MAPPING OF QUANTITATIVE TRAIT LOCI FOR BODY-WEIGHT ON CHROMOSOME-1 AND CHROMOSOME-4 IN THE RAT

Quantitative trait loci (QTLs) affecting body weight were investigated in the backcross population derived from diabetic BB/OK and spontaneo usly hypertensive rat (SHR). The F1 hybrids were backcrossed onto BB/O K rats, and QTL analysis was performed with the resulting backcross po pulation on chromosomes 1, 3, 4, 10, 13 and 18. According to the strin gent threshold for a lod score of 3.0, markers on chromosomes 1 and 4 were found to be linked with body weight. The QTL with a peak lod scor e (3.3) on chromosome 1 for a male population was located within the r egion flanked by loci Igf2 and D1Mgh12. On chromosome 4, linkage betwe en the body weight and the region around the Npy locus was observed (l ed score 3.1). The existence of the QTL on chromosome 4 affecting body weight was confirmed by congenic BB.LL rats, carrying chromosomal reg ion of SHR (D4Mit6-Npy-Spr) on the genetic background of the BB/OK rat .