Snake Venom and Antivenom Pharmacology

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  SNAKE VENOM & ANTIVENOM Chemistry, Composition, Mechanisms and Pharmacology Abstract This integrated teaching session for Phase III MBBS students focused on the pharmacology and toxicology of snake venom and the principles of antivenom therapy. The lecture covered the chemistry, composition, mechanisms of action, and pharmacological effects of snake venoms and antivenoms. Rational use of antivenoms, indications, administration protocols, adverse reactions, and supportive management strategies were discussed. The session also highlighted the translational importance of venom-derived compounds in modern drug development. Recent advances in antivenom research, including recombinant human monoclonal antibodies, toxin-specific inhibitors, synthetic antibody technologies, and next-generation broad-spectrum antivenoms, were reviewed. Current discoveries and emerging approaches aimed at improving efficacy, safety, affordability, and accessibility of antivenom therapy were also explor...

Taxonomy, Phylogeny, and Size Evolution in the Spider Genus Megaraneus Lawrence, 1968 (Araneae: Araneidae)

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Taxonomy, Phylogeny, and Size Evolution in the Spider Genus Megaraneus Lawrence, 1968 (Araneae: Araneidae)

Abstract

Among terrestrial animals, spiders exhibit the most striking examples of sexual size dimorphism (SSD) but better understanding of its evolution requires improved taxonomy and phylogeny. Many sexually dimorphic spiders lack adequate description, phylogenetic placement, and natural history observations. In South Africa, we documented the natural history of a poorly known spider, Megaraneus gabonensis (Lucas, 1858), with extreme, female-biased SSD (eSSD, female:male approximately 4:1). Here, we redescribe M. gabonensis, place Megaraneus Lawrence, 1968 phylogenetically for the first time, assess whether the observed eSSD represents an independent evolutionary origin, and test whether the macroevolutionary pattern is better explained by male dwarfism or female gigantism. The recovered phylogenetic placement of Megaraneus in the araneid ‘backobourkiines’, a clade previously considered as restricted to East Asia and Australasia, extends the range of this clade to the Afrotropics. We find that eSSD was present in the common ancestor of the ‘backobourkiines’, with further increases in female body length occurring independently in Megaraneus, Backobourkia Framenau, Dupérré, Blackledge & Vink, 2010, and the currently misplaced Parawixia dehaani (Doleschall, 1859). We conclude that the evolution of eSSD reflects a complex pattern of sex-specific size changes across spider phylogeny, but that in Megaraneus it results from female gigantism.

Čandek, K., Turk, E., Yu, K., Gregorič, M., Framenau, V. W., Agnarsson, I., & Kuntner, M. (2025). Taxonomy, Phylogeny, and Size Evolution in the Spider Genus Megaraneus Lawrence, 1968 (Araneae: Araneidae). Insects, 16(10), 992. https://doi.org/10.3390/insects16100992