Efecto de la maduración meiótica sobre los lípidos de fracciones subcelulares de ovocitos de Bufo arenarum

BRUZZONE A; BUSCHIAZZO J; GILI V; ALONSO TS

Buenos Aires

Congreso; IV Jornadas Multidisciplinarias de la Sociedad Argentina de Biología; 2002

Sociedad Argentina de Biología

Full-grown amphibian ovarian oocytes need meiotic maturation to be successfully fertilized. Progesterone-induced maturation produces significant changes in the lipid amount and composition of B. arenarum whole oocytes. It therefore becomes interesting to analyze the maturation effect on lipids from yolk platelets and mitochondria and to elucidate the possible functional relationships between them. The maturation in oocytes was induced with progesterone. Subcellular fractions were isolated, lipids were extracted, separated by thin-layer chromatography and derivatized by methanolysis. Methyl esters were identified in a gas-liquid chromatograph. Phospholipid phosphorous and proteins were colorimetrically measured. In both subcellular fractions, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI) are the main phospholipids. Total phospholipids decreased mainly due to a PC-level reduction in progesterone-treated oocytes. Sphingomyelin significantly decreases suggesting a hormonal activation of a signal tranduction pathway that involves this phospholipid. In the mitochondrial fraction a net decrease in phosphatidic acid and an increase in phosphatidylserine and PI were observed after maturation. Preliminary results suggest that progesterone treatment does not change the acyl group composition of PC and PE in the mitochondrial fraction