The genus Tityus C. L. Koch, 1836 (Buthidae) includes some of the most dangerous species in South America and Tityus trivittatus Kraepelin, 1898 is one of the most medically important species, causing deaths and serious morbidity especially in Argentina.
Urban populations of Tityus trivittatus have also caused severe cases in children in Paraguay, Adolfo Borges and co-workers have published a genetic and toxinological study of the populations of T. trivittatus in Paraguay.
Their study confirms the medical important of this scorpion in Paraguay. In addition, the study show a significant difference in the venom composition between the populations from Paraguay and Argentina. This result is probably an evidence that the two populations represent different species. Futher studies are necessary to reveal the taxonomical implications of these findings.
Abstract:
Envenoming by scorpions in genus Tityus is a public health problem in Tropical America. One of the most medically significant species is Tityus trivittatus, which is known to occur from southwest Brazil to central-northern and eastern Argentina. In this work, we studied the lethality, composition, antigenicity, and enzymatic activity of venom from a T. trivittatus population found further north in urban areas of eastern Paraguay, where it has caused serious envenomation of children. Our results indicate that the population is of medical importance as it produces a potently toxic venom with an LD50 around 1.19 mg/kg. Venom neutralization in preliminary mouse bioassays was complete when using Brazilian anti-T. serrulatus antivenom but only partial when using Argentinean anti-T. trivittatus antivenom. Venom competitive solid-phase enzyme immunoassays and immunoblotting from Argentinean and Paraguayan T. trivittatus populations indicated that antigenic differences exist across the species range. SDS-PAGE showed variations in type and relative amounts of venom proteins between T. trivitattus samples from Argentina and Paraguay. MALDI-TOF mass spectrometry indicated that while some sodium channel toxins are shared, including β-toxin Tt1g, others are population-specific. Proteolytic activity by zymography and peptide identification through nESI-MS/MS also point out that population-specific proteases may exist in T. trivitattus, which are postulated to be involved in the envenoming process. A timecalibrated molecular phylogeny of mitochondrial COI sequences revealed a significant (8.14%) genetic differentiation between the Argentinean and Paraguayan populations, which appeared to have diverged between the mid Miocene and early Pliocene. Altogether, toxinological and genetic evidence indicate that T. trivitattus populations from Paraguay and Argentina correspond to distinct, unique cryptic species, and suggest that further venom and taxonomic diversity exists in synanthropic southern South American Tityus than previously thought.
Reference:
Borges A, Rojas de Arias A, de Almeida Lima S, Lomonte B, Díaz C, Chávez-Olórtegui C, et al. Genetic and toxinological divergence among populations of Tityus trivittatus Kraepelin, 1898 (Scorpiones: Buthidae) inhabiting Paraguay and Argentina. PLoS Negl Trop Dis. 2020;14(12):e0008899. [Open Access]
Thanks to Adolfo for sending me their article!
No comments:
Post a Comment