1
|
Zhao XF, Huang J, Li W, Wang SY, Liang LQ, Zhang LM, Liew HJ, Chang YM. Rh proteins and H + transporters involved in ammonia excretion in Amur Ide (Leuciscus waleckii) under high alkali exposure. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 273:116160. [PMID: 38432157 DOI: 10.1016/j.ecoenv.2024.116160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 02/22/2024] [Accepted: 02/25/2024] [Indexed: 03/05/2024]
Abstract
High alkaline environment can lead to respiratory alkalosis and ammonia toxification to freshwater fish. However, the Amur ide (Leuciscus waleckii), which inhabits an extremely alkaline lake in China with titratable alkalinity up to 53.57 mM (pH 9.6) has developed special physiological and molecular mechanisms to adapt to such an environment. Nevertheless, how the Amur ide can maintain acid-base balance and perform ammonia detoxification effectively remains unclear. Therefore, this study was designed to study the ammonia excretion rate (Tamm), total nitrogen accumulation in blood and tissues, including identification, expression, and localization of ammonia-related transporters in gills of both the alkali and freshwater forms of the Amur ide. The results showed that the freshwater form Amur ide does not have a perfect ammonia excretion mechanism exposed to high-alkaline condition. Nevertheless, the alkali form of Amur ide was able to excrete ammonia better than freshwater from Amur ide, which was facilitated by the ionocytes transporters (Rhbg, Rhcg1, Na+/H+ exchanger 2 (NHE2), and V-type H+ ATPase (VHA)) in the gills. Converting ammonia into urea served as an ammonia detoxication strategy to reduced endogenous ammonia accumulation under high-alkaline environment.
Collapse
Affiliation(s)
- Xue Fei Zhao
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China; College of Wildlife and Protected Area, Northeast Forestry University, Harbin 150040, China
| | - Jing Huang
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China
| | - Wen Li
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 2000, China
| | - Shuang Yi Wang
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China; BGI Genomics, BGI-Shenzhen, Shenzhen, Guangdong 518083, China
| | - Li Qun Liang
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China
| | - Li Min Zhang
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China
| | - Hon Jung Liew
- Higher Institution Center of Excellence (HICoE), Institute of Tropical Aquaculture and Fisheries, Universiti of Malaysia Terengganu, Kuala Nerus, Terengganu 21030, Malaysia
| | - Yu Mei Chang
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China.
| |
Collapse
|
2
|
Marina G, Glover CN, Goss GG, Zimmer AM. The skin of adult rainbow trout is not a significant site of ammonia clearance from the blood. JOURNAL OF FISH BIOLOGY 2021; 99:1529-1534. [PMID: 34159596 DOI: 10.1111/jfb.14831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 05/14/2021] [Accepted: 06/17/2021] [Indexed: 06/13/2023]
Abstract
We hypothesized that the skin acts as an extrabranchial route for ammonia excretion in adult rainbow trout (Oncorhynchus mykiss) following high environmental ammonia (HEA) exposure. Trunks of control or HEA-exposed trout were perfused with saline containing 0 or 1 mmol l-1 NH4 + . Cutaneous ammonia excretion rates increased 2.5-fold following HEA exposure, however there was no difference in rates between trunks perfused with 0 or 1 mmol l-1 NH4 + . The skin is therefore capable of excreting its own ammonia load, but it does not clear circulating ammonia from the plasma.
