Conversely, the TLR7/8-activated, slow mobility sperm produced embryos and pups that were 81% XX females. Likewise, 83% of the pups obtained following embryo transfer were XY males. Following in vitro fertilization using the ligand-selected high-mobility sperm, 90% of the embryos were XY male. The difference in sperm motility allowed for the separation of Y-sperm from X-sperm. Ligand activation of TLR7/8 selectively suppressed the mobility of the X chromosome–bearing sperm (X-sperm) but not the Y-sperm without altering sperm viability or acrosome formation. Especially, TLR7 was localized to the tail, and TLR8 was localized to the midpiece. In this study, we found that Toll-like receptors 7/8 (TLR7/8) coding the X chromosome were expressed by approximately 50% of the round spermatids in testis and in approximately 50% of the epididymal sperm. By regulating the expression of specific genes, we hypothesized that the X chromosome might exert functional differences in sperm that are usually masked during fertilization. Although overall gene expression is lower in sperm than in somatic cells, transcription is activated selectively in round spermatids.
In mice, the Y chromosome encodes fewer than 700 genes, whereas the X chromosome encodes over 3,000 genes. In most mammals, the male to female sex ratio of offspring is about 50% because half of the sperm contain either the Y chromosome or X chromosome.
0 kommentar(er)
