1
|
Damri M, Granot G, Ben-Meir H, Avivi Y, Plaschkes I, Chalifa-Caspi V, Wolfson M, Fraifeld V, Grafi G. Senescing Cells Share Common Features with Dedifferentiating Cells. Rejuvenation Res 2009; 12:435-43. [DOI: 10.1089/rej.2009.0887] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Meytal Damri
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Beer-Sheva, Israel and Midreshet Ben-Gurion, Israel
- The Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Center for Multidisciplinary Research on Aging, Ben-Gurion University of the Negev, Beer-Sheva, Israel and Midreshet Ben-Gurion, Israel
| | - Gila Granot
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Beer-Sheva, Israel and Midreshet Ben-Gurion, Israel
| | - Hagit Ben-Meir
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Beer-Sheva, Israel and Midreshet Ben-Gurion, Israel
| | - Yigal Avivi
- Department of Plant Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Inbar Plaschkes
- The National Institute for Biotechnology, Ben-Gurion University of the Negev, Beer-Sheva, Israel and Midreshet Ben-Gurion, Israel
| | - Vered Chalifa-Caspi
- The National Institute for Biotechnology, Ben-Gurion University of the Negev, Beer-Sheva, Israel and Midreshet Ben-Gurion, Israel
| | - Marina Wolfson
- The Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Center for Multidisciplinary Research on Aging, Ben-Gurion University of the Negev, Beer-Sheva, Israel and Midreshet Ben-Gurion, Israel
| | - Vadim Fraifeld
- The Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Center for Multidisciplinary Research on Aging, Ben-Gurion University of the Negev, Beer-Sheva, Israel and Midreshet Ben-Gurion, Israel
| | - Gideon Grafi
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Beer-Sheva, Israel and Midreshet Ben-Gurion, Israel
| |
Collapse
|
2
|
Ben Zvi MM, Negre-Zakharov F, Masci T, Ovadis M, Shklarman E, Ben-Meir H, Tzfira T, Dudareva N, Vainstein A. Interlinking showy traits: co-engineering of scent and colour biosynthesis in flowers. Plant Biotechnol J 2008; 6:403-15. [PMID: 18346094 DOI: 10.1111/j.1467-7652.2008.00329.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The phenylpropanoid pathway gives rise to metabolites that determine floral colour and fragrance. These metabolites are one of the main means used by plants to attract pollinators, thereby ensuring plant survival. A lack of knowledge about factors regulating scent production has prevented the successful enhancement of volatile phenylpropanoid production in flowers. In this study, the Production of Anthocyanin Pigment1 (Pap1) Myb transcription factor from Arabidopsis thaliana, known to regulate the production of non-volatile phenylpropanoids, including anthocyanins, was stably introduced into Petunia hybrida. In addition to an increase in pigmentation, Pap1-transgenic petunia flowers demonstrated an increase of up to tenfold in the production of volatile phenylpropanoid/benzenoid compounds. The dramatic increase in volatile production corresponded to the native nocturnal rhythms of volatile production in petunia. The application of phenylalanine to Pap1-transgenic flowers led to an increase in the otherwise negligible levels of volatiles emitted during the day to nocturnal levels. On the basis of gene expression profiling and the levels of pathway intermediates, it is proposed that both increased metabolic flux and transcriptional activation of scent and colour genes underlie the enhancement of petunia flower colour and scent production by Pap1. The co-ordinated regulation of metabolic steps within or between pathways involved in vital plant functions, as shown here for two showy traits determining plant-pollinator interactions, provides a clear advantage for plant survival. The use of a regulatory factor that activates scent production creates a new biotechnological strategy for the metabolic architecture of fragrance, leading to the creation of novel genetic variability for breeding purposes.
