyler (2007). Ciliary receptors associated with the mouth and pharynx of Acoela (Acoelomorpha): a comparative ultrastructural study. Acta Zoologica 88:41-58.
Achatz, J., M.D. Hooge, S. Tyler (2007) Convolutidae (Acoela) from Belize. Zootaxa 1479:35-66.
Hooge, M.D., and S. Tyler (2007) Acoela (Acoelomorpha) from Belize. Zootaxa 1479:21-33.
Hooge, M.D., and S. Tyler (2006) Concordance of molecular and morphological data: Example of the Acoela. Integrative and Comparative Biology 46:118-124.
Todt, C., and S. Tyler (2006) Morphology and ultrastructure of the pharynx in Solenofilomorphidae (Acoela). J. Morphology 267:776-792.
Petrov, A., M.D. Hooge, and S. Tyler (2006). Comparative morphology of bursal nozzles in acoels (Acoela, Acoelomorpha). Journal of Morphology 267: 634-648.
Hooge, M.D., and S. Tyler (2005) New tools for resolving phylogenesis: A systematic revision of the Convolutidae (Acoelomorpha, Acoela). J. Zoological Systematics and Evolution Research 43: 100-113
Hooge, M.D., and N. Eppinger (2005) New species of Acoela (Acoelomorpha) from the Gulf of California. Zootaxa 1009: 1-14
Ogunlana MV, Hooge MD, Tekle YI, Benayahu Y, Barneah O, Tyler S (2005) Waminoa brickneri n. sp. (Acoela: Acoelomorpha) associated with corals in the Red Sea. Zootaxa 1008: 1-11
Tyler, S., and M.D. Hooge (2004) Comparative morphology of the body wall of flatworms (Platyhelminthes). Can. J. Zool. 82:193-210.
Petrov, A., M.D. Hooge, and S. Tyler (2004). Ultrastructure of sperm in acoels (Acoela, Platyhelminthes) and its concordance with molecular systematics. Invertebrate Biology 123:183-197
Hooge, M.D., and S. Tyler (2003) Acoels (Platyhelminthes, Acoela) from the Atlantic coast of North America. Meiofauna Marina 12:1-30
Sørensen, M.V., P. Funch, M. Hooge, and S. Tyler (2003) Musculature of Notholca acuminata (Rotifera: Ploima: Brachionidae) revealed by confocal scanning laser microscopy. Invertebrate Biology, 122:223-230.
Tyler, S. (2003) Epithelium---the primary building block for metazoan complexity. Integrative and Comparative Biology 43:55--63.
Gschwentner, R., J. Mueller, P. Ladurner, R.M. Rieger, and S. Tyler (2003) Unique patterns of longitudinal body-wall musculature in the Acoela: The ventral musculature of Convolutriloba longifissura. Zoomorphology 122(2):55-62.
Hooge, M.D., and S. Tyler (2003) Two new acoels (Platyhelminthes, Acoela) from the central coast of California. Zootaxa 131:1-14.
Sørensen, M.V., S. Tyler, M. Hooge, and P. Funch (2003) Organization of the pharyngeal hard parts and musculature in Gnathostomula armata (Gnathostomulida: Gnathostomulidae). Can. J. Zool. 81:1463-1470
Hooge M.D., P.A. Haye, S. Tyler, M.K. Litvaitis, and I. Kornfield. 2002. Molecular systematics of the Acoela (Acoelomorpha, Platyhelminthes) and its concordance with morphology. Molec. Phylog. Evol. 24: 333-342
Pfistermüller, R., and S. Tyler (2002) Spermatozoa and spermatogenesis in Genostoma kozloffi (Plathelminthes, Rhabdocoela). Zoomorphology 121:149--158.
Pfistermüller, R., and Tyler, S. (2002) Correlation of fluorescence and electron microscopy of F-actin-containing sensory cells in the epidermis of Convoluta pulchra (Platyhelminthes, Acoela). Acta Zoologica 83:15--24.
Tyler, S., and M.D. Hooge (2001). Musculature of Gnathostomula armata Riedl 1971 and its ecological significance. PSZN Marine Ecology 21:71-83.
Hooge, M.D., and S. Tyler (2001). Interstitial acoels (Platyhelminthes, Acoela) from Bermuda. Proc. Biol. Soc. Wash. 114: 414-426.
Tyler, S. (2001) The early worm---origins and relationships of the lower flatworms. In: Littlewood DTJ, Bray R (eds) Interrelationships of the Platyhelminthes, London: Taylor & Francis, pp 3-12
Tyler, S. and R. M. Rieger (1999) Functional morphology of musculature in the acoelomate worm Convoluta pulchra (Platyhelminthes). Zoomorphology 119: 127-141
Hooge M.D. and S. Tyler (1999) Musculature of the facultative parasite Urastoma cyprinae (Platyhelminthes). J. Morphology 241:207-216
Tyler, S. (1999) Platyhelminthes. In: Encyclopedia of Reproduction, E. Knobil & J.D. Neill, eds. Academic Press, San Diego, Vol. 3, pp 901-908
Tyler, S. (1999) Systematics of the flatworms---Libbie Hyman's influence on current views of the Platyhelminthes. Am. Mus. Novitates No. 3277, pp 52-66.
Tyler, S., and M.S. Tyler (1997) Origin of the epidermis in parasitic platyhelminths. Internat. J. Parasitol. 27:715-738.
