Structural complexity and prey availability shape spider communities under retention forestry

Posted by
 Abstract Retention forestry is promoted as a conservation-oriented management strategy to sustain forest biodiversity by preserving key structural elements, such as single old trees and deadwood. However, the effectiveness of this approach in conserving the diversity of spiders as generalist predators remains unclear, particularly because the effect of structural elements under retention forestry on spiders may be mediated by its effect on prey availability. We sampled spiders (Araneae) and potential prey (Diptera, Hemiptera, Collembola) in 55 1-hectare plots across mixed temperate forests of the Black Forest, Germany. We used pitfall traps targeting species active on the forest floor. We studied spider abundance, taxonomic diversity, ecological diversity (combined measure of functional and phylogenetic distance) and community composition along gradients of forest structure (canopy cover, proportion of conifers, stand structural complexity, volume of lying deadwood, herb cover and...

Thermoregulation Effects of Phoneutria nigriventer Isolated Toxins in Rats

Posted by

 


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