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Talwar C, Nagar S, Negi RK. Comparative analyses of gut microbiota reveal ammonia detoxification and nitrogen assimilation in Cyprinus carpio var. specularis. Folia Microbiol (Praha) 2024; 69:1029-1041. [PMID: 38367166 DOI: 10.1007/s12223-024-01151-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 02/08/2024] [Indexed: 02/19/2024]
Abstract
The complex niche of fish gut is often characterized by the associated microorganisms that have implications in fish gut-health nexus. Although efforts to distinguish the microbial communities have highlighted their disparate structure along the gut length, remarkably little information is available about their distinct structural and functional profiles in different gut compartments in different fish species. Here, we performed comparative taxonomic and predictive functional analyses of the foregut and hindgut microbiota in an omnivorous freshwater fish species, Cyprinus carpio var. specularis, commonly known as mirror carp. Our analyses showed that the hindgut microbiota could be distinguished from foregut based on the abundance of ammonia-oxidizing, denitrifying, and nitrogen-fixing commensals of families such as Rhodospirillaceae, Oxalobacteraceae, Nitrosomonadaceae, and Nitrospiraceae. Functionally, unique metabolic pathways such as degradation of lignin, 2-nitrobenzoate, vanillin, vanillate, and toluene predicted within hindgut also hinted at the ability of hindgut microbiota for assimilation of nitrogen and detoxification of ammonia. The study highlights a major role of hindgut microbiota in assimilating nitrogen, which remains to be one of the limiting nutrients within the gut of mirror carp.
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Affiliation(s)
- Chandni Talwar
- Fish Molecular Biology Laboratory, Department of Zoology, University of Delhi, Delhi, 110007, India
- Department of Pathology & Immunology, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, 770030, USA
| | - Shekhar Nagar
- Fish Molecular Biology Laboratory, Department of Zoology, University of Delhi, Delhi, 110007, India
- Department of Zoology, Deshbandhu College, Kalkaji, New Delhi, 110019, India
| | - Ram Krishan Negi
- Fish Molecular Biology Laboratory, Department of Zoology, University of Delhi, Delhi, 110007, India.
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Wood CM, Wang J, Jung EH, Pelster B. The physiological consequences of a very large natural meal in a voracious marine fish, the staghorn sculpin (Leptocottus armatus). J Exp Biol 2023; 226:jeb246034. [PMID: 37675481 DOI: 10.1242/jeb.246034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 08/26/2023] [Indexed: 09/08/2023]
Abstract
Little information exists on physiological consequences when wild fish eat natural food. Staghorn sculpins at 10-13°C voluntarily consumed 15.8% of their body mass in anchovies. Gastric clearance was slow with >60% of the meal retained in the stomach at 48 h, and was not complete until 84 h. At 14-24 h post-feeding, pH was depressed by 3 units and Cl- concentration was elevated 2-fold in gastric chyme, reflecting HCl secretion, while in all sections of the intestine, pH declined by 1 pH unit but Cl- concentration remained unchanged. PCO2 and total ammonia concentration were greatly elevated throughout the tract, whereas PNH3 and HCO3- concentration were depressed. Intestinal HCO3- secretion rates, measured in gut sacs in vitro, were also lower in fed fish. Whole-animal O2 consumption rate was elevated approximately 2-fold for 72 h post-feeding, reflecting 'specific dynamic action', whereas ammonia and urea-N excretion rates were elevated about 5-fold. Arterial blood exhibited a modest 'alkaline tide' for about 48 h, but there was negligible excretion of metabolic base to the external seawater. PaCO2 and PaO2 remained unchanged. Plasma total amino acid concentration and total lipid concentration were elevated about 1.5-fold for at least 48 h, whereas small increases in plasma total ammonia concentration, PNH3 and urea-N concentration were quickly attenuated. Plasma glucose concentration remained unchanged. We conclude that despite the very large meal, slow processing with high efficiency minimizes internal physiological disturbances. This differs greatly from the picture provided by previous studies on aquacultured species using synthetic diets and/or force-feeding. Questions remain about the role of the gastro-intestinal microbiome in nitrogen and acid-base metabolism.
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Affiliation(s)
- Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
- Bamfield Marine Sciences Centre, Bamfield, BC, Canada, V0R 1B0
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
| | - Jun Wang
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
- Bamfield Marine Sciences Centre, Bamfield, BC, Canada, V0R 1B0
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Ellen H Jung
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
- Bamfield Marine Sciences Centre, Bamfield, BC, Canada, V0R 1B0
| | - Bernd Pelster
- Bamfield Marine Sciences Centre, Bamfield, BC, Canada, V0R 1B0
- Institute of Zoology, University of Innsbruck, 6020 Innsbruck, Austria
- Center for Molecular Biosciences, University Innsbruck, 6020 Innsbruck, Austria
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3
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Liu S, Luo L, Zuo F, Huang X, Zhong L, Liu S, Geng Y, Ou Y, Chen D, Cai W, Deng Y. Ammonia nitrogen stress damages the intestinal mucosal barrier of yellow catfish ( Pelteobagrus fulvidraco) and induces intestinal inflammation. Front Physiol 2023; 14:1279051. [PMID: 37791345 PMCID: PMC10542119 DOI: 10.3389/fphys.2023.1279051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 09/04/2023] [Indexed: 10/05/2023] Open
Abstract
Nitrogen from ammonia is one of the most common pollutants toxics to aquatic species in aquatic environment. The intestinal mucosa is one of the key mucosal defenses of aquatic species, and the accumulation of ammonia nitrogen in water environment will cause irreversible damage to intestinal function. In this study, histology, immunohistochemistry, ultrastructural pathology, enzyme activity analysis and qRT-PCR were performed to reveal the toxic effect of ammonia nitrogen stress on the intestine of Pelteobagrus fulvidraco. According to histological findings, ammonia nitrogen stress caused structural damage to the intestine and reduced the number of mucous cells. Enzyme activity analysis revealed that the activity of bactericidal substances (Lysozyme, alkaline phosphatase, and ACP) had decreased. The ultrastructure revealed sparse and shortened microvilli as well as badly degraded tight junctions. Immunohistochemistry for ZO-1 demonstrated an impaired intestinal mucosal barrier. Furthermore, qRT-PCR revealed that tight junction related genes (ZO-1, Occludin, Claudin-1) were downregulated, while the pore-forming protein Claudin-2 was upregulated. Furthermore, as ammonia nitrogen concentration grew, so did the positive signal of Zap-70 (T/NK cell) and the expression of inflammation-related genes (TNF, IL-1β, IL-8, IL-10). In light of the above findings, we conclude that ammonia nitrogen stress damages intestinal mucosal barrier of Pelteobagrus fulvidraco and induces intestinal inflammation.
