Home  About us  Contact
 

Double Strands (double + strand)

Distribution by Scientific Domains
Chemistry75%

Terms modified by Double Strands

  • double strand break
    		•

    Selected Abstracts

    The role of double-strand break-induced allelic homologous recombination in somatic plant cells

    THE PLANT JOURNAL, Issue 3 2002
    Brigitte Gisler
    Summary During meiosis, homologous recombination occurs between allelic sequences. To evaluate the biological significance of such a pathway in somatic cells, we used transgenic tobacco plants with a restriction site for the rare cutting endonuclease I- SceI within a negative selectable marker gene. These plants were crossed with two tobacco lines containing, in allelic position, either a deletion or an insertion within the marker gene that rendered both marker gene and restriction site inactive. After the double-strand break induction, we selected for repair events resulting in a loss of marker gene function. This loss was mostly due to deletions. We were also able to detect double strand break-induced allelic recombination in which the break was repaired by a faithful copying process from the homologue carrying the shortened transgene. The estimated frequency indicates that homologous recombination in somatic cells between allelic sites appears to occur at the same order of magnitude as between ectopic sites, and is thus far too infrequent to act as major repair pathway. As somatic changes can be transferred to the germ line, the prevalence of intrachromatid rearrangements over allelic recombination might be an indirect prerequisite for the enhanced genome plasticity postulated for plants. [source]

    DFT study of the electronic properties of DNA,DNA and PNA,DNA double strands

    INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 15 2006
    Takayuki Natsume
    Abstract The electronic properties of DNA,DNA and PNA,DNA double strands having 3,6 base pairs (bp) were investigated by density functional theory (DFT) calculations. The binding energies and the highest occupied molecular orbital,lowest unoccupied molecular orbital (HOMO,LUMO) energy gaps for the PNA,DNA hybrids in the vapor phase are found to be greater than those for the DNA,DNA hybrids, regardless of the number of base pairs involved. The study supports the experimental finding that PNA displays high affinity toward a complementary DNA and that PNA,DNA strands are much more thermodynamically stable than their DNA,DNA counterparts. The results suggest much higher sensitivity in DNA sequencing with the arrays of PNA than with those of DNA. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source]

    Cover Picture: Chemical Restriction: Strand Cleavage by Ammonia Treatment at 8-Oxoguanine Yields Biologically Active DNA (ChemBioChem 7/2003)

    CHEMBIOCHEM, Issue 7 2003
    Christoph Meyer Dr.
    Abstract The cover picture shows a chemical restriction method in which DNA double strands are cleaved at the position of the artificial base 8-oxoguanine (Goxo). As as result of the mild cleavage conditions, the DNA fragments remain biologically active and can be used in gene cloning experiments. As an example, the lac Z, gene was amplified by PCR with 8-oxoguanine-modified primers, restricted by treatment with ammonia, ligated into a plasmid vector, transformed in Escherichia coli cells, and screened for blue colonies. This method guarantees efficiencies comparable to the standard cloning procedure, and allows the design of any 3, overhang, independent of the sequence of the cloned DNA. Further information can be found in the article by Giese et. al. on pp. 610,614 [source]