Characterization of a novel gene, sperm-tail-associated protein (Stap), inmouse post-meiotic testicular germ cells

During mammalian spermatogenesis, many specific molecules show the dynamics of expression and elimination, corresponding with the morphological differ entiation of germ cells. We have isolated a novel cDNA designated F77 from mouse testis by cDNA subtractive hybridization between normal and sterile m ice, using the C57BL/6 congenic strain for the hybrid sterility-3 (Hst-3) a llele from Mus spretus. The full-length F77 mRNA was 3.4 kb and showed sign ificant nonmatching with entries in the databases. F77 was mapped at a prox imal position between D8Mit212 and D8Mit138 on mouse chromosome 8, in which no corresponding genes related to its nucleotide sequence were found. F77 mRNA was not detected in any other organs except the testis of adult fertil e mice. F77 protein was only seen in normal adult testis and epididymis. in contrast to normal C57BL/6 mice, F77 mRNA and protein were not seen in ger m cell-deficient Kit(W)/Kit(Wv) mice. By in situ hybridization, F77 mRNA wa s detected mainly at round spermatids in the sexually mature testis, and im munohistochemical analysis revealed that F77 protein was located at the tai l of elongated spermatids. We are proposing the name, sperm-tail-associated protein (Stap), for the gene encoding F77 cDNA. (C) 2001 Wiley-Liss, Inc.