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Affiliation(s)
- Senyue Liu
- Fisheries Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu, Sichuan, China
- Department of Aquaculture, College of Animal Science & Technology, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Lin Luo
- Department of Aquaculture, College of Animal Science & Technology, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Fengyuan Zuo
- Department of Aquaculture, College of Animal Science & Technology, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Xiaoli Huang
- Department of Aquaculture, College of Animal Science & Technology, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Liang Zhong
- Department of Aquaculture, College of Animal Science & Technology, Sichuan Agricultural University, Chengdu, Sichuan, China
- State Key Lab of Marine Pollution, Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Sha Liu
- Department of Aquaculture, College of Animal Science & Technology, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Yi Geng
- Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Yangping Ou
- Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Defang Chen
- Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Wenlong Cai
- State Key Lab of Marine Pollution, Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Yongqiang Deng
- Fisheries Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu, Sichuan, China
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Jung EH, Nguyen J, Nelson C, Brauner CJ, Wood CM. Ammonia transport is independent of PNH 3 gradients across the gastrointestinal epithelia of the rainbow trout: A role for the stomach. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2023; 339:180-192. [PMID: 36369634 DOI: 10.1002/jez.2670] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 10/01/2022] [Accepted: 10/05/2022] [Indexed: 11/13/2022]
Abstract
Although the gastrointestinal tract (GIT) is an important site for nitrogen metabolism in teleosts, the mechanisms of ammonia absorption and transport remain to be elucidated. Both protein catabolism in the lumen and the metabolism of the GIT tissues produce ammonia which, in part, enters the portal blood through the anterior region of the GIT. The present study examined the possible roles of different GIT sections of rainbow trout (Oncorhynchus mykiss) in transporting ammonia in its unionized gas form-NH3 -by changing the PNH3 gradient across GIT epithelia using in vitro gut sac preparations. We also surveyed messenger RNA expression patterns of three of the identified Rh proteins (Rhbg, Rhcg1, and Rhcg2) as potential NH3 transporters and NKCC as a potential ammonium ion (NH4 + ) transporter along the GIT of rainbow trout. We found that ammonia absorption is not dependent on the PNH3 gradient despite expression of Rhbg and Rhcg2 in the intestinal tissues, and Rhcg2 in the stomach. We detected no expression of Rhbg in the stomach and no expression of Rhcg1 in any GIT tissues. There was also a lack of correlation between ammonia transport and [NH4 + ] gradient despite NKCC expression in all GIT tissues. Regardless of PNH3 gradients, the stomach showed the greatest absorption and net tissue consumption of ammonia. Overall, our findings suggest nitrogen metabolism zonation of GIT, with stomach serving as an important site for the absorption, handling and transport of ammonia that is independent of the PNH3 gradient.
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Affiliation(s)
- Ellen H Jung
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jessica Nguyen
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Charlotte Nelson
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
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Jung EH, Brauner CJ, Wood CM. Do extreme postprandial levels of oxygen, carbon dioxide, and ammonia in the digestive tract equilibrate with the bloodstream in the freshwater rainbow trout (Oncorhynchus mykiss)? J Comp Physiol B 2023; 193:193-205. [PMID: 36656334 DOI: 10.1007/s00360-023-01475-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 12/20/2022] [Accepted: 01/06/2023] [Indexed: 01/20/2023]
Abstract
The gastrointestinal tract (GIT) lumen of teleosts harbors extreme conditions, especially after feeding: high PCO2 (20-115 Torr), total ammonia (415-3710 μM), PNH3 (79-1760 μTorr in the intestine), and virtual anoxia (PO2 < 1 Torr). These levels could be dangerous if they were to equilibrate with the bloodstream. Thus, we investigated the potential equilibration of O2, CO2, and ammonia across the GIT epithelia in freshwater rainbow trout by monitoring postprandial arterial and venous blood gases in vivo and in situ. In vivo blood was sampled from the indwelling catheters in the dorsal aorta (DA) and subintestinal vein (SIV) draining the posterior intestine in the fasting state and at 4 to 48 h following catheter-feeding. To investigate possible ammonia absorption in the anterior part of the GIT, blood was sampled from the DA, SIV and hepatic portal vein (HPV) from anaesthetized fish in situ following voluntary feeding. We found minimal equilibration of all three gases between the GIT lumen and the SIV blood, with the latter maintaining pre-feeding levels (PO2 = 25-49 Torr, PCO2 = 6-8 Torr, and total ammonia = 117-134 μM and PNH3 = 13-30 μTorr at 48 h post-feeding). In contrast to the SIV, we found that the HPV total ammonia more than doubled 24 h after feeding (128 to 297 μM), indicative of absorption in the anterior GIT. Overall, the GIT epithelia of trout, although specialized for absorption, prevent dangerous levels of PO2, PCO2 and ammonia from equilibrating with the blood circulation.
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Affiliation(s)
- Ellen H Jung
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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Jung EH, Brauner CJ, Wood CM. Post-prandial respiratory gas and acid-base profiles in the gastrointestinal tract and its venous drainage in freshwater rainbow trout (Oncorhynchus mykiss) and seawater English sole (Parophrys vetulus). Comp Biochem Physiol A Mol Integr Physiol 2021; 265:111123. [PMID: 34856374 DOI: 10.1016/j.cbpa.2021.111123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 10/15/2021] [Accepted: 11/26/2021] [Indexed: 10/19/2022]
Abstract
The basic respiratory gas and acid-base conditions inside the lumen of the gastrointestinal tract (GIT) and blood draining the tract are largely unestablished in teleost fishes after feeding, though there have been some recent novel discoveries on freshwater rainbow trout (Oncorhynchus mykiss) and seawater English sole (Parophrys vetulus). The present study examined in greater detail the gas (PO2, PCO2, PNH3) and acid-base profiles (pH, [HCO3-], total [ammonia]) in the lumen of the stomach, the anterior, mid, and posterior intestine, as well as the venous drainage (subintestinal and/or hepatic portal vein) of the GIT in these two species 20 h post-feeding. Both species had high PCO2, PNH3, and total [ammonia], and low PO2 (virtual anoxia) in the lumens throughout all sections of the GIT, and high [HCO3-] in the intestine. Total [ammonia], PNH3, and [HCO3-] increased from anterior to posterior intestine in both species. P. vetulus had higher intestinal total [ammonia] and lower [HCO3-] than O. mykiss post feeding, but total [ammonia] was much higher in the stomach of O. mykiss. Despite the extreme conditions in the lumen, both arterial and venous blood showed relatively lower PCO2, total [ammonia] and higher PO2, implying limited equilibration between the two compartments. The higher [HCO3-] and lower total [ammonia] in the intestinal lumen of the freshwater O. mykiss than the seawater P. vetulus suggest the need for future comparative studies using conspecifics fed identical diets but acclimated to the two different salinities in order to understand the potential role of environmental salinity and associated osmoregulatory processes underlying these differences.