Rieger, R.M., S. Tyler, G.E. Rieger, and J.P.S. Smith (1991) Turbellaria. In Microscopic Anatomy of Invertebrates, Volume 3, Platyhelminthes and Nemertinea, F.W. Harrison and B.J. Bogitsh (eds), Wiley-Liss, New York. pp. 7-140.
Tyler, S., ed. (1991) Turbellarian Biology. Dr. W. Junk Publ., Dordrecht, The Netherlands. 398 pp.
Adjunct Faculty
Pollination ecology, native bee conservation, air quality monitoring using lichens
Pollination ecology, native bee conservation, air quality monitoring using lichens
Cooperating Faculty
Marine algae: developmental biology and physiology of fertilization; marine ecology; environmental control of reproduction
Marine algae: developmental biology and physiology of fertilization; marine ecology; environmental control of reproduction
Nutrition: Pesticide detection, natural toxicants
Nutrition: Pesticide detection, natural toxicants
Natural toxicants and pesticides in food
Analytical methods development of chemical constituents in food
Pesticide movement in groundwater
Natural toxicant levels in organic fruits, vegetables and milk
Integrated pest management of vegetable and small fruit crops
Integrated pest management of vegetable and small fruit crops
Mathematical population ecology, complex adaptive systems, modeling
Mathematical population ecology, complex adaptive systems, modeling
My research and outreach activities are mainly done through my SPEED Lab group (Spatial Population Ecological and Epidemiological Dynamics); links to various information about my teaching, research, etc. should be over on the left (or possibly at the bottom of the page if your browser doesn't do CSS). If you are a student interested in working with me, please contact me. I try to have students (undergraduate and graduate) involved in my research group as much as possible.
Molecular genetics of growth and development, genome flux
Molecular genetics of growth and development, genome flux
Population biology, speciation theory, molecular systematics
Population biology, speciation theory, molecular systematics
Plant Science: Molecular biology of host-pathogen interactions; diseases of horticultural crops
Plant Science: Molecular biology of host-pathogen interactions; diseases of horticultural crops
Plant physiology: disease, ectomycorrhizal, and ethylene effects on growth of conifers
Plant physiology: disease, ectomycorrhizal, and ethylene effects on growth of conifers
Quantitative and population genetics of marine invertebrates, molecular evolution
Quantitative and population genetics of marine invertebrates, molecular evolution
Behavioral neuroscience, chronobiology, and animal models of psychiatric disorder
Behavioral neuroscience, chronobiology, and animal models of psychiatric disorder
Ecological physiology of marine invertebrates; biology of symbiotic cnidarians; UV photobiology and oxidative stress
Ecological physiology of marine invertebrates; biology of symbiotic cnidarians; UV photobiology and oxidative stress
Biological and environmental influences on forest health and productivity
Biological and environmental influences on forest health and productivity
My research is focused on three areas:
1. wood-destroying diseases initiated by wounds and tree response to limit the spread of wood-destroying infections following wounding,
2. the use of dendrochemical markers to detect and date major changes in root-zone chemistry related to acid deposition and other environmental perturbations
3. the role of wood-destroying fungi in the biogeochemical cycling of calcium, a key element for regulating stability of the forest ecosystem
Ecology and evolutionary biology of benthic marine algae, invertebrates, and communities; emphasis on crustose coralline algae, herbivores, and lobster
Ecology and evolutionary biology of benthic marine algae, invertebrates, and communities; emphasis on crustose coralline algae, herbivores, and lobster
Environmental toxicology: molecular mechanisms of carcinogenesis, comparative carcinogenesis, aquatic toxicology
Environmental toxicology: molecular mechanisms of carcinogenesis, comparative carcinogenesis, aquatic toxicology
Recent Emeriti & Retired Faculty
Plant systematics, molecular phylogeny, reproductive biology, and quantitative morphology
Plant systematics, molecular phylogeny, reproductive biology, and quantitative morphology
I study plant systematics, reproductive biology, and phylogeny, with special emphasis on the Rosaceae (the rose family) and Pinaceae (the pine family). Along with collaborators, I am interested in the molecular phylogeny of these families based on sequences from multiple genes. Current focus is on one of the genera of the rose family, Amelanchier (the shadbushes or serviceberries), which has long challenged systematists with its unclear species boundaries and complex patterns of morphological variation. These small trees and shrubs also provide a model for the evolution of apomixis (asexual seed production). Research goals include identifying the relevance of apomixis and polyploidy to patterns of variation, understanding the biology of apomixis, establishing a workable species concept, and developing a tractable species classification. We are also involved in working out the tree of life for the Pinaceae and related plants. Research techniques include field studies, DNA sequencing, phylogenetic analyses, quantitative morphology, and studies of breeding systems. Graduate students I have advised have used these techniques to study problems in these groups and other groups as well.
Havill, N.P., C.S. Campbell, T.F. Vining, B. LePage, R. J. Bayer, and M.J. Donoghue. 2008. Phylogeny and biogeography of Tsuga (Pinaceae) inferred from nuclear ribosomal DNA ITS and chloroplast DNA sequence variation. Systematic Botany 33:478-489. MAFES ext. pub. 3008.
Campbell, C., R. Evans, D.R. Morgan, T.A. Dickinson, and M. Arsenault. Phylogeny of Pyrinae (Rosaceae): 2007. Limited resolution of a complex evolutionary history. Plant Systematics and Evolution 266:119-145. MAFES ext. pub. 2894.
