A comparative study of tryptophan metabolism in skins and livers of black and albino rats

Gestational retinoic acid exposure in the rat: effects of sex, strain and exposure period

Effects of gestational exposure to all-trans retinoic acid (RA) were assessed in the Long-Evans (hooded) and Sprague-Dawley (albino) rat strains. Two exposure periods were evaluated against vehicle controls. Both involved three consecutive daily per os doses of either 2.5 mg/kg RA on gestational days (GD) 11 through 13 or 10 mg/kg RA on GD 14 through 16. All assessments were conducted on at least one male and one female per litter. Substantial main effects of sex, strain and treatment were obtained, but with few significant interactions. Main effects of strain were found on surface righting, neonatal mortality, litter weight and postnatal day (PND) 35 regional brain weight. Among strain effects, the most interesting was the finding that weights of whole brain, frontal cortex, brainstem and cerebellar vermis were lower in hooded than in albino rats. These strain effects seldom interacted with treatment. Among the treatment effects was the finding that GD 11-13 but not GD 14-16 RA exposure impaired the righting reflex in both strains. Moreover, GD 11-13 exposure reduced weight of the cerebellar vermis more than did GD 14-16 RA exposure, while GD 14-16 RA exposure had greater impact on the weight of the cerebellar hemispheres than did GD 11-13 exposure. Covariate analysis suggested that these effects were independent of reductions in body weight. It is concluded that there are few strain or sex differences in the effects of gestational RA exposure, at least for the rat strains evaluated in this study.

Pleiotropisms associated with alleles of the C locus in the domestic fowl

Pleiotropisms associated with the recessive white (c) and albino (ca) alleles at the C locus of the domestic fowl were investigated. Hatchability of fertile eggs was not significantly different for the colored (C+/c, C+/ca), recessive white (c/ca), and albino (ca/ca) chicks; however, late embryonic mortality was higher in ca/ca embryos P less than or equal to .005). Albinos exhibited shorter down lengths (P less than or equal to .01), higher incidences of subcutaneous hemorrhage and inflammation (P less than or equal to .01) and an increased incidence of yolk sac protrusions (P less than or equal to .01). Suppressed body weights (P less than or equal to .01) were evident at all times, except at hatching, in both male and female albinos reared in batteries. Recessive white females also exhibited smaller body weights than colored chicks at 7 and 8 weeks of age in battery trials (P less than or equal to .01). Significant suppression of body weights occurred in albinos only at 4 weeks of age in trials where floor rearing was used. Mortality in albinos was also significantly higher, particularly under floor rearing conditions (P less than or equal to .01). In addition, both feed consumption and feed utilization were reduced in albinos (P less than or equal to .01). These data suggest that melanin synthesis is an important component in the expression of a number of important physiological traits and that the C locus exerts a previously undefined regulatory influence on such traits.