RESUMO
Augmenting the meat production is among the primary breeding objective of genetic selection programs in poultry production. However, the knowledge about the expression of genes regulating muscle growth at the molecular level is inadequate. Activin type IIB receptor (ACTRIIB) has been reported to play vital role in the negative regulation of muscle growth by binding to multiple members of transforming growth factor-ß superfamily. The present investigation was carried out to comprehend the trend of ACTRIIB messenger RNA in pectoralis major muscle during embryonic (E5-20) and post embryonic age (days 1, 14, 28, and 42) in both Control Broiler (CB) and Aseel by using Real-time PCR. The expression profile of ACTRIIB gene displayed a similar trend in CB and Aseel, however Aseel showed significantly (P < 0.001) higher transcription throughout the period. The fold change in expression of ACTRIIB in Aseel relative to CB varied from 3.94 to 14.72 folds and 3.28 to 7.14 folds during embryonic and post embryonic age, respectively. ACTRIIB exhibited its peak on E7, E11, and E16 during embryonic age, which coincides with the formation of primary and secondary muscle fibers in both lines. While at the time of post-embryonic age, ACTRIIB showed highest transcription on day 1 and lowest transcription on day 28 in both CB and Aseel. Within each line, the expression of ACTRIIB differed significantly (P < 0.001) between days in the course of embryonic and post-embryonic period. ACTRIIB gene expression had significant (P < 0.05) effect on all carcass traits except neck weight. Our results suggest that Aseel expressed higher levels of ACTRIIB transcript than CB. The study inferred that expression pattern of ACTRIIB was analogous in both CB and Aseel, which might imply that molecular mechanisms underlying muscle development and regulation are comparable in nature.
