Steroid-mediated Chromatin Remodeling in Developmental Plasticity

发育可塑性是生物体根据外界因素改变自身发育的能力。这很重要，因为它使植物和动物能够适应不断变化的环境条件。发育可塑性是一种重要而广泛的现象，然而，对于外部信息如何转化为有机体发育变化的机制基础，人们的理解有限。在某些情况下，我们很清楚动物是如何通过产生激素来对环境线索做出反应的，以及这些激素信号是如何转化为发育变化的。然而，鲜为人知的是，这些环境诱导的激素信号是如何转化为特定组织的发育变化的。在这项工作中，研究人员将以七叶蝶为模型，研究环境线索如何通过DNA结构的大规模改变来协调基因表达的组织特异性变化。七叶蝶作为研究可塑性的一个强大的模型系统，因为不同的种群对季节线索的反应不同，从而允许分离控制和调节自然种群可塑性的遗传元素。这项工作的发现将有助于对环境线索如何通过DNA结构的大规模修饰诱导发育变化有新的认识。这些知识构成了预测生物体对变化环境的反应的基础。对本科生和研究生进行遗传和发育科学现代生物学研究方面的培训是该项目不可或缺的一部分。这包括招募科学界代表性不足的群体的成员。在发育过程中，表型可塑性可分为三部分。首先，生物体感知到营养、温度、光周期、拥挤或捕食者存在等线索，然后将其转化为内部信号，这在自然界中通常是内分泌信号。其次，整个生物体的细胞接收信号的方式通常看起来是组织特异性的。第三，细胞内的分子机制处理和响应信号，导致基因调控的变化，从而改变发育。虽然表型可塑性的生理基础已经在许多系统中得到了很好的描述，但直到最近几年，研究才开始关注发育如何响应可塑性诱导的生理信号的分子和遗传机制。这个问题特别引人注目，因为不同的组织对信号的反应不同，不同组织的反应模式和程度在几代之间会迅速变化。然而，目前尚不清楚环境诱导的内分泌信号如何快速调节组织特异性塑料表型。通过这项工作，Reed和他的同事将研究内分泌信号和染色质组织如何相互作用以诱导七叶蝶的季节性发育可塑性。具有良好特征的内分泌信号，季节性反应规范中的自然遗传变异，以及应用实验方法（包括ATAC-seq和CRISPR基因组编辑）的能力，使该物种成为解决内分泌信号如何介导全基因组染色质重塑以及染色质重塑如何诱导组织特异性塑性表型的理想模型。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。

Developmental plasticity is the ability of an organism to alter its development in response to external cues. This is significant because it allows plants and animals to adapt to changing environmental conditions. Developmental plasticity is an important and widespread phenomenon, however there is only limited understanding of the mechanistic basis of how external information is translated into changes in organismal development. In some cases, it is well understood how animals respond to environmental cues through production of hormones, and how these hormone signals are translated into developmental changes. What is less known, however, is how these environmentally induced hormone signals are translated into developmental changes in specific tissues. With this work, the investigators will use buckeye butterflies as a model to examine how environmental cues can coordinate tissue-specific changes in gene expression through the large-scale alteration of DNA structure. The buckeye butterfly serves as a powerful model system for studying plasticity because different populations show variation in their responses to seasonal cues, thus allowing isolation of genetic elements that control and tune plasticity in natural populations. Findings from this work will help in developing a new understanding of how environmental cues can induce developmental changes through large-scale modification of DNA structure. Such knowledge forms the basis for predicting organismal response to changing environments. Training of undergraduate and graduate students in modern biological investigations of genetic and developmental science is integral to the project. This includes the recruitment of members of under-represented groups in science. Developmentally, phenotypic plasticity can be characterized as a three-part process. First, a cue such as nutrition, temperature, photoperiod, crowding, or predator presence, is sensed by the organism and then translated into an internal signal, which is often endocrine in nature. Second, cells throughout the organism receive the signal in a manner that often appears to be tissue-specific. Third, molecular machinery within cells processes and responds to the signal, resulting in changes in gene regulation, thus altering development. While the physiological basis of phenotypic plasticity has been well described in many systems, it is only in recent years that studies have started to look at the molecular and genetic mechanisms of how development responds to plasticity-inducing physiological signals. This question is particularly compelling because different tissues respond differently to signals, and the mode and degree of response of different tissues can change quickly between generations. However, it is still unclear how tissue-specific plastic phenotypes can be rapidly modulated by environmentally induced endocrine signals. With this work Reed and colleagues will study how endocrine signaling and chromatin organization interact to induce seasonal developmental plasticity in the buckeye butterfly Junonia coenia. A well-characterized endocrine signal, natural genetic variation in seasonal reaction norms, and the ability to apply experimental approaches including ATAC-seq and CRISPR genome editing makes this species an ideal model to address how endocrine signaling mediates genome-wide chromatin remodeling, and how chromatin remodeling induces tissue-specific plastic phenotypes.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.