Increase in Aggressiveness of Male Mice Carrying a Reciprocal Translocation, T(10,13), in the Heterozygous State

The agonistic behavior of inexperienced pairs of agouti male mice was determined by counting the bites received from and delivered to the opponent within 24 h. The first 10 min of agonistic encounters was recorded by videotape to analyze the frequency and duration of 10 behavioral traits. Each pair consisted of two F1 males from the cross of (101/C3H)♂ x NMRI♀, one of which (test male) was derived from a father carrying a reciprocal translocation, T(10,13), in the heterozygous state, while the other (standard opponent) stemmed from a chromosomally normal father of the same origin. Since the offspring of a heterozygous translocation are segregating into chromosomally normal and translocation mice, the test male was either chromosomally normal or a carrier of the translocation in the heterozygous state. Apart from the translocation, all males were of the same genotypic constitution. Comparing the differences between translocation carriers and chromosomally normal mice relative to their standard opponent, significantly more winners than losers were found among the translocation carriers. The differences of 10 behavioral traits between the test male and his opponent revealed significantly more contacts, pursuits, and attacks and significantly fewer defense and flight responses of the test males when this was a carrier of the heterozygous translocation, T(10,13).