Turgor pressure

Turgor pressure is the force within the cell that pushes the plasma membrane against the cell wall.
It is also called "hydrostatic pressure", and defined as the pressure measured by a fluid, measured at a certain point within itself when at equilibrium. Generally, turgor pressure is caused by the osmotic flow of water and occurs in plants, fungi, and bacteria. The phenomenon is also observed in protists that have cell walls. This system is not seen in animal cells, as the absence of a cell wall would cause the cell to lyse when under too much pressure. The pressure exerted by the osmotic flow of water is called turgidity. It is caused by the osmotic flow of water through a selectively permeable membrane. Osmotic flow of water through a semipermeable membrane is when the water travels from an area with a low-solute concentration, to one with a higher-solute concentration. In plants, this entails the water moving from the low concentration solute outside the cell, into the cell's vacuole.
Mechanism.
Osmosis is the process in which water flows from an area with a low solute concentration, to an adjacent area with a higher solute concentration until equilibrium between the two areas is reached. All cells are surrounded by a lipid bi-layer cell membrane which permits the flow of water in and out of the cell while also limiting the flow of solutes. In hypertonic solutions, water flows out of the cell which decreases the cell's volume. When in a hypotonic solution, water flows into the membrane and increases the cell's volume. When in an isotonic solution, water flows in and out of the cell at an equal rate.
Turgidity is the point at which the cell's membrane pushes against the cell wall, which is when turgor pressure is high. When the cell membrane has low turgor pressure, it is flaccid. In plants, this is shown as wilted anatomical structures. This is more specifically known as plasmolysis.The volume and geometry of the cell affects the value of turgor pressure, and how it can have an effect on the cell wall's plasticity. Studies have shown how smaller cells experience a stronger elastic change when compared to larger cells.
Turgor pressure also plays a key role in plant cell growth where the cell wall undergoes irreversible expansion due to the force of turgor pressure as well as structural changes in the cell wall that alter its extensibility.
Turgor pressure in plants.
Turgor pressure within cells is regulated by osmosis and this also causes the cell wall to expand during growth. Along with size, rigidity of the cell is also caused by turgor pressure; a lower pressure results in a wilted cell or plant structure (i.e. leaf, stalk). One mechanism in plants that regulate turgor pressure is its semipermeable membrane, which only allows some solutes to travel in and out of the cell, which can also maintain a minimum amount of pressure. Other mechanisms include transpiration, which results in water loss and decreases turgidity in cells. Turgor pressure is also a large factor for nutrient transport throughout the plant. Cells of the same organism can have differing turgor pressures throughout the organism's structure. In higher plants, turgor pressure is responsible for apical growth of things such as root tips and pollen tubes.
Dispersal.
Transport proteins that pump solutes into the cell can be regulated by cell turgor pressure. Lower values allow for an increase in the pumping of solutes; which in turn increases osmotic pressure. This function is important as a plant response when under drought conditions (seeing as turgor pressure is maintained), and for cells which need to accumulate solutes (i.e. developing fruits).
Flowering and reproductive organs.
It has been recorded that the petals of "Gentiana kochiana" and "Kalanchoe blossfeldiana" bloom via volatile turgor pressure of cells on the plant's adaxial surface. During processes like anther dehiscence, it has been observed that drying endothecium cells cause an outward bending force which led to the release of pollen. This means that lower turgor pressures are observed in these structures due to the fact that they are dehydrated. Pollen tubes are cells which elongate when pollen lands on the stigma, at the carpal tip. These cells grow rather quickly due to increases turgor pressure. These cells undergo tip growth. The pollen tube of lilies can have a turgor pressure of 0–21 MPa when growing during this process.
Seed dispersal.
In fruits such as "Impatiens parviflora", "Oxalia acetosella" and "Ecballium elaterium", turgor pressure is the method by which seeds are dispersed. In "Ecballium elaterium", or squirting cucumber, turgor pressure builds up in the fruit to the point that aggressively detaches from the stalk, and seeds and water are squirted everywhere as the fruit falls to the ground. Turgor pressure within the fruit ranges from .003 to 1.0 MPa.
Growth.
Turgor pressure's actions on extensible cell walls is usually said to be the driving force of growth within the cell. An increase of turgor pressure causes expansion of cells and extension of apical cells, pollen tubes, and in other plant structures such as root tips. Cell expansion and an increase in turgor pressure is due to inward diffusion of water into the cell, and turgor pressure increases due to the increasing volume of vacuolar sap. A growing root cell's turgor pressure can be up to 0.6 MPa, which is over three times that of a car tire. Epidermal cells in a leaf can have pressures ranging from 1.5 to 2.0 MPa. As plants can operate at such high pressures, this can explain why they can grow through asphalt and other hard surfaces.
Turgidity.
Turgidity is observed in a cell where the cell membrane is pushed against the cell wall. In some plants, their cell walls loosen at a quicker rate than water can cross the membrane, which results in a cell with lower turgor pressure.
Stomata.
Turgor pressure within the stomata regulates when the stomata can open and close, which has a play in transpiration rates of the plant. This is also important because this function regulates water loss within the plant. Lower turgor pressure can mean that the cell has a low water concentration and closing the stomata would help to preserve water. High turgor pressure keeps the stomata open for gas exchanges necessary for photosynthesis.
"Mimosa pudica".
It has been concluded that loss of turgor pressure within the leaves of "Mimosa pudica" is responsible for the reaction the plant has when touched. Other factors such as changes in osmotic pressure, protoplasmic contraction and increase in cellular permeability have been observed to affect this response. It has also been recorded that turgor pressure is different in the upper and lower pulvinar cells of the plant, and the movement of potassium and calcium ions throughout the cells cause the increase in turgor pressure. When touched, the pulvinus is activated and exudes contractile proteins, which in turn increases turgor pressure and closes the leaves of the plant.
Function in other taxa.
As earlier stated, turgor pressure can be found in other organisms besides plants and can play a large role in the development, movement, and nature of said organisms.
Fungi.
In fungi, turgor pressure has been observed as a large factor in substrate penetration. In species such as "Saprolegnia ferax, Magnaporthe grisea" and "Aspergillus oryzae," immense turgor pressures have been observed in their hyphae. The study showed that they could penetrate substances like plant cells, and synthetic materials such as polyvinyl chloride. In observations of this phenomenon, it is noted that invasive hyphal growth is due to turgor pressure, along with the coenzymes secreted by the fungi to invade said substrates. Hyphal growth is directly related to turgor pressure, and growth slows as turgor pressure decreases. In "Magnaporthe grisea", pressures of up to 8 MPa have been observed.
Protists.
Some protists do not have cell walls and cannot experience turgor pressure. These few protists are ones that use their contractile vacuole to regulate the quantity of water within the cell. Protist cells avoid lysing in solutions by utilizing a vacuole which pumps water out of the cells to maintain osmotic equilibrium.
Animals.
Turgor pressure is not observed in animal cells because they lack a cell wall. In organisms with cell walls, the cell wall prevents the cell from lysing from high-pressure values.
Diatoms.
In Diatoms, the Heterokontophyta have polyphyletic turgor-resistant cell walls. Throughout these organisms' life cycle, carefully controlled turgor pressure is responsible for cell expansion and for the release of sperm, but not for things such as seta growth.
Cyanobacteria.
Gas-vaculate cyanobacterium are the ones generally responsible for water-blooms. They have the ability to float due to the accumulation of gases within their vacuole, and the role of turgor pressure and its effect on the capacity of these vacuoles has been observed in varying scientific papers. It is noted that the higher the turgor pressure, the lower the capacity of the gas-vacuoles in different cyanobacterium. Experiments used to correlate osmosis and turgor pressure in prokaryotes have been used to show how diffusion of solutes into the cell have a play on turgor pressure within the cell.
Measurements.
When measuring turgor pressure in plants, many things have to be taken into account. It is generally stated that fully turgid cells have a turgor pressure value which is equal to that of the cell and that flaccid cells have a value at or near zero. Other cellular mechanisms taken into consideration include the protoplast, solutes within the protoplast (solute potential), transpiration rates of the plant and the tension of cell walls. Measurement is limited depending on the method used, some of which are explored and explained below. Not all methods can be used for all organisms, due to size and other properties. For example, a diatom doesn't have the same properties as a plant, which would place constrictions on what could be used to infer turgor pressure.
Units.
Units used to measure turgor pressure are independent from the measures used to infer its values. Common units include bars, MPa, or newtons per square meter. 1 bar is equal to .1 MPa.
Methods.
Water potential equation.
Turgor pressure can be deduced when total water potential, Ψw, and osmotic potential, Ψs, are known in a water potential equation. These equations are used to measure the total water potential of a plant by using variables such as matric potential, osmotic potential, pressure potential, gravitational effects and turgor pressure. After taking the difference between Ψs and Ψw, the value for turgor pressure is given. When using this method, gravity and matric potential are considered to be negligible, since their values are generally either negative or close to zero.
Pressure-bomb technique.
The pressure bomb technique was developed by Scholander et al., reviewed by Tyree and Hammel in their 1972 publication, in order to test water movement through plants. The instrument is used to measure turgor pressure by placing a leaf (with stem attached) into a closed chamber where pressurized gas is added in increments. Measurements are taken when xylem sap appears out of the cut surface and at the point which it doesn't accumulate or retreat back into the cut surface.
Atomic force microscope.
Atomic force microscopes use a type of scanning probe microscopy (SPM). Small probes are introduced to the area of interest, and a spring within the probe measures values via displacement. This method can be used to measure turgor pressure of organisms. When using this method, supplemental information such as continuum mechanic equations, single force depth curves and cell geometries can be used to quantify turgor pressures within a given area (usually a cell).
Pressure probe.
This machine was originally used to measure individual algal cells, but can now be used on larger-celled specimens. It is usually used on higher plant tissues but wasn't used to measure turgor pressure until Hüsken and Zimmerman improved on the method. Pressure probes measure turgor pressure via displacement. A glass micro-capillary tube is inserted into the cell and whatever the cell exudes into the tube is observed through a microscope. An attached device then measures how much pressure is required to push the emission back into the cell.
Micro-manipulation probe.
These are used to accurately quantify measurements of smaller cells. In an experiment by Weber, Smith and colleagues, single tomato cells were compressed between a micro-manipulation probe and glass to allow the pressure probe's micro-capillary to find the cell's turgor pressure.
Theoretical speculations.
Negative turgor pressure.
It has been observed that the value of Ψw decreases as the cell becomes more dehydrated, but scientists have speculated whether this value will continue to decrease but never fall to zero, or if the value can be less than zero. There have been studies which show that negative cell pressures can exist in xerophytic plants, but a paper by M. T. Tyree explores whether this is possible, or a conclusion based on misinterpreted data. In his paper, he concludes that by miscategorizing "bound" and "free" water in a cell, researchers that claimed to have found negative turgor pressure values were incorrect. By analyzing the isotherms of apoplastic and symplastic water, he shows that negative turgor pressures cannot be present within arid plants due to net water loss of the specimen during droughts. Despite his analysis and interpretation of data, negative turgor pressure values are still used within the scientific community.
Tip growth in higher plants.
A hypothesis formed by M. Harold and his colleagues suggests that tip growth in higher plans is amoebic in nature, and isn't caused by turgor pressure as is widely believed, meaning that extension is caused by the actin cytoskeleton in these plant cells. Regulation of cell growth is implied to be caused by cytoplasmic micro-tubules which control the orientation of cellulose fibrils, which are deposited into the adjacent cell wall and results in growth. In plants, the cells are surrounded by cell walls and filamentous proteins which retain and adjust the plant cell's growth and shape. As explained in the paper, lower plants grow through apical growth, which differs since the cell wall only expands on one end of the cell. Further more studying on this topic is put on hold due to the pandemic.


