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的相对生长不同。尽管我们对如何控制生长了解很多，但当动物达到特定体型时，导致生长停止的机制却知之甚少。任何脊椎动物都不知道生长中的动物如何评估自己的体型，但人们开始了解昆虫。这项研究的目的是扩展最近发现的昆虫感知其身体大小的机制，并调查这些机制是如何导致停止生长的。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，使用了巨型和侏儒遗传菌株，以及身体和翅膀大小不同的物种。翅膀大小的控制包括从体壁肌肉发出的信号，这些信号精确地控制翅膀的长度。这项研究将首次为昆虫如何监测和控制其体型这一难题提供详细的解释。该奖项支持在STEM领域为大学和高中生以及高中教师提供生理研究、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，这些发现是关于昆虫感知自己体型的生理机制，以及这些生理机制是如何导致它们停止生长的。目的1研究控制生长中的幼虫蜕皮到下一阶段大小的机制。这被称为临界重量，它是由不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。这种触发诱发蜕皮激素的分泌，导致蜕皮到下一个更大的阶段。目的2研究评估一龄动物大小的机制，并确定下一次蜕皮是否会停止生长并开始变态。这就是所谓的阈值大小，由肌球蛋白的增加来定义，肌球蛋白是一种来自体壁肌肉的蛋白质，它会导致少年激素的下降，进而引发蜕皮激素分泌的脉冲，从而完全停止生长。目的3调查的机制，翅膀生长到正确的比例，身体的大小。这是一个特殊的问题，因为翅膀直到进食和躯体生长停止后才开始生长。停止生长后的体型也通过肌球蛋白水平来测量，肌球蛋白水平控制蜕皮素分泌的持续时间和水平，控制翅膀中细胞分裂的速度和持续时间，从而使翅膀与体型的比例正确增长。研究生、本科生、高中生和教师将参与研究，在多个层面上为STEM劳动力的发展做出贡献。研究小组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。

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.