Barietin, a snake venom vascular endothelial growth factor from puff adder Bitis arietans venom, increases the heart rate with minor effect on blood pressure in rats

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  Barietin, a snake venom vascular endothelial growth factor from puff adder Bitis arietans venom, increases the heart rate with minor effect on blood pressure in rats ABSTRACT Snake venom vascular endothelial growth factors (svVEGFs) are homodimeric proteins comprising two equal subunits bound by two intermolecular disulfide bonds. The main biological effects of svVEGFs are local vasodilatation, increasing of vascular permeability, and hypotension. Barietin, a svVEGF purified from the venom of puff adder Bitis arietans , differs from other representatives of this toxin family by its shortened C-terminal amino acid sequence. No data about barietin effects on hemodynamics are available. Studying those in rats we found that barietin at a dose of 1 mg/kg significantly increased heart rate, exerting only a minor influence on blood pressure. In this respect, it differs from other svVEGFs having a significant effect on blood pressure. We aimed to find the barietin active fragment which m...

Abundance, coexistence and behavioural interactions among juveniles of two sympatric tarantulas from Argentina

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Abundance, coexistence and behavioural interactions among juveniles of two sympatric tarantulas from Argentina

Abstract

Grammostola vachoni (Schiapelli & Gerschman, 1961) and Plesiopelma longisternale (Schiapelli & Gerschman, 1942) are two sympatric tarantula species living in mountain systems from central Argentina occurring at the same microhabitat. Adults and juveniles of both species live under rocks, where they construct their shelters. They are also synchronous in egg sac laying and hatching of the first stages (December and January). Given this scenario, it is probable that juveniles compete for resources, such as shelters during early stages. Thus, we evaluated the abundance and demography of both species at their natural habitat, by registering the sizes of individuals found, their refuges, and percentage of coexistence. We also conducted intra- and interspecific interactions to register the behavioural patterns of spiders against congeners and hetero-specific individuals. Grammostola vachoni was more abundant at one site studied; however, both species showed similar abundances at the second site. We identified 16 behavioural units. The most frequent behaviour displayed by both species was “retreat”. The most frequent behaviour during interspecific interactions was “retreat” for P. longisternale, whereas for G. vachoni it was “abdomen elevation”. For intraspecific encounters, the most common behaviours were “contraction” and “silk deposition” for P. longisternale, while for G. vachoni they were “retreat”, “raising palps”, and “grasp”.

Fiorella Signorotto, Micaela Millenpeier, Agustina Aguirre-Morales, Carolina Guerra, Nelson Ferretti "Abundance, coexistence and behavioural interactions among juveniles of two sympatric tarantulas from Argentina," Arachnology, 19(9), 1292-1297, (13 November 2024)