IntroductionMany marine organisms have a biphasic life cycle that transitions between a swimming larva with a more sedentary adult form. At the end of the first phase, larvae must identify suitable sites to settle and undergo a dramatic morphological change. Environmental factors, including photic and chemical cues, appear to influence settlement, but the sensory receptors involved are largely unknown. We targeted the protein receptor, opsin, which belongs to large superfamily of transmembrane receptors that detects environmental stimuli, hormones, and neurotransmitters. While opsins are well-known for light-sensing, including vision, a growing number of studies have demonstrated light-independent functions. We therefore examined opsin expression in the Pteriomorphia, a large, diverse clade of marine bivalves, that includes commercially important species, such as oysters, mussels, and scallops.MethodsGenomic annotations combined with phylogenetic analysis show great variation of opsin abundance among pteriomorphian bivalves, including surprisingly high genomic abundance in many species that are eyeless as adults, such as mussels. Therefore, we investigated the diversity of opsin expression from the perspective of larval development. We collected opsin gene expression in four families of Pteriomorphia, across three distinct larval stages, i.e., trochophore, veliger, and pediveliger, and compared those to adult tissues.ResultsWe found larvae express all opsin types in these bivalves, but opsin expression patterns are largely species-specific across development. Few opsins are expressed in the adult mantle, but many are highly expressed in adult eyes. Intriguingly, opsin genes such as retinochrome, xenopsins, and Go-opsins have higher levels of expression in the later larval stages when substrates for settlement are being tested, such as the pediveliger.ConclusionInvestigating opsin gene expression during larval development provides crucial insights into their intricate interactions with the surroundings, which may shed light on how opsin receptors of these organisms respond to various environmental cues that play a pivotal role in their settlement process.

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翼形双壳类幼虫发育和分类群中视蛋白的表达存在差异

简介许多海洋生物具有双相生命周期，在游泳的幼虫和更静止的成体之间过渡。在第一阶段结束时，幼虫必须找到合适的地点定居并经历剧烈的形态变化。环境因素，包括光和化学信号，似乎会影响沉降，但所涉及的感觉受体在很大程度上是未知的。我们的目标是蛋白质受体视蛋白，它属于跨膜受体大家族，可检测环境刺激、激素和神经递质。虽然视蛋白因光感应（包括视觉）而闻名，但越来越多的研究已经证明了与光无关的功能。因此，我们检查了翼形目（Pteriomorphia）中的视蛋白表达，翼形目是海洋双壳类的一个大型多样化分支，其中包括商业上重要的物种，如牡蛎、贻贝和扇贝。方法基因组注释与系统发育分析相结合显示翼形双壳类中视蛋白丰度的巨大差异，包括许多成年后没有眼睛的物种（例如贻贝）的基因组丰度惊人地高。因此，我们从幼虫发育的角度研究了视蛋白表达的多样性。我们收集了翼形纲四个科的视蛋白基因表达，跨越三个不同的幼虫阶段，即轮轮、veliger和pediveliger，并将其与成体组织进行比较。结果我们发现这些双壳类幼虫表达所有视蛋白类型，但视蛋白表达模式很大程度上是不同的跨发展的物种特异性。成体外套膜中很少表达视蛋白，但许多视蛋白在成体眼睛中高度表达。有趣的是，当测试沉降底物（如pediveliger）时，视蛋白基因（如视黄色素、xenopsins和Go-opsins）在幼虫后期具有更高水平的表达。结论研究幼虫发育过程中的视蛋白基因表达为了解其复杂性提供了重要的见解。与周围环境的相互作用，这可能有助于了解这些生物体的视蛋白受体如何响应在其定居过程中发挥关键作用的各种环境因素。