A male-specific QTL for social interaction behavior in mice mapped with automated pattern detection by a hidden Markov model incorporated into newly developed freeware

•New freeware, called DuoMouse, was designed to study social interaction behavior in mice.•A hidden Markov model was used to estimate the social behavior automatically.•Multiple subconsomic strains were generated to map a locus that controls social behavior.•DuoMouse was used to map a new genetic locus for male-specific social interaction.

BackgroundOwing to their complex nature, social interaction tests normally require the observation of video data by a human researcher, and thus are difficult to use in large-scale studies. We previously established a statistical method, a hidden Markov model (HMM), which enables the differentiation of two social states (“interaction” and “indifference”), and three social states (“sniffing”, “following”, and “indifference”), automatically in silico.New methodHere, we developed freeware called DuoMouse for the rapid evaluation of social interaction behavior. This software incorporates five steps: (1) settings, (2) video recording, (3) tracking from the video data, (4) HMM analysis, and (5) visualization of the results.ResultsUsing DuoMouse, we mapped a genetic locus related to social interaction. We previously reported that a consomic strain, B6-Chr6CMSM, with its chromosome 6 substituted for one from MSM/Ms, showed more social interaction than C57BL/6 (B6). We made four subconsomic strains, C3, C5, C6, and C7, each of which has a shorter segment of chromosome 6 derived from B6-Chr6C, and conducted social interaction tests on these strains. DuoMouse indicated that C6, but not C3, C5, and C7, showed higher interaction, sniffing, and following than B6, specifically in males.Comparison with existing methodThe data obtained by human observation showed high concordance to those from DuoMouse. The results indicated that the MSM-derived chromosomal region present in C6—but not in C3, C5, and C7—associated with increased social behavior.ConclusionsThis method to analyze social interaction will aid primary screening for difference in social behavior in mice.

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