The Physiological Control of Body Size

身体和附肢的大小和形状是我们识别动物物种的主要特征。不同物种的不同形状是由于身体各部分的相对生长不同所致。虽然关于生长是如何控制的知道得很多，但对于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。任何脊椎动物都不知道成长中的动物是如何评估自己的身体大小的，但昆虫已经开始了解了。这项研究的目标是扩大关于昆虫感知其身体大小的机制的最新发现，并调查这些机制是如何导致生长停止的。该项目还利用巨型和矮型遗传菌株，以及身体和翅膀大小不同的物种，研究昆虫翅膀与身体大小成正确比例增长的机制。对翅膀大小的控制涉及到身体壁肌肉发出的信号，这些信号精确地控制着翅膀长多长。这项研究将首次对昆虫如何监测和控制其身体大小这一难题提供详细的解释。该奖项支持在STEM领域对大学生和高中生以及高中教师进行生理学研究、数据分析和演示方面的培训。该项目基于最近的几项发现来测试假设，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生长停止。目的1研究控制成长中的幼虫蜕皮到下一龄的大小的机制。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增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幼虫。这种触发物会诱导荷尔蒙蜕皮激素的分泌，从而导致下一个更大的幼虫蜕皮。目的2研究评估幼虫大小的机制，并确定下一次蜕皮是否停止生长并启动变态。这被称为阈值大小，它的定义是肌联蛋白的增加，肌联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，进而触发蜕皮激素分泌的脉冲，从而完全停止生长。目的3研究翅膀生长到与身体大小正确比例的机制。这是一个特殊的问题，因为翅膀直到取食和躯体生长停止后才开始生长。停止生长后的身体大小也是通过肌联蛋白水平来衡量的，它控制着蜕皮激素分泌的持续时间和水平，控制着翅膀中细胞分裂的速度和持续时间，从而使翅膀以正确的比例与身体大小成长。研究生和本科生以及高中生和教师将为这项研究做出贡献，为STEM劳动力在多个层面上的发展做出贡献。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。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.