Development of somites and their derivatives in amphioxus, and implications for the evolution of vertebrate somites.
Development of somites and their derivatives in amphioxus, and implications for the evolution of vertebrate somites.
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DOI：
10.1186/s13227-015-0007-5
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发表时间：
2015
期刊：
影响因子：
4.1
通讯作者：
Brent AE
中科院分区：
文献类型：
--
作者：
Mansfield JH;Haller E;Holland ND;Brent AE
脊椎动物体节被细分为谱系区室，每个区室具有不同的细胞命运和进化历史。体节进化的洞察力可以来自对文昌鱼的研究，文昌鱼是脊索动物祖先现存最接近的物种。文昌鱼体节分为肌节和非肌节两部分，但后者的发育和命运尚不完全清楚。此外，虽然上皮间质转化（EMT）是重要的大多数脊椎动物体节谱系，文昌鱼体节一般被认为是保持完全上皮。在这里，我们研究文昌鱼体节和衍生物，以及细胞外基质的轴向支持系统，在一系列的发展阶段，通过透射电子显微镜（TEM）和原位杂交胶原蛋白的表达。文昌鱼体节内侧分化为肌节，外侧分化为外细胞层（真皮下的间皮），腹侧分化为形成内脏周围体腔间皮的芽，腹内侧分化为硬节。硬节最初形成为单层细胞片，在肌节、脊索和神经管之间迁移;随后，该细胞片变成双层并包围硬腔。其他的晚期发展包括从侧体节形成鳍盒间皮和分离的成纤维细胞的出现，可能是体节衍生的，沿着肌隔。在整个发育过程中，所有源自体节的非肌节区域的细胞强烈表达纤维状胶原基因ColA，因此可能有助于真皮和轴向结缔组织系统的细胞外基质。我们提供了一个修改后的模型文昌鱼的硬骨鱼和鳍盒的发展，并确认以前的报告的肌节和侧体节的发展。此外，虽然体节衍生物几乎完全保持上皮，但有限的去上皮化可能将一些体节细胞转化为肌间隔和真皮的成纤维细胞。超微结构和胶原蛋白表达表明，所有非肌节体节衍生物有助于真皮和轴向支持系统的细胞外基质。虽然文昌鱼的硬骨鱼缺乏脊椎动物一样的EMT，它类似于脊椎动物的位置，运动，围绕中线结构，并进入肌隔膜，和轴向支持系统的细胞外基质的贡献。因此，在脊椎动物矿化骨骼的起源之前，硬骨节发育程序的许多方面已经进化。
Vertebrate somites are subdivided into lineage compartments, each with distinct cell fates and evolutionary histories. Insights into somite evolution can come from studying amphioxus, the best extant approximation of the chordate ancestor. Amphioxus somites have myotome and non-myotome compartments, but development and fates of the latter are incompletely described. Further, while epithelial to mesenchymal transition (EMT) is important for most vertebrate somitic lineages, amphioxus somites generally have been thought to remain entirely epithelial. Here, we examined amphioxus somites and derivatives, as well as extracellular matrix of the axial support system, in a series of developmental stages by transmission electron microscopy (TEM) and in situ hybridization for collagen expression. The amphioxus somite differentiates medially into myotome, laterally into the external cell layer (a sub-dermal mesothelium), ventrally into a bud that forms mesothelia of the perivisceral coelom, and ventro-medially into the sclerotome. The sclerotome forms initially as a monolayered cell sheet that migrates between the myotome and the notochord and neural tube; subsequently, this cell sheet becomes double layered and encloses the sclerocoel. Other late developments include formation of the fin box mesothelia from lateral somites and the advent of isolated fibroblasts, likely somite derived, along the myosepta. Throughout development, all cells originating from the non-myotome regions of somites strongly express a fibrillar collagen gene, ColA, and thus likely contribute to extracellular matrix of the dermal and axial connective tissue system. We provide a revised model for the development of amphioxus sclerotome and fin boxes and confirm previous reports of development of the myotome and lateral somite. In addition, while somite derivatives remain almost entirely epithelial, limited de-epithelialization likely converts some somitic cells into fibroblasts of the myosepta and dermis. Ultrastructure and collagen expression suggest that all non-myotome somite derivatives contribute to extracellular matrix of the dermal and axial support systems. Although amphioxus sclerotome lacks vertebrate-like EMT, it resembles that of vertebrates in position, movement to surround midline structures and into myosepta, and contribution to extracellular matrix of the axial support system. Thus, many aspects of the sclerotome developmental program evolved prior to the origin of the vertebrate mineralized skeleton.
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影响因子：
64.8
作者：
Freitas, Renata;Zhang, GuangJun;Cohn, Martin J.
通讯作者：
Cohn, Martin J.
影响因子：
3.7
作者：
Bricard, Yoann;Ralliere, Cecile;Rescan, Pierre-Yves
通讯作者：
Rescan, Pierre-Yves
影响因子：
2.5
作者：
Bocina, Ivana;Ljubesic, Nikola;Saraga-Babic, Mirna
通讯作者：
Saraga-Babic, Mirna
影响因子：
2.4
作者：
Beaster-Jones, Laura;Kaltenbach, Stacy L.;Holland, Linda Z.
通讯作者：
Holland, Linda Z.
影响因子：
4.6
作者：
Brent, AE;Tabin, CJ
通讯作者：
Tabin, CJ