RESUMEN
Stingrays skin secretions are largely studied due to the human envenoming medical relevance of the sting puncture that evolves to inflammatory events, including necrosis. Such toxic effects can be correlated to the biochemical composition of the sting mucus, according to the literature. Fish skin plays important biological roles, such as the control of the osmotic pressure gradient, protection against mechanical forces and microorganism infections. The mucus, on the other hand, is a rich and complex fluid, acting on swimming, nutrition and the innate immune system. The elasmobranch's epidermis is a tissue composed mainly by mucus secretory cells, and marine stingrays have already been described to present secretory glands spread throughout the body. Little is known about the biochemical composition of the stingray mucus, but recent studies have corroborated the importance of mucus in the envenomation process. Aiming to assess the mucus composition, a new non-invasive mucus collection method was developed that focused on peptides and proteins, and biological assays were performed to analyze the toxic and immune activities of the Hypanus americanus mucus. Pathophysiological characterization showed the presence of peptidases on the mucus, as well as the induction of edema and leukocyte recruitment in mice. The fractionated mucus improved phagocytosis on macrophages and showed antimicrobial activity against T. rubrumç. neoformans and C. albicans in vitro. The proteomic analyses showed the presence of immune-related proteins like actin, histones, hemoglobin, and ribosomal proteins. This protein pattern is similar to those reported for other fish mucus and stingray venoms. This is the first report depicting the Hypanus stingray mucus composition, highlighting its biochemical composition and importance for the stingray immune system and the possible role on the envenomation process.
RESUMEN
Strandings of oceanic-pelagic elasmobranchs in the southeastern Brazil are reported.Data comes from animals observed in the coast of São Paulo state, between 1999 and 2012. Nine individuals of two species were recorded: Pteroplatytrygon violacea(n = 5; mostly during the winter) and Isurus oxyrinchus(n = 4; two in the winter and two in the summer). For P. violaceathe strandings restricted to the austral winter suggest that the species follows the intrusion of high temperatures water masses recorded in southeastern Brazil during this season, bringing some individuals to shallow waters. For I. oxyrinchus is possible that individuals escaped from hooksof the commercial pelagic longline fishery and suffered injuries inthe esophagus and in the gastric wall, stranding due to difficulties in locomotion and feeding. As these stranded sharks were not necropsied and only two animals were observed during the austral summer, we cannot exclude other causes of beaching such diseases or the intrusion of cold water masses in the continental shelf during this season.(AU)
Encalhes de elasmobrânquios oceânico-pelágicos no sudeste do Brasil são apresentados. Os dados provêm de animais observados no litoral do estado de São Paulo, entre 1999 e 2012. Nove indivíduos de duas espécies foram registrados: Pteroplatytrygon violacea(n = 5; principalmente durante o inverno) e Isurus oxyrinchus(n = 4; dois no inverno e dois no verão). Para P. violaceaos encalhes restritos ao inverno austral sugerem que a espécie segue a intrusão de massas de água quente registradas no sudeste do Brasil durante esta época do ano, trazendo alguns indivíduos para águas rasas. Para I. oxyrinchusé possível que os indivíduos tenham se soltado de anzóis da pesca comercial de espinhel pelágico e sofrido injúrias no esôfago e na parede gástrica, encalhando devido a dificuldades de locomoção e alimentação. Como estes tubarões encalhados não foram necropsiados e apenas dois animais foram observados durante o verão austral, não podemos excluir outras causas de encalhe, como doenças ou a intrusão de massas de águas frias na plataforma continental durante essa temporada.(AU)