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Affiliation(s)
- Ellen H Jung
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada.
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada.
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Jung EH, Smich J, Rubino JG, Wood CM. An in vitro study of urea and ammonia production and transport by the intestinal tract of fed and fasted rainbow trout: responses to luminal glutamine and ammonia loading. J Comp Physiol B 2021; 191:273-287. [PMID: 33415429 DOI: 10.1007/s00360-020-01335-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 11/17/2020] [Accepted: 12/06/2020] [Indexed: 12/28/2022]
Abstract
Digestion of dietary protein in teleosts results in high ammonia levels within the intestinal chyme that may reach concentrations that are many-fold greater than blood plasma levels. We used in vitro gut sac preparations of the ammoniotelic rainbow trout (Oncorhynchus mykiss) to investigate the role of the intestine in producing and transporting ammonia and urea, with specific focus on feeding versus fasting, and on responses to loading of the lumen with 2 mmol L-1 glutamine or 2 mmol L-1 ammonia. Feeding increased not only ammonia production and both mucosal and serosal fluxes, but also increased urea production and serosal fluxes. Elevated urea production was accompanied by an increase in arginase activity but minimal CPS III activity, suggesting that urea may be produced by direct arginolysis. The ammonia production and serosal fluxes increased in fasted preparations with glutamine loading, indicating an ability of the intestinal tissue to deaminate glutamine and perhaps use it as an energy source. However, there was little evidence of urea production or transport resulting from the presence of glutamine. Furthermore, the intestinal tissues did not appear to convert surplus ammonia to urea as a detoxification mechanism, as urea production and serosal flux rates decreased in fed preparations, with minimal changes in fasted preparations. Nevertheless, there was indirect evidence of detoxification by another pathway, as ammonia production rate decreased with ammonia loading in fed preparations. Overall, our study suggests that intestinal tissues of rainbow trout have the ability to produce urea and detoxify ammonia, likely via arginolysis.
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Affiliation(s)
- Ellen H Jung
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada.
| | - Joanna Smich
- Department of Biology, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4K1, Canada.,Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Nowoursynowska 166, 02-787, Warsaw, Poland
| | - Julian G Rubino
- Department of Biology, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4K1, Canada
| | - Chris M Wood
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada.,Department of Biology, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4K1, Canada
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Lim LS, Tan SY, Tuzan AD, Kawamura G, Mustafa S, Rahmah S, Liew HJ. Diel osmorespiration rhythms of juvenile marble goby (Oxyeleotris marmorata). FISH PHYSIOLOGY AND BIOCHEMISTRY 2020; 46:1621-1629. [PMID: 32430644 DOI: 10.1007/s10695-020-00817-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 04/29/2020] [Indexed: 06/11/2023]
Abstract
Oxyeleotris marmorata is an ambush predator. It is known for slow growth rate and high market demand. Farming of O. marmorata still remains a challenge. In order to establish a proper feeding practice to stimulate growth, knowledge of its metabolic processes and cost should be examined. Therefore, this study was designed to investigate the diel osmorespiration rhythms of O. marmorata in response to feeding challenge by using an osmorespirometry assay. The results have shown that oxygen consumption rate of the fed fish was approximately 3 times higher than that of the unfed fish in early evening to support specific dynamic action. Digestion and ingestion processes were likely to be completed within 18-20 h in parallel with the ammonia excretion noticeable in early morning. Under resting metabolism, metabolic oxygen consumption was influenced by diel phase, but no effect was noted in ammonia excretion. As a nocturnal species, O. marmorata exhibited standard aerobic metabolic mode under dark phase followed by light phase, with high oxygen consumption rate found in either fed or unfed fish. It can be confirmed that both the diel phase and feeding have a significant interactive impact on oxygen consumption rate, whereas ammonia metabolism is impacted by feeding state. High metabolic rate of O. marmorata supports the nocturnal foraging activity in this fish. This finding suggested that feeding of O. marmorata should be performed during nighttime and water renewal should be conducted during daytime.
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Affiliation(s)
- Leong-Seng Lim
- Borneo Marine Research Institute, Universiti Malaysia Sabah, Jalan UMS, 88400, Kota Kinabalu, Sabah, Malaysia
| | - Sin-Ying Tan
- Borneo Marine Research Institute, Universiti Malaysia Sabah, Jalan UMS, 88400, Kota Kinabalu, Sabah, Malaysia
| | - Audrey Daning Tuzan
- Borneo Marine Research Institute, Universiti Malaysia Sabah, Jalan UMS, 88400, Kota Kinabalu, Sabah, Malaysia
| | - Gunzo Kawamura
- Borneo Marine Research Institute, Universiti Malaysia Sabah, Jalan UMS, 88400, Kota Kinabalu, Sabah, Malaysia
| | - Saleem Mustafa
- Borneo Marine Research Institute, Universiti Malaysia Sabah, Jalan UMS, 88400, Kota Kinabalu, Sabah, Malaysia
| | - Sharifah Rahmah
- Institute of Tropical Aquaculture and Fisheries, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia
- Faculty of Fisheries and Food Science, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia
| | - Hon Jung Liew
- Institute of Tropical Aquaculture and Fisheries, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia.