Urocortin III

Urocortin III is a 38 amino acid peptide that is a member of the CRF family of peptides. Unlike Urocortin I, and similar to Urocortin II, Urocortin III is highly selective for the CRF2 receptor and does not show affinity for the CRF binding protein.
Urocortin II has been shown to have anorexigenic effects and hypotensive effects similar to Urocortin, but does not induce secretion of ACTH.


Evelyn Brower Man

Evelyn Brower Man (7 October 1904 – 3 September 1992) was an American biochemist. She was a leading woman in developing the first test to detect hormone levels in the thyroid gland.
Early life and education.
Evelyn B. Man was born in Lawrence, New York, but she grew up in North Stonington, Connecticut. Man's father, Edward Man, was an attorney from New York City and her mother was Mary Hewitt Man.
Man graduated from Wheeler High School, and then, in 1925, she graduated from Wellesley College with a degree in chemistry. Man graduated from Yale with a doctorate degree in physiological chemistry in 1932.
Career.
From 1928 to 1961, Man worked as a researcher, and technician, and then a professor at Yale. She worked at a lab at Yale with John P. Peters and Herman Yannet where they developed the first test to detect hormone levels in the thyroid gland. The test was called Butanol-Extractable Iodine (BEI) test. In 1961, Man continued her research at Brown University, where she discovered infants with low hormone levels in the thyroid gland later developed a cognitive disability as children. Man advocated for infants to get their thyroid hormone levels tested. Man also studied the effects of nuclear radiation on the thyroid gland in Japanese survivors.
In 1970, Man retired from Brown University. Throughout her career, Man published 156 scientific papers and published her last paper in 1991.
For her work, Man was awarded the American Thyroid Association's Distinguished Service Award in 1976 and the United Cerebral Palsy Award for Research.
Death.
On September 3, 1992, Man died of lung cancer in her home in West Hartford, Connecticut. Man was 87 years old at the time of her death.


Lowland streaked tenrec

The lowland streaked tenrec ("Hemicentetes semispinosus") is a small tenrec found in Madagascar.
Distribution and habitat.
The species is found in tropical lowland rain forest, in the northern and eastern parts of Madagascar.
It can be found on land, splashing in shallow waters or digging underground.
Description.
Physical appearance.
The lowland streaked tenrec ("Hemicentetes semispinosus") belongs to the family Tenrecidae in the order Afrosoricida, and more specifically to the subfamily of the spiny tenrecs Tenrecinae. The average body size for "H. semispinosus" is a length of however adults have been recorded to grow up to a maximum of . Body weight for adults of this species can range from . This species has a black spiny pelage with yellow or chestnut-brown stripes that run the length of the body. There is a median yellow stripe that runs down the rostrum along with one dorsal and two lateral stripes that mark the length of the body and may serve as a warning to predators. Quills are present in this species being longer and more numerous on the head and nuchal area. However, the ventral region contains few to no quills but have the ability to detach in predation defense.
Unique Aspects.
"H. semispinosus" possesses sensory hairs that are scattered on the dorsum that are similar to vibrissae. It has an evolutionary adaptation for its semifossorial habits with a well developed lateral and long heads of M. triceps brachii and enlarged M. teres major that function as an extensor of the elbow joint and as an adductor of the upper arm for digging. This species also has elongated hands and second, third, and fourth digit adaptation that acts as the main fossorial adaptation. The middle of the skull of this species is long and low, the alveolar processes of the maxilla, premaxilla and mandible are reduced and the palate narrow. The teeth are small, spaced, and placed farther forward on the skull. The temporal muscles, sagittal, and nuchal crests are weaker compared to other tenrec species.
Population Threats.
These tenrecs, "H. semispinosus", are threatened primarily by the loss of their natural habitat due to continuous deforestation, as it is with many other animals in the Madagascar region. This species is also being hunted for food.
Behavior.
Diet.
The lowland streaked tenrec is active both during the day and at night. Its diet is made up primarily of earthworms, but it will sometimes prey on other invertebrates as well. It may be seen stamping its feet on the ground with its fore-paws, an adaptation which is believed to increase earthworm activity for easier foraging. Most tenrecs possess a long snout for poking around in the ground to find their food. They are also capable of eating fruit. While the streaked tenrec does eat earthworms it seems to affect them. The way it affects them is by their teeth which there would be scratches and pits that are caused by dirt.
Reproduction.
Breeding takes place during October to December and possibly at other times, depending upon local food supply and temperature. The gestation period lasts 58 days, and the female gives birth to usually between 5 and 8 young. The young are weaned at 18 to 25 days.
Shelter.
The streaked tenrec lives in long, shallow burrows which are usually occupied by family groups.
Spines as tools.
"H. semispinosus" has hard keratinous quills located in the mid-dorsal region that act as a sounding device and are thought to be used for communication between mother and young and/or a warning signal to predators. Movement of these quills causes the tips to rub together and create a high frequency sound. These quills are located in a small area of the mid-dorsal region in a group of seven to sixteen arranged in three rows. Five quills run laterally on each side and is flanked by five to six quills being light brown in color. The arrangement and number of quills does not alter during growth and neither does the length. The circumference of the quills however, does change from juvenile to adult.
When an individual is aggravated a defense response is produced by erecting its quills laterally and forward which produces sound when the quills vibrate. "H. semispinosus" has a highly developed sense of smell and this response along with foot stamping is also produced when the odor of a predator is detected. This display additionally occurs when males fight for females and when unfamiliar males come across one another. Female encounters however, have tactile contact and then increase the distance between each other. It uses its quills to communicate in two different ways, by raising them in agitation or by rubbing them together in a method known as stridulation – best known as the type noise produced by crickets and cicadas. The sound produced is too high to be perceived by human ears.
Sound.
The streaked tenrec is the only mammal known to use stridulation for generating sound, a method more commonly associated with insects and snakes. Due to its rarity, there is not sufficient information regarding the functional-morphological mechanism of the streaked tenrec. The sounding quills are different from the spines and hair and are found in the mid-dorsal region of the streaked tenrec. The arrangement and length are similar throughout the streaked tenrec's life span, making up three rows in its midline area and adjacent areas bilaterally.
Cutaneous muscles underneath the quills were confirmed and are known as quill vibrator disc; they are around 16.8 mm long and 8.55 mm in width for an adult. These cutaneous muscles were the apparatus that contribute the vibration of the quills and production of sound for communication.
Physiology.
The streaked tenrec has the ability to enter torpor seasonally however, it is dependent on altitude, age, fat stores, and temperature. Torpor for this species generally occurs during June and July and during winter. However, "H. semispinosus" is a facultative hibernator and will come out of torpor during winter and forage. When foraging the soil and leaf litter is prodded with the tip of the nose until prey is detected. Elongated hands and digit adaptation (digits 2, 3, and 4) are the tenrecs main digging apparatus allowing it to unearth and pull its prey form the earth.
The skull has an elongated rostrum with a slender jaw with small spaced dentition placed more forward in the mouth. This species has zalambdodont molars with a dental formula of I 3/3, C 1/1, P 3/3, M 3/3 having a total of 40 teeth. The sagittal crest and nuchal are less prominent in this species and the zygomatic processes are long and slender resulting in less projection from the sides of the skull. The occipital region in this species along with the visceral skeleton are commonly very conservative.
It is also very closely related to the Highland Streaked Tenrec.


Charles Bouman

Charles Addison Bouman, Jr. is the Showalter Professor of Electrical and Computer Engineering and Biomedical Engineering at Purdue University, where he has taught since 1989. His research focuses on applications of image processing in various contexts, including medicine, materials science, and consumer imaging. His work led to the development of the first commercial CT scan technology to use model-based iterative reconstruction. He is a co-inventor on over fifty patents in the field of consumer imaging. He is a member of the National Academy of Inventors, as well as a fellow of the Institute of Electrical and Electronics Engineers, the American Institute for Medical and Biological Engineering, the Society for Imaging Science and Technology, and SPIE. He was formerly the editor-in-chief of "IEEE Transactions on Image Processing".
He is the father of computing scientist Katie Bouman.


