F.GENETIC STRAINS RESEARCH CENTER
F-c. Mouse Genomics Resource Laboratory - Tsuyoshi Koide Group

RESEARCH ACTIVITIES

(1) Identification of genetic factors responsible for difference in spontaneous home-cage activity between KJR and C57BL/6

Juzoh Umemori and Tsuyoshi Koide

--It has been previously reported that mice move spontaneously in the habituated home-cage according to a light/dark rhythm, and most mice are active during the dark period. This kind of activity is called a spontaneous home-cage activity. In a variety of strains, mice of C57 were relatively hypoactive, in contrast to mice of KJR were especially hyperactive in habituated home-cage. We studied the spontaneous home-cage activity in terms of the ethological components, genetics factors and biological functions.
--For the ethological and genetic studies, F2 progeny (BKF2) were made between C57BL/6J and KJR strains, and analyzed. Ethological studies showed that total home-cage activity (THA) could be divided to two independent components, active time (AT) that indicated temporal elements of spontaneous home-cage activity, and average activity (AA) that indicated quantitative elements. A little correlation between AT and AA suggested that AA and AT are independent measurement and share only a few common genetic factors.
--In order to study the genetic bases responsible for the differences in spontaneous home-cage activity between KJR and C57BL/6J, we conducted quantitative trait loci (QTL) analyses using BKF2 progeny. QTL analyses showed three significant QTLs associated with the spontaneous home-cage activity. These QTLs were designated as hyperlocomotive activity related QTL1 (Hylaq1), Hylaq2 and Hylaq3. (All Hylaq loci controlled THA that was defined by summing up effects of the AT and the AA.) Hylaq1 was located in a middle region on chr2 and mainly controlled activity time. Hylaq2 was located on the distal side of Hylaq1on chr2 and controlled both of AT and AA. Hyaq3 was located near the telomeric region on chr10, and controlled mainly AA.
--It has been reported that dopamine (DA) system in basal ganglia in brain is associated with movement and spontaneous locomotive activity. To search for candidate genes in the above QTL region, and to understand the biological mechanism that is associated with the spontaneous home-cage activity, strain-comparative analyses on the DA system have been conducted with pharmacological and biochemical methods. The results showed that difference in home-cage activity might be associated with neither DA synthesis, release nor uptake in presynapse but with downstream pathway in DA system following activation of DA receptors in dopaminergic neuron. In particular, function of D1 DA pathway that has role of suppressing the spontaneous activity is possibly reduced in KJR.

(2) A systematic analysis of genetic factors associated with the diversity of mouse behavior

Akinori Nishi, Toshihiko Shiroishi¹ and Tsuyoshi Koide (¹Mammalian Genetics Laboratory)

--A great variation of behavioral pattern is observed in a variety of animals, such as among individuals, populations and species. A number of studies indicated that the behavioral diversity is greatly influenced by genetic factors. The aim of our study is to identify the genetic factors associated with the diversity of behavioral traits.
--In order to study genetic mechanism associated with the behavioral diversity, we are using mouse strains, C57BL/6 and MSM. C57BL/6 is a widely used laboratory strain. The other strain, MSM, was established from Japanese wild mice after the 20 generations of brother-sister breeding. These two strains are genetically different to a great extent and known to exhibit a behavioral difference in a variety of behavioral tests.
--Recently, consomic strains, in which one of the chromosomes of C57BL/6 was replaced with the corresponding chromosome from MSM, were established for a series of chromosomes. These strains are expected as powerful tools for investigating complex traits, which are influenced by multiple genetic factors. In this project, we applied a systematic test battery on the consomic strains to reveal genetic factors associated with behavioral traits. As a behavioral test battery, the home cage test, novel home-cage test and light/dark box test were applied. In the tests, behavioral traits in a habituated condition were measured by the home cage test, the activity in the novel place and habituation for the novel situation were evaluated by the novel home cage test, and anxiety related place preference behavior was measured by using the light/dark box test.
--As the result of these tests, we found that B6-6CMSM consomic strain, which carries MSM-derived chromosomal segment from D6Mit166 to D6Mit12 on chromosome six, exhibited significantly lower activity in the home cage test and the novel home cage test, and indicated higher anxiety related behavior in the light/dark box test comparing to C57BL/6.

