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Williamson G, Bizior A, Harris T, Pritchard L, Hoskisson P, Javelle A. Biological ammonium transporters from the Amt/Mep/Rh superfamily: mechanism, energetics, and technical limitations. Biosci Rep 2024; 44:BSR20211209. [PMID: 38131184 PMCID: PMC10794816 DOI: 10.1042/bsr20211209] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 12/12/2023] [Accepted: 12/21/2023] [Indexed: 12/23/2023] Open
Abstract
The exchange of ammonium across cellular membranes is a fundamental process in all domains of life and is facilitated by the ubiquitous Amt/Mep/Rh transporter superfamily. Remarkably, despite a high structural conservation in all domains of life, these proteins have gained various biological functions during evolution. It is tempting to hypothesise that the physiological functions gained by these proteins may be explained at least in part by differences in the energetics of their translocation mechanisms. Therefore, in this review, we will explore our current knowledge of energetics of the Amt/Mep/Rh family, discuss variations in observations between different organisms, and highlight some technical drawbacks which have hampered effects at mechanistic characterisation. Through the review, we aim to provide a comprehensive overview of current understanding of the mechanism of transport of this unique and extraordinary Amt/Mep/Rh superfamily of ammonium transporters.
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Affiliation(s)
- Gordon Williamson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K
| | - Adriana Bizior
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K
| | - Thomas Harris
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K
| | - Leighton Pritchard
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K
| | - Paul A. Hoskisson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K
| | - Arnaud Javelle
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K
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2
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Bizior A, Williamson G, Harris T, Hoskisson PA, Javelle A. Prokaryotic ammonium transporters: what has three decades of research revealed? MICROBIOLOGY (READING, ENGLAND) 2023; 169:001360. [PMID: 37450375 PMCID: PMC10433425 DOI: 10.1099/mic.0.001360] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 06/24/2023] [Indexed: 07/18/2023]
Abstract
The exchange of ammonium across cellular membranes is a fundamental process in all domains of life. In plants, bacteria and fungi, ammonium represents a vital source of nitrogen, which is scavenged from the external environment. In contrast, in animal cells ammonium is a cytotoxic metabolic waste product and must be excreted to prevent cell death. Transport of ammonium is facilitated by the ubiquitous Amt/Mep/Rh transporter superfamily. In addition to their function as transporters, Amt/Mep/Rh proteins play roles in a diverse array of biological processes and human physiopathology. Despite this clear physiological importance and medical relevance, the molecular mechanism of Amt/Mep/Rh proteins has remained elusive. Crystal structures of bacterial Amt/Rh proteins suggest electroneutral transport, whilst functional evidence supports an electrogenic mechanism. Here, focusing on bacterial members of the family, we summarize the structure of Amt/Rh proteins and what three decades of research tells us concerning the general mechanisms of ammonium translocation, in particular the possibility that the transport mechanism might differ in various members of the Amt/Mep/Rh superfamily.
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Affiliation(s)
- Adriana Bizior
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK
| | - Gordon Williamson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK
| | - Thomas Harris
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK
| | - Paul A. Hoskisson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK
| | - Arnaud Javelle
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK
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3
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Stainer S, Reisetbauer S, Ahiable JEA, Ebner L, Zhu R, Reindl D, Körmöczi GF, Ebner A. Single molecule distribution of RhD binding epitopes on ultraflat erythrocyte ghosts. NANOSCALE 2020; 12:22097-22106. [PMID: 33118583 DOI: 10.1039/d0nr04393a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The Rh blood group system plays a key role in transfusion and organ transplant medicine. The complex transmembrane Rh polypeptides RhD and RhCE carry numerous antigens, including the extremely immunogenic D antigen. The Rh polypeptides form multimolecular Rh complexes with certain transmembrane and skeletal proteins, with so far only incompletely understood physiological functions. Determination of the energy landscape of individual Rh binding epitopes towards their specific interaction partners as well as their localization across the red blood cell (RBC) membrane requires single molecule approaches including large area high resolution recognition imaging. Atomic force microscopy based molecular recognition force spectroscopy in combination with single molecule recognition imaging fulfills these requirements. For unbiased single molecule results, nano-mechanical influences due to cell elasticity have to be eliminated. This is realized by generation of ultra flat erythrocyte ghosts on a solid support. We developed a protocol for the preparation of complete ultraflat erythrocyte ghosts and determined the molecular binding behaviour of different anti-D antibodies towards their binding epitopes on RhD positive and negative erythrocytes. Performing optimized topography and recognition imaging at 16 Mpixel resolution allowed localisation of individual RhD molecules at the single molecule level across an entire RBC. A map of Rh antigens across integer ultraflat RBC ghosts was generated with nanometer resolution. Here we show a homogeneous distribution on rim and dimple regions with comparable receptor densities. Furthermore, differences in the energy landscape between specific monoclonal antibodies were determined at the single molecule level.
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Affiliation(s)
- Sarah Stainer
- Molecular Biosensing group, Institute of Biophysics, Johannes Kepler University Linz, Austria.
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Allen WJ, Collinson I. A molecular dual carriageway. eLife 2020; 9:61148. [PMID: 32840481 PMCID: PMC7447420 DOI: 10.7554/elife.61148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 08/17/2020] [Indexed: 11/29/2022] Open
Abstract
In order to enter a cell, an ammonium ion must first dissociate to form an ammonia molecule and a hydrogen ion (a proton), which then pass through the cell membrane separately and recombine inside.
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Affiliation(s)
- William J Allen
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
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5
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Williamson G, Tamburrino G, Bizior A, Boeckstaens M, Dias Mirandela G, Bage MG, Pisliakov A, Ives CM, Terras E, Hoskisson PA, Marini AM, Zachariae U, Javelle A. A two-lane mechanism for selective biological ammonium transport. eLife 2020; 9:57183. [PMID: 32662768 PMCID: PMC7447429 DOI: 10.7554/elife.57183] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 07/13/2020] [Indexed: 11/13/2022] Open
Abstract
The transport of charged molecules across biological membranes faces the dual problem of accommodating charges in a highly hydrophobic environment while maintaining selective substrate translocation. This has been the subject of a particular controversy for the exchange of ammonium across cellular membranes, an essential process in all domains of life. Ammonium transport is mediated by the ubiquitous Amt/Mep/Rh transporters that includes the human Rhesus factors. Here, using a combination of electrophysiology, yeast functional complementation and extended molecular dynamics simulations, we reveal a unique two-lane pathway for electrogenic NH4+ transport in two archetypal members of the family, the transporters AmtB from Escherichia coli and Rh50 from Nitrosomonas europaea. The pathway underpins a mechanism by which charged H+ and neutral NH3 are carried separately across the membrane after NH4+ deprotonation. This mechanism defines a new principle of achieving transport selectivity against competing ions in a biological transport process.
