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Bueno E, Mania D, Mesa S, Bedmar EJ, Frostegård Å, Bakken LR, Delgado MJ. Regulation of the Emissions of the Greenhouse Gas Nitrous Oxide by the Soybean Endosymbiont Bradyrhizobium diazoefficiens. Int J Mol Sci 2022; 23:1486. [PMID: 35163408 PMCID: PMC8836242 DOI: 10.3390/ijms23031486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/20/2022] [Accepted: 01/20/2022] [Indexed: 11/21/2022] Open
Abstract
The greenhouse gas nitrous oxide (N2O) has strong potential to drive climate change. Soils are a major source of N2O, with microbial nitrification and denitrification being the primary processes involved in such emissions. The soybean endosymbiont Bradyrhizobium diazoefficiens is a model microorganism to study denitrification, a process that depends on a set of reductases, encoded by the napEDABC, nirK, norCBQD, and nosRZDYFLX genes, which sequentially reduce nitrate (NO3-) to nitrite (NO2-), nitric oxide (NO), N2O, and dinitrogen (N2). In this bacterium, the regulatory network and environmental cues governing the expression of denitrification genes rely on the FixK2 and NnrR transcriptional regulators. To understand the role of FixK2 and NnrR proteins in N2O turnover, we monitored real-time kinetics of NO3-, NO2-, NO, N2O, N2, and oxygen (O2) in a fixK2 and nnrR mutant using a robotized incubation system. We confirmed that FixK2 and NnrR are regulatory determinants essential for NO3- respiration and N2O reduction. Furthermore, we demonstrated that N2O reduction by B. diazoefficiens is independent of canonical inducers of denitrification, such as the nitrogen oxide NO3-, and it is negatively affected by acidic and alkaline conditions. These findings advance the understanding of how specific environmental conditions and two single regulators modulate N2O turnover in B. diazoefficiens.
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Affiliation(s)
- Emilio Bueno
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain; (S.M.); (E.J.B.)
| | - Daniel Mania
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Aas, Norway; (D.M.); (Å.F.); (L.R.B.)
| | - Socorro Mesa
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain; (S.M.); (E.J.B.)
| | - Eulogio J. Bedmar
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain; (S.M.); (E.J.B.)
| | - Åsa Frostegård
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Aas, Norway; (D.M.); (Å.F.); (L.R.B.)
| | - Lars R. Bakken
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Aas, Norway; (D.M.); (Å.F.); (L.R.B.)
| | - María J. Delgado
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain; (S.M.); (E.J.B.)
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Gao Y, Mania D, Mousavi SA, Lycus P, Arntzen MØ, Woliy K, Lindström K, Shapleigh JP, Bakken LR, Frostegård Å. Competition for electrons favours N 2 O reduction in denitrifying Bradyrhizobium isolates. Environ Microbiol 2021; 23:2244-2259. [PMID: 33463871 DOI: 10.1111/1462-2920.15404] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/21/2020] [Accepted: 01/15/2021] [Indexed: 11/28/2022]
Abstract
Bradyrhizobia are common members of soil microbiomes and known as N2 -fixing symbionts of economically important legumes. Many are also denitrifiers, which can act as sinks or sources for N2 O. Inoculation with compatible rhizobia is often needed for optimal N2 -fixation, but the choice of inoculant may have consequences for N2 O emission. Here, we determined the phylogeny and denitrification capacity of Bradyrhizobium strains, most of them isolated from peanut-nodules. Analyses of genomes and denitrification end-points showed that all were denitrifiers, but only ~1/3 could reduce N2 O. The N2 O-reducing isolates had strong preference for N2 O- over NO3 - -reduction. Such preference was also observed in a study of other bradyrhizobia and tentatively ascribed to competition between the electron pathways to Nap (periplasmic NO3 - reductase) and Nos (N2 O reductase). Another possible explanation is lower abundance of Nap than Nos. Here, proteomics revealed that Nap was instead more abundant than Nos, supporting the hypothesis that the electron pathway to Nos outcompetes that to Nap. In contrast, Paracoccus denitrificans, which has membrane-bond NO3 - reductase (Nar), reduced N2 O and NO3 - simultaneously. We propose that the control at the metabolic level, favouring N2 O reduction over NO3 - reduction, applies also to other denitrifiers carrying Nos and Nap but lacking Nar.
