1
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Lew B, Meir A, Khan AA, Khan MA, Tarre S, Green M. Ammonia gas treatment in low cost biological reactor. Bioresour Technol 2024; 391:129949. [PMID: 37926359 DOI: 10.1016/j.biortech.2023.129949] [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] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/20/2023] [Accepted: 10/28/2023] [Indexed: 11/07/2023]
Abstract
Ammonia gas contributes to a number of environmental and human health concerns. The use of chalk, a cheap alkalinity source may reduce costs for biological systems. This research studies a closed liquid flow reactor to treat ammonia gas using chalk as biomass media and alkalinity source with high value calcium nitrate fertilizer production. The proposed reactor showed complete ammonia gas removal at high rate (500 mg N/L/day) and with low cost; where chalk dissolution and ammonia gas absorption contributed to alkalinity in the water for nitrification. High calcium ion concentration (up to 10,000 mg Ca2+ as CaCO3/L) showed only minor effects on ammonia absorption and nitrification rate.
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Affiliation(s)
- B Lew
- Department of Civil Eng, Ariel University, Israel.
| | - A Meir
- Faculty of Civil and Environmental Engineering, Technion, Israel
| | - A A Khan
- Department of Civil Engineering Jamia Millia Islamia (A Central University), New Delhi, India
| | - M A Khan
- Centre for Rural Development and Technology, Indian Institute of Technology Delhi, Delhi, India
| | - S Tarre
- Faculty of Civil and Environmental Engineering, Technion, Israel
| | - M Green
- Faculty of Civil and Environmental Engineering, Technion, Israel
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2
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Meir A, Raina VB, Rivera CE, Marie L, Symington LS, Greene EC. The separation pin distinguishes the pro- and anti-recombinogenic functions of Saccharomyces cerevisiae Srs2. Nat Commun 2023; 14:8144. [PMID: 38065943 PMCID: PMC10709652 DOI: 10.1038/s41467-023-43918-4] [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] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 11/23/2023] [Indexed: 12/18/2023] Open
Abstract
Srs2 is an Sf1a helicase that helps maintain genome stability in Saccharomyces cerevisiae through its ability to regulate homologous recombination. Srs2 downregulates HR by stripping Rad51 from single-stranded DNA, and Srs2 is also thought to promote synthesis-dependent strand annealing by unwinding D-loops. However, it has not been possible to evaluate the relative contributions of these two distinct activities to any aspect of recombination. Here, we used a structure-based approach to design an Srs2 separation-of-function mutant that can dismantle Rad51-ssDNA filaments but is incapable of disrupting D-loops, allowing us to assess the relative contributions of these pro- and anti-recombinogenic functions. We show that this separation-of-function mutant phenocopies wild-type SRS2 in vivo, suggesting that the ability of Srs2 to remove Rad51 from ssDNA is its primary role during HR.
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Affiliation(s)
- Aviv Meir
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, 10032, USA
| | - Vivek B Raina
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, 10032, USA
| | - Carly E Rivera
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, 10032, USA
| | - Léa Marie
- Department of Microbiology & Immunology, Columbia University, New York, NY, 10032, USA
- Institute of Pharmacology and Structural Biology (IPBS), French National Centre for Scientific Research (CNRS), Université Toulouse III, Toulouse, France
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University, New York, NY, 10032, USA
- Department of Genetics & Development, Columbia University, New York, NY, 10032, USA
| | - Eric C Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, 10032, USA.
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3
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Rawal Y, Jia L, Meir A, Zhou S, Kaur H, Ruben EA, Kwon Y, Bernstein KA, Jasin M, Taylor AB, Burma S, Hromas R, Mazin AV, Zhao W, Zhou D, Wasmuth EV, Greene EC, Sung P, Olsen SK. Structural insights into BCDX2 complex function in homologous recombination. Nature 2023; 619:640-649. [PMID: 37344589 PMCID: PMC10712684 DOI: 10.1038/s41586-023-06219-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 05/15/2023] [Indexed: 06/23/2023]
Abstract
Homologous recombination (HR) fulfils a pivotal role in the repair of DNA double-strand breaks and collapsed replication forks1. HR depends on the products of several paralogues of RAD51, including the tetrameric complex of RAD51B, RAD51C, RAD51D and XRCC2 (BCDX2)2. BCDX2 functions as a mediator of nucleoprotein filament assembly by RAD51 and single-stranded DNA (ssDNA) during HR, but its mechanism remains undefined. Here we report cryogenic electron microscopy reconstructions of human BCDX2 in apo and ssDNA-bound states. The structures reveal how the amino-terminal domains of RAD51B, RAD51C and RAD51D participate in inter-subunit interactions that underpin complex formation and ssDNA-binding specificity. Single-molecule DNA curtain analysis yields insights into how BCDX2 enhances RAD51-ssDNA nucleoprotein filament assembly. Moreover, our cryogenic electron microscopy and functional analyses explain how RAD51C alterations found in patients with cancer3-6 inactivate DNA binding and the HR mediator activity of BCDX2. Our findings shed light on the role of BCDX2 in HR and provide a foundation for understanding how pathogenic alterations in BCDX2 impact genome repair.
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Affiliation(s)
- Yashpal Rawal
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Lijia Jia
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Aviv Meir
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
| | - Shuo Zhou
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Hardeep Kaur
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Eliza A Ruben
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Youngho Kwon
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Kara A Bernstein
- Department of Biochemistry & Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Alexander B Taylor
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Sandeep Burma
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Neurosurgery, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Robert Hromas
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Alexander V Mazin
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Weixing Zhao
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Daohong Zhou
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Elizabeth V Wasmuth
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, USA.
| | - Patrick Sung
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
| | - Shaun K Olsen
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
- Glenn Biggs Institute for Alzheimer's and Neurodegenerative Diseases, San Antonio, TX, USA.