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Liew HJ, Pelle A, Chiarella D, Faggio C, Tang CH, Blust R, De Boeck G. Common carp, Cyprinus carpio, prefer branchial ionoregulation at high feeding rates and kidney ionoregulation when food supply is limited: additional effects of cortisol and exercise. FISH PHYSIOLOGY AND BIOCHEMISTRY 2020; 46:451-469. [PMID: 31773438 DOI: 10.1007/s10695-019-00736-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 11/13/2019] [Indexed: 06/10/2023]
Abstract
This study aims to examine ionoregulatory parameters during exercise and cortisol elevation in common carp fed different food rations. Fish subjected to two different feeding regimes (0.5 or 3.0% body mass (BM) daily) received no implant or an intraperitoneal cortisol implant (250 mg/kg BM) or sham, and were monitored over a 168-h post-implant (PI) period under resting, low aerobic swimming or exhaustive swimming conditions. Plasma osmolality was maintained at relatively stable levels without much influence of feeding, swimming or cortisol, especially in low feeding groups. Nevertheless, a transient hyponatremia was observed in all low feeding fish implanted with cortisol. The hyponatremia was more pronounced in fish swum to exhaustion but even in this group, Na+ levels returned to control levels as cortisol levels recovered (168 h-PI). Cortisol-implanted fish also had lower plasma Cl- levels, and this loss of plasma Cl- was more prominent in fish fed a high ration during exhaustive swimming (recovered at 168 h-PI). Cortisol stimulated branchial NKA and H+ ATPase activities, especially in high ration fish. In contrast, low ration fish upregulated kidney NKA and H+ ATPase activities when experiencing elevated levels of cortisol. In conclusion, low feeding fish experience an ionoregulatory disturbance in response to cortisol implantation especially when swum to exhaustion in contrast to high feeding fish.
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Affiliation(s)
- Hon Jung Liew
- Institute of Tropical Aquaculture and Fisheries, Universiti Malaysia Terengganu, 21030, Kuala Terengganu, Terengganu, Malaysia.
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020, Antwerp, Belgium.
| | - Antonella Pelle
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020, Antwerp, Belgium
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres, 31 CAP, 98166, Messina, Italy
| | - Daniela Chiarella
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020, Antwerp, Belgium
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres, 31 CAP, 98166, Messina, Italy
| | - Caterina Faggio
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres, 31 CAP, 98166, Messina, Italy
| | - Cheng-Hao Tang
- Department of Oceanography, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan, Republic of China
| | - Ronny Blust
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020, Antwerp, Belgium
| | - Gudrun De Boeck
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020, Antwerp, Belgium
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Turner LA, Bucking C. The role of intestinal bacteria in the ammonia detoxification ability of teleost fish. ACTA ACUST UNITED AC 2019; 222:jeb.209882. [PMID: 31753905 DOI: 10.1242/jeb.209882] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 11/13/2019] [Indexed: 12/23/2022]
Abstract
Protein catabolism during digestion generates appreciable levels of ammonia in the gastrointestinal tract (GIT) lumen. Amelioration by the enterocyte, via enzymes such as glutamine synthetase (GS), glutamate dehydrogenase (GDH), and alanine and aspartate aminotransferases (ALT; AST), is found in teleost fish. Conservation of these enzymes across bacterial phyla suggests that the GIT microbiome could also contribute to ammonia detoxification by providing supplemental activity. Hence, the GIT microbiome, enzyme activities and ammonia detoxification were investigated in two fish occupying dissimilar niches: the carnivorous rainbow darter and the algivorous central stoneroller. There was a strong effect of fish species on the activity levels of GS, GDH, AST and ALT, as well as GIT lumen ammonia concentration, and bacterial composition of the GIT microbiome. Furthermore, removal of the intestinal bacteria impacted intestinal activities of GS and ALT in the herbivorous fish but not in the carnivore. The repeatability and robustness of this relationship was tested across field locations and years. Within an individual waterbody, there was no impact of sampling location on any of these factors. However, different waterbodies affected enzyme activities and luminal ammonia concentrations in both fish, while only the central stoneroller intestinal bacteria populations varied. Overall, a relationship between GIT bacteria, enzyme activity and ammonia detoxification was observed in herbivorous fish while the carnivorous fish displayed a correlation between enzyme activity and ammonia detoxification alone that was independent of the GIT microbiome. This could suggest that carnivorous fish are less dependent on non-host mechanisms for ammonia regulation in the GIT.
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Affiliation(s)
- Leah A Turner
- Department of Biology, York University, 4700 Keele St, Toronto, ON M3J 1P3, Canada
| | - Carol Bucking
- Department of Biology, York University, 4700 Keele St, Toronto, ON M3J 1P3, Canada
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An in vitro analysis of intestinal ammonia transport in fasted and fed freshwater rainbow trout: roles of NKCC, K + channels, and Na +, K + ATPase. J Comp Physiol B 2019; 189:549-566. [PMID: 31486919 DOI: 10.1007/s00360-019-01231-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 07/15/2019] [Accepted: 08/21/2019] [Indexed: 12/20/2022]
Abstract
We examined mechanisms of ammonia handling in the anterior, mid, and posterior intestine of unfed and fed freshwater rainbow trout (Oncorhynchus mykiss), with a focus on the Na+:K+:2Cl- co-transporter (NKCC), Na+:K +-ATPase (NKA), and K+ channels. NKCC was localized by immunohistochemistry to the mucosal (apical) surface of enterocytes, and NKCC mRNA was upregulated after feeding in the anterior and posterior segments. NH4+ was equally potent to K+ in supporting NKA activity in all intestinal sections. In vitro gut sac preparations were employed to examine mucosal ammonia flux rates (Jmamm, disappearance from the mucosal saline), serosal ammonia flux rates (Jsamm, appearance in the serosal saline), and total tissue ammonia production rates (Jtamm = Jsamm - Jmamm). Bumetanide (10-4 mol L-1), a blocker of NKCC, inhibited Jsamm in most preparations, but this was largely due to reduction of Jtamm; Jmamm was significantly inhibited only in the anterior intestine of fed animals. Ouabain (10-4 mol L-1), a blocker of NKA, generally reduced both Jmamm and Jsamm without effects on Jtamm in most preparations, though the anterior intestine was resistant after feeding. Barium (10-2 mol L-1), a blocker of K+ channels, inhibited Jmamm in most preparations, and Jsamm in some, without effects on Jtamm. These pharmacological results, together with responses to manipulations of serosal and mucosal Na+ and K+ concentrations, suggest that NKCC is not as important in ammonia absorption as previously believed. NH4+ appears to be taken up through barium-sensitive K+ channels on the mucosal surface. Mucosal NH4+ uptake via both NKCC and K+ channels is energized by basolateral NKA, which plays an additional role in scavenging NH4+ on the serosal surface to possibly minimize blood toxicity or enhance ion uptake and amino acid synthesis following feeding. Together with recent findings from other studies, we have provided an updated model to describe the current understanding of intestinal ammonia transport in teleost fish.