MARCM

Mosaic analysis with a repressible cell marker, or MARCM, is a genetics technique for creating individually labeled homozygous cells in an otherwise heterozygous "Drosophila melanogaster". It has been a crucial tool in studying the development of the "Drosophila" nervous system. This technique relies on recombination during mitosis mediated by FLP-FRT recombination. As one copy of a gene, provided by the balancer chromosome, is often enough to rescue a mutant phenotype, MARCM clones can be used to study a mutant phenotype in an otherwise wildtype animal.
Crosses.
In order to label small populations of cells from a common progenitor, MARCM uses the GAL4-UAS system. A marker gene such as GFP is placed under control of a UAS promoter. GAL4 is ubiquitously expressed in these flies, thus driving marker expression. In addition, GAL80 is driven by a strong promoter such as tubP. Gal80 is an inhibitor of GAL4, and will suppress GFP expression under normal conditions. This tubP-GAL80 element is placed distal to an FRT site. A second FRT site is placed in trans to the GAL80 site, usually with a gene or mutation of interest distal to it. Finally, FLP recombinase is driven by an inducible promoter such as heat shock.
When FLP transcription is induced, it will recombine the chromosomes at the two FRT sites in cells undergoing mitosis. These cells will divide into two homozygous daughter cells—one carrying both GAL80 elements, and one carrying none. The daughter cell lacking GAL80 will be labeled due to expression of the marker via the GAL4-UAS system. All subsequent daughter cells from this progenitor will also express the marker.
Labs will often have MARCM-ready lines which have the inducible FLP, GAL80 distal to a FRT site, GAL4, and UAS-Marker. These can be readily crossed with flies that have a mutation of interest distal to a FRT site.
Uses.
By taking advantage of MARCM, one can easily trace all the cells that have been generated from a single progenitor. This is useful tool in tracking development and specific cell lineages in various environmental conditions. Applications for MARCM include studying neuronal circuits, clonal analysis, genetic screens, spermatogenesis, growth cone development, neurogenesis, and tumor metastasis.
Many advances in the understanding of Drosophila development have been achieved through MARCM. The development, lineages, and characterizations of secondary axon tracts, anatomical maps of cholinergic neurons in the visual systems, lineages giving rise to a thoracic hemineuromere scaffold and the developmental framework for CNS architecture, the role of Delta in developmental programming in the ventral nerve cord, the wake-promoting octopaminergic cells in the medial protocerebrum, genes involved in neuronal morphogenesis of the mushroom bodies, and the regulation of commissural axon guidance have all been identified through MARCM techniques.
Variations.
There are many variations of MARCM. Twin-spot MARCM allows for labeling of sister clones with two separate markers, thus allowing for a higher resolution of lineage tracing. In reverse MARCM, the mutation of interest is placed on the same chromosome as GAL80, so that the wild-type homozygous clones will be labeled. Flip-Out MARCM highlights individual cells inside of mutant clones (ref "Drosophila Dscam is required for divergent segregation of sister branches and suppresses ectopic bifurcation of axons," Neuron, 2002). The Q system allows for GAL4 independent MARCM by using the QF/QS system. Lethal MARCM allows for the generation of large marked homozygous populations by including a lethal mutation near the GAL80 site. Dual-expression control MARCM uses the LexA-VP16 transcriptional system in concordance with GAL4-UAS. MARCM is also often used as a genetic screen.


Liver stage antigens

Liver stage antigens (LSA) are a set of peptides from" Plasmodium falciparum" that are recognized by the body's immune system.
The two most studied ones are:


John Pomfret (poet)

John Pomfret (1667–1702) was an English poet and clergyman.
John Pomfret was the son of Thomas Pomfret, vicar of Luton, and was educated at Bedford School. His mother was Catherine Dobson, the only surviving daughter of English Civil War painter, William Dobson. After graduating from Queens' College, Cambridge Pomfret was appointed rector of Maulden in Bedfordshire in 1695.
He published a number of poems, and was regarded as significant enough in his time to be included by Samuel Johnson in his "Lives of the Poets." 'The Choice' is the poem for which Pomfret is now probably most remembered, especially as it was chosen by Roger Lonsdale as the first poem in "The New Oxford Book of Eighteenth Century Verse". It is a poem which celebrates an ideal life of genteel moderation in the country. Although Pomfret was married, 'The Choice' suggests the ideal life to be that of a bachelor, who can spend his days among the classics in his library and drinking (moderately) with two 'brave, gen'rous and witty' friends. However, he would also like there to be a 'witty nymph' living nearby whose 'conversation' would give his life a keen edge. Unfortunately for Pomfret this last sentiment led indirectly to his death at the young age of 35. He had travelled to London to seek preferment from Dr.Henry Compton, Bishop of London, but the bishop had been informed that in 'The Choice' Pomfret had advocated the keeping of a mistress. He therefore kept Pomfret waiting in London. It was here that Pomfret caught the smallpox which killed him. It was once believed by some critics that he was a follower of Albaudism but this appears to have been the result of a misinterpretation of his poetry.


Alice Vrielink

Alice Vrielink is a structural biologist who the Professor of Structural Biology in the School of Molecular Sciences at the University of Western Australia. She conducts research in protein biochemistry and crystallography with a special focus on understanding the structural determinants governing enzyme chemistry.
Education.
Vrielink earned a Bachelor of Science in Chemistry and Masters of Science in Physical Chemistry at the University of Calgary in Canada. She received a PhD in Physics and a Diploma in Crystallography in University of London and Imperial College of Science and Technology, respectively.
Career.
Vrielink was an Assistant and Associate Professor at McGill University in Canada from 1994 to 2001. From 2000 until 2007 she served as a Research Professor at the University of California, Santa Cruz and then joined the faculty at UWA as Professor of Structural Biology in 2007.
Vrielink mapped the molecular structure of EptA, a protein that shields superbugs from antibiotics. This work has been covered by the BBC, ABC, Times Higher Education, The West Australian, and Particle.
Vrielink was a member of the 2014 National Committee on Crystallography She has been a member of the Australian Society for Biochemistry and Molecular Biology, the British Crystallographic Association, the Asian Crystallographic Society, and the American Crystallographic Association. She is a past president of the Society of Crystallographers of Australia and New Zealand (SCANZ). She has authored and co-authored many articles on various topics in biochemistry and crystallography.


Callipeltin

Callipeltin A and B are bio-active isolates of marine invertebrates.


