Kaps M, Moura A S, Safranski T J, Lamberson W R
Department of Animal Sciences, University of Missouri, Columbia 65211-5300, USA.
J Anim Sci. 1999 May;77(5):1148-54. doi: 10.2527/1999.7751148x.
The objective of this study was to determine the effects of a metallothionein/bovine GH transgene on duration and rate of growth of lean and fat in mice. Mice were produced by mating hemizygous transgenic males to nontransgenic females. Ten weights and six measurements of total body electrical conductivity to estimate body composition were taken on 147 progeny between birth and 84 d of age. Growth traits for fat-free mass (FFM) and body fat mass (FM) were obtained by fitting FFM and FM to a logistic curve y = A/(1 + exp(k(b - t))), where y is FFM or FM, A is asymptotic mass, k and b are curve parameters, and t is time in days. The function and its first, second, and third derivatives for FFM and FM were used to model growth. A mixed model was used with animal and litter as random effects and trans-genotype, sex, and transgenotype x sex as fixed effects in analyses of growth traits. Estimates of transgeno-type and transgenotype x sex interaction were tested by using their corresponding standard errors. Males had greater response to the transgene than females in final FFM and growth rate during the entire growth period. Transgenic males and females had greater duration of lean growth than nontransgenics. Transgenic males began to accumulate fat later, but they eventually gained more fat than transgenic females.
本研究的目的是确定金属硫蛋白/牛生长激素转基因对小鼠瘦肉和脂肪生长持续时间及速率的影响。通过将半合子转基因雄性小鼠与非转基因雌性小鼠交配来培育小鼠。在147只子代小鼠出生至84日龄期间，测量了10次体重，并进行了6次全身电阻抗测量以估计身体组成。通过将无脂肪质量（FFM）和体脂肪质量（FM）拟合到逻辑曲线y = A/(1 + exp(k(b - t)))来获得FFM和FM的生长性状，其中y为FFM或FM，A为渐近质量，k和b为曲线参数，t为天数。使用FFM和FM的函数及其一阶、二阶和三阶导数来模拟生长。在生长性状分析中，使用混合模型，将动物和窝别作为随机效应，转基因类型、性别以及转基因类型×性别作为固定效应。通过相应的标准误差对转基因类型和转基因类型×性别相互作用的估计值进行检验。在整个生长期间，雄性对转基因的反应在最终FFM和生长速率方面比雌性更大。转基因雄性和雌性的瘦肉生长持续时间比非转基因小鼠更长。转基因雄性开始积累脂肪的时间较晚，但最终比转基因雌性积累了更多的脂肪。
