Animal Physiology, Department of Biology, Faculty of Mathematics and Natural Sciences (FB 10), University of Kassel, Kassel, Germany.
J Biol Rhythms. 2012 Dec;27(6):453-66. doi: 10.1177/0748730412462109.
Most of what we know today about the molecular constituents of the insect circadian clock was discovered in the fruit fly Drosophila melanogaster. Various other holometabolous and some hemimetabolous insects have also been examined for the presence of circadian genes. In these insects, per, tim1, and cry2 are part of a core feedback loop system. The proteins inhibit their own expression, leading to circadian oscillations of mRNA and proteins. Although cockroaches are successfully employed circadian model organisms, their clock genes are mostly unknown. Thus, we cloned putative circadian genes in Rhyparobia maderae (synonym Leucophaea maderae), showing the presence of period (per), timeless 1 (tim1), and mammalian-type cryptochrome (cry2). The expression levels of per, tim1, and cry2 in R. maderae were examined in various tissues and photoperiods employing quantitative PCR. In brains and excised accessory medullae, expression levels of rmPer, rmTim1, and rmCry2 oscillated in a circadian manner with peaks in the first half of the night. Oscillations mostly continued in constant conditions. In Malpighian tubules, no significant oscillations were found. In animals raised in different photoperiods (LD 18:6, 12:12, 6:18), the peak levels of rmPer, rmTim1, and rmCry2 expression adjusted with respect to the beginning of the scotophase. The daily mean of expression levels was significantly lower in short-day versus long-day animals. We suggest that rmPer, rmTim1, and rmCry2 are part of the Madeira cockroach nuclear circadian clock, which can adjust to different photoperiods.
我们今天对昆虫生物钟的分子组成的了解大多是在黑腹果蝇果蝇中发现的。各种其他全变态和一些半变态昆虫也被检查是否存在生物钟基因。在这些昆虫中，per、tim1 和 cry2 是核心反馈回路系统的一部分。这些蛋白质抑制自身的表达，导致 mRNA 和蛋白质的昼夜节律振荡。虽然蟑螂被成功地用作生物钟模型生物，但它们的生物钟基因大多是未知的。因此，我们在 Rhyparobia maderae（同义词 Leucophaea maderae）中克隆了推定的生物钟基因，显示出 period（per）、timeless 1（tim1）和哺乳动物型隐色素（cry2）的存在。使用定量 PCR 检查了 R. maderae 在各种组织和光周期中的 per、tim1 和 cry2 的表达水平。在大脑和切除的附加髓质中，rmPer、rmTim1 和 rmCry2 的表达水平以昼夜节律的方式波动，峰值出现在夜间的前半段。振荡在恒常条件下大多继续。在马氏小管中，没有发现明显的振荡。在不同光周期（LD 18:6、12:12、6:18）下饲养的动物中，rmPer、rmTim1 和 rmCry2 表达的峰值水平相对于暗期的开始进行调整。短日与长日动物相比，表达水平的日均值显著降低。我们认为 rmPer、rmTim1 和 rmCry2 是马德拉蟑螂核生物钟的一部分，可以适应不同的光周期。