Glyoxylate cycle

The glyoxylate cycle, a variation of the tricarboxylic acid cycle, is an anabolic pathway occurring in plants, bacteria, protists, and fungi. The glyoxylate cycle centers on the conversion of acetyl-CoA to succinate for the synthesis of carbohydrates. In microorganisms, the glyoxylate cycle allows cells to utilize two carbons (C2 compounds), such as acetate, to satisfy cellular carbon requirements when simple sugars such as glucose or fructose are not available. The cycle is generally assumed to be absent in animals, with the exception of nematodes at the early stages of embryogenesis. In recent years, however, the detection of malate synthase (MS) and isocitrate lyase (ICL), key enzymes involved in the glyoxylate cycle, in some animal tissue has raised questions regarding the evolutionary relationship of enzymes in bacteria and animals and suggests that animals encode alternative enzymes of the cycle that differ in function from known MS and ICL in non-metazoan species.<ref name="doi=10.1007/s10893-006-0004-3"></ref>
Plants as well as some algae and bacteria can use acetate as the carbon source for the production of carbon compounds. Plants and bacteria employ a modification of the TCA cycle called the glyoxylate cycle to produce four carbon dicarboxylic acid from two carbon acetate units. The glyoxylate cycle bypasses the two oxidative decarboxylation reactions of the TCA cycle and directly converts isocitrate through isocitrate lyase and malate synthase into malate and succinate.
Similarities with TCA cycle.
The glyoxylate cycle utilizes five of the eight enzymes associated with the tricarboxylic acid cycle: citrate synthase, aconitase, succinate dehydrogenase, fumarase, and malate dehydrogenase. The two cycles differ in that in the glyoxylate cycle, isocitrate is converted into glyoxylate and succinate by isocitrate lyase (ICL) instead of into α-ketoglutarate. This bypasses the decarboxylation steps that take place in the citric acid cycle (TCA cycle), allowing simple carbon compounds to be used in the later synthesis of macromolecules, including glucose. Glyoxylate is subsequently combined with acetyl-CoA to produce malate, catalyzed by malate synthase. Malate is also formed in parallel from succinate by the action of succinate dehydrogenase and fumarase.
Role in gluconeogenesis.
Fatty acids from lipids are commonly used as an energy source by vertebrates as fatty acids are degraded through beta oxidation into acetate molecules. This acetate, bound to the active thiol group of coenzyme A, enters the "citric acid cycle" (TCA cycle) where it is fully oxidized to carbon dioxide. This pathway thus allows cells to obtain energy from fat. To utilize acetate from fat for biosynthesis of carbohydrates, the glyoxylate cycle, whose initial reactions are identical to the TCA cycle, is used.
Cell-wall containing organisms, such as plants, fungi, and bacteria, require very large amounts of carbohydrates during growth for the biosynthesis of complex structural polysaccharides, such as cellulose, glucans, and chitin. In these organisms, in the absence of available carbohydrates (for example, in certain microbial environments or during seed germination in plants), the glyoxylate cycle permits the synthesis of glucose from lipids via acetate generated in fatty acid β-oxidation.
The glyoxylate cycle bypasses the steps in the citric acid cycle where carbon is lost in the form of CO2. The two initial steps of the glyoxylate cycle are identical to those in the citric acid cycle: "acetate → citrate → isocitrate". In the next step, catalyzed by the first glyoxylate cycle enzyme, isocitrate lyase, isocitrate undergoes cleavage into succinate and glyoxylate (the latter gives the cycle its name). Glyoxylate condenses with acetyl-CoA (a step catalyzed by malate synthase), yielding malate. Both malate and oxaloacetate can be converted into phosphoenolpyruvate, which is the product of phosphoenolpyruvate carboxykinase, the first enzyme in gluconeogenesis. The net result of the glyoxylate cycle is therefore the production of glucose from fatty acids. Succinate generated in the first step can enter into the citric acid cycle to eventually form oxaloacetate.
Function in organisms.
Plants.
In plants the glyoxylate cycle occurs in special peroxisomes which are called glyoxysomes. This cycle allows seeds to use lipids as a source of energy to form the shoot during germination. The seed cannot produce biomass using photosynthesis because of lack of an organ to perform this function. The lipid stores of germinating seeds are used for the formation of the carbohydrates that fuel the growth and development of the organism.
The glyoxylate cycle can also provide plants with another aspect of metabolic diversity. This cycle allows plants to take in acetate both as a carbon source and as a source of energy. Acetate is converted to acetyl CoA (similar to the TCA cycle). This acetyl CoA can proceed through the glyoxylate cycle, and some succinate is released during the cycle. The four carbon succinate molecule can be transformed into a variety of carbohydrates through combinations of other metabolic processes; the plant can synthesize molecules using acetate as a source for carbon. The acetyl CoA can also react with glyoxylate to produce some NADPH from NADP+, which is used to drive energy synthesis in the form of ATP later in the electron transport chain.
Pathogenic fungi.
The glyoxylate cycle may serve an entirely different purpose in some species of pathogenic fungi. The levels of the main enzymes of the glyoxylate cycle, ICL and MS, are greatly increased upon contact with a human host. Mutants of a particular species of fungi that lacked ICL were also significantly less virulent in studies with mice compared to the wild type. The exact link between these two observations is still being explored, but it can be concluded that the glyoxylate cycle is a significant factor in the pathogenesis of these microbes.
Vertebrates.
Vertebrates were once thought to be unable to perform this cycle because there was no evidence of its two key enzymes, isocitrate lyase and malate synthase. However, some research suggests that this pathway may exist in some, if not all, vertebrates.
 Specifically, some studies show evidence of components of the glyoxylate cycle existing in significant amounts in the liver tissue of chickens. Data such as these support the idea that the cycle could theoretically occur in even the most complex vertebrates. Other experiments have also provided evidence that the cycle is present among certain insect and marine invertebrate species, as well as strong evidence of the cycle's presence in nematode species. However, other experiments refute this claim. Some publications conflict on the presence of the cycle in mammals: for example, one paper has stated that the glyoxylate cycle is active in hibernating bears, but this report was disputed in a later paper. Evidence exists for malate synthase activity in humans due to a dual functional malate/B-methylmalate synthase of mitochondrial origin called CLYBL expressed in brown fat and kidney. Vitamin D may regulate this pathway in vertebrates.
Inhibition of the glyoxylate cycle.
Due to the central role of the glyoxylate cycle in the metabolism of pathogenic species including fungi and bacteria, enzymes of the glyoxylate cycle are current inhibition targets for the treatment of diseases. Most reported inhibitors of the glyoxylate cycle target the first enzyme of the cycle (ICL). Inhibitors were reported for "Candida albicans" for potential use as antifungal agents. The mycobacterial glyoxylate cycle is also being targeted for potential treatments of tuberculosis.
Engineering concepts.
The prospect of engineering various metabolic pathways into mammals which do not possess them is a topic of great interest for bio-engineers today. The glyoxylate cycle is one of the pathways which engineers have attempted to manipulate into mammalian cells. This is primarily of interest for engineers in order to increase the production of wool in sheep, which is limited by the access to stores of glucose. By introducing the pathway into sheep, the large stores of acetate in cells could be used in order to synthesize glucose through the cycle, allowing for increased production of wool. Mammals are incapable of executing the pathway due to the lack of two enzymes, isocitrate lyase and malate synthase, which are needed in order for the cycle to take place. It is believed by some that the genes to produce these enzymes, however, are pseudogenic in mammals, meaning that the gene is not necessarily absent, rather, it is merely "turned off".
In order to engineer the pathway into cells, the genes responsible for coding for the enzymes had to be isolated and sequenced, which was done using the bacteria "E.coli", from which the AceA gene, responsible for encoding for isocitrate lyase, and the AceB gene, responsible for encoding for malate synthase were sequenced. Engineers have been able to successfully incorporate the AceA and AceB genes into mammalian cells in culture, and the cells were successful in translating and transcribing the genes into the appropriate enzymes, proving that the genes could successfully be incorporated into the cell’s DNA without damaging the functionality or health of the cell. However, being able to engineer the pathway into transgenic mice has proven to be difficult for engineers. While the DNA has been expressed in some tissues, including the liver and small intestine in test animals, the level of expression is not high, and not found to be statistically significant. In order to successfully engineer the pathway, engineers would have to fuse the gene with promoters which could be regulated in order to increase the level of expression, and have the expression in the right cells, such as epithelial cells.
Efforts to engineer the pathway into more complex animals, such as sheep, have not been effective. This illustrates that much more research needs to be done on the topic, and suggests it is possible that a high expression of the cycle in animals would not be tolerated by the chemistry of the cell. Incorporating the cycle into mammals will benefit from advances in nuclear transfer technology, which will enable engineers to examine and access the pathway for functional integration within the genome before its transfer to animals.
There are possible benefits, however, to the cycle's absence in mammalian cells. The cycle is present in microorganisms that cause disease but is absent in mammals, for example humans. There is a strong plausibility of the development of antibiotics that would attack the glyoxylate cycle, which would kill the disease-causing microorganisms that depend on the cycle for their survival, yet would not harm humans where the cycle, and thus the enzymes that the antibiotic would target, are absent.


Christian Karsten Hansen

Christian Karsten Hansen (born 18 August 1966) is a Danish biotechnology entrepreneur, investor and inventor, with work in new drugs, molecular biology and biochemistry.
Personal background.
Originally from Copenhagen (Denmark), he spent his childhood in Antwerp, Belgium and Caracas, Venezuela before completing high school at Sorø Academy in 1984. Following graduation as M.Sc. chemical engineering from the Technical University of Denmark in 1989, PhD work in molecular biology and biochemistry was conducted at the Pasteur Institute, France and the University of Salamanca, Spain. He also completed an MBA from the Edinburgh Business School, Scotland.
Professional background.
Hansen held positions as senior scientist and director of intellectual property management at Novo Nordisk 1992–1999, and was a member of Enzyme Research Management. He co-founded one of the early Danish biotechnology companies, Profound Pharma, in 1999, with Jan Møller Mikkelsen, and remained co-CEO thereof until its acquisition by Maxygen in 2000.
In 2001, he co-founded the investment firm Nordic Biotech Advisors, subsequently renamed NB Capital. Also in 2001, he founded C Hansen Invest.
Since 2001, Hansen has co-founded and/or been a board member of numerous privately held and listed biotechnology companies including Osteologix, Nuevolution, Curalogic, Forward Pharma, Rose Pharma, Poalis, Aditech Pharma, Veloxis Pharmaceuticals, H Pharmaceuticals, Isar Pharma, and ParaTech.
Patents.
Hansen has filed numerous patent applications in the fields of genetics of bacteria, cellulases and other enzymes, osteoporosis, and protein engineering and uses of biopharmaceuticals. He is named as inventor of issued European patents 510091, 1250154, 1425304, 1534305, 1622629, 1622630, 1732575, 1745791 2266584 and 2266585, and US patents 5,843,720, 5,916,796, 6,066,473, 6,555,660, 6,646,110, 6,831,158, 7,230,081, 7,232,562, 7,504,237, 7,550,565, 7,550,566, 7,595,342, 7,696,153 and 8,541,471.
Various compounds from these companies and patents are in mid and late stages of clinical development.


Srinivas Sridhar

Srinivas Sridhar is an American scientist, educator and academic. He is known for his research and educational activities in the area of nanomedicine, MRI, quantum chaos, superconductivity and neurotechnology. Srinivas Sridhar currently holds the position of University Distinguished Professor at Northeastern University in the Departments of Physics, Biomedical Engineering and Chemical Engineering. In 2016, Sridhar received the Biomedical Engineering Society Diversity Award. He was elected Fellow of the American Physical Society in 2008.
Education.
Sridhar received his PhD in physics from California Institute of Technology in 1983 under the mentorship of Professor James E. Mercereau. He was an Associate Research Scientist at UCLA from 1984-1986.
Academic career and research.
Since 1984, Sridhar's scientific and academic career has been closely associated with Northeastern University. Since 2011, Sridhar has been a visiting Lecturer at Harvard Medical School where he researches radiation oncology. He is the founding director of the Nanomedicine Innovation Center, an interdisciplinary center with research and education thrusts in nanomedicine. Sridhar is the author of over 450 publications, on his work in nanomedicine, neurotechnology, MRI, nanophotonics, nanomaterials, metamaterials, quantum chaos, superconductivity and collective excitations in materials. His paper in Nature in 2003 was listed among Breakthroughs of 2003 by the journal Science.
Sridhar has also developed innovative educational programs. Sridhar is Director and Principal Investigator of the CaNCURE cancer nano-medicine program supported by the National Institute of Health and Director of the Nanomedicine Academy and IGERT Doctoral graduate programs supported by the National Science Foundation. A distinguished academic, he served as Vice Provost for Research at Northeastern University from 2004 to 2008, overseeing the University’s research portfolio.