Potter, D., T. Eriksson, R. Evans, S.-H. Oh, and J. Smedmark, D. Morgan, M. Kerr, K. Robertson, M. Arsenault, and C. Campbell. 2007. Rosaceae phylogeny and classification. Plant Systematics and Evolution 266:5-43. MAFES ext. pub. 2895.
Campbell, C. R. Evans, D.R. Morgan, T.A. Dickinson, and M. Arsenault. Phylogeny of Pyrinae (Rosaceae): 2007. Limited resolution of a complex evolutionary history. Plant Systematics and Evolution, in press.
Campbell, C.S., W. A. Wright, M. Cox, , and T.F Vining, C.S. Major, and M.P. Arsenault. 2005. Internal transcribed spacer 1 (ITS1) in Picea (Pinaceae): secondary structure and phylogeny. Molecular Phylogenetics and Evolution 35:165-185. MAFES ext. pub. 2770.
Hilu K. W., T. Borsch, K. Maller, D. E. Soltis, P. S. Soltis, V. Savolainen, M. W. Chase, M. Powell, L. A. Alice, R. C. Evans, H. Sauquet, C. Neinhuis, T. A. Slotta, J. G. Rohwer, C. S. Campbell, and L. Chatrou. 2003. Angiosperm phylogeny based on matK sequence information. American Journal of Botany 90:1758-1776.
Smedmark, J. E. E., Eriksson, T., Evans, R. C., Campbell, C. S. 2003. Ancient Allopolyploid Speciation in Geinae (Rosaceae): Evidence from Nuclear Granule-Bound Starch Synthase (GBSSI) Gene Sequences. Syst. Biol. 52: 374-385.
Liston, A., Gernandt, D.S., Vining, T.F., Campbell, C.S. and Pinero, D. 2003. Molecular phylogeny of Pinaceae and Pinus. Acta Horticulturae (ISHS) 615:107-114. http://www.actahort.org/books/615/615_7.htm.
Judd, W.S., C.S. Campbell, E.A. Kellogg, P.F. Stevens, and M.J. Donoghue. 2002. Plant systematics. A phylogenetic approach. (An introductory textbook, Second ed. The third ed. is due out in 2007). Sinauer Associates, Sunderland, MA.
Evans, R.C. and C.S. Campbell. 2002. The Origin of the apple subfamily (Rosaceae: Maloideae) is clarified by DNA sequence data from duplicated GBSSI Genes. American Journal of Botany 89:1478-1484. Maine Agricultural and Forest Experiment Station external publication 2530.
Alice, L. A., T. Eriksson, B. Eriksen, and C. S. Campbell. 2001. Intersubgeneric hybridization in Rubus (Rosaceae). Systematic Botany 26:769-778.
Evans, R.C., L.A. Alice, C. S. Campbell, E. A. Kellogg, and T.A. Dickinson. 2000. The granule-bound starch synthase (GBSSI) gene in Rosaceae: multiple putative loci and phylogenetic utility. Molecular Phylogenetics and Evolution 17:388-400. MAFES ext. pub. 2430.
Campbell, C.S., L.A. Alice, and W.A. Wright. 1999. Comparisons of within-population genetic variation in sexual and agamospermous Amelanchier (Rosaceae) using RAPD markers. Plant Systematics and Evolution 215:157-167.
Alice, L.A. and C. S. Campbell. 1999. Phylogeny of Rubus (Rosaceae) based on nuclear ribosomal DNA internal transcribed spacer sequences. American Journal of Botany 86:81-97.
Campbell, C.S. 1999. The evolutionary role of hybridization in agamic complexes, with special emphasis on Amelanchier (Rosaceae). In L.W.D. van Raamsdonk J.C.M. den Nijs (eds.). Plant evolution in man-made habitats. Proceedings of the VIIth International Symposium of the International Organization of Plant Biosystematists. MAFES ext. publ. 2332.
Genetic and molecular analysis of cardiac pacemakers; biology of cellular oscillators; mathematical analysis and modeling of biological systems
Genetic and molecular analysis of cardiac pacemakers; biology of cellular oscillators; mathematical analysis and modeling of biological systems
I am a comparative physiologist with a background in mathematics and genetics.
Molecular Mechanisms in Cardiac Physiology
I am investigating cardiac function at the cellular level in Drosophila melanogaster using molecular, genetic, and pharmacological tools. The heart of this organism makes an ideal model for probing the way in which heartbeat is generated. We have discovered a number of mutations which render the heart arrhythmic, and probing the way in which these lesions affect the beat yields information on the ion channels constituting this electrochemical pacemaker. We use neurotransmitters and ion channel specific toxins to alter function. I have cloned a calcium channel central to the pacemaker and am expressing this channel in Xenopus oocytes to determine its characteristics. This three-pronged approach yields a clearer picture of the self-sustained oscillation driving the heart. Owing to homologies among ion channels in the mammalian and insect heart, we expect to shed light on the latter's more complicated system with this model.
Digital Signal Analysis
In my work with circadian rhythms and heartbeat, I have adapted a number of digital signal analysis techniques for use with biological systems. One of these techniques is Maximum Entropy Spectral Analysis. More recently, I have adapted wavelet analysis techniques for use in circadian rhythms. I am currently investigating acoustic signals produced by male Drosophila during courtship. There is a great deal of species-specific information carried by these songs. I have adapted wavelet decomposition techniques for time-frequency of analysis of these signals as well. Wavelet analysis is a new method that holds promise for other biological signals, including heartbeat.
