Please use this identifier to cite or link to this item:
Ip, Y. K., & Chew, S. F. (2018). Air-breathing and excretory nitrogen metabolism in fishes. Acta Histochemica,120(7), 680-690. https://doi.org/10.1016/j.acthis.2018.08.013
During water-land transition, ancient fishes acquired the ability to breathe air, but air-breathing engendered problems in nitrogenous waste excretion. Nitrogen is a fundamental component of amino acids, proteins, and nucleic acids, and the degradation of these nitrogen-containing compounds releases ammonia. Ammonia is toxic and must be removed. Fishes in water excrete ammonia as the major nitrogenous waste through gills, but gills of air-breathing fishes are modified for air-breathing or largely replaced by air-breathing organs. Notably, fishes emerged from water can no longer excrete ammonia effectively because of a lack of water to flush the gills. Hence, ancient fishes that participated in water-land transition must have developed means to deal with ammonia toxicity. Extant air-breathing fishes, particularly amphibious ones, can serve as models to examine adaptations which might have facilitated the emergence of ancient fishes from water. Some of these fishes can actively emerge from water and display complex behaviors on land, while a few can burrow into mud and survive for years during drought. Many of them are equipped with mechanisms to ameliorate ammonia toxicity during emersion. In this review, the mechanisms adopted by air-breathing fishes to deal with ammonia toxicity during emersion were organized into seven disparate strategies. In addition, eight extant air-breathing fishes with distinctive terrestrial behaviors and peculiar natural habitats were selected to describe in detail how these seven strategies could be adopted in disparate combinations to ameliorate ammonia toxicity during emersion.
This is the final draft, after peer-review, of a manuscript published in Acta Histochemica. The published version is available online at https://doi.org/10.1016/j.acthis.2018.08.013
|Appears in Collections:||Journal Articles|
Show full item record
Files in This Item:
|AH-120-7-680.pdf||771.16 kB||Adobe PDF|
checked on Mar 25, 2023
WEB OF SCIENCETM
checked on Mar 23, 2023
Page view(s) 50136
checked on Mar 30, 2023
checked on Mar 30, 2023
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.