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  • 1
    ISSN: 1432-0983
    Keywords: Sugar beet ; Cytoplasmic male sterility ; Mitochondrial DNA ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitochondrial (mt) DNAs from normal (N) and male sterile (S) cytoplasms of sugar been have been isolated and investigated by electron microscopy. The results showed that mtDNA was composed of a heterogeneous population of circular molecules. Their contour lengths varied from 0.28 to 51 μm, but unlike in the case of maize, a large difference was not observed in the distribution of molecular classes greater than 1.0 μm between N and S cytoplasms of sugar beet. On the other hand, N and S cytoplasms were shown to contain their own characteristic combinations of small circular mtDNA species with lengths between 0.28 μm and 0.6 μm. Mitochondrial DNAs from various sources of male-sterile cytoplasms were analyzed by agarose gel electrophoresis to determine the extent of cytoplasmic variation. Additional low molecular weight DNA bands appeared in all male-sterile lines examined, and as a result, three distinctive banding patterns were recognized. These data are in general agreement with those based upon restriction endonuclease digestion of mt and chloroplast DNAs and the genetic analysis of fertility restoration in test crosses.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0983
    Keywords: Sugar beet ; Cytochrome oxidase subunit II gene ; Cytoplasmic male sterility ; Mitochondrial genome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have cloned and sequenced the cytochrome oxidase subunit II (coxII) gene from both normal and cytoplasmic male-sterile (CMS) sugar beet. The normal coxII (designated NcoxII) locus was found to be located 1491 bp upstream from the gene for cytochrome oxidase subunit I (coxI) on the same DNA strand and to have a 1463 bp intron which split the coding sequence into two exons (382 and 398 bp). The COXII protein contains 260 amino acid residues. We have also found two copies of the coxII gene (ScoxII-1 and ScoxII-2) to be present in the CMS genome. Our results suggest that the NcoxII gene diverges completely from the ScoxII-1 and ScoxII-2 genes 50 bp 5′ to the ATG start codon. In addition, the ScoxII-1 and ScoxII-2 sequences could be readily discriminated from each other by the 3′ end and the immediately adjacent flanking sequences of the gene: the 3′ divergence results in a 101 codon extension of the ScoxII-2 ORF. Northern blot analysis demonstrates that the coxII gene exhibits altered transcript patterns in CMS compared with normal sugar beet. Different genomic arrangements of the coxII gene are considered to be the result of extensive intra-and inter-molecular recombination events involving the repeated DNA elements in the mitochondrial genome.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0983
    Keywords: Mitochondria ; tRNA genes ; Tomato ; Transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleotide sequences of tRNAAsn (GUU) and tRNATyr (GUA) genes from tomato mitochondria and their flanking regions have been determined. The tomato mitochondrial tRNAAsn gene is located 2.1 kb downstream from the tRNACys gene reported previously (Izuchi and Sugita 1989) and shows a nearly complete identity with the corresponding chloroplast gene. The tRNATyr gene, which shows only 73% homology with the corresponding chloroplast gene, has to be considered a “native” mitochondrial tRNA gene and is 535 bp from the “chloroplast-like” tRNAAsn gene on the same strand. Northern hybridization analysis revealed that the three tRNA genes are transcribed in tomato mitochondria. Southern hybridization analysis of tomato, sugar beet, rice and wheat mitochondrial DNAs, with oligonucleotide probes for mitochondrial or chloroplast tRNA genes, demonstrated that the mitochondrial tRNACys gene found in tomato is present in dicot plants but not in monocots. On the other hand, a chloroplast-like tRNACys gene exists in monocot plants.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1335
    Keywords: Key words Breast cancer ; Cyclin D1 ; Cyclin-dependent kinase 4 ; Oestrogen receptor ; Proliferation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Cyclin D1 (CCND1) and its catalytic partner cyclin-dependent kinase 4 (cdk4) are known to play important roles in the G1/S check point of the cell cycle, and CCND1 overexpression has been reported to correlate with progression and prognosis of breast cancers. Oestrogen receptor (ER) levels determine the proliferative response to oestrogen by regulating binding. It has been postulated that CCND1 and cdk4 exert effects on mammary carcinogenesis in co-operation with ER. Patients and methods: CCND1 and cdk4 overexpression in 117 breast cancer cases with long-term follow-up were investigated by means of immunohistochemistry and differential polymerase chain reaction (PCR), using formalin-fixed and paraffin-embedded samples, and compared with ER status and mitotic indices. Additional Western blotting and reverse transcription (RT)/PCR/Southern blot hybridization were performed for 4 breast cancer cell lines and 15 fresh-frozen breast cancer samples to confirm CCND1 and cdk4 data. Results: Immunohistochemically 27 cases were CCND1-positive (23.0%), and CCND1 amplification was evident in 21 (21/86; 24.4%). The two methods in combination demonstrated 37 cases (31.6%) to be positive for CCND1 overexpression. Western blotting revealed 60% of samples of fresh tissue to overexpress CCND1, corresponding well with the results of RT-PCR. There was thus a strong discrepancy between results for paraffin block and fresh samples, probably because of the short life of CCND1. In the case of cdk4, the respective percentages for positive cases were 54.7% and 73%. CCND1 and cdk4 overexpression (P 〈 0.0001), and CCND1 and ER positivity (P = 0.0128) correlated. In addition, samples overexpressing CCND1, cdk4 and ER tended to have slightly lower proliferative activity than samples where these were absent. However, no association with clinicopathological parameters was evident. cdk4 overexpression had no linkage with ER status or clinicopathological status. Neither CCND1 nor cdk4 expression affected prognosis. Conclusion: CCND1 overexpression does not correlate with cancer progression or prognosis or with mitotic activity. The results may suggest that an excess accumulation of CCND1 in breast cancer cells tends to suppress entry into the S phase of the cell cycle.
