 Johannesson 2013), and both male-and female-biased genes show elevated rates of evolution in brown alga (Lipinska et al. 2015).
In order to confirm the generality of this pattern across fish, we tested the evolutionary rate of sex-biased genes in the stickleback lineage by comparing threespine and ninespine sticklebacks which diverged roughly 13 Mya (Bell et al. 2009). The convergence in pattern of evolutionary rates for both female-and male-biased genes between zebrafish and stickleback lineages, which last shared a common ancestor roughly 290 Mya (Steinke et al. 2006), suggests that this pattern may be representative for fishes in general. This is also supported by convergent results from a small-scale study in the guppy (Sharma et al. 2014).
The current evidence is unclear whether rapid rates of evolution for sex-biased genes observed in other organisms is due to positive selection (Proschel et al. 2006), perhaps related to sexual selection or sperm competition (Ellegren and Parsch 2007), or is due to relaxed constraint and genetic drift (Harrison et al. 2015;Dapper and Wade 2016). We used codon-bias, tissue-specificity and signatures of selection on coding sequence to differentiate these two potential forces. We observed that both male-biased genes and female-biased genes exhibiting reduced optimal codon usage compared to unbiased genes. The preferential use of a subset of synonymous codons (codon bias) is a prevalent phenomenon in a wide range of species (Akashi and Eyre-Walker 1998;Akashi 2001;Duret 2002), including vertebrates (Doherty and McInerney 2013;Ma et al. 2014). The "preferred codons" are generally assumed to arise as a result of natural selection favoring efficient and accurate translation (Duret and Mouchiroud 1999; Duret 2000). However, a previous study found that male-biased genes in Drosophila, which evolved faster than female-biased and unbiased genes, have significantly less codon bias than both female-biased and unbiased genes (Hambuch and Parsch 2005), which indicated either reduced efficacy of selection for optimal codon usage or recent disturbance of optimal codon usage due to positive selection.
Additionally, we find that both male-and female-biased genes tend to have more tissue-specific expression relative to unbiased genes. In general, broadly expressed genes tend to have more complex functional roles and undergo stronger functional constraints, thus evolve slower than genes with limited expression (Duret and Mouchiroud 2000). Therefore, this parallel reduction in expression breadth for both maleand female-biased genes in fishes may also serve as one of the possible reasons underlying their faster evolutionary rates. However, it should be noted that only weak correlation exists between expression breadth and evolutionary rate, implying that relaxed functional constraints may not be the unique driving force of evolutionary rates.
Finally, our analysis of divergence and polymorphism data indicate that a greater proportion of male-and female-biased genes show evidence of positive selection when compared to unbiased genes. The potential role of positive selection is also indicated by our DoS values for sex-biased genes, which were higher than for unbiased genes.
There are several reasons that may contribute to this symmetry of accelerated evolution for both male-and femalebiased genes. First, zebrafish does not exhibit much morphological sexual dimorphism (Spence et al. 2008), which may either result in less sexual selection for both male-biased and female-biased genes simultaneously, or lead to more strong sexual selection for both male-and female-biased genes simultaneously. Considering the faster evolution for both maleand female-biased genes, we think the latter would be more logical. Another possible reason for the faster evolution rates for both male-and female-biased genes in fishes may be that both male-and female-biased genes tend to have restricted breadth of expression pattern relative to unbiased genes. In general, broadly expressed genes tend to have more complex functional roles and undergo stronger functional constraints, thus to evolve slower than genes with limited expression (Duret and Mouchiroud 2000). Therefore, this parallel reduction in expression breadth for both male-and female-biased genes in fishes may also serve as one of the possible reasons underlying their faster evolutionary rates. Furthermore, this symmetry of accelerated evolution for both male-and female-biased genes may also be driven by external fertilization in fishes. Compared with internal fertilization in mammals, Drosophila, and birds, fishes need to produce much more viable eggs, thus female may be undergone stronger selection, which may drive faster evolution for female-biased genes.