Collapse
Affiliation(s)
- Giacomin Marina
- Department of Biological Sciences, CW 405, Biological Sciences Bldg, University of Alberta, Edmonton, Alberta, Canada
| | - Chris N Glover
- Department of Biological Sciences, CW 405, Biological Sciences Bldg, University of Alberta, Edmonton, Alberta, Canada
- Faculty of Science and Technology and Athabasca River Basin Research Institute, Athabasca University, Athabasca, Alberta, Canada
| | - Greg G Goss
- Department of Biological Sciences, CW 405, Biological Sciences Bldg, University of Alberta, Edmonton, Alberta, Canada
| | - Alex M Zimmer
- Department of Biological Sciences, CW 405, Biological Sciences Bldg, University of Alberta, Edmonton, Alberta, Canada
| |
Collapse
|
3
|
Eom J, Giacomin M, Clifford AM, Goss GG, Wood CM. Ventilatory sensitivity to ammonia in the Pacific hagfish ( Eptatretus stoutii), a representative of the oldest extant connection to the ancestral vertebrates. ACTA ACUST UNITED AC 2019; 222:jeb.199794. [PMID: 31221739 DOI: 10.1242/jeb.199794] [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: 01/16/2019] [Accepted: 06/16/2019] [Indexed: 12/30/2022]
Abstract
Ventilatory sensitivity to ammonia occurs in teleosts, elasmobranchs and mammals. Here, we investigated whether the response is also present in hagfish. Ventilatory parameters (nostril flow, pressure amplitude, velar frequency and ventilatory index, the last representing the product of pressure amplitude and frequency), together with blood and water chemistry, were measured in hagfish exposed to either high environmental ammonia (HEA) in the external sea water or internal ammonia loading by intra-vascular injection. HEA exposure (10 mmol l-1 NH4HCO3 or 10 mmol l-1 NH4Cl) caused a persistent hyperventilation by 3 h, but further detailed analysis of the NH4HCO3 response showed that initially (within 5 min) there was a marked decrease in ventilation (80% reduction in ventilatory index and nostril flow), followed by a later 3-fold increase, by which time plasma total ammonia concentration had increased 11-fold. Thus, hyperventilation in HEA appeared to be an indirect response to internal ammonia elevation, rather than a direct response to external ammonia. HEA-mediated increases in oxygen consumption also occurred. Responses to NH4HCO3 were greater than those to NH4Cl, reflecting greater increases over time in water pH and P NH3 in the former. Hagfish also exhibited hyperventilation in response to direct injection of isotonic NH4HCO3 or NH4Cl solutions into the caudal sinus. In all cases where hyperventilation occurred, plasma total ammonia and P NH3 levels increased significantly, while blood acid-base status remained unchanged, indicating specific responses to internal ammonia elevation. The sensitivity of breathing to ammonia arose very early in vertebrate evolution.
Collapse
Affiliation(s)
- Junho Eom
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC, Canada V0R 1B0 .,Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - Marina Giacomin
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC, Canada V0R 1B0.,Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - Alexander M Clifford
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC, Canada V0R 1B0.,Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.,Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9
| | - Greg G Goss
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC, Canada V0R 1B0.,Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9
| | - Chris M Wood
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC, Canada V0R 1B0.,Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| |
Collapse
|
4
|
Zimmer AM, Wright PA, Wood CM. Ammonia and urea handling by early life stages of fishes. ACTA ACUST UNITED AC 2018; 220:3843-3855. [PMID: 29093184 DOI: 10.1242/jeb.140210] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nitrogen metabolism in fishes has been a focus of comparative physiologists for nearly a century. In this Review, we focus specifically on early life stages of fishes, which have received considerable attention in more recent work. Nitrogen metabolism and excretion in early life differs fundamentally from that of juvenile and adult fishes because of (1) the presence of a chorion capsule in embryos that imposes a limitation on effective ammonia excretion, (2) an amino acid-based metabolism that generates a substantial ammonia load, and (3) the lack of a functional gill, which is the primary site of nitrogen excretion in juvenile and adult fishes. Recent findings have shed considerable light on the mechanisms by which these constraints are overcome in early life. Perhaps most importantly, the discovery of Rhesus (Rh) glycoproteins as ammonia transporters and their expression in ion-transporting cells on the skin of larval fishes has transformed our understanding of ammonia excretion by fishes in general. The emergence of larval zebrafish as a model species, together with genetic knockdown techniques, has similarly advanced our understanding of ammonia and urea metabolism and excretion by larval fishes. It has also now been demonstrated that ammonia excretion is one of the primary functions of the developing gill in rainbow trout larvae, leading to new hypotheses regarding the physiological demands driving gill development in larval fishes. Here, we highlight and discuss the dramatic changes in nitrogen handling that occur over early life development in fishes.
