Evolution of Insect Circadian Clocks and Light Input Channels

昆虫昼夜节律钟和光输入通道的进化

• 批准号: 0646060
• 负责人: Adriana Briscoe
• 金额: $ 50万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-15 至 2010-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0646060&HistoricalAwards=false
• 关键词: Evolution; Insect; Circadian; Clocks; Light

Bees are important pollinators of land plants, and they display robust circadian (ca. 24 hr) rhythms when foraging. Yet little is known about the circadian clock in the brains of bees and its light input channels. Cryptochromes (CRYs) and opsins are light-sensitive molecules that mediate the entrainment of circadian clocks by the external light cycle. Prior to the radiation of metazoans at least one gene duplication event occurred pergene family creating both vertebrate-like opsins (CRY2) and Drosophila-like cryptochrome (CRY1). These investigators discovered the CRY2 gene in non-drosophilid insects. While Drosophila only express CRY1, mosquitos and butterflies express both CRY1 and CRY2, and bees and beetles only express CRY2. These three different expression patterns for the two CRY genes suggest potentially three different types of insect clocks.Honeybees and bumblebees are a model system for examining the function of vertebrate-like opsin and cryptochrome in insects, because they represent one of the three ways within insects in which circadian clocks have evolved, with a vertebrate-like CRY (insect CRY2) but without a Drosophila-like CRY (insect CRY1). This project will evaluate the molecular clockwork in bees using molecular, biochemical and anatomical approaches. The molecular clock's transcriptional feedback loop will be reconstructed in cell culture using CRY2 and bee homologs of other clock proteins (such as 'period'). Anatomical methods will map the location of circadian clock and opsin proteins in the brain and eye. The temporal profiles of cry2 and period RNA and protein levels will be examined in bee heads, and the critical protein-protein interactions defined. Moreover, Drosophila transgenesis and RNA interference approaches will examine in vivo the function of bee CRY2. Finally, light input pathways to the bee clock will be evaluated, and the light sensitivity of the vertebrate-like opsin will be studied in cell culture. As bees are already famously used for behavioral investigations, the results of these studies will define a novel circadian clockwork mechanism and define specific neuroanatomical pathways that could in future studies be manipulated to determine their impact on behavioral outputs. This project will provide an excellent training environment for undergraduate and graduate students by using multi-level integrated approaches to study how circadian systems have evolved, from sensory input to integrating centers.

蜜蜂是陆地植物的重要传粉者，它们在觅食时表现出强烈的昼夜节律(约24小时)。然而，人们对蜜蜂大脑中的生物钟及其光输入通道知之甚少。隐色素(Crys)和视蛋白(Opsins)是光敏分子，它们通过外部光周期调节生物钟的携带。在后生动物受到辐射之前，至少发生了一个基因复制事件，产生了类似脊椎动物的视蛋白(CRY2)和类果蝇的隐花色素(CRY1)。这些研究人员在非果蝇昆虫中发现了CRY2基因。果蝇只表达CRY1，蚊子和蝴蝶都表达CRY1和CRY2，蜜蜂和甲虫只表达CRY2。这两种叫声基因的这三种不同的表达模式可能暗示了三种不同类型的昆虫时钟。蜜蜂和大黄蜂是研究昆虫中类似脊椎动物的视蛋白和隐色素功能的模式系统，因为它们代表了昆虫体内生物钟进化的三种方式之一，有脊椎动物般的叫声(昆虫CRY2)，但没有果蝇般的叫声(昆虫CRY1)。该项目将使用分子、生化和解剖学方法来评估蜜蜂的分子发条。分子时钟的转录反馈环将在细胞培养中使用CRY2和其他时钟蛋白的蜜蜂同源物(如PERIOD)重建。解剖学方法将绘制出生物钟和视蛋白在大脑和眼睛中的位置。将研究蜜蜂头部中Cry2和周期RNA和蛋白质水平的时间分布，并定义关键的蛋白质-蛋白质相互作用。此外，果蝇转基因和RNA干扰方法将在体内检测蜜蜂CRY2的功能。最后，将评估蜜蜂时钟的光输入路径，并将在细胞培养中研究脊椎动物样视蛋白的光敏感度。由于蜜蜂已经被著名地用于行为研究，这些研究的结果将定义一种新的昼夜时钟机制，并定义特定的神经解剖学路径，这些路径可以在未来的研究中被操纵，以确定它们对行为输出的影响。该项目将为本科生和研究生提供一个良好的培训环境，通过使用多层次的综合方法来研究从感觉输入到整合中心的昼夜节律系统是如何演变的。