Abstract
In rat seminiferous tubules (ST), cells that contain polar and neutral lipids with long-chain polyenoic fatty acids (PUFA) and sphingomyelins (SM) and ceramides (Cer) with very long chain (VLC) PUFA of the n-6 series coexist. In this study, pachytene spermatocytes and round spermatids were isolated to determine how these lipids change during spermatogenesis. As the amount per cell of PUFA-rich glycerophospholipids (GPL) decreased with cell size, the 22:5/20:4 ratio increased with cell differentiation. The elovl2 and elovl5 genes, required for 22:5 formation, were expressed (mRNA) in both cell types. Residual bodies- particles with compacted organelles and materials discarded from late spermatids-concentrated cholesterol, 22:5-rich triacylglycerols, and GPL, including plasmalogens and phosphatidylserine. Species of SM and Cer with nonhydroxylated (n-) VLCPUFA (28:4, 30:5, and 32:5) predominated in pachytene spermatocytes, whereas species with the corresponding 2-hydroxy (2-OH) VLCPUFA prevailed in round spermatids. Thus, a dramatic increase in the 2-OH/n-VLCPUFA ratio in SM and Cer was a hallmark of differentiation. A substantial decrease of 2-OH SM occurred between spermatids and mature spermatozoa and 2-OH SM species were collected in residual bodies "en route" to Sertoli cells. Notably, spermatids and spermatozoa gained a significant amount of ceramides devoid of n-VLCPUFA but having 2-OH VLCPUFA as their main fatty acids.
Highlights
In rat seminiferous tubules (ST), cells that contain polar and neutral lipids with long-chain polyenoic fatty acids (PUFA) and sphingomyelins (SM) and ceramides (Cer) with very long chain (VLC) PUFA of the n-6 series coexist
These lipids belong to spermatogenic cells, as indicated by the facts that i) in the prepubertal rat testis, VLCPUFAcontaining species of SM and Cer are not detected; ii) in Abbreviations: ADG, triglyceride with an ether bond; cholesterol esters (CE), cholesterol ester; Cer, ceramide; CGP, choline glycerophospholipid; DPG, diphosphatidylglycerol; EGP, ethanolamine glycerophospholipid; Elovl, fatty acid elongase; GC, gas chromatography; GPL, glycerophospholipid; LPC, lysophosphatidylcholine; PI, phosphatidylinositol; PL, phospholipid; PS, phosphatidylserine; PtS, pachytene spermatocyte; RB, residual body; RS, round spermatid; SM, sphingomyelin; SPZ, spermatozoa; ST, seminiferous tubule; TAG, triacylglycerol; VLCPUFA, very long-chain polyunsaturated fatty acid
The presented results show that, concomitantly with cell size reduction and increased number associated with spermatogenesis, germ cell differentiation implies a reduction in the amount per cell of membrane phospholipids, with a marked increase in the proportion of 22:5n-6 in GPL and of 2-OH VLCPUFA in SM
Summary
In rat seminiferous tubules (ST), cells that contain polar and neutral lipids with long-chain polyenoic fatty acids (PUFA) and sphingomyelins (SM) and ceramides (Cer) with very long chain (VLC) PUFA of the n-6 series coexist. The sphingomyelin (SM) [5] and ceramide (Cer) [6] of cells located in mammalian seminiferous tubules are rich in very long chain (C24 to C34) polyunsaturated fatty acids (VLCPUFA) of the n-6 or the n-3 series, the main ones being 28:4n-6 and 30:5n-6, followed by 32:5n-6 in the rat These lipids belong to spermatogenic cells, as indicated by the facts that i) in the prepubertal rat testis, VLCPUFAcontaining species of SM and Cer are not detected; ii) in Abbreviations: ADG, triglyceride with an ether bond; CE, cholesterol ester; Cer, ceramide; CGP, choline glycerophospholipid; DPG, diphosphatidylglycerol; EGP, ethanolamine glycerophospholipid; Elovl, fatty acid elongase; GC, gas chromatography; GPL, glycerophospholipid; LPC, lysophosphatidylcholine; PI, phosphatidylinositol; PL, phospholipid; PS, phosphatidylserine; PtS, pachytene spermatocyte; RB, residual body; RS, round spermatid; SM, sphingomyelin; SPZ, spermatozoa; ST, seminiferous tubule; TAG, triacylglycerol; VLCPUFA, very long-chain polyunsaturated fatty acid. Please note that n- and 2-OH are used as prefixes to denote nonhydroxy and 2-hydroxy VLCPUFA, respectively
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