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4
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Warren GM, Meir A, Wang J, Patel DJ, Greene EC, Shuman S. Structure-activity relationships at a nucleobase-stacking tryptophan required for chemomechanical coupling in the DNA resecting motor-nuclease AdnAB. Nucleic Acids Res 2021; 50:952-961. [PMID: 34967418 PMCID: PMC8789073 DOI: 10.1093/nar/gkab1270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/07/2021] [Accepted: 12/13/2021] [Indexed: 11/20/2022] Open
Abstract
Mycobacterial AdnAB is a heterodimeric helicase-nuclease that initiates homologous recombination by resecting DNA double-strand breaks. The AdnB subunit hydrolyzes ATP to drive single-nucleotide steps of 3′-to-5′ translocation of AdnAB on the tracking DNA strand via a ratchet-like mechanism. Trp325 in AdnB motif III, which intercalates into the tracking strand and makes a π stack on a nucleobase 5′ of a flipped-out nucleoside, is the putative ratchet pawl without which ATP hydrolysis is mechanically futile. Here, we report that AdnAB mutants wherein Trp325 was replaced with phenylalanine, tyrosine, histidine, leucine, or alanine retained activity in ssDNA-dependent ATP hydrolysis but displayed a gradient of effects on DSB resection. The resection velocities of Phe325 and Tyr325 mutants were 90% and 85% of the wild-type AdnAB velocity. His325 slowed resection rate to 3% of wild-type and Leu325 and Ala325 abolished DNA resection. A cryo-EM structure of the DNA-bound Ala325 mutant revealed that the AdnB motif III peptide was disordered and the erstwhile flipped out tracking strand nucleobase reverted to a continuous base-stacked arrangement with its neighbors. We conclude that π stacking of Trp325 on a DNA nucleobase triggers and stabilizes the flipped-out conformation of the neighboring nucleoside that underlies formation of a ratchet pawl.
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Affiliation(s)
- Garrett M Warren
- Molecular Biology Program, Sloan Kettering Institute, New York, NY 10065, USA
| | - Aviv Meir
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Juncheng Wang
- Structural Biology Program, Sloan Kettering Institute, New York, NY 10065, USA
| | - Dinshaw J Patel
- Structural Biology Program, Sloan Kettering Institute, New York, NY 10065, USA
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan Kettering Institute, New York, NY 10065, USA
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5
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Meir A, Greene EC. Srs2 and Pif1 as Model Systems for Understanding Sf1a and Sf1b Helicase Structure and Function. Genes (Basel) 2021; 12:1319. [PMID: 34573298 PMCID: PMC8469786 DOI: 10.3390/genes12091319] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 01/19/2023] Open
Abstract
Helicases are enzymes that convert the chemical energy stored in ATP into mechanical work, allowing them to move along and manipulate nucleic acids. The helicase superfamily 1 (Sf1) is one of the largest subgroups of helicases and they are required for a range of cellular activities across all domains of life. Sf1 helicases can be further subdivided into two classes called the Sf1a and Sf1b helicases, which move in opposite directions on nucleic acids. The results of this movement can range from the separation of strands within duplex nucleic acids to the physical remodeling or removal of nucleoprotein complexes. Here, we describe the characteristics of the Sf1a helicase Srs2 and the Sf1b helicase Pif1, both from the model organism Saccharomyces cerevisiae, focusing on the roles that they play in homologous recombination, a DNA repair pathway that is necessary for maintaining genome integrity.
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Affiliation(s)
| | - Eric C. Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA;
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6
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Abstract
Homologous recombination (HR) is important for the repair of double-stranded DNA breaks (DSBs) and stalled replication forks in all organisms. Defects in HR are closely associated with a loss of genome integrity and oncogenic transformation in human cells. HR involves coordinated actions of a complex set of proteins, many of which remain poorly understood. The key aspect of the research described here is a technology called "DNA curtains", a technique which allows for the assembly of aligned DNA molecules on the surface of a microfluidic sample chamber. They can then be visualized by total internal reflection fluorescence microscopy (TIRFM). DNA curtains was pioneered by our laboratory and allows for direct access to spatiotemporal information at millisecond time scales and nanometer scale resolution, which cannot be easily revealed through other methodologies. A major advantage of DNA curtains is that it simplifies the collection of statistically relevant data from single molecule experiments. This research continues to yield new insights into how cells regulate and preserve genome integrity.
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Affiliation(s)
- Aviv Meir
- Department of Biochemistry & Molecular Biophysics, Columbia University
| | - Muwen Kong
- Department of Biochemistry & Molecular Biophysics, Columbia University
| | - Chaoyou Xue
- Department of Biochemistry & Molecular Biophysics, Columbia University
| | - Eric C Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University;
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7
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Meir A, Lepechkin-Zilbermintz V, Kahremany S, Schwerdtfeger F, Gevorkyan-Airapetov L, Munder A, Viskind O, Gruzman A, Ruthstein S. Inhibiting the copper efflux system in microbes as a novel approach for developing antibiotics. PLoS One 2019; 14:e0227070. [PMID: 31887125 PMCID: PMC6936879 DOI: 10.1371/journal.pone.0227070] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 12/10/2019] [Indexed: 12/13/2022] Open
Abstract
Five out of six people receive at least one antibiotic prescription per year. However, the ever-expanding use of antibiotics in medicine, agriculture, and food production has accelerated the evolution of antibiotic-resistant bacteria, which, in turn, made the development of novel antibiotics based on new molecular targets a priority in medicinal chemistry. One way of possibly combatting resistant bacterial infections is by inhibiting the copper transporters in prokaryotic cells. Copper is a key element within all living cells, but it can be toxic in excess. Both eukaryotic and prokaryotic cells have developed distinct copper regulation systems to prevent its toxicity. Therefore, selectively targeting the prokaryotic copper regulation system might be an initial step in developing next-generation antibiotics. One such system is the Gram-negative bacterial CusCFBA efflux system. CusB is a key protein in this system and was previously reported to play an important role in opening the channel for efflux via significant structural changes upon copper binding while also controlling the assembly and disassembly process of the entire channel. In this study, we aimed to develop novel peptide copper channel blockers, designed by in silico calculations based on the structure of CusB. Using a combination of magnetic resonance spectroscopy and various biochemical methods, we found a lead peptide that promotes copper-induced cell toxicity. Targeting copper transport in bacteria has not yet been pursued as an antibiotic mechanism of action. Thus, our study lays the foundation for discovering novel antibiotics.