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Affiliation(s)
- Yuan Gao
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Aas, Norway
| | - Daniel Mania
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Aas, Norway
| | - Seyed Abdollah Mousavi
- Ecosystems and Environment Research programme, Faculty of Biological and Environmental Sciences, and Helsinki Institute of Sustainability Science (HELSUS), University of Helsinki, Finland
| | - Pawel Lycus
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Aas, Norway
| | - Magnus Ø Arntzen
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Aas, Norway
| | - Kedir Woliy
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Aas, Norway
| | - Kristina Lindström
- Ecosystems and Environment Research programme, Faculty of Biological and Environmental Sciences, and Helsinki Institute of Sustainability Science (HELSUS), University of Helsinki, Finland
| | | | - Lars R Bakken
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Aas, Norway
| | - Åsa Frostegård
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Aas, Norway
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Cucca A, Mania D, Sharma K, Acosta I, Berberian M, Beheshti M, Biagioni M, Droby A, Di Rocco A, Ghilardi M, Inglese M, Rizzo J, Feigin A. Neural correlates of visuospatial dysfunction in Parkinson's Disease: A multimodal biomarker study. Parkinsonism Relat Disord 2020. [DOI: 10.1016/j.parkreldis.2020.06.163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Keuschnig C, Gorfer M, Li G, Mania D, Frostegård Å, Bakken L, Larose C. NO and N 2 O transformations of diverse fungi in hypoxia: evidence for anaerobic respiration only in Fusarium strains. Environ Microbiol 2020; 22:2182-2195. [PMID: 32157782 DOI: 10.1111/1462-2920.14980] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 02/21/2020] [Accepted: 03/07/2020] [Indexed: 11/30/2022]
Abstract
Fungal denitrification is claimed to produce non-negligible amounts of N2 O in soils, but few tested species have shown significant activity. We hypothesized that denitrifying fungi would be found among those with assimilatory nitrate reductase, and tested 20 such batch cultures for their respiratory metabolism, including two positive controls, Fusarium oxysporum and Fusarium lichenicola, throughout the transition from oxic to anoxic conditions in media supplemented with NO 2 - . Enzymatic reduction of NO 2 - (NIR) and NO (NOR) was assessed by correcting measured NO- and N2 O-kinetics for abiotic NO- and N2 O-production (sterile controls). Significant anaerobic respiration was only confirmed for the positive controls and for two of three Fusarium solani cultures. The NO kinetics in six cultures showed NIR but not NOR activity, observed through the accumulation of NO. Others had NOR but not NIR activity, thus reducing abiotically produced NO to N2 O. The presence of candidate genes (nirK and p450nor) was confirmed in the positive controls, but not in some of the NO or N2 O accumulating cultures. Based on our results, we conclude that only the Fusarium cultures were able to sustain anaerobic respiration and produced low amounts of N2 O as a response to an abiotic NO production from the medium.
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Affiliation(s)
- Christoph Keuschnig
- Environmental Microbial Genomics, Laboratoire Ampère, CNRS UMR 5005, Ecole Centrale de Lyon, Université de Lyon, 69134, Ecully Cedex, France
| | - Markus Gorfer
- Bioresources, AIT Austrian Institute of Technology GmbH, Tulln, Austria
| | - Guofen Li
- Bioresources, AIT Austrian Institute of Technology GmbH, Tulln, Austria
| | - Daniel Mania
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, 1432, Aas, Norway
| | - Åsa Frostegård
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, 1432, Aas, Norway
| | - Lars Bakken
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, 1432, Aas, Norway
| | - Catherine Larose
- Environmental Microbial Genomics, Laboratoire Ampère, CNRS UMR 5005, Ecole Centrale de Lyon, Université de Lyon, 69134, Ecully Cedex, France
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Mania D, Woliy K, Degefu T, Frostegård Å. A common mechanism for efficient N2O reduction in diverse isolates of nodule‐forming bradyrhizobia. Environ Microbiol 2019; 22:17-31. [DOI: 10.1111/1462-2920.14731] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 07/02/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Daniel Mania
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life Science ås Norway
| | - Kedir Woliy
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life Science ås Norway
| | - Tulu Degefu
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life Science ås Norway
- International Crops Research Institute for the Semi‐Arid Tropics Addis Ababa Ethiopia
| | - åsa Frostegård
