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Expression of Venom Gene Homologs in Diverse Python Tissues Suggests a New Model for the Evolution of Snake Venom

Reyes-Velasco, Jacobo, Card, Daren C, Andrew, Audra L, Shaney, Kyle J, Adams, Richard H, Schield, Drew R, Casewell, Nicholas ORCID:, Mackessy, Stephen P and Castoe, Todd A (2014) 'Expression of Venom Gene Homologs in Diverse Python Tissues Suggests a New Model for the Evolution of Snake Venom'. Molecular Biology and Evolution, Vol 32, Issue 1, pp. 173-183.

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Snake venom gene evolution has been studied intensively over the past several decades, yet most previous studies have lacked the context of complete snake genomes and the full context of gene expression across diverse snake tissues. We took a novel approach to studying snake venom evolution by leveraging the complete genome of the Burmese python, including information from tissue-specific patterns of gene expression. We identified the orthologs of snake venom genes in the python genome, and conducted detailed analysis of gene expression of these venom homologs to identify patterns that differ between snake venom gene families and all other genes. We found that venom gene homologs in the python are expressed in many different tissues outside of oral glands, which illustrates the pitfalls of using transcriptomic data alone to define "venom toxins." We hypothesize that the python may represent an ancestral state prior to major venom development, which is supported by our finding that the expansion of venom gene families is largely restricted to highly venomous caenophidian snakes. Therefore, the python provides insight into biases in which genes were recruited for snake venom systems. Python venom homologs are generally expressed at lower levels, have higher variance among tissues, and are expressed in fewer organs compared with all other python genes. We propose a model for the evolution of snake venoms in which venom genes are recruited preferentially from genes with particular expression profile characteristics, which facilitate a nearly neutral transition toward specialized venom system expression.

Item Type: Article
Subjects: QU Biochemistry > Genetics > QU 470 Genetic structures
QU Biochemistry > Genetics > QU 475 Genetic processes
QW Microbiology and Immunology > Antigens and Antibodies. Toxins and Antitoxins > QW 630 Toxins. Antitoxins
WD Disorders of Systemic, Metabolic or Environmental Origin, etc > Animal Poisons > WD 410 Reptiles
Faculty: Department: Biological Sciences > Department of Tropical Disease Biology
Digital Object Identifer (DOI):
Depositing User: Mary Creegan
Date Deposited: 15 Dec 2014 12:37
Last Modified: 06 Feb 2018 13:08


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