Lipidos mitocondriales involucrados en la maduración meiotica de anfibios

GILI V; BRUZZONE A; BUSCHIAZZO J; ALONSO TS

Buenos Aires

Congreso; VII Jornadas Multidisciplinarias de la Sociedad Argentina de Biología; 2005

Sociedad Argentina de Biología

Progesterone induces the resumption of meiosis in amphibian full-grown arrested oocytes through a nongenomic mechanism called meiotic maturation. Growing evidence indicates that lipids are involved in this process. The effect of progesterone-induced maturation on the content and composition of polar and neutral mitochondrial lipids was analyzed in Bufo arenarum full-grown oocytes. Ovarian oocytes, manually obtained, were incubated with progesterone to induce maturation. Mitochondrial fraction was isolated by centrifugation, lipids were extracted, separated by thin-layer chromatography and derivatized by methanolysis. Methyl esters were identified in a gas-liquid chromatograph. Phospholipid phosphorous was colorimetrically measured.  A significant fall in total phospholipids, due to phosphatidylcholine (PC) and sphingomyelin (SM) decreases was observed. With respect to the fatty acid composition, a decrease in PC polyunsaturated fatty acids, mainly in linoleic and arachidonic acids was determined. In phosphatidylethanolamine (PE), arachidonic acid showed a net increase. As a consequence of progesterone stimulation, decreases in linoleic and palmitic acids were observed in diphosphatidylglycerol and SM, respectively. Nervonic acid, a characteristic component of SM, underwent a net decrease. In addition, an increase in total neutral lipid amount and significative changes in their fatty acid composition wereevidenced. Altogether, results suggest an active role of mitochondrial lipids during meiosis reinitiation.Bufo arenarum full-grown oocytes. Ovarian oocytes, manually obtained, were incubated with progesterone to induce maturation. Mitochondrial fraction was isolated by centrifugation, lipids were extracted, separated by thin-layer chromatography and derivatized by methanolysis. Methyl esters were identified in a gas-liquid chromatograph. Phospholipid phosphorous was colorimetrically measured.  A significant fall in total phospholipids, due to phosphatidylcholine (PC) and sphingomyelin (SM) decreases was observed. With respect to the fatty acid composition, a decrease in PC polyunsaturated fatty acids, mainly in linoleic and arachidonic acids was determined. In phosphatidylethanolamine (PE), arachidonic acid showed a net increase. As a consequence of progesterone stimulation, decreases in linoleic and palmitic acids were observed in diphosphatidylglycerol and SM, respectively. Nervonic acid, a characteristic component of SM, underwent a net decrease. In addition, an increase in total neutral lipid amount and significative changes in their fatty acid composition wereevidenced. Altogether, results suggest an active role of mitochondrial lipids during meiosis reinitiation.