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Affiliation(s)
- Gordon Williamson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Giulia Tamburrino
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Adriana Bizior
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Mélanie Boeckstaens
- Biology of Membrane Transport Laboratory, Department of Molecular Biology, Université Libre de Bruxelles, Gosselies, Belgium
| | - Gaëtan Dias Mirandela
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Marcus G Bage
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Andrei Pisliakov
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Callum M Ives
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Eilidh Terras
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Paul A Hoskisson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Anna Maria Marini
- Biology of Membrane Transport Laboratory, Department of Molecular Biology, Université Libre de Bruxelles, Gosselies, Belgium
| | - Ulrich Zachariae
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Arnaud Javelle
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
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De Boeck G, Wood CM, Brix KV, Sinha AK, Matey V, Johannsson OE, Bianchini A, Bianchini LF, Maina JN, Kavembe GD, Papah MB, Kisipan ML, Ojoo RO. Fasting in the ureotelic Lake Magadi tilapia, Alcolapia grahami, does not reduce its high metabolic demand, increasing its vulnerability to siltation events. CONSERVATION PHYSIOLOGY 2019; 7:coz060. [PMID: 31687141 PMCID: PMC6822538 DOI: 10.1093/conphys/coz060] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 07/16/2019] [Accepted: 07/25/2019] [Indexed: 06/10/2023]
Abstract
Lake Magadi, Kenya, is one of the most extreme aquatic environments on Earth (pH~10, anoxic to hyperoxic, high temperatures). Recently, increased water demand and siltation have threatened the viable hot springs near the margins of the lake where Alcolapia grahami, the only fish surviving in the lake, live. These Lake Magadi tilapia largely depend on nitrogen-rich cyanobacteria for food and are 100% ureotelic. Their exceptionally high aerobic metabolic rate, together with their emaciated appearance, suggests that they are energy-limited. Therefore, we hypothesized that during food deprivation, Magadi tilapia would economize their energy expenditure and reduce metabolic rate, aerobic performance and urea-N excretion. Surprisingly, during a 5-day fasting period, routine metabolic rates increased and swimming performance (critical swimming speed) was not affected. Urea-N excretion remained stable despite the lack of their N-rich food source. Their nitrogen use switched to endogenous sources as liver and muscle protein levels decreased after a 5-day fast, indicating proteolysis. Additionally, fish relied on carbohydrates with lowered muscle glycogen levels, but there were no signs indicating use of lipid stores. Gene expression of gill and gut urea transporters were transiently reduced as were gill rhesus glycoprotein Rhbg and Rhcg-2. The reduction in gill glutamine synthetase expression concomitant with the reduction in Rh glycoprotein gene expression indicates reduced nitrogen/ammonia metabolism, most likely decreased protein synthesis. Additionally, fish showed reduced plasma total CO2, osmolality and Na+ (but not Cl-) levels, possibly related to reduced drinking rates and metabolic acidosis. Our work shows that Lake Magadi tilapia have the capacity to survive short periods of starvation which could occur when siltation linked to flash floods covers their main food source, but their seemingly hardwired high metabolic rates would compromise long-term survival.
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Affiliation(s)
- Gudrun De Boeck
- SPHERE, Department of Biology, Groenenborgerlaan 171, University of Antwerp, Antwerp B-2020, Belgium
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Riverside Drive, Chiromo Campus, PO Box 30197-00100, Nairobi 30197, Kenya
| | - Chris M Wood
- Department of Biology, McMaster University, 1280 Main St W, Hamilton, ON L8S 4K1, Canada
- Department of Zoology, University of British Columbia, 6270 Univ Blvd, Vancouver, BC V6T 1Z4, Canada
- Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Riverside Drive, Chiromo Campus, PO Box 30197-00100, Nairobi 30197, Kenya
| | - Kevin V Brix
- Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA
- EcoTox, 3211 19th Terrace, Miami, FL 33145, USA
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Riverside Drive, Chiromo Campus, PO Box 30197-00100, Nairobi 30197, Kenya
| | - Amit K Sinha
- SPHERE, Department of Biology, Groenenborgerlaan 171, University of Antwerp, Antwerp B-2020, Belgium
- Department of Aquaculture and Fisheries, University of Arkansas, 1200 North Univ Dr, Pine Bluff, AR 71601, USA
| | - Victoria Matey
- Department of Biology, San Diego State University, 5500 Campanile Dr., San Diego, CA 92182, USA
| | - Ora E Johannsson
- Department of Zoology, University of British Columbia, 6270 Univ Blvd, Vancouver, BC V6T 1Z4, Canada
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Riverside Drive, Chiromo Campus, PO Box 30197-00100, Nairobi 30197, Kenya
| | - Adalto Bianchini
- Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, Ave Italia Km 8, Rio Grande, RS 96203-900, Brazil
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Riverside Drive, Chiromo Campus, PO Box 30197-00100, Nairobi 30197, Kenya
| | - Lucas F Bianchini
- Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, Ave Italia Km 8, Rio Grande, RS 96203-900, Brazil
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Riverside Drive, Chiromo Campus, PO Box 30197-00100, Nairobi 30197, Kenya
| | - John N Maina
- Department of Zoology, University of Johannesburg, PO Box 524 Auckland Park, Johannesburg 2006, South Africa
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Riverside Drive, Chiromo Campus, PO Box 30197-00100, Nairobi 30197, Kenya
| | - Geraldine D Kavembe
- School of Dryland Agriculture Science and Technology, South Eastern Kenya University, PO Box 170, Kitui 90200, Kenya
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Riverside Drive, Chiromo Campus, PO Box 30197-00100, Nairobi 30197, Kenya
| | - Michael B Papah
- Department of Animal and Food Sciences, University of Delaware, 531 S. College Ave., Newark, DE 19716, USA
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Riverside Drive, Chiromo Campus, PO Box 30197-00100, Nairobi 30197, Kenya
| | - Mosiany L Kisipan
- Department of Veterinary Anatomy and Physiology, Egerton University, Njoro Campus PO Box 536, Egerton 20115, Kenya
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Riverside Drive, Chiromo Campus, PO Box 30197-00100, Nairobi 30197, Kenya
| | - Rodi O Ojoo
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Riverside Drive, Chiromo Campus, PO Box 30197-00100, Nairobi 30197, Kenya
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Lecompte M, Cattaert D, Vincent A, Birman S, Chérif-Zahar B. Drosophila ammonium transporter Rh50 is required for integrity of larval muscles and neuromuscular system. J Comp Neurol 2019; 528:81-94. [PMID: 31273786 DOI: 10.1002/cne.24742] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 05/30/2019] [Accepted: 06/21/2019] [Indexed: 12/18/2022]
Abstract
Rhesus glycoproteins (Rh50) have been shown to be ammonia transporters in many species from bacteria to human. They are involved in various physiological processes including acid excretion and pH regulation. Rh50 proteins can also provide a structural link between the cytoskeleton and the plasma membranes that maintain cellular integrity. Although ammonia plays essential roles in the nervous system, in particular at glutamatergic synapses, a potential role for Rh50 proteins at synapses has not yet been investigated. To better understand the function of these proteins in vivo, we studied the unique Rh50 gene of Drosophila melanogaster, which encodes two isoforms, Rh50A and Rh50BC. We found that Drosophila Rh50A is expressed in larval muscles and enriched in the postsynaptic regions of the glutamatergic neuromuscular junctions. Rh50 inactivation by RNA interference selectively in muscle cells caused muscular atrophy in larval stages and pupal lethality. Interestingly, Rh50-deficiency in muscles specifically increased glutamate receptor subunit IIA (GluRIIA) level and the frequency of spontaneous excitatory postsynaptic potentials. Our work therefore highlights a new role for Rh50 proteins in the maintenance of Drosophila muscle architecture and synaptic physiology, which could be conserved in other species.