Collapse
Affiliation(s)
- Alex M Zimmer
- Department of Biology, University of Ottawa, Ottawa, ON, Canada K1N 6N57
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.,Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1
| |
Collapse
|
5
|
Wilkie MP, Stecyk JAW, Couturier CS, Sidhu S, Sandvik GK, Nilsson GE. Reversible brain swelling in crucian carp (Carassius carassius) and goldfish (Carassius auratus) in response to high external ammonia and anoxia. Comp Biochem Physiol A Mol Integr Physiol 2015; 184:65-75. [PMID: 25582543 DOI: 10.1016/j.cbpa.2014.12.038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 12/30/2014] [Accepted: 12/31/2014] [Indexed: 01/15/2023]
Abstract
Increased internal ammonia (hyperammonemia) and ischemic/anoxic insults are known to result in a cascade of deleterious events that can culminate in potentially fatal brain swelling in mammals. It is less clear, however, if the brains of fishes respond to ammonia in a similar manner. The present study demonstrated that the crucian carp (Carassius carassius) was not only able to endure high environmental ammonia exposure (HEA; 2 to 22 mmol L(-1)) but that they experienced 30% increases in brain water content at the highest ammonia concentrations. This swelling was accompanied by 4-fold increases in plasma total ammonia (TAmm) concentration, but both plasma TAmm and brain water content were restored to pre-exposure levels following depuration in ammonia-free water. The closely related, ammonia-tolerant goldfish (Carassius auratus) responded similarly to HEA (up to 3.6 mmol L(-1)), which was accompanied by 4-fold increases in brain glutamine. Subsequent administration of the glutamine synthetase inhibitor, methionine sulfoximine (MSO), reduced brain glutamine accumulation by 80% during HEA. However, MSO failed to prevent ammonia-induced increases in brain water content suggesting that glutamine may not be directly involved in initiating ammonia-induced brain swelling in fishes. Although the mechanisms of brain swelling are likely different, exposure to anoxia for 96 h caused similar, but lesser (10%) increases in brain water content in crucian carp. We conclude that brain swelling in some fishes may be a common response to increased internal ammonia or lower oxygen but further research is needed to deduce the underlying mechanisms behind such responses.
Collapse
Affiliation(s)
- Michael P Wilkie
- Department of Biology and Institute for Water Science, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5, Canada; Department of Biosciences, University of Oslo, Oslo, Norway.
| | - Jonathan A W Stecyk
- Department of Biosciences, University of Oslo, Oslo, Norway; Department of Biological Sciences, University of Alaska Anchorage, Anchorage, USA
| | | | - Sanya Sidhu
- Department of Biology and Institute for Water Science, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5, Canada
| | - Guro K Sandvik
- Department of Biosciences, University of Oslo, Oslo, Norway
| | | |
Collapse
|
6
|
Clifford AM, Goss GG, Wilkie MP. Adaptations of a deep sea scavenger: high ammonia tolerance and active NH₄⁺ excretion by the Pacific hagfish (Eptatretus stoutii). Comp Biochem Physiol A Mol Integr Physiol 2014; 182:64-74. [PMID: 25499242 DOI: 10.1016/j.cbpa.2014.12.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 12/19/2022]
Abstract
