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Intermale aggression tested in two procedures, using four inbred strains of mice and their reciprocal congenics: Y
P V Guillot1, M Carlier, S C Maxson
1URA 1294 CNRS, Université Paris V-René Descartes, UFR Biomédicale, France.
Abstract:
Indications of a role for the nonpseudoautosomal region of the Y chromosome (YNPAR) in intermale attack behavior have been demonstrated by Maxson's group using C57BL/10 (B10) and DBA/1 (D1) inbred mouse strains and their reciprocal congenics. Carlier and Roubertoux' group, using CBA/H (H) and NZB/B1NJ (N) mice, did not find such a YNPAR effect. For the two research groups, however, not only were the parental strains different, but also the rearing conditions and testing methods. The divergent conclusions drawn may therefore have been due either to genetic variation or to environment-related variables. We carried out two experiments to investigate these alternatives. The N and H strains were raised and tested according to the experimental design used by Maxson's group (homogeneous set test) and the D1 and B10 strains were raised and tested according to the experimental design of Carlier and Roubertoux' group (standard opponent test). Considering all studies together, the YNPAR effect appeared in both sets of mice only when using the homogeneous set test. This raises the question of what environmentally related variables are involved in the YNPAR effect on intermale attack. One strong hypothesis is that the different types of opponents in each experimental design send differing olfactory signals, which, in turn, differentially affect the capacity to elicit intermale attack behavior.
Insights
The nonpseudoautosomal region of the Y chromosome (YNPAR) influences male mouse aggression, but this effect is dependent on the testing environment. Specifically, the homogeneous set test revealed YNPAR
Area of Science:
- Behavioral Neuroscience
- Genetics
- Animal Behavior
Background:
- Previous studies on the Y chromosome's nonpseudoautosomal region (YNPAR) and male aggression yielded conflicting results.
- Discrepancies were attributed to variations in mouse strains, rearing conditions, and testing methodologies.
Purpose of the Study:
- To investigate whether genetic or environmental factors explain the divergent findings regarding the YNPAR's role in intermale aggression.
- To determine the influence of experimental design on the YNPAR's effect.
Main Methods:
- Two experiments were conducted using different mouse strains (C57BL/10, DBA/1, CBA/H, NZB/B1NJ).
- Mice were tested using either the homogeneous set test (Maxson's design) or the standard opponent test (Carlier and Roubertoux's design).
- Experimental designs were crossed with mouse strains to isolate variables.
Main Results:
- The YNPAR effect on intermale attack was observed in both mouse strain sets exclusively when the homogeneous set test was employed.
- The standard opponent test did not reveal a significant YNPAR effect, irrespective of the mouse strain used.
- This suggests environmental variables, potentially olfactory cues, mediate the YNPAR's influence.
Conclusions:
- The YNPAR's role in intermale aggression is contingent upon the experimental testing conditions.
- The homogeneous set test appears to be a critical factor in eliciting the YNPAR effect.
- Olfactory signals from opponents may play a significant role in modulating YNPAR-dependent aggression.