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Affiliation(s)
- Mathilde Lecompte
- Genes Circuits Rhythmes et Neuropathologies, Plasticité du Cerveau, ESPCI Paris, CNRS, PSL University, Paris, France
| | - Daniel Cattaert
- Institut des Neurosciences Cognitives et Intégratives d'Aquitaine, CNRS, Bordeaux University, Bordeaux, France
| | - Alain Vincent
- Centre de Biologie du Développement, Centre de Biologie Intégrative, CNRS, Toulouse University, UPS, Toulouse, France
| | - Serge Birman
- Genes Circuits Rhythmes et Neuropathologies, Plasticité du Cerveau, ESPCI Paris, CNRS, PSL University, Paris, France
| | - Baya Chérif-Zahar
- Genes Circuits Rhythmes et Neuropathologies, Plasticité du Cerveau, ESPCI Paris, CNRS, PSL University, Paris, France
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Seebacher V, Polterauer S, Reinthaller A, Koelbl H, Achleitner R, Berger A, Concin N. AB0 blood groups and rhesus factor expression as prognostic parameters in patients with epithelial ovarian cancer - a retrospective multi-centre study. BMC Cancer 2018; 18:447. [PMID: 29673336 PMCID: PMC5909228 DOI: 10.1186/s12885-018-4289-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 03/21/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND AB0 blood groups and Rhesus factor expression have been associated with carcinogenesis, response to treatment and tumor progression in several malignancies. The aim of the present study was to test the hypothesis that AB0 blood groups and Rhesus factor expression are associated with clinical outcome in patients with epithelial ovarian cancer (EOC). METHODS AB0 blood groups and Rhesus factor expression were evaluated in a retrospective multicenter study including 518 patients with EOC. Their association with patients' survival was assessed using univariate and multivariable analyses. RESULTS Neither AB0 blood groups nor Rhesus factor expression were associated with clinico-pathological parameters, recurrence-free, cancer-specific, or overall survival. In a subgroup of patients with high-grade serous adenocarcinoma, however, blood groups B and AB were associated with a better 5-year cancer-specific survival rate compared to blood groups A and 0 (60.3 ± 8.6% vs. 43.8 ± 3.6%, p = 0.04). Yet, this was not significant in multivariable analysis. CONCLUSIONS AB0 blood groups and Rhesus factor expression are both neither associated with features of biologically aggressive disease nor clinical outcome in patients with EOC. Further investigation of the role of the blood group B antigen on cancer-specific survival in the subgroup of high-grade serous should be considered.
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Affiliation(s)
- Veronika Seebacher
- Department of Gynecology and Gynecologic Oncology, Comprehensive Cancer Center Vienna, Gynecologic Cancer Unit, Medical University of Vienna, Spitalgasse 23, 1090, Vienna, Austria.
| | - Stephan Polterauer
- Department of Gynecology and Gynecologic Oncology, Comprehensive Cancer Center Vienna, Gynecologic Cancer Unit, Medical University of Vienna, Spitalgasse 23, 1090, Vienna, Austria.,Karl Landsteiner Institute for General Gynecology and Experimental Gynecologic Oncology, Franziskanergasse 4a, 3100, St. Pölten, Austria
| | - Alexander Reinthaller
- Department of Gynecology and Gynecologic Oncology, Comprehensive Cancer Center Vienna, Gynecologic Cancer Unit, Medical University of Vienna, Spitalgasse 23, 1090, Vienna, Austria.,Karl Landsteiner Institute for General Gynecology and Experimental Gynecologic Oncology, Franziskanergasse 4a, 3100, St. Pölten, Austria
| | - Heinz Koelbl
- Department of Gynecology and Gynecologic Oncology, Comprehensive Cancer Center Vienna, Gynecologic Cancer Unit, Medical University of Vienna, Spitalgasse 23, 1090, Vienna, Austria
| | - Regina Achleitner
- Department of Gynaecology and Obstetrics, Medical University of Innsbruck, Innrain 52, Christoph-Probst-Platz, 6010, Innsbruck, Austria
| | - Astrid Berger
- Department of Gynaecology and Obstetrics, Medical University of Innsbruck, Innrain 52, Christoph-Probst-Platz, 6010, Innsbruck, Austria
| | - Nicole Concin
- Department of Gynaecology and Obstetrics, Medical University of Innsbruck, Innrain 52, Christoph-Probst-Platz, 6010, Innsbruck, Austria
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9
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Chng YR, Ong JLY, Ching B, Chen XL, Hiong KC, Wong WP, Chew SF, Lam SH, Ip YK. Molecular characterization of three Rhesus glycoproteins from the gills of the African lungfish, Protopterus annectens, and effects of aestivation on their mRNA expression levels and protein abundance. PLoS One 2017; 12:e0185814. [PMID: 29073147 PMCID: PMC5657625 DOI: 10.1371/journal.pone.0185814] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 09/20/2017] [Indexed: 11/19/2022] Open
Abstract
African lungfishes are ammonotelic in water. They can aestivate for long periods on land during drought. During aestivation, the gills are covered with dried mucus and ammonia excretion ceases. In fishes, ammonia excretion through the gills involves Rhesus glycoproteins (RhGP/Rhgp). This study aimed to obtain the complete cDNA coding sequences of rhgp from the gills of Protopterus annectens, and to determine their branchial mRNA and protein expression levels during the induction, maintenance and arousal phases of aestivation. Three isoforms of rhgp (rhag, rhbg and rhcg) were obtained in the gills of P. annectens. Their complete cDNA coding sequences ranged between 1311 and 1398 bp, coding for 436 to 465 amino acids with estimated molecular masses between 46.8 and 50.9 kDa. Dendrogramic analyses indicated that Rhag was grouped closer to fishes, while Rhbg and Rhcg were grouped closer to tetrapods. During the induction phase, the protein abundance of Rhag, but not its transcript level, was down-regulated in the gills, suggesting that there could be a decrease in the release of ammonia from the erythrocytes to the plasma. Furthermore, the branchial transcript levels of rhbg and rhcg decreased significantly, in preparation for the subsequent shutdown of gill functions. During the maintenance phase, the branchial expression levels of rhag/Rhag, rhbg/Rhbg and rhcg/Rhcg decreased significantly, indicating that their transcription and translation were down-regulated. This could be part of an overall mechanism to shut down branchial functions and save metabolic energy used for transcription and translation. It could also be regarded as an adaptive response to stop ammonia excretion. During the arousal phase, it is essential for the lungfish to regain the ability to excrete ammonia. Indeed, the protein abundance of Rhag, Rhbg and Rhcg recovered to the corresponding control levels after 1 day or 3 days of recovery from 6 months of aestivation.