Circadian Rhythms
I continue my work on circadian and ultradian rhythms in collaboration with investigators at other institutions, principally Brandeis University. I am particularly interested in ultradian rhythms and their potential role underlying the 24-h oscillator, and have worked on the role of the cry gene in peripheral clocks and social interactions that can lead to resetting of the clock.
Dowse, H., J. Umemori, and T. Koide. 2010. Ultradian Components in the Locomotor Activity Rhythms of the Genetically Normal Mouse, Mus musculus. J. Exp. Biol., 213: 1788-1795.
Jennings, T., J. Ringo and H. Dowse. 2009. The relationship of heart function to temperature in Drosophila melanogaster and its heritability. J Exp. Zool. 311A: 689-696.
Dowse, H.B. 2008. Mid-range ultradian rhythms in Drosophila and the circadian clock problem. In: D.L. Lloyd, and E. Rossi (eds.) Ultradian Rhythms from Molecules to Mind: A New Vision of Life. Springer Verlag.
Gaten E., Tarling, G., Dowse, H., Kyriacou, C. and Rosato, E. 2008. Is vertical migration in Antarctic krill (Euphausia superba) influenced by an underlying circadian rhythm? J. Genetics, 87: 473-483.
Dowse, H. 2007. Statistical analysis of biological rhythm data. Methods in Molecular Biology: Circadian Rhythms. E. Rosato, ed. 362:29-45. Humana Press.
Ray, V. and H. Dowse. 2005. Mutations in the Ca2+ channel-encoding gene cacophony, which affect courtship song in Drosophila, have novel effects on heartbeating. Journal of Neurogenetics 19: 39-56.
Sanyal, S., T. Jennings, H. Dowse, and M. Ramaswami. 2005. Conditional mutations in SERCA, the Sarco-endoplasmic reticulum Ca2+-ATPase, alter heart rate and rhythmicity in Drosophila. Journal of Comparative Physiology B. 176: 253-263.
Plant ecology and paleoecology; long-term history and dynamics of vegetation and climate in the Western Hemisphere
Plant ecology and paleoecology; long-term history and dynamics of vegetation and climate in the Western Hemisphere
My scientific focus involves past and present patterns in vegetation, and particularly the nature of climatic and ecological changes that have shaped modern landscapes. This research has two broad themes: patterns of modern vegetation, and changes in vegetation through time. Recent projects involving modern vegetation have dealt with forests, peatlands, and saltmarshes of Maine. These studies, which seek to describe and explain the distribution of plants in these ecosystems, have included analysis of local and regional patterns in vegetation with special emphasis on how spatial and temporal variations in climate, geology, disturbance, and other factors have affected the plant assemblages. Current paleoecological studies involve sites in Maine, as well as in northern New England, Florida, Sweden, and Chile. This research is designed to provide understanding of long-term ecosystem processes, many of which are not evident on modern landscapes or within human life-spans. The projects usually involve analysis of plant fossils that have accumulated in lakes and bogs over thousands of years, and have as a primary focus the responses of vegetation to abrupt climate changes of the past.
See also Climate Change Institute.
Biochemical characterization of wood decay; metal metabolism in fungi; fungal physiology; bioremediation
Biochemical characterization of wood decay; metal metabolism in fungi; fungal physiology; bioremediation
Our current research focuses on the biodegradation of woody plant cell walls by brown- and white-rot fungi. Areas of interest include: Free radical production in biological systems, monoclonal antibody production to extracellular enzymes; siderophore production by fungi; the role of transition metals in biodegradation and fungal metabolism; immunodetection of plant pathogens; electron microscopy; cation mobilization and fungal colonization; PCR detection of degradative fungi; cation translocation by fungi in the forest ecosystem and fungal bioremediation of toxic materials.
Genetic analysis of reproductive behavior and cardiac rhythms
Genetic analysis of reproductive behavior and cardiac rhythms
My research area is the genetics of behavior, using Drosophila as the experimental organism. I am currently using genetics and pharmacology to investigate two separate phenomena, cardiac rhythmns and female receptivity.
Heart rhythms
Cardiac rhythms of Drosophila originate in a myogenic pacemaker. My collaborator, Dr. Harold Dowse (this Department) and I have identified two ion channels central to this pacemaker: A voltage-gated "OPQ-Type" Calcium channel, and a fast Calcium-gated potassium channel encoded by the slowpoke gene. Other Potassium channels may be involved, but sodium channels do not play a role in heartbeat. We have found several mutants with severe cardiac arrhythmias: slowpoke, no-action-potential, amnesiac, Dopa decarboxylase, and ether-a-go-go. We have also found that serotonin, octopamine, norepinephrine, dopamine, and acetylcholine are cardioacceleratory, while a pentapeptide from Limulus slows heartbeat.
Female sexual receptivity
Receptivity is switched on in young adults. I am studying the genetic and endocrine program underlying the switch-on, using a combination of genetic, physiological, and ethological approaches. A few genes are known to be crucial to receptivity; I am utilizing two, apterous (ap) and icebox. apterous mutants are deficient in JH, and therefore develop receptivity very slowly. icebox, discovered to be a behavioral mutation in this lab, exerts a stronger effect on receptivity than any other known gene. I also use JH analogs and JH inhibitors in these studies. I characterize the "microresponses" of females---the frequency and details of their signals to sexually active males---by analyzing videotaped behavior.