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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.
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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
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Wood CM, Liew HJ, De Boeck G, Hoogenboom JL, Anderson WG. Nitrogen handling in the elasmobranch gut: a role for microbial urease. ACTA ACUST UNITED AC 2019; 222:jeb.194787. [PMID: 30530835 DOI: 10.1242/jeb.194787] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 12/03/2018] [Indexed: 11/20/2022]
Abstract
Ureotelic elasmobranchs require nitrogen for both protein growth and urea-based osmoregulation, and therefore are probably nitrogen-limited in nature. Mechanisms exist for retaining and/or scavenging nitrogen in the gills, kidney, rectal gland and gut, but as yet, the latter are not well characterized. Intestinal sac preparations of the Pacific spiny dogfish shark (Squalus acanthias suckleyi) incubated in vitro strongly reabsorbed urea from the lumen after feeding, but mucosal fluid ammonia concentrations increased with incubation time. Phloretin (0.25 mmol l-1, which blocked urea reabsorption) greatly increased the rate of ammonia accumulation in the lumen. A sensitive [14C]urea-based assay was developed to examine the potential role of microbial urease in this ammonia production. Urease activity was detected in chyme/intestinal fluid and intestinal epithelial tissue of both fed and fasted sharks. Urease was not present in gall-bladder bile. Urease activities were highly variable among animals, but generally greater in chyme than in epithelia, and greater in fed than in fasted sharks. Comparable urease activities were found in chyme and epithelia of the Pacific spotted ratfish (Hydrolagus colliei), a ureotelic holocephalan, but were much lower in ammonotelic teleosts. Urease activity in dogfish chyme was inhibited by acetohydroxamic acid (1 mmol l-1) and by boiling. Treatment of dogfish gut sac preparations with acetohydroxamic acid blocked ammonia production, changing net ammonia accumulation into net ammonia absorption. We propose that microbial urease plays an important role in nitrogen handling in the elasmobranch intestine, allowing some urea-N to be converted to ammonia, which is then reabsorbed for amino acid synthesis or reconversion to urea.
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Affiliation(s)
- Chris M Wood
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC V0R 1B0, Canada .,Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.,Department of Biology, McMaster University, 1280 Main St. West, Hamilton, ON L8S 4K1, Canada
| | - Hon Jung Liew
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC V0R 1B0, Canada.,Institute of Tropical Aquaculture, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia
| | - Gudrun De Boeck
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC V0R 1B0, Canada.,Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium
| | - J Lisa Hoogenboom
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC V0R 1B0, Canada.,Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada R3T 2N2
| | - W Gary Anderson
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC V0R 1B0, Canada.,Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada R3T 2N2
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Fehsenfeld S, Wood CM. Section-specific expression of acid-base and ammonia transporters in the kidney tubules of the goldfish Carassius auratus and their responses to feeding. Am J Physiol Renal Physiol 2018; 315:F1565-F1582. [PMID: 30089033 DOI: 10.1152/ajprenal.00510.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In teleost fishes, renal contributions to acid-base and ammonia regulation are often neglected compared with the gills. In goldfish, increased renal acid excretion in response to feeding was indicated by increased urine ammonia and inorganic phosphate concentrations and decreased urine pH. By microdissecting the kidney tubules and performing quantitative real-time PCR and/or immunohistochemistry, we profiled the section-specific expression of glutamate dehydrogenase (GDH), glutamine synthetase (GS), Na+/H+-exchanger 3 (NHE3), carbonic anhydrase II (CAIIa), V-H+-ATPase subunit 1b, Cl-/ HCO3- -exchanger 1 (AE1), Na+/ HCO3- -cotransporter 1 (NBC1), Na+/K+-ATPase subunit 1α, and Rhesus-proteins Rhbg, Rhcg1a, and Rhcg1b. Here, we show for the first time that 1) the proximal tubule appears to be the major site for ammoniagenesis, 2) epithelial transporters are differentially expressed along the renal tubule, and 3) a potential feeding-related "acidic tide" results in the differential regulation of epithelial transporters, resembling the mammalian renal response to a metabolic acidosis. Specifically, GDH and NHE3 mRNAs were upregulated and GS downregulated in the proximal tubule upon feeding, suggesting this section as a major site for ammoniagenesis and acid secretion. The distal tubule may play a major role in renal ammonia secretion, with feeding-induced upregulation of mRNA and protein for apical NHE3, cytoplasmic CAIIa, universal Rhcg1a and apical Rhcg1b, and downregulation of basolateral Rhbg and AE1. Changes in mRNA expression of the Wolffian ducts and bladder suggest supporting roles in fine-tuning urine composition. The present study verifies an important renal contribution to acid-base balance and emphasizes that studies looking at the whole kidney may overlook key section-specific responses.
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Affiliation(s)
- Sandra Fehsenfeld
- University of British Columbia, Department of Zoology , Vancouver , Canada
| | - Chris M Wood
- University of British Columbia, Department of Zoology , Vancouver , Canada
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Hu R, Qu F, Tang J, Zhao Q, Yan J, Zhou Z, Zhou Y, Liu Z. Cloning, expression, and nutritional regulation of the glutamine synthetase gene in Ctenopharyngodon idellus. Comp Biochem Physiol B Biochem Mol Biol 2017. [DOI: 10.1016/j.cbpb.2017.06.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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16
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Turner LA, Bucking C. The interactive effect of digesting a meal and thermal acclimation on maximal enzyme activities in the gill, kidney, and intestine of goldfish (Carassius auratus). J Comp Physiol B 2017; 187:959-972. [PMID: 28382530 DOI: 10.1007/s00360-017-1068-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 02/08/2017] [Accepted: 02/21/2017] [Indexed: 11/30/2022]
Abstract
Surrounding environmental temperatures affect many aspects of ectotherm physiology. Generally, organisms can compensate at one or more biological levels, or allow temperature to dictate processes such as enzyme activities through kinetic effects on reaction rates. As digestion also alters physiological processes such as enzyme activities, this study determined the interacting effect of thermal acclimation (8 and 20 °C) and digesting a single meal on maximal enzyme activities in three tissues of the goldfish (Carrassius auratus). Acclimation to elevated temperatures decreased branchial Na+, K+, ATPase (NKA) activity. In contrast, acclimation to elevated temperatures had no effect on citrate synthase (CS) or pyruvate kinase (PK) activity in any tissue, nor were renal NKA or glutamine synthetase (GS) activities impacted. Warm water-acclimation exaggerated the positive impact of digestion on intestinal and branchial NKA activities and intestinal GS activity only, but digestion had no effect in the kidney. CS and PK did not display intestinal zonation; however, there was a distinct increase towards the distal intestine in NKA and GS activities. Zonation of NKA was more prominent in warm-acclimated animals, while acclimation temperature did not affect intestinal heterogeneity of GS. Finally, the impact of tissue protein content on enzyme activity was discussed. We conclude that the intestine and gill of warm-acclimated goldfish exhibited an augmented capacity for increasing several enzyme activities in response to digestion while the kidney was unaffected by thermal acclimation or digesting a single meal. However, this amplified capacity was ameliorated by alterations in tissue protein content. Amplified increases in NKA activity may ultimately have implications for ATP demand in these tissues, while increased GS activity may beneficially increase ammonia-detoxifying capacity in the intestine.
