1
|
Localization of the Neuropeptide Arginine Vasotocin and Its Receptor in the Osmoregulatory Organs of Black Porgy, Acanthopagrus schlegelii: Gills, Kidneys, and Intestines. Int J Mol Sci 2022; 23:ijms232113421. [DOI: 10.3390/ijms232113421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/26/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022] Open
Abstract
The neurohypophysial hormone arginine vasotocin (avt) and its receptor (avtr) regulates ions in the osmoregulatory organs of euryhaline black porgy (Acanthopagrus schlegelii). The localization of avt and avtr transcripts in the osmoregulatory organs has yet to be demonstrated. Thus, in the present study, we performed an in situ hybridization analysis to determine the localization of avt and avtr in the gills, kidneys, and intestines of the black porgy. The avt and avtr transcripts were identified in the filament and lamellae region of the gills in the black porgy. However, the basal membrane of the filament contained more avt and avtr transcripts. Fluorescence double tagging analysis revealed that avt and avtr mRNAs were partially co-localized with α-Nka-ir cells in the gill filament. The proximal tubules, distal tubules, and collecting duct of the kidney all had positive hybridization signals for the avt and avtr transcripts. Unlike the α-Nka immunoreactive cells, the avt and avtr transcripts were found on the basolateral surface of the distal convoluted tubule and in the entire cells of the proximal convoluted tubules of the black porgy kidney. In the intestine, the avt and avtr transcripts were found in the basolateral membrane of the enterocytes. Collectively, this study provides a summary of evidence suggesting that the neuropeptides avt and avtr with α-Nka-ir cells may have functions in the gills, kidneys, and intestines via ionocytes.
Collapse
|
2
|
Vargas-Chacoff L, Martínez D, Oyarzún-Salazar R, Paschke K, Navarro JM. The osmotic response capacity of the Antarctic fish Harpagifer antarcticus is insufficient to cope with projected temperature and salinity under climate change. J Therm Biol 2021; 96:102835. [PMID: 33627273 DOI: 10.1016/j.jtherbio.2021.102835] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 12/04/2020] [Accepted: 01/02/2021] [Indexed: 11/27/2022]
Abstract
Over the last decades, climate change has intensified. Temperatures have increased and seawater has become "fresher" in Antarctica, affecting fish such as Harpagifer antarcticus. Thus, this study aimed to evaluate changes in the osmoregulatory response of the Antarctic notothenioid fish Harpagifer antarcticus and evaluate how it will cope with the future climate change and environmental conditions in the Antarctic, and in the hypothetical case that its geographical distribution will be extended to the Magellanes region. The present study was undertaken to determine the interaction between temperature and salinity tolerance (2 °C and 33 psu as the control group, the experimental groups were 5, 8, and 11 °C and 28 and 23 psu) and their effect on the osmoregulatory status of H. antarcticus. We evaluated changes in gill-kidney-intestine NKA activity, gene expression of NKAα, NKCC, CFTR, Aquaporins 1 and 8 in the same tissues, muscle water percentage, and plasma osmolality to evaluate osmoregulatory responses. Plasma osmolality decreased with high temperature, also the gill-kidney-intestine NKA activity, gene expression of NKA α, NKCC, CFTR, Aquaporins 1, and 8 were modified by temperature and salinity. We demonstrated that H. antarcticus can not live in the Magallanes region, due to its incapacity to put up with temperatures over 5 °C and with over 8 °C being catastrophic.
