They rattle as warning, but during the hunt their strike is silent and sudden. Any rabbit or mouse targeted by a rattlesnake is doomed—the snake’s bite carries a paralyzing venom. The toxins in this venom are proteins encoded by a large gene family that arose by gene duplication. In the July issue of GENETICS, Margres et al. tackle two models of how gene family expansion gets started by analyzing individual variation in a rattlesnake toxin gene family. They find that the most important factor in gene family growth via duplication was selection pressure to increase protein expression level.
Gene families are groups of similar genes born through duplication and are extremely common in eukaryote genomes. The different genes in a family often have sequence changes that allow them to carry out distinct functions, but additional gene copies also mean a higher overall expression level. Theoretically, both of these consequences of gene family expansion can be adaptive, but it’s unclear which is more important during the initial stages of gene family evolution. To clarify this question, Margres et al. use the rattlesnake gene family that encodes myotoxin, a component of venom.
Venom is a useful model because the connection between protein expression and phenotype is clear: the more protein is expressed, the more potent the effect. And importantly, there is still variation in the size of the myotoxin gene family among rattlesnakes. For this study, the authors collected venom and blood samples from over a hundred live-caught, wild rattlesnakes from across the Southeastern US. The number of myotoxin gene copies in these snakes ranged from zero to nearly 50, with a corresponding increase in myotoxin protein expression in venom. However, only four individuals carried gene copies with a nucleotide polymorphism within the key exons, indicating that the duplicate copies are essentially identical.
Clearly, these carbon-copy myotoxin genes aren’t carrying out different functions. The direct relationship between venom protein level and the number of myotoxin gene copies shows that the expansion of this gene family is likely driven by selection for increased expression and thus stronger venom. Animals as diverse as platypuses and cone snails use venom for hunting and defense. This study not only shows how this fascinating and frightening adaptation evolves, but it also provides a glimpse of the forces that can trigger a gene to start down the road of expansion—and ultimately—diversification.
CITATION
Selection To Increase Expression, Not Sequence Diversity, Precedes Gene Family Origin and Expansion in Rattlesnake Venom
Mark J. Margres, Alyssa T. Bigelow, Emily Moriarty Lemmon, Alan R. Lemmon and Darin R. Rokyta
GENETICS July 1, 2017 vol. 206 no. 3 1569-1580; https://doi.org/10.1534/genetics.117.202655
http://www.genetics.org/content/206/3/1569
Katie is a science writer at GSA. She did her PhD work on the evolutionary consequences of genetic conflict in fruit flies at the University of Georgia.
View all posts by Katie Pieper »Read more in
-
Hongyu Zhao joins GENETICS as new Senior Editor
A new senior editor is joining GENETICS in the Statistical Genetics and Genomics section. We’re excited to welcome Hongyu Zhao to the editorial team. Hongyu ZhaoSenior Editor Hongyu Zhao is the Ira V. Hiscock Professor of Biostatistics, Professor of Genetics, and Professor of Statistics and Data Science at Yale University. He received his BS in…
-
GSA Member Julio Molina Pineda Receives DeLill Nasser Award, Shines at TAGC 2024
“At any career stage, the GSA membership is an amazing investment for any genetics professional!” Julio Molina Pineda is a PhD Candidate in Cell and Molecular Biology and a Research Assistant at the University of Arkansas, and a Doctoral Academy Fellow at the Lewis Lab. In 2023, Julio was awarded the DeLill Nasser Award for…
-
In Memoriam: Ellsworth Herman Grell (1932–2023), a pioneer of Drosophila genome engineering and annotation
Ellsworth (Ed) Grell blessed the Drosophila community through three enduring legacies: as a pioneer of chromosome mechanics, as a primary organizer and synthesizer of genetic knowledge in Drosophila, and as a graceful mentor to those fortunate to have known him personally. Ed grew up in rural Nebraska, completed his undergraduate studies at Iowa State, and…
-
Congratulations to the #Fungal24 Poster Award winners!
We are pleased to announce the recipients of the GSA Poster Awards for posters presented at the 32nd Fungal Genetics Conference! Undergraduate and graduate student members of GSA were eligible for the awards, and a hard-working team of judges made the determinations. Congratulations to all! Felicia Ebot Ojong, The University of Georgia My research is focused…
-
Poster presentation tips for TAGC 2024
You’ve been selected to present a poster at The Allied Genetics Conference 2024 in March—you’ve celebrated, made plans to attend, now what? This is an exciting opportunity to showcase your research and engage with fellow members of the genetics community, so you want to make sure you’re prepared. We wanted to offer you some tips…
-
Maximize your TAGC 2024 experience
A guide to all that National Harbor & DC have to offer Are you joining us for The Allied Genetics Conference 2024 in March? Make the most of your #TAGC24 experience in National Harbor! We know the science will keep you busy, but you deserve to unwind and have some fun, so we’ve curated a…
-
Early Career Leadership Spotlight: Sarah Petrosky
We’re taking time to get to know the members of the GSA’s Early Career Scientist Committees. Join us to learn more about our early career scientist advocates. Sarah PetroskyMultimedia SubcommitteeUniversity of Pittsburgh Research Interest I am interested in understanding adaptation that has been happening recently in populations by dissecting the ways that genes underlying an adaptation…
-
TAGC 2024 Early Career Award Winners
GSA is pleased to announce the winners of the early career awards presented at The Allied Genetics Conference 2024. These awards are specific to particular TAGC communities and recognize early career scientists’ outstanding work on their respective research organisms. The awardees will present their talks in keynote sessions at TAGC 2024. Don’t miss the opportunity…
-
Preeminent geneticists recognized with revamped GSA Awards
In 2022, GSA’s Board of Directors launched an audit to review the five major awards conferred by the Society. Today, we are thrilled to announce the recipients of the reimagined GSA Awards, including the new Genetics Society of America Early Career Medal. The scientists honored this year are recognized by their peers for their outstanding…
-
Fly Board funds outreach programs to spread the word about Drosophila research
In 2020, the Fly Board voted to use part of its reserve fund to support efforts to increase trainee participation as well as equity and diversity in the Drosophila community. An awards committee decides how the money will be spent each year, and from 2020–2022, the committee posted a very broad call for applications from…
-
New members of the GSA Board of Directors: 2024–2026
We are pleased to announce the election of four new leaders to the GSA Board of Directors: 2024 Vice President/2025 President Brenda Andrews Professor, University of Toronto It’s an honor to continue my association with the Society by serving as Vice President of the Board of Directors. I have broad knowledge of the ongoing activities…