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  • 1
    Electronic Resource
    Electronic Resource
    RNA editing in plants (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 91 (1994), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Higher plant mitochondrial RNAs undergo predetermined modifications which involve differences of splicing and trimming of the primary transcripts. These post-transcriptional modifications are specific C-to-U changes occurring mostly in the coding regions of mRNAs without changing the reading frame. Editing of mRNAs can lead to the formation or initiation of stop codons. Plant mitochondrial proteins issued from edited mRNAs are more similar to non-plant homologous proteins suggesting that this process is involved in the production of functional polypeptides. RNA editing in non-coding regions are also observed and may represent a new mechanism for modulating gene expression. Three possible biochemical mechanisms can account for RNA editing in plant mitochondria: nucleotide replacement, base exchange and deamination. Although some evidence shows that RNA editing proceeds by a deamination mechanism, several questions remain to be solved: What are the signals recognised by the biochemical machinery for such a specific process? What are the reasons that make an additional process acquired by land plant mitochondria for faithful gene expression?
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1994.tb02986.x
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  • 2
    Electronic Resource
    Electronic Resource
    RNA editing of apocytochrome b (cob) transcripts in mitochondria from two genera of plants (1993)
    Springer
    Current genetics 24 (1993), S. 344-348 
    Details
    ISSN: 1432-0983
    Keywords: Plant mitochondria ; RNA editing ; Apocytochrome b ; Solanum tuberosum, Triticum aestivum, Triticum timopheevi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Editing of the complete coding region of cob transcripts from two genera of plants has been studied by cDNA sequence analysis. Eighteen and nine C residues are edited into U in the mitochondrial transcripts from wheat and potato respectively. Both systems share eight common editing sites; ten codons edited in wheat are “pre-edited” at the genomic level in potato, and one codon edited in potato is “pre-edited” in wheat. Most amino-acid modifications lead to hydrophobic residues and increase the homology between the COB polypeptides and the corresponding protein of other species. In two out of the nine potato cDNA clones, an additional C-to-T modification, which also leads to a change in the encoded amino acid, was identified. Heterogeneity observed at the carboxy-terminus of the COB open reading frame in Triticum aestivum and Triticum timopheevi is not corrected by editing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336787
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  • 3
    Electronic Resource
    Electronic Resource
    Cloning, physical mapping and genome organization of mitochondrial DNA from Cyprinus carpio oocytes (1984)
    Springer
    Molecular genetics and genomics 196 (1984), S. 43-52 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mitochondrial genome from Cyprinus carpio oocytes is a 10.5 megadalton, circular DNA molecule. The carp mitochondrial DNA was cloned in pBR325. Three recombinant plasmids accounted for the entire genome. Mapping of this DNA using 11 different restriction endonucleases is reported here. Both the large and small rRNA genes were then localized using Southern blot analysis. The subunit I of the cytochrome oxidase, the cytochrome b, the tRNAGlu and the URF 4 genes were localized by nucleotide sequence analysis and homology studies with human mtDNA. Our results suggest that a similar gene order has been maintained in the mitochondrial genomes of Chordata and support the hypothesis of a common ancestor for all vertebrate organelle genomes. This study constitutes the first report on the genome organization of a fish mtDNA and provides information for further investigation in connection with sequence determination, replication, and gene expression in carp mitochondria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334090
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  • 4
    Electronic Resource
    Electronic Resource
    DNA methylation of sex chromosomes in a dioecious plant, Melandrium album (1993)
    Springer
    Molecular genetics and genomics 239 (1993), S. 219-224 
    Details
    ISSN: 1617-4623
    Keywords: DNA methylation ; In situ nick-translation ; Lyon hypothesis ; Sex chromosomes ; Melandrium album
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Melandrium album, a dioecious plant species, has two heteromorphic sex chromosomes with the XY constitution typical for male and the XX for female plants. This plant represents an experimental model system of sex determination in which the Y chromosome plays a strongly dominant male role. We present data on the overall transcriptional activities of M. album sex chromosomes. DNA methylation patterns were analysed directly at the level of chromosomes using in situ nick-translation of fixed root mitotic chromosomes after nuclease digestion and in vivo labelling with S-adenosyl-l-[methyl-3H] methionine as donor of methyl groups. Both techniques revealed that the two X chromosomes of female plants had different levels of DNA methylation. Cell treatment with a DNA hypomethylating drug, 5-azacytidine, significantly influenced the labelling densities. These results imply that in female M. album plants, one of the two X chromosomes may be hypermethylated and inactive as described for mammalian cells (Lyon hypothesis). A similar analysis made on male cells displayed a similar relative levels of methylation in autosomes and sex chromosomes, thus indicating the transcriptional activity of both Y and X male chromosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00281621
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    The mat-r open reading frame is transcribed from a non-canonical promoter and contains an internal promoter to co-transcribe exonsnad1e and nad5III in wheat mitochondria (1999)
    Springer
    Plant molecular biology 40 (1999), S. 959-967 
    Details
    ISSN: 1573-5028
    Keywords: maturase ; nad1e-nad5III ; plant mitochondria ; reverse transcriptase ; RNA editing ; trans-intron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of the mat-r locus (mat-r-nad1e-nad5III) was studied in wheat mitochondria. Transcription initiation sites were mapped by S1 protection, primer extension and capping experiments. Two different transcription initiation sites were found. One, non-canonical promoter of low expression level generates a transcript containing the complete mat-r open reading frame (orf), suggesting that this form is the maturase-reverse transcriptase mRNA. A second transcription initiation site, found within the coding region of the mat-r orf, directs the transcription of an abundant co-transcript containing the carboxy-terminal region of the mat-r orf, exon e of the nad1 gene, exon III of the nad5 gene and their respective trans-introns. The co-transcript promoter carries the consensus motif of plant mitochondrial promoters. Analysis of transcript sequences reveals the presence of editing sites in analogous positions in both nad1e and nad5III trans-introns, suggesting that RNA editing is necessary for the trans-splicing process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006296422485
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Impairment of tapetum and mitochondria in engineered male-sterile tobacco plants (1998)
    Springer
    Plant molecular biology 36 (1998), S. 499-508 
    Details
    ISSN: 1573-5028
    Keywords: impairment ; male sterility ; mitochondria ; tapetum ; transgenic plant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Flowers of tobacco transformed with an unedited copy of the mitochondrial atp9 gene sequence fused to the yeast coxIV mitochondrial targeting presequence, showed several anther abnormalities leading to pollen abortion. The gene was expressed in vegetative and reproductive tissues of the plant. Cytological analysis revealed that tapetum development was impaired. Mitochondria of the tapetum cells were severely affected showing characteristic signs of degeneration: loss of cristae and swelling. These mitochondrial modifications were correlated with the presence of the transcript and translated product of the ‘unedited’ atp9 and a significant decrease in oxygen consumption in non-photosynthetic tissues. The main effect of the unedited atp9 expression in transgenic plants was male sterility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005946104983
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