To corroborate the ontogenetic shift in the venom composition of the Mexican Black-tailed Rattlesnake (Crotalus molossus nigrescens) previously reported through the census approach, we evaluated the shift in the protein profile, lethality, and proteolytic and phospholipase activities of four venom samples obtained in 2015, 2018, 2019, and 2021 from one C. m. nigrescens individual (CMN06) collected in Durango, Mexico. We demonstrated that the venom of C. m. nigrescens changed from a myotoxin-rich venom to a phospholipase A 2 and snake venom metalloproteinase-rich venom. Additionally, the proteolytic and phospholipase activities increased with age, but the lethality decreased approximately three times.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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