“EFFECT OF THE WATER SOLUBLE FRACTION FROM CRUDE OIL ON THE LIPID METABOLISM OF SHRIMP”

LAVARIAS, SABRINA MARIA LUISA; HERAS, H.; POLLERO, R.J.

Vitoria, Brasil

Congreso; V Reunión SETAC Latinoamérica. ECOTOX; 2002

SETAC

Hydrocarbon pollution produced by human activity is critical in rivers and coastal areas such as La Plata river estuary in Argentina. The region is exposed to hydrocarbons and there is a need to evaluate the ecotoxicological effects on the  species from the local community. Using the autoctonous freshwater shrimp Macrobrachium borellii as a bioassay model, we studied the effect of sublethal concentrations of the water-soluble fraction of petroleum hydrocarbons (WSF) on some key enzymes of lipid metabolism. WSF from light crude oil was prepared by stirring the oil with cold freshwater, and analyzed by GC. Based on the LC50 96h determined for adults (1.56 ppm), both shrimp adults and embryos under active organogenesis were exposed to 0.6 ppm total hydrocarbons for 7 days. Control animals were kept under the same conditions but without WSF. Subcellular fractions (microsomes, cytosol, and mitochondria) from both embryos and adult hepatopancreas were obtained, and the activities of Palmitoyl-CoA ligase (Lg), Triacylglycerol lipase (TAG-Lp) and fatty acid b-oxidizing system (B-ox) were assayed. All enzymatic activities were significantly increased in the WSF-exposed organisms. In hepatopancreas, Lg, TAG-Lp and B-ox were increased by 165, 167 and 38 % compared to the control lots, respectively, while in embryos the observed increases were 36,62 and 154 % compared to non-exposed embryos, respectively. These differences in the response of the shrimp to the WSF indicate an increase of the lipid catabolic and anabolic pathways. The observed increase of the fatty acid b-oxidation and TAG lipase could be useful to cope with the increased energy demands caused by the xenobiotic, and could be employed as a biochemical biomarker.