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Affiliation(s)
- Aviv Meir
- Chemistry Department, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan, Israel
| | | | - Shirin Kahremany
- Gavin Herbert Eye Institute and the Department of Ophthalmology, University of California, Irvine, California, United States of America
| | - Fabian Schwerdtfeger
- Chemistry Department, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan, Israel
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Centre for Biological Signaling Studies (BIOSS), Freiburg, Germany
| | | | - Anna Munder
- Chemistry Department, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan, Israel
| | - Olga Viskind
- Chemistry Department, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan, Israel
| | - Arie Gruzman
- Chemistry Department, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan, Israel
- * E-mail: (SR); (AG)
| | - Sharon Ruthstein
- Chemistry Department, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan, Israel
- * E-mail: (SR); (AG)
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8
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Munder A, Moskovitz Y, Meir A, Kahremany S, Levy L, Kolitz-Domb M, Cohen G, Shtriker E, Viskind O, Lellouche JP, Senderowitz H, Chessler SD, Korshin EE, Ruthstein S, Gruzman A. Neuroligin-2-derived peptide-covered polyamidoamine-based (PAMAM) dendrimers enhance pancreatic β-cells' proliferation and functions. Medchemcomm 2019; 10:280-293. [PMID: 30881615 PMCID: PMC6390468 DOI: 10.1039/c8md00419f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 12/11/2018] [Indexed: 01/02/2023]
Abstract
Pancreatic β-cell membranes and presynaptic areas of neurons contain analogous protein complexes that control the secretion of bioactive molecules. These complexes include the neuroligins (NLs) and their binding partners, the neurexins (NXs). It has been recently reported that both insulin secretion and the proliferation rates of β-cells increase when cells are co-cultured with full-length NL-2 clusters. The pharmacological use of full-length protein is always problematic due to its unfavorable pharmacokinetic properties. Thus, NL-2-derived short peptide was conjugated to the surface of polyamidoamine-based (PAMAM) dendrimers. This nanoscale composite improved β-cell functions in terms of the rate of proliferation, glucose-stimulated insulin secretion (GSIS), and functional maturation. This functionalized dendrimer also protected β-cells under cellular stress conditions. In addition, various novel peptidomimetic scaffolds of NL-2-derived peptide were designed, synthesized, and conjugated to the surface of PAMAM in order to increase the biostability of the conjugates. However, after being covered by peptidomimetics, PAMAM dendrimers were inactive. Thus, the original peptide-based PAMAM dendrimer is a leading compound for continued research that might provide a unique starting point for designing an innovative class of antidiabetic therapeutics that possess a unique mode of action.
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Affiliation(s)
- Anna Munder
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
| | - Yoni Moskovitz
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
| | - Aviv Meir
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
| | - Shirin Kahremany
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
- Department of Pharmacology , Cleveland Center for Membrane and Structural Biology , School of Medicine , Case Western Reserve University , Cleveland , OH , USA
| | - Laura Levy
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
| | - Michal Kolitz-Domb
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
| | - Guy Cohen
- Skin Research Institute , Dead Sea and Arava Research Center , Masada , Israel
| | - Efrat Shtriker
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
| | - Olga Viskind
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
| | - Jean-Paul Lellouche
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
- Nanomaterials Research Center , Institute of Nanotechnology & Advanced Materials (BINA) , Bar-Ilan University , Ramat-Gan , Israel
| | - Hanoch Senderowitz
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
| | - Steven D Chessler
- Division of Endocrinology, Diabetes & Metabolism , Department of Medicine , University of California , Irvine , CA , USA
| | - Edward E Korshin
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
| | - Sharon Ruthstein
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
| | - Arie Gruzman
- Department of Chemistry , Faculty of Exact Sciences , Bar-Ilan University , Ramat-Gan , Israel . ;
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9
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Abstract
Bacterial cells have developed sophisticated systems to deal with the toxicity of metal ions. Escherichia coli CusCFBA is a complex efflux system, responsible for transferring Cu(I) and Ag(I) ions; this system, located in the periplasm, involves four proteins, CusA, CusB, CusC, and CusF. CusA, CusB, and CusC are connected to one another in an oligomerization ratio of 3:6:3 CusA/CusB/CusC to form the CusCBA periplasm membrane transporter. CusB is an adaptor protein that connects the two membrane proteins CusA (inner membrane) and CusC (outer membrane). CusF is a metallochaperone that transfers Cu(I) and Ag(I) to the CusCBA transporter from the periplasm. The crystal structures of CusB, CusC, CusF, and the CusBA complex have been resolved, shedding some light on the efflux mechanism underlying this intriguing system. However, since CusB is an adaptor protein, its role in operating this system is significant, and should be understood in detail. Here, we utilize EPR spectroscopy to target the conformational changes that take place in the full CusB protein upon binding Cu(I). We reveal that CusB is a dimer in solution, and that the orientation of one molecule with respect to the other molecule changes upon Cu(I) coordination, resulting in a more compact CusB structure. These structural and topological changes upon Cu(I) binding probably play the role of a switch for opening the channel and transferring metal ions from CusB to CusC and out of the cell.
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Affiliation(s)
- Aviv Meir
- Department of Chemistry, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan, Israel
| | - Ahmad Abdelhai
- Department of Chemistry, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan, Israel
| | - Yoni Moskovitz
- Department of Chemistry, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan, Israel
| | - Sharon Ruthstein
- Department of Chemistry, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan, Israel.
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10
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Shilina Y, Ziv B, Meir A, Banerjee A, Ruthstein S, Luski S, Aurbach D, Halalay IC. Combined Electron Paramagnetic Resonance and Atomic Absorption Spectroscopy/Inductively Coupled Plasma Analysis As Diagnostics for Soluble Manganese Species from Mn-Based Positive Electrode Materials in Li-ion Cells. Anal Chem 2016; 88:4440-7. [DOI: 10.1021/acs.analchem.6b00204] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yuliya Shilina
- Department
of Chemistry, Bar-Ilan University, Ramat-Gan 590002, Israel
| | - Baruch Ziv
- Department
of Chemistry, Bar-Ilan University, Ramat-Gan 590002, Israel
| | - Aviv Meir
- Department
of Chemistry, Bar-Ilan University, Ramat-Gan 590002, Israel
| | - Anjan Banerjee
- Department
of Chemistry, Bar-Ilan University, Ramat-Gan 590002, Israel
| | - Sharon Ruthstein
- Department
of Chemistry, Bar-Ilan University, Ramat-Gan 590002, Israel
| | - Shalom Luski
- Department
of Chemistry, Bar-Ilan University, Ramat-Gan 590002, Israel
| | - Doron Aurbach
- Department
of Chemistry, Bar-Ilan University, Ramat-Gan 590002, Israel
| | - Ion C. Halalay
- General Motors Global Research & Development Center, Warren, Michigan 58092-2031, United States
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11
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Weintraub S, Moskovitz Y, Fleker O, Levy AR, Meir A, Ruthstein S, Benisvy L, Gruzman A. SOD mimetic activity and antiproliferative properties of a novel tetra nuclear copper (II) complex. J Biol Inorg Chem 2015; 20:1287-98. [PMID: 26547749 DOI: 10.1007/s00775-015-1307-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/21/2015] [Indexed: 01/22/2023]
Abstract
The search for novel anticancer therapeutic agents is an urgent and important issue in medicinal chemistry. Here, we report on the biological activity of the copper-based bioinorganic complex Cu4 (2,4-di-tert-butyl-6-(1H-imidazo- [1, 10] phenanthrolin-2-yl)phenol)4]·10 CH3CN (2), which was tested in rat L6 myotubes, mouse NSC-34 motor neurone-like cells, and HepG-2 human liver carcinoma. Upon 96 h incubation, 2 exhibited a significant cytotoxic effect on all three types of cells via activation of two cell death mechanisms (apoptosis and necrosis). Complex 2 exhibited better potency and efficacy than the canonical cytotoxic drug cisplatin. Moreover, during shorter incubations, complex 2 demonstrated a significant SOD mimetic activity, and it was more effective and more potent than the well-known SOD mimetic TEMPOL. In addition, complex 2 was able to interact with DNA and, cleave DNA in the presence of sodium ascorbate. This study shows the potential of using polynuclear redox active compounds for developing novel anticancer drugs through SOD-mimetic redox pathways.