Chloroflexus aurantiacus

Chloroflexus aurantiacus is a photosynthetic bacterium isolated from hot springs, belonging to the green non-sulfur bacteria. This organism is thermophilic and can grow at temperatures from 35 °C to 70 °C (94.998 to 158 °F). "Chloroflexus aurantiacus" can survive in the dark if oxygen is available. When grown in the dark, "Chloroflexus aurantiacus" has a dark orange color. When grown in sunlight it is dark green. The individual bacteria tend to form filamentous colonies enclosed in sheaths, which are known as trichomes.
Physiology.
As a genus, "Chloroflexus" spp. are filamentous anoxygenic phototrophic (FAP) organisms that utilize type II photosynthetic reaction centers containing bacteriochlorophyll "a" similar to the purple bacteria, and light-harvesting chlorosomes containing bacteriochlorophyll "c" similar to green sulfur bacteria of the "Chlorobi". Like other members of its phylum ("cf." Chloroflexi), the species stains Gram negative, yet has a single lipid layer (monoderm), but with thin peptidoglycan, which is compensated for by S-layer protein.
As the name implies, these anoxygenic phototrophs do not produce oxygen as a byproduct of photosynthesis, in contrast to oxygenic phototrophs such as cyanobacteria, algae, and higher plants. While oxygenic phototrophs use water as an electron donor for phototrophy, "Chloroflexus" uses reduced sulfur compounds such as hydrogen sulfide, thiosulfate, or elemental sulfur. This belies their obsolescent name green non-sulfur bacteria; however, "Chloroflexus" spp. can also utilize hydrogen(H2) as a source of electrons.
"Chloroflexus aurantiacus" is thought to grow photoheterotrophically in nature, but it has the capability of fixing inorganic carbon through photoautotrophic growth. Instead of using the Calvin-Benson-Bassham Cycle typical of plants, "Chloroflexus aurantiacus" has been demonstrated to use an autotrophic pathway known as the 3-Hydroxypropionate pathway.
The complete electron transport chain for "Chloroflexus" spp. is not yet known. Particularly, "Chloroflexus aurantiacus" has not been demonstrated to have a cytochrome "bc1" complex, and may use different proteins to reduce cytochrome "c"
Evolution of photosynthesis.
One of the main reasons for interest in "Chloroflexus aurantiacus" is in the study of the evolution of photosynthesis. As terrestrial mammals, we are most familiar with photosynthetic plants such as trees. However, photosynthetic eukaryotes are a relatively recent evolutionary development. Photosynthesis by eukaryotic organisms can be traced back to endosymbiotic events in which non-photosynthetic eukaryotes internalized photosynthetic organisms. The chloroplasts of trees still retain their own DNA as a molecular remnant that indicated their origin as photosynthetic bacteria.
The "respiration early" hypothesis.
How did photosynthesis arise in bacteria? The answer to this question is complicated by the fact that there are several types of light-harvesting energy capture systems. "Chloroflexus aurantiacus" has been of interest in the search for origins of the so-called type II photosynthetic reaction center. One idea is that bacteria with respiratory electron transport evolved photosynthesis by coupling a light-harvesting energy capture system to the pre-existing respiratory electron transport chain. Thus, rare organisms like "Chloroflexus aurantiacus" that can survive using either respiration or photosynthesis are of interest in on-going attempts to trace the evolution of photosynthesis.


Azumolene

Azumolene is an experimental drug which is a derivative of dantrolene. In animal studies, azumolene showed similar efficacy to dantrolene at controlling symptoms of malignant hyperthermia but with better water solubility and lower toxicity, albeit with lower potency.


Armillaria calvescens

Armillaria calvescens is a species of mushroom in the family Physalacriaceae. Similar in appearance to "Armillaria gallica", this species is often found on maple in Canada and New England, as well as other hardwoods in the western United States. The mycelium of the fungus is bioluminescent.


Ammonium sulfate precipitation

Ammonium sulfate precipitation is one of the most commonly used methods for large and laboratory scale protein purification and fractionation that can be used to separate proteins by altering their solubility in the presence of a high salt concentration.
Properties.
Ammonium sulfate is an inorganic salt with a high solubility that disassociates into ammonium (NH4+) and sulfate (SO42−) in aqueous solutions. Ammonium sulfate is especially useful as a precipitant because it is highly soluble, stabilizes protein structure, has a relatively low density, is readily available, and is relatively inexpensive.
Mechanism.
Ammonium sulfate, as well as other neutral salts, will stabilize proteins by preferential solvation. Proteins are usually stored in ammonium sulfate because it inhibits bacterial growth. With the addition of ammonium sulfate, proteins unfolded by denaturants can be pushed into their native conformations. This can be seen with the folding of recombinant proteins.
The solubility of proteins varies according to the ionic strength of the solution, thus according to the salt concentration. At low ion concentrations (<0.5 M), the solubility of proteins increases with increasing salt concentration, an effect termed "salting in". As the salt concentration is further increased, the solubility of the protein begins to decrease. At a sufficiently high ionic strength, the protein will precipitate out of the solution, an effect termed "salting out". When the ammonium (NH4+) and sulfate (SO42−) ions are within the aqueous solution they are attracted to the opposite charges evident on the compound that is being purified. This attraction of opposite charges prevents the water molecules from interacting with the compound being purified, leading to the precipitation or "salting out".
Proteins differ markedly in their solubilities at high ionic strength, therefore, "salting out" is a very useful procedure to assist in the purification of the desired protein. Ammonium sulfate is commonly used for precipitation because of its high solubility, additionally, it forms two ions high in the Hofmeister series. Because these two ions are at the end of Hofmeister series, ammonium sulfate can also stabilize a protein structure. The ammonium sulfate solubility behavior for a protein is usually expressed as a function of the percentage of saturation. A solubility curve can be determined by plotting the log of the experimentally determined solubility, expressed as mg/mL, versus the percentage saturation of ammonium sulfate.
With the mechanism of salting-out, there is an omission of the salt from the layer of water, which is closely associated with the surface of the protein, known as the hydration layer. The hydration layer plays a vital role in sustaining solubility and suitable natural conformation. There are three main protein-water interaction: ion hydration between charged side chains, hydrogen bonding between polar groups and water, and hydrophobic hydration. Once salt is added to the mixture, there is an increase in the surface tension of the water, thus increasing hydrophobic interactions between water and the protein of interest. The protein of interest then reduces its surface area, which diminishes its contact with the solvent. This is shown by the folding and self-association, which ultimately leads to precipitation. The folding and self-association of the protein pushes out free water, leading to an increase in entropy and making this process energetically favorable.
Procedure.
Typically, the ammonium sulfate concentration is increased stepwise, and the precipitated protein is recovered at each stage. This is usually done by adding solid ammonium sulfate; however, calculating the amount of ammonium sulfate that should be added to add to a solution to achieve the desired concentration may be difficult because the addition of ammonium sulfate significantly increases the volume of the solution. The amount of ammonium sulfate that should be added to the solution can be determined from published nomograms or by using an online calculator. The direct addition of solid ammonium sulfate does change the pH of the solution, which can lead to loss of enzyme activity. In those cases, the addition of saturated ammonium sulfate in a suitable buffer is used as an alternative to adding solid ammonium sulfate. In either approach, the resulting protein precipitate can be dissolved individually in a standard buffer and assayed to determine the total protein content.
The ammonium sulfate concentration added should be increased to a value that will precipitate most of the protein of interest whilst leaving the maximum amount of protein contaminants still in the solution. The precipitated protein of interest can subsequently be recovered by centrifugation and dissolved in standard buffer to prepare the sample for the next stage of purification.
In the next stage of purification, all this added salt needs to be removed from the protein. One way to do so is using dialysis, but dialysis further dilutes the concentrated protein. The better way of removing ammonium sulfate from the protein is mixing the precipitate protein in a buffer containing a mixture of SDS, Tris-HCl, and phenol and centrifuging the mixture. The precipitate that comes out of this centrifugation will contain salt-less concentrated protein.
Applications.
Ammonium sulfate precipitation is a useful technique as an initial step in protein purification because it enables quick, bulk precipitation of cellular proteins. It is also often employed during the later stages of purification to concentrate protein from dilute solution following procedures such as gel filtration. The drawback of this method is that oftentimes different substances can precipitate along with the protein, and other purification techniques must be performed, such as ion chromatography or size-exclusion chromatography.


Barbara Shinn-Cunningham

Barbara Shinn-Cunningham (born 1964) is an American bioengineer and neuroscientist. She is director of the Carnegie Mellon University Neuroscience Institute, the George A. and Helen Dunham Cowan Professor of Auditory Neuroscience, and Professor of Psychology, Electrical and Computer Engineering, and Biomedical Engineering.
Career.
Prior to moving to Carnegie Mellon, where she runs the Laboratory in Multisensory Neuroscience, Shinn-Cunningham was a Professor of Biomedical Engineering at Boston University (BU). She attended Brown University as an undergraduate, where she earned an Sc.B. in Electrical Engineering. She earned both her master's degree and Ph.D. from the Massachusetts Institute of Technology in Electrical and Computer Engineering. She worked at Bell Communications Research, MIT Lincoln Laboratory, and Sensimetrics before joining the faculty at BU. She is an auditory neuroscientist best known for her work on attention and the cocktail party problem, sound localization, and the effects of room acoustics and reverberation on hearing.
Shinn-Cunningham's lab uses a range of techniques to understand neural coding and perception, including psychoacoustics, cortical electroencephalography and magnetoencephalography, brainstem frequency following responses, and computational modeling. She also collaborates with researchers conducting functional magnetic resonance imaging and neurophysiology. She is particularly interested in "hidden hearing loss", the trouble people with otherwise normal hearing have in decoding overlapping conversations.
She has held numerous leadership positions in professional organizations, including as Vice President of the Acoustical Society of America, Treasurer and Member of Council of the Association for Research in Otolaryngology, and Chair of the AUD NIH study section. She regularly serves on advisory and review panels in academia and beyond. She is a Senior Editor for "eLife", and has served on the editorial boards of the "Journal of the Association for Research in Otolaryngology", the "Journal of Neurophysiology", and "Auditory Perception and Cognition".
Awards.
She is a fellow of the American Institute for Medical and Biological Engineering and the Acoustical Society of America (ASA). She has received fellowships from the Whitaker Foundation, the Alfred P Sloan Foundation and the National Security Science and Engineering Faculty Fellows program (now known as the Vannevar Bush Faculty Fellowship Program). She was the recipient of the biennial Mentorship Award from the Acoustical Society of America in 2013.
She was the eighth woman to receive any ASA Silver Medal and the first to receive the Helmholtz-Rayleigh Interdisciplinary Silver Medal (2019), which she was awarded in Psychological and Physiological Acoustics, Speech Communication, and Architectural Acoustics "for contributions to understanding the perceptual, cognitive, and neural bases of speech perception in complex acoustic environments."
In 2020, she was recognized by the Society for Neuroscience as a recipient of the Bernice Grafstein Award for Outstanding Accomplishments in Mentoring.
She is a Lifetime National Associate of the National Research Council of the National Academy of Science.
Personal.
Shinn-Cunningham is married to Dr. Robert K. Cunningham, an engineer-scientist who has worked in machine learning, computational vision, and cybersecurity. They have two sons, born in 1994 and 1996. She is an amateur oboist and English horn player. She took up saber fencing as an adult, and participated in the 2019 World Veteran Fencing Championships in Cairo, Egypt, where she was a member of the silver-medal-winning US Veteran Women's Saber Team, and placed seventh in the individual Women Vet50 category.