The Pacific hagfish (Eptatretus stoutii) has an exceptional ability to both withstand and recover from exposure to high external ammonia (HEA). This tolerance is likely due to the feeding behavior of this scavenger, which feeds on intermittent food falls of carrion (e.g. fish, large marine mammals) during which time it may be exposed to high concentrations of total ammonia (T(Amm)=NH3+NH4(+)) while burrowed inside the decomposing carcass. Here we exposed hagfish to 20 mmol L(-1) T(Amm) for periods of up to 48 h and then let animals recover in ammonia-free seawater. During the 48 h HEA exposure period, plasma T(Amm) increased 100-fold to over 5000 μmol L(-1) while ammonia excretion (J(amm)) was transiently inhibited. This increase in plasma T(Amm) resulted from NH3 influx down massive inwardly directed ΔP(NH3) gradients, which also led to a short-lived metabolic alkalosis. Plasma [T(Amm)] stabilized after 24-48 h, possibly through a reduction in NH3 permeability across the body surface, which lowered NH3 influx. Ammonia balance was subsequently maintained through the re-establishment of J(amm) against an inwardly directed ΔP(NH3). Calculations of the Nernst potential for ammonia strongly indicated that J(amm) was also taking place against a large inwardly directed NH4(+) electrochemical gradient. Recovery from HEA in ammonia-free water was characterized by a large ammonia washout, and the restoration of plasma TAmm concentrations to near control concentrations. Ammonia clearance was also accompanied by a residual metabolic acidosis, which likely offset the ammonia-induced metabolic alkalosis seen in the early stages of HEA exposure. We conclude that restoration of J(amm) by the Pacific hagfish during ammonia exposure likely involves secondary active transport of NH4(+), possibly mediated by Na(+)/NH4(+) (H(+)) exchange.
Collapse
Affiliation(s)
- Alexander M Clifford
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia, V0R 1B0, Canada.
| | - Greg G Goss
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia, V0R 1B0, Canada
| | - Michael P Wilkie
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, V0R 1B0, Canada; Biology Department, Wilfrid Laurier University, Waterloo, Ontario, N2L 3C5, Canada
| |
Collapse
|
7
|
Bucking C, Lemoine CMR, Walsh PJ. Waste nitrogen metabolism and excretion in zebrafish embryos: effects of light, ammonia, and nicotinamide. ACTA ACUST UNITED AC 2013; 319:391-403. [PMID: 23754660 DOI: 10.1002/jez.1802] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 01/28/2013] [Accepted: 04/01/2013] [Indexed: 11/08/2022]
Abstract
Bony fish primarily excrete ammonia as adults however the persistence of urea cycle genes may reflect a beneficial role for urea production during embryonic stages in protecting the embryo from toxic effects of ammonia produced from a highly nitrogenous yolk. This study aimed to examine the dynamic scope for changes in rates of urea synthesis and excretion in one such species (zebrafish, Danio rerio) by manipulating the intrinsic developmental rate (by alteration of light:dark cycles), as well as by direct chemical manipulation via ammonia injection (to potentially activate urea production) and nicotinamide exposure (to potentially inhibit urea production). Continuous dark exposure delayed development in embryos as evidenced by delayed appearance of hallmark anatomical features (heartbeat, eye pigmentation, body pigmentation, lateral line, fin buds) at 30 and 48 hr post-fertilization, as well by a lower hatching rate compared to embryos reared in continuous light. Both ammonia and urea excretion were similarly effected and were generally higher in embryos continuously exposed to light. Ammonia injection resulted in significant increases (up to fourfold) of urea N excretion and no changes to ammonia excretion rates along with modest increases in yolk ammonia content during 2-6 hr post-injection. Nicotinamide (an inhibitor of urea synthesis in mammals) reduced the ammonia-induced increase in urea excretion and led to retention of ammonia in the yolk and body of the embryo. Our results indicate that there is a relatively rapid and large scope for increases in urea production/excretion rates in developing embryos. Potential mechanisms for these increases are discussed.
