From Water to Land: The Structural Construction and Molecular Switches in Lungs during Metamorphosis of Microhyla fissipes
1
CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, University of Chinese Academy of Sciences, Chengdu 610041, China
2
University of Chinese Academy of Sciences, Beijing 100049, China
*
Authors to whom correspondence should be addressed.
Academic Editor: Daniel G. Peterson
Biology 2022, 11(4), 528; https://doi.org/10.3390/biology11040528
Received: 19 January 2022
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Revised: 16 March 2022
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Accepted: 24 March 2022
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Published: 30 March 2022
(This article belongs to the Section Zoology)
Simple Summary
The functionalization of lungs is a necessity for most anurans to breathe on land. Previous studies have focused on the morphological and physiological functions of amphibian lungs, while the microstructural changes and molecular mechanisms that underpin the functional maturation of lungs remain under-researched. We used integrated histology and transcriptomics to study the critical cytological and molecular events associated with lung maturation in Microhyla fissipes. The results illuminated the molecular processes and their coordination in lung development, providing an insight into the transition of amphibians from aquatic to terrestrial life stages.
Most anurans must undergo metamorphosis to adapt to terrestrial life. This process enhances the air-breathing ability of the lungs to cope with the change in oxygen medium from water to air. Revealing the structural construction and molecular switches of lung organogenesis is essential to understanding the realization of the air-breathing function. In this study, histology and transcriptomics were conducted in combination to explore these issues in Microhyla fissipes’ lungs during metamorphosis. During the pro-metamorphic phase, histological structural improvement of the alveolar wall is accompanied by robust substrate metabolism and protein turnover. The lungs, at the metamorphic climax phase, are characterized by an increased number of cilia in the alveolar epithelial cells and collagenous fibers in the connective tissues, corresponding to the transcriptional upregulation of cilia and extracellular matrix-related genes. Post-metamorphic lungs strengthen their contracting function, as suggested by the thickened muscle layer and the upregulated expression of genes involved in muscle contraction. The blood–gas barrier is fully developed in adult lungs, the transcriptional features of which are tissue growth and regulation of differentiation and immunity. Importantly, significant transcriptional switches of pulmonary surfactant protein and hemoglobin facilitate air breathing. Our results illuminated four key steps of lung development for amphibians to transition from water to land.
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Keywords:
WGCNA; lung development; histological structure; molecular changes; amphibian
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MDPI and ACS Style
Chang, L.; Zhang, M.; Chen, Q.; Liu, J.; Zhu, W.; Jiang, J. From Water to Land: The Structural Construction and Molecular Switches in Lungs during Metamorphosis of Microhyla fissipes. Biology 2022, 11, 528. https://doi.org/10.3390/biology11040528
AMA Style
Chang L, Zhang M, Chen Q, Liu J, Zhu W, Jiang J. From Water to Land: The Structural Construction and Molecular Switches in Lungs during Metamorphosis of Microhyla fissipes. Biology. 2022; 11(4):528. https://doi.org/10.3390/biology11040528
Chicago/Turabian StyleChang, Liming, Meihua Zhang, Qiheng Chen, Jiongyu Liu, Wei Zhu, and Jianping Jiang. 2022. "From Water to Land: The Structural Construction and Molecular Switches in Lungs during Metamorphosis of Microhyla fissipes" Biology 11, no. 4: 528. https://doi.org/10.3390/biology11040528
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