Germline development during embryogenesis of the larvacean, Oikopleura dioica.
Germline development during embryogenesis of the larvacean, Oikopleura dioica.
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幼虫 Oikopleura dioica 胚胎发生过程中的种系发育。
DOI：
10.1016/j.ydbio.2021.10.009
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
and Onuma T.A.
中科院分区：
文献类型：
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作者：
Nishida;H.;Matsuo;M.;Konishi;S.;Ohno;N.;Manni;L.;and Onuma T.A.
生殖细胞发育成卵子和精子，并代表了一个经过多代生存的谱系。在胚胎发生过程中，生殖细胞的特化通过两种基本模式之一进行：细胞自主模式或诱导模式。在细胞自主模式中，生殖细胞命运的特化涉及到特化的母体细胞质的不对称分配，称为种质。Oikopleura dioicais是一种幼虫类（Applyularia纲）和脊索动物。由于其生命周期短（5天）和基因组小（约60 Mb），它被认为是研究脊索动物发育的一个有前途的动物模型。我们表明，它们的胚胎具有种质，海鞘类（类海鞘）中观察到的。在第一次分裂发生之前，植物细胞质向未来的后极移动。在32细胞期，经两轮不等分裂，在后极形成一对原始生殖细胞（PGC，B11细胞）。这些B11细胞在蝌蚪形幼虫孵化前没有进行进一步的分裂。中心体吸引体（CAB）是海鞘类生殖细胞的一种亚细胞结构，在生殖细胞发育过程中起着重要作用。通过电子显微镜和提取的胚胎观察到CAB与种质的存在在幼虫的生殖谱系细胞。CAB出现在8细胞期，并持续到胚胎发育中期。磷酸化组蛋白3抗体的抗原定位于CAB，并持续存在于PGC中，直到CAB消失后孵化。编码转录因子的母螺mRNA与H3S28p抗体的抗原共定位。此外，我们发现了一种新的PGC特异性亚细胞结构，我们称之为生殖体（GB）。因此，这项研究突出了海鞘和幼虫之间的生殖细胞发育的保守和非保守的功能。异源稻的快速发育和短生命周期（5天）为将来从遗传学角度分析生殖细胞发育开辟了道路。
Germ cells develop into eggs and sperms and represent a lineage that survives through multiple generations. Germ cell specification during embryogenesis proceeds through one of two basic modes: either the cell-autonomous mode or the inductive mode. In the cell-autonomous mode, specification of germ cell fate involves asymmetric partitioning of the specialized maternal cytoplasm, known as the germplasm.Oikopleura dioicais a larvacean (class Appendicularia) and a chordate. It is regarded as a promising animal model for studying chordate development because of its short life cycle (5 days) and small genome size (∼60 Mb). We show that their embryos possess germplasm, as observed in ascidians (class Ascidiacea). The vegetal cytoplasm shifted towards the future posterior pole before the first cleavage occurred. A bilateral pair of primordial germ cells (PGC, B11 cells) was formed at the posterior pole at the 32-cell stage through two rounds of unequal cleavage. These B11 cells did not undergo further division before hatching of the tadpole-shaped larvae. The centrosome-attracting body (CAB) is a subcellular structure that contains the germplasm and plays crucial roles in germ cell development in ascidians. The presence of CAB with germplasm was observed in the germline lineage cells of larvaceans via electron microscopy and using extracted embryos. The CAB appeared at the 8-cell stage and persisted until the middle stage of embryogenesis. The antigen for the phosphorylated histone 3 antibody was localized to the CAB and persisted in the PGC until hatching after the CAB disappeared. MaternalsnailmRNA, which encodes a transcription factor, was co-localized with the antigen for the H3S28p antibody. Furthermore, we found a novel PGC-specific subcellular structure that we call the germ body (GB). This study thus highlights the conserved and non-conserved features of germline development between ascidians and larvaceans. The rapid development and short life cycle (five days) ofO. dioicawould open the way to genetically analyze germ cell development in the future.