Biology of Frankia, a nitrogen-fixing actinomycete, and physiological plant ecology with emphasis on nitrogen fixing and wetland plants
Biology of Frankia, a nitrogen-fixing actinomycete, and physiological plant ecology with emphasis on nitrogen fixing and wetland plants
My main research interests lie at the interface between physiology of plants and the kinds of environments in which they occur. Topics that are of special interest to me include the physiological ecology of actinorhizal nitrogen-fixing plants, physiological ecology of peatland plants, plant energy budgets, and physiological ecology of seed germination.
Most of my current work concerns the physiology and ecology of actinorhizal plants. These plants are woody dicots that form nitrogen-fixing root nodules with Frankia, an actinomycete. They are found in 23 genera in 8 families and include alders (Alnus spp.), sweet gale (Myrica gale), bayberry (Myrica pensylvanica), and sweet fern (Comptonia peregrina). Actinorhizal plants commonly grow vigorously in nitrogen-poor soils where most plants grow only poorly or not at all. Such soils include raw mineral soils, sandy soils found on glacial outwash plains and along shores, and wet soils along streams and shores and in swamps and peatlands.
Presently we are examining the role that hemoglobin plays in Frankia including its localization within the cell and its interaction with oxygen. In addition we are examining the conditions needed for seedling establishment in common Maine actinorhizal plants.
Coats, V., C.R. Schwintzer, and J.D. Tjepkema. 2009. Truncated hemoglobins in Frankia CcI3: effects of nitrogen source, oxygen concentration, and nitric oxide. Canadian Journal of Microbiology 55: 867-873.
Schultz, H.S., R. Manley, W. Halteman, M.S. Erich, C.R. Schwintzer, and C. Stubbs. 2007. Effects of kaolin particle film on viburnum leaf beetle during container production of Viburnum dentatum under different levels of nitrogen fertilization. Journal of Environmental Horticulture 25: 4-8.
Silvester, W.B., R.H. Berg, C.R. Schwintzer, and J.D. Tjepkema. 2005. Oxygen responses, hemoglobin, and the structure and function of vesicles. In: K. Pawlowski (ed.), Actinorhizal Symbioses. Kluwer Academic Publishers.
Schwintzer, C.R. and J.D. Tjepkema. 2005. Effect of oxygen concentration on growth and hemoglobin production in Frankia. Symbiosis 39: 77-82.
Tjepkema, J.D., Cashon, R.E., Beckwith, J., and Schwintzer, C.R. 2002. Hemoglobin in Frankia, a nitrogen-fixing actinomycete. Applied and Environmental Microbiology 68: 2629-2631.
Schwintzer, C.R. and Tjepkema, J.D. 2001. Effect of elevated carbon dioxide in the root atmosphere on nitrogenase activity in three actinorhizal plants. Canadian Journal of Botany 79: 1010-1018.
Tjepkema, J.D., Schwintzer, C.R., Burris, R.H., Johnson, G.V., and Silvester, W.B. 2000. Natural abundance of 15N in actinorhizal plants and nodules. Plant and Soil 219: 285-289.
Dow, M.A. and Schwintzer, C.R. 1999. Seed germination, seedling emergence, and seed bank ecology of sweet-fern (Comptonia peregrina (L.) Coult.). Canadian Journal of Botany 77: 1378-1386.
Barkmann, J. and Schwintzer, C.R. 1998. Rapid N2 Fixation in Pines? - Results of a Maine Field Study. Ecology 79: 1453-1457.
Hurd, T.M. and Schwintzer, C.R. 1997. Formation of cluster roots and mycorrhizal status of Comptonia peregrina and Myrica pensylvanica in Maine, U.S.A. Physiologia Plantarum 99: 680-689.
Schwintzer, C.R. and Tjepkema, J.D. 1997. Field nodules of Alnus incana ssp. rugosa and Myrica gale exhibit pronounced acetylene-induced declines in nitrogenase activity. Canadian Journal of Botany 75: 1415-1423.
Bartsch, I. and Schwintzer, C.R. 1994. Growth of Chamaedaphne calyculata at two peatland sites in relation to nutrient availability. Wetlands 14: 147-158.
Schwintzer, C.R. and J.D. Tjepkema. 1994. Factors affecting the acetylene-to-15N2 conversion ratio in root nodules of Myrica gale L. Plant Physiology 106: 1041-1047.
Schwintzer, Christa R. and John D. Tjepkema (eds). 1990. The Biology of Frankia and Actinorhizal Plants. Academic Press, New York, 389 pp.
Pollination ecology, lichenology, mycology
Pollination ecology, lichenology, mycology
My current pollination research includes the effects of invasive plants on native pollinator foraging behavior on native plants in Acadia National Park, the overwintering potential of queen bumblebees in the lowbush blueberry agroecosystem, the effects of clearcutting and herbicides on native bees and other Hymenoptera in Maine, and conservation of native bees. Other areas of research interests include the effects of management practices on the incidence and severity of fungal pathogens of lowbush blueberry, lichen-invertebrate interactions (e. g. dispersal of lichens by insects; lichens serving as shelter and food), and lichen health on red spruce along an air pollution gradient.
Molecular genetics of virulence in plant pathogenic fungi; biological control of fungal plant pathogens
Molecular genetics of virulence in plant pathogenic fungi; biological control of fungal plant pathogens
Molecular genetics of hypovirulence in plant pathogenic fungi; functional genomics for identification and characterization of genes involved in regulation of virulence in the basidiomycete Rhizoctonia solani.