The codon usage, tissue-specificity and signatures of selection tests reveal a complex pattern, where both positive selection and relaxed constraints may both contribute to the accelerated rates of evolution observed for sex-biased genes. This complex pattern may vary across distantly related groups, explaining why work in Drosophila has recovered stronger signatures of selection in male-biased genes (Proschel et al. 2006), whereas studies in adult birds (Harrison et al. 2015) and humans (Gershoni and Pietrokovski 2014) reveals patterns more consistent with relaxed evolutionary constraint and genetic drift. Given this complex, clade-specific pattern, as well as recent concerns about how expression-bias might alter mutation-selection dynamics (Dapper and Wade 2016), data from more species are needed to resolve this debate.Mr. Casanova says that "analytics are the foundation!"
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Originally written by Eric Peterson on February 21, 2006
I’m keeping up with a post-analytics Xavier Casanova and he just posted a nice piece about how he plans on staying true to his roots, thusly preserving his street cred. I was worried there for a moment, that one of the best-and-brightest was going to turn his back on all he’d done and manage his new business from the gut.
Phew.
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-You make second chances happen at Gloucester-Mathews Humane Society every day.
Jonah came to GMHS as a scared stray cat in January after being picked up by Gloucester County Animal Control. A handsome 10 lbs., three-year-old brown tabby, Jonah had the tiniest kitten-like meow. He would chat with visitors and rub his body on the glass of his cage to be petted, but was afraid to be touched.
Jonah wanted to be social but did not know how. After three months in our care, he continued to take his time warming up. We thought a change might help, so he was transferred to one of our adoption-guaranteed rescue groups through our Highway to Home program.
Upon his arrival at our partner shelter, Jonah joined his foster family, who, along with their older cat Marius, immediate...The Gallup Community Based Outpatient Clinic (CBOC) is designed to deliver primary care services to eligible Veterans.
Gallup is the destination for outdoor adventures, culture seekers, and art lovers. This is as real and authentic as it gets- Native American Culture, steeped in tradition, and a town surrounded by some of the best outdoor recreation destinations and trails in the Southwest.
This Buffalo Chicken Quesadilla recipe is one of my favorite finds! Has a great combination of ingredients creating awesome flavors!
Heat a large skillet over medium heat. In a medium bowl, mix together chicken and hot sauce until chicken is evenly coated; set aside. Butter one side of your tortilla. Flip the tortilla over and spread cream cheese on half of the un-buttered side. Place the tortilla in the skillet, buttered side down. Do not fold the tortilla over yet. Add bleu cheese crumbles on top of the cream cheese. Top cheeses with chicken, and jack cheese. Fold tortilla over filling. Cook until tortilla is browned on each side and jack cheese has melted. Cut into pieces and serve warm. Top with sour cream. You can garnish with a little chopped fresh or dried chives for some color, if you like too. NOTE Don't not overdo the cheese. Can become too cheesy and little of the buffalo wing flavor you want. A little Frank's Hot Sauce mixed with melted butter would make a good dipping sauce. I also would have more blue cheese dressing on the side.Dayna Shong, 39, works as an inpatient coder at Regions Hospital in Saint Paul, Minnesota, and is the winner of a GetEducated.com $1,000 Excellence in Online Education Scholarship. She will use the free college grant to pursue an online bachelor of science in health degree at Dakota State University.
After landing a job in retail, which paid the bills but did not provide a lot of personal satisfaction, Shong began looking through an occupational handbook at the library in search of a more satisfying career. Health administration immediately sparked her interest. In the fall of 2002, she signed up for an online course in Medical Terminology.
“I decided to take the most difficult class I could find to prove myself during my first semester. I studied harder than I ever have in my life,” explains Shong. “To this day, this is my favorite class. I found studying about anatomy, physiology, procedures, and vocabulary fascinating. I was hooked from day one.”She continues, “I earned an A in the class, thoroughly enjoyed myself, and realized that I was able to handle being in school while working full time.” After a positive experience with her first online course, Shong was convinced that online education would offer the best opportunities for her to pursue a bachelor of health degree. Shong is also grateful for the support and inspiration from her parents, as they have become driving factors to her success in distance learning.
Accreditation was the highest priority for Shong when choosing Dakota State University to pursue higher education. The Health Information Administration program is fully