Harvestmen (Arachnida: Opiliones) as Overlooked Predators of Anurans in the Neotropics

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  Harvestmen (Arachnida: Opiliones) as Overlooked Predators of Anurans in the Neotropics ABSTRACT Arthropods are traditionally viewed as invertebrate prey and as predators of other invertebrates, whereas vertebrates are typically considered their predators. However, this paradigm has increasingly been challenged, particularly among arachnids. While several invertebrates are well documented as frog predators, the capacity of particular groups, such as harvestmen (Opiliones), to prey on vertebrates has remained largely anecdotal. Here we report novel field observations of anuran predation by multiple Cranaidae harvestman species across several Neotropical localities. These records include the active capture and consumption of live frogs, demonstrating their role as opportunistic mesopredators. Our findings expand current knowledge of Opiliones ecology by confirming that vertebrate predation occurs across multiple species and localities. Our results suggest that vertebrate consumption...

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