The long-term goal of my work is the biological control of a cosmopolitan, soil-borne plant pathogen, Rhizoctonia solani.
Species of Rhizoctonia cause economically important diseases on most of the world's major field and vegetable crops, fruit and forest trees, turfgrasses, and ornamental plants. Thus, characterization of genetic factors regulating virulence in R. solani could have a significant impact on a wide spectrum of plant related human endeavor.
My research group has shown that particular double-stranded RNA (dsRNA) genetic elements are associated with a dramatically decreased disease-producing capacity (e.g., hypovirulence) in R. solani. Sequencing analysis of these dsRNA's suggested that they carry an RNA polymerase gene which allows them to replicate in the host cell, but most importantly they carry nucleotide sequences that are genetically related to genes involved in different metabolic pathways. Sequencing analysis of a hypovirulence-associated dsRNA (M2) has enabled me to put forward the following hypothesis: The M2 dsRNA down-regulates the shikimic acid (shikimate) pathway, which is responsible for the synthesis of the aromatic amino acids (AAA). R. solani produces a "toxin" (phenyl acetic acid, PAA) associated with the rhizoctonia disease syndrome in potato. PAA is a derivative of one of the AAA, phenylalanine. Thus, down-regulation of AAA biosynthesis leads to a decreased production of PAA and, in turn, to a diminished degree of pathogenicity (hypovirulence).
It appears that dsRNAs in fungi (and in other organisms) are involved in gene regulation of the host cell. My research program revolves around this hypothesis. Knowledge gained in this area will lead to the development of biocontrol-based strategies of plant disease management that will fulfill the need for sustainable and nonpolluting agricultural practices. Our project is part of a multifaceted, worldwide effort aimed at making agriculture more sustainable, and congruent with the ever-growing societal aspiration to nurture the environment in which we live.
Larkin, R. P., and S. M. Tavantzis. 2013. Use of Biocontrol Organisms and Compost Amendments for Improved Control of Soilborne Diseases and Increased Potato Production. American Journal of Potato Research 90(3): 261 – 270.
Bernard, E., Larkin, R. P., Tavantzis, S. M., Erich, M. S., Alyokhin, A., Sewell, G., Lannan, A., and S. D. Gross. 2012. Compost, rapeseed rotation, and biocontrol agents significantly impact soil microbial communities in organic and conventional potato production systems. Applied Soil Ecology 52: 29 – 41
Rioux, R., Manmathan, H., Singh, P., De los Reyes, B. G., Jia, Y., and S. M. Tavantzis. 2011. Comparative analysis of putative pathogenesis-related gene expression in two Rhizoctonia solani pathosystems. Current Genetics 57: 391 – 408.
Charlton, N. D., Carbone, I., Tavantzis, S. M., and M. A. Cubeta. 2008 Phylogenetic relatedness of the M2 doube-stranded RNA in Rhizoctonia fungi. Mycologia 100:555-564.
Tavantzis, S. M. 2008. Partiviruses of Fungi. In "Encyclopedia of Virology" 3rd Edition, Vol. 4, pp. 63-68. B. W. V. Mahy, M. H. V. Van Regenmortel, Eds. Elsevier, Ltd. & Academic Press, San Diego, CA., U.S.A.
Charlton, N. D., Tavantzis, S. M., and Cubeta, M. A. 2007. Detection of Double-stranded RNA Elements in Plant Pathogenic Fungi. In "Plant Pathology Techniques and Procedures", Chapter 14, pp. 171-182. Burns R., Ed. Humana Press, 2nd Edition, Tocawa, NJ, USA.
Lakshman, D. K, Liu, C., Mishra, P. and Tavantzis, S. M. 2006. Characterization of the arom gene in Rhizoctonia solani, and transcription patterns under stable and induced hypovirulence conditions. Current Genetics 49: 166 – 177
Liu C., Lakshman D. K., Tavantzis S. M. 2003. Quinic acid induces hypovirulence, and expression of a hypovirulence-associated double-stranded RNA in Rhizoctonia solani. Current Genetics 43:103-111
Liu C., Lakshman D. K., Tavantzis S. M. 2003. Expression of a hypovirulence-causing double-stranded RNA (dsRNA) is associated with up-regulation of quinic acid pathway, and down-regulation of shikimic acid pathway in Rhizoctonia solani. Current Genetics 42:284-291
Tavantzis, S. M. 2001. dsRNA genetic elements: Concepts and applications in Agriculture, Forestry and Medicine. 304 p. CRC Press LLC, Boca Raton, FL.
Tavantzis, S. M., Lakshman, D. K. and Liu, C. 2001. Double-stranded RNA Elements Modulating Virulence in Rhizoctonia solani in DsRNA Genetic Elements: Concepts and Applications in Agriculture, Forestry, and Medicine, pp. 191-201. Ed. S. M. Tavantzis, 304 p.CRC Press LLC.
Strauss, E. E., Lakshman, D. K., and Tavantzis, S. M. 2000. Molecular characterization of the genome of a partitivirus from the basidiomycete Rhizoctonia solani. Journal of General Virology 81:549-555.
Jian, J., Lakshman, D. K., and S. M. Tavantzis. 1998. A virulence-associated 6.4-kb dsRNA from Rhizoctonia solani is phylogenetically related to plant bromoviruses and electron transport enzymes. Molecular Plant-Microbe Interactions 11:601-609.
