Analysis and characterization of the bovine Stearoyl COA Desaturase-1 gene
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Date
1994
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Abstract
The carcass characteristics of Angus, American Wagyu and Japanese Black cattle, which had been fed to the Japanese market endpoint, were analyzed. While some of the Angus steers displayed marbling comparable to the Wagyu breeds, extremely high variability made marbling scores difficult to predict under these feeding conditions. When the beef marbling standard is known in Japanese Black cattle, the percentage of ether extractable fat can be predicted by the following equation: Percentage ether extactable fat = (BMS X 2.3058) + 3.6813 with an r-square value of 0.7619. Histochemical studies indicate that the muscle tissue from Wagyu cattle stains best under slightly less acidic conditions than those used for the North American breeds, possibly due to the greater number of adipocytes surrounding the muscle fibers. Northern analyses demonstrated tissue-specific distributions of the SCD-1 mRNA in bovine adipose, muscle and liver RNA, and a single hybridization band at 4.9 kb. The absence of discernible bovine liver SCD-1 mRNA is consistent with the absence of measurable SCD-1 enzyme in bovine liver. The SCD-1 mRNA and SCD-1 enzyme levels in Wagyu and Angus cattle were compared on a per gram adipose tissue and per cell x 10^5 basis, but were not found to be significantly different. Desaturase activity was significantly correlated to myristate (14:0). Restriction fragment length polymorphisms (RFLPs) from multiple generations of Japanese Black cattle confirm previous investigations that the SCD-1 gene is a single copy gene which is inherited in a Mendelian manner. The rat liver SCD-1 cDNA probe was modified to remove the 3' non-coding region and used to isolate the bovine SCD-1 gene from a commercial bovine cosmid library. The identity of the stearoyl-CoA desaturase-1 gene within the cosmids selected was confirmed by restiction mapping of the inserts and sequencing of selected digests. Selective hybridization of the modified rat liver SCD-1 cDNA probe to enzyme digests of the cosmids allowed a placement of the gene along the bovine inserts. Sequencing of the digests also indicated that this gene is located near to a known bovine repeating element.
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Major food science and technology