The Physiological Control of Body Size

身体和附属物的大小和形状是我们识别动物种类的主要特征。不同物种的不同形状是由于身体部位相对生长的差异。尽管人们对生长是如何控制的了解很多，但对当动物达到特定物种的大小时导致生长停止的机制却知之甚少。生长中的动物如何评估自己的身体大小，这在任何脊椎动物中都不为人所知，但在昆虫中开始被理解。这项研究的目的是扩大最近发现的昆虫感知自己身体大小的机制，并研究这些机制如何导致停止生长。该项目还研究了昆虫翅膀与身体大小成正确比例生长的机制，使用巨大和矮小的遗传菌株，以及身体和翅膀大小不同的物种。翅膀大小的控制涉及到从体壁肌肉发出的信号，这些肌肉精确地控制着翅膀的生长时间。这项研究将首次详细解释昆虫如何监测和控制其身体大小的难题。该奖项支持大学和高中学生以及STEM领域的高中教师在生理研究，数据分析和演示方面的培训。该项目测试了基于最近几项发现的假设，这些发现涉及昆虫感知其身体大小的生理机制，以及这些机制如何导致停止生长。目的1研究控制生长期幼虫蜕皮至下一龄期的大小的机制。这被称为临界重量，它是由非生长的气管系统定义的，当它不再能够为不断生长的身体提供足够的氧气时，它会触发蜕皮到下一个更大的龄期。这个触发器诱导激素蜕皮激素的分泌，这导致蜕皮到下一个更大的龄期。目的2探讨评估一个龄期大小的机制，并确定下一次蜕皮是否停止生长并开始变态。这被称为阈值大小，它是由肌球蛋白的上升定义的，肌球蛋白是一种来自体壁肌肉的蛋白质，它会导致保幼激素的下降，这反过来又会触发蜕皮激素分泌的脉冲，完全停止生长。目的3研究翅膀生长到与身体大小成正确比例的机制。这是一个特殊的问题，因为翅膀开始生长，直到喂养和躯体生长已经停止。生长停止后的身体大小也通过肌球蛋白水平来测量，肌球蛋白水平控制蜕皮激素分泌的持续时间和水平，控制翅膀中细胞分裂的速率和持续时间，使得翅膀与身体大小成正确的比例生长。研究生和本科生以及高中学生和教师将为研究做出贡献，为多层次的STEM劳动力发展做出贡献。该研究团队还将为当地儿童博物馆的公共教育活动做出贡献。该奖项反映了NSF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。

The sizes and shapes of bodies and appendages are the primary characteristics by which we recognize species of animals. The different shapes of different species are due to differences in the relative growth of body parts. Although much is known about how growth is controlled, little is known about the mechanisms that cause growth to stop when an animal reaches a species-specific size. How a growing animal assesses its body size is not known for any vertebrate, but is beginning to be understood in insects. The goal of the research is to expand upon recent discoveries about the mechanisms by which insects sense their body size, and to investigate how those lead to the cessation of growth. The project also investigates the mechanism by which insect wings grow in correct proportion to body size, using giant and dwarf genetic strains, as well as species that differ in body and wing size. The control of wing size involves signals emanating from the body wall muscles that control precisely for how long wings grow. This research will, for the first time, provide a detailed explanation of the difficult problem of how insects monitor and control their body size. The award supports training for college and high school students, as well as high school teachers in STEM fields, in physiological research, data analysis and presentation. The project tests hypotheses based on several recent discoveries about the physiological mechanisms by which insects sense their body size, and how those lead to the cessation of growth. Aim 1 investigates the mechanism that controls the size at which a growing larva molts to the next instar. This is called the critical weight, which is defined by the non-growing tracheal system that triggers the molt to the next larger instar when it is no longer able to supply sufficient oxygen to the ever-growing body. This trigger induces the secretion of the hormone ecdysone, which causes a molt to the next larger instar. Aim 2 investigates the mechanism that assesses the size of an instar and determines whether the next molt stops growth and initiates metamorphosis. This is called the threshold size, which is defined by the rise in myoglianin, a protein from muscles of the body wall, that causes the decline of juvenile hormone, that, in turn, triggers a pulse of ecdysone secretion, stopping growth altogether. Aim 3 investigates the mechanism by which wings grow to the correct proportion to body size. This is a special problem because wings do not begin to grow until after feeding and somatic growth have stopped. Body size after growth stops is also measured by myoglianin levels, which control the duration and level of ecdysone secretion, controlling the rate and duration of cell division in the wing so that the wing grows in correct proportion to body size. Graduate and undergraduate students and high school students and teachers will contribute to the research, contributing to STEM workforce development at multiple levels. The research team will also contribute to public education activities at local children’s museums.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.