cell function in spermatogenesis

More than 90 % of the glycolipid in mammalian testis consists of a unique sulfated glyceroglycolipid, seminolipid. The sulfa-tion of the molecule is catalyzed by a Golgi membrane-associ-ated sulfotransferase, cerebroside sulfotransferase (CST). Disruption of the Cst gene in mice results in male infertility due to the arrest of spermatogenesis prior to the metaphase of the first meiosis. However, the issue of which side of the cell function—germ cells or Sertoli cells—is deteriorated in this mutant mouse remains unknown. Our findings show that the defect is in the germ cell side, as evidenced by a transplanta-tion analysis, in which wild-type spermatogonia expressing the green fluorescent protein were injected into the seminifer-ous tubules of CST-null testis. The transplanted GFP-positive cells generated colonies and spermatogenesis proceeded over meiosis in the mutant testis. The findings also clearly show that the seminolipid is expressed on the plasma membranes of spermatogonia, spermatocytes, spermatids, and spermatozoa, as evidenced by the immunostaining of wild-type testes using an anti-sulfogalactolipid antibody, Sulph-1 in comparison with CST-null testes as a negative control, and that semino-lipid appears as early as day 8 of age, when Type B sper-matogonia emerge. Key words: cereboroside sulfotransferase / germ cell trans-plantation / green flourescent protein / knockout mouse / testi