DISSERTATION RESEARCH: Effect of Body Size and Development on Gas Exchange Mechanisms in Insects: Diffusion vs. Convection

论文研究：身体大小和发育对昆虫气体交换机制的影响：扩散与对流

• 批准号: 0206678
• 负责人: Jon Harrison
• 金额: $ 1万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-06-01 至 2003-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0206678&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Effect; Body; Size

DISSERTATION RESEAERCH: Effect of Body Size and Development on Gas Exchange Mechanisms in Insects: Diffusion vs. ConvectionJon F. HarrisonKendra J. GreenleeDelivery of oxygen in organisms occurs by two basic mechanisms, convection and diffusion. Determining the relative importance of these mechanisms is fundamental to understanding gas exchange in any organism. Convection occurs when pressure generated by respiratory muscles causes bulk movement of air. Diffusion occurs by passive movement of oxygen molecules from areas of high concentration to areas of lower concentration. For insects, the relative role of convection and diffusion in gas exchange is highly controversial. Past evidence supports the notion that some insects can sustain their energy demands through diffusion of oxygen alone. However, many insects exhibit pressure-generating behaviors, such as abdominal pumping in grasshoppers. In particular, it is thought that the relative importance of convection may increase with insect body size. In this study, the relative importance of diffusion and convection to insect gas exchange will be quantified by manipulating the ability of oxygen to diffuse using different carrier gases. Generally, air contains 21% oxygen and 79% nitrogen. Substituting helium or sulfur hexaflouride for nitrogen alters the oxygen diffusion coefficient, making it easier or more difficult, respectively, for oxygen to move by diffusion. The grasshoppers' metabolic response to lowered oxygen levels will be measured in all three carrier gases. If grasshoppers are breathing by diffusion, their metabolic responses should be strongly affected by these manipulations. Conversely, if grasshoppers breathe by convection, their metabolic responses to hypoxia will not be affected by variations in carrier gas. To test whether the relative importance of diffusion and convection varies with size, these experiments will be performed with juvenile (small) and adult (large) grasshoppers. To further test the importance of diffusion and convection in insects, grasshoppers will be anesthetized with ketamine to prevent abdominal pumping movements. If convection does become increasingly important in larger insects, ketamine is predicted to have a much stronger effect on metabolic responses to hypoxia in larger grasshoppers. Together, these experiments will provide the first empirical tests of the relative importance of diffusion and convection in insects of different sizes.

论文回合：体大小和发育对昆虫气体交换机制的影响：扩散与对流jon F. Harrisonkendra J.氧气在生物体中的氧气中氧气的氧气递送通过两种基本机制，对流和扩散发生。 确定这些机制的相对重要性对于理解任何生物体的气体交换至关重要。 当呼吸道肌肉产生的压力导致空气的大部分运动时，就会发生对流。 扩散是通过从高浓度到较低浓度区域的被动运动来进行的。 对于昆虫，对流和扩散在气体交换中的相对作用是有争议的。 过去的证据支持这样的观念，即某些昆虫可以单独扩散氧气可以维持其能量需求。 然而，许多昆虫表现出压力产生的行为，例如蚱hoppers中的腹部抽水。 特别是，人们认为对流的相对重要性可能随昆虫体大小而增加。 在这项研究中，通过操纵氧气使用不同的载气体扩散的能力来量化扩散和对流与昆虫气体交换的相对重要性。 通常，空气含有21％的氧气和79％的氮。 代替氦或硫六氟化物代替氮，改变了氧扩散系数，使氧气通过扩散而分别更容易或更困难。 蚱hoppers对降低氧气水平的代谢反应将在所有三种载体中测量。 如果蚱hoppers通过扩散呼吸，它们的代谢反应应受这些操纵的强烈影响。 相反，如果蚱hoppers通过对流呼吸，它们对缺氧的代谢反应不会受到载气的变化的影响。 为了测试扩散和对流的相对重要性是否随尺寸而变化，这些实验将使用少年（小）和成人（大）蚱hops进行。 为了进一步测试昆虫中扩散和对流的重要性，将用氯胺酮麻醉蚱hoppers，以防止腹部抽水运动。 如果对流在较大的昆虫中确实变得越来越重要，则预计氯胺酮对较大蚱hopper的缺氧的代谢反应具有更强的作用。 总之，这些实验将提供第一个经验检验，以实现不同大小昆虫的扩散和对流的相对重要性。