Lakshman, D. K., Jian, J., and Tavantzis, S. M. 1998. A novel mitochondrial double-stranded RNA found in a hypovirulent strain of Rhizoctonia solani occurs in DNA form, and is phylogenetically related to the pentafunctional AROM protein of the shikimate pathway. Proceedings of the National Academy of Sciences (USA) 95:6425-6429 .
Jian, J., Lakshman D. K., and Tavantzis, S. M. 1997. Association of distinct double-stranded RNAs with enhanced or diminished virulence in Rhizoctonia solani infecting potato. Molecular Plant-Microbe Interactions 10:1002-1009.
Rubio, V., Tavantzis, S. M., and Lakshman, D. K. 1996. Extrachromosomal elements and degree of pathogenicity in Rhizoctonia solani. In \"Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control\", pp.127-138. B. Sneh, S. Jabaji-Hare, S. Neate and G. Dijst, Eds., 578 p. Kluwer Academic Publishers, Dordrecht, The Netherlands.
Tavantzis, S. M., and D. K. Lakshman. 1995. Virus-like double-stranded RNA elements and hypovirulence in phytopathogenic fungi. Vol. III, Chapter 17, pp. 249-267. In Pathogenesis and Host-Parasite Specificity in plant Diseases: Histopathological, Biochemical, Genetic and Molecular Bases, Vol. III: Viruses and Viroids. K. Kohmoto, R. P. Singh, and U. S. Singh Eds. Elsevier (Pergamon) Press, Oxford, UK.
Castello, J. D., D. K. Lakshman, S. M. Tavantzis, S. O. Rogers, G. D. Bachand, R. Jagels, and J. Carlisle. 1995. Detection of infectious tomato mosaic virus in fog and clouds. Phytopathology 85: 1409-1411.
Tavantzis, S. M., and D. K. Lakshman. 1995. Virus-like double-stranded RNA elements and hypovirulence in phytopathogenic fungi. Vol. III, Chapter 17, pp. 249-267. In \"Pathogenesis and Host-Parasite Specificity in plant Diseases: Histopathological, Biochemical, Genetic and Molecular Bases, Vol. III: Viruses and Viroids\". K. Kohmoto, R. P. Singh, and U. S. Singh Eds. Elsevier (Pergamon) Press, Oxford, UK.
Lakshman, D. K. and S. M. Tavantzis. Spontaneous appearance of genetically distinct dsRNA elements in Rhizoctonia solani. 1994. Phytopathology 84: 633-639.
Singh, R. P., A. Boucher, D. K. Lakshman, and S. M. Tavantzis. 1994. Multimeric non-radioactive cRNA probes improve detection of potato spindle tuber viroid (PSTV). Journal of Virological Methods 49: 221-234.
Tavantzis, S. M. 1994. Double-stranded RNA-associated cytoplasmic hypovirulence in Rhizoctonia solani: Prospects for developing a reliable, target-specific biocontrol system. pp. 565-579. In \"Advances in Potato Pest Biology and Management. G. W. Zehnder, M. L. Powelson, R. K. Jansson, and K. V. Raman, Eds. APS Press, St. Paul, MN.
Lakshman, K. D. and Tavantzis, S. M.. 1993. Primary and secondary structure of a 360-nucleotide isolate of potato spindle tuber viroid. Archives of Virology 128: 319-332.
Singh, R. P., Lakshman, D. K., Boucher, A., and Tavantzis, S. M. 1992. A viroid from Nemantanthus wettsteineii plants closely related to Columnea latent viroid. J. Gen. Virology 73: 2769-2774.
Lakshman, D., Tavantzis, S. M., Boucher, A., and Singh, R. P. 1992. A rapid and versatile method for cloning viroids or other circular plant pathogenic RNA\'s. Analytical Biochemistry 203: 269-273.
Lakshman, K. D. and S. M. Tavantzis. 1992. RNA progeny of an infectious two-base deletion cDNA mutant of the potato spindle tuber viroid acquire two nucleotides in planta. Virology 187: 565-572.
Tavantzis, S. M. 1991. In vitro translation of potato carlavirus M RNA: coat protein and protease activity as translation products of virion-associated RNA. Archives of Virology 120: 241-252.
Bharathan, N. and Tavantzis, S. M. 1991. Assessment of genetic relatedness among double-stranded RNA components from Rhizoctonia solani isolates of diverse geographic origin. Phytopathology 81: 411-415.
Tavantzis, S. M. 1990. Outlook on the molecular biology of virus resistance in potato, p.113-135. In \"The Molecular Biology of Potato\", M. E. Vayda & W. D. Park, eds. C.A.B. International, Wallingford, U.K.
Bharathan, N., and Tavantzis, S. M. 1990. Genetic diversity of double-stranded RNAs in Rhizoctonia solani. Phytopathology 80: 631-635.
Tavantzis, S. M. 1990. Outlook on the molecular biology of virus resistance in potato, p.113-135. In "The Molecular Biology of Potato", M. E. Vayda & W. D. Park, eds. C.A.B. International, Wallingford, U.K.
Frey, M., Tavantzis, S. M. and Saedler, H. 1989. The maize En/Spm element transposes in potato. Molecular and General Genetics 217: 172-177.
