Vogeler Susanne, Bean Tim P, Lyons Brett P, Galloway Tamara S
School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
Centre for Environment, Fisheries and Aquaculture Science, Cefas Weymouth Laboratory, Barrack Road, Weymouth, DT4 8UB, UK.
BMC Dev Biol. 2016 Sep 29;16(1):33. doi: 10.1186/s12861-016-0129-6.
Nuclear receptors are a highly conserved set of ligand binding transcription factors, with essential roles regulating aspects of vertebrate and invertebrate biology alike. Current understanding of nuclear receptor regulated gene expression in invertebrates remains sparse, limiting our ability to elucidate gene function and the conservation of developmental processes across phyla. Here, we studied nuclear receptor expression in the early life stages of the Pacific oyster, Crassostrea gigas, to identify at which specific key stages nuclear receptors are expressed RESULTS: We used quantitative RT-PCR to determine the expression profiles of 34 nuclear receptors, revealing three developmental key stages, during which nuclear receptor expression is dynamically regulated: embryogenesis, mid development from gastrulation to trochophore larva, and late larval development prior to metamorphosis. Clustering of nuclear receptor expression patterns demonstrated that transcriptional regulation was not directly related to gene phylogeny, suggesting closely related genes may have distinct functions. Expression of gene homologs of vertebrate retinoid receptors suggests participation in organogenesis and shell-formation, as they are highly expressed at the gastrulation and trochophore larval initial shell formation stages. The ecdysone receptor homolog showed high expression just before larval settlement, suggesting a potential role in metamorphosis.
Throughout early oyster development nuclear receptors exhibited highly dynamic expression profiles, which were not confined by gene phylogeny. These results provide fundamental information on the presence of nuclear receptors during key developmental stages, which aids elucidation of their function in the developmental process. This understanding is essential as ligand sensing nuclear receptors can be disrupted by xenobiotics, a mode of action through which anthropogenic environmental pollutants have been found to mediate effects.
核受体是一组高度保守的配体结合转录因子，在调节脊椎动物和无脊椎动物生物学方面均发挥着重要作用。目前对无脊椎动物中核受体调控基因表达的了解仍然有限，这限制了我们阐明基因功能以及跨门发育过程保守性的能力。在此，我们研究了太平洋牡蛎（Crassostrea gigas）早期生命阶段的核受体表达，以确定核受体在哪些特定关键阶段表达。
我们使用定量逆转录聚合酶链反应（qRT-PCR）来确定34种核受体的表达谱，揭示了三个发育关键阶段，在此期间核受体表达受到动态调控：胚胎发生、从原肠胚形成到担轮幼虫的中期发育以及变态前的后期幼虫发育。核受体表达模式的聚类表明转录调控与基因系统发育没有直接关系，这表明密切相关的基因可能具有不同的功能。脊椎动物类视黄醇受体基因同源物的表达表明它们参与器官发生和贝壳形成，因为它们在原肠胚形成和担轮幼虫初始贝壳形成阶段高度表达。蜕皮激素受体同源物在幼虫附着前表达量很高，表明其在变态过程中可能发挥作用。
在牡蛎早期发育过程中，核受体表现出高度动态的表达谱，不受基因系统发育的限制。这些结果提供了关于关键发育阶段核受体存在的基本信息，有助于阐明它们在发育过程中的功能。这种理解至关重要，因为配体感应核受体可能会被外源性物质破坏，而这是人为环境污染物介导效应的一种作用方式。
