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...

Acoustic stridulating responses of various Tarantula species in Peninsular Malaysia

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Acoustic stridulating responses of various Tarantula species in Peninsular Malaysia

ABSTRACT

Stridulation by stridulatory organs has been linked to tarantulas’ (Araneae: Theraphosidae) defence or sexual communication, and the morphology of such organ has been extensively used in tarantula systematics. This study was conducted to characterise and compare differences in the acoustic pattern of stridulating sound among seven tarantula species for juveniles and adults of both sexes in Peninsular Malaysia. The species were Psednocnemis jeremyhuffi, P. brachyramosa, Selenocosmia sp. ‘Johor’, Omothymus violaceopes, Cyriopagopus robustus, Chilobrachys sp. ‘Kedah’, and Coremiocnemis sp. ‘Kelantan’. Five provocation methods were used to record the sound which was by tapping the substrate/enclosure, blowing air, waving a pen, poking with blunt object and shaking the enclosure. The stridulating behaviour was assessed using a set of parameters. The result showed that the stridulating behaviour differed between species. Dwarf species like P. jeremyhuffi and P. brachyramosa did not make any audible stridulating sound and preferred to remain motionless. Meanwhile, for the other five species only the large adult females stridulated. Adult males of all species did not make any audible sounds, but rather appeared to be more aggressive and frequently bite. Kruskal-Wallis test showed that intensity, pitch frequency, call duration and pulse duration were significantly different between species. Principal component analaysis (PCA) showed the dissimilarity between the adult females from the five species with Omothymus violaceopes and Chilobrachys sp. ‘Kedah’ the most distinct in terms of call patterns. This study provides evidence on the acoustics pattern of stridulating sound for the tarantulas in Peninsular Malaysia.

Nasir, Dzulhelmi & Razak, Irham. (2024). Acoustic stridulating responses of various Tarantula species in Peninsular Malaysia. Sains Malaysiana.  Sains Malaysiana 53(4)(2024): 733-746