Wayne Poley

Behavior genetic analysis of mouse emotionality. III. The diallel analysis.

A total of 775 pure-strain and F1 mice were obtained from a 6×6 diallel mating plan. Previous factor analysis of 42 measures of emotionality identified 14 behavioral factors, ten of which were interpretable. Haymans analysis of variance and analysis of diallel crosses were applied to each of the factors. In general, the findings indicate that the mode of inheritance for emotionality factors is polygenic and in the direction of complete dominance. However, a major point of this investigation is that the mode of inheritance of highly complex behavior such as emotionality depends on the factor in question. For example, the breakdown of dominance effects by factor was as follows: partial dominance—Motor Discharge, Food Motivation, Tunneling-2, and Activity Level (males); complete dominance—Audiogenic Reactivity, Underwater Swimming (males), and Activity Level (females); overdominance—Acrophobia, Territorial Marking (males). Additional findings include directional dominance for Underwater Swimming and Audiogenic Reactivity, and significant sex differences for eight of the 14 factors.

Behavior genetic analysis of mouse emotionality, ii. Stability of factors across genotypes.

Three emotionally divergent strains of mice (SWR/J, A/HeJ, and SJL/J) were mated to produce three populations: a pure strain population (N = 90), an F1 population (N = 120), and an F2 population (N = 96). All Ss were tested on a battery of measures of emotionality. Each population was factored separately by principal components factoring with varimax and promax rotations. Factorial invariance was assessed quantitatively by congruence coefficients. Eight of the resultant factors were found to be replicable across populations. These were autonomic balance, motor discharge, territorial marking, acrophobia, tunneling-1, tunneling-2, underwater swimming, and audiogenic reactivity. Of the eight factors, motor discharge was most distinct in each population and tunneling-1 was least distinct.

Emotionality related to maternal cannibalism in balb and c57bl mice.

Twenty-four female mice from two inbred strains, BALB and C57BL, were tested for emotional behavior. Half of the animals had successfully raised their first litter to weaning, while the other half had eaten their first litter. Cannibalistic females of both strains were found to be more prone to auditory stress than controls. However, the relationship between emotional defecation and cannibalism was found to interact with strain, suggesting an optimum level of arousal.

Effects of light environment on emotionality and the endocrine system of inbred mice

Abstract Eighty mice from two emotionally divergent inbred strains, C57/Alb and Balb/Alb were reared in either a dark or light environment. At 50 days of age, half the animals in each rearing condition were administered a battery of tasks consisting of 19 measures of emotionality. At 58 days of age all animals were dissected and pituitary, adrenal, spleen, and gonad weight recorded. Factor scores were computed for all animals on six factors of emotionality previously obtained. Strain differences were found on all factors and rearing differences on 2 factors: autonomic balance and motor discharge. Strain and sex affected all organ weights, light rearing affected adrenal, spleen and ovary weight, and emotionality testing affected pituitary and adrenal weight. The results were interpreted that light rearing affects maturation of the hypothalamic-pituitary-adrenal axis and response to stress.

Evidence for a territorial marking factor of mouse emotionality

The interpretation of an invariant factor of mouse emotionality as “territorial marking” was tested. Ninety mice from two emotionally divergent strains, SJL/J and SWR/J, were obtained from the Jackson Laboratory. At 33 days of age, they were placed in separate cages and at 60 days of age they were run through a battery of tests consisting of 19 measures of emotionality. Scores were factor analyzed by alpha factoring, followed by varimax and then promax rotations. Factor scores were computed for all Ss on territorial marking and correlated with scores on nine tests of dominance and aggressiveness. The interpretation of Factor 1, territorial marking, was borne out by the correlations with social measures.

Alcohol-preferring and alcohol-avoiding C57BL mice

Three sublines of the high alcohol preference C57BL strain were compared in twochoice alcohol-water testing. As indicated by other investigators, C57BL/10J and C57BL/6J mice prefer 10% alcohol to water. In contrast. C57BL/6A mice prefer water to alcohol. This subline originated from homozygous Jackson Laboratory stock and was maintained by brother-sister inbreeding. Hence a gene mutation is offered as a probable explanation for this behavioral difference.

Effect of magnesium pemoline on avoidance conditioning and intertrial activity in two strains of inbred mice.

Magnesium pemoline was found to have a differential effect on behavior depending upon genotype. The drug resulted in increased activity and reduced avoidance scores for the fast-conditioning C3H strain of mice, whereas it significantly increased avoidance scores and activity for the slow-conditioning ST/bJ strain. The effect of magnesium pemoline on behavior is discussed in terms of an inverted-U relationship between reactivity and learning.