Collapse
Affiliation(s)
- L Vargas-Chacoff
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile; Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile.
| | - D Martínez
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile; Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile
| | - R Oyarzún-Salazar
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile; Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile; Escuela de Graduados Programa de Doctorado en Ciencias de la Acuicultura, Universidad Austral de Chile, Puerto Montt, Chile
| | - K Paschke
- Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile; Instituto de Acuicultura, Universidad Austral de Chile, Puerto Montt, Chile
| | - J M Navarro
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile; Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile
| |
Collapse
|
3
|
An osmolality/salinity-responsive enhancer 1 (OSRE1) in intron 1 promotes salinity induction of tilapia glutamine synthetase. Sci Rep 2020; 10:12103. [PMID: 32694739 PMCID: PMC7374092 DOI: 10.1038/s41598-020-69090-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 06/11/2020] [Indexed: 01/02/2023] Open
Abstract
Euryhaline tilapia (Oreochromis mossambicus) are fish that tolerate a wide salinity range from fresh water to > 3× seawater. Even though the physiological effector mechanisms of osmoregulation that maintain plasma homeostasis in fresh water and seawater fish are well known, the corresponding molecular mechanisms that control switching between hyper- (fresh water) and hypo-osmoregulation (seawater) remain mostly elusive. In this study we show that hyperosmotic induction of glutamine synthetase represents a prominent part of this switch. Proteomics analysis of the O. mossambicus OmB cell line revealed that glutamine synthetase is transcriptionally regulated by hyperosmolality. Therefore, the 5' regulatory sequence of O. mossambicus glutamine synthetase was investigated. Using an enhancer trapping assay, we discovered a novel osmosensitive mechanism by which intron 1 positively mediates glutamine synthetase transcription. Intron 1 includes a single, functional copy of an osmoresponsive element, osmolality/salinity-responsive enhancer 1 (OSRE1). Unlike for conventional enhancers, the hyperosmotic induction of glutamine synthetase by intron 1 is position dependent. But irrespective of intron 1 position, OSRE1 deletion from intron 1 abolishes hyperosmotic enhancer activity. These findings indicate that proper intron 1 positioning and the presence of an OSRE1 in intron 1 are required for precise enhancement of hyperosmotic glutamine synthetase expression.
Collapse
|
4
|
Huang PC, Liu TY, Hu MY, Casties I, Tseng YC. Energy and nitrogenous waste from glutamate/glutamine catabolism facilitates acute osmotic adjustment in non-neuroectodermal branchial cells. Sci Rep 2020; 10:9460. [PMID: 32528019 PMCID: PMC7289822 DOI: 10.1038/s41598-020-65913-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 05/12/2020] [Indexed: 11/30/2022] Open
Abstract
Maintenance of homeostasis is one of the most important physiological responses for animals upon osmotic perturbations. Ionocytes of branchial epithelia are the major cell types responsible for active ion transport, which is mediated by energy-consuming ion pumps (e.g., Na+-K+-ATPase, NKA) and secondary active transporters. Consequently, in addition to osmolyte adjustments, sufficient and immediate energy replenishment is essenttableial for acclimation to osmotic changes. In this study, we propose that glutamate/glutamine catabolism and trans-epithelial transport of nitrogenous waste may aid euryhaline teleosts Japanese medaka (Oryzias latipes) during acclimation to osmotic changes. Glutamate family amino acid contents in gills were increased by hyperosmotic challenge along an acclimation period of 72 hours. This change in amino acids was accompanied by a stimulation of putative glutamate/glutamine transporters (Eaats, Sat) and synthesis enzymes (Gls, Glul) that participate in regulating glutamate/glutamine cycling in branchial epithelia during acclimation to hyperosmotic conditions. In situ hybridization of glutaminase and glutamine synthetase in combination with immunocytochemistry demonstrate a partial colocalization of olgls1a and olgls2 but not olglul with Na+/K+-ATPase-rich ionocytes. Also for the glutamate and glutamine transporters colocalization with ionocytes was found for oleaat1, oleaat3, and olslc38a4, but not oleaat2. Morpholino knock-down of Sat decreased Na+ flux from the larval epithelium, demonstrating the importance of glutamate/glutamine transport in osmotic regulation. In addition to its role as an energy substrate, glutamate deamination produces NH4+, which may contribute to osmolyte production; genes encoding components of the urea production cycle, including carbamoyl phosphate synthetase (CPS) and ornithine transcarbamylase (OTC), were upregulated under hyperosmotic challenges. Based on these findings the present work demonstrates that the glutamate/glutamine cycle and subsequent transepithelial transport of nitrogenous waste in branchial epithelia represents an essential component for the maintenance of ionic homeostasis under a hyperosmotic challenge.
Collapse
Affiliation(s)
- Pei-Chen Huang
- Marine Research Station, Institute of Cellular and organismic Biology, Academia Sinica, I-Lan County, Taiwan (ROC)
| | - Tzu-Yen Liu
- Marine Research Station, Institute of Cellular and organismic Biology, Academia Sinica, I-Lan County, Taiwan (ROC)
| | - Marian Y Hu
- Institute of Physiology, Christian-Albrechts University Kiel, Kiel, Germany
| | - Isabel Casties
- Helmholtz Centre for Ocean Research Kiel (GEOMAR), Kiel, Germany
| | - Yung-Che Tseng
- Marine Research Station, Institute of Cellular and organismic Biology, Academia Sinica, I-Lan County, Taiwan (ROC).
| |
Collapse
|
5
|
Williams M, Barranca D, Bucking C. Zonation of Ca 2+ transport and enzyme activity in the caeca of rainbow trout - a simple structure with complex functions. ACTA ACUST UNITED AC 2019; 222:jeb.187484. [PMID: 30765468 DOI: 10.1242/jeb.187484] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Accepted: 02/07/2019] [Indexed: 11/20/2022]
Abstract
Trout caeca are vermiform structures projecting from the anterior intestine of the gastrointestinal tract. Despite their simple gross morphology, these appendages are physically distinct along the anterior-posterior axis, and ultrastructural evidence suggests zonation of function within the structures. Individual caeca from three sections (anterior, middle and posterior) were removed from the intestine of freshwater rainbow trout and investigated for ion transport and enzyme activity. Ca2+ absorption appeared as a combination of active and passive movement, with Michaelis-Menten kinetics observable under symmetrical conditions, and was inhibited by several pharmacological agents (ouabain, La3+ and a calmodulin antagonist). There was a decrease in ion transport function from adjacent to the intestine (proximal) to the distal tip of each caecum, along with decreasing transport from anterior to posterior for the proximal portion alone. Feeding increased the J Max and K M for Ca2+ absorption within all sections, whereas ion-poor water (IPW) exposure further increased the J Max and K M for Ca2+ transport in the anterior and middle sections. Increased Na+/K+-ATPase (NKA) and citrate synthase (CS) activity rates paralleled trends seen in Ca2+ transport. Feeding in freshwater and IPW exposure increased the glycolytic capacity of the caeca via increased pyruvate kinase (PK) and decreased lactate dehydrogenase (LDH) activity, while amino acid metabolism increased with IPW exposure through increased glutamate dehydrogenase (GDH) activity. Overall, feeding and IPW exposure each altered ionoregulation within the caeca of freshwater rainbow trout in a zone-specific pattern, with the anterior and proximal portions of the caeca being most affected. Increased carbohydrate and protein metabolism fueled the increased ATP demand of NKA through CS.