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Affiliation(s)
- Sagiv Weintraub
- Department of Chemistry, Bar-Ilan University, 5290002, Ramat Gan, Israel
| | - Yoni Moskovitz
- Department of Chemistry, Bar-Ilan University, 5290002, Ramat Gan, Israel
| | - Ohad Fleker
- Department of Chemistry, Bar-Ilan University, 5290002, Ramat Gan, Israel
| | - Ariel R Levy
- Department of Chemistry, Bar-Ilan University, 5290002, Ramat Gan, Israel
| | - Aviv Meir
- Department of Chemistry, Bar-Ilan University, 5290002, Ramat Gan, Israel
| | - Sharon Ruthstein
- Department of Chemistry, Bar-Ilan University, 5290002, Ramat Gan, Israel
| | - Laurent Benisvy
- Department of Chemistry, Bar-Ilan University, 5290002, Ramat Gan, Israel.
| | - Arie Gruzman
- Department of Chemistry, Bar-Ilan University, 5290002, Ramat Gan, Israel.
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12
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Meir A, Natan A, Moskovitz Y, Ruthstein S. EPR spectroscopy identifies Met and Lys residues that are essential for the interaction between the CusB N-terminal domain and metallochaperone CusF. Metallomics 2015; 7:1163-72. [PMID: 25940871 DOI: 10.1039/c5mt00053j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Copper plays a key role in all living organisms by serving as a cofactor for a large variety of proteins and enzymes involved in electron transfer, oxidase and oxygenase activities, and the detoxification of oxygen radicals. Due to its toxicity, a conserved homeostasis mechanism is required. In E. coli, the CusCFBA efflux system is a copper-regulating system and is responsible for transferring Cu(I) and Ag(I) out of the periplasm domain into the extracellular domain. Two of the components of this efflux system, the CusF metallochaperone and the N-terminal domain of CusB, have been thought to play significant roles in the function of this efflux system. Resolving the metal ion transport mechanism through this efflux system is vital for understanding metal- and multidrug-resistant microorganisms. This work explores one aspect of the E. coli resistance mechanism by observing the interaction between the N-terminal domain of CusB and the CusF protein, using electron paramagnetic resonance (EPR) spectroscopy, circular dichroism (CD), and chemical cross-linking. The data summarized here show that M36 and M38 of CusB are important residues for both the Cu(I) coordination to the CusB N-terminal domain and the interaction with CusF, and K32 is essential for the interaction with CusF. In contrast, the K29 residue is less consequential for the interaction with CusF, whereas M21 is mostly important for the proper interaction with CusF.
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Affiliation(s)
- Aviv Meir
- Department of Chemistry, Faculty of Exact Science, Bar Ilan University, Ramat Gan, 5290002, Israel.
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13
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Sarig G, Meir A, Wollner M, Brenner B, Haim N. Soluble endothelial protein C receptor and coagulation parameters as prognostic factors in non-small cell lung carcinoma. J Thromb Haemost 2013; 11:768-71. [PMID: 23323811 DOI: 10.1111/jth.12134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 01/09/2013] [Indexed: 11/29/2022]
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14
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Sarig G, Meir A, Wollner M, Shafat I, Brenner B, Haim N. Soluble endothelial protein C receptor (sEPCR) and coagulation parameters as prognostic factors in advanced non small cell lung cancer (NSCLC). Thromb Res 2012. [DOI: 10.1016/s0049-3848(12)70084-1] [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: 11/29/2022]
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15
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Harel-Beja R, Tzuri G, Portnoy V, Lotan-Pompan M, Lev S, Cohen S, Dai N, Yeselson L, Meir A, Libhaber SE, Avisar E, Melame T, van Koert P, Verbakel H, Hofstede R, Volpin H, Oliver M, Fougedoire A, Stalh C, Fauve J, Copes B, Fei Z, Giovannoni J, Ori N, Lewinsohn E, Sherman A, Burger J, Tadmor Y, Schaffer AA, Katzir N. A genetic map of melon highly enriched with fruit quality QTLs and EST markers, including sugar and carotenoid metabolism genes. Theor Appl Genet 2010; 121:511-33. [PMID: 20401460 DOI: 10.1007/s00122-010-1327-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 03/22/2010] [Indexed: 05/03/2023]
Abstract
A genetic map of melon enriched for fruit traits was constructed, using a recombinant inbred (RI) population developed from a cross between representatives of the two subspecies of Cucumis melo L.: PI 414723 (subspecies agrestis) and 'Dulce' (subspecies melo). Phenotyping of 99 RI lines was conducted over three seasons in two locations in Israel and the US. The map includes 668 DNA markers (386 SSRs, 76 SNPs, six INDELs and 200 AFLPs), of which 160 were newly developed from fruit ESTs. These ESTs include candidate genes encoding for enzymes of sugar and carotenoid metabolic pathways that were cloned from melon cDNA or identified through mining of the International Cucurbit Genomics Initiative database (http://www.icugi.org/). The map covers 1,222 cM with an average of 2.672 cM between markers. In addition, a skeleton physical map was initiated and 29 melon BACs harboring fruit ESTs were localized to the 12 linkage groups of the map. Altogether, 44 fruit QTLs were identified: 25 confirming QTLs described using other populations and 19 newly described QTLs. The map includes QTLs for fruit sugar content, particularly sucrose, the major sugar affecting sweetness in melon fruit. Six QTLs interacting in an additive manner account for nearly all the difference in sugar content between the two genotypes. Three QTLs for fruit flesh color and carotenoid content were identified. Interestingly, no clear colocalization of QTLs for either sugar or carotenoid content was observed with over 40 genes encoding for enzymes involved in their metabolism. The RI population described here provides a useful resource for further genomics and metabolomics studies in melon, as well as useful markers for breeding for fruit quality.
