Free Access
Genet. Sel. Evol.
Volume 36, Number 5, September-October 2004
Page(s) 577 - 591
Genet. Sel. Evol. 36 (2004) 577-591
DOI: 10.1051/gse:2004018

Identification and reciprocal introgression of a QTL affecting body mass in mice

Julian K. Christiansa, Kellie A. Rancea, b, Sara A. Knotta, Pat M. Pignatellia, c, Fiona Olivera and Lutz Büngera, d

a  Institute of Cell, Animal and Population Biology, University of Edinburgh, Ashworth Laboratories, King's Buildings, West Mains Road, Edinburgh, EH9 3JT, UK
b  Aberdeen Centre for Energy Regulation and Obesity (ACERO), Energy Balance and Obesity Division, Rowett Research Institute, Greenburn Road, Bucksburn, Aberdeen, AB21 9SB, UK
c  Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
d  Animal Breeding & Genetics Dept., Animal Biology Division, Scottish Agricultural College, Bush Estate, Penicuik, EH26 0PH, UK

(Received 12 January 2004; accepted 27 April 2004)

Abstract - The aim of this study was to examine the effects of a QTL in different genetic backgrounds. A QTL affecting body mass on chromosome 6 was identified in an F 2 cross between two lines of mice that have been divergently selected for this trait. The effect of the QTL on mass increased between 6 and 10 weeks of age and was not sex-specific. Body composition analysis showed effects on fat-free dry body mass and fat mass. To examine the effect of this QTL in different genetic backgrounds, the high body mass sixth chromosome was introgressed into the low body mass genetic background and vice versa by repeated marker-assisted backcrossing. After three generations of backcrossing, new F 2 populations were established within each of the introgression lines by crossing individuals that were heterozygous across the sixth chromosome. The estimated additive effect of the QTL on 10-week body mass was similar in both genetic backgrounds and in the original F 2 population (i.e., ~0.4 phenotypic standard deviations); no evidence of epistatic interaction with the genetic background was found. The 95% confidence interval for the location of the QTL was refined to a region of approximately 7 cM between D6Mit268 and D6Mit123.

Key words: quantitative trait loci / introgression / epistasis / body mass

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© INRA, EDP Sciences 2004