Collapse
Affiliation(s)
- Carol Bucking
- Department of Biology, University of Ottawa, Ottawa, ON, Canada.
| | | | | |
Collapse
|
8
|
Wright PA, Wood CM. Seven things fish know about ammonia and we don't. Respir Physiol Neurobiol 2012; 184:231-40. [PMID: 22910326 DOI: 10.1016/j.resp.2012.07.003] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Revised: 07/03/2012] [Accepted: 07/04/2012] [Indexed: 01/01/2023]
Abstract
In this review we pose the following seven questions related to ammonia and fish that represent gaps in our knowledge. 1. How is ammonia excretion linked to sodium uptake in freshwater fish? 2. How much does branchial ammonia excretion in seawater teleosts depend on Rhesus (Rh) glycoprotein-mediated NH(3) diffusion? 3. How do fish maintain ammonia excretion rates if branchial surface area is reduced or compromised? 4. Why does high environmental ammonia change the transepithelial potential across the gills? 5. Does high environmental ammonia increase gill surface area in ammonia tolerant fish but decrease gill surface area in ammonia intolerant fish? 6. How does ammonia contribute to ventilatory control? 7. What do Rh proteins do when they are not transporting ammonia? Mini reviews on each topic, which are able to present only partial answers to each question at present, are followed by further questions and/or suggestions for research approaches targeted to uncover answers.
Collapse
Affiliation(s)
- Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | | |
Collapse
|
9
|
Wilkie MP, Pamenter ME, Duquette S, Dhiyebi H, Sangha N, Skelton G, Smith MD, Buck LT. The relationship between NMDA receptor function and the high ammonia tolerance of anoxia-tolerant goldfish. ACTA ACUST UNITED AC 2012; 214:4107-20. [PMID: 22116753 DOI: 10.1242/jeb.057513] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Acute ammonia toxicity in vertebrates is thought to be characterized by a cascade of deleterious events resembling those associated with anoxic/ischemic injury in the central nervous system. A key event is the over-stimulation of neuronal N-methyl-D-aspartate (NMDA) receptors, which leads to excitotoxic cell death. The similarity between the responses to acute ammonia toxicity and anoxia suggests that anoxia-tolerant animals such as the goldfish (Carassius auratus Linnaeus) may also be ammonia tolerant. To test this hypothesis, the responses of goldfish were compared with those of the anoxia-sensitive rainbow trout (Oncorhynchus mykiss Walbaum) during exposure to high external ammonia (HEA). Acute toxicity tests revealed that goldfish are ammonia tolerant, with 96 h median lethal concentration (LC(50)) values of 199 μmol l(-1) and 4132 μmol l(-1) for NH(3) and total ammonia ([T(Amm)]=[NH(3)]+[NH(4)(+)]), respectively. These values were ~5-6 times greater than corresponding NH(3) and T(Amm) LC(50) values measured in rainbow trout. Further, the goldfish readily coped with chronic exposure to NH(4)Cl (3-5 mmol l(-1)) for 5 days, despite 6-fold increases in plasma [T] to ~1300 μmol l(-1) and 3-fold increases in brain [T(Amm)] to 6700 μmol l(-1). Muscle [T(Amm)] increased by almost 8-fold from ~900 μmol kg(-1) wet mass (WM) to greater than 7000 μmol kg(-1) WM by 48 h, and stabilized. Although urea excretion rates (J(Urea)) increased by 2-3-fold during HEA, the increases were insufficient to offset the inhibition of ammonia excretion that occurred, and increases in urea were not observed in the brain or muscle. There was a marked increase in brain glutamine concentration at HEA, from ~3000 μmol kg(-1) WM to 15,000 μmol kg(-1) WM after 48 h, which is consistent with the hypothesis that glutamine production is associated with ammonia detoxification. Injection of the NMDA receptor antagonists MK801 (0.5-8 mg kg(-1)) or ethanol (1-8 mg kg(-1)) increased trout survival time by 1.5-2.0-fold during exposure to 2 mmol l(-1) ammonia, suggesting that excitotoxic cell death contributes to ammonia toxicity in this species. In contrast, similar doses of MK801 or ethanol had no effect on ammonia-challenged (8-9.5 mmol l(-1) T(Amm)) goldfish survival times, suggesting that greater resistance to excitotoxic cell death contributes to the high ammonia-tolerance of the goldfish. Whole-cell recordings measured in isolated brain slices of goldfish telencephalon during in vitro exposure to 5 mmol l(-1) or 10 mmol l(-1) T(Amm) reversibly potentiated NMDA receptor currents. This observation suggested that goldfish neurons may not be completely resistant to ammonia-induced excitotoxicity. Subsequent western blot and densitometric analyses revealed that NMDA receptor NR1 subunit abundance was 40-60% lower in goldfish exposed to 3-5 mmol l(-1) T(Amm) for 5 days, which was followed by a restoration of NR1 subunit abundance after 3 days recovery in ammonia-free water. We conclude that the goldfish brain may be protected from excitotoxicity by downregulating the abundance of functional NMDA receptors during periods when it experiences increased internal ammonia.
