New predatory interaction of Trichonephila clavipes (Araneae: Nephilidae) on Fidicinini (Hemiptera: Cicadidae) in a forest fragment of the Neotropical region

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  New predatory interaction of Trichonephila clavipes (Araneae: Nephilidae) on Fidicinini (Hemiptera: Cicadidae) in a forest fragment of the Neotropical region Abstract Trichonephila clavipes (Araneae: Nephilidae) is an orb web-building spider whose diet is primarily based on flying insects. This note aims to report the first predatory interaction of T. clavipes on a cicada of the genus Fidicina (Hemiptera: Cicadidae) in a fragment of the Atlantic Forest in Brazil. The predation event was observed (ad libitum) in the Benjamin Maranhão Botanical Garden situated in the Mata do Buraquinho Wildlife Refuge, northeastern Brazil. A specimen of Fidicina sp. was found freshly dead and trapped in the web of T. clavipes. The nephilid was observed moving slowly between the ventral and dorsal regions of the Fidicina sp. without weaving a web around the cicadid. Then, T. clavipes was observed perched on the left side of the Fidicina sp., with its pedipalps and chelicerae manipulating the thorax ...

Thermoregulation Effects of Phoneutria nigriventer Isolated Toxins in Rats

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Thermoregulation Effects of Phoneutria nigriventer Isolated Toxins in Rats

Abstract

Body temperature is primarily regulated by the hypothalamus, ensuring proper metabolic function. Envenomation by Phoneutria nigriventer can cause symptoms such as hypothermia, hyperthermia, sweating, and shivering, all related to thermoregulation. This study aims to analyze and identify components of the venom that affect thermoregulation and to evaluate possible mechanisms. Rats were used for thermoregulation analysis, venom fractionation by gel filtration and reverse-phase chromatography (C18), and sequencing by Edman degradation. The venom exhibited hypothermic effects in rats, while its fractions demonstrated both hypothermic (pool II) and hyperthermic (pool III) effects. Further separations of the pools with C18 identified specific peaks responsible for these effects. However, as the peaks were further purified, their effects became less significant. Tests on U87 human glioblastoma cells showed no toxicity. Sequencing of the most active peaks revealed masses similar to those of the Tachykinin and Ctenotoxin families, both known to act on the nervous system. The study concludes that molecules derived from venom can act synergistically or antagonistically. Additionally, toxins that affect thermoregulation are poorly studied and require further characterization. These toxins could potentially serve as sources for the development of new thermoregulatory drugs.

Butkeraitis, C. B., Falla, M. V., & Lebrun, I. (2024). Thermoregulation Effects of Phoneutria nigriventer Isolated Toxins in Rats. Toxins, 16(9), 398. https://doi.org/10.3390/toxins16090398