Two new arthropod toxins purified from the venom of the Mexican scorpion Centruroides nigrescens

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  Two new arthropod toxins purified from the venom of the Mexican scorpion Centruroides nigrescens Abstract The venom of the slender black scorpion Centruroides nigrescens , from the State of Guerrero México, was fractionated by Sephadex G–50 gel filtration, followed by carboxymethyl cellulose ion separation and high–performance liquid chromatography, permitting to obtain two new peptides toxic to arthropods. The estimate LD 50 of the soluble venom for the insect Acheta domesticus was 11.1 μg/g body weight, and for the arthropod Armadillidium vulgare was 61.1 μg body weight . The amino acid sequence of toxin Cnige1 (toxic to A. domesticus and A. vulgare ) contains 65 amino acids, with a molecular mass of 7273.37 mass units, whereas toxin Cnige2, toxic to A. domesticus , contains 68 amino acids, with a molecular mass of 7548.81 units. Both peptides are well packed, containing 8 cysteines, which in the native venoms are forming 4 disulfide bridges each. The amino acid sequences f...

Morphometric Analysis of a Trapdoor Spider (Araneae, Idiopidae) across Different Brazilian Biomes Reveals the Geographic Variation of Spiders from the Caatinga Biome

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Morphometric Analysis of a Trapdoor Spider (Araneae, Idiopidae) across Different Brazilian Biomes Reveals the Geographic Variation of Spiders from the Caatinga Biome

Abstract
Widespread species are exposed to different environmental drivers and can consequently present variations in body shape and/or size. Trapdoor spiders of the genus Idiops are generally associated with a sedentary lifestyle and limited dispersion. However, the species Idiops pirassununguensis has a wide distribution, occurring in a diverse range of distinct environmental conditions, with their presence recorded in the Amazon, Caatinga, and Cerrado Brazilian biomes. We investigated how their morphological variation is structured regarding the biomes in which they occur through a morphometric analysis of the linear measurements and morphogeometric shapes of 64 specimens. Combining different methods proved to be a valuable approach to understanding how the spider’s morphology varies in different environments. The results were congruent and complementary, indicating intraspecific geographic variation, with the Caatinga specimens being distinct from their biome conspecifics. In Caatinga, a biome with periods of severe drought and warm climate, I. pirassununguensis specimens were found to be smaller, in addition to having narrower and elongated sternums and shorter legs. The morphological structuring herein is consistent with the results found comparing animals from Caatinga and other Brazilian biomes. Despite differences in their non-sexual structures, the specimens share a set of diagnostic sexual characteristics for the species, allowing all individuals to be classified as belonging to the same species.