Collapse
Affiliation(s)
- Melanie Williams
- Department of Biology, York University, Toronto, Ontario, Canada, M3J 1P3
| | - Domenico Barranca
- Department of Biology, York University, Toronto, Ontario, Canada, M3J 1P3
| | - Carol Bucking
- Department of Biology, York University, Toronto, Ontario, Canada, M3J 1P3
| |
Collapse
|
6
|
Yang WK, Hsu AD, Kang CK, Lai IP, Liao PS, Lee TH. Intestinal FXYD12 and sodium-potassium ATPase: A comparative study on two euryhaline medakas in response to salinity changes. PLoS One 2018; 13:e0201252. [PMID: 30052675 PMCID: PMC6063443 DOI: 10.1371/journal.pone.0201252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 07/11/2018] [Indexed: 11/18/2022] Open
Abstract
FXYD proteins are the regulators of sodium-potassium ATPase (Na+/K+-ATPase, NKA). In teleosts, NKA is a primary driving force for the operation of many ion transport systems in the osmoregulatory organs (e.g. intestines). Hence, the purpose of this study was to determine the expression of FXYD proteins and NKA α-subunit in the intestines of two closely related medakas (Oryzias dancena and O. latipes), which came from different salinity habitats and have diverse osmoregulatory capabilities, to illustrate the association between NKA and FXYD proteins of two medaka species in response to salinity changes. The results showed that the fxyd12 mRNA was the most predominant in the intestines of both medakas. The association of FXYD12 and NKA in the intestines of the two medaka species was demonstrated via double immunofluorescent staining and co-immunoprecipitation. Upon salinity challenge, the localization of FXYD12 and NKA was similar in the intestines of the two medaka species. However, the expression profiles of intestinal FXYD12 and NKA (mRNA and protein levels), as well as NKA activity differed between the medakas. These results showed that FXYD12 may play a role in modulating NKA activity in the intestines of the two medakas following salinity changes in the maintenance of internal homeostasis. These findings contributed to knowledge of the expression and potential role of vertebrate FXYD12, the regulators of NKA, upon salinity challenge.
Collapse
Affiliation(s)
- Wen-Kai Yang
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan
- The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
- Bachelor Degree Program in Animal Healthcare, Hungkuang University, Taichung, Taiwan
| | - An-Di Hsu
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan
| | - Chao-Kai Kang
- Tainan Hydraulics Laboratory, National Cheng Kung University, Tainan, Taiwan
| | - Ivan Pochou Lai
- National Taichung First Senior High School, Taichung, Taiwan
| | - Pei-Shao Liao
- National Taichung First Senior High School, Taichung, Taiwan
| | - Tsung-Han Lee
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan
- The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
- * E-mail:
| |
Collapse
|
7
|
Sundh H, Nilsen TO, Lindström J, Hasselberg-Frank L, Stefansson SO, McCormick SD, Sundell K. Development of intestinal ion-transporting mechanisms during smoltification and seawater acclimation in Atlantic salmon Salmo salar. JOURNAL OF FISH BIOLOGY 2014; 85:1227-52. [PMID: 25263190 DOI: 10.1111/jfb.12531] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 08/11/2014] [Indexed: 05/13/2023]
Abstract
This study investigated the expression of ion transporters involved in intestinal fluid absorption and presents evidence for developmental changes in abundance and tissue distribution of these transporters during smoltification and seawater (SW) acclimation of Atlantic salmon Salmo salar. Emphasis was placed on Na(+) , K(+) -ATPase (NKA) and Na(+) , K(+) , Cl(-) co-transporter (NKCC) isoforms, at both transcriptional and protein levels, together with transcription of chloride channel genes. The nka α1c was the dominant isoform at the transcript level in both proximal and distal intestines; also, it was the most abundant isoform expressed in the basolateral membrane of enterocytes in the proximal intestine. This isoform was also abundantly expressed in the distal intestine in the lower part of the mucosal folds. The protein expression of intestinal Nkaα1c increased during smoltification. Immunostaining was localized to the basal membrane of the enterocytes in freshwater (FW) fish, and re-distributed to a lateral position after SW entry. Two other Nka isoforms, α1a and α1b, were expressed in the intestine but were not regulated to the same extent during smoltification and subsequent SW transfer. Their localization in the intestinal wall indicates a house-keeping function in excitatory tissues. The absorptive form of the NKCC-like isoform (sub-apically located NKCC2 and/or Na(+) , Cl(-) co-transporter) increased during smoltification and further after SW transfer. The cellular distribution changed from a diffuse expression in the sub-apical regions during smoltification to clustering of the transporters closer to the apical membrane after entry to SW. Furthermore, transcript abundance indicates that the mechanisms necessary for exit of chloride ions across the basolateral membrane and into the lateral intercellular space are present in the form of one or more of three different chloride channels: cystic fibrosis transmembrane conductance regulator I and II and chloride channel 3.
