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Pung-Pung Hwang｜logo Institute of Cellular and Organismic Biology, Academia Sinica

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Professional ExperienceOpenClose
2011-
Jointly-Appointed Professor, Department of Life Science, National Taiwan University
2008-
Distinguished Research Fellow, Institute of Cellular and Organismic Biology, Academia Sinica
1989-2008
Research Fellow, Institute of Zoology/ Cellular and Organismic Biology, Academia Sinica
1989-
Jointly-Appointed Professor, Institute of Fisheries Science, National Taiwan University
1988-1989
Jointly-Appointed Associate Professor, Institute of Fisheries Science, National Taiwan University
1984-1989
Associate Research Fellow, Institute of Zoology, Academia Sinica
1984
Ph.D. in Fisheries Science, University of Tokyo, Japan
1976
B.S. in Zoology, National Taiwan University
Research InterestOpenClose

New models of fish osmoregulation
Osmoregulation is one of the most fundamental aspects of fish physiology. Taking the advantages of molecular manipulation and physiological analysis in zebrafish and medaka, we established new models for fish osmoregulation by identifying different types of gill/skin ionocytes expressing distinct sets of ion transporters for absorption/excretion of various ions, acid-base regulation, and ammonia excretion. These new models are better than traditional species (e.g. salmon and tilapia) for more precisely and comprehensively studying how fish maintain their body fluid ionic and acid-base homeostasis to cope with changing environments. 

Fish physiological mechanisms to cope with changing environment 
Fish have to develop acute responses and long-term acclimation to environmental stresses in order to ensure continued growth/propagation. We adopted the new models to elucidate how fish activate salt or acid secretion (under control of IGF1 and endothelin) within hours and then stimulate proliferation/differentiation of ionocytes and expression of transporters (under control of isotocin and stanniocalcin or others) within several days after exposure to salinity or acid stress. Novel actions of several hormones and their interactions on fish osmoregulation are currently being studied. 

Evolution of internal ionic and acid-base homeostasis 
We compared different groups of vertebrates to propose a possible evolutionary progression of the traits for body fluid ionic and acid-base homeostasis. Lamprey and very few stenohaline freshwater teleosts may have developed H+-ATPase-mediated H+ secretion trait when they initially invaded freshwater habitats. Most of marine and euryhaline species adopted NH4+ excretion as the major way, instead of H+ secretion, for internal acid-base homeostasis; increased NH4+ synthesis and gluconeogenesis may have coevolved, and these traits may have gradually evolved in freshwater fish gills and were also developed in human kidney. These novel findings provide a new foundation for our understanding of ion regulation and environmental adaptation during vertebrate evolution. 

Selected PublicationOpenClose
  1. Shih, S. W., J. J. Yan, Y. H. Wang, Y. L. Tsou, L. Chiu, Y. C. Tseng, M. Y. Chou and P. P. Hwang (2021) Estrogen-related receptor γ2 controls NaCl uptake to maintain ionic homeostasis. J. Endocrinol. 251:149-159. 
  2. Yan, J. J., Y. C. Lee, Y. L. Tsou, Y. C. Tseng and P. P. Hwang (2020) Insulin-like growth factor 1 triggers salt secretion machinery in fish under acute salinity stress. J. Endocrinol. 246:277-288.
  3. Tong, S. K., H. L. Lee, Y. C. Lee, L. C. Wu, Y. L. Tsou, S. W. Lu, S. W. Shih, P. P. Hwang and M. Y. Chou (2020) Arginine vasopressin modulates ion and acid/base balance by regulating cell numbers of sodium chloride cotransporter and H+-ATPase rich ionocytes. Int. J. Mol. Sci. 21:3957.
  4. Tseng, Y. C., J. J. Yan, F. Furukawa and P. P. Hwang (2020) Did acidic stress resistance in vertebrates evolve as Na+/H+ exchanger-mediated ammonia excretion in fish? Bioessays 42: e1900161
  5. Lin, C. H., H. J. Hu and P. P. Hwang (2017) Molecular physiology of the hypocalcemic action of fibroblast growth factor 23 in zebrafish (Danio rerio). Endocrinol. 158: 1-13.
  6. Takei, Y and P. P. Hwang (2016) Homeostatic Responses to Osmotic Stress. In: Schreck C, Tort L (eds.) Fish Physiology-Biology of Stress in Fish. vol 35., pp 208-251. San Diego: Elsevier Academia Press. 
  7. Wang, Y. F., A. G. Lafont, Y. C. Lee and P. P. Hwang (2016) A novel function of calcitonin gene-related peptide in body fluid Cl- homeostasis. Proc. Biol. Sci. 283: 20160684. 
  8. Guh, Y. J., C. Y. Yang, S. T, Liu, C. J. Huang and P. P. Hwang (2016) Oestrogen-related receptor α is required for transepithelial H+ secretion in zebrafish. Proc. Biol. Sci. 283: 20152582.
  9. Hwang P. P., and L. Y. Lin (2013) Gill ion transport, acid-base regulation and nitrogen excretion. In: Evans D, Claiborne JB and Currie S (eds.) The Physiology of Fishes, 4th Edition. pp 205-233. Boca Raton: CRC Press.
  10. Hwang P. P., T. H. Lee and L. Y. Lin (2011) Ion regulation in fish gills: recent progresses in the cellular and molecular mechanisms. Am. J. Physiol. Comparative/Integrative Physiology. 301: R28-R47. (Invited Review)