Collapse
Affiliation(s)
- Michael P Wilkie
- Department of Biology, Wilfrid Laurier University, Waterloo, ON, Canada.
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Weihrauch D, Wilkie MP, Walsh PJ. Ammonia and urea transporters in gills of fish and aquatic crustaceans. J Exp Biol 2009; 212:1716-30. [PMID: 19448081 DOI: 10.1242/jeb.024851] [Citation(s) in RCA: 184] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The diversity of mechanisms of ammonia and urea excretion by the gills and other epithelia of aquatic organisms, especially fish and crustaceans, has been studied for decades. Although the decades-old dogma of ;aquatic species excrete ammonia' still explains nitrogenous waste excretion for many species, it is clear that there are many mechanistic variations on this theme. Even within species that are ammonoteles, the process is not purely ;passive', often relying on the energizing effects of proton and sodium-potassium ATPases. Within the ammonoteles, Rh (Rhesus) proteins are beginning to emerge as vital ammonia conduits. Many fishes are also known to be capable of substantial synthesis and excretion of urea as a nitrogenous waste. In such species, members of the UT family of urea transporters have been identified as important players in urea transport across the gills. This review attempts to draw together recent information to update the mechanisms of ammonia and urea transport by the gills of aquatic species. Furthermore, we point out several potentially fruitful avenues for further research.
Collapse
Affiliation(s)
- Dirk Weihrauch
- Department of Biological Sciences, University of Manitoba, 190 Dysart Road, Winnipeg, MB, R3T 2N2 Canada
| | | | | |
Collapse
|
11
|
Wicks BJ, Joensen R, Tang Q, Randall DJ. Swimming and ammonia toxicity in salmonids: the effect of sub lethal ammonia exposure on the swimming performance of coho salmon and the acute toxicity of ammonia in swimming and resting rainbow trout. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2002; 59:55-69. [PMID: 12088633 DOI: 10.1016/s0166-445x(01)00236-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This study tested the hypothesis that swimming exacerbates ammonia toxicity in fish. Both sub-lethal and acute toxicity testing was conducted in a swim tunnel on swimming and resting coho salmon and rainbow trout, respectively. The sub lethal tests on coho salmon also considered the compartmentalization of ammonia within the fish. Coho salmon showed a significant linear decrease in U(crit) both with increasing water ammonia (0, 0.02, 0.04 and 0.08 mg per l NH3) and increasing plasma ammonia. Data collected included plasma pH and ammonia, muscle pH and ammonia and muscle membrane potential. Based on results found in these experiments it was concluded that the reduction in swimming performance was due to both metabolic challenges as well as depolarization of white muscle. Acute toxicity testing on swimming and resting rainbow trout revealed that swimming at (60% U(crit) or approximately 2.2 body lengths/s) decreased the LC50 level from 207+/-21.99 mg N per l in resting fish to 32.38+/-10.81. The LC50 for resting fish was significantly higher than that for swimming fish. The acute value set forth by the US EPA at the same pH is 36.1 mg N per l and may not protect swimming fish. In addition the effect of water hardness on ammonia toxicity was considered. It was found that increased water calcium ameliorates ammonia toxicity in fish living in high pH water.
