The distribution, spatial clustering, and density of trapdoor spiders in two California coastal dune ecosystems

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  The distribution, spatial clustering, and density of trapdoor spiders in two California coastal dune ecosystems Abstract Coastal dune ecosystems support endemic trapdoor spiders, yet population data for these species are limited. We conducted the first coastal dune trapdoor spider population estimation surveys at Moss Landing State Beach (California) and for Aptostichus stephencolberti Bond 2008 at Sunset State Beach using randomly selected 1m 2 quadrats across ~26,000 m 2 per site. Burrow densities were similar between sites (Sunset: 0.287 burrows/m 2 ; Moss: 0.453 burrows/m 2 ), yielding estimated population sizes of ~35,206 and ~30,959 individuals, respectively. However, spatial analyses revealed contrasting patterns of burrow distribution. At Sunset State Beach, burrow presence was strongly associated with vegetation and occurred closer to plants, despite vegetation being randomly distributed. In contrast, no vegetation–burrow association was detected at Moss Landing, alth...

Electrophysiological modulation of cholinergic neurotransmission by biologically active peptides from Bothrops bilineatus (Viperidae: Crotalinae) venom

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Electrophysiological modulation of cholinergic neurotransmission by biologically active peptides from Bothrops bilineatus (Viperidae: Crotalinae) venom

Abstract

The venom of Bothrops bilineatus, an Amazonian arboreal viper, induces neurotoxicity in mammalian nerve-muscle preparations that is characterized by initial neuromuscular facilitation followed by irreversible blockade. Up until now, the toxins responsible for the neuromuscular excitatory action of this venom have remained unidentified. In this study, we characterized two presynaptically active peptides from B. bilineatus venom using mass spectrometry and electrophysiological analysis at the neuromuscular junction. Fractionation by size-exclusion chromatography yielded eight fractions, with fraction P8 (15 μg/ml) inducing an increase in the twitch amplitude recorded in the mouse phrenic nerve-diaphragm (PND) preparations. Mass spectrometry identified two tripeptides, P8-1 (pEKW) and P8-2 (pENW), in this fraction. Peptide P8-1 was prominently involved in the neuromuscular facilitation and increased the frequency of miniature end-plate potentials (MEPPs) in a manner comparable to the whole fraction (P8). This study provides the first identification of bioactive tripeptides with presynaptic neuromodulatory effects in a Viperidae venom. These findings enhance our understanding of snake venom neurotoxicity and support the potential use of venom-derived peptides as tools for studying synaptic physiology and as templates for novel neuroactive therapeutics.

Couceiro, F.Y.G.M., Pacagnelli, F.L., Torres-Bonilla, K.A. et al. Electrophysiological modulation of cholinergic neurotransmission by biologically active peptides from Bothrops bilineatus (Viperidae: Crotalinae) venom. Arch Toxicol (2025). https://doi.org/10.1007/s00204-025-04176-z