Light entrained rhythmic gene expression in the sea anemone Nematostella vectensis: the evolution of the animal circadian clock.
Light entrained rhythmic gene expression in the sea anemone Nematostella vectensis: the evolution of the animal circadian clock.
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DOI：
10.1371/journal.pone.0012805
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发表时间：
2010-09-21
期刊：
影响因子：
3.7
通讯作者：
Tarrant AM
中科院分区：
文献类型：
--
作者：
Reitzel AM;Behrendt L;Tarrant AM
行为和生理的昼夜节律是从潜在分子成分的表达、相互作用和降解的循环中观察到的表型。在双边动物中，核心分子成分包括Timless-Timeout、感光隐色素和碱性环螺旋-Per-Arnt-Sim(bHLH-PAS)家族的几个成员。虽然许多核心昼夜节律基因在整个比拉特里亚都是保守的，但它们的具体作用因物种而异。在这里，我们鉴定和实验研究了海葵中保守的昼夜节律时钟成员的节律基因表达，以确定这种基因网络在蛇床纲的一个成员中的特征，并推断在蛇形动物和双边动物的最后一个共同祖先中使用的时钟的关键组成部分。我们在海葵中鉴定了昼夜节律调控基因的同源基因，包括一个与Timeout最相似的基因，三个隐色素基因，以及几个关键的bHLH-PAS转录因子。然后，我们在完全黑暗中或在12小时的光下：在三种不同的光处理下(仅蓝光、全光谱、蓝光耗尽)保持N.基因表达因光周期和光处理的不同而不同，其中NvClock的模式特别强烈。与光敏感的隐色素分支关系更密切的隐色素在包括蓝色波长的光处理中上调。通过免疫共沉淀法，我们确定了生物钟和周期之间的异源二聚作用在矢状核菌中是保守的。此外，我们确定了E-box基序，即时钟识别的DNA序列：循环异二聚体，基因上游显示有节奏的表达。这项研究揭示了生物钟的保守分子和功能成分，它们位于Cnidaria和Bilateria的分歧处，这表明动物的生物钟比之前的数据显示的更古老。描述爬行动物的昼夜节律特征有助于洞察动物昼夜节律的早期起源和环境提示行为的分子调控。
Circadian rhythms in behavior and physiology are the observable phenotypes from cycles in expression of, interactions between, and degradation of the underlying molecular components. In bilaterian animals, the core molecular components include Timeless-Timeout, photoreceptive cryptochromes, and several members of the basic-loop-helix-Per-ARNT-Sim (bHLH-PAS) family. While many of core circadian genes are conserved throughout the Bilateria, their specific roles vary among species. Here, we identify and experimentally study the rhythmic gene expression of conserved circadian clock members in a sea anemone in order to characterize this gene network in a member of the phylum Cnidaria and to infer critical components of the clockwork used in the last common ancestor of cnidarians and bilaterians. We identified homologs of circadian regulatory genes in the sea anemone Nematostella vectensis, including a gene most similar to Timeout, three cryptochromes, and several key bHLH-PAS transcription factors. We then maintained N. vectensis either in complete darkness or in a 12 hour light: 12 hour dark cycle in three different light treatments (blue only, full spectrum, blue-depleted). Gene expression varied in response to light cycle and light treatment, with a particularly strong pattern observed for NvClock. The cryptochromes more closely related to the light-sensitive clade of cryptochromes were upregulated in light treatments that included blue wavelengths. With co-immunoprecipitation, we determined that heterodimerization between CLOCK and CYCLE is conserved within N. vectensis. Additionally, we identified E-box motifs, DNA sequences recognized by the CLOCK:CYCLE heterodimer, upstream of genes showing rhythmic expression. This study reveals conserved molecular and functional components of the circadian clock that were in place at the divergence of the Cnidaria and Bilateria, suggesting the animal circadian clockwork is more ancient than previous data suggest. Characterizing circadian regulation in a cnidarian provides insight into the early origins of animal circadian rhythms and molecular regulation of environmentally cued behaviors.