Collapse
Affiliation(s)
- B J Wicks
- Department of Zoology, University of British Columbia, 6270 University Blvd., BC, Vancouver, Canada.
| | | | | | | |
Collapse
|
12
|
Marcaggi P, Coles JA. Ammonium in nervous tissue: transport across cell membranes, fluxes from neurons to glial cells, and role in signalling. Prog Neurobiol 2001; 64:157-83. [PMID: 11240211 DOI: 10.1016/s0301-0082(00)00043-5] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Most, but not all, animal cell membranes are permeable to NH3, the neutral, minority form of ammonium which is in equilibrium with the charged majority form NH4+. NH4+ crosses many cell membranes via ion channels or on membrane transporters, and cultured mammalian astrocytes and glial cells of bee retina take up NH4+ avidly, in the latter case on a Cl(-)-cotransporter selective for NH4+ over K+. In bee retina, a flux of ammonium from neurons to glial cells is an essential component of energy metabolism, which involves a flux of alanine from glial cells to neurons. In mammalian brain, both glutamate and ammonium are taken up preferentially by astrocytes and form glutamine. Glutamine is transferred to neurons where it is deamidated to re-form glutamate; the maintenance of this cycle appears to require a substantial flux of ammonium from neurons to astrocytes. In addition to maintaining the glial cell content of fixed N (a "bookkeeping" function), ammonium is expected to participate in the regulation of glial cell metabolism (a signalling function): it will increase conversion of glutamate to glutamine, and, by activating phosphofructokinase and inhibiting the alpha-ketoglutarate dehydrogenase complex, it will tend to increase the formation of lactate.
Collapse
Affiliation(s)
- P Marcaggi
- INSERM U394, Institut François Magendie, rue Camille Saint-Saëns, F-33077 Bordeaux Cedex, France
| | | |
Collapse
|
13
|
Influence of feeding, exercise, and temperature on nitrogen metabolism and excretion. FISH PHYSIOLOGY 2001. [DOI: 10.1016/s1546-5098(01)20007-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
|
14
|
Wilkie MP, Wang Y, Walsh PJ, Youson JH. Nitrogenous waste excretion by the larvae of a phylogenetically ancient vertebrate: the sea lamprey (Petromyzon marinus). CAN J ZOOL 1999. [DOI: 10.1139/z99-038] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Larval sea lampreys (Petromyzon marinus) (ammocoetes) excreted significant quantities of urea, which composed 15-20% of the total nitrogenous waste excreted. Compared with teleosts of similar size, ammonia and urea excretion rates (JAmm and JUrea, respectively) in ammocoetes were relatively low, reflecting the low metabolic rate of these burrow-dwelling suspension feeders. Analyses of liver enzymes indicated that ammocoetes had all the enzymes necessary to produce urea via uricolysis, but not those of the ornithine-urea cycle (OUC). Further, exposure to 2 mmol·L-1 total ammonia for 5 d was accompanied by a 3-fold elevation of JUrea, but did not lead to greater OUC activity. Internal ammonia levels increased markedly, however, exceeding 2000 µmol·L-1 in plasma and 5000 µmol·L-1 in muscle after the 5-d exposure period. This high resistance to internal ammonia accumulation was related to the very high glutamine synthetase activities measured in ammocoete brains. The excretion and production of urea by ammocoetes demonstrates for the first time that agnathans are capable of producing physiologically relevant amounts of urea. Given the ancient origins and conserved evolution of lampreys, these observations also suggest that at least some of the early jawless vertebrates were able to produce and excrete urea.
