Hair pigmentation in transgenic mice.

A mouse tyrosinase minigene, mg-Tyrs-J, in which genomic 5' noncoding flanking sequence was fused to a mouse tyrosinase cDNA, was introduced into fertilized eggs of BALB/c albino mice. Six transformed mice that exhibited brown agouti hair with some variations in the intensity of pigmentation were obtained. By crossing the founder mice with BALB/c albino mice, transgenic lines and sublines were established. Each subline expressed a characteristic phenotype with their respective band patterns in Southern blot analysis. This indicates that the character is expressed by transgenes integrated at a single location of the chromosomes. The difference in phenotypes among sublines is probably due to the position effect of the chromatin where the transgene is integrated, although a possibility that modification in the nucleotide sequence of the transgene is responsible for the difference cannot be excluded at present.