Studies on the Mechanism of Genetic Control for Fat Depositon in Cattle

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Genetic and environmental controls of fat deposition are important for beef production. To study the genetic mechanism of fat deposition, molecular genetics and statistical genetics were adopted.With the molecular genetics approach, bovine C/EBP alpha, C/EBP beta, C/EBP delta and PPAR gamma2 genes, that encode transcription factors regulating the adipocyte differentiation, were cloned and sequenced. These genes have the high similarities with the mouse genes. The analysis of bovine C/EBP alpha promoter revealed that C/EBP binding and USF binbing sequences, which were important elements of C/EBP alpha gene regulation in mouse and human, were not conserved in cattle, suggesting different mechanism for regulation of bovine C/EBP alpha gene expression. These features in bovine C/EBP alpha promoter were conserved between Japanese Black and Japanese Brown cattles. Moreover, bovine ob gene was cloned.With the statistical gentetic approach, we investigated how many loci affected the marbling in beef and also whether major gene affected by this trait is present or not. The presence of segregating major gene which has large effect on marbling was expected in Japanese Brown cattle population of Kumamoto Prefecture. Segregating major gene was also detected in some families within that population. Then, this approach is expected as the clue of quantitative trait loci (QTL) analysis with genetic marker.It is revealed from this study that the joint approach with both molecular and statistical genetics is a very powerful tool to elucidate the genetic mechanism of fat deposition.