Blair H T, McCutcheon S N, Mackenzie D D, Gluckman P D, Ormsby J E, Brier B H
Genet Res. 1989 Jun;53(3):187-91. doi: 10.1017/s0016672300028159.
A divergent selection experiment with mice, using plasma concentrations of insulin-like growth factor-1 (IGF-1) at 42 days of age as the selection criterion, was undertaken for 7 generations. Lines were not replicated. To obtain sufficient plasma for the IGF-1 assay, blood from four individuals was volumetrically bulked to obtain a litter mean IGF-1 concentration. This necessitated the use of between family selection. Although inbreeding accumulated in a linear fashion in each of the high, control and low lines, the rates were different for each line (3.6, 1.6 and 5.3% per generation for the high, control and low lines, respectively). As a consequence, the effects of selection and inbreeding are confounded in this experiment. Divergence between the high and low lines in plasma concentrations of IGF-1 continued steadily until generation 5. In generations 6 and 7, there was a reduced degree of divergence and this contributed towards the low realized heritability value of 0.15 +/- 0.12. Six-week liveweight showed a steady positive correlated response to selection for or against plasma concentrations of IGF-1 until generation 4 (high-low difference = 1.7 g = 12%). In generation 5, a substantial drop in 6-week liveweight in the low line relative to both the high and control lines occurred (high-low difference, 3.9; g, 25%). This difference was maintained until generation 7.(ABSTRACT TRUNCATED AT 250 WORDS)
以42日龄小鼠的胰岛素样生长因子-1（IGF-1）血浆浓度作为选择标准，进行了一项为期7代的小鼠 divergent 选择实验。品系未进行重复。为了获得足够的血浆用于IGF-1检测，将来自4只个体的血液按体积混合以获得窝均IGF-1浓度。这就需要采用家系间选择。尽管在高、对照和低三个品系中近亲繁殖均呈线性累积，但各品系的速率不同（高、对照和低品系分别为每代3.6%、1.6%和5.3%）。因此，在本实验中选择和近亲繁殖的效应相互混淆。高、低品系之间IGF-1血浆浓度的差异一直稳定持续到第5代。在第6代和第7代，差异程度有所降低，这导致了较低的实际遗传力值0.15±0.12。直到第4代，6周龄体重对IGF-1血浆浓度的正向或负向选择表现出稳定的相关反应（高-低差异 = 1.7 g = 12%）。在第5代，低品系的6周龄体重相对于高品系和对照品系均大幅下降（高-低差异，3.9；g，25%）。这种差异一直维持到第7代。（摘要截断于250字）