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Affiliation(s)
- You R. Chng
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Jasmine L. Y. Ong
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Biyun Ching
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Xiu L. Chen
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Kum C. Hiong
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Wai P. Wong
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Shit F. Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore
| | - Siew H. Lam
- Department of Biological Sciences, National University of Singapore, Singapore
- NUS Environmental Research Institute, National University of Singapore, Singapore
| | - Yuen K. Ip
- Department of Biological Sciences, National University of Singapore, Singapore
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10
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Adlimoghaddam A, O'Donnell MJ, Kormish J, Banh S, Treberg JR, Merz D, Weihrauch D. Ammonia excretion in Caenorhabditis elegans: Physiological and molecular characterization of the rhr-2 knock-out mutant. Comp Biochem Physiol A Mol Integr Physiol 2016; 195:46-54. [DOI: 10.1016/j.cbpa.2016.02.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 02/04/2016] [Accepted: 02/07/2016] [Indexed: 12/16/2022]
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11
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Caner T, Abdulnour-Nakhoul S, Brown K, Islam MT, Hamm LL, Nakhoul NL. Mechanisms of ammonia and ammonium transport by rhesus-associated glycoproteins. Am J Physiol Cell Physiol 2015; 309:C747-58. [PMID: 26354748 DOI: 10.1152/ajpcell.00085.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 09/02/2015] [Indexed: 01/24/2023]
Abstract
In this study we characterized ammonia and ammonium (NH3/NH4(+)) transport by the rhesus-associated (Rh) glycoproteins RhAG, Rhbg, and Rhcg expressed in Xenopus oocytes. We used ion-selective microelectrodes and two-electrode voltage clamp to measure changes in intracellular pH, surface pH, and whole cell currents induced by NH3/NH4(+) and methyl amine/ammonium (MA/MA(+)). These measurements allowed us to define signal-specific signatures to distinguish NH3 from NH4(+) transport and to determine how transport of NH3 and NH4(+) differs among RhAG, Rhbg, and Rhcg. Our data indicate that expression of Rh glycoproteins in oocytes generally enhanced NH3/NH4(+) transport and that cellular changes induced by transport of MA/MA(+) by Rh proteins were different from those induced by transport of NH3/NH4(+). Our results support the following conclusions: 1) RhAG and Rhbg transport both the ionic NH4(+) and neutral NH3 species; 2) transport of NH4(+) is electrogenic; 3) like Rhbg, RhAG transport of NH4(+) masks NH3 transport; and 4) Rhcg is likely to be a predominantly NH3 transporter, with no evidence of enhanced NH4(+) transport by this transporter. The dual role of Rh proteins as NH3 and NH4(+) transporters is a unique property and may be critical in understanding how transepithelial secretion of NH3/NH4(+) occurs in the renal collecting duct.
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Affiliation(s)
- Tolga Caner
- Section of Nephrology, Department of Medicine, and Department of Physiology, Southeast Louisiana Veterans Health Care System, New Orleans, Louisiana; and Tulane Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, Louisiana
| | - Solange Abdulnour-Nakhoul
- Section of Nephrology, Department of Medicine, and Department of Physiology, Southeast Louisiana Veterans Health Care System, New Orleans, Louisiana; and Tulane Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, Louisiana
| | - Karen Brown
- Section of Nephrology, Department of Medicine, and Department of Physiology, Southeast Louisiana Veterans Health Care System, New Orleans, Louisiana; and Tulane Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, Louisiana
| | - M Toriqul Islam
- Section of Nephrology, Department of Medicine, and Department of Physiology, Southeast Louisiana Veterans Health Care System, New Orleans, Louisiana; and Tulane Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, Louisiana
| | - L Lee Hamm
- Section of Nephrology, Department of Medicine, and Department of Physiology, Southeast Louisiana Veterans Health Care System, New Orleans, Louisiana; and Tulane Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, Louisiana
| | - Nazih L Nakhoul
- Section of Nephrology, Department of Medicine, and Department of Physiology, Southeast Louisiana Veterans Health Care System, New Orleans, Louisiana; and Tulane Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, Louisiana
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12
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Quijada-Rodriguez AR, Treberg JR, Weihrauch D. Mechanism of ammonia excretion in the freshwater leech Nephelopsis obscura: characterization of a primitive Rh protein and effects of high environmental ammonia. Am J Physiol Regul Integr Comp Physiol 2015; 309:R692-705. [PMID: 26180186 DOI: 10.1152/ajpregu.00482.2014] [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: 12/01/2014] [Accepted: 07/14/2015] [Indexed: 12/23/2022]
Abstract
Remarkably little is known about nitrogenous excretion in freshwater invertebrates. In the current study, the nitrogen excretion mechanism in the carnivorous ribbon leech, Nephelopsis obscura, was investigated. Excretion experiments showed that the ribbon leech is ammonotelic, excreting 166.0 ± 8.6 nmol·grams fresh weight (gFW)(-1)·h(-1) ammonia and 14.7 ± 1.9 nmol·gFW(-1)·h(-1) urea. Exposure to high and low pH hampered and enhanced, respectively, ammonia excretion rates, indicating an acid-linked ammonia trapping mechanism across the skin epithelia. Accordingly, compared with body tissues, the skin exhibited elevated mRNA expression levels of a newly identified Rhesus protein and at least in tendency the Na(+)/K(+)-ATPase. Pharmacological experiments and enzyme assays suggested an ammonia excretion mechanism that involves the V-ATPase, Na(+)/K(+)-ATPase, and carbonic anhydrase, but not necessarily a functional microtubule system. Most importantly, functional expression studies of the identified Rh protein cloned from leech skin tissue revealed an ammonia transport capability of this protein when expressed in yeast. The leech Rh-ammonia transporter (NoRhp) is a member of the primitive Rh protein family, which is a sister group to the common ancestor of vertebrate ammonia-transporting Rh proteins. Exposure to high environmental ammonia (HEA) caused a new adjustment of body ammonia, accompanied with a decrease in NoRhp and Na(+)/K(+)-ATPase mRNA levels, but unaltered ammonia excretion rates. To our knowledge, this is only the second comprehensive study regarding the ammonia excretion mechanisms in a freshwater invertebrate, but our results show that basic processes of ammonia excretion appear to also be comparable to those found in freshwater fish, suggesting an early evolution of ionoregulatory mechanisms in freshwater organisms.
