| 1. |
- Butenko, Melinka A., et al.
(författare)
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Inflorescence deficient in abscission controls floral organ abscission in Arabidopsis and identifies a novel family of putative Ligands in Plants
- 2003
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Ingår i: The Plant Cell. - : American Society of Plant Biologists. - 1040-4651 .- 1532-298X. ; 15:10, s. 2296-2307
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Tidskriftsartikel (refereegranskat)abstract
- Abscission is an active process that enables plants to shed unwanted organs. Because the purpose of the flower is to facilitate pollination, it often is abscised after fertilization. We have identified an Arabidopsis ethylene-sensitive mutant, inflorescence deficient in abscission (ida), in which floral organs remain attached to the plant body after the shedding of mature seeds, even though a floral abscission zone develops. The IDA gene, positioned in the genomic DNA flanking the single T-DNA present in the ida line, was identified by complementation. The gene encodes a small protein with an N-terminal signal peptide, suggesting that the IDA protein is the ligand of an unknown receptor involved in the developmental control of floral abscission. We have identified Arabidopsis genes, and cDNAs from a variety of plant species, that encode similar proteins, which are distinct from known ligands. IDA and the IDA-like proteins may represent a new class of ligands in plants
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| 2. |
- Stabell, Marianne, et al.
(författare)
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Drosophila dSet2 functions in H3-K36 methylation and is required for development.
- 2007
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Ingår i: Biochem Biophys Res Commun. - 0006-291X. ; 359:3, s. 784-9
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Tidskriftsartikel (refereegranskat)abstract
- Lysine methylation has important functions in biological processes that range from heterochromatin formation to transcription regulation. Here, we demonstrate that Drosophila dSet2 encodes a developmentally essential histone H3 lysine 36 (K36) methyltransferase. Larvae subjected to RNA interference-mediated (RNAi) suppression of dSet2 lack dSet2 expression and H3-K36 methylation, indicating that dSet2 is the sole enzyme responsible for this modification in Drosophila melanogaster. dSet2 RNAi blocks puparium formation and adult development, and causes partial (blister) separation of the dorsal and ventral wing epithelia, defects suggesting a failure of the ecdysone-controlled genetic program. A transheterozygous EcR null mutation/dSet2 RNAi combination produces a complete (balloon) separation of the wing surfaces, revealing a genetic interaction between EcR and dSet2. Using immunoprecipitation, we demonstrate that dSet2 associates with the hyperphosphorylated form of RNA polymerase II (RNAPII).
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| 3. |
- Stabell, Marianne, et al.
(författare)
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The Drosophila G9a gene encodes a multi-catalytic histone methyltransferase required for normal development.
- 2006
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Ingår i: Nucleic Acids Res. - 1362-4962. ; 34:16, s. 4609-21
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Tidskriftsartikel (refereegranskat)abstract
- Mammalian G9a is a histone H3 Lys-9 (H3-K9) methyltransferase localized in euchromatin and acts as a co-regulator for specific transcription factors. G9a is required for proper development in mammals as g9a-/g9a- mice show growth retardation and early lethality. Here we describe the cloning, the biochemical and genetical analyses of the Drosophila homolog dG9a. We show that dG9a shares the structural organization of mammalian G9a, and that it is a multi-catalytic histone methyltransferase with specificity not only for lysines 9 and 27 on H3 but also for H4. Surprisingly, it is not the H4-K20 residue that is the target for this methylation. Spatiotemporal expression analyses reveal that dG9a is abundantly expressed in the gonads of both sexes, with no detectable expression in gonadectomized adults. In addition we find a low but clearly observable level of dG9a transcript in developing embryos, larvae and pupae. Genetic and RNAi experiments reveal that dG9a is involved in ecdysone regulatory pathways.
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| 4. |
- Stangeland, Biljana, et al.
(författare)
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AtMBD8 is involved in control of flowering time in the C24 ecotype of Arabidopsis thaliana
- 2009
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Ingår i: Physiologia Plantarum. - : Blackwell Publishing. - 0031-9317 .- 1399-3054. ; 136:1, s. 110-126
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Tidskriftsartikel (refereegranskat)abstract
- The Arabidopsis thaliana accession C24 is a vernalization-responsive, moderately late flowering ecotype. We report that a mutation in AtMBD8, which encodes a protein with a putative Methyl-CpG-Binding Domain (MBD), in C24 background, results in a delay in flowering time during both long and short days. The atmbd8-1 mutant responded to vernalization as wild type (wt) plants. Consistent with a role in modulation of flowering time, an AtMBD8::GUS-reporter construct was expressed in the shoot meristem region and developing leaves. Full-genome transcriptional profiling revealed very few changes in gene expression between atmbd8-1 and wt plants. The expression level of FLC, the major repressor of transition to flowering, was unchanged in atmbd8-1, and in accordance with that, genes upstream of FLC were unaffected by the mutation. The expression level of CONSTANS, involved in photoperiodic control of flowering, was very similar in atmbd8-1 and wt plants. In contrast, the major promoters of flowering, FT, and SOC1, were both downregulated. As FT is a regulator of SOC1, we conclude that AtMBD8 is a novel promotor of flowering that acts upstream of FT in the C24 accession. In contrast to atmbd8-1, the Colombia (Col) SALK T-DNA insertion line, atmbd8-2, did not display a delayed transition to flowering. Transcriptional profiling revealed that a substantial number of genes were differentially expressed between C24 and Col wt seedlings. Several of these genes are also differentially expressed in late flowering mutants. We suggest that these differences contribute to the contrasting effect of a mutation in AtMBD8 in the two ecotypes.
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| 5. |
- Stangeland, Biljana, et al.
(författare)
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Molecular analysis of Arabidopsis endosperm and embryo promoter trap lines : Reporter-gene expression can result from T-DNA insertions in antisense orientation, in introns and in intergenic regions, in addition to sense insertion at the 5′ end of genes
- 2005
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Ingår i: Journal of Experimental Botany. - : Oxford University Press. - 0022-0957 .- 1460-2431. ; 56:419, s. 2495-2505
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Tidskriftsartikel (refereegranskat)abstract
- Random insertions of promoterless reporter genes in genomes are a common tool for identifying marker lines with tissue-specific expression patterns. Such lines are assumed to reflect the activity of endogenous promoters and should facilitate the cloning of genes expressed in the corresponding tissues. To identify genes active in seed organs, plant DNA flanking T-DNA insertions (T-DNAs) have been cloned in 16 Arabidopsis thaliana GUS-reporter lines. T-DNAs were found in proximal promoter regions, 5' UTR or intron with GUS in the same (sense) orientation as the tagged gene, but contrary to expectations also in inverted orientation in the 5' end of genes or in intergenic regions. RT-PCR, northern analysis, and data on expression patterns of tagged genes, compared with the expression pattern of the reporter lines, suggest that the expression pattern of a reporter gene will reflect the pattern of a tagged gene when inserted in sense orientation in the 5' UTR or intron. When inserted in the promoter region, the reporter-gene expression patterns may be restricted compared with the endogenous gene. Among the trapped genes, the previously described nitrate transporter gene AtNRT1.1, the cyclophilin gene ROC3, and the histone deacetylase gene AtHD2C were found. Reporter-gene expression when positioned in antisense orientation, for example, in the SLEEPY1 gene, is indicative of antisense expression of the tagged gene. For T-DNAs found in intergenic regions, it is suggested that the reporter gene is transcribed from cryptic promoters or promoters of as yet unannotated genes.
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