RESUMO
In general, genetic differences across different breeds of pig lead to variation in mature body size and slaughter age. The Commercial breeds Duroc and Large White and the local Brazilian breed Piau are ostensibly distinct in terms of growth and muscularity, commercial breeds are much leaner while local breeds grow much slower and are fat type pigs. However, the genetic factors that underlie such distinctions remain unclear. We used expressed sequence tags (ESTs) to characterize and compare transcript profiles in the semimembranosus muscle of these pig breeds. Our aim was to identify differences in breed-related gene expression that might influence growth performance and meat quality. We constructed three non-normalized cDNA libraries from semimembranosus muscle, using two samples from each one, of these three breeds; 6902 high-quality ESTs were obtained. Cluster analysis was performed and these sequences were clustered into 3670 unique sequences; 24.7% of the sequences were categorized as contigs and 75.3% of the sequences were singletons. Based on homology searches against the SwissProt protein database, we were able to assign a putative protein identity to only 1050 unique sequences. Among these, 58.5% were full-length protein sequences and 17.2% were pig-specific sequences. Muscle structural and cytoskeletal proteins, such as actin, and myosin, were the most abundant transcripts (16.7%) followed by those related to mitochondrial function (12.9%), and ribosomal proteins (12.4%). Furthermore, ESTs generated in this study provide a rich source for identification of novel genes and for the comparative analysis of gene expression patterns in divergent pig breeds.
Assuntos
Cruzamento/economia , Comércio , Etiquetas de Sequências Expressas/metabolismo , Perfilação da Expressão Gênica , Músculo Esquelético/metabolismo , Sus scrofa/genética , Animais , DNA Complementar/genética , Bases de Dados de Proteínas , Regulação da Expressão Gênica , Biblioteca Gênica , Anotação de Sequência Molecular , Dados de Sequência Molecular , Especificidade de Órgãos/genética , Proteínas/genética , Proteínas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Análise de Sequência de DNARESUMO
The components of the insulin-like growth factor (IGF) system appear to be involved in regulation of ovarian follicular growth and atresia in the pig. We investigated the expression pattern of mRNAs for IGF1 (IGF1), its binding proteins (IGFBP1, IGFBP2, IGFBP3, and IGFBP5), and epidermal growth factor in swine follicle cells and ovarian tissue throughout the estrous cycle using the real-time quantitative PCR technique. The results of gene expression were analyzed using linear regression with gene expression as a dependent variable and days of estrous cycle as an independent variable. Additionally, an analysis was made of the correlation of expression levels with plasma concentration of follicle-stimulating hormone, luteinizing hormone, estradiol-17ß, progesterone, and prolactin. Expression of mRNA of all of these genes was detected in granulosa cells and ovarian tissue. IGFBP3 mRNA showed a quadratic expression pattern (P ≤ 0.001) and was significantly and positively correlated with progesterone (r = 0.81; P ≤ 0.01) but negatively correlated with prolactin (r = -0.596; P ≤ 0.05). Expression of the other genes was unaffected by the stage of the estrous cycle. Real-time quantitative PCR effectively detected all transcripts, including the very low levels of IGFBP1 transcripts, and could be used for studies of follicle dynamics.