Efeitos da exposição de girinos de rãs-touro, Aquarana catesbeiana (Shaw, 1802) ao material particulado atmosférico sedimentável

Abstract

Air pollution is a major concern today, as it not only affects human health but can also have negative effects on fauna and flora. This type of pollution originates from fuel combustion and industrial production, for example, and can give rise to the so-called atmospheric particulate matter (MPA), popularly known as “black dust”. Given the possibilities of this MPA formation, it is necessary to evaluate the content of this material, as well as the effects it can cause on aquatic organisms. Bullfrog tadpoles, Aquarana catesbeiana, were exposed to sedimentable atmospheric particulate matter, MPA-Se (1g L-1, 96h) for analysis of metal/metalloid and biochemical biomarkers (oxidative stress, neurotoxicity and metabolism). After 96h of exposure, the water in the MPA-Se contained 18 of the 28 metals/metalloids detected in the MPA. Iron (Fe56) and aluminum (Al) showed the highest concentrations, chromium (Cr), manganese (Mn), lead (Pb) and copper (Cu) increased 10- to 20-fold, titanium (Ti), vanadium (V), strontium (Sr), rubidium (Rb), cadmium (Cd), tin (Sn) and nickel (Ni) increased 1- to 3-fold compared to the control. The bioaccumulation of metals/metalloids in the exposure water varied significantly among the organs, with the muscle and liver showing the highest concentrations of metals, followed by the brain. Lipid peroxidation (LPO) and malondialdehyde (MDA) increased only in the muscle, while carbonyl proteins (PC) increased in the liver and brain. Regarding the enzyme nitric oxide synthase (NOS), there was an increase in the liver and brain in the group exposed to MPA-Se. Catalase (CAT) activity decreased in the liver and muscles, while glutathione peroxidase (GPx) activity increased in the liver and kidneys and decreased in muscle. Glutathione S-transferase (GST), responsible for detoxification, increased in the liver and decreased in muscles and kidneys. Cholinesterase (ChE) activity increased only in muscle. The results indicate oxidative stress due to oxidation catalyzed by metals present in MPA-Se. Regarding metabolism, there was an increase in the enzymes pyruvate kinase and phosphofructokinase (PK and PFK) in the liver, while in muscle there was an increase in hexokinase (HK) and a decrease in malate dehydrogenase (MDH), while in the brain there was an increase, the triglyceride metabolite decreased in the liver and brain, increased in muscle. The aminotransferases: alanine aminotransferase (ALT) and aspartate aminotransferase (AST) increased in the muscle, but alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and glucose showed changes only in the brain and the protein showed no significant difference. With these results it is possible to verify a picture of oxidative stress due to the presence of metals, components of MPA. Thus, the results allow demonstrating the deleterious effects of MPA-Se in the aquatic environment, negatively affecting bullfrog tadpoles, by causing oxidative stress induced by the metals incorporated in it. This effect can be evidenced by the responses of the biochemical biomarkers investigated in the different organs.