Collapse
Affiliation(s)
- Michal Moyal Ben Zvi
- The Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel
| | | | | | | | | | | | | | | | | |
Collapse
|
3
|
Grafi G, Ben-Meir H, Avivi Y, Moshe M, Dahan Y, Zemach A. Histone methylation controls telomerase-independent telomere lengthening in cells undergoing dedifferentiation. Dev Biol 2007; 306:838-46. [PMID: 17448460 DOI: 10.1016/j.ydbio.2007.03.023] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2007] [Revised: 03/09/2007] [Accepted: 03/18/2007] [Indexed: 11/21/2022]
Abstract
Cellular dedifferentiation underlies topical issues in biology such as regeneration and nuclear cloning and has common features in plants and animals. In plants, this process characterizes the transition of differentiated leaf cells to protoplasts (plant cells devoid of cell walls) and is accompanied by global chromatin reorganization associated with reprogramming of gene expression. A screen for mutants defective in proliferation and callus formation identified kyp-2-a mutant in the KRYPTONITE (KYP)/SUVH4 gene encoding a histone H3 lysine 9 (H3K9) methyltransferase. Analysis of telomere length revealed stochastic telomerase-independent lengthening of telomeres in wild type but not in kyp-2 protoplasts. In kyp-2 mutant, telomeric repeats were no longer associated with dimethylated H3K9. The Arabidopsis telomerase reverse transcriptase (tert) mutant displayed accelerated proliferation despite its short telomeres, though it also showed accelerated cell death. Microarray analysis uncovered several components of the ubiquitin proteolytic system, which are downregulated in kyp-2 compared to wild-type protoplasts. Thus, our results suggest that histone methylation activity is required for the establishment/maintenance of the dedifferentiated state and/or reentry into the cell cycle, at least partly, through activation of genes whose products are involved in the ubiquitin proteolytic pathway. In addition, our results illuminate the complexity of cellular dedifferentiation, particularly the occurrence of DNA recombination that can lead to genome instability.
Collapse
Affiliation(s)
- Gideon Grafi
- Albert Katz Department of Dryland Biotechnologies, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel.
| | | | | | | | | | | |
Collapse
|
4
|
Zemach A, Li Y, Ben-Meir H, Oliva M, Mosquna A, Kiss V, Avivi Y, Ohad N, Grafi G. Different domains control the localization and mobility of LIKE HETEROCHROMATIN PROTEIN1 in Arabidopsis nuclei. Plant Cell 2006; 18:133-45. [PMID: 16361394 PMCID: PMC1323489 DOI: 10.1105/tpc.105.036855] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Plants possess a single gene for the structurally related HETEROCHROMATIN PROTEIN1 (HP1), termed LIKE-HP1 (LHP1). We investigated the subnuclear localization, binding properties, and dynamics of LHP1 proteins in Arabidopsis thaliana cells. Transient expression assays showed that tomato (Solanum lycopersicum) LHP1 fused to green fluorescent protein (GFP; Sl LHP1-GFP) and Arabidopsis LHP1 (At LHP1-GFP) localized to heterochromatic chromocenters and showed punctuated distribution within the nucleus; tomato but not Arabidopsis LHP1 was also localized within the nucleolus. Mutations of aromatic cage residues that recognize methyl K9 of histone H3 abolished their punctuated distribution and localization to chromocenters. Sl LHP1-GFP plants displayed cell type-dependent subnuclear localization. The diverse localization pattern of tomato LHP1 did not require the chromo shadow domain (CSD), whereas the chromodomain alone was insufficient for localization to chromocenters; a nucleolar localization signal was identified within the hinge region. Fluorescence recovery after photobleaching showed that Sl LHP1 is a highly mobile protein whose localization and retention are controlled by distinct domains; retention at the nucleolus and chromocenters is conferred by the CSD. Our results imply that LHP1 recruitment to chromatin is mediated, at least in part, through interaction with methyl K9 and that LHP1 controls different nuclear processes via transient binding to its nuclear sites.
