The involvement of immunoglobulin superfamily proteins in spermatogenesis and sperm-egg interaction.

The immunoglobulin superfamily (IgSF) proteins are expressed on the plasma membrane between Sertoli cells and germ cells in the testis. IgSF proteins are specifically present at the apical Sertoli-germ cell junction, that is, ectoplasmic specialization and are involved in germ cell differentiation. Some IgSF proteins are present on the surface of germ cells and undergo further biochemical modifications during sperm maturation.

Impairment of spermatogenesis leading to infertility.

Highly differentiated spermatozoa are generated through multiple cellular and molecular processes maintained by Sertoli cells. The cellular events associated with germ cells include proliferation, protein folding and transportation, as well as sequential changes in chromatin and cell organelles. These processes are strictly controlled by the expression of specific genes, including transcription and DNA replication/repair.

Molecular modifications of MC31/CE9, a sperm surface molecule, during sperm capacitation and the acrosome reaction in the rat: is MC31/CE9 required for fertilization?

We examined the modification of the MC31 molecule during capacitation, the acrosome reaction, and studied its role in fertilization. These studies revealed that the molecular mass of MC31 in cauda spermatozoa was approximately 28,000-26,000 Dalton (28-26 kDa). A limited change in molecular mass was seen in capacitated spermatozoa.

Changes in the activity of sperm nitric oxide synthase in the oviductal reservoir during ovulation.

The oviductal isthmus is known to act as a sperm reservoir in several mammalian species including mice, but it is still unclear how sperm are released from the reservoir after ovulation. Recently, nitric oxide (NO) was reported to have important roles as a mediator in various sperm functions, including hyperactivation and capacitation. Therefore, we have investigated the change of the activity of nitric oxide synthase (NOS) of sperm of the isthmus in relation to ovulation under fertilization conditions.