A further new species for the genus Ananteris Thorell, 1891 (Scorpiones: Ananteridae) from a poorly prospected region of Brazilian Amazonia

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  A further new species for the genus Ananteris Thorell, 1891 (Scorpiones: Ananteridae) from a poorly prospected region of Brazilian Amazonia Abstract  A new species of the genus Ananteris Thorell, 1891 is described from the region which today defines the ‘Reserva Biológica do Río Trombetas’ in the state of Pará, Brazil. The collection of the unique specimen, presently study, took place previously to the definition of this reserve, in a joint field trip with a team of the Instituto Brasileiro de Desenvolvimento Florestal (IBDF). Ananteris antoni sp. n. is described based on one female specimen collected in a zone of dense humid forest, under death log. With this new description, the number of Ananteris species known for the scorpion fauna of Brazil is now raised to 33. Lourenço W. R., 2026. – A further new species for the genus Ananteris Thorell, 1891 (Scorpiones: Ananteridae) from a poorly prospected region of Brazilian Amazonia. Faunitaxys, 14(63): 1 – 5.  https://doi.o...

Myotoxin II, a snake venom Lys49 phospholipase A2 homolog, induces activation of the ryanodine receptor in artificial bilayers

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Myotoxin II, a snake venom Lys49 phospholipase A2 homolog, induces activation of the ryanodine receptor in artificial bilayers

Abstract

Envenomation by viperid snakes causes acute muscle tissue injury (myonecrosis). An important group of myotoxic components comprises catalytically-inactive Lys49 phospholipase A2 homologs, which disrupt the integrity of the plasma membrane of skeletal muscle fibers through a mechanism that does not involve phospholipid hydrolysis. However, it remains unknown whether other mechanisms are involved in the cytotoxic action of these myotoxins. In this work, isolated calcium release channels (ryanodine receptor, RyR1) incorporated into an artificial lipid bilayer were used to study the action of the Lys49 phospholipase A2 homolog myotoxin II (Mt-II) from the venom of Bothrops asper. Mt-II induced a dose-dependent activation of the RyR1. The open probability of the channel increased with the dose of the toxin. The maximal conductance of the channel remained unchanged during the toxin treatment. Furthermore, the analysis of the open and closed states showed a slight toxin dependency of the latter. These findings suggest that, in addition to the calcium influx from the extracellular space through the disrupted plasma membrane, Ca2+ release from the internal stores may also occur. However, incubation of C2C12 myotubes in culture with the RyR1 antagonist dantrolene did not reduce the extent of cytotoxicity induced by Mt-II, suggesting that the RyR1-mediated increase in cytosolic Ca2+ does not contribute to the overall myotoxicity of this toxin.
Szentesi, P., Magyar, Z. É., Fernández, J., Csernoch, L., Ruiz-Campos, M., Lomonte, B., Gutiérrez, J. M., & Lopez-Dávila, A. J. (2025). Myotoxin II, a snake venom Lys49 phospholipase A2 homolog, induces activation of the ryanodine receptor in artificial bilayers. Toxicon, 108590. https://doi.org/10.1016/j.toxicon.2025.108590