Abstract
On their way to the oocyte, sperm cells are subjected to oxidative stress, which may trigger the oxidation of phospholipids (PL). Applying MALDI-TOF MS, HPTLC and ESI-IT MS, we comparatively analyzed the PL compositions of semen and blood of species differing in their reproductive systems and types of nutrition (bull, boar, stallion, lion and man) with regard to the sensitivity to oxidation as well as the accumulation of harmful lyso-PL (LPL), transient products of lipid oxidation. In addition, the protective capacity of seminal fluid (SF) was also examined. The PL composition of erythrocytes and blood plasma is similar across the species, while pronounced differences exist for sperm and SF. Since the blood function is largely conserved across mammalian species, but the reproductive systems may vary in many aspects, the obtained results suggest that the PL composition is not determined by the type of nutrition, but by the relatedness of species and by functional requirements of cell membranes such as fluidity. Sperm motion and fertilization of oocytes require a rather flexible membrane, which is accomplished by significant moieties of unsaturated fatty acyl residues in sperm lipids of most species, but implies a higher risk of oxidation. Due to a high content of plasmalogens (alkenyl ether lipids), bull sperm are most susceptible to oxidation. Our data indicate that bull sperm possess the most effective protective power in SF. Obviously, a co-evolution of PL composition and protective mechanisms has occurred in semen and is related to the reproductive characteristics. Although the protective capacity in human SF seems well developed, we recorded the most pronounced individual contaminations with LPL in human semen. Probably, massive oxidative challenges related to lifestyle factors interfere with natural conditions.
Highlights
The investigation of mammalian sperm lipids revealed large differences between animal taxa
To compare semen data with the situation in other cell types, we investigated the lipid composition of erythrocytes and blood plasma (BP): it can be expected to be different if the PL composition is primarily related to cellular function
According to the high volumes of boar and stallion seminal fluid (SF), the extracted volumes of SF (Fig 2A and 2B) contained much less PL compared to the other species, which is reflected by the poor spot intensities
Summary
The investigation of mammalian sperm lipids revealed large differences between animal taxa. The occurrence of polyunsaturated fatty acyl (PUFA) residues, namely docosapentaenoic (C22:5) and docosahexaenoic (C22:6) residues, in the sn-2 position of the most prominent PL (glycerophosphorylcholine (GPC) and glycerophosphorylethanolamine (GPE)) is a common characteristic of all mammalian sperm studied so far, the type of the chemical linkage at the sn-1 position is variable. This means that sperm membrane lipids largely differ in their contents of diacyl, alkyl-acyl and alkenyl-acyl PL, which are referred to as ester lipids, ether lipids and plasmalogens as a particular group of ether lipids, respectively [1]. It remains unclear whether differences in the type of nutrition (herbi-, omni-, or carnivores) could provide a possible explanation for the observed PL patterns, or whether molecular and cellular interactions within the respective female reproductive system require particular PL arrangements in sperm membranes and, a particular PL composition
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