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Affiliation(s)
| | - Jason R Treberg
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada; and Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Dirk Weihrauch
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada; and
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13
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Edwards SL, Arnold J, Blair SD, Pray M, Bradley R, Erikson O, Walsh PJ. Ammonia excretion in the Atlantic hagfish (Myxine glutinosa) and responses of an Rhc glycoprotein. Am J Physiol Regul Integr Comp Physiol 2015; 308:R769-78. [DOI: 10.1152/ajpregu.00355.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 02/20/2015] [Indexed: 12/21/2022]
Abstract
Hagfishes, the most ancient of the extant craniates, demonstrate a high tolerance for a number of unfavorable environmental conditions, including elevated ammonia. Proposed mechanisms of ammonia excretion in aquatic organisms include vesicular NH4+ transport and release by exocytosis in marine crabs, and passive NH3 diffusion, active NH4+ transport, and paracellular leakage of NH3 or NH4+ across the gills of fishes. Recently, an emerging paradigm suggests that Rhesus glycoproteins play a vital role in ammonia transport in both aquatic invertebrates and vertebrates. This study has identified an Rh glycoprotein ortholog from the gills of Atlantic hagfish. The hagfish Rhcg shares a 56–60% amino acid identity to other vertebrate Rhcg cDNAs. Sequence information was used to produce an anti-hagfish Rhcg (hRhcg) antibody. We have used hRhcg to localize protein expression to epithelial cells of the gill and the skin. In addition, we have quantified hRhcg expression following exposure to elevated plasma ammonia levels. Animals exposed to a 3 mmol/kg NH4Cl load resulted in significantly elevated plasma ammonia concentrations compared with controls for up to 4 h postinjection. This correlated with net ammonia excretion rates that were also significantly elevated for up to 4 h postinjection. Rhcg mRNA expression in both the gill and skin was significantly elevated by 15 min and 1 h, respectively, and hRhcg protein expression in gills was significantly elevated at 2, 4, and 8 h postinjection. These results demonstrate a potential role for Rhcg in the excretion of ammonia in the Atlantic hagfish.
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Affiliation(s)
- Susan L. Edwards
- Department of Biology, Appalachian State University, Boone, North Carolina
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Justin Arnold
- Department of Biology, Appalachian State University, Boone, North Carolina
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Salvatore D. Blair
- Department of Biology, Appalachian State University, Boone, North Carolina
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Margaret Pray
- Department of Biology, Appalachian State University, Boone, North Carolina
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Rachel Bradley
- Department of Biology, Appalachian State University, Boone, North Carolina
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Olivia Erikson
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Patrick J. Walsh
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
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14
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Engel O, Soave A, Peine S, Kluth LA, Schmid M, Shariat SF, Dahlem R, Fisch M, Rink M. The impact of the AB0 and the Rhesus blood group system on outcomes in bladder cancer patients treated with radical cystectomy. World J Urol 2015; 33:1769-76. [DOI: 10.1007/s00345-015-1531-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 03/05/2015] [Indexed: 11/25/2022] Open
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15
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Musa RH, Muhamad NA, Hassan A, Ayob Y, Yusoff NM. Molecular basis of Rh blood group system in the Malaysian population. Asian J Transfus Sci 2015; 9:48-54. [PMID: 25722573 PMCID: PMC4339932 DOI: 10.4103/0973-6247.150951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Rh molecular studies have been previously mainly conducted in Caucasians and African population. There is a limited data on the molecular basis for Rh genotypes among Asians. AIMS This study aims to characterize the Rh genes and frequency of the various RH genotypes among blood donors in National Blood Centre (NBC), Kuala Lumpur. MATERIALS AND METHODS A total of 1014 blood samples were obtained from blood donors from four different ethnic groups (360 Malays, 434 Chinese, 164 Indians and 56 others). Serological and molecular analysis of all 1014 blood samples were performed. An automated deoxyribonucleic acid sequencing analysis was performed. RESULTS Rh phenotypes and RH genotypes showed heterogeneity and significant association with ethnicities. Discrepancies in allele D, C/c and E/e between phenotypes and genotypes results were observed. Discrepancy results in allele D showed significant association with the ethnic groups of the blood donors in NBC. There were multiple novel mutations (23) and published mutations (5) found in this study. Significant associations between discrepancy results and mutations were found in allele D and C/c. CONCLUSION Performing RH molecular analysis in Malaysian population provided the basic database for the distribution of Rh genotypes of donors from major ethnic groups in Malaysia.
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Affiliation(s)
- Rozi Hanisa Musa
- Regenerative Medicine Cluster, Advanced Medical and Dental Institute, Universiti Sains Malaysia, Bertam, Pulau Penang, Malaysia ; Immunohematology Division, National Blood Center, Institute for Medical Research, Kuala Lumpur, Malaysia
| | - Nor Asiah Muhamad
- Medical Research Resource Centre, Institute for Medical Research, Kuala Lumpur, Malaysia
| | - Afifah Hassan
- Immunohematology Division, National Blood Center, Institute for Medical Research, Kuala Lumpur, Malaysia
| | - Yasmin Ayob
- Immunohematology Division, National Blood Center, Institute for Medical Research, Kuala Lumpur, Malaysia
| | - Narazah Mohd Yusoff
- Regenerative Medicine Cluster, Advanced Medical and Dental Institute, Universiti Sains Malaysia, Bertam, Pulau Penang, Malaysia
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16
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Hyodo S, Kakumura K, Takagi W, Hasegawa K, Yamaguchi Y. Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1381-95. [PMID: 25339681 DOI: 10.1152/ajpregu.00033.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
For adaptation to high-salinity marine environments, cartilaginous fishes (sharks, skates, rays, and chimaeras) adopt a unique urea-based osmoregulation strategy. Their kidneys reabsorb nearly all filtered urea from the primary urine, and this is an essential component of urea retention in their body fluid. Anatomical investigations have revealed the extraordinarily elaborate nephron system in the kidney of cartilaginous fishes, e.g., the four-loop configuration of each nephron, the occurrence of distinct sinus and bundle zones, and the sac-like peritubular sheath in the bundle zone, in which the nephron segments are arranged in a countercurrent fashion. These anatomical and morphological characteristics have been considered to be important for urea reabsorption; however, a mechanism for urea reabsorption is still largely unknown. This review focuses on recent progress in the identification and mapping of various pumps, channels, and transporters on the nephron segments in the kidney of cartilaginous fishes. The molecules include urea transporters, Na(+)/K(+)-ATPase, Na(+)-K(+)-Cl(-) cotransporters, and aquaporins, which most probably all contribute to the urea reabsorption process. Although research is still in progress, a possible model for urea reabsorption in the kidney of cartilaginous fishes is discussed based on the anatomical features of nephron segments and vascular systems and on the results of molecular mapping. The molecular anatomical approach thus provides a powerful tool for understanding the physiological processes that take place in the highly elaborate kidney of cartilaginous fishes.
