Behavioral evidence for two-stage sleep in spiders

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  Behavioral evidence for two-stage sleep in spiders Abstract Sleep is a fundamental behavioral state found across the animal kingdom, yet most of what we know about sleep is heavily vertebrate-biased. Studies are scarce or nonexistent in all but a few invertebrate lineages. A recent study of an REM sleep-like behavior in a jumping spider has reported unexpected parallels to sleep expression in vertebrates. So far, experimental evidence that these behavioral indicators truly represent sleep was lacking in spiders. Here, we present a comprehensive investigation into sleep behavior in the spider Portia fimbriata (Salticidae). We demonstrate diurnal activity, a free-running circadian rhythm, robust sleep architecture, regularly occurring REM-like behaviors, elevated arousal thresholds during those REM-like states, as well as rebound effects following sleep disruption. We conclude that the behavior we observe in spiders is behavioral sleep, providing evidence for an REM-like sleep sub...

Lipidomics of Bothrops atrox and Crotalus durissus ruruima venoms, the two major viperids involved in human envenomings in the Brazilian Amazon

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Lipidomics of Bothrops atrox and Crotalus durissus ruruima venoms, the two major viperids involved in human envenomings in the Brazilian Amazon

Abstract

Recent investigations into the lipid constituents of snake venoms have yielded intriguing findings. Bothrops atrox and Crotalus durissus ruruima are the primary species responsible for snakebite envenomation in the Brazilian Amazon. However, the lipid compounds present in their venoms remain unknown. To address this gap, a lipidomic approach based on LC–HRMS (Liquid Chromatography–High-Resolution Mass Spectrometry) was employed to profile the lipid classes, subclasses, and species in the venoms of B. atrox and C. d. ruruima (yellow and white variations). The venom of B. atrox and the yellow variant of C. d. ruruima showed comparable profiles, with higher proportions of glycerolipids (55% and 46%, respectively) and glycerophospholipids (31% and 37%, respectively). In contrast, the white venom of C. d. ruruima showed a higher sphingolipid content (51%). Lipidomic analysis revealed multi-lipid species, with a high abundance of lipids from the subclasses sphingomyelin, phosphatidylcholine, monoalkylglycerol, and triacylglycerol, as well as monoacylglycerol, cardiolipins, glycerophosphoinositol, N-acylphosphatidylethanolamine, and cholesteryl esters. The lipids annotated are known to play diverse biological roles, particularly in cellular structure and signaling. This study is the first to characterize the lipid components in the venom of these snake species, contributing to a deeper understanding of their chemical composition and opening new avenues for investigating the roles of these compounds in snake venom.

Maciel, J.B., Nardini, V., Carvalho, N.S. et al. Lipidomics of Bothrops atrox and Crotalus durissus ruruima venoms, the two major viperids involved in human envenomings in the Brazilian Amazon. Arch Toxicol (2025). https://doi.org/10.1007/s00204-025-04200-2