Beyond Venom and Constriction: Bite Performance and Trophic Ecology in the Genus Drymarchon

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  Beyond Venom and Constriction: Bite Performance and Trophic Ecology in the Genus Drymarchon Abstract Snakes exhibit extreme cranial kinesis that facilitates ingestion of prey with large cross-sectional area, but this ability is widely predicted to reduce bite performance due to decreased structural rigidity. Consequently, most large-bodied snakes rely on envenomation or constriction to subdue prey prior to ingestion. Species within the genus Drymarchon represent a notable exception: these large, non-venomous, non-constricting snakes routinely consume a wide range of prey, including large and potentially dangerous vertebrates, using only simple seizing and pinioning behaviors. Here, we quantify bite performance in three species of Drymarchon ( D. corais, D. couperi, and D. melanurus ), examine morphological predictors of biting performance, compare biting pressure to constriction pressure in similarly sized snakes, and synthesize dietary records across the genus. Our results sh...

Crotoxin B from the South American Rattlesnake Crotalus vegrandis Blocks Voltage-Gated Calcium Channels Independent of Its Intrinsic Catalytic Activity

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By Patrick JEAN / muséum d'histoire naturelle de Nantes - Muséum d'histoire naturelle de Nantes (archive copy at the Wayback Machine), Copyrighted free use, https://commons.wikimedia.org/w/index.php?curid=29697

Crotoxin B from the South American Rattlesnake Crotalus vegrandis Blocks Voltage-Gated Calcium Channels Independent of Its Intrinsic Catalytic Activity

Abstract

Neurotoxicity following South American Crotalus rattlesnake bite is primarily caused by crotoxin, the most abundant component in their venom. Despite the central role of voltage-gated calcium channels (CaV) in neurotransmission, direct targetability by crotoxin has been poorly explored. Crotoxin is a non-covalent heterodimer formed by an acidic subunit (CA) and a basic toxic phospholipase A2 subunit (CB). Here, we chromatographically isolated the CB subunit from Crotalus vegrandis and studied its effect on CaV heterologously expressed in tsA201 cells using the whole-cell patch-clamp technique. Mass spectrometry analysis identified a protein that matched with 97% sequence coverage the CBc isoform from Crotalus durissus terrificus. Isolated CB exhibited moderate phospholipase activity that was not correlated to its cytotoxic effect on cultured tsA201 cells. Using Ba2+ as a charge carrier to prevent the enzymatic activity, we found that CB inhibited currents mediated by the N-type CaV2.2 and CaV1.2 L-type calcium channels, in a dose–dependent manner, with higher potency for the latter, and negligible changes in the voltage dependence of channel activation. Our results reveal a novel phospholipase-independent biological activity and a molecular target of CB providing new insights into the pathophysiology of Crotalus snakebite envenoming with potential clinical therapeutic implications.

Eicheldinger, M., Castilla, F., Jordan, N., & Hidalgo, P. (2026). Crotoxin B from the South American Rattlesnake Crotalus vegrandis Blocks Voltage-Gated Calcium Channels Independent of Its Intrinsic Catalytic Activity. Toxins, 18(1), 36. https://doi.org/10.3390/toxins18010036