BUDR DEPENDENCE, MALIGNANCY, AND DIFFERENTIATION

进行实验以测试可转染的细胞的存在。 5-溴脱氧尿苷（BrdU）依赖性细胞中受BrdU控制的癌基因 叙利亚仓鼠黑色素瘤细胞系的突变体 在这条线上， 表型仅在高浓度的 BrdU。在一个相关的方法中，开始了寻找可转染的 例如，具有遗传倾向的肿瘤中的癌基因， 神经纤维瘤病（NF）。 染色体断裂事件与微扰的关系 在人类脆性X染色体的测试中分析了核苷酸代谢的 综合征，这是与精神发育迟滞，其表达 在培养的细胞中， 生物合成从中国仓鼠和中国仓鼠之间的杂交中分离出杂种 细胞和淋巴母细胞样细胞从男性患者与脆性X染色体 综合征 杂交体在约10%的细胞中表达脆性位点。 分裂中期 对5-氟尿嘧啶的毒性作用具有抗性的克隆已经被分离出来 来自中国仓鼠成纤维细胞。 这些突变体的主要病变 似乎是一种改变的CTP合成酶活性， 对CTP的负调控敏感。 对5-羟甲基脱氧尿苷（hmdU）进行了毒性实验 执行。 发现hmdU的主要代谢产物是游离的 嘧啶羟甲基尿嘧啶（hmUra），它是无毒的， 对hmdU毒性的抗性与增加的 将核苷降解为hmUra。 （P）

Experiments were carried out to test for the presence of transfectable oncogenes controlled by 5-bromodeoxyuridine (BrdU) in BrdU-dependent mutants of a Syrian hamster melanoma line. In this line, the transformed phenotype is expressed only in the presence of high concentrations of BrdU. In a related approach, tests were begun to search for transfectable oncogenes in tumors with hereditary disposition, for example, neurofibromatosis (NF). The relationship between chromosomal breakage events and the perturbation of nucleotide metabolism was analyzed in tests on the human fragile X syndrome, which is associated with mental retardation and whose expression in cultured cells is induced by the perturbation of thymidine biosynthesis. Hybrids were isolated from crosses between Chinese hamster cells and lymphoblastoid cells from male patients with the fragile X syndrome. The hybrids expressed the fragile site in approximately 10% of metaphases. Clones resistant to the toxic effects of 5-fluorouracil have been isolated from Chinese hamster fibroblasts. A primary lesion in these mutants appears to be an altered CTP synthetase activity that is no longer sensitive to negative regulation by CTP. Experiments on the toxicity of 5-hydroxymethyldeoxyuridine (hmdU) were performed. It was found that a major metabolite of hmdU is the free pyrimidine hydroxymethyluracil (hmUra), which is not toxic, and also that resistance to hmdU toxicity is correlated with an increased ability to degrade the nucleoside to hmUra. (P)