Characterization of a Novel Circadian Clock in Drosophila Excretory Organ

昼夜节律在生物体中无处不在，在生化、生理和行为水平上同步生命功能。节奏产生机制。统称为生物钟的生物钟，在任何生物体中都没有被完全理解。对果蝇的研究使我们对昼夜节律机制的分子基础有了重要的认识。两个时钟基因，周期和永恒，已被证明在控制成年果蝇行为节奏的以大脑为中心的时钟的功能中发挥核心作用。利用这些基因作为标记，PI在果蝇的排泄器官马氏小管中发现了一种新的生物钟，并确定这种生物钟在没有大脑的情况下也能发挥作用。PI计划研究排泄器官中的外周时钟与中枢神经系统中的起搏器之间的关系。实验将涉及器官移植和体外培养，使用携带荧光素酶报告基因的新型转基因果蝇，这可以实时持续测量时钟基因的mRNA水平。PI希望在马氏小管中建立外周时钟的自主程度，并测试其他组织如何影响其功能。PI还将探索光感受器的性质，光感受器介导生物钟的重置，并研究生物钟在排泄器官中的功能作用。在这一追求中，PI试图回答一个基本问题，即果蝇的昼夜节律系统是一个集中的系统，由一个控制所有节律功能的主导时钟组成，还是一个分散的系统，由位于不同组织中的几个独立时钟组成，控制着生理功能的子集。马氏小管在生理和分子遗传学研究中都是独一无二的。该建议的广泛范围将允许彻底表征该组织中的昼夜节律钟。为未来的研究提供动力，旨在了解已经确定的时钟基因如何一方面接受环境输入，另一方面产生有节奏的输出。

Circadian rhythms are ubiquitous in the living organisms, synchronizing life functions at the biochemical, physiological, and behavioral levels. The rhythms generating mechanisms. collectively known as circadian clocks, are not fully understood in any organism. Research in the fruit fly Drosophila has led to major insights into the molecular bases of the circadian mechanism. Two clock genes, period and timeless, have been shown to play central roles in the function of the brain-centered clock, which controls behavioral rhythms of adult flies. Using those genes as markers, the PI has identified a new circadian clock in the fly excretory organ, the Malpighian tubules and established that this clock can function in the absence of the brain. The PI plans to study the relationships between the peripheral clock in the excretory organ and pacemakers in the central nervous system. Experiments will involve organ transplants and in vitro cultures, using novel strains of transgenic flies carrying luciferase reporter, which allows real time continuing measurement of mRNA levels of clock genes. The PI wishes to establish the degree of autonomy of the peripheral clock in the Malpighian tubules and to test how other tissues affect its function. The PI will also probe the nature of the photoreceptor that mediate the resetting of the clock by light and investigate the functional role of the clock in the excretory organ. In this pursuit, the PI seek to answer a fundamental question of whether the circadian system in Drosophila is a centralized one, comprised of a single dominant clock that would control all rhythmic functions, or is a decentralized system with several independent clocks located in different tissues and controlling subsets of physiological functions. Malpighian tubules are uniquely accessible to both physiological and molecular genetic investigations. The broad scope of this proposal will allow thorough characterization of the circadian clock in this tissue. providing impetus for future resear ch aimed at understanding how already identified clock genes receive environmental input on one hand, and produce rhythmic outputs on the other.