IDENTIFICATION AND LOCALIZATION OF COPPER-ZINC SUPEROXIDE-DISMUTASE GENE-EXPRESSION IN RAT TESTICULAR DEVELOPMENT

Reactive oxygen species are highly toxic agents that appear to have an important role in male infertility. In order to understand the potent ial for the testis to be protected from reactive oxygen, the mRNA leve ls of the natural reactive oxygen scavenger, copper-zinc superoxide di smutase (SOD), were determined in testes and other organs in rats usin g northern analysis and in situ hybridization. Northern analysis of to tal RNA from organs of 60-day-old rats demonstrated an SOD mRNA with a transcript length of 0.77 kb; its concentration was highest in the ki dney, liver, testis, and epididymis. In testis, northern analysis of t otal RNA demonstrated two mRNA transcripts of 0.77 kb and 0.94 kb. The concentrations of the 0.77-kb transcript varied only slightly between 10 and 100 days of age. In contrast, the 0.94-kb transcript became de tectable by northern analysis between 30 and 40 days of age, then its concentration rose progressively to peak at 60 days. In situ hybridiza tion studies demonstrated a uniform distribution of SOD mRNA within se miniferous tubules of prepubertal rats at 10 days of age and a heterog eneous, stage-specific pattern in older animals. In mature rats, the h ighest level of SOD mRNA was detected in tubules just prior to spermia tion (stages VI-VIII). In conclusion, two SOD mRNA transcripts were id entified in the rat testes that followed significantly different patte rns of expression during development. in situ hybridization studies re vealed that accumulation of the SOD mRNA in the seminiferous tubule wa s stage specific. These data suggest that SOD may play an important ro le during testicular development and spermatogenesis in rats.