caa a22 4500 386393591 CHVBK 20180307112128.0 cr unu---uuuuu 161130e198906 xx s 000 0 eng 10.1017/S0016672300028159 doi S0016672300028159 pii (NATIONALLICENCE)cambridge-10.1017/S0016672300028159 Responses to divergent selection for plasma concentrations of insulin-like growth factor-1 in mice [Elektronische Daten] 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. This experiment suggests that genetic variation exists at 6 weeks of age in plasma concentrations of IGF-1 in mice. Furthermore, genetic covariation between plasma IGF-1 concentrations and liveweight at 6 weeks of age is likely to be positive. Further experiments have been initiated to examine these theories. Copyright © Cambridge University Press 1989 Blair H. T. † Corresponding author. McCutcheon S. N. Department of Animal Science, Massey University, Palmerston North, New Zealand Mackenzie D. D. S. Department of Animal Science, Massey University, Palmerston North, New Zealand Gluckman P. D. Department of Paediatrics, University of Auckland Medical School, Auckland, New Zealand Ormsby J. E. Small Animal Production Unit, Massey University, Palmerston North, New Zealand Brier B. H. Department of Paediatrics, University of Auckland Medical School, Auckland, New Zealand Genetical Research Cambridge University Press 53/3(1989-06), 187-192 0016-6723 53:3<187 1989 53 GRH https://doi.org/10.1017/S0016672300028159 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0016672300028159 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Blair H. T. † Corresponding author NATIONALLICENCE 700 1- McCutcheon S. N. Department of Animal Science, Massey University, Palmerston North, New Zealand NATIONALLICENCE 700 1- Mackenzie D. D. S. Department of Animal Science, Massey University, Palmerston North, New Zealand NATIONALLICENCE 700 1- Gluckman P. D. Department of Paediatrics, University of Auckland Medical School, Auckland, New Zealand NATIONALLICENCE 700 1- Ormsby J. E. Small Animal Production Unit, Massey University, Palmerston North, New Zealand NATIONALLICENCE 700 1- Brier B. H. Department of Paediatrics, University of Auckland Medical School, Auckland, New Zealand NATIONALLICENCE 773 0- Genetical Research Cambridge University Press 53/3(1989-06), 187-192 0016-6723 53:3<187 1989 53 GRH CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge