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Yu J, Jackson NE, Xu X, Morgenstern Y, Kaufman Y, Ruths M, de Pablo JJ, Tirrell M. Multivalent counterions diminish the lubricity of polyelectrolyte brushes. Science 2018; 360:1434-1438. [PMID: 29954973 DOI: 10.1126/science.aar5877] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 05/08/2018] [Indexed: 01/06/2023]
Abstract
Polyelectrolyte brushes provide wear protection and lubrication in many technical, medical, physiological, and biological applications. Wear resistance and low friction are attributed to counterion osmotic pressure and the hydration layer surrounding the charged polymer segments. However, the presence of multivalent counterions in solution can strongly affect the interchain interactions and structural properties of brush layers. We evaluated the lubrication properties of polystyrene sulfonate brush layers sliding against each other in aqueous solutions containing increasing concentrations of counterions. The presence of multivalent ions (Y3+, Ca2+, Ba2+), even at minute concentrations, markedly increases the friction forces between brush layers owing to electrostatic bridging and brush collapse. Our results suggest that the lubricating properties of polyelectrolyte brushes in multivalent solution are hindered relative to those in monovalent solution.
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Affiliation(s)
- J Yu
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.,Institute for Molecular Engineering, Argonne National Laboratory, Lemont, IL 60439, USA.,School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798
| | - N E Jackson
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.,Institute for Molecular Engineering, Argonne National Laboratory, Lemont, IL 60439, USA
| | - X Xu
- Department of Chemistry, University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - Y Morgenstern
- Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Y Kaufman
- Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - M Ruths
- Department of Chemistry, University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - J J de Pablo
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA. .,Institute for Molecular Engineering, Argonne National Laboratory, Lemont, IL 60439, USA
| | - M Tirrell
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA. .,Institute for Molecular Engineering, Argonne National Laboratory, Lemont, IL 60439, USA
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Khan A, Yadav NS, Morgenstern Y, Zemach A, Grafi G. Activation of Tag1 transposable elements in Arabidopsis dedifferentiating cells and their regulation by CHROMOMETHYLASE 3-mediated CHG methylation. Biochim Biophys Acta 2016; 1859:1289-98. [PMID: 27475038 DOI: 10.1016/j.bbagrm.2016.07.012] [Citation(s) in RCA: 7] [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] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Revised: 07/13/2016] [Accepted: 07/25/2016] [Indexed: 12/11/2022]
Abstract
Dedifferentiation, that is, the acquisition of stem cell-like state, commonly induced by stress (e.g., protoplasting), is characterized by open chromatin conformation, a chromatin state that could lead to activation of transposable elements (TEs). Here, we studied the activation of the Arabidopsis class II TE Tag1, in which two copies, situated close to each other (near genes) on chromosome 1 are found in Landsberg erecta (Ler) but not in Columbia (Col). We first transformed protoplasts with a construct in which a truncated Tag1 (ΔTag1 non-autonomous) blocks the expression of a reporter gene AtMBD5-GFP and found a relatively high ectopic excision of ΔTag1 accompanied by expression of AtMBD5-GFP in protoplasts derived from Ler compared to Col; further increase was observed in ddm1 (decrease in DNA methylation1) protoplasts (Ler background). Ectopic excision was associated with transcription of the endogenous Tag1 and changes in histone H3 methylation at the promoter region. Focusing on the endogenous Tag1 elements we found low level of excision in Ler protoplasts, which was slightly and strongly enhanced in ddm1 and cmt3 (chromomethylase3) protoplasts, respectively, concomitantly with reduction in Tag1 gene body (GB) CHG methylation and increased Tag1 transcription; strong activation of Tag1 was also observed in cmt3 leaves. Notably, in cmt3, but not in ddm1, Tag1 elements were excised out from their original sites and transposed elsewhere in the genome. Our results suggest that dedifferentiation is associated with Tag1 activation and that CMT3 rather than DDM1 plays a central role in restraining Tag1 activation via inducing GB CHG methylation.
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Affiliation(s)
- Asif Khan
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben Gurion 84990, Israel
| | - Narendra Singh Yadav
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben Gurion 84990, Israel
| | - Yaakov Morgenstern
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben Gurion 84990, Israel
| | - Assaf Zemach
- Department of Molecular Biology and Ecology of Plants, Tel-Aviv University, 69978 Tel Aviv, Israel
| | - Gideon Grafi
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben Gurion 84990, Israel.