ClickSeq

ClickSeq is a click-chemistry based method for generating next generation sequencing libraries for deep-sequencing platforms including Illumina, HiSeq, MiSeq and NextSeq. Its function is similar to most other techniques for generating RNAseq or DNAseq libraries in that it aims to generate random fragments of biological samples of RNA or DNA and append specific sequencing adaptors to either end of every fragment, as per the requirements of the particular sequencing platform to be used (e.g. HiSeq).
In ClickSeq, reverse transcription (RT) reactions are supplemented with small amounts of 3’-azido-nucleotides (AzNTPs) at defined ratios to deoxyribonucleotides (dNTPs). AzNTPs are chain-terminators and therefore induce the stochastic termination of cDNA synthesis at an average length determined by the ratio of AzNTPs to dNTPs. This results in the production of single-stranded cDNA fragments that contain an azido-group at their 3' ends. These 3'-azido-blocked cDNA molecules are purified away from the components of the RT reaction, and subsequently 'click-ligated' to 5’ alkyne-modified DNA adaptors via copper-catalysed azide-alkyne cycloaddition (CuAAC). This generates ssDNA molecules with unnatural triazole-linked DNA backbones. Nevertheless, these templates are used in PCR reactions and amplified to generate a cDNA sequencing library with the appropriate 5' and 3' sequencing adapters and indices required for Next-Generation Sequencing. ClickSeq has predominantly been used to sequence viral RNA genomes such as Flock House virus, cricket paralysis virus, and Zika virus, due to its resilience to artifactual chimera formation.
Poly(A)-ClickSeq.
Poly(A)-ClickSeq is a variant of ClickSeq designed to target the junction of the three prime untranslated region (UTRs) and poly(A)-tails of the messenger RNAs (mRNAs) of higher-order organisms and of RNA viruses infecting these cells types. The core principle is similar to ClickSeq, however, the reverse-transcription step uses an oligo-dT primer (unanchored) to initiate cDNA synthesis from within the poly(A) tail and only three 3'azido-nucleotides (AzATP, AzGTP and AzCTP, collectively referred to as AzVTPs) are supplemented. Due to the omission of AzTTP, stochastic termination of cDNA synthesis cannot occur during reverse transcription of the poly(A)-tail. Rather, termination can only occur in the 3'UTR at a distance upstream of the poly(A) tail defined by the ratio of AzVTPs to dNTPs.
Applications.
ClickSeq and Poly(A)-ClickSeq provide specific applications over other common RNA-seq techniques. These include:


Androgen backdoor pathway

The androgen backdoor pathway is a collective name for all metabolic pathways where clinically relevant androgens are synthesized with roundabout of testosterone as an intermediate product. Initially described as pathway where 5α-reduction of 17α-hydroxyprogesterone ultimately leads to 5α-dihydrotestosterone, several other pathways have been since then discovered that lead to 11-oxyandrogens which are potent agonists of the androgen receptors. A backdoor pathway is an alternative to the conventional, canonical androgenic pathway that involves testosterone.
Dihydrotestosterone.
The primary feature of the androgen backdoor pathway is that 17α-hydroxyprogesterone (17-OHP) can be 5α-reduced and finally converted to 5α-dihydrotestosterone (DHT) via an alternative route that bypasses the conventional intermediates androstenedione and testosterone.
In mammals, this route is activated during normal prenatal development and leads to early male sexual differentiation. It was first described in the marsupials and later confirmed in humans.
In 21-hydroxylase deficiency or cytochrome P450 oxidoreductase deficiency, this route may be activated regardless of age and sex by even a mild increase in circulating 17-OHP levels.
The first step of this route is 5α-reduction of 17-OHP by SRD5A1/SRD5A2 enzymes to 5α-pregnan-17α-ol-3,20-dione. The next two intermediate products are 5α-pregnane-3α,17α-diol-20-one and androsterone. The final step is conversion of 5α-androstane-3α,17β-diol (androstanediol) to DHT by several 3α-oxidoreductases (HSD17B6, RDH16, etc). Hence, androstanediol is a marker of the backdoor pathway of DHT synthesis.
Therefore, the pathway can be outlined as 17-OHP → 5α-pregnan-17α-ol-3,20-dione → 5α-pregnane-3α,17α-diol-20-one → androsterone → androstanediol → DHT.
11-Oxyandrogens.
Another feature of the backdoor pathway is production of 11-oxygenated (oxygen atom on C11 position forms a ketone group) 19-carbon steroids, also termed 11-oxyandrogens: 11-ketotestosterone and 11-ketodihydrotestosterone, which are 11-keto forms of testosterone and DHT, respectively. The synthesis of 11-oxyandrogens in this pathway does not require testosterone or DHT as intermediate products. 11-oxyandrogens are potent and clinically relevant agonists of the androgen receptors. Potency of 11-ketotestosterone is similar to that of testosterone. 11-ketotestosterone may serve as the main androgen for healthy women.
11-oxyandrogens may be produced in physiologic quantities in healthy organisms, and in excessive quantities in the pathological conditions like 21-hydroxylase deficiency, polycystic ovary syndrome, benign prostatic hyperplasia in prostate cancer and disorders of sex development in neonates and in children.
In 21-hydroxylase deficiency, the steroid 11β-hydroxylase (11βOH) enzyme, also known is CYP11B1, stays at the initial step of 11-oxyandrogen production.
There are several routes that may lead to production of 11-oxyandrogens:
Clinical significance.
Unlike testosterone and androstenedione, androgens produced by the backdoor pathway, i.e. DHT and 11-oxyandrogens, cannot be converted by aromatase into estrogens.
The backdoor pathway is not always considered in the clinical evaluation of patients with hyperandrogenism. Ignoring this pathway may lead to diagnostic pitfalls and confusion, for example, in late onset congenital adrenal hyperplasia, where testosterone levels may be normal amid the symptoms of hyperandrogenism like hirsutism and acne.
History.
In April 1987, Benjamin Eckstein and colleagues reported that androstanediol, a direct precursor to DHT, is synthesized in immature rat testes in a pathway that predominantly involves 17-OHP but not androstenedione as an intermediate.
In October 2000, Geoffrey Shaw and colleagues demonstrated that prostate formation in a marsupial (tammar wallaby pouch young) was mediated by the testicular androgen androstanediol, which is higher in male than in female plasma during early sexual differentiation, identifying it as a key hormone in male development. They have shown that androstanediol acts in target tissues via DHT, i.e. is converted to DHT in target tissues, so that testosterone is not the only source of DHT.
In February 2003, Jean Wilson and colleagues described that DHT, a 5α-reduced androgen, can be synthesized from 17-OHP by two pathways: with and without testosterone as an intermediate. They have demonstrated that androstanediol, a precursor to DHT, is formed in the testes of tammar wallaby pouch young with 5α-pregnane-3α,17α-diol-20-one and androsterone as intermediates.
In July 2004, Mala Mahendroo and colleagues described that androstanediol is the predominant androgen in immature mouse testes, and that it is formed by two pathways; the main one involves testosterone, and a second utilizes the pathway progesterone → 5α-dihydroprogesterone → 5α-pregnane-3α-ol-20-one (allopregnanolone) → 5α-pregnane-3α,17α-diol-20-one → androsterone → androstanediol.
In November 2004, Richard Auchus coined the term "backdoor pathway" in a review called "The backdoor pathway to dihydrotestosterone". He defined the backdoor pathway as a "route to DHT that does not involve the testosterone intermediate". He emphasized that this alternative pathway seems to explain how potent androgens are produced under certain normal and pathological conditions when the conventional androgen biosynthetic pathway cannot fully explain the observed consequences.


5-MeO-DPT

5-MeO-DPT (also known as 5-methoxy-N,N-Dipropyltryptamine), is a psychedelic and entheogenic drug.
Chemistry.
The full chemical name is N-[2-(5-methoxy-1H-indol-3-yl)ethyl]-N-propylpropan-1-amine. It is classified as a tryptamine derivative.
Effects.
Little is known about the subjective effects of 5-MeO-DPT, but the nature of the compound is probably comparable to 5-MeO-DiPT, 5-MeO-DMT, or DPT, which are also psychedelic tryptamines/indoles. However, the duration of the above-mentioned drugs vary considerably.
Dosage.
5-MeO-DPT is ly active, with 3-10 mg representing a fully effective dosage for most users. Effects begin within three hours, and usually last 4 hours.


Naphthylaminopropane

Naphthylaminopropane (PAL-287) is an experimental drug under investigation as of 2007 for the treatment of alcohol and stimulant addiction.
Naphthylisopropylamine acts as a non-neurotoxic releasing agent of serotonin, norepinephrine, and dopamine, with EC50 values of 3.4 nM, 11.1 nM, and 12.6 nM, respectively. It also has affinity for the 5-HT2A, 5-HT2B, and 5-HT2C receptors (EC50 values = 466 nM, 40 nM, and 2.3 nM, respectively), and acts as a full agonist at 5-HT2B and as a partial agonist at 5-HT2C, while its affinity for 5-HT2A is probably too low to be significant.
In animal studies, naphthylisopropylamine was shown to reduce cocaine self-administration, yet produced relatively weak stimulant effects when administered alone, being a (much) lesser stimulant than d-amphetamine for comparison. Further research is now being conducted in primates to see if it will be a useful substitute for treating drug addiction in humans as well.
An important observation is that in behavioral studies, rodents would consistently self-administer selective norepinephrine and dopamine releasing agents such as d-amphetamine, yet compounds that also release serotonin like naphthylisopropylamine would not be self-administered. In addition to the drugs (acute) effects on self-administration, all of the available evidence suggests that the locomotor activation caused by the majority of dopamine releasers is also dampened when the drugs also cause serotonergic release. In fact, PAL-287 causes no locomotor activation at all (although admittedly the tests were only after acute dosing).
The high affinity of PAL-287 for 5-HT2C receptors meant that it functioned as a reliable anorectant and was being considered for this indication (i.e. weight loss). However, there were ultimately some concerns raised over the compounds affinity for 5HT2B receptors, since some of the more serious side effects of the serotonin releasing weight loss drug fenfluramine were linked to an activation of this receptor. Apparently, more research will have to be done to assess if PAL-287 causes activation of the 5HT2A and 5HT2B receptors in vivo. However, according to the authors, even the relatively safe drug MDMA causes heart disease, and the incidence being reported for fenfluramine was not that great, even though the evidence being presented was indisputable. Thus it is relatively more likely that any of the more serious side effects from using PAL-287 will only occur in cases of overdose, and not when using a clinically responsible amount of the drug.


