Showing papers in "Journal of Heredity in 1974"

Single-Locus Control of Saccharin Preference in Mice

Abstract: VIDENCE for single-locus control of behavioral differences among inbred strains of mice is accumulating; examples include proneness to audiogenic seizure ' , avoidance learning', various activity measures", and vocalization' ' beginning with .096 percent W/V) and doubling succes- sively to 3.08 percent (W/V)). No differences were found between strains B and D in acuity threshold or aversion threshold. The B mice had a lower threshold for preference and drank more from the higher concentrations when the six solutions were simul- taneously presented. The F, hybrids responded like the B mice. The preference and avoidance thresholds are shown in Figure 1. Note that in comparison with the two other genotypes the area of preference for the D mice is restricted both with respect to range of concentrations (horizontal dimension) and to intensity of preference when it occurs (vertical dimension). This pattern sug- gests the complete dominance of the B strain's prefer- ence for saccharin. The hypothesis was further sup- ported by the response to saccharin of both strains and their hybrid during food deprivation s . Pelz et al. 9 also found large differences between inbred strains and feral mice in their preference for saccharin, and although they reported no data from crosses beyond the F,, their results are compatible with the hypothesis of single-locus regulation of preference for saccharin at moderate concentrations. This paper discusses the results of an experiment in which the genetics of preference were investigated in hybrids between B and D mice. Method

Testicular Function in Mouse Strains with Different Age of Sexual Maturation

Abstract: IN house mice (Mus musculus) testicular development is in progress at birth. Even though the duration of spermatogenesis is 34.5 days, all stages of development and differentiation of germinal cells are present after 36 days of age. Androgen levels in the plasma reach a maximum at approximately 55 days of age and most 60-day-old males are fertile. Concentration of free cholesterol in the testes changes little between the ages of 5 and 120 days. However, concentration of esterified cholesterol, which is utilized for steroidogenesis, increases rapidly before puberty. In mice from a random-bred stock concentration of esterified cholesterol in the testes was maximal between 31 and 44 days of age. In the present study, spermatogenesis, testis cholesterol, and plasma testosterone levels were examined at 40, 50, and 60 days of age in mice of four inbred strains produced by selection for early and late sexual maturation of males. The concentration of follicle-stimulating hormone (FSH) in the plasma of these animals at 60 days of age, as well as testis cholesterol levels in Ft hybrids, were also examined. A preliminary account of this work has been published.

Influence of Combinations of Sexes of Children on Family Size

Abstract: In order to study the effect of combinations of sexes of children on family size 4 groups were studied during 1970-1973. The groups were: 1) black college students; 2) Appalachian college students; 3) Vanderbilt college students; and 4) mostly black Job Corps trainees. There was a statistically significant relationship (P < .01) in the Vanderbilt group between 2-children families when the 2 children were of different sexes. Among the Appalachian and black groups the relationship between limited families and children of different sexes did not show up until families had 3 children. Combinations of sexes of children had no effect of limiting family size among the Job Corps group.

T-Alleles in the Mouse Are Probably Not Inversions

Abstract: Animals heterozygous for the t/sup 6/ allele are known to exhibit reduced crossing over in the region near the allele. Testes of t/sup 6//+ males, however, showed first meiotic anaphase bridge frequencies that were not significantly different from those frequencies in T/+ or +/+ animals, nor from frequencies observed in other animals with normal chromosomal arrangements. Two other possible characteristics of inversions, frequencies of broken bridges at anaphase I and frequencies of fragments appearing alone at anaphase I, also were not significantly different between the genotypes. These data indicate that an inversion involving most of the region between T and H-2 is not a likely explanation for the suppression of crossing-over in that region attributable to the t/sup 6/ allele. (auth)