Collapse
Affiliation(s)
- Assaf Zemach
- Department of Plant Sciences, Weizman Institute of Science, Rehovot, Israel
| | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Zemach A, Li Y, Wayburn B, Ben-Meir H, Kiss V, Avivi Y, Kalchenko V, Jacobsen SE, Grafi G. DDM1 binds Arabidopsis methyl-CpG binding domain proteins and affects their subnuclear localization. Plant Cell 2005; 17:1549-58. [PMID: 15805479 PMCID: PMC1091773 DOI: 10.1105/tpc.105.031567] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2005] [Accepted: 03/14/2005] [Indexed: 05/21/2023]
Abstract
Methyl-CpG binding domain (MBD) proteins in Arabidopsis thaliana bind in vitro methylated CpG sites. Here, we aimed to characterize the binding properties of AtMBDs to chromatin in Arabidopsis nuclei. By expressing in wild-type cells AtMBDs fused to green fluorescent protein (GFP), we showed that AtMBD7 was evenly distributed at all chromocenters, whereas AtMBD5 and 6 showed preference for two perinucleolar chromocenters adjacent to nucleolar organizing regions. AtMBD2, previously shown to be incapable of binding in vitro-methylated CpG, was dispersed within the nucleus, excluding chromocenters and the nucleolus. Recruitment of AtMBD5, 6, and 7 to chromocenters was disrupted in ddm1 and met1 mutant cells, where a significant reduction in cytosine methylation occurs. In these mutant cells, however, AtMBD2 accumulated at chromocenters. No effect on localization was observed in the chromomethylase3 mutant showing reduced CpNpG methylation or in kyp-2 displaying a reduction in Lys 9 histone H3 methylation. Transient expression of DDM1 fused to GFP showed that DDM1 shares common sites with AtMBD proteins. Glutathione S-transferase pull-down assays demonstrated that AtMBDs bind DDM1; the MBD motif was sufficient for this interaction. Our results suggest that the subnuclear localization of AtMBD is not solely dependent on CpG methylation; DDM1 may facilitate localization of AtMBDs at specific nuclear domains.
Collapse
Affiliation(s)
- Assaf Zemach
- Department of Plant Sciences, Weizman Institute of Science, Rehovot 76100, Israel
| | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Avivi Y, Morad V, Ben-Meir H, Zhao J, Kashkush K, Tzfira T, Citovsky V, Grafi G. Reorganization of specific chromosomal domains and activation of silent genes in plant cells acquiring pluripotentiality. Dev Dyn 2004; 230:12-22. [PMID: 15108305 DOI: 10.1002/dvdy.20006] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [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: 11/10/2022] Open
Abstract
The transition from leaf cells to protoplasts (plant cells devoid of cell walls) confers pluripotentiality coupled with chromatin reorganization. Here, we sought to identify remodeled chromosomal domains in Arabidopsis protoplasts by tracking DNA sequences undergoing changes in DNA methylation and by identifying up-regulated genes. We observed a reduction in DNA methylation at a pericentromeric region of chromosome 1, and up-regulation of several members of the NAC (NAM/ATAF1/CUC2) domain family, two of which are located near the telomeric region of chromosome 1. Fluorescence in situ hybridization (FISH) analysis demonstrated that both pericentromeric and telomeric subdomains underwent chromatin decondensation. This decondensation is subdomain-specific inasmuch as centromeric repeats remained largely unchanged, whereas the 18S rDNA underwent condensation. Within the pericentromeric subdomain, VIP1, a gene encoding a b-Zip nuclear protein required for Agrobacterium infectivity, was transcriptionally activated. Overexpression of this gene in tobacco resulted in growth retardation and inhibition of differentiation and shoot formation. Altogether, our data indicate that acquisition of pluripotentiality involves changes in DNA methylation pattern and reorganization of specific chromosomal subdomains. This change leads to activation of silent genes whose products are involved in acquisition or maintenance of pluripotentiality and/or the ensuing fate of the cell.
Collapse
Affiliation(s)
- Yigal Avivi
- Department of Plant Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | | | | | | | | | | | | | | |
Collapse
|
7
|
Abstract
OBJECTIVES to determine whether irradiation is an independent risk factor for carotid atherosclerosis, and propose guidelines for patient follow-up. DESIGN a retrospective case control study. MATERIALS AND METHODS two groups of patients with severe carotid artery stenosis (>70%) were compared: 30 post-neck irradiation patients, and a control group of 100 patients with no history of neck irradiation. Disease location and severity were assessed by duplex. The relationship between atherosclerotic risk factors, time since irradiation and carotid artery disease was examined. RESULTS the average age of study group patients was 67 years (43-86) compared to 69 years (46-89) in the control group. The average interval from irradiation to diagnosis was 14 years (3-53) (median 12.5 years). The study group suffered less from diabetes, ischaemic heart disease, and peripheral vascular disease ( p<0.02). There were no significant differences among risk factors with respect to age, gender, smoking, hypertension, and hypercholesterolemia. Post-neck irradiation patients had a significantly higher prevalence of bilateral disease (p=0.02), and a higher rate of common carotid artery lesions (p<0.002). CONCLUSIONS neck irradiation should be considered a risk factor for occlusive carotid artery disease. Preoperative angiographic study should be considered, due to frequent involvement of the common carotid artery.
Collapse
Affiliation(s)
- M Halak
- Department of Vascular Surgery, Carmel Medical Center, Haifa, Israel
| | | | | | | | | | | |
Collapse
|
8
|
|
9
|
Tzfira T, Ben-Meir H, Vainstein A, Altman A. Highly efficient transformation and regeneration of aspen plants through shoot-bud formation in root culture. Plant Cell Reports 1996; 15:566-71. [PMID: 24178519 DOI: 10.1007/bf00232454] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/1995] [Revised: 09/08/1995] [Indexed: 05/17/2023]
Abstract
The natural capacity of aspen (Populus tremula L.) roots for direct shoot-bud regeneration was harnessed to establish a highly efficient transformation and regeneration procedure that does not require a pre-selection stage on antibiotics. Aspen stem segments were transformed using wildtype Agrobacterium rhizogenes (LBA9402) with the binary p35SGUSINT plasmid carrying the genes coding for β-glucuronidase (GUS) and neomycin phosphotransferase II. High levels of transient GUS expression were found in the basal cut surface of 87% of the segments, and 98% of these formed well-developed adventitious roots. Proliferating root cultures were established in liquid culture, and GUS expression was found in 75% of the roots. Shoot-bud regeneration in root cultures was very high: 99% of the roots yielded shoot-buds (4.3 buds per root), of which 91% expressed GUS. Southern blot analysis and polymerase chain reaction confirmed the transgenic nature of the plants expressing GUS. Kanamycin resistance of transformants was tested with respect to callus growth and bud regeneration. Callus from transgenic plants exhibited a high growth rate in the presence of up to 100 μg/μl kanamycin, and bud regeneration from transformed roots occurred in the presence of up to 30 μg/μl kanamycin. Callus and buds from control (non-transformed) plants failed to proliferate or regenerate, respectively, in the presence of kanamycin at concentrations above 10 μg/μl. Ninety-four independent clones from different transformation events were established, of which 52 were phenotypically true-to-type.
Collapse
Affiliation(s)
- T Tzfira
- The Hebrew University of Jerusalem, The Kennedy-Leigh Centre for Horticultural Research and The Otto Warburg Center for Biotechnology in Agriculture, 76-100, Rehovot, Israel
| | | | | | | |
Collapse
|
10
|
Vainstein A, Ben-Meir H, Zuker A, Watad A, Scovel G, Ahroni A, Ovadis M. MOLECULAR MARKERS AND GENETIC TRANSFORMATION IN THE BREEDING OF ORNAMENTALS. ACTA ACUST UNITED AC 1995. [DOI: 10.17660/actahortic.1995.420.16] [Citation(s) in RCA: 2] [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: 11/17/2022]
|