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  • 5
    ISSN: 1432-2307
    Keywords: Key words Gastric carcinoma ; Epstein-Barr virus ; Oncogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Five hundred and thirteen cases of gastric carcinoma were investigated for the presence of viral RNA, and the clinico-pathological data, geno-type, BamHIF restriction fragment polymorphism (RFLP) and specific LMP-1 30 bp gene deletion were also examined. EBVs detected in lymphocytes in 20 normal gastric mucosa, 7 lymphoma cell lines (LCLs) maintained in severe combined immunodeficiency (SCID) mice and 18 non-Hodgkin’s lymphomas were compared with those in the gastric carcinoma cases. Thirty-three cases (6.4%) were demonstrated to be positive for EBV by means of EBER-1 RNA in situ hybridization. Clinico-pathological data showed no statistically significant difference in histological grading, location of cancer and status of vessel and lymphatic invasion between the EBV-positive and -negative groups, although the former significantly predominated in the submucosal invasion group (submucosal vs mucosal P=0.021; submucosal vs advanced cancer P=0.033). Some of these data were different from corresponding data in earlier reports. In cases that were evaluated by molecular biology, type A, wild-type F and LMP-1 gene deletion predominated except one in 21 informative cases, one in 24 and two in 16, respectively. EBVs detected in lymphocytes in normal gastric mucosa, LCLs in SCID mice and non-Hodgkin’s lymphoma were also predominantly affected by type A, wild-type F and LMP-1 gene deletion with few exceptions. The results indicate a lack of genetic differences among EBVs in gastric carcinoma, normal population, LCLs of SCID mice and non-Hodgkin lymphomas. Some EBV infections in gastric carcinomas may be transient, especially in the submucosal invasion group.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0983
    Keywords: Sugar beet ; atpA ; Cytoplasmic male sterility ; Homologous rearrangement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have characterized the mitochondrial atpA (the alpha subunit of F1-ATPase) gene from male-fertile cytoplasm (cv TK81-0) of sugar beet. The gene is 1518-bp long and encodes a polypeptide of 506 amino acids. The atpA mRNA sequence is modified by three C-to-U RNA editing events, all of which alter the encoded protein sequences. In order to examine the genome organization of the atpA locus in cytoplasmic male-sterile (CMS) sugar beet, atpA-containing clones were isolated from Owen CMS (TK81-MS) and a different source of CMS [I-12CMS(2)] cytoplasm respectively. The sequences of the atpA coding region from TK81-MS and I-12CMS(2) are identical to each other and to the corresponding TK81-0 sequence. However, the TK81-0 and TK81-MS loci diverge completely 47 bp upstream of the initiation codon, resulting in different 5′ transcript termini for the two genes. On the other hand, the point of divergence between the TK81-0 and I-12CMS(2) atpA genes was found to occur after 393 bp 3′ to the TAA stop codon. Our results also show the 3′-flanking sequences of I-12CMS(2) atpA to be present elsewhere in the mitochondrial genomes of TK81-0, TK81-MS and I-12CMS(2), suggesting the possible involvement of these repeated DNA elements in the sequence rearrangements.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0983
    Keywords: Promiscuous DNA ; Beta species mt- and cp-DNA ; trnP-trnW-petG gene cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chloroplast trnP-trnW-petG gene cluster has been identified in the mitochondrial DNA (mtDNA) of sugar beet (Beta vulgaris). The chloroplast-derived trnW gene is transcribed in the mitochondria; the other two genes, however, do not seem to be transcribed. This gene cluster is also present in the mitochondrial genomes of two wild Beta species, B. trigyna and B. webbiana. Sugar beet and the two wild relatives share 100% sequence identity in the coding regions of both the mitochondrial trnP and trnW genes. On the other hand, the petG genes from the wild Beta mtDNAs were found to be disrupted either by a 5-bp duplication (B. trigyna) or by a deletion of the 5′ region (B. webbiana). A data-base search revealed that a conserved sequence of 60 bp is present in the trnP-trnW intergenic region of the mitochondrial genomes of the three Beta species as well as in other higher plants, including wheat and maize, and that the conserved sequence is absent from the chloroplast counterpart. Our results thus favour the hypothesis of a monophyletic origin of the trnP-trnW-petG cluster found in the plant mitochondrial genomes examined.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0983