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Affiliation(s)
- Susumu Hyodo
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, Kawshiwa, Chiba, Japan
| | - Keigo Kakumura
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, Kawshiwa, Chiba, Japan
| | - Wataru Takagi
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, Kawshiwa, Chiba, Japan
| | - Kumi Hasegawa
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, Kawshiwa, Chiba, Japan
| | - Yoko Yamaguchi
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, Kawshiwa, Chiba, Japan
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17
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Pitts RJ, Derryberry SL, Pulous FE, Zwiebel LJ. Antennal-expressed ammonium transporters in the malaria vector mosquito Anopheles gambiae. PLoS One 2014; 9:e111858. [PMID: 25360676 PMCID: PMC4216128 DOI: 10.1371/journal.pone.0111858] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 10/07/2014] [Indexed: 01/13/2023] Open
Abstract
The principal Afrotropical malaria vector mosquito, Anopheles gambiae remains a significant threat to human health. In this anthropophagic species, females detect and respond to a range of human-derived volatile kairomones such as ammonia, lactic acid, and other carboxylic acids in their quest for blood meals. While the molecular underpinnings of mosquito olfaction and host seeking are becoming better understood, many questions remain unanswered. In this study, we have identified and characterized two candidate ammonium transporter genes, AgAmt and AgRh50 that are expressed in the mosquito antenna and may contribute to physiological and behavioral responses to ammonia, which is an important host kairomone for vector mosquitoes. AgAmt transcripts are highly enhanced in female antennae while a splice variant of AgRh50 appears to be antennal-specific. Functional expression of AgAmt in Xenopus laevis oocytes facilitates inward currents in response to both ammonium and methylammonium, while AgRh50 is able to partially complement a yeast ammonium transporter mutant strain, validating their conserved roles as ammonium transporters. We present evidence to suggest that both AgAmt and AgRh50 are in vivo ammonium transporters that are important for ammonia sensitivity in An. gambiae antennae, either by clearing ammonia from the sensillar lymph or by facilitating sensory neuron responses to environmental exposure. Accordingly, AgAmt and AgRh50 represent new and potentially important targets for the development of novel vector control strategies.
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Affiliation(s)
- R. Jason Pitts
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Global Health, Nashville, Tennessee, United States of America
| | - Stephen L. Derryberry
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Fadi E. Pulous
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Laurence J. Zwiebel
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Global Health, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt Brain Institute, Program in Developmental Biology and Institute of Chemical Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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18
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ABO and Rhesus blood groups and risk of endometriosis in a French Caucasian population of 633 patients living in the same geographic area. BIOMED RESEARCH INTERNATIONAL 2014; 2014:618964. [PMID: 25243164 PMCID: PMC4160609 DOI: 10.1155/2014/618964] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 08/10/2014] [Indexed: 11/26/2022]
Abstract
Objectives. The identification of epidemiological factors increasing the risk of endometriosis could shorten the time to diagnosis. Specific blood groups may be more common in patients with endometriosis. Study Design. We designed a cross-sectional study of 633 Caucasian women living in the same geographic area. Study group included 311 patients with histologically proven endometriosis. Control group included 322 patients without endometriosis as checked during surgery. Frequencies of ABO and Rhesus groups in the study and control groups were compared using univariate and multivariate analyses. Results. We observed a higher proportion of Rh-negative women in the study group, as compared to healthy controls. Multivariate analysis showed that Rh-negative women are twice as likely to develop endometriosis (aOR = 1.90; 95% CI: 1.20–2.90). There was no significant difference in ABO group distribution between patients and controls. There was no difference when taking into account either the clinical forms (superficial endometriosis, endometrioma, and deep infiltration endometriosis) or the rAFS stages. Conclusion. Rh-negative women are twice as likely to develop endometriosis. Chromosome 1p, which contains the genes coding for the Rhesus, could also harbor endometriosis susceptibility genes.
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19
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Offre P, Kerou M, Spang A, Schleper C. Variability of the transporter gene complement in ammonia-oxidizing archaea. Trends Microbiol 2014; 22:665-75. [PMID: 25169021 DOI: 10.1016/j.tim.2014.07.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Revised: 07/17/2014] [Accepted: 07/30/2014] [Indexed: 12/19/2022]
Abstract
Ammonia-oxidizing archaea (AOA) are a widespread and abundant component of microbial communities in many different ecosystems. The extent of physiological differences between individual AOA is, however, unknown. Here, we compare the transporter gene complements of six AOA, from four different environments and two major clades, to assess their potential for substrate uptake and efflux. Each of the corresponding AOA genomes encode a unique set of transporters and although the composition of AOA transporter complements follows a phylogenetic pattern, few transporter families are conserved in all investigated genomes. A comparison of ammonia transporters encoded by archaeal and bacterial ammonia oxidizers highlights the variance among AOA lineages as well as their distinction from the ammonia-oxidizing bacteria, and suggests differential ecological adaptations.
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Affiliation(s)
- Pierre Offre
- University of Vienna, Department of Ecogenomics and Systems Biology, Archaea Biology and Ecogenomics Division, Althanstrasse 14, A-1090 Wien, Austria.
| | - Melina Kerou
- University of Vienna, Department of Ecogenomics and Systems Biology, Archaea Biology and Ecogenomics Division, Althanstrasse 14, A-1090 Wien, Austria
| | - Anja Spang
- Uppsala University, Department of Cell and Molecular Biology, Science for Life Laboratory, Box 596, SE-75123, Uppsala, Sweden
| | - Christa Schleper
- University of Vienna, Department of Ecogenomics and Systems Biology, Archaea Biology and Ecogenomics Division, Althanstrasse 14, A-1090 Wien, Austria.
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20
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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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21
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Characteristics of mammalian Rh glycoproteins (SLC42 transporters) and their role in acid-base transport. Mol Aspects Med 2013; 34:629-37. [PMID: 23506896 DOI: 10.1016/j.mam.2012.05.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 04/16/2012] [Indexed: 01/06/2023]
Abstract
The mammalian Rh glycoproteins belong to the solute transporter family SLC42 and include RhAG, present in red blood cells, and two non-erythroid members RhBG and RhCG that are expressed in various tissues, including kidney, liver, skin and the GI tract. The Rh proteins in the red blood cell form an "Rh complex" made up of one D-subunit, one CE-subunit and two RhAG subunits. The Rh complex has a well-known antigenic effect but also contributes to the stability of the red cell membrane. RhBG and RhCG are related to the NH4(+) transporters of the yeast and bacteria but their exact function is yet to be determined. This review describes the expression and molecular properties of these membrane proteins and their potential role as NH3/NH4(+) and CO2 transporters. The likelihood that these proteins transport gases such as CO2 or NH3 is novel and significant. The review also describes the physiological importance of these proteins and their relevance to human disease.
