Emergence of air breathing in vertebrates

脊椎动物呼吸空气的出现

• 批准号: RGPIN-2016-05848
• 负责人: Kinkead, Richard
• 金额: $ 2.99万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=615941
• 关键词: Emergence; air; breathing; vertebrates

The transition from water to air breathing is arguably the most spectacular change in animal physiology. Given the substantial differences in physico-chemical properties between water and air, a successful transition in respiratory medium requires significant transformations in the neural circuits that generate and regulate breathing. Using the American bullfrog (Lithobates catesbeianus) as our main model system, the long term objective of my research program is to understand the neurophysiological changes within the respiratory control system associated with the emergence of air breathing in vertebrates. During early life, tadpoles ventilate their gills by producing a continuous, high frequency, low amplitude activation of the buccal pump. As the lungs develop, a more forceful but less frequent activation of the buccal pump emerges progressively to push air into the lungs. Experiments performed on isolated brainstems (in vitro) from pre-metamorphic tadpoles show that the circuits driving lung ventilation are present well before air breathing contributes to gas exchange but is inhibited. In light of the evidence indicating that expression of the motor command producing lung ventilation is highly plastic, we propose to combine electrophysiological studies (isolated brainstem preparation, whole cell recording with patch clamp) with whole animal measurements of respiratory activity (in vivo) to address the following specific aims: 1) The electrical properties and morphology of trigeminal motoneurons undergo significant changes during development. 2) Developmental changes in acid-base status contribute to the emergence of air breathing. 3) Thyroid hormone (TH) facilitates the expression of air breathing in pre-metamorphic tadpoles. 4) Brainstem hypoxia is sufficient to facilitate expression of air breathing in pre-metamorphic tadpoles. The research proposed for the next grant cycle is an important milestone in my research program and the outcome will advance basic knowledge in respiratory neurobiology. By combining simple experiments with “state of the art” electrophysiological approaches, this program will help trainees acquire basic expertise in research as well as highly desirable skills regardless of the stage of their academic training.

从水呼吸到空气呼吸的转变可以说是动物生理上最壮观的变化。鉴于水和空气在物理化学性质上的巨大差异，在呼吸介质中成功转换需要产生和调节呼吸的神经回路发生重大转变。以美洲牛蛙（Lithobates catesbeianus）作为我们的主要模型系统，我的研究计划的长期目标是了解与脊椎动物空气呼吸出现相关的呼吸控制系统内的神经生理变化。