Atividade da malato desidrogenase muscular de Astyanax bimaculatus da bacia hidrográfica do rio Una como biomarcadora de impacto ambiental

Abstract

The enzymatic activity of malate dehydrogenase (MDH) and its isoforms may vary in fishes according their living environment. The aim of this work was to investigate the activity of MDH in the muscle tissue of Astyanax bimaculatus (locally called as lambari do rabo amarelo), collected at three different points (P1, P2 and P3) in the Una River Basin (Taubaté, SP), to evaluate it as a candidate biomarker for environmental change. Cytosolic and mitochondrial isoforms of MDH were extracted from muscles. The results indicated that the total enzyme activity was 1.8 and 2.5 times higher in A. bimaculaus at P2, in comparison to specimens collected at P1 and P3, respectively. Seven MDH isoforms were detected in the muscle tissue (MDH-1 to MDH-7). MDH-1 levels of specimens collected at P3 were 1.9 and 2.4 times higher than those from P1 and P2, respectively. However, the levels of MDH-5, -6 and -7 of P3 specimens were significantly lower than P1 ones. These results are possibly related to water quality, considering that P3 is the most polluted among the three sampling sites. The muscle MDH activity of A. bimaculatus was modulated by the environment. Therefore, it can be concluded that this enzyme could be used as a biomarker of environmental change of the hydrographic basin of a neotropical region, where this species occurs.