    Keywords: Key words Mitochondrial DNA ; Repeated sequence ; Recombination ; Soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mitochondrial DNA (mtDNA) fragments that contained cox2 or atp6 loci were cloned from three accessions of wild soybean (Glycine soja) in order to understand the evolutionary changes of mitochondrial genomes in the genus Glycine subgenus Soja. Cox2 was cloned as a single configuration, while atp6 was cloned as either one or two configurations from each accession. Structural variations were detected in the 5′ upstream region of cox2 and in both the 5′ upstream and 3′ downstream regions of atp6. These variations appeared to be the results of recombination events. A comparison of the mtDNA fragments previously cloned from a cultivated soybean (G. max) and a wild soybean revealed various sites of recombination, as well as various combinations of the 5′ and 3′ regions, at the cox2 and atp6 loci. Some of the cloned fragments were found to contain a set of repeated sequences, namely 299-bp and 23-bp repeats in the 5′ region of cox2 or atp6, which were interspersed in the mitochondrial genome in the subgenus Soja. Recombination events involving the 299-bp or 23-bp repeated sequences were shown to account for the generation of structural variations in the 5′ regions of these loci.
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  • 9
    ISSN: 1432-0983
    Keywords: Key words Buckwheat ; Chloroplast DNA ; Inversion ; Inverted repeats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chloroplast genomes in buckwheat species contain large inverted repeats which are at least 4 kbp longer than the majority of those in land plants. The length of the buckwheat inverted repeats was attributable to an additional region located adjacent to the borders of the small single-copy region. We have cloned and sequenced a 5.2-kbp SmaI fragment corresponding to this extra region in the inverted repeats. A homology search revealed that the sequence of the SmaI fragment is highly homologous to one side of the small single-copy region of the inverted repeats in dicot chloroplast DNAs such as tobacco and beechdrops. Interestingly, a 3.7-kbp segment in the middle of the SmaI fragment is inserted in the opposite orientation relative to those of the other dicot species, and 17-bp direct repeats are found located at both the ends of the additional region. These results suggest that expansion of the inverted repeats in buckwheat chloroplast DNA might have been associated with an inversion.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0983
    Keywords: Key words Mitochondrial DNA ; Repeated sequence ; Recombination ; Soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mitochondrial DNA (mtDNA) fragments that contain cox2 and atp6 were cloned from a wild soybean (Glycine soja, accession `B09002') and from a cultivated soybean (G. max, `Harosoy'). Comparison of these DNAs revealed that two sets of repeated sequences, namely, 299 bp and 23 bp, were present in the 5′ regions of cox2 and atp6. The 299-bp and 23-bp repeats were present close to each other on the 5′ flanking region and the 5′ part of the coding region of cox2 in both `Harosoy' and `B09002', as well as on the 5′ flanking region of atp6 in `Harosoy', while these two repeats were separated by a 706-bp nucleotide sequence that contained a truncated sequence of nad3 at the 5′ flanking region of atp6 in `B09002'. The mtDNA configurations upstream from atp6 and cox2 found in `Harosoy' appeared to have been generated from configurations of cox2 and atp6 found in `B09002' via recombination across the 299-bp or 23-bp repeated sequences, or vice versa, in the mitochondrial genome of the hypothetical progenitor of these plants. The 299-bp sequence was found to be interspersed in the mitochondrial genome. Eight loci were identified that include mtDNA configurations that are inter-convertible with each other via recombination across this sequence in `B09002'. Various loci on the mitochondrial genomes of higher plants that harbor segments of the 299-bp repeats in Glycine were identified.
    Type of Medium: Electronic Resource
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