Pursel V G, Mitchell A D, Bee G, Elsasser T H, McMurtry J P, Wall R J, Coleman M E, Schwartz R J
Biotechnology and Germplasm Laboratory, USDA-ARS, Beltsville, Maryland 20705, USA.
Anim Biotechnol. 2004 May;15(1):33-45. doi: 10.1081/ABIO-120029812.
The goal of this research was to determine whether directing expression of an insulin-like growth factor I (IGF-I) transgene specifically to striated muscle would alter the growth characteristics in swine. Transgenic pigs were produced with a fusion gene composed of avian skeletal alpha-actin regulatory sequences and a cDNA encoding human IGF-I. Six founder transgenic pigs were mated to nontransgenic pigs to produce 11 litters of G1 transgenic and sibling control progeny. Birth weight, weaning weight, and proportion of pig survival did not differ between transgenic and control pigs. The ADG of pigs as they grew incrementally from 20 to 60 kg, 60 to 90 kg, and 90 to 120 kg, respectively, did not significantly differ between transgenic and control pigs. Efficiency of feed utilization (gain:feed) was also similar for transgenic and control pigs. Plasma IGF-I and porcine growth hormone (pGH) concentrations were determined at 60, 90, and 120 kg body weight. Plasma IGF-I concentrations were 19% higher in transgenic gilts than control gilts and 11.1% higher in transgenic boars than control boars (P=0.0005). Plasma IGF-I concentrations for boars were also higher than for gilts (P=0.0001). At 60, 90, and 120 kg body weight each pig was scanned by dual energy X-ray absorptiometry (DXA) to derive comparative estimates of carcass fat, lean, bone content of the live animal. Control pigs had more fat and less lean tissue than transgenic pigs at each of the scanning periods and the difference became more pronounced as the pigs grew heavier (P<0.005 at each weight). Transgenic pigs also had a slightly lower percentage of bone than control pigs (P<0.05 at each weight). While daily rates of lean tissue accretion did not differ for transgenic and control pigs, daily rates of fat accretion were lower in transgenic pigs than in control pigs (P<0.05). Based on these results we conclude that expression of IGF-I in the skeletal muscles gradually altered body composition as pigs became older but did not have a major affect on growth performance.
本研究的目的是确定将胰岛素样生长因子I（IGF-I）转基因的表达特异性地导向横纹肌是否会改变猪的生长特性。用由禽骨骼肌α-肌动蛋白调控序列和编码人IGF-I的cDNA组成的融合基因培育转基因猪。六头转基因猪奠基者与非转基因猪交配，产生了11窝G1代转基因后代和同窝对照后代。转基因猪和对照猪在出生体重、断奶体重和仔猪存活率方面没有差异。在猪从20公斤逐渐生长到60公斤、60公斤到90公斤以及90公斤到120公斤的过程中，转基因猪和对照猪的平均日增重没有显著差异。转基因猪和对照猪的饲料利用效率（增重：饲料）也相似。在体重60公斤、90公斤和120公斤时测定血浆IGF-I和猪生长激素（pGH）浓度。转基因后备母猪的血浆IGF-I浓度比对照后备母猪高19%，转基因公猪比对照公猪高11.1%（P = 0.0005）。公猪的血浆IGF-I浓度也高于后备母猪（P = 0.0001）。在体重60公斤、90公斤和120公斤时，对每头猪进行双能X线吸收法（DXA）扫描，以得出活体动物胴体脂肪、瘦肉和骨骼含量的比较估计值。在每个扫描阶段，对照猪的脂肪比转基因猪多，瘦肉组织比转基因猪少，并且随着猪体重增加，这种差异变得更加明显（每个体重阶段P < 0.005）。转基因猪的骨骼百分比也略低于对照猪（每个体重阶段P < 0.05）。虽然转基因猪和对照猪的瘦肉组织日生长率没有差异，但转基因猪的脂肪日生长率低于对照猪（P < 0.05）。基于这些结果，我们得出结论，随着猪年龄增长，骨骼肌中IGF-I的表达逐渐改变了身体组成，但对生长性能没有重大影响。
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