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Affiliation(s)
- R Harel-Beja
- Department of Vegetable Research, Agricultural Research Organization, Newe Ya'ar Research Center, P.O. Box 1021, Ramat Yishay, 30095, Israel
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16
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Meir A, McNally DS, Fairbank JC, Jones D, Urban JP. The internal pressure and stress environment of the scoliotic intervertebral disc — a review. Proc Inst Mech Eng H 2008; 222:209-19. [DOI: 10.1243/09544119jeim303] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The aetiology, in terms of both initiation and progression, of the deformity in idiopathic scoliosis is at present unclear. Even in neuromuscular cases, the mechanisms underlying progression are not fully elucidated. It is thought, however, that asymmetrical loading is involved in the progression of the disease, with evidence mainly from animal studies and modelling. There is, however, very little direct information as to the origin or mechanism of action of these forces in the scoliotic spine. This review describes the concept of intervertebral disc pressure or stress and examines possible measurement techniques. The biological and mechanical consequences of abnormalities in these parameters are described. Future possible studies and their clinical significance are also briefly discussed.Techniques of pressure measurement have culminated in the development of ‘pressure profilometry’, which provides stress profiles across the disc in mutually perpendicular axes. A hydrated intervertebral disc exhibits mainly hydrostatic behaviour. However, in pathological states such as degeneration and scoliosis, non-hydrostatic behaviour predominates and annular peaks of stress occur. Recent studies have shown that, in scoliosis, high hydrostatic pressures are seen with asymmetrical stresses from concave to convex sides. These abnormalities could influence both disc and endplate cellular activity directly, causing asymmetrical growth and matrix changes. In addition, disc cells could be influenced via nutritional changes consequent to end-plate calcification.Evidence suggests that the stress environment of the scoliotic disc is abnormal, probably generated by high and asymmetrical loading of non-muscular origin. If present in the scoliotic spine during daily activities, this could generate a positive feedback of cellular changes, resulting in curve progression. Future advances in understanding may rely on the development of computer models owing to the difficulties of in-vivo invasive measurements.
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Affiliation(s)
- A Meir
- Nuffield Department of Orthopaedic Surgery, Oxford, UK
| | - D S McNally
- Physiology Laboratory, Oxford University, Oxford, UK
| | - J C Fairbank
- Nuffield Department of Orthopaedic Surgery, Oxford, UK
| | - D Jones
- Nuffield Department of Orthopaedic Surgery, Oxford, UK
| | - J P Urban
- Institute of Biomechanics, University of Nottingham, Nottingham, UK
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17
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Machavariani G, Jackel S, Lumer Y, Moshe I, Meir A. Spatially variable retardation plate for beam brightness enhancement in a high-power laser. Opt Lett 2007; 32:2626-8. [PMID: 17767327 DOI: 10.1364/ol.32.002626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
We present a simple and robust method for brightness enhancement, efficiently transforming a radially polarized LG (0,1)(*) mode into a nearly Gaussian beam of much higher quality. We use for this a spatially variable retardation plate and a spatial filter. The analysis shows that the transformation yields an increase in brightness by a factor of 3.4. In the experiment, we transformed a high-power Nd:YAG radially polarized (0,1)(*) LG beam with power of 70 W and M(2)=2.6 into a nearly Gaussian beam with M(2)=1.36. This resulted in brightness enhancement by a factor of 2.6.
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Affiliation(s)
- G Machavariani
- Soreq Nuclear Research Center, Electro-Optics Division, Yavne 81800, Israel.
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18
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Abstract
Lateral insufficiency fractures following total hip replacement have been reported with the femoral stems positioned in varus, together with osteopenia of the lateral femoral cortex. Any abnormal alignment of the lower limbs, such as genu valgum, will alter the load distribution across the femoral cortices, and repetitive loading during walking will predispose the bones to stress fractures at any stress riser point, such as the tip of a femoral component. Bilateral femoral stress fractures post total hip replacements have not been previously described. We present a 55-year-old woman, diagnosed with juvenile idiopathic arthritis, who had undergone bilateral total hip replacements and bilateral knee replacements. The knees 15 years postoperatively were in valgus and the left knee was extremely stiff, flexing to just 5. The patient presented with bilateral thigh pain, with plain radiographs confirming bilateral periprosthetic fractures of the femur at the tip of well-fixed femoral components. There was no history of injury and her hips were functioning well up to this time. The patient required revision of both hips to long-stem uncemented components, bypassing the fractures, and revision of both knees to stemmed semi-constrained implants, thereby correcting the alignment of both lower limbs. Both fractures healed and the patient is currently pain-free and mobile with walking aids. Surgeons must remain aware that when implants are in situ, abnormal alignments will lead to abnormal forces, and stress fractures are likely to occur at any stress riser around the implant. Avoiding malalignment will avoid this complication.
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Affiliation(s)
- H Al-Khateeb
- Trauma and Orthopaedic Department, Heatherwood and Wexham Park Hospitals, Slough, UK.
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19
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Machavariani G, Lumer Y, Moshe I, Meir A, Jackel S. Efficient extracavity generation of radially and azimuthally polarized beams. Opt Lett 2007; 32:1468-70. [PMID: 17546157 DOI: 10.1364/ol.32.001468] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We demonstrate an efficient transformation of a linearly polarized Gaussian beam to a radially or an azimuthally polarized doughnut (0,1)* Laguerre-Gaussian beam of high purity. We use a spatially variable retardation plate, composed of eight sectors of a lambda/2 retardation plate, to transform a linear polarization distribution to radial/azimuthal distribution. We transformed an Nd:YAG Gaussian beam with M(2)=1.3 to a radially and azimuthally polarized (0,1)* Laguerre-Gaussian beams with M(2)=2.5 and degree of radial/azimuthal polarization of 96-98%.