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life Science ås Norway
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Mania D, Heylen K, van Spanning RJM, Frostegård Å. Regulation of nitrogen metabolism in the nitrate-ammonifying soil bacteriumBacillus viretiand evidence for its ability to grow using N2O as electron acceptor. Environ Microbiol 2016; 18:2937-50. [DOI: 10.1111/1462-2920.13124] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 11/03/2015] [Accepted: 11/03/2015] [Indexed: 12/28/2022]
Affiliation(s)
- Daniel Mania
- Department of Chemistry, Biotechnology and Food Science; Norwegian University of Life Science; Ås Norway
| | - Kim Heylen
- Laboratory of Microbiology; Department of Biochemistry and Microbiology; University of Ghent; Gent Belgium
| | - Rob J. M. van Spanning
- Department of Molecular Cell Biology; Faculty of Earth and Life Science; VU University; Amsterdam The Netherlands
| | - Åsa Frostegård
- Department of Chemistry, Biotechnology and Food Science; Norwegian University of Life Science; Ås Norway
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Bueno E, Mania D, Frostegard Ǻ, Bedmar EJ, Bakken LR, Delgado MJ. Anoxic growth of Ensifer meliloti 1021 by N2O-reduction, a potential mitigation strategy. Front Microbiol 2015; 6:537. [PMID: 26074913 PMCID: PMC4443521 DOI: 10.3389/fmicb.2015.00537] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 05/15/2015] [Indexed: 01/17/2023] Open
Abstract
Denitrification in agricultural soils is a major source of N2O. Legume crops enhance N2O emission by providing N-rich residues, thereby stimulating denitrification, both by free-living denitrifying bacteria and by the symbiont (rhizobium) within the nodules. However, there are limited data concerning N2O production and consumption by endosymbiotic bacteria associated with legume crops. It has been reported that the alfalfa endosymbiont Ensifer meliloti strain 1021, despite possessing and expressing the complete set of denitrification enzymes, is unable to grow via nitrate respiration under anoxic conditions. In the present study, we have demonstrated by using a robotized incubation system that this bacterium is able to grow through anaerobic respiration of N2O to N2. N2O reductase (N2OR) activity was not dependent on the presence of nitrogen oxyanions or NO, thus the expression could be induced by oxygen depletion alone. When incubated at pH 6, E. meliloti was unable to reduce N2O, corroborating previous observations found in both, extracted soil bacteria and Paracoccus denitrificans pure cultures, where expression of functional N2O reductase is difficult at low pH. Furthermore, the presence in the medium of highly reduced C-substrates, such as butyrate, negatively affected N2OR activity. The emission of N2O from soils can be lowered if legumes plants are inoculated with rhizobial strains overexpressing N2O reductase. This study demonstrates that strains like E. meliloti 1021, which do not produce N2O but are able to reduce the N2O emitted by other organisms, could act as even better N2O sinks.
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Affiliation(s)
- Emilio Bueno
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Spanish Council for Scientific Research Granada, Spain
| | - Daniel Mania
- Department of Environmental Sciences, Norwegian University of Life Sciences Ǻs, Norway
| | - Ǻsa Frostegard
- Department of Environmental Sciences, Norwegian University of Life Sciences Ǻs, Norway
| | - Eulogio J Bedmar
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Spanish Council for Scientific Research Granada, Spain
| | - Lars R Bakken
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences Ǻs, Norway
| | - Maria J Delgado
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Spanish Council for Scientific Research Granada, Spain
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Mania D, Heylen K, van Spanning RJM, Frostegård Å. The nitrate-ammonifying andnosZ-carrying bacteriumBacillus viretiis a potent source and sink for nitric and nitrous oxide under high nitrate conditions. Environ Microbiol 2014; 16:3196-210. [DOI: 10.1111/1462-2920.12478] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/13/2014] [Accepted: 03/24/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Daniel Mania
- Department of Chemistry, Biotechnology and Food Science; Norwegian University of Life Science; Ås Norway
| | - Kim Heylen
- Laboratory of Microbiology; Department of Biochemistry and Microbiology; University of Ghent; Gent Belgium
| | - Rob J. M. van Spanning
- Department of Molecular Cell Biology; Faculty of Earth and Life Science; VU University; Amsterdam The Netherlands
| | - Åsa Frostegård
- Department of Chemistry, Biotechnology and Food Science; Norwegian University of Life Science; Ås Norway
