Resistance kasugamycin

The development of resistance in fungi to kasugamycin has been reported from laboratory experiments, but not in the fields for some years after application of the antibiotic. However, since 1971, the development of a kasugamycin-resistant strain of rice blast fungus in the fields has become a serious problem (31). After kasugamycin resistant strains had been detected in the field, the combined formulations of kasugamycin and chemicals with different action mechanisms havebeen practically used. 

All of Hamao U mezawa s work was closely connected with carbohydrates. The principal compounds that he developed, namely, kanamycin, dibekacin (with the elucidation of the resistance mechanism), kasugamycin, formycin, bleomycin, and anthracyclines, are all glycosides. The l.m.w. enzyme-inhibitors, exemplified by bestatin, are mostly oligopeptides, and are the only exceptions. 

The mode of action of kasugamycin is similar to that of blasticidin S. It inhibits protein synthesis in fungi and bacteria. It inhibits binding of the aminoacyl-tRNA complex to the ribosome (Tanaka et al., 1966), but does not disturb the synthesis of nucleic acids. The inhibitory effect is considerably lower in the liver tissue of rats. The selectivity of toxicity may be due to the particular sensitivity to kasugamycin of the ribosomes of each type of organism. This may also explain the relatively rapid development of resistance to kasugamycin. 

Since 1968, the development of resistant Piricularia oryzae strains has increased in Japan with the increasing use of kasugamycin in rice plantations. In one of the territories, 97% of the pathogens became resistant in 1972, so that in 1973 no kasugamycin was used for protection. Since that time the number of resistant strains has diminished considerably (Misato, 1976). 

As we have already seen in earlier sections, the biosynthesis of the lipoprotein has a few unique features. Its biosynthesis is extremely resistant to puromycin, and its mRNA is also extraordinarily stable. It is clear that the lipoprotein is synthesized on ribosomes, since its biosynthesis is as sensitive to chloramphenicol, tetracycline, sparsomycin, and kasugamycin as the biosynthesis of the other outer membrane proteins. 

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