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The Non-ureogenic Stinging Catfish, Heteropneustes fossilis, Actively Excretes Ammonia With the Help of Na(+)/K(+)-ATPase When Exposed to Environmental Ammonia
The stinging catfish, Heteropneustes fossilis, can tolerate high concentrations of environmental ammonia. Previously, it was regarded as ureogenic, having a functional ornithine-urea cycle (OUC) that could be up-regulated during ammonia-loading. However, contradictory results indicated that increase...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Frontiers Media S.A.
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6987325/ https://www.ncbi.nlm.nih.gov/pubmed/32038295 http://dx.doi.org/10.3389/fphys.2019.01615 |
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author | Chew, Shit F. Tan, Stephanie Z. L. Ip, Sabrina C. Y. Pang, Caryn Z. Hiong, Kum C. Ip, Yuen K. |
author_facet | Chew, Shit F. Tan, Stephanie Z. L. Ip, Sabrina C. Y. Pang, Caryn Z. Hiong, Kum C. Ip, Yuen K. |
author_sort | Chew, Shit F. |
collection | PubMed |
description | The stinging catfish, Heteropneustes fossilis, can tolerate high concentrations of environmental ammonia. Previously, it was regarded as ureogenic, having a functional ornithine-urea cycle (OUC) that could be up-regulated during ammonia-loading. However, contradictory results indicated that increased urea synthesis and switching to ureotelism could not explain its high ammonia tolerance. Hence, we re-examined the effects of exposure to 30 mmol l(–1) NH(4)Cl on its ammonia and urea excretion rates, and its tissue ammonia and urea concentrations. Our results confirmed that H. fossilis did not increase urea excretion or accumulation during 6 days of ammonia exposure, and lacked detectable carbamoyl phosphate synthetase I or III activity in its liver. However, we discovered that it could actively excrete ammonia during exposure to 8 mmol l(–1) NH(4)Cl. As active ammonia excretion is known to involve Na(+)/K(+)-ATPase (Nka) indirectly in several ammonia-tolerant fishes, we also cloned various nkaα-subunit isoforms from the gills of H. fossilis, and determined the effects of ammonia exposure on their branchial transcripts levels and protein abundances. Results obtained revealed the presence of five nkaα-subunit isoforms, with nkaα1b having the highest transcript level. Exposure to 30 mmol l(–1) NH(4)Cl led to significant increases in the transcript levels of nkaα1b (on day 6) and nkaα1c1 (on day 1 and 3) as compared with the control. In addition, the protein abundances of Nkaα1c1, Nkaα1c2, and total NKAα increased significantly on day 6. Therefore, the high environmental ammonia tolerance of H. fossilis is attributable partly to its ability to actively excrete ammonia with the aid of Nka. |
format | Online Article Text |
id | pubmed-6987325 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-69873252020-02-07 The Non-ureogenic Stinging Catfish, Heteropneustes fossilis, Actively Excretes Ammonia With the Help of Na(+)/K(+)-ATPase When Exposed to Environmental Ammonia Chew, Shit F. Tan, Stephanie Z. L. Ip, Sabrina C. Y. Pang, Caryn Z. Hiong, Kum C. Ip, Yuen K. Front Physiol Physiology The stinging catfish, Heteropneustes fossilis, can tolerate high concentrations of environmental ammonia. Previously, it was regarded as ureogenic, having a functional ornithine-urea cycle (OUC) that could be up-regulated during ammonia-loading. However, contradictory results indicated that increased urea synthesis and switching to ureotelism could not explain its high ammonia tolerance. Hence, we re-examined the effects of exposure to 30 mmol l(–1) NH(4)Cl on its ammonia and urea excretion rates, and its tissue ammonia and urea concentrations. Our results confirmed that H. fossilis did not increase urea excretion or accumulation during 6 days of ammonia exposure, and lacked detectable carbamoyl phosphate synthetase I or III activity in its liver. However, we discovered that it could actively excrete ammonia during exposure to 8 mmol l(–1) NH(4)Cl. As active ammonia excretion is known to involve Na(+)/K(+)-ATPase (Nka) indirectly in several ammonia-tolerant fishes, we also cloned various nkaα-subunit isoforms from the gills of H. fossilis, and determined the effects of ammonia exposure on their branchial transcripts levels and protein abundances. Results obtained revealed the presence of five nkaα-subunit isoforms, with nkaα1b having the highest transcript level. Exposure to 30 mmol l(–1) NH(4)Cl led to significant increases in the transcript levels of nkaα1b (on day 6) and nkaα1c1 (on day 1 and 3) as compared with the control. In addition, the protein abundances of Nkaα1c1, Nkaα1c2, and total NKAα increased significantly on day 6. Therefore, the high environmental ammonia tolerance of H. fossilis is attributable partly to its ability to actively excrete ammonia with the aid of Nka. Frontiers Media S.A. 2020-01-22 /pmc/articles/PMC6987325/ /pubmed/32038295 http://dx.doi.org/10.3389/fphys.2019.01615 Text en Copyright © 2020 Chew, Tan, Ip, Pang, Hiong and Ip. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
spellingShingle | Physiology Chew, Shit F. Tan, Stephanie Z. L. Ip, Sabrina C. Y. Pang, Caryn Z. Hiong, Kum C. Ip, Yuen K. The Non-ureogenic Stinging Catfish, Heteropneustes fossilis, Actively Excretes Ammonia With the Help of Na(+)/K(+)-ATPase When Exposed to Environmental Ammonia |
title | The Non-ureogenic Stinging Catfish, Heteropneustes fossilis, Actively Excretes Ammonia With the Help of Na(+)/K(+)-ATPase When Exposed to Environmental Ammonia |
title_full | The Non-ureogenic Stinging Catfish, Heteropneustes fossilis, Actively Excretes Ammonia With the Help of Na(+)/K(+)-ATPase When Exposed to Environmental Ammonia |
title_fullStr | The Non-ureogenic Stinging Catfish, Heteropneustes fossilis, Actively Excretes Ammonia With the Help of Na(+)/K(+)-ATPase When Exposed to Environmental Ammonia |
title_full_unstemmed | The Non-ureogenic Stinging Catfish, Heteropneustes fossilis, Actively Excretes Ammonia With the Help of Na(+)/K(+)-ATPase When Exposed to Environmental Ammonia |
title_short | The Non-ureogenic Stinging Catfish, Heteropneustes fossilis, Actively Excretes Ammonia With the Help of Na(+)/K(+)-ATPase When Exposed to Environmental Ammonia |
title_sort | non-ureogenic stinging catfish, heteropneustes fossilis, actively excretes ammonia with the help of na(+)/k(+)-atpase when exposed to environmental ammonia |
topic | Physiology |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6987325/ https://www.ncbi.nlm.nih.gov/pubmed/32038295 http://dx.doi.org/10.3389/fphys.2019.01615 |
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