Little Nicky (cat)

Little Nicky (born October 17, 2004) is the first commercially produced cat clone. He was produced from the DNA of a 17-year-old Maine Coon cat named Nicky who died in 2003. Little Nicky's owner, a north Texas woman named Julie (whose last name was not released) paid $50,000 to have Nicky cloned. Little Nicky's owner reported that the cat shared many characteristics with his predecessor, including a similar personality and appearance.
Origin and Cloning.
The cloning of Little Nicky was performed by the California-based company Genetic Savings & Clone, which later closed in 2006. This followed the first successful cloning of a cat (CC) by the company in conjunction with Texas A&M University. The cloning was performed by the chromatin transfer technique, a variant of nuclear transfer. The cloning of Little Nicky was a result of an offer by the company called the "Nine Lives Extravaganza" launched in 2004.
Ethical Controversy.
Groups such as the Humane Society of the United States, the Best Friends Animal Society, and other groups for animal welfare spoke out against the creation of pet clones such as Little Nicky. They emphasized that the $50,000 invested in the cloning of animals could be utilized for the care of existing animals in shelters, or invested in programs for spaying and neutering homeless shelter pet populations.
Little Nicky reportedly had health problems during his life. These health problems were not proven to be related to the cloning process. His owner claims that the original Nicky never had the health problems that the clone had. The company that cloned Little Nicky believes that his health issues were acquired and not genetic.


Mireille Kamariza

Mireille Kamariza (born 1989) is a Burundian-born American bioscientist and Harvard Junior Fellow. Her research considers infectious diseases, the development of low cost point-of-care diagnostics and global health. In 2020 she was named as one of Chemical & Engineering News's Talented 12.
Early life.
Kamariza was born in Burundi a few years before the Burundi Civil War. Kamariza became interested in science as a child, and enjoyed reading books about planets. Girls rarely attend college in Burundi, but Kamariza enrolled at a government-managed Catholic school.
During Kamariza's childhood, she often had to move due to the ongoing civil war. Kamariza observed the ravages that infectious diseases such as AIDS and malaria have on already vulnerable populations. But whilst malaria and AIDS receive significant media attention and funding, they are not the most lethal conditions in Africa. In 2015, tuberculosis killed 1.4 million people, considerably more than AIDS, and there is still significant stigma surrounding the disease.
In 2006, Kamariza and her brothers moved to San Diego, California. Together they lived close to San Diego Mesa College, where Kamariza took classes alongside working to support herself. Saloua Saidane, one of her professors, noticed her talent and suggested that she focused on her education. Following Saidane's advice, Kamariza quit her job at Safeway.
Kamariza transferred and completed her bachelor's degree in biochemistry at the University of California, San Diego. At UCSD, Kamariza and her colleagues established a peer-to-peer mentoring program that paired transfer students with current UCSD students. Her efforts inspired other initiatives at UCSD, including supporting transfer students in identifying research opportunities. Her impact on UCSD was recognised by her undergraduate dean David Artis, who referred to Kamariza as one of his "all-time favorite students". She was awarded an American Chemical Society (ACS) internship to work at the ACS headquarters.
Education and research.
In 2012 Kamariza moved to the University of California, Berkeley for her graduate studies in cell biology. She applied to join the research group of Carolyn R. Bertozzi. After earning her master's degree, Kamariza joined Stanford University as a graduate student, still working in the Bertozzi laboratory. Here she developed a new point of care diagnostic device for tuberculosis (TB). Tuberculosis is caused by the "mycobacterium tuberculosis", a bacteria that has a cell wall so dense that it is difficult for drugs to penetrate. Trehalose is a chemical compound that is found in a range of living organisms that is used by "mycobacterium tuberculosis" as a scaffold. Kamariza developed DMN-Tre (4-"N,N"-dimethy-laminonaph-thal-i-mide-trehalose), a molecule that lights up when it is incorporated into the cell walls of mycobacteria. Her research was commercialised, and together with Bertozzi she founded OliLux Biosciences, a company that looks to develop low cost diagnostics for low-income countries. It was awarded a Bill & Melinda Gates Foundation grant to test their diagnostic devices in places with high levels of disease. She has tested it with small groups of patients in South Africa. In 2017 Kamariza was selected as one of "Fortune magazine"'s World's Most Powerful Women.
Kamariza was appointed a Harvard Junior Fellow at Harvard University in 2019. She examines topics regarding precision medicine in global health. She was named one of Chemical & Engineering News's Talented 12 in 2020.


British Biotech

British Biotech was a British-based biotechnology company founded as British Biotechnology Limited in 1986 by former G D Searle managers Keith McCullagh and Brian Richards.
It was the first British biotech company to be publicly listed when it was floated on 1 July 1992.
Controversy.
In 1996, despite having no compounds on or near the market, the company was temporarily valued at nearly $2.5 billion, largely on the basis of its two main development drugs: "marimastat" (a novel matrix metalloprotease inhibitor for cancer treatment) and "zacutex" (for pancreatitis). "Batimastat" (codename BB94) progressed as far as stage 3 in its clinical trial, although not orally bioavailable, there are other methods of administration, including transdermal.
In February 1998, Dr Andrew Millar was dismissed as Head of Clinical Research and went on to make allegations that "the Board were running a business plan consistent only with extreme and unfounded optimism". For example, the eponym Batimastat, "batty" means a crazy/eccentric person. Not a good selection. These events were the subject of an inquiry by the House of Commons Select Committee on Science and Technology in August 1998 which absolved Dr Millar of any responsibility for the company's problems.
Subsequent investigations by the Securities and Exchange Commission, Food and Drug Administration, London Stock Exchange and the European Medicines Evaluation Agency found that British Biotech had wilfully misled the public about the progress of marimastat and that unblinding data before the end of clinical trials does not necessarily invalidate the results. Marimastat underwent Phase III trials in collaboration with Schering-Plough Corporation.
Further development of zacutex was abandoned due to poor clinical trial results.
The corporate politics behind the downfall of British Biotech was later recorded for a BBC2 Series "Blood on the Carpet".
Disappearance.
In 2003, British Biotech merged with RiboTargets and then into Vernalis Group. The British Biotech company name disappeared after this merger and remaining staff integrated into the new Vernalis plc organisation in Winnersh, Berkshire.


Desulfoconvexum algidum

Desulfoconvexum algidum is a psychrophilic, strictly anaerobic and sulfate-reducing bacterium from the genus of Desulfoconvexum which has been isolated from cold marine sediments from Smeerenburgfjorden in Norway.


Louise Chow

Louise Tsi Chow () is a professor of biochemistry and molecular genetics at the University of Alabama at Birmingham and a foreign associate with the National Academy of Sciences, known for her research on the human papillomavirus. Her research contributed to the discovery of gene splicing, and in 1993, her collaborator, Richard J. Roberts, received the Nobel Prize for the research, leading some to assert that Chow should have received the honor as well.
Biography.
Chow was born in Hunan Province, Republic of China. Her father Chou Te-wei () was a well known economist who worked in the Ministry of Finance of the Republic of China on Taiwan.
She studied agricultural chemistry at National Taiwan University, graduating in 1965 before moving to California to pursue graduate studies in chemistry at the California Institute of Technology, earning her Ph.D in 1973. She then undertook post-doctoral training at the University of California, San Francisco, researching the monkey tumor virus SV40.
She and her husband, fellow scientist Thomas Broker, joined Cold Spring Harbor Laboratory in 1975. It was here that, in the process of studying the genetic organization, DNA transcription, and RNA translation of adenoviruses, she and her colleagues discovered RNA splicing in 1977. This finding led to her collaborator, Richard Roberts, winning the 1993 Nobel Prize in Physiology or Medicine (shared with Phillip Sharp from MIT whose team independently made the discovery). Many feel that Chow deserved a share of the prize (see Nobel Prize controversy).
In 1984, she took a job with the University of Rochester School of Medicine, studying the genome of the human papillomavirus (HPV). Chow became a professor at the University of Alabama at Birmingham (UAB) in 1993, studying genetics and virology, focusing on diseases such as cancer, cystic fibrosis, and AIDS.
At UAB, Chow developed a method to produce large amounts of one of the most dominant cancer-causing HPV strains, HPV-18, in the laboratory, enabling her and her team to study HPV's entire replicative cycle.
Nobel Prize controversy.
In 1993, her collaborator at Cold Spring Harbor Laboratory, Richard J. Roberts, was awarded the Nobel Prize, along with researcher Phillip Sharp, for the discovery of RNA splicing. Roberts called the award a "tribute" to his co-workers, including Chow. However, other scientists felt that Chow, who operated the electron microscope that allowed researchers to observe the splicing process, should have been included among the scientists awarded the Nobel Prize for the research. Chow told the Boston Globe that her contributions "were not trivial… it was a new type of experiment and needed to be designed and set up."


Mycothione reductase

In enzymology, a mycothione reductase () is an enzyme that catalyzes the chemical reaction
in "M. tuberculosis" and other actinomycetes.
The 2 substrates of this enzyme are mycothiol and NADPH, whereas 2 molecules of mycothione and NADP+ are formed as products.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is mycothiol:NAD(P)+ oxidoreductase. This enzyme is also called mycothiol-disulfide reductase.