Collapse
Affiliation(s)
- H Sundh
- Fish Endocrinology Laboratory, Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, 40530 Gothenburg, Sweden
| | | | | | | | | | | | | |
Collapse
|
8
|
Environmental salinity-modified osmoregulatory response in the sub-Antarctic notothenioid fish Eleginops maclovinus. Polar Biol 2014. [DOI: 10.1007/s00300-014-1515-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
9
|
Brain Na+/K+-ATPase α-subunit isoforms and aestivation in the African lungfish, Protopterus annectens. J Comp Physiol B 2014; 184:571-87. [PMID: 24696295 DOI: 10.1007/s00360-014-0809-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 01/16/2014] [Accepted: 01/24/2014] [Indexed: 10/25/2022]
Abstract
This study aimed to clone and sequence Na (+) / K (+)-ATPase (nka) α-subunit isoforms from, and to determine their mRNA expression levels and protein abundance in the brain of the African lungfish, Protopterus annectens during the induction, maintenance and arousal phases of aestivation in air. We obtained the full cDNA sequences of nkaα1, nkaα2 and nkaα3 from the brain of P. annectens. Phylogenetic analysis of their deduced amino acid sequences revealed that they are closer to the corresponding NKA α-subunits of tetrapods than to those of fishes. The mRNA expression of these three nkaα isoforms showed differential changes in the brain of P. annectens during the three phases of aestivation. After 12 days of aestivation, there was a significant increase in the protein abundance of Nkaα1 in the brain of P. annectens. This could be an important response to maintain cellular Na(+) and K(+) concentrations and regulate cell volume during the early maintenance phase of aestivation. On the other hand, the mRNA expression of nkaα2 decreased significantly in the brain of P. annectens after 6 months of aestivation, which could be a result of a suppression of transcriptional activities to reduce energy expenditure. The down-regulation of mRNA expression of nkaα1, nkaα2 and nkaα3 and the overall protein abundance of Nka α-subunit isoforms in the brain of P. annectens after 1 day of arousal from 6 months of aestivation were novel observations, and it could be an adaptive response to restore blood pressure and/or to prevent brain oedema.
Collapse
|
10
|
Tok CY, Chew SF, Ip YK. Gene Cloning and mRNA Expression of Glutamate Dehydrogenase in the Liver, Brain, and Intestine of the Swamp Eel, Monopterus albus (Zuiew), Exposed to Freshwater, Terrestrial Conditions, Environmental Ammonia, or Salinity Stress. Front Physiol 2011; 2:100. [PMID: 22319499 PMCID: PMC3267175 DOI: 10.3389/fphys.2011.00100] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 11/24/2011] [Indexed: 01/07/2023] Open
Abstract
The swamp eel, Monopterus albus, is an obligatory air-breathing teleost which can undergo long period of emersion, has high environmental and tissue ammonia tolerance, and can survive in brackish water. We obtained a cDNA sequence of glutamate dehydrogenase (gdh), which consisted of a 133-bp 5′ UTR, a complete coding sequence region spanning 1629 bp and a 3′ UTR of approximately 717 bp, from the liver, intestine, and brain of M. albus. The translated Gdh amino acid sequence had 542 residues, and it formed a monophyletic clade with Bostrychus sinensis Gdh1a, Tetraodon nigroviridis Gdh1a, Chaenocephalus aceratus Gdh1a, Salmo salar Gdh1a1 and Gdh1a2, and O. mykiss Gdh1a. One day of exposure to terrestrial conditions or 75 mmol l−1 NH4Cl, but not to water at salinity 20, resulted in a significant increase in mRNA expression of gdh1a and Gdh amination activity in the liver of M. albus. However, exposure to brackish water, but not to terrestrial conditions or 75 mmol l−1 NH4Cl, led to a significant increase in the mRNA expression of gdh1a and Gdh amination activity in the intestine. By contrast, all the three experimental conditions had no significant effects on the mRNA expression of gdh1a in the brain of M. albus, despite a significant decrease in the Gdh amination activity in the brain of fish exposed to 75 mmol l−1 NH4Cl for 6 days. Our results indicate for the first time that the mRNA expression of gdh1a was differentially up-regulated in the liver and intestine of M. albus in response to ammonia toxicity and salinity stress, respectively. The increases in mRNA expression of gdh1a and Gdh amination activity would probably lead to an increase in glutamate production in support of increased glutamine synthesis for the purpose of ammonia detoxification or cell volume regulation under these two different environmental conditions.
