Collaborative Research: RUI: Diversity of modulation and functional flexibility in small neuronal networks: An evolutionary and mechanistic approach

有节奏的运动，如心跳和运动，必须是灵活的，以允许动物改变他们的行为，以应对不断变化的环境。有节奏的运动是由神经细胞网络控制的，这些神经细胞相互作用，产生驱动适当肌肉运动的神经冲动模式。为了改变运动模式，这些神经网络依赖于被称为神经调节剂的化合物的作用；这些化合物改变（调节）网络中细胞的性质和相互作用，从而使它们能够改变由网络产生的运动模式。这些变化包括，例如，导致行为速度的变化或控制运动模式不同部分的肌肉协调的变化。然而，有证据表明，类似网络可以改变的程度（“调节能力”）因物种而异。该项目解决了与调制能力的可变性相关的两个基本问题：首先，在进化的时间尺度上，哪些变量决定了网络可以被调制的程度，其次，哪些因素/机制是调制能力差异的基础。除了以只吃海带的螃蟹与吃多种食物的螃蟹的口胃网络和心脏网络为例来解决这些问题外，当前的项目还通过以下方式为下一代科学家做准备：(1)培训高中生和本科生各种研究技术，以及设计实验和分析和呈现数据；(2)为缅因州七年级印第安人参与科学项目的神经科学部分提供连续性和潜在扩展，以提高他们在高中及以后的教育愿望和成功。本项目利用具有巨大饮食多样性的密切相关的主要螃蟹物种的口胃和心脏网络来验证调节能力是任何给定行为多样性的重要进化基础的假设，并询问调节能力差异的机制。目前的数据表明，Pugettia producta（一种只吃海带的物种）的口胃网络对许多改变另一种主要物种（libia emarginata）的口胃网络的调节剂没有反应，而另一种主要物种有高度多样化的饮食。该项目扩大了测试的神经调节剂的数量，并检查和比较了同一物种的心脏网络的调节。研究人员使用转录组学和质谱法鉴定了这些巨噬细胞中肽调节剂的天然同型异构体，然后使用生理记录来比较普吉蒂亚人和利比尼亚人口胃和心脏神经肌肉系统的调节能力。预测是，普吉提亚口胃系统的调节能力比机会取食动物的调节能力小，但在可能对灵活性有类似需求的系统中，例如心脏神经肌肉系统的调节能力并没有明显不同。为了检查调节能力变化的机制，研究人员使用转录组学来验证Pugettia口胃系统调节能力下降的机制是这些调节剂受体的缺失或丰度降低的假设。转录组学结果通过qRT-PCR和通过两种受体的表达来比较相对结合亲和力来证实。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。

Rhythmic movements, such as heartbeat and locomotion, must be flexible to allow animals to alter their behavior in response to changing conditions. Rhythmic movements are controlled by networks of nerve cells that interact with one another to produce patterns of nerve impulses that drive appropriate muscle movements. To alter movement patterns, these neural networks rely on the actions of chemical compounds called neuromodulators; these compounds alter (modulate) the properties and interactions of the cells in the network, thereby enabling them to alter the pattern of movements that are generated by the network. Such alterations include, for example, changes in the speed of the resulting behavior or the coordination of muscles that control different portions of the movement pattern. There is evidence, however, that the extent to which similar networks can be altered ("modulatory capacity") varies among species. This project addresses two fundamental questions related to this variability in modulatory capacity: first, on an evolutionary timescale, what variables determine the extent to which networks can be modulated, and second, what factors/mechanisms underlie differences in modulatory capacity. In addition to addressing these questions using as exemplars the stomatogastric network and the cardiac network in a crab that eats only kelp versus a crab that eats many different kinds of food, the current project also prepares the next generation of scientists by (1) training high school students and undergraduates in a variety of research techniques, as well as in designing experiments and in analyzing and presenting data, and (2) providing continuity and potential expansion of the neuroscience component of a program that engages 7th grade Native Americans in Maine in science to enhance their educational aspirations and success in high school and beyond.This project uses the stomatogastric and cardiac networks of closely related majoid crab species with vastly different dietary diversity to test the hypothesis that modulatory capacity is an important evolutionary substrate for diversity within any given behavior, and to ask what mechanisms underlie differences in modulatory capacity. Current data suggest that the stomatogastric network in Pugettia producta, a species that eats only kelp, is not responsive to many modulators that alter the network in another majoid, Libinia emarginata, which has a highly diverse diet. This project expands the number of neuromodulators tested, as well as examines and compares modulation of the cardiac network in the same species. The investigators use transcriptomics and mass spectrometry to identify native isoforms of peptide modulators in these majoids, then use physiological recordings to compare the modulatory capacities of the Pugettia and Libinia stomatogastric and cardiac neuromuscular systems. The prediction is that modulatory capacity in the Pugettia stomatogastric system is less than that of the opportunistic feeder, but that modulation in systems that are presumably subject to similar demands for flexibility, e.g., the cardiac neuromuscular system, is not markedly different. To examine the mechanisms that underlie changes in modulatory capacity, the investigators use transcriptomics, testing the hypothesis that the mechanism underlying decreased modulatory capacity of the Pugettia stomatogastric system is an absence or decreased abundance of receptors to those modulators. Transcriptomics results are confirmed using qRT-PCR and through expression of the receptors of the two species to compare relative binding affinities.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.