ABSTRACT
This study investigated the stability of housekeeping genes (glyceraldehyde-3-phosphate dehydrogenase, ß-tubulin, ß-actin, phosphoglycerate kinase (PGK), 18S rRNA, ubiquitin and ribosomal protein 19) and the levels of mRNA for bone morphogenetic protein-2 (BMP-2), -4 (BMP-4), -6 (BMP-6), -7 (BMP-7) and -15 (BMP-15), their receptors (BMPR-IA, -IB and -II) and Similar to Mothers Against Decapentaplegic (SMADs) (-1, -5 and -8) in goat follicles of 0.2, 0.5 and 1.0mm, as well as in secondary follicles before and after culture for 18 days. ß-tubulin and PGK were the most stable housekeeping genes and the levels of mRNA for BMP-2 in follicles of 0.2mm were higher than in follicles of 0.5 and 1.0mm. For BMP-4, -6 and -7, the highest levels of mRNA were found in follicles of 1.0mm. The expression of BMPR-IB was higher in follicles of 0.2mm, whereas the levels of BMPR-II were higher in follicles of 0.5mm. The levels of mRNA for SMAD-5 were higher in follicles of 0.2mm, whereas SMAD-8 had higher levels in 0.5-mm follicles. After culture, follicles showed increased levels of mRNA for BMP-2 and reduced mRNA for BMP-4, BMP-7, BMPR-IA and SMAD-5. In conclusion, ß-tubulin and PGK are the most stable reference genes, and BMPs, their receptors and SMADs have variable levels of mRNA in the follicular size classes analysed.
