| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1998: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1997: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
The rice lamina inclination test was used to detect the brassinosteroid activity. After treating the rice cultivar with various concentration of compounds according to the standard bioassay system, the magnitude of the angle induced between the leaf and sheath was measured using semicircular protractor. The angles induced after treatments with various concentration of compounds were plotted against the concentrations. In each assay, both treatments with a solvent (DMSO) and a high concentration of brassinolide (10^<-6> M) were included as the negative and positive control, respectively. From each concentration-response curve, the 50% effective concentration EC_<50> (M) was determined for each compound, and the reciprocal logarithm of EC_<50> was used as the activity index. Using this method, we evaluated reproducible EC_<50> values for brassinolide, castasterone, and epibrassinolide to be 9.14, 8.08, and 8.28, respectively. The order of the activity of brassinosteroids is consistent wi
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th the previously reported results. The advantage of this evaluation system in which the concentration-response curve is adopted to estimate the 50% effective concentration is that 1) the standard error of averaged value is small, 2) the constant activity is able to be determined regardless of the experimental conditions, 3) the activity of weak compounds for which the angle exceeding the standard angle (usually 140 degree) is not observed in the measurement is able to be evaluated. With this bioassay system, insect molting hormone agonists such as ecdysone and dibenzoylhydrazines, mammalian hormones such as diethylstilbestrol and glucocorticoids, and other newly synthesized compounds such as oxime and phenyl benzyl ether compounds were screened, although none of compounds tested was not active. Three-dimensional (3-D) structures of 20-hydroxyecdysone and brassinolide were constructed and compared between them, which were different with respect to the torsion angle between alkyl chain at C- 17 position and D-ring of steroid skelton. Less
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