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Luckmann M, Mania D, Kern M, Bakken LR, Frostegård Å, Simon J. Production and consumption of nitrous oxide in nitrate-ammonifying Wolinella succinogenes cells. Microbiology (Reading) 2014; 160:1749-1759. [PMID: 24781903 DOI: 10.1099/mic.0.079293-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Global warming is moving more and more into the public consciousness. Besides the commonly mentioned carbon dioxide and methane, nitrous oxide (N2O) is a powerful greenhouse gas in addition to its contribution to depletion of stratospheric ozone. The increasing concern about N2O emission has focused interest on underlying microbial energy-converting processes and organisms harbouring N2O reductase (NosZ), such as denitrifiers and ammonifiers of nitrate and nitrite. Here, the epsilonproteobacterial model organism Wolinella succinogenes is investigated with regard to its capacity to produce and consume N2O during growth by anaerobic nitrate ammonification. This organism synthesizes an unconventional cytochrome c nitrous oxide reductase (cNosZ), which is encoded by the first gene of an atypical nos gene cluster. However, W. succinogenes lacks a nitric oxide (NO)-producing nitrite reductase of the NirS- or NirK-type as well as an NO reductase of the Nor-type. Using a robotized incubation system, the wild-type strain and suitable mutants of W. succinogenes that either produced or lacked cNosZ were analysed as to their production of NO, N2O and N2 in both nitrate-sufficient and nitrate-limited growth medium using formate as electron donor. It was found that cells growing in nitrate-sufficient medium produced small amounts of N2O, which derived from nitrite and, most likely, from the presence of NO. Furthermore, cells employing cNosZ were able to reduce N2O to N2. This reaction, which was fully inhibited by acetylene, was also observed after adding N2O to the culture headspace. The results indicate that W. succinogenes cells are competent in N2O and N2 production despite being correctly grouped as respiratory nitrate ammonifiers. N2O production is assumed to result from NO detoxification and nitrosative stress defence, while N2O serves as a terminal electron acceptor in anaerobic respiration. The ecological implications of these findings are discussed.
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Affiliation(s)
- Monique Luckmann
- Microbial Energy Conversion and Biotechnology, Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, 64287 Darmstadt, Germany
| | - Daniel Mania
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Chr Falsens vei 1, N1432 Ås, Norway
| | - Melanie Kern
- Microbial Energy Conversion and Biotechnology, Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, 64287 Darmstadt, Germany
| | - Lars R Bakken
- Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, PO Box 5003, N1432 Ås, Norway
| | - Åsa Frostegård
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Chr Falsens vei 1, N1432 Ås, Norway
| | - Jörg Simon
- Microbial Energy Conversion and Biotechnology, Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, 64287 Darmstadt, Germany
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Takeshita N, Mania D, Herrero de Vega S, Ishitsuka Y, Nienhaus GU, Podolski M, Howard J, Fischer R. The cell end marker TeaA and the microtubule polymerase AlpA contribute to microtubule guidance at the hyphal tip cortex of Aspergillus nidulans for polarity maintenance. J Cell Sci 2013; 126:5400-11. [DOI: 10.1242/jcs.129841] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In the absence of landmark proteins, hyphae of Aspergillus nidulans lose their direction of growth and show a zigzag growth pattern. Here, we show that the cell end marker protein TeaA is important for localizing the growth machinery at hyphal tips. The central position of TeaA at the tip correlated with the convergence of the microtubule (MT) ends to a single point. Conversely, in the absence of TeaA, the MTs often failed to converge to a single point at the cortex. Further analysis suggested a functional connection between TeaA and AlpA (MT polymerase XMAP215 orthologue) for proper regulation of MT growth at hyphal tips. AlpA localized at MT plus ends, and bimolecular fluorescence complementation assays suggested that it interacted with TeaA after MT plus ends reached the tip cortex. In vitro MT polymerization assays showed that AlpA promoted MT growth up to seven-fold. Addition of the C-terminal region of TeaA increased the catastrophe frequency of the MTs. Thus, the control of the AlpA activity through TeaA may be a novel principle for MT growth regulation after reaching the cortex. In addition, we present evidence that the curvature of hyphal tips also could be involved in the control of MT growth at hyphal tips.
