Quantitative expression of mRNA encoding BMP/SMAD signalling genes in the ovaries of Booroola carrier and non‐carrier GMM sheep

Abstract

The GMM sheep is a carrier of Booroola fecundity (FecB) gene, which produces the twins and triplets in one lambing. The homozygous carrier GMM (FecB^BB ), non-carrier GMM and Malpura (FecB⁺⁺ ) ewes were synchronized by progesterone sponges, and the plasma progesterone concentration was measured by RIA. The results showed that the progesterone concentration did not differ significantly (p > .05) in homozygous carrier GMM (5.74 ± 1.2 ng/ml), non-carrier GMM (5.42 ± 1.4 ng/ml) and non-carrier Malpura ewes (5.67 ± 1.5 ng/ml). Further, quantitative expression of BMP factors/receptors and SMAD signalling genes were analysed in the ovaries of sheep by qRT-PCR. The study showed that the expression of BMP2 was slightly higher (p > .05) in carrier GMM than that of non-carrier GMM, but it was almost similar to Malpura ewes. Expression of BMP4 and BMP7 was significantly higher (p < .001; p < .05) in carrier GMM than that of non-carrier GMM and Malpura ewes. Although BMP6 expression was higher (p > .05) in carrier GMM than that of non-carrier GMM, but lower (p > .05) than the Malpura ewes. Expression of BMP15 (p < .05), GDF5 (p < .01) and GDF9 (p < .05) was significantly higher in carrier GMM than non-carrier GMM ewes. Surprisingly, BMPR1B expression was significantly higher (p < .001) in non-carrier GMM and Malpura than the carrier GMM ewes, while TGFβRI did not differ significantly (p > .05) among both GMM genotypes. On the other hand, expression of BMPR1A (p > .05) and BMPRII (p < .05) was higher in carrier GMM than the non-carrier GMM, but significantly lower (p < .001) than the Malpura ewes. It was interesting to note that the expression of SMAD1 (p > .05), SMAD2 (p < .001), SMAD3 (p < .05), SMAD4 (p < .001), SMAD5 (p < .001) and SMAD8 (p < .001) was lower in the carrier GMM than that of non-carrier GMM ewes. It is concluded that the FecB mutation alters the expression of BMPR1B and SMAD signalling genes in the ovaries of homozygous carrier GMM ewes.