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...

Riparian spiders make pyriform silk attachment discs that stick better when wet

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Riparian spiders make pyriform silk attachment discs that stick better when wet

Adhesion in wet conditions presents significant challenges due to the disruptive effects of water on interfacial bonding, spreading, and curing. Many organisms have evolved adhesives that adhere strongly in damp or submerged environments. However, the pyriform silk attachment discs of the western black widow spider lose ∼8x of their adhesive strength when wet. Here, we test the hypothesis that riparian species of spiders have evolved attachment discs that are resistant to water's adverse effects on adhesion. We compare adhesion of attachment discs from three terrestrial, relatively dry habitats to three riparian spider species when discs are loaded under both dry and wet conditions. Failure modes shifted from dragline breakage in dry conditions to adhesive failure in wet conditions across all species, highlighting water's impact on interfacial bonding. However, riparian species attachment discs maintained adhesive force when wet while terrestrial species experienced ∼50% reductions in peak force and work of adhesion in wet conditions. These findings suggest that riparian spider silks have evolved specializations that maintain adhesive performance of pyriform attachment disks in wet environments, offering insights into bioinspired design for water-resistant adhesives.

Bernd F. Steklis, Todd A. Blackledge; Riparian spiders make pyriform silk attachment discs that stick better when wet. J Exp Biol 2025; jeb.250902. doi: https://doi.org/10.1242/jeb.250902