Collapse
|
15
|
Wang Y, Henry RP, Wright PM, Heigenhauser GJ, Wood CM. Respiratory and metabolic functions of carbonic anhydrase in exercised white muscle of trout. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:R1766-79. [PMID: 9843866 DOI: 10.1152/ajpregu.1998.275.6.r1766] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Electrical stimulation of a trout saline-perfused trunk preparation resulted in metabolic and respiratory responses comparable to those occurring after exhaustive exercise in vivo. Recovery of intracellular acid-base status and glycogen resynthesis were faster than in vivo. Intracellular carbonic anhydrase (ICF CA) blockade elevated intracellular PCO2 relative to untreated postexercise controls, whereas extracellular CA (ECF CA) blockade did not, in contrast to previous work with muscle at rest. ECF CA blockade had only a transient effect on postexercise CO2 and ammonia efflux. The relatively small pool of membrane-associated CA appears to be overwhelmed by exercise-induced CO2 production in muscle. Transmembrane ammonia efflux appears to shift from diffusion primarily as NH3 at rest, which is facilitated by ECF CA, to movement predominantly as NH+4 after exercise, which is independent of CA. The postponed recovery of intracellular pH caused by either or both ECF and ICF CA inhibition was consistent with reduced metabolic acid and lactate excretion from muscle. Creatine phosphate resynthesis was delayed by CA inhibition, whereas ATP replenishment was not affected. Delayed glycogen recovery indicates that HCO-3-dependent pathway(s) may be involved in glyconeogenesis.
Collapse
Affiliation(s)
- Y Wang
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida 33149, USA
| | | | | | | | | |
Collapse
|
16
|
|
17
|
|
18
|
|
19
|
WALSH PATRICKJ, HENRY RAYMONDP. Carbon dioxide and ammonia metabolism and exchange. PHYLOGENETIC AND BIOCHEMICAL PERSPECTIVES 1991. [DOI: 10.1016/b978-0-444-89124-2.50012-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
|
20
|
Milligan CL, McDonald DG, Prior T. Branchial Acid and Ammonia Fluxes in Response to Alkalosis and Acidosis in Two Marine Teleosts: Coho Salmon (Oncorhynchus kisutch) and Starry Flounder (Platichthys stellatus). ACTA ACUST UNITED AC 1991. [DOI: 10.1086/physzool.64.1.30158518] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
21
|
|
22
|
Wood CM, Perry SF, Wright PA, Bergman HL, Randall DJ. Ammonia and urea dynamics in the Lake Magadi tilapia, a ureotelic teleost fish adapted to an extremely alkaline environment. RESPIRATION PHYSIOLOGY 1989; 77:1-20. [PMID: 2799103 DOI: 10.1016/0034-5687(89)90025-x] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The tilapia Oreochromis alcalicus grahami, which thrives under harshly alkaline conditions in Lake Magadi, Kenya, was studied in its natural environment (pH = 10, total CO2 = 180 mmol/L, osmolality = 525 mOsm/kg, 30-36.5 degrees C). At rest, this species excretes all nitrogenous waste as urea. This is the first known instance of complete ureotelism in an entirely aquatic teleost fish. Very small 'apparent' ammonia excretion (less than 5% of overall N excretion) was attributable to faecal/bacterial production. Ammonia excretion could not be induced by feeding, reduced temperature, or exposure to pH 7. Exhaustive exercise induced only a small efflux of ammonia. Urea output was inhibited completely by pH 7 water and partly by exhaustive exercise, and greatly stimulated by exposure to 500 mumol/L NH3 (at pH 10). A related species, nominally Oreochromis nilotica, which lives in freshwater at circumneutral pH in the same geographic region, excretes 85% ammonia-N and 15% urea-N at pH 7 in the standard teleost fashion. Urea-N efflux increased to 33% upon transfer of O. nilotica to pH 10 in freshwater. Urea output in this species was only marginally stimulated by exposure to 500 mumol/L NH3 (at pH 7). Plasma and white muscle urea levels were 4- to 5-fold higher in O. a. grahami than in O. nilotica, and plasma levels increased between caudal and cardiac sampling sites, indicating hepatic ureagenesis. Blood pH and PNH3 levels, when corrected for sampling artifact, were unusually high in O. a. grahami. We hypothesize that complete ureotelism in O. a. grahami is an evolutionary response to the problems of excreting ammonia into highly buffered water at pH 10 and/or acid-base balance in this extreme environment.
Collapse
Affiliation(s)
- C M Wood
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | | | | | | | | |
Collapse
|