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22
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Li JY, Patterson M, Mikkola HKA, Lowry WE, Kurdistani SK. Dynamic distribution of linker histone H1.5 in cellular differentiation. PLoS Genet 2012; 8:e1002879. [PMID: 22956909 PMCID: PMC3431313 DOI: 10.1371/journal.pgen.1002879] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 06/21/2012] [Indexed: 12/31/2022] Open
Abstract
Linker histones are essential components of chromatin, but the distributions and functions of many during cellular differentiation are not well understood. Here, we show that H1.5 binds to genic and intergenic regions, forming blocks of enrichment, in differentiated human cells from all three embryonic germ layers but not in embryonic stem cells. In differentiated cells, H1.5, but not H1.3, binds preferentially to genes that encode membrane and membrane-related proteins. Strikingly, 37% of H1.5 target genes belong to gene family clusters, groups of homologous genes that are located in proximity to each other on chromosomes. H1.5 binding is associated with gene repression and is required for SIRT1 binding, H3K9me2 enrichment, and chromatin compaction. Depletion of H1.5 results in loss of SIRT1 and H3K9me2, increased chromatin accessibility, deregulation of gene expression, and decreased cell growth. Our data reveal for the first time a specific and novel function for linker histone subtype H1.5 in maintenance of condensed chromatin at defined gene families in differentiated human cells. In human cells, there are eleven subtypes of linker histones, five (H1.1–H1.5) of which are ubiquitously expressed in somatic cells. Somatic linker histones have been thought of as a group of similar proteins with redundant functions with few known differences among them. Our work uncovers for the first time a novel and unique role for the linker histone H1.5 (HIST1H1B). We found that H1.5, but not H1.3 (HIST1H1D), forms blocks of chromatin binding in genic and intergenic regions in differentiated human cells from all germ layers but not in embryonic stem cells. In genic regions, H1.5 binds to a large fraction of gene families that encode membrane associated proteins and are transcriptionally silent in a tissue-specific manner. H1.5 binding is associated with other repressive chromatin elements such as SIRT1 binding and H3K9me2 enrichment, and it negatively correlates with Pol II distribution. SIRT1 and H3K9me2 binding is dependent on H1.5, but not vice versa. H1.5 depletion in fibroblasts leads to increased chromatin accessibility at its target loci, altered cell cycle, and deregulation of gene expression. Our findings show that H1.5 has a dynamic distribution during human cell differentiation and is required for maintenance of proper gene expression in differentiated cells.
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Affiliation(s)
- Jing-Yu Li
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- Eli and Edythe Broad Centre of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, California, United States of America
| | - Michaela Patterson
- Department of Molecular, Cellular, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Hanna K. A. Mikkola
- Eli and Edythe Broad Centre of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Molecular, Cellular, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - William E. Lowry
- Eli and Edythe Broad Centre of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Molecular, Cellular, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Siavash K. Kurdistani
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- Eli and Edythe Broad Centre of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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23
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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: 87] [Impact Index Per Article: 7.3] [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.
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Affiliation(s)
- Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
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24
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Flatt JF, Musa RH, Ayob Y, Hassan A, Asidin N, Yahya NM, Mathlouthi R, Thornton N, Anstee DJ, Bruce LJ. Study of the D-- phenotype reveals erythrocyte membrane alterations in the absence of RHCE. Br J Haematol 2012; 158:262-273. [PMID: 22571328 DOI: 10.1111/j.1365-2141.2012.09149.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 03/27/2012] [Indexed: 02/04/2023]
Abstract
Red cells with the D-- phenotype do not express the RHCE protein because of mutations in both alleles of the RHCE gene. At present, little is known of the effect this has on the normal function of erythrocytes. In this study a group of five families belonging to a nomadic tribe in Malaysia were identified as carriers of the D-- haplotype. Analysis of homozygous individuals' genomic DNA showed two separate novel mutations. In four of the families, RHCE exons 1, 9 and 10 were present, while the 5th family possessed RHCE exons 1-3 and 10. Analysis of cDNA revealed hybrid transcripts, suggesting a gene conversion event with RHD, consistent with previously reported D-- mutations. Immunoblotting analysis of D-- erythrocyte membrane proteins found that Rh-associated glycoprotein (RHAG) migrates with altered electrophoretic mobility on sodium dodecyl sulphate polyacrylamide gel electrophoresis, consistent with increased glycosylation. Total amounts of Rh polypeptide in D-- membranes were comparable with controls, indicating that the exalted D antigen displayed by D-- red cells may be associated with altered surface epitope presentation. The adhesion molecules CD44 and CD47 are significantly reduced in D--. Together these results suggest that absence of RHCE polypeptide alters the structure and packing of the band 3/Rh macrocomplex.
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Affiliation(s)
- Joanna F Flatt
- Bristol Institute for Transfusion Sciences, N.H.S. Blood and Transplant, Filton, Bristol, UK
| | - Rozi H Musa
- Immunohaematology Division, National Blood Centre, Kuala Lumpur, Malaysia
| | - Yasmin Ayob
- Immunohaematology Division, National Blood Centre, Kuala Lumpur, Malaysia
| | - Afifah Hassan
- Immunohaematology Division, National Blood Centre, Kuala Lumpur, Malaysia
| | - Norhanim Asidin
- Immunohaematology Division, National Blood Centre, Kuala Lumpur, Malaysia
| | - Nurul M Yahya
- Immunohaematology Division, National Blood Centre, Kuala Lumpur, Malaysia
| | - Rosalind Mathlouthi
- International Blood Group Reference Laboratory, N.H.S. Blood and Transplant, Filton, Bristol, UK
| | - Nicole Thornton
- International Blood Group Reference Laboratory, N.H.S. Blood and Transplant, Filton, Bristol, UK
| | - David J Anstee
- Bristol Institute for Transfusion Sciences, N.H.S. Blood and Transplant, Filton, Bristol, UK
| | - Lesley J Bruce
- Bristol Institute for Transfusion Sciences, N.H.S. Blood and Transplant, Filton, Bristol, UK
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McGann PT, Despotovic JM, Howard TA, Ware RE. A novel laboratory technique demonstrating the influences of RHD zygosity and the RhCcEe phenotype on erythrocyte D antigen expression. Am J Hematol 2012; 87:266-71. [PMID: 22121029 DOI: 10.1002/ajh.22254] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 09/21/2011] [Accepted: 11/08/2011] [Indexed: 11/11/2022]
Abstract
D antigen is the most immunogenic and clinically relevant antigen within the complex Rh blood group system. Variability of D antigen expression was first described decades ago but has rarely been investigated quantitatively, particularly in the context of RHD zygosity along with RhCcEe serological phenotype. With IRB approval, 107 deidentified blood samples were analyzed. Rh phenotypes were determined serologically by saline technique using monoclonal antibodies against D, C, c, E, and e antigens. RHD zygosity was determined using both PCR-restriction fragment length polymorphisms and quantitative real-time PCR techniques. A novel and robust method was developed for quantitation of erythrocyte D antigen sites using calibrated microspheres and flow cytometry, allowing correlation of D antigen density with RHD zygosity and expression of Rh CcEe antigens. Subjects homozygous for RHD expressed nearly twice the number of D antigen sites compared with RHD hemizygotes (33,560 ± 8,222 for DD versus 17,720 ± 4,471 for Dd, P < 0.0001). Expression of c or E antigens was associated with significantly increased erythrocyte D antigen expression, whereas presence of C or e antigens reduced expression. These data and this novel quantitation method will be important for future studies investigating the clinical relevance of D antigen variability.
