RUI: Unraveling the Developmental Genetics that Underlie Anuran Limb Initiation

大多数有胳膊或腿的生物在孵化或出生时，四肢都有很大的功能。因此，这些动物在胚胎发育期间就长出了四肢。肢体如何发育的研究教会了我们很多关于细胞如何相互作用以及发育过程的变化如何导致不同肢体形状的知识。例如，老鼠的腿和蝙蝠的翅膀之间的差异可以追溯到肢体发育的细微变化。令人惊讶的是，在我们的理解中缺失了动物，比如青蛙的蝌蚪，当它们不再是胚胎时，是如何能够长出肢体的。该项目旨在发现蝌蚪身体的哪个部分在其变形之前产生了青蛙的四肢。结合传统的方法和新的遗传工具，这项研究将揭示蝌蚪的哪些细胞产生肢体，以及调节其发育的基因是如何被控制的。这项工作的发现将揭示自然界创造动物四肢的另一种方法。此外，它们将向我们展示根据自然规律在动物生命的不同阶段生长四肢的可能性。最后，这项工作的影响将超越科学发现，因为许多实验将由一所以女性为中心的大学的本科生进行，这些学生研究人员构成了下一代科学家。对脊椎动物肢体的研究提供了对产生附属物的细胞、遗传和分子机制的深刻理解。他们还揭示了四足动物四肢的基本模式是如何通过进化而改变的，从而产生了我们在自然界中观察到的无数的手臂、腿、翅膀和鳍。大多数肢体实验都是在胚胎发育早期就形成肢体的动物身上进行的。然而，一些四足动物，尤其是青蛙，在胚胎模式和分化发生后很好地形成了四肢。令人惊讶的是，我们对两栖动物蝌蚪最初直接肢体形成的过程知之甚少，因为大多数对这些动物的肢体研究都集中在再生上。最近的技术进步使我们能够利用爪蟾来确定蝌蚪是如何在胚胎组织不复存在的情况下长出肢体的。总的来说，这个项目试图通过测试青蛙从多个胚胎起源产生肢体的假设来回答这个问题，并在基因上推迟了典型的四足动物肢体的形成程序。这一假设将通过首先确定胚胎起源和肢体芽的诱导阶段来验证。然后将询问肢体基因增强子，以发现如何控制青蛙肢体的起始。综上所述，这项工作将为四足动物的肢体多样性和可塑性提供更全面的理解。最后，在这里进行的实验将成为开发新技术的前沿，供爪蟾群落以及更广泛地研究肢体的人使用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Most organisms with arms or legs hatch, or are born, with limbs that are largely functional. Accordingly, these animals make their limbs during embryonic development. The study of how limbs develop has taught us much about how cells interact and how changes in developmental processes result in different limb shapes. For example, differences between the leg of a mouse and the wing of a bat can be traced to subtle changes in limb development. Surprisingly missing from our understanding is how animals, such the tadpoles of frogs, are capable of making a limb when they are no longer embryos. This project aims to discover what part of the tadpole body generates the limbs of the frog prior to its metamorphosis. Combining traditional methods with newly available genetic tools this research will reveal what cells in the tadpole generate the limb and how the genes that regulate its development are controlled. The findings from this work will reveal alternative methods by which nature makes the limbs of animals. Further, they will show us the possibilities of growing limbs during different stages of an animal’s life according to the rules of nature. Finally, this work will have impacts beyond scientific discoveries as many of the experiments will be carried out by undergraduates from a woman centered university, student researchers that comprise the next generation of scientists.Studies of the vertebrate limb have provided a deep understanding of the cellular, genetic, and molecular mechanisms that generate an appendage. They have also revealed how the basic pattern of tetrapod limbs can been modified through evolution to give rise to the myriad of arms, legs, wings, and fins we observe in nature. The majority of limb experimentation has been in animals where the limb forms early in embryogenesis. Yet, several tetrapods, most notably frogs, form their limbs well after embryonic patterning and differentiation has occurred. Surprisingly, we know very little about the processes that initially direct limb formation in amphibian tadpoles since most limb research in these animals has focused on regeneration. Recent technological advancements now allow for us to use the frog Xenopus to determine how a tadpole generates a limb when embryonic tissue is no longer present. Overall, this project seeks to answer this question by testing the hypotheses that frogs generate their limbs from multiple embryonic origins and genetically delay the typical tetrapod limb initiation program. This hypothesis will be tested by first determining the embryological origins and induction stage of the limb buds. Then limb gene enhancers will be interrogated to discover how the initiation of frog limbs is controlled. Taken together, this work will provide a fuller understanding of tetrapod limb diversity and plasticity. Finally, the experiments conducted here will be at the forefront of developing new technologies for use by both the Xenopus community as well as those studying the limb more broadly.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.