Inhibition of Bufo arenarum oocyte maturation induced by cholesterol depletion by methyl-beta-cyclodextrin. Role of low-density caveolae-like membranes.

The invaginated structure of caveolae seems to provide an optimal environment for hormone binding leading to oocyte meiotic maturation. We conducted a quantitative analysis of lipids and proteins of detergent-free low-density membranes isolated from Bufo arenarum oocytes and we modulated cellular cholesterol to further understand how these domains perform their regulatory functions in the amphibian system. Light membranes derive from the plasma membrane as suggested by the enrichment in the activity of 5'nucleotidase.

Effect of meiotic maturation on yolk platelet lipids from Bufo arenarum oocytes.

Progesterone induces the resumption of meiosis in Bufo arenarum full-grown arrested oocytes through a nongenomic mechanism called meiotic maturation. Growing evidence indicates that lipids are involved in the maturation process. They are mainly located in yolk platelets, the principal organelles of amphibian oocytes.

Mitochondrial lipids in Bufo arenarum full-grown oocytes.

Both the content and composition of polar and neutral lipids from the mitochondrial fraction of ovarian full-grown Bufo arenarum oocytes were analysed in the present study. Triacylglycerols (TAG) represent 33% of the total lipids, followed by phosphatidylcholine (PC), free fatty acids (FFA) and phosphatidylethanolamine (PE). Diphosphatidylglycerol (DPG) or cardiolipin, a specific component of the inner mitochondrial membrane, represents about 4% of the total lipid content.

Detailed lipid analysis of yolk platelets of amphibian (Bufo arenarum) oocytes.

Yolk platelets, the principal components of amphibian oocytes, have been generally considered as material reservoirs. Their biochemical composition and function during oogenesis and early development have not been fully elucidated. The aim of this study was to carry out a lipidic characterization of yolk platelets from full-grown Bufo arenarum oocytes.

Lipids during Bufo arenarum oogenesis.

The content and composition of phospholipids and triacylglycerols (TAGs) in Bufo arenarum oocytes in stages III and IV of their oogenesis were studied. The total amount of phospholipids in stage IV oocytes is 0.5-fold higher than in stage III oocytes.

Content and composition of phosphoglycerols and neutral lipids at different developmental stages of the eggs of the codling moth, Cydia pomonella (Lepidoptera: Tortricidae).

Phosphoglycerol, triacylglycerol, diacylglycerol, and free fatty acid content was studied in eggs of the codling moth Cydia pomonella at the white, red ring, and black head developmental stages. The composition of total phosphoglycerols and of the three classes of neutral lipids was also analyzed. The highest total lipid content was found in eggs at the white stage, the amount decreasing during development mainly as a result of a diminution in the quantity of phosphoglycerols, which account for approximately 50% of total content at all stages of egg development.