Analysis of a new circadian mutant

描述（由申请人提供）：我们在叙利亚仓鼠中发现了一种新的自发性昼夜节律突变，其赋予动物运动节律稳健的表型。突变纯合子动物的自由奔跑时间约为28小时，每天周期比野生型动物长4小时。此类突变大多数是通过化学诱变在小鼠中产生的，对于了解我们迄今为止所知道的关于哺乳动物产生细胞自主昼夜节律的分子机制至关重要，但我们的知识还远不完整，很明显，额外的未知基因必须有助于其功能。此外，由于仓鼠在行为和生理研究方面比小鼠具有许多优势，这种新的突变为哺乳动物生物钟机制的研究提供了独特的机会。我们建议在3个水平上分析这种新的突变：遗传，行为和分子。遗传分析将测试我们的假设，根据初步数据，突变是一个单一的，常染色体共显性等位基因。Menaker实验室的工作将集中在行为表型上，并将探索两种性别的野生型、杂合和纯合同窝仔对恒定黑暗、恒定光照、单次光脉冲、具有不同光/暗比率的光周期和具有不同周期的夹带周期的反应，这些数据将解决突变基因在昼夜节律分子机制中的作用以及其对生物体生理的影响。绿色实验室将对这些突变体进行分子和生化分析，以确定这种突变是否影响核心细胞内振荡器机制或某些系统水平方面，如细胞间耦合。突变的性质将通过对已知的昼夜节律基因进行测序并分析其表达水平来解决。这也将为最终通过全基因组测序鉴定突变奠定重要基础。昼夜节律调节许多正常的生理和行为，昼夜节律的破坏增加了对各种环境损害的脆弱性。了解潜在的机制对于控制这些有害影响至关重要。 公共卫生相关性：从大脑延伸到周围每个结构的昼夜节律振荡器网络已经进化到维持自然环境中的内部时间秩序。然而，人类对自己的“非自然”环境所做的许多改变使这个系统受到了压力，内部的时间秩序被打乱了。为了减轻昼夜节律紊乱对人类健康的有害影响，有必要从分子水平上详细了解完整的和被破坏的系统。

DESCRIPTION (provided by applicant): We have discovered a new spontaneous circadian mutation in Syrian hamsters, which confers a robust phenotype on the animals' locomotor rhythmicity. The free running period of animals homozygous for the mutation is approximately 28 hours, 4 hours per daily cycle longer than that of wild type animals. Such mutations, most produced in mice by chemical mutagenesis, have been critical in working out what we know thus far about the molecular mechanism that generates cell autonomous circadian rhythmicity in mammals, but our knowledge is far from complete and it is clear that additional unidentified genes must contribute to its function. Furthermore, because hamsters provide many advantages over mice for behavioral and physiological studies, this new mutation provides a unique opportunity for studies of the circadian clock mechanism in mammals. We propose to analyze this new mutation at 3 levels: genetic, behavioral and molecular. Genetic analysis will test our assumption, based on preliminary data, that the mutation is a single, autosomal co-dominant allele. The work in the Menaker laboratory will be focused on the behavioral phenotype and will explore the responses of wild type, heterozygous and homozygous littermates of both sexes to constant darkness, constant light, single light pulses, photoperiods with different light/dark ratis and entraining cycles with different periods, These data will address the role of the mutant gene in the circadian molecular mechanism as well as its impact on the organism's physiology. The Green lab will perform molecular and biochemical analysis of these mutants to determine whether this mutation affects the core intracellular oscillator mechanism or some system-level aspect, such as intercellular coupling. The nature of the mutation will be addressed by sequencing of the known circadian genes, and by analysis of their expression levels. This will also lay important groundwork for the eventual identification of the mutation by whole-genome sequencing. Circadian rhythms modulate much of normal physiology and behavior and circadian disruptions increase vulnerability to a variety of environmental insults. Knowledge of the underlying mechanism is essential to controlling these deleterious effects. PUBLIC HEALTH RELEVANCE: The network of circadian oscillators that stretches from the brain to every structure in periphery has evolved to maintain internal temporal order in the natural environment. However, this system is stressed and internal temporal order is disrupted by many of the changes that humans have made to their own "unnatural" environments. In order to mitigate the deleterious effects of circadian disruption on human health, it is necessary to understand the intact and the disrupted system in molecular detail.