RESUMEN
<p><b>OBJECTIVE</b>To isolate and identify the differentially expressed genes in spermatogenesis for the understanding molecular mechanism of spermatogenesis.</p><p><b>METHODS</b>Screening of the cDNA library, Northern blot, expression and purification in E. coli with GST expression system, immunocytochemical staining of testis sections were used.</p><p><b>RESULTS</b>(1) A cDNA fragment designated as RSD-7 was isolated from rat testis cDNA library. It was 1,238 bp in length, coding a protein of 232 amino acids with the GenBank accession number AF315467. The encoding protein of RSD-7 cDNA had a Ubiquitin-like domain. (2) Northern blot indicated that RSD-7 was uniquely expressed in rat testis, and in the testis RSD-7 emerged on the 30th postnatal day and expressed until 120th postnatal day. (3) Expression and purification of RSD-7 protein in E. coli with GST expression system and were used to obtain anti-RSD-7 antibody. (4) Immunolocalization of RSD-7 in rat testis revealed that it is expressed only in Sertoli cells.</p><p><b>CONCLUSIONS</b>Transcription pattern of RSD-7 and localization of RSD-7 protein in testis have been made, which established the base for the functional study of RSD-7.</p>