A new study in the journal Molecular Biology and Evolution offers a genetic clue to how woodrats resist rattlesnake venom. Earlier work showed that a SERPIN gene, SERPINA1, can inhibit European rattlesnake venom; the new research focused on a related but less understood gene, SERPINA3.
Researchers found that woodrats carry 12 copies of SERPINA3. These extra copies arose through tandem duplication, a process in which an extra gene copy is inserted into the genome while the original gene keeps its normal role and the new copy can evolve a different function. The team, led by Matthew Holding and co-led by Meilyn Ward in David Ginsburg’s lab at the University of Michigan Life Sciences Institute, tested proteins from each of the 12 genes using venom from local rattlesnakes.
Many SERPINA3 proteins bound directly to venom components and blocked toxic effects, though activity varied. Some proteins did not interact with the venom, and one inhibited two distinct venom components. The authors suggest these duplications may be part of a coevolutionary response. The study was supported by the National Institutes of Health and the University of Michigan’s Honors Summer Fellowship. Authors include Matthew Holding, Meilyn Ward, Laura Haynes, David Ginsburg, Mark Margres, and Marjorie Matocq.
Difficult words
- inhibit — stop or slow a biological or chemical actioninhibited
- tandem duplication — a nearby repeat of a gene in DNA
- protein — molecule made of amino acids with functionsproteins
- component — one part of a mixture or a systemcomponents
- coevolutionary — linked evolution between two interacting species
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How might having extra copies of a gene help woodrats survive rattlesnake bites? Give two short reasons.
- Why could it be useful that some SERPINA3 proteins do not interact with venom while others do?
- Can you give another example of animals evolving defenses against predators? Describe it in two or three sentences.
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