Changes of fatty acids in phosphatidylcholine on sperm membrane during Macrobrachium rosenbergii sperm transit through spermatic duct and lipid analysis in spermatic vesicles

• Dynamical changes of fatty acids (FA) within a single species of phospholipid, PC.
• Distribution and quantitation of FA in PC band were comparable between gas chromatography (GC) and imaging mass spectrometry (IMS).
• FA profile was novelly identified in spermatic vesicles which may function in lipid shuffling and modification on sperm membrane.

Sperm maturation taking place in male accessory tracts is a complex series of biomolecular dynamics of both lipids and proteins on sperm plasma membrane. In this study, we compared fatty acid (FA) compositions on a single banded phophatidylcholine (PC) in Macrobrachium rosenbergii sperm collected from testis (Tsp) and vas deferens (Vsp) to give an insight of membrane lipid dynamic during sperm maturation. Saturated (SAT, predominantly C16:0) and monounsaturated fatty acids (MUFA, predominantly C18:1, n9) were apparently higher in Vsp whereas the polyunsaturated fatty acids (PUFA, mainly C20:5, n3 and C22:6, n3) were evidently lower. Higher level of PUFA in the Vsp was also supported by merocyanine staining followed by flow cytometric analysis. Imaging mass spectroscopy (IMS) gave both comparative and quantitative data of the paired FA within an intact PC molecule while it also provided FA distribution within the PC band. The levels of lipids, particularly cholesterol (CHO) and sphingomyelin (SM), as well as PUFA and other FA species in the spermatic vesicles (SV) were found to be opposite to those of Vsp. We thus believe that an alteration of lipid compositions in sperm membrane is partly modulated via SV transport in vas deferens, which is considerable a part of sperm maturation process in M. rosenbergii, similar to that reported for mammalian epididymal sperm maturation.Statement of relevanceThis work will provide an insight of lipid dynamics on sperm plasma membrane which relates to a part of sperm maturation process. Nutritional management with the known fatty acid compositions of mature sperm would help to improve sperm quality for practical aquaculture.