Lipids with very long chain fatty acids (VLCPUFA) in germ cells and residual bodies

ORESTI GM; REYES JG; LUQUEZ JM; PEDICONI MF; AVELDAÑO MI

Villa Carlos Paz, Córdoba, Argentina

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2008

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

In semminiferous tubules, Sertoli cells and and spermatogonic cells at different stages of differentiation coexist.  In this work, pachytene spermatocytes (PS) and round spermatids (RS) were isolated to study how ceramides (Cer) and sphingomyelin (SM) with VLCPUFA are formed in the testis.  Although the concentration of phospholipids including SM were similar in both cell types, there were many differences in thier polienoic fatty acids (FA).  In glycerophospholipids, the 20:4n-6/22:5n-6 ratio was significantly higher in PS than in RS.  In SM (and Cer) 28:4n-6, 30:5n-6, 32:5n-6 were the main FA in PS, whereas 28:4n-6 predominated in RS.  By contrast, in the latter, an important proportion in SM (and Cer) FA were recovered as a-hydroxylated versions of VLCPUFA (2-OH 28:4 to 32:5).  The residual bodies (RB) contain material -including lipids- that are discarted from late spermatids (elongated forms) as they differentiated to spermatozoa, to be phagocytized and "recycled" in Sertoli cells.  The RB were rich in glycerophospholipids and triacylglycerides with 22:5n-6.  The SM in RB contain virtually no VLCPUFA but was extremely rich in 2-OH VLCPUFA.  The results point to fatty acid desaturase, elongase and hydroxylase activities that are highly specific for long-chain and very long-chain fatty acids encoded by genes that are expressed sequencially as cell differentiation proceeds