Early patterning of the spider embryo: a cluster of mesenchymal cells at the cumulus produces Dpp signals received by germ disc epithelial cells
Early patterning of the spider embryo: a cluster of mesenchymal cells at the cumulus produces Dpp signals received by germ disc epithelial cells
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DOI：
10.1242/dev.00390
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发表时间：
2003-05-01
期刊：
影响因子：
4.6
通讯作者：
Oda, H
中科院分区：
文献类型：
--
作者：
Akiyama-Oda, Y;Oda, H
在蜘蛛的早期胚胎发生中，卵丘的特征是从胚盘中心开始向离心方向运动的细胞增厚。这种积云运动打破了胚盘形态的径向对称性，与胚胎背侧区域的发育相关。对蜘蛛胚胎的经典实验表明，当异位移植时，卵丘具有诱导第二轴的能力。在这项研究中，我们已经研究了家蜘蛛，Achaearanea tepidariorum，知识的基础上，从果蝇的特征积云在细胞和分子水平。在卵丘中，一簇约10个间充质细胞，称为卵丘间充质（CM）细胞，位于上皮细胞下方，其中CM细胞迁移到生殖盘的边缘。迁移的CM细胞附近的胚盘上皮细胞将细胞丝样突起从其基底侧延伸到CM细胞的表面。分子克隆和整体安装原位杂交表明，CM细胞表达的蜘蛛同源果蝇decapentaplegic（DPP），它编码的分泌蛋白，作为一个背部形态在果蝇胚胎的功能。此外，蜘蛛Dpp信号似乎诱导梯度水平的磷酸化的母亲对dpp（Mad）蛋白质在生殖盘上皮细胞的细胞核。添加数据从蜘蛛同系物的叉头，orthodenticle和尾部，我们建议，在相反的果蝇胚胎，渐进mesenchymalepithelial细胞的相互作用，涉及Dpp-Mad信号级联产生背腹极性按照前后轴形成在蜘蛛胚胎。我们的研究结果支持的想法，卵丘中起着核心作用的轴向图案形成的蜘蛛胚胎。
In early embryogenesis of spiders, the cumulus is characteristically observed as a cellular thickening that arises from the center of the germ disc and moves centrifugally. This cumulus movement breaks the radial symmetry of the germ disc morphology, correlating with the development of the dorsal region of the embryo. Classical experiments on spider embryos have shown that a cumulus has the capacity to induce a secondary axis when transplanted ectopically. In this study, we have examined the house spider, Achaearanea tepidariorum, on the basis of knowledge from Drosophila to characterize the cumulus at the cellular and molecular level. In the cumulus, a cluster of about 10 mesenchymal cells, designated the cumulus mesenchymal (CM) cells, is situated beneath the epithelium, where the CM cells migrate to the rim of the germ disc. Germ disc epithelial cells near the migrating CM cells extend cytoneme-like projections from their basal side onto the surface of the CM cells. Molecular cloning and whole-mount in situ hybridization showed that the CM cells expressed a spider homolog of Drosophila decapentaplegic (dpp), which encodes a secreted protein that functions as a dorsal morphogen in the Drosophila embryo. Furthermore, the spider Dpp signal appeared to induce graded levels of the phosphorylated Mothers against dpp (Mad) protein in the nuclei of germ disc epithelial cells. Adding data from spider homologs of fork head, orthodenticle and caudal, we suggest that, in contrast to the Drosophila embryo, the progressive mesenchymalepithelial cell interactions involving the Dpp-Mad signaling cascade generate dorsoventral polarity in accordance with the anteroposterior axis formation in the spider embryo. Our findings support the idea that the cumulus plays a central role in the axial pattern formation of the spider embryo.