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...

Interpopulational genetic diversity in the medically important scorpion Tityus obscurus (Scorpiones: Buthidae) from northeastern Brazilian Amazonia

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Interpopulational genetic diversity in the medically important scorpion Tityus obscurus (Scorpiones: Buthidae) from northeastern Brazilian Amazonia

ABSTRACT

Scorpion envenoming is considered a public health problem in Brazil. A recent study described a variation in the clinical outcome of envenoming by Tityus obscurus in two populations separated by 850 km in the northeastern Amazon region. Our aim was to evaluate whether such clinical and toxinological variations are associated with underlying differences in genetic diversity between these two T. obscurus populations. We obtained DNA from five individuals of each population, in the municipalities of Belém and Santarém, located east and west of the state of Pará, Brazil, respectively. Gene regions encoding mitochondrial DNA (mtDNA) markers cytochrome oxidase subunit I (COI) and ribosomal 16S RNA (16S) were amplified and sequenced. Phylogenetic analyses were performed using maximum likelihood (ML) and Bayesian inferences (BA) for both molecular data (COI and 16S). The sampled T. obscurus populations corresponded to two distinct mtDNA lineages (genetic distance COIK2 P = 0.08 to 0.13; 16SK2 P = 0.10 to 0.11) with no shared mutations between groups and well supported by ML and BA inferences. Based on the divergence values found between eastern and western populations (COI, 0.07 to 0.12; 16S, 0.10), our study confirms the genetic heterogeneity of T. obscurus populations within the state of Pará, which correlates with observed venom and clinical differences, and reinforces the need for mapping the distribution of haplotypes throughout the geographic range of T. obscurus, to aid in future epidemiological, toxinological, and evolutionary studies.


PARDAL, P. P. de O., COELHO, J. S., SILVA, J. M. da ., ALMEIDA, B. R. R., CHALKIDIS, H. M., BORGES, A., ISHIKAWA, E. A. Y., DINIZ, C. G., SANTOS-NETO, G. da C., & MELO, M. A. D. de .. (2023). Interpopulational genetic diversity in the medically important scorpion Tityus obscurus (Scorpiones: Buthidae) from northeastern Brazilian Amazonia. Acta Amazonica, 53(3), 215–222. https://doi.org/10.1590/1809-4392202202441