Tavantzis, S. M. 1988. Biological control of Rhizoctonia disease and increased growth response of potato effected by hypovirulent R. solani. pp. 44-46, in \"Innovations in Pest Management\" ed. by S. Engelstad, W.M. Coli, & J. L. Carlson. 75 p., U. Mass. Press.
Tavantzis, S. M. and B. P. Bandy. 1988. Properties of a mycovirus from Rhizoctonia solani and its virion-associated RNA polymerase. Journal of General Virology 69: 1465-1477.
Tavantzis, S. M. 1988. Biological control of Rhizoctonia disease and increased growth response of potato effected by hypovirulent R. solani. pp. 44-46, in \"Innovations in Pest Management\" ed. by S. Engelstad, W.M. Coli, & J. L. Carlson. 75 p., U. Mass. Press.
Hoch, J. G., Tavantzis, S. M., Campana, R. J., and Anagnostakis, S. L. 1985. Evaluation of the presence of double-stranded RNA in Ceratocystis ulmi. Can. J. Botany 63:297-300.
Tavantzis, S. M. 1984. Physicochemical properties of potato virus M. Virology 133:427-430.
Bandy, B. P., Zanzinger, D. H., and Tavantzis, S. M. 1984. Anastomosis group 5 of Rhizoctonia solani Kuhn isolated from potato-cultivated soils in Maine. Phytopathology 74:1220-1224.
Zanzinger, D. H., Bandy, B. P., and Tavantzis, S. M. 1984. High frequency of finding double-stranded RNA in naturally occurring isolates of Rhizoctonia solani. J. Gen. Virol. 65:1601-1605.
Tavantzis, S. M. 1983. State of development of leaf and tuber tissue in potato influences the titer of potato virus M. Am. Potato J. 69:99-108.
Tavantzis, S. M. 1983. Improved purification of two potato carlaviruses. Phytopathology 73:190-194.
Tavantzis, S. M., Romaine, C. P. and Smith, S. H. 1983. Mechanism of genome expression in a single-stranded RNA virus from the cultivated mushroom [Agaricus bisporus (Lange) Imbach.]. Phytopath. Z. 106:45-50.
Tavantzis, S. M. and Southard, S. G. 1983. Incidence of potato virus X in seed potatoes of seven cultivars. Plant Disease 67:959-961.
Tavantzis, S. M. and Smith, S. H.. 1982. Isolation and evaluation of a plant-virus-inhibition quinone from sporophores of Agaricus bisporus. Phytopathology 72:619-621.
Tavantzis, S. M., Romaine, C. P., and Smith, S. H. 1980. Purification and partial characterization of a bacilliform virus from Agaricus bisporus: A single-stranded RNA mycovirus. Virology 105:94-102.
Tavantzis, S. M., Smith, S. H. and Witham, F. H. 1979. The influence of kinetin on tobacco ringspot virus infectivity and the effect of virus infection on the cytokinin activity in intact leaves of Nicotiana glutinosa L. Physiological Plant Pathology. 14:227-233.
Tavantzis, S. M. and Smith, S. H. 1979. Virus-like particles transmitted by and detected in spawn of Agaricus bisporus. Phytopathology 69:104-107.
Whole-plant physiology; physiology and ecology of nitrogen fixation
Whole-plant physiology; physiology and ecology of nitrogen fixation
I am especially interested in the physiology and ecology of nitrogen fixation, and other aspects of the nitrogen cycle. I am currently studying actinorhizal nodules such as those of alders, where the nitrogen-fixing symbiont is an actinomycete (Frankia). There are 23 genera of dicots, in 8 families, that form actinorhizal nodules. These plants are important in forestry, land reclamation, and the global nitrogen budget.
My work with actinorhizal nodules concerns the regulation of gas exchange and the function of nodule hemoglobins. These hemoglobins are similar to the myoglobins of animal muscle tissue, but their function is unknown. I have shown that hemoglobins are present in high concentrations in the nodules of some actinorhizal species, and in low concentrations in other species. My working hypothesis is that hemoglobins are needed for the extremely high rates of respiration and gas exchange that occur in root nodules. We have recently shown that Frankia produces hemoglobin when grown in pure culture. Current research focuses on the establishing the function of this hemoglobin, both in the free-living and symbiotic states of Frankia.
Marine and algal ecology; recruitment; plant-herbivore and predator-prey interactions
Marine and algal ecology; recruitment; plant-herbivore and predator-prey interactions
My interests span a wide range of intertidal and subtidal ecological questions. Students are encouraged to work in areas related to ongoing projects but flexibility is allowed in the selection of thesis projects. New students are encouraged to spend time in the field because many ecological problems can be addressed only with a solid understanding of natural history. Students are strongly encouraged to develop a strong inference approach to ecological questions. This often involves experimental manipulations based on sound experimental designs.
My major foci at present are on recruitment and ecology of fucoid algae, especially Ascophyllum nodosum, and on the growth and reproductive ecology of green sea urchins. The alga is long-lived and the dominant intertidal alga throughout much of the North Atlantic ocean. Studies are directed towards understanding the mechanisms of attachment and the role of recruitment and dispersal on population regulation. Sea urchins are the second major marine resource in Maine. However, overharvesting created a boom and bust phenomenon, and understanding growth and reproductive processes may be crucial to recovery. Aspects of algal-herbivore interactions, including foraging behavior of invertebrates and their influence on the structure of intertidal assemblages, continue to be a component of my work. Behavioral studies on herbivores are an important but somewhat neglected aspect of community studies.