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Squeezers and leaf-cutters: differential diversification and degeneration of the venom system in toxicoferan reptiles

Authors :
David Morgenstern
Darryl L. Whitehead
Nicolas Vidal
Jordan Debono
Glenn F. King
Holger Scheib
Sandy Pineda Gonzalez
Timothy N.W. Jackson
Eivind A. B. Undheim
Agostinho Antunes
Luke Cadwallader
Rob J.A. Nabuurs
Bryan G. Fry
Ivan Koludarov
Alun Jones
Syed Abid Ali
Iwan Hendrikx
Louise van der Weerd
Tim Ruder
Kim Roelants
Kartik Sunagar
Amphibian Evolution Lab
Source :
Vrije Universiteit Brussel, Molecular and Cellular Proteomics, 12(7), 1881-1899

Abstract

Although it has been established that all toxicoferan squamates share a common venomous ancestor, it has remained unclear whether the maxillary and mandibular venom glands are evolving on separate gene expression trajectories or if they remain under shared genetic control. We show that identical transcripts are simultaneously expressed not only in the mandibular and maxillary glands, but also in the enigmatic snake rictal gland. Toxin molecular frameworks recovered in this study were three-finger toxin (3FTx), CRiSP, crotamine (beta-defensin), cobra venom factor, cystatin, epididymal secretory protein, kunitz, L-amino acid oxidase, lectin, renin aspartate protease, veficolin, and vespryn. We also discovered a novel low-molecular weight disulfide bridged peptide class in pythonid snake glands. In the iguanian lizards, the most highly expressed are potentially antimicrobial in nature (crotamine (beta-defensin) and cystatin), with crotamine (beta-defensin) also the most diverse. However, a number of proteins characterized from anguimorph lizards and caenophidian snakes with hemotoxic or neurotoxic activities were recruited in the common toxicoferan ancestor and remain expressed, albeit in low levels, even in the iguanian lizards. In contrast, the henophidian snakes express 3FTx and lectin toxins as the dominant transcripts. Even in the constricting pythonid and boid snakes, where the glands are predominantly mucous-secreting, low-levels of toxin transcripts can be detected. Venom thus appears to play little role in feeding behavior of most iguanian lizards or the powerful constricting snakes, and the low levels of expression argue against a defensive role. However, clearly the incipient or secondarily atrophied venom systems of these taxa may be a source of novel compounds useful in drug design and discovery.

Details

Database :
OpenAIRE
Journal :
Vrije Universiteit Brussel, Molecular and Cellular Proteomics, 12(7), 1881-1899
Accession number :
edsair.doi.dedup.....f356007e2e344a088a5827e7acac892b