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  • 1
    ISSN: 1617-4623
    Schlagwort(e): Flavonoids ; Light regulation ; Sn locus ; Tissue-specificity ; Zea mays
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The Sn locus of maize is functionally similar to the R and B loci, in that Sn differentially controls the tissue-specific deposition of anthocyanin pigments in certain seedling and plant cells. We show that Sn shows molecular similarity to the R gene and have used R DNA probes to characterize several Sn alleles. Northern analysis demonstrates that all Sn alleles encode a 2.5 kb transcript, which is expressed in a tissue-specific fashion consistent with the distribution of anthocyanins. Expression of the Sn gene is light-regulated. However, the Sn: bol3 allele allows Sn mRNA transcription to occur in the dark, leading to pigmentation in dark-grown seedlings and cob integuments. We report the isolation of genomic and cDNA clones of the light-independent Sn: bol3 allele. Using Sn cDNA as a probe, the spatial and temporal expression of Sn has been examined. The cell-specific localization of Sn mRNA has been confirmed by in situ hybridization using labelled antisense RNA probes. According to its proposed regulatory role, expression of Sn precedes and, in turn, causes a coordinate and tissue-specific accumulation of mRNA of structural genes for pigment synthesis and deposition, such as A1 and C2. The functional and structural relationship between R, B, Lc and Sn is discussed in terms of an evolutionary derivation from a single ancestral gene which gave rise this diverse gene family by successive duplication events.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1617-4623
    Schlagwort(e): Key wordsR locus ; Sn locus ; Anthocyanins ; Tissue specificity ; Paramutation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The duplicated R and Sn genes are involved in the regulation of the maize anthocyanin biosynthetic pathway, encoding tissue-specific products that are homologous to the helix-loop-helix transcriptional activators. Sn determines the pigmentation of the mesocotyl, leaf basis and pericarp, while R determines pigmentation in various tissues, but not in the mesocotyl. In the progeny derived from test-crosses of R/Sn heterozygous plants, a high frequency of R plants exhibiting mesocotyl pigmentation was observed; these derivatives were defined as R*. In R* plants, the presence of this novel trait was not accompanied by the acquisition of Sn or by gross DNA rearrangements in the R profile. Accordingly, RT-PCR analysis showed that mesocotyl pigmentation in R* was attributable to the resident R gene. The occurrence of R* was observed with all R alleles tested, and was enhanced when a P component was present. The heritability of R* was shown only in the case of the standard R-r allele, which carries a functional P component. In addition, we observed that R* can influence other R alleles, transferring the ability to pigment the mesocotyl. R* is unstable, showing a tendency to return to its original state after a few generations. In R* plants there was a correlation between observed ectopic pigmentation and an increase in the level of A1 transcript but, surprisingly, not in the accumulation of R transcript. The results obtained from the analysis of test crosses of rSn/rΔ plants suggest that an unlinked genetic factor accounts for the ectopic pigmentation. Concomitant occurrence of epigenetic events might explain the observed instability and reversibility noted above. Further study of this phenomenon might help to elucidate the basis of the interaction between homologous and non-homologous regulators.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2014-07-22
    Beschreibung: The c-myc proto-oncogene product, Myc, is a transcription factor that binds thousands of genomic loci. Recent work suggested that rather than up- and downregulating selected groups of genes, Myc targets all active promoters and enhancers in the genome (a phenomenon termed 'invasion') and acts as a general amplifier of transcription. However, the available data did not readily discriminate between direct and indirect effects of Myc on RNA biogenesis. We addressed this issue with genome-wide chromatin immunoprecipitation and RNA expression profiles during B-cell lymphomagenesis in mice, in cultured B cells and fibroblasts. Consistent with long-standing observations, we detected general increases in total RNA or messenger RNA copies per cell (hereby termed 'amplification') when comparing actively proliferating cells with control quiescent cells: this was true whether cells were stimulated by mitogens (requiring endogenous Myc for a proliferative response) or by deregulated, oncogenic Myc activity. RNA amplification and promoter/enhancer invasion by Myc were separable phenomena that could occur without one another. Moreover, whether or not associated with RNA amplification, Myc drove the differential expression of distinct subsets of target genes. Hence, although having the potential to interact with all active or poised regulatory elements in the genome, Myc does not directly act as a global transcriptional amplifier. Instead, our results indicate that Myc activates and represses transcription of discrete gene sets, leading to changes in cellular state that can in turn feed back on global RNA production and turnover.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4110711/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4110711/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sabo, Arianna -- Kress, Theresia R -- Pelizzola, Mattia -- de Pretis, Stefano -- Gorski, Marcin M -- Tesi, Alessandra -- Morelli, Marco J -- Bora, Pranami -- Doni, Mirko -- Verrecchia, Alessandro -- Tonelli, Claudia -- Faga, Giovanni -- Bianchi, Valerio -- Ronchi, Alberto -- Low, Diana -- Muller, Heiko -- Guccione, Ernesto -- Campaner, Stefano -- Amati, Bruno -- 10-0245/Worldwide Cancer Research/United Kingdom -- 268671/European Research Council/International -- England -- Nature. 2014 Jul 24;511(7510):488-92. doi: 10.1038/nature13537. Epub 2014 Jul 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Via Adamello 16, 20139 Milan, Italy [2] Department of Experimental Oncology, European Institute of Oncology (IEO), Via Adamello 16, 20139 Milan, Italy [3]. ; 1] Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Via Adamello 16, 20139 Milan, Italy [2]. ; Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Via Adamello 16, 20139 Milan, Italy. ; Department of Experimental Oncology, European Institute of Oncology (IEO), Via Adamello 16, 20139 Milan, Italy. ; Institute of Molecular and Cell Biology, Singapore 138673, Singapore. ; 1] Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Via Adamello 16, 20139 Milan, Italy [2] Department of Experimental Oncology, European Institute of Oncology (IEO), Via Adamello 16, 20139 Milan, Italy.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25043028" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; B-Lymphocytes/metabolism/pathology ; *Cell Proliferation ; Cell Transformation, Neoplastic/*genetics/pathology ; Chromatin/genetics/metabolism ; Chromatin Immunoprecipitation ; Disease Progression ; Down-Regulation/genetics ; Female ; Fibroblasts/cytology/metabolism ; Gene Expression Profiling ; *Gene Expression Regulation, Neoplastic/genetics ; Genome/genetics ; Lymphoma, B-Cell/*genetics/metabolism/*pathology ; Male ; Mice ; Mitogens/pharmacology ; Promoter Regions, Genetic/genetics ; Proto-Oncogene Proteins c-myc/genetics/*metabolism ; RNA, Messenger/biosynthesis/genetics/metabolism ; Transcription Factors/metabolism ; *Transcription, Genetic/genetics ; Up-Regulation/genetics
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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