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Englert HC, Gerlach U, Goegelein H, Hartung J, Heitsch H, Mania D, Scheidler S. Cardioselective K(ATP) channel blockers derived from a new series of m-anisamidoethylbenzenesulfonylthioureas. J Med Chem 2001; 44:1085-98. [PMID: 11297455 DOI: 10.1021/jm000985v] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sulfonylthioureas exhibiting cardioselective blockade of ATP-sensitive potassium channels (K(ATP) channels) were discovered by stepwise structural variations of the antidiabetic sulfonylurea glibenclamide. As screening assays, reversal of rilmakalim-induced shortening of the cardiac action potential in guinea pig papillary muscles was used to probe for activity on cardiac K(ATP) channels as the target, and membrane depolarization in CHO cells stably transfected with hSUR1/hKir6.2 was used to probe for unwanted side effects on pancreatic K(ATP) channels. Changing glibenclamide's para-arrangement of substituents in the central aromatic ring to a meta-pattern associated with size reduction of the substituent at the terminal nitrogen atom of the sulfonylurea moiety was found to achieve cardioselectivity. An additional change from a sulfonylurea moiety to a sulfonylthiourea moiety along with an appropriate substituent in the ortho-position of the central aromatic system was a successful strategy to further improve potency on the cardiac K(ATP) channel. Among this series of sulfonylthioureas HMR1883, 1-[5-[2-(5-chloro-o-anisamido)ethyl]-2-methoxyphenyl]sulfonyl-3-methylthiourea, and its sodium salt HMR1098 were selected for development and represent a completely new therapeutic approach toward the prevention of life-threatening arrhythmias and sudden cardiac death in patients with coronary heart disease.
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Affiliation(s)
- H C Englert
- Medicinal Chemistry, Aventis Pharma Deutschland GmbH, D-65926 Frankfurt/Main, Germany.
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Abstract
The Middle Pleistocene site at Bilzingsleben is being excavated by the Forschungsstelle Bilzingsleben, FSU Jena. It is a living floor with structures of settlement and a great number of Lower Palaeolithic cultural remains. So far, 28 human skull fragments have been discovered, which can be reconstructed into two individual skulls. Recently, the right mandible has also been discovered (Bilzingsleben E7). Morphological comparisons indicate that there is a great similarity to the mandibles of HI and BI of Sinanthropus. A strong likeness to Arago II and XIII was also discovered. There are various different archaic features which assign the Bilzingsleben mandible and the two skulls to the advanced Homo erectus.
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Affiliation(s)
- E Vlcek
- National Museum, Prague, Czech Republic
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Lohrmann E, Burhoff I, Nitschke RB, Lang HJ, Mania D, Englert HC, Hropot M, Warth R, Rohm W, Bleich M. A new class of inhibitors of cAMP-mediated Cl- secretion in rabbit colon, acting by the reduction of cAMP-activated K+ conductance. Pflugers Arch 1995; 429:517-30. [PMID: 7617442 DOI: 10.1007/bf00704157] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Previously we have shown that arylaminobenzoates like 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB), which are very potent inhibitors of NaCl absorption in the thick ascending limb of the loop of Henle, are only poor inhibitors of the cAMP-mediated secretion of NaCl in rat colon. This has prompted our search for more potent inhibitors of NaCl secretion in the latter system. The chromanole compound 293 B inhibited the equivalent short-circuit current (Isc) induced by prostaglandin E2 (n = 7), vasoactive intestinal polypeptide (VIP, n = 5), adenosine (n = 3), cholera toxin (n = 4) and cAMP (n = 6), but not by ionomycin (n = 5) in distal rabbit colon half maximally (IC50) at 2 mumol/l from the mucosal and at 0.7 mumol/l from the serosal side. The inhibition was reversible and paralleled by a significant increase in transepithelial membrane resistance [e.g. in the VIP series from 116 +/- 16 omega.cm2 to 136 +/- 21 omega.cm2 (n = 5)]. A total of 25 derivatives of 293 B were examined and structure activity relations were obtained. It was shown that the racemate 293 B was the most potent compound within this group and that its effect was due to the enantiomer 434 B which acted half maximally at 0.25 mumol/l. Further studies in isolated in vitro perfused colonic crypts revealed that 10 mumol/l 293 B had no effect on the membrane voltage across the basolateral membrane (Vbl) in non-stimulated crypt cells: -69 +/- 3 mV versus -67 +/- 3 mV (n = 10), whilst in the same cells 1 mmol/l Ba2+ depolarised Vbl significantly. However, 293 B depolarised Vbl significantly in the presence of 1 mumol/l forskolin: -45 +/- 4 mV versus -39 +/- 5 mV (n = 7). Similar results were obtained with 0.1 mmol/l adenosine. 293 B depolarised Vbl from -40 +/- 5 mV to -30 +/- 4 mV (n = 19). This was paralleled by an increase in the fractional resistance of the basolateral membrane. VIP had a comparable effect. The hyperpolarisation induced by 0.1 mmol ATP was not influenced by 10 mumol/l 293 B: -75 +/- 6 mV versus -75 +/- 6 mV (n = 6). Also 293 B had no effect on basal K+ conductance (n = 4). Hence, we conclude that 293 B inhibits the K+ conductance induced by cAMP. This conductance is apparently relevant for Cl- secretion and the basal K+ conductance is insufficient to support secretion.
