Characterizing Venom Variation in the Mexican Montane Pitvipers (Cerrophidion)

Hofmann, Erich P.                                                                                                         


Rautsaw, Rhett M.                                                                                                                                       Department of Biological Sciences

Clemson University

Clemson, South Carolina, USA


Grünwald, Christoph I.                                                                                                                                         Jones, Jason M.

Franz-Chávez, Héctor

Ahumada-Carrillo, Ivan T                                                                                                                               

Ramírez Chaparro, Ricardo AC                                                                                                                                                                    Villa del Álvarez, Colima, Mexico


de La Torre Loranca, Miguel Angel                                                                                                                 Instituto Lorancai

Km 32 Carretera Federal Orizaba-Zongolica Ocotepec                                                                                          Los Reyes, Veracruz, Mexico


Strickland, Jason L.

Mason, Andrew J.

Holding, Matthew L.*

Department of Biological Sciences                                                                                                                            Clemson UniversityClemson, South Carolina, USA


Borja, Miguel

Castañeda-Gaytán, Gamaliel                                                                                                                                      Facultad de Ciencias Biológicas                                                                                                                 Universidad Juárez del Estado de Durango

Av. Universidad s/n. Fracc. Filadelfia - C.P. 35070                                                                                               Gómez Palacio, Durango, Mexico


Rokyta, Darin R.

Department of Biological Science*                                                                                                                 

Florida State University                                                                                                                             Tallahassee, Florida, USA


Parkinson, Christopher L.                                                                                                                        

Department of Biological Sciences                                                                                                         Department of Forestry and Environmental Conservation                                                                                    

Clemson University

Clemson, South Carolina, USA 


Venom is highly adaptive, changing rapidly between species and between populations of the same species. Changes to venom are the result of adjustments in toxin gene expression and the underlying DNA sequence. However, the venom of many species remains uncharacterized, making it difficult to trace the evolutionary history of venom and provide adequate medical help to those bitten by uncharacterized species. Profiling toxin genes and their expression within and between species allows for the examination of venom variation and provides a better understanding of the full venom arsenal of a species. Here, we attempt to fill gaps in our understanding of venom evolution and variation by analyzing venom of three species of Cerrophidion from Mexico. We sequenced the venom-gland transcriptome for 12 individuals (six Cerrophidion godmani, three C. petlalcalensis, and three C. tzotzilorum) collected in southeastern Mexico, and tested for differences in the expression of toxin genes related to age class and locality. We found that the venom transcriptomes of these species are dominated by PLA2s and SVMPs, largely hemorrhagic toxins as expected, but individual variation was present in conspecific individuals. Both C. godmani and C. tzotzilorum displayed several toxins that were significantly differentially expressed between age classes, suggesting a possible ontogenetic shift. Interestingly, the most highly expressed PLA2 transcripts in C. godmani populations north and south of the Chiapan Depression were distinctly different, despite otherwise similar transcriptomic profiles. This might be evidence of local adaptation or early lineage diversification driving venom differences between these disjunct populations. Our data represent a broad examination of the venoms of Mexican Cerrophidion, characterizing the toxin gene repertoire of these species for the first time. Further sampling, proteomic confirmation, and additional analyses are underway to provide a more complete understanding of Cerrophidion venom evolution and variation across their range.

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