title: Complementary DNA cloning of rat spetex-1, a spermatid-expressing gene-1, encoding a 63 kDa cytoplasmic protein of elongate spermatids.
abstract: We used differential display in combination with complementary DNA (cDNA) cloning approach to isolate a novel rat gene designated as spetex-1, which had an open reading frame of 1,668-length nucleotides encoding a protein of 556 amino acids. Spetex-1 mRNA was highly expressed in testis, and weekly expressed in lung, intestine, and spleen. Spetex-1 expression in the rat testes was detected first at 3 weeks in postnatal development and continued to be detected up to adulthood. A search in the databases showed that the amino acid sequence of spetex-1 was 82% identical to that of its mouse homologue found in the databases. Both rat spetex-1 and the mouse homologue contained Ser-X (X = His, Arg, or Asn) repeats in the middle portion of the proteins. In situ hybridization revealed that spetex-1 mRNA was expressed in haploid spermatids of step 7-18 within the seminiferous epithelium. Immunohistochemical analysis with confocal laser-scanning microscopy demonstrated that spetex-1 protein was not expressed in spermatogonia, spermatocytes, and round spermatids in adult rat testis, but was specifically detected in the residual cytoplasm of elongate spermatids of step 15-18 as well as in residual bodies engulfed by Sertoli cells. We interpreted these data as a potential role of spetex-1 in spermatogenesis, especially in cell differentiation from late elongate spermatids to mature spermatozoa.
authors.affiliation: Laboratory of Zoology, Graduate School of Agriculture, Kyushu University, Higashiku Hakozaki, Fukuoka, Japan. iidahiro@agr.kyushu-u.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iida
authors.forename: Junko
authors.initials: J
authors.lastname: Ichinose
authors.forename: Takane
authors.initials: T
authors.lastname: Kaneko
authors.forename: Takayuki
authors.initials: T
authors.lastname: Mōri
authors.forename: Yosaburo
authors.initials: Y
authors.lastname: Shibata
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D006801:Humans; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013087:Spermatids / Q000166:cytology* / Q000502:physiology; D013091:Spermatogenesis / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D011506:Proteins; D012333:RNA, Messenger; C499424:Spata18 protein, rat