CHEMICAL MUTAGENESIS IN MOUSE CIRCADIAN RHYTHMS

小鼠昼夜节律中的化学诱变

基本信息

批准号：
07557187
负责人：
EBIHARA Shizufumi
金额：
$ 1.6万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07557187/
关键词：
circadian rhythm inbred strain mutation genetics chemical mutagenesis QTL wild mice クロラムプシル

项目摘要

Circadian rhythms which are driven by endogenous clocks with a period of approximately 24 hr under constant condition are observed in almost all creatures from procaryotes to mammals. The features of circadian rhythms are common to all species, but molecular mechanisms of circadian rhythms are unclear. The purpose of this study is to isolate circadian mutant in mice to understand molecular mechanisms of circadian rhythms. For this, we have used 3 different strategies. One is chemical mutagenesis, another is isolating a mutant from wild mice population and a third is a screening of inbred strains. Using this strategies, we have found several mutant mice which show abnormal rhythmicity. Furthermore, we have accidentally found another mutation in the course of breeding mice. The mutation found in wild mice population is characterized by loss of circadian rhythms under constant condition and shorter circadian period. Genetic analysis indicated that the arrythmic trait is recessive because … More F1 mice between the mutant and C57BL/6J show normal rhythms and the phenotype segregates in F2 and backcross. In the screening of inbred lines, CS mice were found to have abnormal circadian properties including longer free-running period, large activity phase, splitting of free-running rhythms in constant darkness. In order to identify chromosomal location of the genes influencing free-running period, we analyzed F2 progeny from the cross between CS and C57BL/6J mice by QTL (Quantitative trait locus) mapping method. As a result, three provisional regions on chromosomes 4 (LOD score=3.5), 12 (LOD score=3.4) and 19 (LOD score=3.7) were detected. These potential QTLs are investigated in another cross with MSM mice and it was found that the same region on chromosome 19 is detected with LOD score 4.2. These results suggest that the free-running period of CS mice is affected by multiple genes and particularly the QTL on chromosome 19 strongly affect the period. The last mutation found during the crossing of mice is characterized by suddenly disorganized rhythm and sometimes 8 hr periodicity under constant darkness. For future studies, this mutant mice were maintained with an appropriate breeding method. Less

从原核生物到哺乳动物，几乎所有生物都观察到在恒定条件下由内源时钟驱动的昼夜节律，昼夜节律的特征是所有物种所共有的，但昼夜节律的分子机制尚不清楚。本研究的目的是分离小鼠的昼夜节律突变体，以了解昼夜节律的分子机制，为此，我们使用了 3 种不同的策略，一种是化学诱变。第三个是从野生小鼠群体中分离出突变体，利用这种策略，我们发现了一些表现出异常节律的突变体小鼠。此外，我们在繁殖小鼠的过程中意外地发现了另一个突变体。野生小鼠群体的特点是在恒定条件下昼夜节律丧失和昼夜节律周期缩短。遗传分析表明，心律失常性状是隐性的，因为突变体和 C57BL/6J 之间的 F1 小鼠表现出正常。 F2和回交中的节律和表型分离在自交系的筛选中，发现CS小鼠具有异常的昼夜节律特性，包括较长的自由奔跑时间、较长的活动阶段、在持续黑暗中自由奔跑节律的分裂。为了确定影响自由奔跑期的基因的染色体位置，我们通过 QTL（数量性状位点）作图方法对 CS 和 C57BL/6J 小鼠杂交的 F2 后代进行了分析，结果得到了 3 个结果。在与 MSM 小鼠的另一次杂交中检测到了 4 号染色体（LOD 得分 = 3.5）、12 号染色体（LOD 得分 = 3.4）和 19 号染色体（LOD 得分 = 3.7）上的临时区域。检测到 19 号染色体的 LOD 得分为 4.2 这些结果表明，CS 小鼠的强烈自由奔跑期受到多个基因的影响，尤其是 19 号染色体上的 QTL 影响该周期。在小鼠杂交过程中发现的突变的特点是节律突然紊乱，有时在持续黑暗的情况下出现8小时的周期性，为了以后的研究，这种突变小鼠采用适当的繁殖方法进行饲养。