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Affiliation(s)
- G Machavariani
- SoreqNuclear Research Center, Electro-Optics Division, Yavne 81800, Israel.
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20
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Sarig G, Meir A, Wollner M, Brenner B, Haim N. PO-67 Hypercoagulable parameters as predictors of prognosis in patients with advanced non-small cell lung carcinoma. Thromb Res 2007. [DOI: 10.1016/s0049-3848(07)70220-7] [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: 11/15/2022]
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21
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Nasser AM, Paulman H, Sela O, Ktaitzer T, Cikurel H, Zuckerman I, Meir A, Aharoni A, Adin A. UV disinfection of wastewater effluents for unrestricted irrigation. Water Sci Technol 2006; 54:83-8. [PMID: 17037137 DOI: 10.2166/wst.2006.452] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Wastewater reuse in arid regions is important for the production of a water resource to be utilised for non-potable purposes and to prevent the environmental transmission of disease-causing agents. This study was conducted to evaluate the effect of water quality on the comparative disinfection efficiency of viruses, bacteria and spores by UV irradiation. Furthermore, the microbial quality of effluent produced by coagulation, high rate filtration (HRF) and either UV irradiation or chlorination was determined. Using low pressure collimated beam, a UV dose of 80 mWs/cm2 was needed to achieve a 3-log10 inactivation of either rotavirus SA-11 or coliphage MS2, whereas over 5-log10 inactivation of E. coli was reached with a dose of only 20 mWs/cm2. B. subtilis inactivation was found to be linear up to a dose of 40 mWs/cm2 and then a tailing up to a UV dose of 120 mWs/cm2 was observed. It is worth noting that effluent turbidity of < 5 NTU did not influence the inactivation efficiency of UV irradiation. Operation of a pilot plant to treat secondary effluent by coagulation, HRF and UV disinfection at a UV dose of 80 mWs/cm2 resulted in the production of high quality effluent in compliance with the Israel standards for unrestricted irrigation (< 10 CFU/100 mL faecal coliform and turbidity of < 5 NTU). Sulphite reducing clostridia (SRC) were found to be more resistant than coliphages and F coliform for UV irradiation. The results of this study indicated that UV disinfection is suitable for the production of effluents for unrestricted irrigation of food crops.
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Affiliation(s)
- A M Nasser
- Water Quality Research Laboratory, Ministry of Health, Israel.
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22
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Raghib A, Bertaso F, Davies A, Page KM, Meir A, Bogdanov Y, Dolphin AC. Dominant-negative synthesis suppression of voltage-gated calcium channel Cav2.2 induced by truncated constructs. J Neurosci 2001; 21:8495-504. [PMID: 11606638 PMCID: PMC6762802] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2001] [Revised: 08/15/2001] [Accepted: 08/23/2001] [Indexed: 02/21/2023] Open
Abstract
Voltage-gated calcium channel alpha1 subunits consist of four domains (I-IV), each with six transmembrane segments. A number of truncated isoforms have been identified to occur as a result of alternative splicing or mutation. We have examined the functional consequences for expression of full-length Ca(v)2.2 (alpha1B) of its coexpression with truncated constructs of Ca(v)2.2. Domains I-II or domains III-IV, when expressed individually, together with the accessory subunits beta1b and alpha2delta-1, did not form functional channels. When they were coexpressed, low-density whole-cell currents and functional channels with properties similar to wild-type channels were observed. However, when domain I-II, domain III-IV, or domain I alone were coexpressed with full-length Ca(v)2.2, they markedly suppressed its functional expression, although at the single channel level, when channels were recorded, there were no differences in their biophysical properties. Furthermore, when it was coexpressed with either domain I-II or domain I, the fluorescence of green fluorescent protein (GFP)-Ca(v)2.2 and expression of Ca(v)2.2 protein was almost abolished. Suppression does not involve sequestration of the Ca(v)beta subunit, because loss of GFP-Ca(v)2.2 expression also occurred in the absence of beta subunit, and the effect of domain I-II or domain I could not be mimicked by the cytoplasmic I-II loop of Ca(v)2.2. It requires transmembrane segments, because the isolated Ca(v)2.2 N terminus did not have any effect. Our results indicate that the mechanism of suppression of Ca(v)2.2 by truncated constructs containing domain I involves inhibition of channel synthesis, which may represent a role of endogenously expressed truncated Ca(v) isoforms.
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Affiliation(s)
- A Raghib
- Department of Pharmacology, University College London, London WC1E6BT, United Kingdom
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23
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Barclay J, Balaguero N, Mione M, Ackerman SL, Letts VA, Brodbeck J, Canti C, Meir A, Page KM, Kusumi K, Perez-Reyes E, Lander ES, Frankel WN, Gardiner RM, Dolphin AC, Rees M. Ducky mouse phenotype of epilepsy and ataxia is associated with mutations in the Cacna2d2 gene and decreased calcium channel current in cerebellar Purkinje cells. J Neurosci 2001; 21:6095-104. [PMID: 11487633 PMCID: PMC6763162] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2001] [Revised: 05/10/2001] [Accepted: 06/01/2001] [Indexed: 02/21/2023] Open
Abstract
The mouse mutant ducky, a model for absence epilepsy, is characterized by spike-wave seizures and ataxia. The ducky gene was mapped previously to distal mouse chromosome 9. High-resolution genetic and physical mapping has resulted in the identification of the Cacna2d2 gene encoding the alpha2delta2 voltage-dependent calcium channel subunit. Mutations in Cacna2d2 were found to underlie the ducky phenotype in the original ducky (du) strain and in a newly identified strain (du(2J)). Both mutations are predicted to result in loss of the full-length alpha2delta2 protein. Functional analysis shows that the alpha2delta2 subunit increases the maximum conductance of the alpha1A/beta4 channel combination when coexpressed in vitro in Xenopus oocytes. The Ca(2+) channel current in acutely dissociated du/du cerebellar Purkinje cells was reduced, with no change in single-channel conductance. In contrast, no effect on Ca(2+) channel current was seen in cerebellar granule cells, results consistent with the high level of expression of the Cacna2d2 gene in Purkinje, but not granule, neurons. Our observations document the first mammalian alpha2delta mutation and complete the association of each of the major classes of voltage-dependent Ca(2+) channel subunits with a phenotype of ataxia and epilepsy in the mouse.
