Biomarcadores de estresse e carcinogênese: um estudo em Chelonia mydas

• Autor(a) principal: Fonseca, Leandro Abreu da
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/4367
• topic: Stress; Green turtle; Conservation; Estresse; Cortisol; Tartaruga verde; Fibropapiloma; Conservação; Zoologia; Marcadores biológicos; Stress (Fisiologia); Bioquímica clínica; Biologia molecular; Tartaruga marinha; 57

The use of biomarkers has been proposed as a sensitive tool to warn of biological and chemical stress due to pollution effects, the main feature, the fact that their assessment and quantification can be used predictively to future changes, which may reflect the high levels of biological organization, population, community or ecosystem . The aim of this study was to identify biomarkers related to stress and the development of fibropapillomas in green turtles (Chelonia mydas). For this, we evaluated the responses caused by stress on plasma levels of glucose, lactate and cortisol in turtles subjected to two distinct processes capture and containment, and also in two different health conditions, with and without fibropapillomatosis. Also tested whether chromosomal defects, viewed through the micronucleus test in erythrocytes, were related to different localities of anthropogenic activities and groups affected or not by fibropapillomatosis individuals. Finally, we tested whether the presence of Chelonid herpesvirus 5 in blood samples occurs with the same frequency in tumor tissues, thus representing an important biomarker for the diagnosis of fibropapillomatosis. Our sample consisted of 5 experimental groups (G1, G2, G3, G4 and G5), totaling 180 animals. The G1 was composed of 34 animals without any sign of fibropapiloma and caught in a federal conservation area in Fernando de Noronha/PE. G2, G3, G4 and G5 groups were formed by animals trapped in an effluent of Steel Company in Vitoria/ES, and G2 was composed of 66 animals without signs of fibropapillomas, G3 was composed of 40 animals with fibropapillomas. The G4 group consists of 20 animals with fibropapillomas and group G5 20 without fibropapillomatosis, and both groups were unique to the molecular analyzes. All animals were captured as juveniles like proposed by Hirth (1997). Of the 180 specimens in our sample, only the turtles G3 (n=40) and G4 (n=20) collected in Vitória/ES, 33.33 % of the total sample had fibropapillomas, in different degrees. We found that the values of plasma levels of cortisol and lactate were more elevated in G1 compared to G2. In contrast, plasma glucose levels were significantly lower in G1 compared to G2. Our data on C. mydas are compatible with the induced stress caused by capture method, stimulating the release of cortisol and consequent increase in the lactate response. Still, when compared changes in levels of cortisol and lactate, caused by the stress of capture or the presence of disease, responses were equivalent to each other. Our data also shows that animals with fibropapillomatosis an increased frequency of micronucleated erythrocytes when compared with healthy subjects, and when the micronucleus test is used to compare different qualities environments, individuals most polluted environments show a higher incidence of micronucleated erythrocytes. In PCR, 100 % of tumors and 60 % of the blood samples of the animals were positive for G4 ChHV 5 and all the animals of the G5 group were negative. This was, we suggest that a quantitative analysis of viral DNA in circulating blood, by real-time PCR, could be the next step to determine whether viremia is really constant in animals affected by fibropapillomatosis.