Hidden diversity in plain sight: four new species of Nemesia (Araneae: Mygalomorphae) from the Córdoba Province of Spain

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  Hidden diversity in plain sight: four new species of Nemesia (Araneae: Mygalomorphae) from the Córdoba Province of Spain Abstract A taxonomic revision of the species of Nemesia Audouin, 1826, distributed in the vicinity of Córdoba City, southern Spain, is presented. Four new species are described: Nemesia morana sp. nov. (female), N. kodama sp. nov. (male and female), N. rosae sp. nov. (male and female), and N. tamajoni sp. nov. (male and female). These species are distinguished by distinct morphological characters, including the shape of the spermathecae, palpal bulbs, and spinnerets, as well as by burrow architecture. Fieldwork was conducted across two of the three major habitat types in the region—the humid, forested mountains of Sierra Morena and the croplands and riparian forests of the Guadalquivir Valley—while the third, the “campiña”, which is mainly composed of agricultural landscapes, remains poorly explored. Sampling methods included pitfall trapping and the direct e...

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