Gills glutathione metabolism allows detecting the segregation of Petromyzon marinus L. populations from the Lima and Vouga river basins of Portugal

Abstract

The Petromyzon marinus L. migration from the fresh water to the sea may trigger metabolic alterations in gills that modify its redox environment and its ability to remove xenobiotics by glutathione S-transferases (GST). Thus, the success of the trophic migration of this anadromous species may depend on functional expression of the gills conjugation enzymes which are modulated by chemicals of environmental circulation, present in their habitat during salinity acclimatization. Thus, the main purpose of this work was to evaluate, in detail, the response in tanks to the 0-35 salinity gradient, by oxidative stress markers and glutathione conjugation enzymes of gills of P. marinus juveniles, caught in the Lima and Vouga basins of Portugal, at the beginning of the trophic migration phase. Sampled juveniles were transported to the laboratory with LSS life-support system and subjected, for 28 days, to a gradual and increasing scale of salinity between 0 and 35. The content of glutathione and malonaldehyde was determined by fluorimetry and the mGST and cGST activities by UV/Vis spectrophotometry. Stats analysis include ANOVA I and Duncan test. The results showed that acclimation to salinity 35 did not affect the mGST and cGST activities of gills of the sea lamprey juveniles of both basins, differing of that detected only at salinity 35 for GSH+GSSG and GSSG contents. The animals of the Lima and Vouga river basins were segregated in terms of mGST and cGST activities, higher in the Vouga juveniles, as well as by glutathione content and GSH/GSSG ratio, higher in the Lima individuals, a condition that suggest the influence of specific environmental factors of each basin on glutathione metabolism.