冠轮动物（Lophotrochozoa，即Spiralia）几乎涵盖了所有的非蜕皮类原口动物，包括许多不同的动物门类。目前主要分为三个支系，即由软体动物、环节动物、纽形动物、腕足动物、帚虫动物和星虫动物门组成的担轮动物（Trochozoa），由环...冠轮动物（Lophotrochozoa，即Spiralia）几乎涵盖了所有的非蜕皮类原口动物，包括许多不同的动物门类。目前主要分为三个支系，即由软体动物、环节动物、纽形动物、腕足动物、帚虫动物和星虫动物门组成的担轮动物（Trochozoa），由环口动物、内肛动物和苔藓动物门组成的群居虫类（Polyzoa），以及由许多小的动物门类组成的扁形动物（Platyzoa）。最近，寒武纪大爆发期间冠轮动物的形态和系统学研究取得了很大的进展，但群居动物和扁形动物两大冠轮分支的化石记录几乎仍是空白。最近，西北大学早期生命研究所对新近收集的400多个瘤状杯形虫（Cotyledion tylodes Luo et Hu,1999）化石进行了重新研究，表明澄江化石库中早期发现的这类疑难类化石可能代表一类具骨骼的干群内肛动物。研究表明这类生物身体呈高足杯形，由杯形萼部和圆柱形的固着柄组成，固着柄的末端具有盘状的吸盘，用以附着在其他生物的外骨骼或身体上。杯体内具有U形的消化道，两端分别洞开于口和肛门，均包围在由一圈可自由伸缩的柔韧触手组成的纤毛环内。然而与现生的假体腔内肛动物相比，瘤状杯形虫个体较大，身体高度可达8～56 mm，身体表面覆盖一层疏松或紧密排列的圆形或椭圆形的骨片。另外，化石观察表明瘤状杯形虫固着柄的中央具有杯体向后延伸的体腔，属于有体腔类动物。因此，现生内肛动物体腔的丧失可能是衍征（apomorphy），其微型的身体以及解剖和体壁的简化可能是动物小型化作用（miniaturization）的结果，或者是现生内肛动物群居附着生活的适应性演化有关。具骨骼干群内肛动物的发现对理解早期冠轮生物的系统演化和相互关系有重要意义。展开更多
Many marine invertebrate phyla are characterized by indirect development.These animals transit from planktonic larvae to benthic spats via settlement and metamorphosis,which contributes to their adaption to the marine...Many marine invertebrate phyla are characterized by indirect development.These animals transit from planktonic larvae to benthic spats via settlement and metamorphosis,which contributes to their adaption to the marine environment.Studying the biological process of metamorphosis is,thus,key to understanding the origin and evolution of indirect development.Although numerous studies have been conducted on the relationship between metamorphosis and the marine environment,microorganisms,and neurohormones,little is known about gene regulation network(GRN)dynamics during metamorphosis.Metamorphosis-competent pediveligers of the Pacific oyster Crassostrea gigas were assayed in this study.By assaying gene expression patterns and open chromatin region changes of different samples of larvae and spats,the dynamics of molecular regulation during metamorphosis were examined.The results indicated significantly different gene regulation networks before,during and post-metamorphosis.Genes encoding membrane-integrated receptors and those related to the remodeling of the nervous system were upregulated before the initiation of metamorphosis.Massive biogenesis,e.g.,of various enzymes and structural proteins,occurred during metamorphosis as inferred from the comprehensive upregulation of the protein synthesis system post epinephrine stimulation.Hierarchical downstream gene networks were then stimulated.Some transcription factors,including homeobox,basic helix–loop–helix and nuclear receptors,showed different temporal response patterns,suggesting a complex GRN during the transition stage.Nuclear receptors,as well as their retinoid X receptor partner,may participate in the GRN controlling oyster metamorphosis,indicating an ancient role of the nuclear receptor regulation system in animal metamorphosis.展开更多
文摘冠轮动物（Lophotrochozoa，即Spiralia）几乎涵盖了所有的非蜕皮类原口动物，包括许多不同的动物门类。目前主要分为三个支系，即由软体动物、环节动物、纽形动物、腕足动物、帚虫动物和星虫动物门组成的担轮动物（Trochozoa），由环口动物、内肛动物和苔藓动物门组成的群居虫类（Polyzoa），以及由许多小的动物门类组成的扁形动物（Platyzoa）。最近，寒武纪大爆发期间冠轮动物的形态和系统学研究取得了很大的进展，但群居动物和扁形动物两大冠轮分支的化石记录几乎仍是空白。最近，西北大学早期生命研究所对新近收集的400多个瘤状杯形虫（Cotyledion tylodes Luo et Hu,1999）化石进行了重新研究，表明澄江化石库中早期发现的这类疑难类化石可能代表一类具骨骼的干群内肛动物。研究表明这类生物身体呈高足杯形，由杯形萼部和圆柱形的固着柄组成，固着柄的末端具有盘状的吸盘，用以附着在其他生物的外骨骼或身体上。杯体内具有U形的消化道，两端分别洞开于口和肛门，均包围在由一圈可自由伸缩的柔韧触手组成的纤毛环内。然而与现生的假体腔内肛动物相比，瘤状杯形虫个体较大，身体高度可达8～56 mm，身体表面覆盖一层疏松或紧密排列的圆形或椭圆形的骨片。另外，化石观察表明瘤状杯形虫固着柄的中央具有杯体向后延伸的体腔，属于有体腔类动物。因此，现生内肛动物体腔的丧失可能是衍征（apomorphy），其微型的身体以及解剖和体壁的简化可能是动物小型化作用（miniaturization）的结果，或者是现生内肛动物群居附着生活的适应性演化有关。具骨骼干群内肛动物的发现对理解早期冠轮生物的系统演化和相互关系有重要意义。
基金supported by the Oceanographic Data Center,IOCAS.We acknowledge financial support from the Science&Technology Innovation Project of Laoshan Laboratory(LSKJ202203001)the Key Research and Development Program of Shandong(2022LZGC015),and the Taishan Scholars Program.
文摘Many marine invertebrate phyla are characterized by indirect development.These animals transit from planktonic larvae to benthic spats via settlement and metamorphosis,which contributes to their adaption to the marine environment.Studying the biological process of metamorphosis is,thus,key to understanding the origin and evolution of indirect development.Although numerous studies have been conducted on the relationship between metamorphosis and the marine environment,microorganisms,and neurohormones,little is known about gene regulation network(GRN)dynamics during metamorphosis.Metamorphosis-competent pediveligers of the Pacific oyster Crassostrea gigas were assayed in this study.By assaying gene expression patterns and open chromatin region changes of different samples of larvae and spats,the dynamics of molecular regulation during metamorphosis were examined.The results indicated significantly different gene regulation networks before,during and post-metamorphosis.Genes encoding membrane-integrated receptors and those related to the remodeling of the nervous system were upregulated before the initiation of metamorphosis.Massive biogenesis,e.g.,of various enzymes and structural proteins,occurred during metamorphosis as inferred from the comprehensive upregulation of the protein synthesis system post epinephrine stimulation.Hierarchical downstream gene networks were then stimulated.Some transcription factors,including homeobox,basic helix–loop–helix and nuclear receptors,showed different temporal response patterns,suggesting a complex GRN during the transition stage.Nuclear receptors,as well as their retinoid X receptor partner,may participate in the GRN controlling oyster metamorphosis,indicating an ancient role of the nuclear receptor regulation system in animal metamorphosis.
