Characterization and Quantitation of mRNA for the Inhibin α-Subunit in the Granulosa Layer of the Domestic Hen

Abstract

The role of inhibin in the regulation of follicular development in nonmammalian vertebrates is not well understood. We have used a porcine cDNA probe for the α-subunit of inhibin to characterize and quantitate the mRNA for the inhibin α-subunit in the granulosa layer of the domestic hen. In Experiment 1, RNA was prepared from the large preovulatory follicles and Northern analysis showed a single main band of hybridization between the porcine inhibin α-subunit probe and hen granulosa mRNA at approximately 1700 bp. Slot blot analysis was used in Experiment 2 to quantitate the mRNA for the inhibin α-subunit in the granulosa layers of the largest (F1) to fourth largest (F4) follicles. A significant dose-response relationship was established for increasing doses of RNA but no difference in amount of mRNA for the inhibin α-subunit was found among these four follicle sizes. Finally, in Experiment 3, inhibin α-subunit mRNA in the granulosa layer of F1-F4 follicles removed 6-8 hr after ovulation was quantitated by slot blot analysis. Similar to Experiment 2, a significant linear dose relationship was established for increasing doses of RNA but no difference in concentration of inhibin α-subunit mRNA among follicles was observed. Our results indicate that the porcine cDNA probe for the α-subunit of inhibin detects chicken mRNA at a size comparable to that reported for mammalian species. In addition, no difference in concentration of mRNA for the inhibin α-subunit was detected among the largest preovulatory follicles.