Biosynthesis of glycerophospholipids and sphingolipids in isolated spermatogenic cells

ORESTI GM; AVELDAÑO MI

Puerto Madryn, Chubut, Argentina

Congreso; XLVI Reunión Nacional de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

In addition to glycerophospholipids (GPL) with 16:0 and 22:5n-6, pachytene spermatocytes and round spermatids were recently shown to be rich in sphingomyelins (SM) and ceramides (Cer) with almost exclusively very long chain polyenes (VLCPUFA). How germ cells biosynthesize these highly unsaturated lipids remains to be established. In this study, the incorporation of [3H]-palmitic acid and [3H]-serine into lipids of each of these cells was compared. Most of the label from [3H]-palmitic acid and serine was incorporated into choline and ethanolamine GPL, respectively. Although in lower proportion than GPL, sphingolipids were also labeled with both precursors. Cer was more actively labeled in spermatocytes than in spermatids, the opposite occurred with SM, and glucosylCer (GlcCer) was the most actively labeled sphingolipid in both cell types. This was confirmed with the fluorescent marker NBD C6-Cer, which was incorporated in both cell types to produce fluorescent SM and GlcCer, in proportions that were consistent with those observed with the radiolabeled precursors: a higher labeling of SM in spermatids than in spermatocytes and an active labeling of GlcCer in both. Taken together, the present results indicate that germ cells are able to perform the de novo synthesis of their own phospholipids, including GPL and sphingolipids, independently of Sertoli cells.