PORCINE STEROIDOGENIC FACTOR-I GENE (PSF-1) EXPRESSION AND ANALYSIS OF EMBRYONIC PIG GONADS DURING SEXUAL-DIFFERENTIATION

The porcine steroidogenic factor-1 gene (pSF-1) was cloned using a com bination of genomic and RT-PCR based cloning methods, pSF-1 consists o f an open reading frame of 1383 nt corresponding to a deduced amino ac id sequence of 461 aa, similar to bovine and human SF-1. Sequence homo logies between pSF-1 and human, bovine and mouse molecules indicate st rong evolutionary conservation at both the nt and aa levels. Northern analysis of pSF-1 expression in adult steroidogenic tissues correlated with porcine steroidogenic acute regulatory protein gene (pStAR) and porcine side chain cleavage (pP450(scc)) gene expression. Notably, pSF -1 expression was readily detected in neonatal testes, absent at 3 wee ks of age, and again readily detected at 3 months and in adult testes, pSF-1 expression was weak but detectable in placental tissues at vari ous times of gestation, and was correlated with pStAR and pP450(scc) e xpression, indicating classical steroidogenesis in this organ. In deve loping gonads from 6-12 weeks of gestation, i.e. during the time of se x differentiation in the pig, Northern analysis demonstrated increasin g expression of pSF-1 in fetal testes and no expression in ovaries. Th is expression pattern was paralleled for pStAR, pP450(scc), and porcin e Mullerian inhibitory substance (pMIS), consistent with pSF-1 involve ment in both steroid and protein hormone secretions of the developing testes during sex differentiation. Porcine SRY HMG-box related gene-9 (pSOX-9) expression also paralleled that of pSF-1 in developing testes . In contrast, DSS-AHC critical region on the X chromosome, gene 1 (pD AX-1) was expressed predominantly in the developing ovaries, indicatin g a possible reciprocal regulation of pSF-1 and pDAX-1 genes in develo ping pig testes and ovaries.