Frontiers in Marine Science (Nov 2015)
Hepatic UDP-glucuronosyltransferase enzyme activity decreased during salt acclimation of sea lamprey juveniles from Minho river basin
Abstract
Sea lamprey (Petromyzon marinus L., 1758) is an anadromous species which migrates twice during its life cycle between freshwater and seawater. During downstream migration, the juveniles are subject to salinity changes ranging between 0 and 35. The aim of this study was to evaluate the influence of salinity in hepatic biomarkers of stress and biotransformation of juveniles from Minho river basin, Portugal, during trophic migration. Sampled juveniles (macrophthalmia) were transported alive to the laboratory and maintained in 200 L tanks with LSS life support system. The specimens were separated in three groups of five pools (#8): i) macrophthalmia, salinity 0 for 7 days; ii) macrophthalmia, salinity 0 for 30 days and, iii) macrophthalmia subjected to a salt gradient up to salinity 35, for 30 days. At final of the experiments the weight and the length of specimens were determined. Microsomes and cytosol obtained by centrifugation of liver homogenates were used for fluorimetric quantification of glutathione (GSH), glutathione disulphide (GSSG) and malondialdehyde (MDA) and, spectrophotometric determination of catalase (CTT1) and UDP-glucuronosyltransferase (UDPGT) activities. Stats include ANOVA I and Duncan test. The results showed that salt exposure of the animals caused a decrease in the body weight and condition factor (K) without changes the hepatic somatic index (p <0.05). It was also observed a decrease in the GSH/GSSG ratio and UDPGT activity, markers of oxidative stress and loss of biotransformation capacity of liver macrophthalmia (p <0.05). This disturbances may jeopardize the success of sea lamprey trophic migration, if occur a permanent or accidental exposure of juveniles to organic pollutants on the path to the sea. In addition, the salt exposure did not change the liver cytosolic MDA content (p <0.05). The significant increase in CTT1 activity may have contributed to prevent hepatic oxidative damages in the sea lamprey juveniles.
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