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Affiliation(s)
- Leah A Turner
- Department of Biology, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
| | - Carol Bucking
- Department of Biology, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
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17
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Bucking C. A broader look at ammonia production, excretion, and transport in fish: a review of impacts of feeding and the environment. J Comp Physiol B 2016; 187:1-18. [PMID: 27522221 DOI: 10.1007/s00360-016-1026-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 07/22/2016] [Accepted: 07/29/2016] [Indexed: 12/23/2022]
Abstract
For nearly a century, researchers have studied ammonia production and excretion in teleost fish. Stemming from past investigations a body of knowledge now exists on various aspects including biochemical mechanisms of ammonia formation and specific routes and tissues used for ammonia transport, culminating in a current detailed theoretical model of branchial transport, including the molecular identities of the moieties involved. However, typical studies examining ammonia balance use routine laboratory conditions and fasted fish. While avoiding additional variables that influence nitrogen balance, these studies are arguably idealistic and do not reflect the natural variety of conditions that fish encounter. Further studies have revealed the impacts of extrinsic factors (e.g. salinity, pH, temperature) on ammonia handling in fasted fish whereas others have explored intrinsic factors, such as life history and developmental impacts. One routine challenge for ammonia balance that fish encounter is feeding and digestion. Fortunately, many new studies have revealed the impact of feeding and digestion on several aspects of ammonia balance; from production to excretion and to transport, and several have done so incorporating supplemental extrinsic and/or intrinsic factors. Together, these complex studies reveal realistic responses to multifactorial challenges encountered by animals in the wild and begin to provide a holistic view of ammonia balance in freshwater teleost fish.
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Affiliation(s)
- Carol Bucking
- Department of Biology, Farquharson Life Science Building, York University, Toronto, ON, M3J 1P3, Canada.
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18
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Rubino JG, Zimmer AM, Wood CM. Intestinal ammonia transport in freshwater and seawater acclimated rainbow trout (Oncorhynchus mykiss): evidence for a Na+ coupled uptake mechanism. Comp Biochem Physiol A Mol Integr Physiol 2014; 183:45-56. [PMID: 25545914 DOI: 10.1016/j.cbpa.2014.12.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Revised: 12/17/2014] [Accepted: 12/19/2014] [Indexed: 12/23/2022]
Abstract
In vitro gut sac experiments were performed on freshwater and 60% seawater acclimated trout (Oncorhynchus mykiss) under treatments designed to discern possible mechanisms of intestinal ammonia transport. Seawater acclimation increased ammonia flux rate into the serosal saline (Jsamm) in the anterior intestine, however it did not alter Jsamm in the mid- or posterior intestine suggesting similar mechanisms of ammonia handling in freshwater and seawater fish. Both fluid transport rate (FTR) and Jsamm were inhibited in response to basolateral ouabain treatment, suggesting a linkage of ammonia uptake to active transport, possibly coupled to fluid transport processes via solvent drag. Furthermore, decreases in FTR and Jsamm caused by low Na(+) treatment indicated a Na(+) linked transport mechanism. Mucosal bumetanide (10(-4) M) had no impact on FTR, yet decreased Jsamm in the anterior and mid-intestine, suggesting NH4(+) substitution for K(+) on an apical NKCC, and at least a partial uncoupling of ammonia transport from fluid transport. Additional treatments (amiloride, 5-(N-ethyl-N-isopropyl)amiloride (EIPA), phenamil, bafilomycin, 4',6-diamidino-2-phenylindole (DAPI), high sodium) intended to disrupt alternative routes of Na(+) uptake yielded no change in FTR or Jsamm, suggesting the absence of direct competition between Na(+) and ammonia for transport. Finally, [(14)C]methylamine permeability (PMA) measurements indicated the likely presence of an intestinal Rh-mediated ammonia transport system, as increasing NH4Cl (0, 1, 5 mmol l(-1)) concentrations reduced PMA, suggesting competition for transport through Rh proteins. Overall, the data presented in this paper provide some of the first insights into mechanisms of teleost intestinal ammonia transport.
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Affiliation(s)
- Julian G Rubino
- McMaster University, Life Sciences Building, Department of Biology, Hamilton, Ontario L8S 4K1, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada.
