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EMBO Plant DNA Repair and Recombination Workshop, Presqu'île de Giens, France 2007
Abstracts of Posters
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P - 1. Analysis of Meiotic Recombination in Rad51 Paralog Mutants in
Arabidopsis.
Kiyomi Abe*, Jean-Yves Bleuyard, Charles White.. CNRS UMR6547, Université Blaise Pascal,
63177 Aubière, France. *Plant Genetic Engineering Research Unit, National Institute of
Agrobiological Sciences, 305-8602 Tsukuba, Japan
Recent studies indicate that two Rad51 paralogs (Xrcc3 and Rad51C) are involved in both
DNA repair and meiotic recombination. To determine further details about the role of
these proteins in meiotic recombination, we analyzed meiosis in atrad51C and xrcc3
mutants. Cytological observation showed apparently normal figures up to
zygotene/pachytene and dramatic abnormalities afterwards through telophase I in both
atrad51C and xrcc3 mutants, indicating that pairing does occur at zygotene but that full
chromosomal synapsis and synaptonemal complex formation depends upon the presence
of the Xrcc3 and Rad51C proteins. Using fluorescence in situ hybridization (FISH) analysis
we observe pairing of centromeres but not of the tested euchromatic region at pachytene
in both mutants. These results suggest that Xrcc3 and Rad51C proteins play important
roles in homologous pairing of the euchromatic regions of chromosomes.
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P - 2. Genome-wide analysis of rye specific chromosome regions
Olena Alkhimova, Marie Kubalakova, Olena Martynenko, Jaroslav Dolezel . National
Academy of Sciences of Ukraine, Institute of Molecular Biology and Genetics, 03143 Kyiv,
Ukraine
Telomeres are specialized chromosome structure, which play important role in
chromosome stability and behaviour. Together with subtelomeres, they form terminal
regions of chromosomes. These are dynamic regions and might help organisms to adapt
to new environmental conditions and promote genomic rearrangements. Large
heterochromatic blocks, which are present near the telomeres of rye chromosomes, are
notoriously difficult for physical mapping because of enrichment by different types of
repetitive DNA sequences. We used wheat-rye addition lines and performed fluorescence
in situ hybridization (FISH) on metaphase stretched flow-sorted chromosomes and
extended DNA fibers for comparison of the terminal regions of the individual rye
chromosomes. Each wheat-rye addition line produced a chromosome-specific large-scale
organization of the tandem repeat arrays. The FISH signals on DNA fibers showed the
multiple patterns of co-linear monomers arrangement of repetitive families as well as of
authentic telomeric probe from Arabidopsis. The primary structure of some spacer
sequences revealed the scrambled regions of similarity to various known repetitive
elements. Using PCR analysis, we determined the DNA sequences adjacent to the tandem
repeats array (spacers). They are enriched of short direct, complementary, inverted and
symmetrical repeats which appear to be associated with recombination events. These
spacers may be a powerful source of tandem array rearrangements. We mapped some of
them on metaphase stretched chromosomes, and the distribution of the signals was in
good agreement with the localization of the breakpoints for deletions and for
translocations of 1R short arm with different wheat chromosomes. This work was
supported by the INTAS grant (03-51-5908).
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