SCHREIBER R W, DUNCAN R E
J Biophys Biochem Cytol. 1958 Nov 25;4(6):793-806. doi: 10.1083/jcb.4.6.793.
The effects of 5-hydroxyuracil (5-HU) (isobarbituric acid) upon cell elongation, mitosis, and DNA synthesis were studied in Vicia faba roots. 5-HU had no consistent effect upon root elongation. It blocked DNA synthesis (analyzed by photometric measurements of Feulgen dye in nuclei) during the first 6 hours of treatment; the block spontaneously disappeared by the 12th hour of treatment. Uracil and thymine had no effect upon this block of synthesis. Both thymidine and uridine reversed the block in 6 and 9 hours respectively. In all cases blockage of DNA synthesis was followed by inhibition of mitosis (determined by changes in the percentage of cells in mitosis) and resumption of DNA synthesis was followed by resumption of mitosis. Inhibition indices calculated from the mitotic data indicated a competitive relationship between 5-HU and thymidine and 5-HU and uridine. 5-HU is considered to block DNA synthesis by competing with thymidine for sites on enzymes involved in the synthesis. It is suggested that uridine reverses the block in synthesis by undergoing a conversion to thymidine.
在蚕豆根中研究了5-羟基尿嘧啶（5-HU）（异巴比妥酸）对细胞伸长、有丝分裂和DNA合成的影响。5-HU对根伸长没有一致的影响。在处理的前6小时，它阻断了DNA合成（通过对细胞核中孚尔根染料的光度测量分析）；到处理的第12小时，这种阻断自发消失。尿嘧啶和胸腺嘧啶对这种合成阻断没有影响。胸苷和尿苷分别在6小时和9小时逆转了这种阻断。在所有情况下，DNA合成受阻后有丝分裂受到抑制（通过有丝分裂细胞百分比的变化来确定），DNA合成恢复后有丝分裂也恢复。根据有丝分裂数据计算的抑制指数表明5-HU与胸苷以及5-HU与尿苷之间存在竞争关系。5-HU被认为通过与胸苷竞争参与合成的酶上的位点来阻断DNA合成。有人提出尿苷通过转化为胸苷来逆转合成阻断。