Collapse
Affiliation(s)
- Chia Y Tok
- Department of Biological Science, National University of Singapore Singapore
| | | | | |
Collapse
|
11
|
Einarsdóttir IE, Power DM, Jönsson E, Björnsson BT. Occurrence of ghrelin-producing cells, the ghrelin receptor and Na+,K+-ATPase in tissues of Atlantic halibut (Hippoglossus hippoglossus) during early development. Cell Tissue Res 2011; 344:481-98. [DOI: 10.1007/s00441-011-1158-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 02/24/2011] [Indexed: 10/18/2022]
|
12
|
Ip YK, Chew SF. Ammonia production, excretion, toxicity, and defense in fish: a review. Front Physiol 2010; 1:134. [PMID: 21423375 PMCID: PMC3059970 DOI: 10.3389/fphys.2010.00134] [Citation(s) in RCA: 164] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2010] [Accepted: 09/06/2010] [Indexed: 12/20/2022] Open
Abstract
Many fishes are ammonotelic but some species can detoxify ammonia to glutamine or urea. Certain fish species can accumulate high levels of ammonia in the brain or defense against ammonia toxicity by enhancing the effectiveness of ammonia excretion through active NH4+transport, manipulation of ambient pH, or reduction in ammonia permeability through the branchial and cutaneous epithelia. Recent reports on ammonia toxicity in mammalian brain reveal the importance of permeation of ammonia through the blood-brain barrier and passages of ammonia and water through transporters in the plasmalemma of brain cells. Additionally, brain ammonia toxicity could be related to the passage of glutamine through the mitochondrial membranes into the mitochondrial matrix. On the other hand, recent reports on ammonia excretion in fish confirm the involvement of Rhesus glycoproteins in the branchial and cutaneous epithelia. Therefore, this review focuses on both the earlier literature and the up-to-date information on the problems and mechanisms concerning the permeation of ammonia, as NH(3), NH4+ or proton-neutral nitrogenous compounds, across mitochondrial membranes, the blood-brain barrier, the plasmalemma of neurons, and the branchial and cutaneous epithelia of fish. It also addresses how certain fishes with high ammonia tolerance defend against ammonia toxicity through the regulation of the permeation of ammonia and related nitrogenous compounds through various types of membranes. It is hoped that this review would revive the interests in investigations on the passage of ammonia through the mitochondrial membranes and the blood-brain barrier of ammonotelic fishes and fishes with high brain ammonia tolerance, respectively.
Collapse
Affiliation(s)
- Yuen K Ip
- Department of Biological Sciences, National University of Singapore Singapore, Republic of Singapore.
| | | |
Collapse
|
13
|
|
14
|
Taylor J, Cooper C, Mommsen T. Implications of GI function for gas exchange, acid–base balance and nitrogen metabolism. FISH PHYSIOLOGY 2010. [DOI: 10.1016/s1546-5098(10)03006-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|