Dorsoventral axis formation in the cricket Gryllus bimaculatus as example of convergent evolution of Toll’s morphogen function

蟋蟀双斑蟋蟀背腹轴的形成作为托尔形态发生素功能趋同进化的例子

• 批准号: 516937640
• 负责人: Professor Dr. Siegfried Roth
• 金额: --
• 依托单位: Institut für Entwicklungsbiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/516937640?language=en
• 关键词: Dorsoventral; axis; formation; cricket; Gryllus

Toll and BMP signaling are essential for dorsoventral (DV) axis formation in all insects studied so far. The Toll signaling gradient in Drosophila represents moreover, one of the best-understood morphogen systems determining cell fates in a concentration-dependent manner. While BMP is crucial for the establishment of the DV axis in most bilaterian animals, Toll’s DV function appears to be an evolutionary novelty of insects. In the past we have studied DV axis formation in representatives of major insect lineages and found a diminishing requirement for Toll in insects more distantly related to Drosophila. Concomitantly, the importance of BMP signaling increases approaching the BMP dominated patterning networks known from other bilateria. Surprisingly, the cricket, Gryllus bimaculatus, an orthopteran species representing the basal-most insect lineage we have studied so far, did not conform to this trend. The Gryllus DV system rather has striking similarities to that of Drosophila. In this proposal, we want to unravel molecular mechanisms of Gryllus DV pattering and thereby explore the possibility of convergent evolution of Toll’s morphogen function. Our work programme is based on recent advances in Gryllus live-imaging, transgenesis, CRISPR/Cas9 mediated genome editing and genome sequencing, and it encompasses four specific objectives. We plan (1) to study the spatiotemporal profile of Toll signaling by visualizing the nuclear accumulation of the transcription factor Dorsal/NF-κB, (2) to identify Toll and BMP target genes by differential transcriptome analysis, (3) to characterize cis-regulatory elements of target genes by ATAC-seq, computational motif searches and ATAC-seq based footprinting, (4) to tag target genes for live imaging and perform reporter assays to confirm the functionality of predicted cis-regulatory elements. Together, these data will provide molecular insights into the unexpected parallels between fly and cricket DV patterning and complement our picture of the complex evolutionary history of DV axis formation in insects.

到目前为止所研究的所有昆虫中，Toll和BMP信号对于背腹侧（DV）轴的形成至关重要。此外，果蝇的Toll信号梯度代表了一种以浓度依赖的方式决定细胞命运的最容易理解的形态原系统。虽然BMP对大多数双边动物的DV轴的建立至关重要，但托尔的DV功能似乎是昆虫进化的新事物。在过去，我们研究了主要昆虫谱系中DV轴的形成，发现与果蝇亲缘关系较远的昆虫对Toll的需求减少。同时，BMP信号的重要性增加，接近BMP主导的模式网络，从其他双侧已知。令人惊讶的是，蟋蟀（Gryllus bimaculatus），一种代表我们迄今为止研究过的最基础昆虫谱系的直足动物，却不符合这种趋势。Gryllus DV系统与果蝇有着惊人的相似之处。在本研究中，我们希望揭示Gryllus DV模式的分子机制，从而探索Toll形态因子功能趋同进化的可能性。我们的工作计划基于Gryllus实时成像、转基因、CRISPR/Cas9介导的基因组编辑和基因组测序的最新进展，包括四个具体目标。我们计划(1)通过可视化转录因子Dorsal/NF-κB的核积累来研究Toll信号的时空分布，(2)通过差异转录组分析鉴定Toll和BMP靶基因，(3)通过ATAC-seq、计算基序搜索和基于ATAC-seq的足迹分析来表征靶基因的顺式调控元件。(4)标记目标基因进行实时成像，并进行报告基因检测，以确认预测的顺式调控元件的功能。总之，这些数据将为苍蝇和蟋蟀DV模式之间意想不到的相似之处提供分子见解，并补充我们对昆虫DV轴形成的复杂进化史的了解。