| | - Alex M Zimmer
- McMaster University, Life Sciences Building, Department of Biology, Hamilton, Ontario L8S 4K1, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada
| | - Chris M Wood
- McMaster University, Life Sciences Building, Department of Biology, Hamilton, Ontario L8S 4K1, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada; Dept. of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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19
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Pelster B, Wood CM, Speers-Roesch B, Driedzic WR, Almeida-Val V, Val A. Gut transport characteristics in herbivorous and carnivorous serrasalmid fish from ion-poor Rio Negro water. J Comp Physiol B 2014; 185:225-41. [DOI: 10.1007/s00360-014-0879-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 11/11/2014] [Accepted: 11/22/2014] [Indexed: 10/24/2022]
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20
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Nadella SR, Patel D, Ng A, Wood CM. An in vitro investigation of gastrointestinal Na(+) uptake mechanisms in freshwater rainbow trout. J Comp Physiol B 2014; 184:1003-19. [PMID: 25183198 DOI: 10.1007/s00360-014-0855-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 07/30/2014] [Accepted: 08/05/2014] [Indexed: 11/28/2022]
Abstract
In vitro gut-sac preparations of all four sections (stomach, anterior, mid, and posterior intestine) of the gastrointestinal tract (GIT) of freshwater rainbow trout, together with radiotracer ((22)Na) techniques, were used to study unidirectional Na(+) uptake rates (UR, mucosal → blood space) and net absorptive fluid transport rates (FTR) under isosmotic conditions (mucosal = serosal osmolality). On an area-specific basis, unidirectional Na(+) UR was highest in the mid-intestine, but when total gut area was taken into account, the three intestinal sections contributed equally, with very low rates in the stomach. The theoretical capacity for Na(+) uptake across the whole GIT is sufficient to supply all of the animal's nutritive requirements for Na(+). Transport occurs by low affinity systems with apparent K m values 2-3 orders of magnitude higher than those in the gills, in accord with comparably higher Na(+) concentrations in chyme versus fresh water. Fluid transport appeared to be Na(+)-dependent, such that treatments which altered unidirectional Na(+) UR generally altered FTR in a comparable fashion. Pharmacological trials (amiloride, EIPA, phenamil, bafilomycin, furosemide, hydrochlorothiazide) conducted at a mucosal Na(+) concentration of 50 mmol L(-1) indicated that GIT Na(+) uptake occurs by a variety of apical mechanisms (NHE, Na(+) channel/H(+) ATPase, NCC, NKCC) with relative contributions varying among sections. However, at a mucosal Na(+) concentration of 10 mmol L(-1), EIPA, phenamil, bafilomycin, and hydrochlorothiazide were no longer effective in inhibiting unidirectional Na(+) UR or FTR, suggesting the contribution of unidentified mechanisms under low Na(+) conditions. A preliminary model is presented.
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Affiliation(s)
- Sunita R Nadella
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, L8S4K1, Canada,
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Wood CM, Nawata CM, Wilson JM, Laurent P, Chevalier C, Bergman HL, Bianchini A, Maina JN, Johannsson OE, Bianchini LF, Kavembe GD, Papah MB, Ojoo RO. Rh proteins and NH4(+)-activated Na+-ATPase in the Magadi tilapia (Alcolapia grahami), a 100% ureotelic teleost fish. ACTA ACUST UNITED AC 2014; 216:2998-3007. [PMID: 23885087 DOI: 10.1242/jeb.078634] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The small cichlid fish Alcolapia grahami lives in Lake Magadi, Kenya, one of the most extreme aquatic environments on Earth (pH ~10, carbonate alkalinity ~300 mequiv l(-1)). The Magadi tilapia is the only 100% ureotelic teleost; it normally excretes no ammonia. This is interpreted as an evolutionary adaptation to overcome the near impossibility of sustaining an NH3 diffusion gradient across the gills against the high external pH. In standard ammoniotelic teleosts, branchial ammonia excretion is facilitated by Rh glycoproteins, and cortisol plays a role in upregulating these carriers, together with other components of a transport metabolon, so as to actively excrete ammonia during high environmental ammonia (HEA) exposure. In Magadi tilapia, we show that at least three Rh proteins (Rhag, Rhbg and Rhcg2) are expressed at the mRNA level in various tissues, and are recognized in the gills by specific antibodies. During HEA exposure, plasma ammonia levels and urea excretion rates increase markedly, and mRNA expression for the branchial urea transporter mtUT is elevated. Plasma cortisol increases and branchial mRNAs for Rhbg, Rhcg2 and Na(+),K(+)-ATPase are all upregulated. Enzymatic activity of the latter is activated preferentially by NH4(+) (versus K(+)), suggesting it can function as an NH4(+)-transporter. Model calculations suggest that active ammonia excretion against the gradient may become possible through a combination of Rh protein and NH4(+)-activated Na(+)-ATPase function.
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Affiliation(s)
- Chris M Wood
- Department of Biology, McMaster University, Hamilton, ON, Canada.
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Chinigarzadeh A, Kasim NF, Muniandy S, Kassim NM, Salleh N. Genistein induces increase in fluid pH, Na+ and HCO3(-) concentration, SLC26A6 and SLC4A4 (NBCe1)-B expression in the uteri of ovariectomized rats. Int J Mol Sci 2014; 15:958-76. [PMID: 24434640 PMCID: PMC3907849 DOI: 10.3390/ijms15010958] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Revised: 12/08/2013] [Accepted: 12/29/2013] [Indexed: 12/25/2022] Open
Abstract
Genistein has been reported to stimulate luminal HCO3− secretion. We hypothesized that genistein mediates this effect via SLC26A6 and SLC4A4 (NBCe1) transporters. Our study aimed to: investigate changes in uterine fluid pH, Na+ and HCO3− concentration and expression of uterine SLC26A6 and NBCe1 under genistein effect. Ovariectomized adult female rats received 25, 50 and 100 mg/kg/day genistein for a week with and without ICI 182780. A day after the last injection, in vivo uterine perfusion was performed to collect uterine fluid for Na+, HCO3− and pH determination. The animals were then sacrificed and uteri were removed for mRNA and protein expression analyses. SLC26A6 and NBCe1-A and NBCe1-B distribution were visualized by immunohistochemistry (IHC). Genistein at 50 and 100 mg/kg/day stimulates uterine fluid pH, Na+ and HCO3− concentration increase. Genistein at 100 mg/kg/day up-regulates the expression of SLC26A6 and SLC4A4 mRNA, which were reduced following concomitant ICI 182780 administration. In parallel, SLC26A6 and NBCe1-B protein expression were also increased following high dose genistein treatment and were localized mainly at the apical membrane of the luminal epithelia. SLC26A6 and NBCe1-B up-regulation by genistein could be responsible for the observed increase in the uterine fluid pH, Na+ and HCO3− concentration under this condition.
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Affiliation(s)
- Asma Chinigarzadeh
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur 50603, Malaysia.
| | - Nor Fadila Kasim
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur 50603, Malaysia.
| | - Sekaran Muniandy
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur 50603, Malaysia.
| | - Normadiah M Kassim
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur 50603, Malaysia.
| | - Naguib Salleh
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur 50603, Malaysia.