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Granot G, Morgenstern Y, Khan A, Rapp YG, Pesok A, Nevo E, Grafi G. Internucleosomal DNA fragmentation in wild emmer wheat is catalyzed by S1-type endonucleases translocated to the nucleus upon induction of cell death. Biochim Biophys Acta 2015; 1849:239-46. [PMID: 25497371 DOI: 10.1016/j.bbagrm.2014.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [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: 09/15/2014] [Revised: 11/25/2014] [Accepted: 12/03/2014] [Indexed: 11/17/2022]
Abstract
Leaves of cereal plants display nucleosomal fragmentation of DNA attributed to the action of nucleases induced during program cell death (PCD). Yet, the specific nuclease activity responsible for generating double strand DNA breaks (DSBs) that lead to DNA fragmentation has not been fully described. Here, we characterized a Ca2+/Mg2+-dependent S1-type endonuclease activity in leaves of wild emmer wheat (Triticum dicoccoides Köern.) capable of introducing DSBs as demonstrated by the conversion of supercoiled plasmid DNA into a linear duplex DNA. In-gel nuclease assay revealed a nuclease of about 35 kDa capable of degrading both single stranded DNA and RNA. We further showed that the endonuclease activity can be purified on Concanavalin A and treatment with peptide-N-glycosidase F (PNGase F) did not abolish its activity. Furthermore, ConA-associated endonuclease was capable of generating nucleosomal DNA fragmentation in tobacco nuclei. Since S1-type endonucleases lack canonical nuclear localization signal it was necessary to determine their subcellular localization. To this end, a cDNA encoding for a putative 34 kDa S1-type nuclease, designated TaS1-like (TaS1L) was synthesized based on available sequence data of Triticum aestivum and fused with RFP. Introduction into protoplasts showed that TaS1L-RFP is cytoplasmic 24h post transformation but gradually turn nuclear at 48 h concomitantly with induction of cell death. Our results suggest that DNA fragmentation occurring in leaves of wild emmer wheat may be attributed to S1-type endonuclease(s) that reside in the cytoplasm but translocate to the nucleus upon induction of cell death.
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Affiliation(s)
- Gila Granot
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Yaakov Morgenstern
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Asif Khan
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Yemima Givaty Rapp
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Anat Pesok
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Eviatar Nevo
- Institute of Evolution, University of Haifa, 199 Aba-Hushi Avenue Mount Carmel, Haifa 3498838, Israel
| | - Gideon Grafi
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel.
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Ng C, Morgenstern Y, Purves D. Ocular dominance and retinotopic correspondence enable patent stereopsis. J Vis 2014. [DOI: 10.1167/14.10.968] [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: 11/24/2022] Open
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Morgenstern Y, Rukmini DV, Purves D. Early level receptive field properties emerge from artificial neurons evolved on the basis of accumulated visual experience with natural images. J Vis 2013. [DOI: 10.1167/13.9.1160] [Citation(s) in RCA: 1] [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: 11/24/2022] Open
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Elder JH, Morgenstern Y. Power spectrum classification image analysis reveals localized mechanisms underlying nonlinear detection of narrowband stimuli. J Vis 2010. [DOI: 10.1167/6.6.117] [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: 11/24/2022] Open
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Elder JH, Morgenstern Y, Tabone R. The efficiency of contour grouping. J Vis 2010. [DOI: 10.1167/3.9.118] [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: 11/24/2022] Open
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Morgenstern Y, Elder J. Noise does not shrink the summation region for grating detection. J Vis 2010. [DOI: 10.1167/5.8.477] [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: 11/24/2022] Open
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Granot G, Sikron-Persi N, Gaspan O, Florentin A, Talwara S, Paul LK, Morgenstern Y, Granot Y, Grafi G. Histone modifications associated with drought tolerance in the desert plant Zygophyllum dumosum Boiss. Planta 2009; 231:27-34. [PMID: 19809832 DOI: 10.1007/s00425-009-1026-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 09/21/2009] [Indexed: 05/02/2023]
Abstract
Zygophyllum dumosum Boiss. is a perennial Saharo-Arabian phytogeographical element and a dominant shrub on the rocky limestone southeast-facing slopes of the Negev desert. The plant is highly active during the winter, and semideciduous during the dry summer, i.e., it sheds its leaflets, while leaving the thick, fleshy petiole green and rather active during the dry season. Being resistant to extreme perennial drought, Z. dumosum appears to provide an intriguing model plant for studying epigenetic mechanisms associated with drought tolerance in natural habitats. The transition from the wet to the dry season was accompanied by a significant decrease in nuclear size and with posttranslational modifications of histone H3 N-terminal tail. Dimethylation of H3 at lysine 4 (H3K4)--a modification associated with active gene expression--was found to be high during the wet season but gradually diminished on progression to the dry season. Unexpectedly, H3K9 di- and trimethylation as well as H3K27 di- and trimethylation could not be detected in Z. dumosum; H3K9 monomethylation appears to be prominent in Z. dumosum during the wet but not during the dry season. Contrary to Z. dumosum, H3K9 dimethylation was detected in other desert plants, including Artemisia sieberi, Anabasis articulata and Haloxylon scoparium. Taken together, our results demonstrate dynamic genome organization and unique pattern of histone H3 methylation displayed by Z. dumosum, which could have an adaptive value in variable environments of the Negev desert.
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Affiliation(s)
- Gila Granot
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, 84990, Midreshet Ben-Gurion, Israel
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