Molecular cloning and localization of caprine relaxin-like factor (RLF) mRNA within the goat testis

The relaxin-like factor (RLF) is one of the insulin-like molecules, which a lso includes insulin, insulin-like growth factor I and II, placentin, and r elaxin. Employing RT- and RACE-PCR on RNA isolated from goat testicular tis sue, we report the cloning and nucleic acid sequence of goat RLF. The capri ne RLF cDNA coding sequence consisted of 396 base pairs encoding a peptide of 131 amino acids. Caprine RLF showed the highest homology in nucleic acid and amino acid sequence with bovine and sheep RLF, suggesting conservation of the RLF gene among ruminants. Northern blot analysis revealed a single 0.9 kb RLF transcript expressed in the goat testis but not in the epididymi s, liver, or muscle tissue. Only a single goat RLF gene is present in the g oat genome as determined by Southern blot analysis. Employing nonradioactiv e in situ hybridization for goat RLF mRNA and immunohistochemistry for 3 be ta-hydroxysteroid dehydrogenase (3 beta-HSD) and 17 alpha-hydroxylase, we i dentified the Leydig cells as the sole source of RLF mRNA in the goat testi s. Mel. Reprod. Dev. 53:135-141, 1999. (C) 1999 Wiley-Liss, Inc.