| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1999: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
This research was carried out on the following two projects.
I: Horizontal gene transfer from plant to filamentous fungi.
Pathogenic and non-pathogenic filamentous fungi were inoculated on a strain of Arabidopsis thaliana that carried a selectable marker gene. However transfer of the marker gene was not confirmed. Therefore uptake of extra-cellular DNA at more artificial conditions was examined. DNA fragments were adsorbed on quartz sand where they were reported to be resistant to enzymatic degradation, and added to culture medium, but the model species of filamentous fungi, Aspergillus nidulans, could not uptake the molecule. To obtain information on gene transfer from different direction, a gene for the primary determinant of infection between a specific strain of Alternaria alteniata and susceptible apple was cloned and the nucleic acid sequence was determined. Although this gene was more than 20-kb, there was no intron and together with the bias of codon usage, this gene could possib
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ly be horizontally transferred from bacteria.
II: Mechanism of extra-cellular DNA integration in filamentous fungi.
To study on an apparatus for extra-cellular DNA integration that is a prerequisite of the horizontal gene transfer to occur, genes that are involved in recombinational repair of double-strand break of DNA were cloned. One of them; uvsC, which has a critical role for homology search between DNA strands was disrupted in two species offilamentous fungi, and integration profiles during the genetic transformation was analyzed in detail. No homologous integration was detected in the null mutant of this gene and number of site of integration in one transformant was significantly increased, indicated that the product of this gene is involved not only in homologous integration, but ectopic integration as well. Furthermore it was shown that a pathway that catalyze non-homologous integration was effective in the null mutant. Analysis of the remaining cloned genes are now being carried out. Less
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