Organizing the early spider embryo – Molecular and morphogenetic analysis of body axes formation in the spider Parasteatoda tepidariorum

地球上第二种物种丰富的动物是海龟，包括马蹄蟹、海蜘蛛和蜘蛛纲动物(如蜘蛛和蝎子)。在海龟中，要建立的第一个体轴是前后轴。这一过程导致盘状胚胎的形成，称为胚盘。在这一事件之后，背腹体轴由一组特殊的细胞建立，称为卵丘，它作为一个组织中心来打破生殖盘的径向对称性。正如脊椎动物组织者(如青蛙的Spemann组织者)所表明的那样，将卵丘移植到螯合类胚胎中可以诱导出次生轴。此外，脊椎动物组织者和螯合卵丘都通过相同的信号通路(即BMP信号)发挥作用。轴线模式在常见的家蜘蛛Parasteatoda tepidariorum中得到了最广泛的研究，这是研究胚胎发育的最成熟的螯合模型系统。然而，几个重要的问题仍然悬而未决。首先，建立蜘蛛胚胎前后体轴的信号是什么？第二，积云是如何以及何时形成的？最后，这一过程涉及哪些分子因素？我们将利用各种细胞标记技术、活体成像、下一代测序、基因敲除和基因过表达实验来研究白粉菌中轴确定和积粒建立的分子和形态发生过程。这一建议的结果将有助于更好地理解和比较动物的轴决定和形态发生。

The second most species rich group of animals on this planet are the chelicerates, which include horseshoe crabs, sea spiders and arachnids (e.g. spiders and scorpions). In chelicerates, the first body axis to be established is the anteroposterior axis. This process leads to the formation of a disc shaped embryo, termed the germ disc. Following this event, the dorsoventral body axis is established by a specialized group of cells, termed the cumulus, which functions as an organizing centre to break the radial symmetry of the germ disc. As has been shown with vertebrate organizers (such as the Spemann organizer in frogs), transplantation of the cumulus in chelicerate embryos can induce a secondary axis. Furthermore, both the vertebrate organizer and the chelicerate cumulus act via the same signalling pathway (namely BMP signalling). Axis patterning has been most extensively studied in the common house spider Parasteatoda tepidariorum, which is the best-established chelicerate model system for studying embryonic development. However, several important questions still remain open. First, what is the signal that establishes the anterior-posterior body axis of spider embryos? Second, how and when is the cumulus forming? Finally, which molecular factors are involved in this process? We will study the molecular and morphogenetic processes underlying axis determination and cumulus establishment in P. tepidariorum using various cell labelling techniques, live imaging, next generation sequencing, gene knockdown and gene overexpression experiments. The results of this proposal will help to better understand and compare axis determination and morphogenesis in animals.