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...

Inhibitory effects of 6-O-palmitoyl-l-ascorbic acid (ASC16) on the enzymatic activity of Bothrops alternatus venom

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By Cláudio Timm - https://www.flickr.com/photos/cdtimm/4267955250/, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=13205355

Inhibitory effects of 6-O-palmitoyl-l-ascorbic acid (ASC16) on the enzymatic activity of Bothrops alternatus venom

Abstract

In the anti-venom production process, it is essential to use whole venom during immunization to generate specific antibodies capable of neutralizing all venom components. However, efforts are being made to improve the traditional immunization process by reducing the toxic effects of venom components on the immunized animals while ensuring an optimal immune response in accordance with good manufacturing practices. In this context, we aimed to evaluate the capacity of ASC16 to inhibit the enzymatic activity of the main components of B. alternatus venom. In vitro studies were conducted to evaluate the inhibitory effect of ASC16 on metalloproteinases (SVMP), serine proteinases (SVSP) and phospholipases A2 (PLA2) using specific substrates. In vivo assays measured edema-forming activity, and histological analysis with hematoxylin and eosin staining were performed. Additionally, hemorrhage inhibition was tested using a murine model. In silico studies were also carried out using bothropasin as a model. The results of enzyme inhibition showed that ASC16 significantly inhibited SVMP (49.31% ± 0.62), SVSP (63.11 ± 3.86%) and PLA2 activity (36.52% ± 0.09). ASC16 did not reduce edema but it significantly inhibited hemorrhage (66.32%). In silico analysis suggested that ASC16’s hydrophobic portion binds to critical residues involved in catalysis of the SVMP (Glu146 and His145), while the hydrophilic fraction also interacts with the protein (Pro109, Thr110, Gly112, and Tyr132). These findings position ASC16 as a promising candidate for use as an additive inhibitor in adjuvant formulations in antivenom immunization schemes for B. alternatus.

Maslovski, F., Pereañez, J.A., Hernández, D. et al. Inhibitory effects of 6-O-palmitoyl-l-ascorbic acid (ASC16) on the enzymatic activity of Bothrops alternatus venom. Arch Toxicol (2025). https://doi.org/10.1007/s00204-025-04188-9