Y-chromosome length in sublines of two mouse strains

The genetics of pheromonally mediated intermale aggression in mice: current status and prospects of the model

A genetic model of pheromonally mediated aggression in laboratory male mice, which has been developed over the past decade, is reviewed and integrated with recent developments in the neurobiology of olfaction and the chemistry of pheromones in Mus musculus. Experimental data strongly support the possibility of enzymatic activation of aggression promoting and inhibiting pheromones by beta-glucuronidase (EC 3.2.1.31). These findings introduce important questions as to the involvement of beta-GLU genes (Gus and Eg on chromosomes 5 and 8, respectively) in the determination of urine odor profiling. The discovery of two neuroanatomically, and functionally distinct, olfactory structures in 1975 led the way for direct selection of olfactory bulb relay neurons, medial amygdala nucleus neurons and TIDA-neurons for analysis of the genetic mechanisms involved in pheromonal action on aggressive and other olfactory mediated social behaviors in rodents.

The Y chromosome, social signals, and offense in mice

Offense is one type of aggression in mice (Mus musculus/Mus domesticus). Offense was measured in a panel of testers design for two congenic strains of mice. The two congenic strains were DBA1Bg and DBA1. C57BL10-YBg. These differ in the Y chromosome. Offense was measured for the following dyadic pairs: Group 1 (DBA1 tested against a DBA1 opponent); Group 2 (DBA1 tested against a DBA1.C57BL10-Y opponent); Group 3 (DBA1.C57BL10-Y tested against a DBA1.C57BL10-Y opponent); and Group 4 (DBA1.C57BL10-Y tested against a DBA1 opponent). Group 1 was more aggressive than Group 3, whereas Group 2 was no more aggressive than Group 4. Thus, when the experimental and opponent pairs have the same Y chromosome, the congenics differ in offense, whereas when the experimental and opponent pairs have different Y chromosomes, the congenics do not differ in offense. These findings are consistent with the hypothesis that these Y chromosomes affect the display of and response to social or other stimuli for offense of mice. These stimuli may be individual recognition chemosignals in urine.

Differential effect of the DBA1 and C57BL10 Y chromosomes on the response to social or other stimuli for offense

Offense was measured in a homogeneous set test and a standard opponent test for two congenic strains of mice. The two congenic strains were DBA1Bg and DBA1.C57BL10Y-Bg, which differ in the Y chromosome. DBA1 males were more aggressive than DBA.C57BL10-Y meles in the homogeneous set test, whereas DBA1.C57BL10-Y males were more aggressive than DBA1 males in the standard opponent test. These findings are consistent with the hypothesis that this Y-chromosomal variant affects an individual's response to social or other stimuli for offense rather than its display of social or other stimuli for offense or its fighting propensity per se. It may be that this is a differential response to urinary chemo-signals.