From water-breathing nymphs to air-breathing adults: Insects as a model system to investigate the physiological challenges associated with the transition of life from water to land

从呼吸水的若虫到呼吸空气的成虫：昆虫作为模型系统来研究与生命从水到陆地的转变相关的生理挑战

• 批准号: RGPIN-2014-05794
• 负责人: Matthews, Philip
• 金额: $ 2.84万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=659055
• 关键词: water; breathing; nymphs; air; adults

This Discovery Program will take the novel approach of using aquatic insects to examine the physiological challenges associated with the transition from breathing water to breathing air. Aquatic insects support valuable freshwater ecosystems and fisheries, but are highly susceptible to changes in water quality, so understanding their physiology is of crucial importance for successful environmental management. Our current understanding of the respiratory challenges associated with moving between water and air comes from studying how aquatic animals, particularly vertebrates, have adapted their morphology and physiology to function on land. From this perspective, water-breathing is the ancestral condition and air-breathing is a derived state. The insects, however, have performed this feat in reverse, adapting their terrestrial air-breathing physiology to function in water. Although all adult insects are air-breathers, representatives of nine insect orders have evolved to be developmentally amphibious, spending the juvenile proportion of their life cycle as aquatic nymphs or larvae that possess gills and breathe water. These insect groups provide an exceptional opportunity to examine the evolution of adaptations associated with aquatic respiration, and to determine whether environmental constraints have caused gill-bearing insects to converge on a respiratory physiology comparable to other aquatic animals, or whether the phylogenetic constraints of their terrestrial ancestry have resulted in a respiratory physiology similar to air-breathing animals. The physiological consequences of the insects' return to water are not well understood, but there is tantalizing evidence that water-breathing nymphs possess elevated internal CO2 levels commonly associated with breathing air, an observation that cannot be explained by current textbook dogma. Furthermore, we know nothing of the mechanisms and physiological shifts that enable these insects, during metamorphosis, to change rapidly from breathing with gills to using an air-filled respiratory system. My research program aims to identify and compare the respiratory and acid-base strategies used by water-breathing juvenile insects with those of the air-breathing adults, and to explore the physiological changes that occur during their rapid transition from water to land. I will use a range of techniques, including respirometry, morphometry and histology, to reveal the different strategies used by the aquatic and terrestrial life stages to regulate their internal oxygen and carbon dioxide levels, and their acid-base balance. Thus, this research program addresses a fundamental gap in our understanding of insect physiology and provides insight into the evolution of respiratory adaptations underlying the transition from water to land.

该发现计划将采用使用水生昆虫来检查与从呼吸水到呼吸空气的过渡相关的生理挑战的新方法。水生昆虫支持有价值的淡水生态系统和渔业，但非常容易受到水质变化的影响，因此了解其生理学对于成功的环境管理至关重要。我们目前对与水和空气之间移动相关的呼吸挑战的理解来自研究水生动物，尤其是脊椎动物，使其形态和生理学如何在陆地上起作用。从这个角度来看，水的呼吸是祖先的条件，空气呼吸是一个衍生状态。然而，昆虫以相反的形式进行了这一壮举，使它们的陆地呼吸生理学适应在水中的功能。尽管所有成年昆虫都是空气呼吸的，但九种昆虫秩序的代表已经发展为发育性的两栖动物，将其生命周期的少年比例作为水生若虫或幼虫，具有g和呼吸水。这些昆虫群提供了一个非凡的机会，可以检查与水生呼吸相关的适应性演变，并确定环境限制是否导致含g的昆虫在与其他水生动物相当的呼吸生理学上融合，或者是否在呼吸道生理学的呼吸道生理学的生理祖先类似于与空气生理学相似的呼吸生物学的生理约束。昆虫返回水的生理后果尚不清楚，但是有诱人的证据表明，水呼吸若虫具有升高的内部二氧化碳水平，通常与呼吸空气相关，这一观察结果无法通过当前的教科书教义来解释。此外，我们对使这些昆虫的机制和生理转移一无所知，使这些昆虫能够在变态过程中迅速从gal呼变为使用充气呼吸系统的呼吸。我的研究计划旨在识别和比较呼吸呼吸的少年昆虫使用的呼吸道和酸碱策略与空气呼吸的成年人的呼吸道和酸碱策略，并探索从水到陆地快速过渡期间发生的生理变化。我将使用一系列技术，包括呼吸测定法，形态计量学和组织学，揭示水生和陆地生命阶段使用的不同策略，以调节其内部氧气和二氧化碳水平及其酸碱平衡。因此，该研究计划解决了我们对昆虫生理学的理解的根本差距，并洞悉了从水到土地过渡的基础呼吸适应的演变。