RUI: Investigating tardigrade development to unravel the evolution of animal body plans

RUI：研究缓步动物的发育以揭示动物身体计划的进化

• 批准号: 1951257
• 负责人: Frank Smith
• 金额: $ 33.24万
• 依托单位: University of North Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-01 至 2024-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1951257&HistoricalAwards=false
• 关键词: RUI; Investigating; tardigrade; development; unravel

The evolution of animal body plans has traditionally been difficult to study because their origins lie in an ancient period for which fossils are extremely rare. Recent advances in developmental biology and genomics techniques now provide alternative methods to reconstruct the evolutionary steps that gave rise to animal body plans. Studies of water bear (Tardigrade) development may be especially informative for investigating two important themes of body plan evolution—segmentation and miniaturization. Segmentation is a common characteristic of animals. This project will investigate tardigrade development in order to reconstruct the evolutionary steps that underlie the origins of the segmentation mechanisms that are present in modern animals. Miniaturization has evolved independently in several animal lineages, including in the tardigrade lineage, but very little is known about the developmental underpinnings of miniaturization. This project aims to identify the developmental origins of the compact tardigrade body plan, and to determine the consequences of miniaturization on the developmental mechanisms that control development of the tardigrade gut. Results of this work may reveal general developmental principles that underlie miniaturization. This project will provide training to eleven undergraduate students. A key aim is to provide training to students from underrepresented groups in biology. Research on tardigrades also provides an excellent opportunity to foster public science outreach. This project uses research activities to enhance public science literacy in Jacksonville, FL. A recent study of Hox genes revealed that the tardigrade body plan evolved by the loss of mid-trunk segments. This result raises several questions. (1) What is the developmental basis for the loss of mid-trunk segments? In many bilaterians, before growth of a mid-trunk region, antagonistic interactions between the canonical Wnt signaling pathway and inhibitors of this pathway specify anterior and posterior regions of the body axis. This work will test whether this mechanism specifies the entire body axis of a tardigrade, as predicted if tardigrades simply lost the ability to grow a mid-trunk region. (2) Do the remaining segments in tardigrades develop by the same segmentation mechanisms that have been identified in arthropods? To address this question, experiments will test whether the segment polarity gene network that specifies segment boundaries in arthropods also specifies segment boundaries in tardigrades. Results of this study will illuminate where in panarthropod phylogeny this network evolved a role in specifying segment boundaries. (3) What was the impact of the loss of mid-trunk segments on the gut, an unsegmented part of the body axis? To address this question, this work will determine the extent to which mechanisms that pattern the gut during development in other bilaterians have diverged in tardigrades. Experiments will utilize RNA interference to disrupt gene function and situ hybridization to characterize gene expression patterns during development of the tardigrade Hypsibius exemplaris. This research will provide insight into developmental underpinnings of the evolution of segmentation and secondary simplification.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

动物体型的演化传统上很难研究，因为它们的起源是在一个化石极其罕见的古代时期。发育生物学和基因组学技术的最新进展现在提供了替代方法来重建导致动物身体计划的进化步骤。对水熊虫发育的研究对于探讨体平面进化的两个重要主题--分割和小型化可能提供特别的信息。分割是动物的共同特征。 该项目将研究缓步动物的发育，以重建现代动物中存在的分割机制起源的进化步骤。小型化在几个动物谱系中独立进化，包括缓步动物谱系，但对小型化的发展基础知之甚少。该项目旨在确定紧凑的缓步动物身体计划的发展起源，并确定控制缓步动物肠道发展的发展机制的小型化的后果。这项工作的结果可能会揭示一般的发展原则，微型化的基础。该项目将为11名本科生提供培训。一个关键目标是为来自生物学领域代表性不足群体的学生提供培训。对缓步动物的研究也为促进公共科学宣传提供了一个极好的机会。该项目利用研究活动，以提高公众的科学素养在杰克逊维尔，佛罗里达州。最近的一项研究Hox基因显示，缓步动物的身体计划演变的损失中躯干部分。这一结果提出了几个问题。(1)躯干中段缺失的发育基础是什么？在许多双侧性动物中，在躯干中部区域生长之前，经典Wnt信号通路和该通路的抑制剂之间的拮抗性相互作用指定体轴的前部和后部区域。这项工作将测试这种机制是否指定了缓步动物的整个身体轴，正如预测的那样，如果缓步动物只是失去了生长中间躯干区域的能力。(2)在缓步动物中的其余部分是否是通过与节肢动物中相同的分割机制发展的？为了解决这个问题，实验将测试是否节极性基因网络，规定节的节肢动物的边界也规定节的界限在缓步动物。本研究的结果将阐明在泛节肢动物的进化，这个网络在指定段边界的作用。(3)躯干中段的缺失对肠道有什么影响？肠道是身体轴上未分割的部分。为了解决这个问题，这项工作将确定在何种程度上的机制，模式的肠道在发展过程中，在其他bilaterians已经分歧缓步动物。实验将利用RNA干扰破坏基因功能和原位杂交来表征缓步类Hypsibius exemplaris发育过程中的基因表达模式。这项研究将提供深入了解发展的基础上的演变分割和二级简化。这个奖项反映了NSF的法定使命，并已被认为是值得支持，通过评估使用基金会的智力价值和更广泛的影响审查标准。