Linusorb

Linusorbs are small biologically active cyclic peptides synthesized in flaxseed ("Linum usitatissimum") from two ribosome-derived precursors. The name is derived from Linum" usitatissimum" orbitide.
The molecules are very stable, not easily digested and stiff.
Nomenclature for Linusorb: [1–#-NαC],[#-Xaa,#-Xaa]-linusorb #.
The International Union of Pure and Applied Chemistry (IUPAC) Nomenclature for Natural Products supports the use of taxonomic names for the development of compound trivial names, while UniProt utilizes standard organism names as well as organism mnemonics in the naming of proteins. Linusorb product name according to Shim et al. (2015).
"Linkage" [1–#-NαC] Occurs between amino acid 1 and amino acid “#” through the α-amino group that a N-C cyclization of the core peptide. The en dash (–) is used and placed in square brackets.
"Modifications" [#-Xaa,#-Xaa] The notation utilizes a prefix code of 3, 4 characters. Specifies the position and type of modified amino acids in the peptide. Each modified amino acid is identified by its position in the core peptide sequence using abbreviations found in UniProt and IUPAC. A comma separates multiple post-translational modifications.
"Taxonomic name abbreviation" -linus The first three letters of the genus name and first two letters of the species name are used to identify the origin of the orbitide. Based on the list of species maintained by UniProt (http://www.uniprot.org/docs/speclist).
"Common suffix" (-orb) Short for orbitide.
Amino acid residue numbering (#) Residue numbering begins at the N-terminal-most amino acid residue of the orbitide, based on DNA sequence. Notation for any post-translational modifications start with the lowest number and proceed to the highest number. Where multiple identical modifications are present, they are grouped together as illustrated for Met groups in [1–8-NαC],[1,3-("R"s,"Ss")-MetO]-linusorb A1 (Table 1 and Figure 1; formerly cyclolinopeptide G, CLG). This more descriptive name for CLG reflects the complexity of fully and appropriately naming this compound as it contains the chiral amino acid methionine "S"-oxide. Clearly, what was formerly recognized as CLG is actually four distinct compounds. New full names for all “cyclolinopeptide” variants are suggested in Table 1.
Table 1. Elements of Linusorb Names.
Notes
"a"Proposed orbitide name: [1–#-NαC], linkage occurs between amino acid 1 and amino acid “#” through the α-amino group that a N-C cyclization of the core peptide. Use the en dash (–) as in ranges and place the square brackets; [#-Xaa,#-Xaa], methionine "S"-oxide has a chiral sulfur. Two diastereomers are designated as "S"s and "R"s. Identical amino acids substituents are numbered and grouped; lin-, Genus name is recognized by three letters or from UniProt list; -us-, species name is recognized by 2 letters or name from UniProt list; -orb, common suffix for orbitide.
"b"Name used in first literature description.
"c"The methionine residues of amino acid sequences are highlighted in Figure 1. Abbreviations of the methionine residues are MetO for methionine "S"-oxide and MetO2 for methionine "S","S"-dioxide.
"d"AFSQ01016651.1.
"e"AFSQ01011783.1 and AFSQ01009065.1.
"f"AFSQ01016651.1.


Jean Vance

Jean Vance is a British-Canadian biochemist. She is known for her pioneering work on subcellular organelles and for her discovery of a connection between the endoplasmic reticulum and the mitochondrial membrane. She is a Professor of Medicine at the University of Alberta, Canada and a Fellow of the Royal Society of Canada.
Education.
Vance earned her BSc in Chemistry from Bedford College, London, UK in 1964 and her Ph.D. from the University of Pittsburgh, USA in 1969, where she worked with Ronald Bentley. She performed postdoctoral work at the University of Pittsburgh and the University of California, San Diego.
Career.
After working at the University of British Columbia as a Lecturer, Vance joined the University of Alberta in 1987. She began to study the synthesis of the lipids that make up the subcellular membranes that divide the cell into compartments. At the time, the site(s) of synthesis of lipids and the mechanisms by which they were moved around the cell were mysterious. Working with a preparation of mitochondria, she made the surprising observation that rapid lipid synthesis occurred in a crude preparation containing additional membranes, but not in a highly purified mitochondrial fraction. This led her to hypothesize that a specialized membrane compartment, which she called Fraction X, might be responsible for the transfer of lipids from the endoplasmic reticulum to mitochondria. Although this idea was initially greeted with skepticism, Vance was able to reconstitute the transfer of newly made lipids to mitochondria in a cell-free system. She purified "Fraction X", renaming it the mitochondria-associated membrane (MAM) fraction, and showed that it contained highly active enzymes able to synthesize a variety of membrane components. She proposed that the MAM might function as a "membrane bridge" between the endoplasmic reticulum and the mitochondria. Although Vance's work was ahead of its time, it was rediscovered in the late 2000s when other researchers began to identify specific proteins, called tethers, that form the contact points between organelles. The mitochondria-endoplasmic reticulum bridge Vance originally identified is now named the endoplasmic reticulum membrane protein complex and has been shown to be important in the function, positioning and inheritance of mitochondria. Impaired contact between the endoplasmic reticulum and mitochondria has been suggested to underlie the pathology of several neurodegenerative diseases, including Alzheimer's disease. The newly appreciated importance of contacts among different subcellular organelles led in 2018 to the founding of a journal devoted to the area, "Contact," published by SAGE Publishing.
Vance has also worked on the transport of lipids and cholesterol to growing neurons. She discovered defects in cholesterol transport in neurons lacking the protein associated with Niemann–Pick disease type C, NPC1, and found that these defects can be addressed by treatment with cyclodextrin. She observed that growing neurons "in vitro" take up and use components from low-density lipoprotein and very low-density lipoprotein particles, and identified a role for lipoproteins provided by glial cells in stimulating nerve cell growth and protecting neurons from apoptosis.
In 2018 she was awarded the Wilhelm Bernhard International Lifetime Achievement Prize by the European Molecular Biology Organization.
Together with her husband and collaborator Dennis E. Vance, she co-edited the advanced textbook "Biochemistry of lipids, lipoproteins and membranes" from 1985 until the 5th edition in 2008.
Vance and her husband both elected to enrol in the University of Alberta's Transitional Retirement Program in 2017, planning to wind down their research over a three-year period. Their son, Russell Vance, is an investigator of the Howard Hughes Medical Institute and a faculty member at the University of California, Berkeley.


4-HO-MPT

4-Hydroxy-"N"-methyl-"N"-propyltryptamine, commonly known as 4-HO-MPT or meprocin, is a psychedelic drug in the tryptamine class of chemical compounds and is a higher homologue of the naturally occurring substituted tryptamine psilocin as well as being the 4-hydroxyl analog of MPT.
History.
4-HO-MPT was first synthesized and bioassayed by biochemist Alexander Shulgin and written about in his 1994 book "TiHKAL".
Dosage and duration.
For psychedelic effects, the dosage and duration are listed as "unknown" in TiHKAL.
Effects.
Very little data exists about the pharmacological properties, metabolism, and toxicity of 4-HO-MPT. In a single trial of 8 mg orally of 4-HO-MPT HCl from TiHKAL, it is described as producing visual distortion, vertigo, and slight insomnia.
Legal status.
4-HO-MPT is not scheduled by the United Nations' Convention on Psychotropic Substances.
United States.
4-HO-MPT is not scheduled at the federal level in the United States, but it is possible that 4-HO-MPT could legally be considered an analog of psilocin, in which case, sales or possession with intent for human consumption could potentially be prosecuted under the Federal Analogue Act.


Flavin prenyltransferase (UbiX)

UbiX is a flavin prenyltransferase, catalysing the addition of dimethylallyl-monophosphate (DMAP) (or dimethylallyl-pyrophosphate (DMAPP) ) onto the N5 and C6 positions of FMN culminating in the formation of the prenylated FMN (prFMN) cofactor. The enzyme is involved in the ubiquinone biosynthesis pathway in "E.coli" from where it gets its name. UbiX is associated with the UbiD enzymes as prFMN is utilised by UbiD enzymes in their function as reversible decarboxylases. Unusually for a prenyltransferase UbiX is not metal dependent.
Following the elucidation of prFMN's structure in the active site of Fdc1 from "aspergillus niger" (AnFdc1) the prenyltrasferase activity of UbiX was investigated. Incubation of UbiX from "P.aeruginosa" with oxidised FMN and DMAP followed by reduction with sodium dithionite lead to the formation of prFMNreduced. The same procedure followed by re-oxidation under aerobic conditions lead to prFMNradical. Anaerobic incubation of apo-AnFdc1 with prFMNreduced followed by exposure to oxygen lead to decarboxylase activity, however incubation with prFMNradical did not afford activity to apo-AnFdc1. This suggests that the prFMNreduced form can be correctly oxidised by UbiD/Fdc1 to the corresponding prFMNiminium (Figure 2).
UbiX Mechanism.
"P.aeruginosa" UbiX (PaUbiX) crystal structures revealed the DMAP substrate is positioned directly above the FMN isoalloxazine ring and that the N5-C1’ dimethylallyl adduct forms first as a prerequisite to formation of the C6-C3’ bond and creation of the fourth non-aromatic ring (Figure.1). Several conserved residues were found to be binding the DMAP phosphate group with the residue E140 suggested to act as a proton donor to enhance the phosphate leaving group. The study suggested that the two residues S15 and E49 play an important role in N5 deprotonation and N5-C1’ bond formation (Figure 1), the mutation E49Q severely affected PaUbiX’s ability to activate AnFdc1 and crystal structures of E49Q did not reveal a N5-C1’ bond within 1-5 seconds following reduction and rapid freezing, in contrast to wild type (WT) PaUbiX for which the N5-C1’ bond was observed within 1-5 seconds. This study was unable to trap any intermediates during formation of the C3’-C6 bond, but suggested C6 nucleophilic attack on the C3’ carbocation occurs concomitant with or following protonation of the C2’ via the bound phosphate. The resultant cyclohexadiene adduct was then postulated to form the final product via aromatisation concomitant with proton abstraction via S15 and E49. The mechanism suggested for PaUbiX is shown in Figure 1.
These findings were updated in 2019 with a new publication showing that the first step, the N5-C1' bond formation is likely to occur via an SN1 mechanism. This leads to the strict requirement for a substrate dimethylallyl moiety to initiate the reaction. The same paper showed that the N5 alkylation occurred whether it was a DMAP or DMAPP substrate in the DMAPP specific UbiX from aspergillus niger (AnUbiX), therefore this step is independent of the beta phosphate present in DMAPP. In the same AnUbiX enzyme they showed that the Fridel-Crafts alkylation of the flavin C6 only occurs using the DMAPP substrate. Mutations to the phosphate binding site of PaUbiX were also unable to form the C6-C3' bond, but could be rescued through the addition of phosphate. This confirmed that UbiX catalyses the formation of the C6-C3' bond through phosphate (and pyrophosphate) acid-base catalysis.