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Affiliation(s)
- J Barclay
- Department of Paediatrics and Child Health, Royal Free and University College Medical School, The Rayne Institute, London, WC1E 6JJ, United Kingdom
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24
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Groisman GM, Sabo E, Meir A, Polak-Charcon S. Enterocyte apoptosis and proliferation are increased in microvillous inclusion disease (familial microvillous atrophy). Hum Pathol 2000; 31:1404-10. [PMID: 11112216] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Microvillous inclusion disease (MID) is characterized by diffuse villous atrophy without inflammatory changes. While increased apoptosis has been related to mucosal flattening in celiac disease, the role of apoptosis in the pathogenesis of MID is unknown. The aim of this study was to assess the rates of apoptosis and cell proliferation in MID and to compare them with those of normal controls and celiac disease. Small intestinal biopsies from 5 infants with MID, 10 children with normal villous architecture, and 10 children with untreated celiac disease were stained with the terminal uridine deoxynucleotidyl nick end labeling (TUNEL) method to assess apoptotic activity, and with Ki-67 immunohistochemistry to assess cellular proliferation. TUNEL and Ki-67 positive enterocytes were counted in a minimum of 20 well oriented half crypts per section. The percentage of apoptotic cells per crypt (apoptotic index) in normal, MID, and celiac biopsies was 0.03 +/- 0.01%, 0.08 +/- 0.08%, and 0.16 +/- 0.3%, respectively. Significant differences were found between normal and MID, and between normal and celiac cases. The percentage of Ki-67 positive cells per crypt (proliferation index) in normal, MID, and celiac cases was 14 +/- 2.5%, 28 +/- 9.2%, and 56 +/- 14%. Significant differences were found between the 3 groups. In conclusion, (1) enterocyte apoptosis and proliferation are increased in MID; (2) apoptosis appears to be an important factor of cell loss and may be, at least in part, responsible for villous atrophy in MID; and (3) crypts in MID are hyperplastic and not hypoplastic. HUM PATHOL 31:1404-1410.
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25
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Abstract
Voltage-dependent calcium channels (VDCCs) are heteromultimers composed of a pore-forming alpha1 subunit and auxiliary subunits, including the intracellular beta subunit, which has a strong influence on the channel properties. Voltage-dependent inhibitory modulation of neuronal VDCCs occurs primarily by activation of G-proteins and elevation of the free G beta gamma dimer concentration. Here we have examined the interaction between the regulation of N-type (alpha 1 B) channels by their beta subunits and by G beta gamma dimers, heterologously expressed in COS-7 cells. In contrast to previous studies suggesting antagonism of G protein inhibition by the VDCC beta subunit, we found a significantly larger G beta gamma-dependent inhibition of alpha 1 B channel activation when the VDCC alpha 1 B and beta subunits were coexpressed. In the absence of coexpressed VDCC beta subunit, the G beta gamma dimers, either expressed tonically or elevated via receptor activation, did not produce the expected features of voltage-dependent G protein modulation of N-type channels, including slowed activation and prepulse facilitation, while VDCC beta subunit coexpression restored all of the hallmarks of G beta gamma modulation. These results suggest that the VDCC beta subunit must be present for G beta gamma to induce voltage-dependent modulation of N-type calcium channels.
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Affiliation(s)
- A Meir
- Department of Pharmacology, University College London, London WC1E 6BT, United Kingdom.
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26
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Meir A, Ginsburg S, Butkevich A, Kachalsky SG, Kaiserman I, Ahdut R, Demirgoren S, Rahamimoff R. Ion channels in presynaptic nerve terminals and control of transmitter release. Physiol Rev 1999; 79:1019-88. [PMID: 10390521 DOI: 10.1152/physrev.1999.79.3.1019] [Citation(s) in RCA: 220] [Impact Index Per Article: 8.8] [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: 11/22/2022] Open
Abstract
The primary function of the presynaptic nerve terminal is to release transmitter quanta and thus activate the postsynaptic target cell. In almost every step leading to the release of transmitter quanta, there is a substantial involvement of ion channels. In this review, the multitude of ion channels in the presynaptic terminal are surveyed. There are at least 12 different major categories of ion channels representing several tens of different ion channel types; the number of different ion channel molecules at presynaptic nerve terminals is many hundreds. We describe the different ion channel molecules at the surface membrane and inside the nerve terminal in the context of their possible role in the process of transmitter release. Frequently, a number of different ion channel molecules, with the same basic function, are present at the same nerve terminal. This is especially evident in the cases of calcium channels and potassium channels. This abundance of ion channels allows for a physiological and pharmacological fine tuning of the process of transmitter release and thus of synaptic transmission.
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Affiliation(s)
- A Meir
- Department of Physiology and the Bernard Katz Minerva Centre for Cell Biophysics, Hebrew University Hadassah Medical School, Jerusalem, Israel
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27
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Abstract
The bicuspid (mitral) valve complex of the human heart consists of functional units which include the valve leaflets, chordae tendineae and the papillary muscles. The mechanical properties of these functional units depend to a large extent on the link between the muscle and the valve. This link is usually arranged in a branching network of avascular tendinous chordae composed of collagen and elastic fibres, which transmit contractions of the papillary muscle to the valve leaflets. In order to perform their function efficiently, the chordae have to possess a high degree of elasticity, as well as considerable strength and endurance. Human chordae tendineae originating from the left ventricles were obtained from 7 embalmed cadavers and 6 postmortem subjects of various ages. Samples washed in saline were fixed or postfixed in 9 % formol saline. Observations were made by illuminating the chordae along their axes. The reflected images originating from the superficial collagenous layers of the relaxed chordae showed a striped pattern 11 microm in width. Scanning electron and light microscopy of the chordae confirmed an undulating pattern of collagen fibrils arranged in bundles of planar waves in register and around the entire circumference of the chorda. The dimensions of the waves correlated with those of the striped reflected pattern. The observed undulating arrangement of the collagen fibrils appears to produce an inherent built-in elasticity which is likely to be of considerable advantage for a tissue which is under continuous repetitive stress. The chordae were covered by endocardium composed of a superficial layer of smooth squamous endothelial cells and an underlying dense layer of elastic fibres. It is suggested that the relaxed striped chordae, consisting of undulating collagen fibrils, straighten when the chordae become stretched by papillary muscle contraction, thereby mitigating the peak stress developed during muscle contraction. On relaxation the elastic tissue tends to return the collagen to its wavy configuration. It is also suggested that the regular wavy pattern of collagen seen in young individuals gradually changes with age by elongation of the wave pattern which eventually becomes randomised. In addition, with increasing age, substantial cushions of connective tissue appear below endocardium while the dense collagenous core has a reduced cross-sectional area which may lead to stretching and eventual rupture of the chordae.
