Effects of combining a cryptochrome mutation with other visual-system variants on entrainment of locomotor and adult-emergence rhythms in Drosophila
Effects of combining a cryptochrome mutation with other visual-system variants on entrainment of locomotor and adult-emergence rhythms in Drosophila
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DOI：
10.1080/01677060390256422
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发表时间：
2003-04-01
影响因子：
1.9
通讯作者：
Hall, JC
中科院分区：
文献类型：
--
作者：
Mealey-Ferrara, ML;Montalvo, AG;Hall, JC
光感受是节律系统的重要组成部分，参与调整生物钟以适应每日周期的光特征。在果蝇中，有人提出，生物钟有三种光输入途径，构成了成年行为节律的基础：一是眼睛；二是通过眼睛。另外两种是通过称为 Hofbauer-Buchner (H-B) 孔眼的结构进行的眼外光接收，以及由起搏器神经元本身进行的光接收，由一种称为隐花色素的物质介导。据推测，包括 H-B 孔眼在内的所有感光细胞都被玻璃无效突变去除。无受体电位 A (norpA) 基因的突变会导致复眼和单眼无功能，也可能影响眼孔的功能。已知的一种隐花色素突变体（cry(b)）在该基因编码的蓝光吸收蛋白中存在氨基酸取代。关于成年运动节律，所有单突变体（gl（60j）、norpA（P41）和cry（h））重新进入改变的光：暗（LD）循环，其中L期涉及相对强的光。降低光照水平约。 10 或约。 30倍允许小比例的双突变gl(60j)cry(b)明显地飞行以重新同步它们的行为。然而，与之前使用不同的再夹带方案观察到的结果相比，最低光照情况下的边际再夹带性涉及 gl(60j)cry(b) 类型的优异响应性。此外，H-B孔眼内表达视紫红质的细胞被消融或受到破伤风毒素影响的转基因类型在低光水平下也表现出与gl(60j)cry(b)类似或优于gl(60j)cry(b)的行为。同步周期性成年羽化所必需的光输入可以推断（从以前的研究）涉及一种依赖于cry的途径，也可能涉及一种依赖于norpA的途径，因此这两个基因中的突变的组合将导致培养物不可夹带。目前的结果是，每种单突变类型都有节奏地出现。从norpA(P41);cry(b)中出现的果蝇，培养物也（总的来说）表现出坚实的羽化节律性。这些行为和成人出现结果的集合表明，额外的光到时钟通路在系统内发挥作用。或者，这里使用的节律测定已经弄清楚了突变的 CRY 蛋白的残余功能。
Photoreception is an important component of rhythm systems and is involved in adjusting circadian clocks to photic features of daily cycles. In Drosophila, it has been suggested that there are three light input pathways to the clock that underlie rhythms of adult behavior: One involves the eyes; the other two extraocular photoreception through a structure called the Hofbauer-Buchner (H-B) eyelet and light reception carried out by pacemaker neurons themselves., mediated by a substance called cryptochrome. All photoreceptor cells including the H-B eyelet have been surmised to be removed by glass-null mutations. Mutations in the no-receptor-potential-A (norpA) gene cause the compound eyes and ocelli to be non-functional and may also affect the eyelet's function. The one cryptochrome mutant known (cry(b)) harbors an aminoacid substitution in the blue-light absorbing protein encoded by this gene. With regard to adult locomotor rhythms, all single mutants (gl(60j), norpA(P41), and cry(h)) re-entrained to altered light:dark (LD) cycles in which the L phase involved relatively intense light. Dropping light levels ca. 10 or ca. 30-fold permitted small percentages of doublymutant gl(60j) cry(b) flies clearly to re-synchronize their behavior. The marginal re-entrainability in the lowest-light situation nevertheless involved superior responsiveness of the gl(60j) cry(b) type, compared with that observed previously using a different re-entrainment protocol. Furthermore, transgenic types in which rhodopsin-expressing cells within the H-B eyelet were ablated or suffered from the effects of tetanus-toxin also entrained with behavior similar or superior to that of gl(60j) cry(b) at a low light level. Light inputs that are necessary to synchronize periodic adult emergence can be inferred (from previous studies) to involve a cry-dependent pathway and perhaps also a norpA-dependent one, so that combining mutations in these two genes would cause cultures to be unentrainable. The Current results were that each singly-mutant type eclosed rhythmically; flies emerging from norpA(P41);cry(b), cultures also (on balance) exhibited solid eclosion rhythmicity. The ensemble of these behavioral and adult-emergence results suggest that additional light-to-clock pathways function within the system; alternatively, that rhythm assays employed here have teased out residual function of the mutated CRY protein.