The fat mass and obesity-associated gene (FTO) has previously been associated with human body mass index and porcine intramuscular fat content. In this study, the potential alternative splicing pattern of the FTO gene was investigated, and three novel splice variants were identified in Large White and indigenous Chinese Tibetan pigs. To explore the molecular effect of the FTO gene on the fat deposition caused by castration, 40 paired full-sibling male pigs were divided into intact and castrated groups, and the trait data showed that abdominal fat weight, percentage of abdominal fat weight, and backfat thickness in the intact group were significantly lower than in the castrated group (p < 0.05). FTO mRNA expression in the hypothalamus was significantly increased in the castrated group compared with the intact group (p < 0.05), but was not different in the abdominal fat or backfat tissues. Moreover, the relative expression of the FTO gene was shown to have a higher level in the hypothalamus when compared with expression in the fat tissues (p < 0.05). Our results suggest that there are different patterns of alternative splicing and FTO expression among pig breeds. This study will provide clues for obtaining a better understanding of the porcine FTO gene function.
The purpose of this study was to investigate the effects of castration and slaughter age on amino acid and fatty acid compositions in Longissimus dorsi (LD) muscle of pigs, as well as growth rates and meat quality. The total amino acid, essential amino acid and nonessential amino acid contents of barrows were significantly higher (P<0.01, < 0.001, < 0.001, respectively) than the ones of boars. Additionally, the content of several saturated fatty acids and total mono-unsaturated fatty acids was significantly higher (P<0.001), and total polyunsaturated fatty acids was significantly lower (P<0.001) in the LD muscle of barrows than in boars. Compared with boars, barrows had lower (P<0.05) growth rates after 147 days, higher (P<0.05) intramuscular fat content at 147 days, and higher (P<0.01) average back fat thicknesses at 147 and 210 days. These results suggest that the amino acid and fatty acid compositions of LD muscle from male pigs, as well as growth rates and meat quality, were influenced by castration, and, to a lesser degree, by slaughter age
Castration of male pig produces significant negative effects on skeletal muscle development. The androgen receptor (AR), two splice variants of insulin-like growth factor-I (IGF-I Ea and MGF) and the myostatin gene may play important roles in this process. In the present study, the expression of AR, IGF-I Ea, MGF and myostatin genes in three skeletal muscles, the brachialis, longissimus and semitendinosus, were studied using real-time quantitative RT-PCR. Our experimental design used 14 pairs of male Landrace sire×Yorkshire dam piglets. The two piglets in each pair were full sibs, one of which was castrated at 21 d of age; the other remained intact. The study group was divided into subgroups of equal size. Animals in the first subgroup were slaughtered at 147 d and those of the second at 210 d of age. Carcass weight and lean meat yield were similar between boars and barrows at 147 d of age (p> 0.05), whereas barrows had lower carcass weight and less lean meat yield at 210 d of age (p<0.05). Castration caused down-regulation of AR gene expression at both 147 and 210 d of age (p<0.05). The two splice variants of the IGF-I gene from porcine skeletal muscle were cloned using RT-PCR, and it was found that MGF differs from IGF-I Ea in having a 52-base insert in the last coding exon of the mRNA. Both splice variants were down-regulated by castration only at 210 d of age (p<0.05). No differences in expression of the myostatin gene were observed between boars and barrows at either 147 or 210 d of age (p>0.05). These results suggest that the downregulation of AR, IGF-I Ea and MGF gene expression following castration helps to explain the negative effect of castration on skeletal muscle development.
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