No abstract

Fish spend their whole life cycle in water and receive the influence of its physico-chemical and biological components over time. The activities of lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) of aquatic organisms can be altered by pollutants in the water. The aim of this study was to determine whether the activities of LDH and MDH in the gills and liver of Astyanax bimaculatus (lambari do rabo amarelo or Two Spots Astyanax in English), can be used as biomarkers of environmental impact in the Una River (SP) Basin. The lambaris for these studies were collected from three water bodies of this basin designated as p1 (Itaim River), p2 (stream by the road to the Municipality of Remédios) and p3 (lake on the road to the Municipality of Dr. José Luiz Cembranelli). The gills and liver were homogenized and this material was then centrifuged and the supernatant was used for LDH and MDH activity assays using the spectrophotometric method, which determined oxidation rate of NADH. The activities of hepatic LDH and MDH and gill MDH were not statistically different in the lambaris collected at the three sites. In the gill tissue, LDH activity of lambaris from p3 was lower than that from p1.This inhibition of LDH in lambaris from p3, as well as the inferior quality of water there, suggest the occurrence of pollutants in this water. It is concluded that the LDH of lambari gills has potential for use as a biochemical marker of environmental impact in the Una River.

Most of the biochemical and physiological studies of Antarctic fish were directed to understand the molecular adaptation of these ectotherms to low temperatures and limits of their metabolic plasticity associated with thermal stress. The principal objective of this review is to discuss the energy metabolism, of L-arginine, antioxidant defense and the xenobiotics of Antarctic fishes as possible markers of environmental change. With the establishment of the circumpolar current and the physical isolation of the region, Antarctic fishes evolved under stable low temperatures. The elevated endemism, low diversity, and the probable stenothermality motivated a number of studies on Antarctic fishes. The presence of enzymes with physical and chemical properties adapted to low temperatures was evident in various studies and fortified the cold adaptation concept of these organisms. By ratifying the Antarctica Environmental Protection Treaty (Madrid protocol), the member countries committed themselves to monitoring the environment of the region. Though, it is one of the most pristine regions of the planet, increasing human activity in Antarctica has given rise to concerns about pollution from combustion oils, heavy metals and sewage. As the energy sustainability of the tissues requires that the velocity of the ATP generator systems should be in step with the energy demand, changes in the environment would lead to elevation in the energy demand of the organisms, which in turn demanded an adjustment of the ATP synthesis velocity. In these cases the enzymatic upregulation and downregulation have been used as biomarkers of the energy metabolism. Traditionally, the antioxidant defense enzymes and the xenobiotic metabolism of fishes have been used as biomarkers to access the natural or anthropic environmental change. However, these studies must correlate the levels of enzymes with the principal risk factors in the environmental pollution. L-arginine metabolism enzymes have been used as biomarkers of the physiological response in mammals, but there are few studies on Antarctic fishes. The central role of the amino acid L-arginine in the synthesis of nitric oxide, polyamines and as a signal in various physiological processes has drawn the attention of scientists. The tissue distribution and the isoforms distribution, along with its control via upregulation and downregulation of the arginase enzymes, nitric oxide synthase and ornithine decarboxylase in Antarctic fishes are potential biomarkers for environmental change. keywords: Antarctica; fish; biomarkers; metabolism; environment. resUMo respostAs MetAbÓlicAs De peiXes AntÁrticos coMo MArcADores De iMpActo AMbientAl. Boa parte dos estudos bioquímicos e fisiológicos com peixes Antárticos foram conduzidos objetivando entender a adaptação molecular desses organismos ectotérmicos às baixas temperaturas, bem como os limites da sua plasticidade metabólica associada com o estresse termal. O principal objetivo desta revisão