Date of Award

12-2022

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Committee Chair/Advisor

Christopher L. Parkinson

Committee Member

Michael S. Caterino

Committee Member

Matthew H. Koski

Abstract

Most traditional research on snake venoms has focused on front-fanged snake families (Viperidae, Elapidae, and Atractaspididae). However, venom is now generally accepted as being a much more broadly possessed trait within snakes, including species traditionally considered harmless. Unfortunately, due to historical inertia and methodological challenges, the toxin repertoires of non-front-fanged snake families (e.g., Colubridae, Dipsadidae, and Natricidae) have been heavily neglected despite the knowledge of numerous species capable of inflicting medically relevant envenomations. Integrating proteomic data for validation, we perform a de novo assembly and analysis of the Duvernoy’s venom gland transcriptome of the Central American Road Guarder (Dipsadidae: Xenodontinae: Conophis lineatus), a species known for its potent bite. We identified 28 putative toxin transcripts from 13 toxin families in the Duvernoy’s venom gland transcriptome, comprising 63.7% of total transcriptome expression. In addition to ubiquitous snake toxin families, we proteomically confirmed several atypical venom components. The most highly expressed toxins (55.6% of total toxin expression) were recently described snake venom matrix metalloproteases (svMMPs), with 48.0% of svMMP expression contributable to a novel svMMP isoform. We investigate the evolution of the new svMMP isoform in the context of rear-fanged snakes using phylogenetics. Finally, we examine the morphology of the venom apparatus using μCT and explore how the venom relates to autecology and the highly hemorrhagic effects seen in human envenomations. Importantly, we provide the most complete venom characterization of this medically relevant snake species to date, producing insights into the effects and evolution of its venom, and point to future research directions to better understand the venoms of ‘harmless’ non-front-fanged snakes.

Comments

The material of this thesis has been published in the following article:

Schramer, T. D., Rautsaw, R. M., Bayona Serrano, J. D., Nystrom, G. S., West, T. R., Ortiz-Medina, J. A., Sabido-Alpuche, B., Meneses-Millán, M., Borja, M., Junqueira de Azevedo, I. L. M., Rokyta, D. R., & Parkinson, C. L. (2022). An integrative view of the toxic potential of Conophis lineatus (Dipsadidae: Xenodontinae), a medically relevant rear-fanged snake. Toxicon, 205(2022), 38–52. https://doi.org/10.1016/j.toxicon.2021.11.009

Fig1_Map.pdf (7946 kB)
Figure 1

Fig2_DVGtranscriptome.pdf (16132 kB)
Figure 2

Fig3_svMMPs.tif (62519 kB)
Figure 3

Fig4_Morphology.jpg (5189 kB)
Figure 4

Author ORCID Identifier

0000-0002-4553-8002

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