Kumar B, Francis S M, Suttie J M, Thompson M P
Department of Biochemistry, University of Otago, Dunedin, New Zealand.
Comp Biochem Physiol B Biochem Mol Biol. 1998 Jul;120(3):543-8. doi: 10.1016/s0305-0491(98)10041-x.
Genetically separate lines of Coopworth sheep have been bred by selecting for (fat genotype) or against (lean genotype) backfat depth. Typically, the total fat content, adjusted for carcass weight, is 21.2 and 29.3% for the lean and fat lines, respectively. As a homologue of the obese gene, which shows altered expression in several forms of obesity, is also expressed in sheep, it was decided to determine whether the obese gene was differentially expressed in each line of sheep. The relative level of expression of obese mRNA was approximately twofold higher in the fat line compared with the lean line in back, omental and perirenal fat depots of ram lambs fed ad libitum or fasted for 48 h. This elevation in the fat line is most likely a secondary consequence of obesity rather than a cause. Fasting for 48 h decreased obese mRNA levels by 8.9-, 8.5-, and 4.2-fold in back, omental and perirenal fat, respectively, in the lean line, and by 8.3-, 5.7-, and 3.5-fold in back, omental and perirenal fat, respectively, in the fat line. The lean and fat lines of sheep, therefore, responded in a similar way to fasting.
通过选择背膘厚度（脂肪基因型）或不选择（瘦肉基因型），培育出了基因分离的库泊沃思绵羊品系。通常，根据胴体重量调整后的总脂肪含量，瘦肉品系和脂肪品系分别为21.2%和29.3%。由于肥胖基因的同源物在绵羊中也有表达，该基因在几种肥胖形式中表达发生改变，因此决定确定肥胖基因在各绵羊品系中是否存在差异表达。在自由采食或禁食48小时的公羊羔的背部、网膜和肾周脂肪库中，脂肪品系中肥胖mRNA的相对表达水平比瘦肉品系高约两倍。脂肪品系中的这种升高很可能是肥胖的继发后果而非原因。在瘦肉品系中，禁食48小时使背部、网膜和肾周脂肪中的肥胖mRNA水平分别降低了8.9倍、8.5倍和4.2倍；在脂肪品系中，背部、网膜和肾周脂肪中的肥胖mRNA水平分别降低了8.3倍、5.7倍和3.5倍。因此，绵羊的瘦肉品系和脂肪品系对禁食的反应方式相似。
