Collaborative Research: Structural and Functional Connectivity of Squid Chromatophores

合作研究：鱿鱼色素细胞的结构和功能连接

• 批准号: 1664767
• 负责人: Joshua Rosenthal
• 金额: $ 34.81万
• 依托单位: Marine Biological Laboratory
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1664767&HistoricalAwards=false
• 关键词: Collaborative; Research; Structural; Functional; Connectivity

Squid and their relatives (other cephalopods such as octopuses) have the ability to change skin color with chromatophores, microscopic muscular organs that are under control of the nervous system. All work on the cellular mechanisms of chromatophore control in squid has focused on three related species that inhabit relatively shallow coastal areas that have prominent features like seaweed, rocks and coral on the ocean floor. Skin-color changes in these species are associated with camouflage, signaling between individuals of the same species and threat displays with other species. The deeper open ocean presents a radically different environment that is also inhabited by many squids, primarily of different taxonomic families from the one commonly inhabiting coastal waters. An important open-ocean family includes the Humboldt squid (Dosidicus gigas). There is little light in the ocean at depths inhabited by these squid during daytime, and visual features such as coral and rocks are non-existent. Novel color-change behaviors in Dosidicus include repetitive whole-body "flashing," used for signaling between individuals of this species, and chaotic "flickering" that may underlie camouflage in the open ocean. Although these dynamic behaviors contrast with the more static patterns typical of coastal species, squids of both families employ temporal and spatial patterning to varying degrees. It is therefore likely that basic mechanisms for controlling the chromatophore network are the same in most, if not all, squids. "Vertical" control from the brain to the chromatophore muscles is known in the coastal squids, and may account for most chromatophore-based behaviors in those species, but behaviors like flickering in deeper-water species may be more influenced by processes within the skin itself that permit changes in chromatophores to spread from one to another without directly involving the nervous system. This hypothetical pathway would define a "horizontal" or distributed control system in the periphery that would permit autonomous behavior within the chromatophore network. This issue is the primary significance of the project. Understanding the fundamentals of horizontal control of chromatophores has the potential of being transformative to the field, because the current paradigm is that all control is directly exerted by the brain. Horizontal control is relevant to blood delivery to local tissues by circulatory systems, gut function and nervous system micro-circuits in vertebrates. Therefore, results from this project would also influence understanding of local control more broadly. From a wider perspective, results of this project will provide insight into the interactions of distributed (horizontal) and top-down (vertical) control mechanisms, a subject relevant to the general ability of complex systems to generate non-predictable, emergent phenomena. This concept is of fundamental interest to a broad sector of society, ranging from engineering to economics to politics.An integrated approach will permit testing the hypothesis that control of the chromatophore network in squid involves peripheral mechanisms that are distinct from the neuronal motor-control pathway that descends from the brain. Spontaneous chromatophore activity that is independent of canonical neural control will be isolated by experimental manipulations in coastal loliginid squid (Doryteuthis opalescens), including chronic denervation and pharmacological block of neuronal activity with tetrodotoxin. In addition, a comparative approach will take advantage of an oceanic ommastrephid species, Dosidicus gigas, in which spontaneous, tetrodotoxin-resistant chromatophore activity is extremely prominent. Relevant methods involve molecular transcriptomics, cellular electrophysiology, immunohistochemistry with confocal microscopy and high-resolution electron microscopy. Specific aims are: 1) identify molecular and physiological properties of relevant ion channels and receptors that control excitability in the radial muscle fibers that operate individual chromatophore organs; 2) define structural, molecular and physiological features of coupling mechanisms between muscle fibers of neighboring chromatophores that define an excitatory transmission pathway within the skin; 3) elucidate the inhibitory role in controlling spontaneous chromatophore activity played by serotonin; 4) carry out parallel experiments in Dosidicus, a member of a family of ecologically important squid in which cellular studies of chromatophores have never been carried out. This project will support undergraduate and graduate student training, and includes significant efforts to involve students from groups underrepresented in STEM.

鱿鱼和他们的近亲(章鱼等其他头足类动物)有能力通过色团改变皮肤颜色，色团是神经系统控制下的微小肌肉器官。所有关于鱿鱼色团控制的细胞机制的工作都集中在三个相关物种上，这些物种生活在相对较浅的沿海地区，这些地区具有突出的特征，如海底的海藻、岩石和珊瑚。这些物种的肤色变化与伪装有关，在同一物种的个体之间发出信号，并对其他物种表现出威胁。更深的开阔海洋呈现了一个完全不同的环境，那里也居住着许多鱿鱼，主要是与沿海水域常见的一个不同的分类学家族。一个重要的远洋家族包括洪堡鱿鱼(Dosidicus Gias)。白天，这些鱿鱼栖息的深处几乎没有光线，珊瑚和岩石等视觉特征是不存在的。Dosidicus的新颜色变化行为包括用于在该物种的个体之间发出信号的重复的全身“闪烁”，以及可能在公开海洋中进行伪装的混乱的“闪烁”。尽管这些动态行为与沿海物种典型的静态模式形成对比，但这两个科的鱿鱼都在不同程度上使用了时间和空间模式。因此，控制发色团网络的基本机制很可能在大多数(如果不是全部)鱿鱼中是相同的。从大脑到着色器肌肉的“垂直”控制在沿海鱿鱼中是已知的，这可能解释了这些物种中大多数基于着色器的行为，但像深水物种中的闪烁这样的行为可能更多地受到皮肤内部过程的影响，这些过程允许着色器的变化从一个人传播到另一个人，而不直接涉及神经系统。这条假设的路径将在外围定义一个“水平”或分布式控制系统，允许在色团网络内的自主行为。这个问题是本项目的首要意义所在。理解色团水平控制的基本原理有可能对该领域产生变革，因为目前的范式是所有控制都是由大脑直接施加的。水平控制与脊椎动物的循环系统、肠道功能和神经系统微循环向局部组织输送血液有关。因此，该项目的结果也将影响对更广泛的地方控制的理解。从更广泛的角度来看，该项目的成果将使人们深入了解分布式(水平)和自上而下(垂直)控制机制的相互作用，这一主题与复杂系统产生不可预测的紧急现象的一般能力有关。从工程学到经济学再到政治学，这一概念对社会的广泛领域都有根本意义。一种综合的方法将允许检验这样一种假设，即控制鱿鱼的色素体网络涉及不同于从大脑下来的神经元运动控制路径的外围机制。在沿海乌贼(Doryteuthis Opalescens)中，通过实验操作，包括慢性去神经和用河豚毒素药理阻断神经元活动，将分离出不依赖于规范神经控制的自发色团活动。此外，一种比较的方法将利用海洋奥马斯虫物种，在这种物种中，自发的、对河豚毒素具有抵抗力的发色团活动非常突出。相关方法包括分子转录学、细胞电生理学、免疫组织化学共聚焦显微镜和高分辨电子显微镜。具体目标是：1)确定控制操作单个发色团器官的放射状肌肉纤维中兴奋性的相关离子通道和受体的分子和生理特性；2)确定相邻发色团的肌肉纤维之间耦合机制的结构、分子和生理特征，从而定义皮肤内的兴奋性传递途径；3)阐明5羟色胺在控制自发发色团活动中的抑制作用；4)对Dosidicus进行平行实验，Dosidicus是一种具有重要生态意义的鱿鱼家族的成员，其细胞研究从未在皮肤内进行过。该项目将支持本科生和研究生的培训，并包括让STEM中代表性不足的群体的学生参与进来的重大努力。