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Affiliation(s)
- E Lohrmann
- Physiologisches Institut der Albert-Ludwigs-Universität, Freiburg, Germany
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15
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Affiliation(s)
- D Mania
- Forschungsstelle Bilzingsleben der Universität, Jena
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Mania D, Mania U, Vlcek E. Latest Finds of Skull Remains of Homo erectus from Bilzingsleben (Thuringia). Naturwissenschaften 1994. [DOI: 10.1007/s001140050042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Linz W, Klaus E, Albus U, Becker R, Mania D, Englert HC, Schölkens BA. Cardiovascular effects of the novel potassium channel opener (3S,4R)-3-hydroxy-2,2-dimethyl-4-(2-oxo- 1-pyrrolidinyl)-6-phenylsulfonylchromane hemihydrate. Arzneimittelforschung 1992; 42:1180-5. [PMID: 1472138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cardiovascular effects of the novel potassium channel opener (3S,4R)-3-hydroxy-2,2-dimethyl-4-(2-oxo-1-pyrrolidinyl)-6- phenylsulfonylchromane hemihydrate (Hoe 234, CAS 132014-21-2) were investigated in rats, dogs and monkeys. In all species and independent of the route of administration Hoe 234 lowered systemic blood pressure accompanied with increases in heart rate. In rats after intravenous (i.v.) application Hoe 234 was 3 times more potent than cromakalim and its effects were reduced by pretreatment with the potassium channel blocker glibenclamide. Following intraduodenal application again Hoe 234 was more potent but mean arterial blood pressure (MAP) decreased more slowly and maximal effects were obtained later than after cromakalim. Oral administration of either single or repeated doses, however, revealed a somewhat higher potency for cromakalim. In anesthetized dogs Hoe 234 i.v. reduced MAP more potently than cromakalim whereas changes in heart rate were less pronounced. Cardiac output was increased and total peripheral resistance decreased for either agent. These results show that Hoe 234 is a novel potassium channel opener lowering blood pressure in animals due to peripheral vasodilation. It compares favourable with known potassium channel openers except for oral administration.
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Affiliation(s)
- W Linz
- Hoechst Aktiengesellschaft, Frankfurt/Main, Fed. Rep. of Germany
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Klaus E, Englert H, Hropot M, Mania D, Zwergel U. K+-channeI-openers inhibit the KCl-imduced phasic-rhythmic contractions in the upper urinary tract. Eur J Pharmacol 1990. [DOI: 10.1016/0014-2999(90)92461-q] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
Two analogues of the loop diuretics furosemide and bumetanide have been identified as differential inhibitors of KCl and NaKCl cotransport systems, assayed by measuring K+ influx in 'young' human red cells. H25 inhibited both NaKCl and KCl cotransport, with I50% values of 0.03 and 30 microM respectively; H74 had no effect on NaKCl cotransport, even at 0.3 mM, but inhibited KCl cotransport with an I50% of 75 microM. These compounds are therefore useful for resolving the two transport systems.
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Affiliation(s)
- J C Ellory
- Department of Physiology, University of Oxford, UK
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