EFFECT OF A GENE FOR HYPOTRICHOSIS ON THE PERFORMANCE OF MICE IN 2 DIFFERENT ENVIRONMENTS

In two different litters of an inbred strain of laboratory mice in Ber lin (HDA32) arose spontaneously in 1989 a new autosomal recessive muta tion for short hair (sht). Fitness and growth of homozygous shorthair animals (sht/sht) and heterozygous animals of normal appearance (sht/) were compared in normal and warm environment (22 degrees C and 29 de grees C). Altogether 250 matings of homozygous recessive and heterozyg ous parents were carried out The lifelong distinct shorthaired animals were of full fertility and vitality since the age of two weeks. Regar dless of ambient temperature the weights of shorthair animals were sli ghtly reduced However, the maternal effect of the shorthair mother was always positive. For litter size and litter weight at birth, and for survival of liners in the first two weeks significant genotype x envir onment interactions were found: sht/sht dams had at 22 degrees C 5.9+/ -0.29 progeny with 8.1+/-0.35 g litter weight and at 29 degrees C 6.7/-0.25 progeny with 8.7+/-0.30 g litter weight, respectively, and sht/ + dams at 22 degrees C 7.3+/-0.36 progeny with 9.6+/-0.43 g litter wei ght and at 29 degrees C 6.5+/-0.34 progeny with 8.5+/-0.41 g liner wei ght respectively. At 22 degrees C only 76.5 % of the litters of the sh orthair dams mated inter se survived to an age of two weeks, but 92.9 % survived at 29 degrees C. In heterozygous dams 95.2% of the litters survived at 22 degrees C, but only 79.6 % survived at 29 degrees C.