抄録
A toxic substance named fusarenon was isolated from rice grains infected with Fusarium nivale. The substance, at concentrations of 50μg/ml or higher inhibited completely the division of Tetrahymena pyriformis (ciliated protozoan) in exponentially growing mass culture and in temperature-induced synchronous culture.
From the delay in cell division caused by exposure of the cells to 200μg/ml of f usarenon for 20 min at various stages after the end of the synchronous treatment, it was shown that the cells at 30 min before the synchronous division maximum were most susceptible to the toxic substance. The cells at this stage are known to have completed the syntheses of DNA and m-RNA and be actively synthesizing the specific protein, all of which are indispensable with the forthcoming division.
From pulse-labeling with 3H-thymidine, -uridine or -phenylalanine in the presence of fusarenon at different concentrations, it can be said that fusarenon affects most seriously the protein synthesis. It is, therefore, likely that the blockage of the cellular protein synthesis caused by the toxin may result in the inhibition of cell division.