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Affiliation(s)
- C Millington-Sanders
- Division of Biomedical Sciences, Imperial College School of Medicine at St. Mary's Hospital, London, UK
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28
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Abstract
Native T-type voltage-dependent calcium channels are low voltage-activated and have a small single channel conductance of 5-8 pS, which distinguishes them from any known cloned calcium channels whose conductances are 12-25 pS. Here, we show that when alpha1B, alpha1E, or alpha1C are expressed in COS7 cells, which contain no endogenous calcium channel subunits or calcium channels, they each exhibit a 4-7 pS channel as well as a large conductance channel. At low depolarizations, or when the alpha1 subunit is expressed in the absence of auxiliary alpha2-delta or beta subunits, the small conductance channels are seen alone, and their biophysical properties, including voltage dependence and kinetics of activation and inactivation, are very similar to native T-type calcium channels.
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Affiliation(s)
- A Meir
- Department of Pharmacology, University College London, United Kingdom
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29
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Abstract
The bursting K+ channel is the most common channel in fused Torpedo presynaptic nerve terminals. It possesses the property of 'statistical memory', demonstrated by non-random probability of channel opening. We examined the voltage dependence of the statistical memory and report that removal of channel inactivation by hyperpolarization abolishes it. Addition of the potassium channel blocker 4-aminopyridine to the bath solution led to disappearance of statistical memory, while raising extracellular potassium concentration had the opposite effect. Another common channel at Torpedo nerve terminals which is a non-selective channel did not exhibit statistical memory. We conclude that statistical memory is a channel-specific phenomenon and speculate regarding its possible role in cellular and network properties of the nervous system.
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Affiliation(s)
- A Butkevich
- Department of Physiology, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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30
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Abstract
1. We used a preparation of fused presynaptic nerve terminals of Torpedo electromotor nerve and the patch-clamp technique for characterization of single ion channels. We report here of a large, nonselective ion channel which is highly voltage dependent. 2. The slope conductance of the I-V relation was estimated by either direct measurement of the single-channel current amplitude at different voltages (850 +/- 18 pS (SE); n = 9) or by variance analysis (834 +/- 23 pS; n = 5). 3. The voltage dependence was examined in three ways. At steady-state DC voltage conditions, NPo (the open probability times the number of channels in the patch) was estimated. At potentials < 0 mV, the probability of the channel to open is negligible and increases dramatically, within a very narrow voltage range, to > 50% at +8 mV (n = 8). 4. In pulse experiments, the activation time delay is shorter as the voltage step reaches more positive values. The mean time for half activation (T1/2) decreases from 15 ms at +10 mV to 4 ms at +30 mV (n = 5). 5. Ensemble currents exhibit rectification in response to voltage ramps at negative potentials (n = 10). 6. The channel was found to be nonselective. Its permeability to Na+, K+, Cl-, glutamate, Ba+2, and Ca+2, relative to Na+, was 1.00, 1.00, 1.22, 1.07, 0.85, and 0.62, respectively. 7. Based on the transport number of calcium, the calculated driving force, and the mean channel open time, we estimated the number of calcium ions entering the nerve terminal upon depolarization. This number is not substantially different from the number of ions entering through voltage-dependent, calcium-selective channels in other cells. 8. We speculate that this nonselective ion channel, may serve as a calcium entry route into the nerve terminal and hence be involved in transmitter release.
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Affiliation(s)
- A Meir
- Department of Physiology, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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Meir A, Edry-Schiller J, Habartova A, Mahinson H, Rahamimoff R. Currents and channels in the presynaptic nerve terminal. Isr J Med Sci 1993; 29:517-29. [PMID: 7693613] [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: 01/26/2023]
Abstract
Synaptic transmission is a key element in neuronal communication in the nervous system. It is determined by two basic sets of processes: release of transmitter from the presynaptic nerve ending and the detection and response by the postsynaptic cell. The release of transmitter is crucially dependent on the interplay among the ion channels in the surface membrane of the presynaptic terminal. In this article we describe the methods used in the study of the ion channels in secretory nerve endings and present the 16 calcium, sodium, chloride, cationic and potassium ion channels discovered in various preparations. We speculate about the physiological and pathophysiological roles of some of these ion channels.
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Affiliation(s)
- A Meir
- Department of Physiology, Bernard Katz Minerva Center on Cell Biophysics, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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Abstract
We interviewed 120 Bedouin men to elicit their views about the traditional Bedouin support system for the elderly (a collective family fund) and the more recent welfare support allowances that all Israeli elders are entitled to. Desire to maintain or return to the traditional system varied with the respondent's place on a continuum of seminomadism to rural sedentarization to semiurbanization. Differences were also found between the real Bedouin and the fellahim Bedouin respondents.
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Affiliation(s)
- A Meir
- Department of Geography, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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Abstract
The authors analyze trends in child mortality among the Bedouin in Israel, who are in the process of changing from a nomadic to a sedentary way of life. "At early stages of sedentarization and development, child mortality rates decline, as expected, then rise, only to decline again. The positive relationship that is theoretically assumed to exist in general between declining child mortality and socio-economic development over time and space may thus possibly be refined, to accompany an earlier similar refinement regarding fertility decline. Demographic indicators may consequently respond late to development processes."
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Abstract
"This paper attempts to gather and present as much information as possible on crude birth and death rates and natural increase rates for various pastoral nomadic societies in different African and Middle Eastern countries. The information is arranged by a subdivision into nomads, seminomads, and sedentarized nomads. A summarization of this information suggests a possible pattern by which birth rates rise, death rates fall (but may rise in certain circumstances), and natural increase rates rise along the nomadism-sedentarism continuum. Such a possible pattern has several policy implications for governments assessing the needs of a nomadic society undergoing a process of change in its socio-ecological relationships."
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Meir A. Demographic transition theory: a neglected aspect of the nomadism-sedentarism continuum. Trans Inst Br Geogr 1986; 11:199-211. [PMID: 12314312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Affiliation(s)
- A. Meir
- University of Alberta, Edmonton, Alberta
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- University of Alberta, Edmonton, Alberta
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