Roberts C T, Morse D E
Mol Gen Genet. 1980;180(1):129-34. doi: 10.1007/BF00267361.
We have isolated a series of mutants of Tetrahymena thermophila which are resistant to inhibition of growth by the galactose analog, 2-deoxygalactose. These mutants were obtained after mutagenesis with nitrosoguanidine and the induction of cytogamy to permit the recovery of recessive mutations induced in the germline micronucleus. Resistance to 2-deoxygalactose is correlated with a decreased rate of growth in galactose minimal medium and greatly reduced levels of galactokinase. The resistant phenotype of the mutants is apparently due to the galactokinase deficiency, which prevents the accumulation of toxic phosphorylated metabolites of 2-deoxygalactose. Genetic analyses reveal that the 2-deoxygalactose resistance alleles segregate as single Mendelian loci. The galactokinase-deficient strains described here represent the first mutants in this organism for which the biochemical basis of the mutant phenotype is known. These mutants, as well as others isolated similarly, should be of value in the elucidation of the mechanisms governing galactokinase gene regulation and in improving techniques of selection for other recessive mutations in Tetrahymena.
我们分离出了一系列嗜热四膜虫突变体，它们对半乳糖类似物2-脱氧半乳糖抑制生长具有抗性。这些突变体是在用亚硝基胍诱变并诱导细胞融合以恢复种系小核中诱导的隐性突变后获得的。对2-脱氧半乳糖的抗性与在半乳糖基本培养基中的生长速率降低以及半乳糖激酶水平大幅降低相关。突变体的抗性表型显然是由于半乳糖激酶缺乏，这阻止了2-脱氧半乳糖有毒磷酸化代谢产物的积累。遗传分析表明，2-脱氧半乳糖抗性等位基因作为单个孟德尔位点分离。这里描述的半乳糖激酶缺陷菌株代表了该生物体中首个已知突变体表型生化基础的突变体。这些突变体以及类似分离出的其他突变体，在阐明控制半乳糖激酶基因调控的机制以及改进嗜热四膜虫中其他隐性突变的选择技术方面应具有价值。