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Rubino JG, Zimmer AM, Wood CM. An in vitro analysis of intestinal ammonia handling in fasted and fed freshwater rainbow trout (Oncorhynchus mykiss). J Comp Physiol B 2013; 184:91-105. [PMID: 24043214 DOI: 10.1007/s00360-013-0781-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 08/23/2013] [Accepted: 08/27/2013] [Indexed: 11/30/2022]
Abstract
Ammonia transport and metabolism were investigated in the intestinal tract of freshwater rainbow trout which had been either fasted for 7 days, or fasted then fed a satiating meal of commercial trout pellets. In vivo, total ammonia concentrations (T amm) in the chyme were approximately 1 mmol L(-1) across the entire intestine at 24 h after the meal. Highest chyme pH and P NH3 values occurred in the posterior intestine. In vitro gut sac experiments examined ammonia handling with mucosal (Jmamm) and serosal (Js amm) fluxes under conditions of fasting and feeding, with either background (control ≤ 0.013 mmol L(-1)) or high luminal ammonia concentrations (HLA = 1 mmol L(-1)), the latter mimicking those seen in chyme in vivo. Feeding status (fasted or fed) appeared to influence ammonia handling by each individual section. The anterior intestine exhibited the greatest Jm amm and Js amm values under fasted control conditions, but these differences tended to disappear under typical post-feeding conditions when total endogenous ammonia production (Jt amm = Js amm - Jm amm, signs considered) was greatly elevated in all intestinal sections. Under fasted conditions, glutamate dehydrogenase (GDH) and glutaminase (GLN) activities were equal across all sections, but the ammonia-trapping enzyme glutamine synthetase (GS) exhibited highest activity in the posterior intestine, in contradiction to previous literature. Feeding clearly stimulated the total rate of endogenous ammonia production (Jt amm), even in the absence of a high luminal ammonia load. This was accompanied by an increase in GDH activity of the anterior intestine, which was also the site of the largest Jt amm. In all sections, during HLA exposure, either alone or in combination with feeding, there were much larger increases in endogenous Jt amm, most of which was effluxed to the serosal solution. This is interpreted as a response to avoid potential cytotoxicity due to overburdened detoxification mechanisms in the face of elevated mucosal ammonia. Thus T amm of the intestinal tissue remained relatively constant regardless of feeding status and exposure to HLA. Ammonia production by the gut may explain up to 18 % of whole-body ammonia excretion in vivo under fasting conditions, and 47 % after feeding, of which more than half originates from endogenous production rather than from absorption from the lumen.
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Affiliation(s)
- Julian G Rubino
- Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada,
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Bucking C, Edwards SL, Tickle P, Smith CP, McDonald MD, Walsh PJ. Immunohistochemical localization of urea and ammonia transporters in two confamilial fish species, the ureotelic gulf toadfish (Opsanus beta) and the ammoniotelic plainfin midshipman (Porichthys notatus). Cell Tissue Res 2013; 352:623-37. [PMID: 23512140 DOI: 10.1007/s00441-013-1591-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 02/14/2013] [Indexed: 12/29/2022]
Abstract
This study aims to illustrate potential transport mechanisms behind the divergent approaches to nitrogen excretion seen in the ureotelic toadfish (Opsanus beta) and the ammoniotelic plainfin midshipman (Porichthys notatus). Specifically, we wish to confirm the expression of a urea transporter (UT), which is found in the gill of the toadfish and which is responsible for the unique "pulsing" nature of urea excretion and to localize the transporter within specific gill cells and at specific cellular locations. Additionally, the localization of ammonia transporters (Rhesus glycoproteins; Rhs) within the gill of both the toadfish and midshipman was explored. Toadfish UT (tUT) was found within Na(+)-K(+)-ATPase (NKA)-enriched cells, i.e., ionocytes (probably mitochondria-rich cells), especially along the basolateral membrane and potentially on the apical membrane. In contrast, midshipman UT (pnUT) immunoreactivity did not colocalize with NKA immunoreactivity and was not found along the filaments but instead within the lamellae. The cellular location of Rh proteins was also dissimilar between the two fish species. In toadfish gills, the Rh isoform Rhcg1 was expressed in both NKA-reactive cells and non-reactive cells, whereas Rhbg and Rhcg2 were only expressed in the latter. In contrast, Rhbg, Rhcg1 and Rhcg2 were expressed in both NKA-reactive and non-reactive cells of midshipman gills. In an additional transport epithelium, namely the intestine, the expression of both UTs and Rhs was similar between the two species, with only subtle differences being observed.
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Affiliation(s)
- Carol Bucking
- Department of Biology, University of Ottawa, Ottawa, ON, Canada.
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Bucking C, LeMoine CMR, Craig PM, Walsh PJ. Nitrogen metabolism of the intestine during digestion in a teleost fish, the plainfin midshipman (Porichthys notatus). ACTA ACUST UNITED AC 2013; 216:2821-32. [PMID: 23619402 DOI: 10.1242/jeb.081562] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Digestion affects nitrogen metabolism in fish, as both exogenous and endogenous proteins and amino acids are catabolized, liberating ammonia in the process. Here we present a model of local detoxification of ammonia by the intestinal tissue of the plainfin midshipman (Porichthys notatus) during digestion, resulting in an increase in urea excretion of gastrointestinal origin. Corroborating evidence indicated whole-animal ammonia and urea excretion increased following feeding, and ammonia levels within the lumen of the midshipman intestine increased to high levels (1.8±0.4 μmol N g(-1)). We propose that this ammonia entered the enterocytes and was detoxified to urea via the ornithine-urea cycle (O-UC) enzymes, as evidenced by a 1.5- to 2.9-fold post-prandial increase in glutamine synthetase activity (0.14±0.05 and 0.28±0.02 μmol min(-1) g(-1) versus 0.41±0.03 μmol min(-1) g(-1)) and an 8.7-fold increase in carbamoyl phosphate synthetase III activity (0.3±1.2 versus 2.6±0.4 nmol min(-1) g(-1)). Furthermore, digestion increased urea production by isolated gastrointestinal tissue 1.7-fold, supporting our hypothesis that intestinal tissue synthesizes urea in response to feeding. We further propose that the intestinal urea may have been excreted into the intestinal lumen via an apical urea transporter as visualized using immunohistochemistry. A portion of the urea was then excreted to the environment along with the feces, resulting in the observed increase in urea excretion, while another portion may have been used by intestinal ureolytic bacteria. Overall, we propose that P. notatus produces urea within the enterocytes via a functional O-UC, which is then excreted into the intestinal lumen. Our model of intestinal nitrogen metabolism does not appear to be universal as we were unab le to activate the O-UC in the intestine of fed rainbow trout. However, literature values suggest that multiple fish species could follow this model.
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Affiliation(s)
- Carol Bucking
- Department of Biology, University of Ottawa, ON, Canada and Bamfield Marine Science Center, Bamfield, BC, Canada.
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