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Affiliation(s)
- Patrick T McGann
- Baylor International Hematology Center of Excellence and the Texas Children's Center for Global Health, Houston, Texas, USA.
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Genetet S, Ripoche P, Picot J, Bigot S, Delaunay J, Armari-Alla C, Colin Y, Mouro-Chanteloup I. Human RhAG ammonia channel is impaired by the Phe65Ser mutation in overhydrated stomatocytic red cells. Am J Physiol Cell Physiol 2011; 302:C419-28. [PMID: 22012326 DOI: 10.1152/ajpcell.00092.2011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In red cells, Rh-associated glycoprotein (RhAG) acts as an ammonia channel, as demonstrated by stopped-flow analysis of ghost intracellular pH (pH(i)) changes. Recently, overhydrated hereditary stomatocytosis (OHSt), a rare dominantly inherited hemolytic anemia, was found to be associated with a mutation (Phe65Ser or Ile61Arg) in RHAG. Ghosts from the erythrocytes of four of the OHSt patients with a Phe65Ser mutation were resealed with a pH-sensitive probe and submitted to ammonium gradients. Alkalinization rate constants, reflecting NH(3) transport through the channel and NH(3) diffusion unmediated by RhAG, were deduced from time courses of fluorescence changes. After subtraction of the constant value found for Rh(null) lacking RhAG, we observed that alkalinization rate constant values decreased ∼50% in OHSt compared with those of controls. Similar RhAG expression levels were found in control and OHSt. Since half of the expressed RhAG in OHSt most probably corresponds to the mutated form of RhAG, as expected from the OHSt heterozygous status, this dramatic decrease can be therefore related to the loss of function of the Phe65Ser-mutated RhAG monomer.
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Patnaik SK, Blumenfeld OO. Patterns of human genetic variation inferred from comparative analysis of allelic mutations in blood group antigen genes. Hum Mutat 2011; 32:263-71. [PMID: 21312314 DOI: 10.1002/humu.21430] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 11/30/2010] [Indexed: 12/15/2022]
Abstract
Comparative analysis of allelic variation of a gene sheds light on the pattern and process of its diversification at the population level. Gene families for which a large number of allelic forms have been verified by sequencing provide a useful resource for such studies. In this regard, human blood group-encoding genes are unique in that differences of cell surface traits among individuals and populations can be readily detected by serological screening, and correlation between the variant cell surface phenotype and the genotype is, in most cases, unequivocal. Here, we perform a comprehensive analysis of allelic forms, compiled in the Blood Group Antigen Gene Mutation database, of ABO, RHD/CE, GYPA/B/E and FUT1/2 gene families that encode the ABO, RH, MNS, and H/h blood group system antigens, respectively. These genes are excellent illustrative examples showing distinct mutational patterns among the alleles, and leading to speculation on how their origin may have been driven by recurrent but different molecular mechanisms. We illustrate how alignment of alleles of a gene may provide an additional insight into the DNA variation process and its pathways, and how this approach may serve to catalog alleles of a gene, simplifying the task and content of mutation databases.
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Affiliation(s)
- Santosh Kumar Patnaik
- Department of Thoracic Surgery, Roswell Park Cancer Institute, Buffalo, New York, USA
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28
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Abstract
Rhesus is the clinically most important protein-based blood group system. It represents the largest number of antigens and the most complex genetics of the 30 known blood group systems. The RHD and RHCE genes are strongly homologous. Some genetic complexity is explained by their close chromosomal proximity and unusual orientation, with their tail ends facing each other. The antigens are expressed by the RhD and the RhCE proteins. Rhesus exemplifies the correlation of genotype and phenotype, facilitating the understanding of general genetic mechanisms. For clinical purposes, genetic diagnostics of Rhesus antigens will improve the cost-effective development of transfusion medicine.
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Affiliation(s)
- Willy A Flegel
- Department of Transfusion Medicine, Clinical Center, National Institutes of Health, Bethesda, MD 20892, United States.
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29
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Kelly T, Rose CR. Ammonium influx pathways into astrocytes and neurones of hippocampal slices. J Neurochem 2010; 115:1123-36. [DOI: 10.1111/j.1471-4159.2010.07009.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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30
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Michele Nawata C, Hirose S, Nakada T, Wood CM, Kato A. Rh glycoprotein expression is modulated in pufferfish (Takifugu rubripes) during high environmental ammonia exposure. J Exp Biol 2010; 213:3150-60. [DOI: 10.1242/jeb.044719] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
SUMMARY
Rhesus (Rh) protein involvement in ammonia transport processes in freshwater fish has received considerable attention; however, parallel investigations in seawater species are scant. We exposed pufferfish to high environmental ammonia (HEA; 1 and 5 mmol l–1 NH4HCO3) and evaluated the patterns of ammonia excretion and gill Rh mRNA and protein expression. Gill H+-ATPase, NHE1, NHE2, NHE3, Na+/K+-ATPase (NKA), Na+/K+/2Cl– co-transporter (NKCC1) mRNA, H+-ATPase activity, NKA protein and activity, were also quantified. Activation of NKA by NH4+ was demonstrated in vitro. The downregulation of Rhbg mRNA and simultaneous upregulations of Rhcg1, H+-ATPase, NHE3, NKA, NKCC1 mRNA, H+-ATPase activity, and NKA protein and activity levels suggested that during HEA, ammonia excretion was mediated mainly by mitochondria-rich cells (MRCs) driven by NKA with basolateral NH4+ entry via NKA and/or NKCC1, and apical NH3 extrusion via Rhcg1. Reprotonation of NH3 by NHE3 and/or H+-ATPase would minimise back flux through the Rh channels. Downregulated Rhbg and Rhag mRNA observed in the gill during HEA suggests a coordinated protective response to minimise the influx of external ammonia via the pavement cells and pillar cells, respectively, while routing ammonia excretion through the MRCs. Exposure to hypercapnia (1% CO2 in air) resulted in downregulated gill and erythrocyte Rhag mRNA. Surprisingly, Rhag, Rhbg, Rhcg1 and Rhcg2 proteins responded to both hypercapnia and HEA with changes in their apparent molecular masses. A dual NH3/CO2 transport function of the pufferfish Rh proteins is therefore suggested. The results support and extend an earlier proposed model of pufferfish gill ammonia excretion that was based on immunolocalisation of the Rh proteins. Passive processes and/or Rhbg and Rhcg2 in the pavement cells may maintain basal levels of plasma ammonia but elevated levels may require active excretion via NKA and Rhcg1 in the MRCs.
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Affiliation(s)
- C. Michele Nawata
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
| | - Shigehisa Hirose
- Department of Biological Sciences, Tokyo Institute of Technology, Yokohama, 226-8501, Japan
| | - Tsutomu Nakada
- Department of Molecular Pharmacology, Shinshu University School of Medicine, Matsumoto, 390-8621, Japan
| | - Chris M. Wood
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
| | - Akira Kato
- Department of Biological Sciences, Tokyo Institute of Technology, Yokohama, 226-8501, Japan
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