(3) Descriptive and Temporal Analysis of the Open-field Behavior in Wild-derived Mouse Strain

Aki Takahashi, Toshihiko Shiroishi¹ and Tsuyoshi Koide (¹Mammalian Genetics Laboratory)

--The open-field is one of the widely used methods for measuring emotionality. In this test, an animal is simply placed into a novel, brightly lit, arena from which escape is barred. It is known that genetic factors make a large contribution to phenotypic variation in various measures of open-field behavior. Most study have used two major variables, ambulation and defecation, that totaled per test. However, mice actually show more various behaviors such as sniffing, rearing, and grooming in the field, and frequency of those behaviors change with time. In this point of view, detailed analysis of the open-field behavior is important to understand psychological status of mice. We therefore described detail of open-field behavior with 12 ethograms (sniffing, locomotion, stretching, leaning, rearing, grooming, face-washing, digging, gnawing, jumping, pausing, freezing) by counting presence of those behaviors in 5 seconds. We previously examined descriptive and temporal analysis of open-field behavior in genetically diverse mouse strains: ten wild-derived mouse strains (PGN2, BFM/2, HMI, CAST/Ei, NJL, BLG2, CHD, SWN, KJR, MSM), one fancy strain JF1, and one laboratory strain C57BL/6. It was revealed that those strains had a great diversity in the temporal changes of those open-field behaviors.
--To elucidate genetic mechanisms underlying the open-field behavior, we have been performing this descriptive study on consomic mouse strains made by C57BL/6 and MSM. These parental strains exhibited great difference in the open-field behavior, C57BL/6 tended to show locomotion and leaning in the later session but MSM exhibited grooming and freezing. Each consomic mouse strain has same genetic background as C57BL/6 except for one chromosome which is introduced from MSM. By examining a series of strains, we will be able to reveal the chromosomes that are associated with the behavioral difference between C57BL/6 and MSM. A half of those strains have been so far analyzed, and some of the strains exhibited different behavior comparing to the parental strain C57BL/6. One strain carrying chromosome 17 from MSM, B6-17MSM, showed reduced locomotion and rearing, and extended risk assessment behavior, stretching. In order to find genetic locus responsible for this behavioral pattern, we will conduct further genetic analysis using B6-17MSM and C57BL/6 strains.

PUBLICATIONS

Reviews
1. 古瀬民生,小出剛（2004）痛覚感受性の個体差にかかわる遺伝学的解析.オピオイド研究の進歩と展望,155-170.鎮痛薬・オピオイド研究会編 ネオメディカル.
2. 小出 剛（2004）野生由来マウス系統を用いた自発運動性の行動遺伝学的解析.動物心理学研究54, 59-66.

ORAL PRESENTATIONS

高橋阿貴,小出 剛「野生由来マウスの多様性を利用したオープンフィールド行動の遺伝学的解析」第19回哺乳動物遺伝学研究会,筑波,2004年6月
小出剛「マウス移動運動の系統差とその遺伝子基盤解明へのQTLアプローチ」第27回日本神経科学大会,大阪,2004年9月
西 明紀、小出 剛「野生由来マウス系統の行動特性に関する研究―マイクロダイアリシス法を用いた解析への試み―」第15回マイクロダイアリシス研究会、東京、2004年12月
　
POSTER PRESENTATIONS

梅森十三、古瀬民生、城石俊彦、小出剛「ケージ内自発運動性に関わるQTLの連鎖解析」第51回日本実験動物学会総会、長崎、2004年5月
西 明紀、米川博通、城石俊彦、小出剛「コンソミック系統を用いたC57BL/6とMSMの行動差に関する遺伝的解析」第51回日本実験動物学会総会、長崎、2004年5月
古瀬民生、城石俊彦、小出剛「マウス痛覚感受性と辛み感受性に関与するQTL遺伝子座の単離と比較」第51回日本実験動物学会総会、長崎、2004年5月
高橋阿貴、小出剛「野生由来マウス系統群を用いたオープンフィールド行動の系統比較」第62回日本動物心理学会、大阪、2004年8月
西明紀、高橋阿貴、米川博通、城石俊彦、小出剛「マウス系統C57BL/6とMSMの行動特性の差異に関わる遺伝的機構の解明」第27回日本分子生物学会年会、神戸、2004年12月
Nishi, A., Yonekawa, H., Shiroishi, T. and Koide, T. A genetic analysis of behavioral diversity between wild-derived mouse strain, MSM/Ms and C57BL/6
18Th International Mouse Genome Conference, Seattle, October 2004.
Takahashi, A., Yonekawa, H., Moriwaki, K., Shiroishi, T. and Koide, T. Descriptive and Temporal Analysis of the Open-field Behavior in Wild-derived Mouse Strains. 18th International Mouse Genome Conference, Seattle, October 2004.

EDUCATION

1. Dr. T. Koide gave a seminar at Tokyo Institute of Psychiatry, February, 2004 (in Japanese).
2. Dr. T. Koide gave a lecture at Institute of Psychology, University of Tsukuba, October, 2004 (in Japanese).