| Budget Amount *help |
¥12,100,000 (Direct Cost: ¥12,100,000)
Fiscal Year 2000: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1999: ¥10,200,000 (Direct Cost: ¥10,200,000)
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| Research Abstract |
The identification of microsporidian parasites has been based on morphological characters observed with light and electron microscopy. Pulsed-field gel electrophoresis has recently provided an alternative for not only the investigation of chromosomes in small single-celled organisms but also the identification of microsporidians. On the other hand, microsporidians used in those studies were not cloned ones. Mixed infection of microsporidians has been known from the diseased silkworm larvae. In this study, the interaction of the parasites in insect hosts and insect cell cultures under mixed infection was investigated first and estimate of the karyotype of the cloned microsporidians was made by light microscopy. Then, we presented data from pulsed-field gel electrophoresis of cloned microsporidians and the intra- and inter-specific variations of entomophathogenic microsporidians was discussed.
Both in the silkworm and in the Spodoptera frugiperda SF21AEII cell culture, Nosema bombycis NIS
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001 dominated on the other microsporidians, Nosema sp. NIS M11 and Vairimorha sp. NIS M12, when it was involved in the mixed infections, However, the dominant did not eliminate the minor ones by competition and microsporidians could co-exist in the same host. It was, therefore, strongly suggested that cloning of microsporidians would be important when the characterization and identification of the parasites were discussed.
Several clones of those microsporidians in insect cell cultures were established by a limiting dilution method and attempt to estimate the number of chromosomes for the vegetative cells of cloned microsporidians was made by an Axioplan 2 universal microscope. Thirteen chromosomes were visualizied for the microsporidian, Vairimorpha sp. NIS M12. In genomic DNA analysis of microsporidia, it was clarified that alkali EDTA solution treatment of spore was needed for genome extraction from Brazilian isolates. The banding patterns were different among the species of microsporidia in pulse-field gel electrophoresis, suggesting that this method useful tool for identification of microsporidia. Established protocol in this report could apply for all isolates used, and this restult demnonstrated the importance of cloning. Less
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