Yuyama S, Corff S
J Protozool. 1978 Aug;25(3 Pt 2):408-15. doi: 10.1111/j.1550-7408.1978.tb03916.x.
DNA of Naegleria gruberi strain NEG, grown in axenic culture, forms a band at a density of 1.6912 in CsCl gradient and has a GC content of 31.8%. Incorporation of [3H]thymidine into DNA is much reduced in differentiating Naegleria immediately after the stimulation to transform, primarily because of the reduction in thymidine uptake by differentiating cells. In addition, there is a marked decrease in the rate of incorporation of [3H]thymidine and [3H]uracil into DNA at from 45 to 60 min after the stimulation for differentiation. This decrease in the rate of precursor incorporation into DNA appears to be due to the differentiation-dependent cessation of nuclear DNA synthesis. The differentiated phenotype (the flagellate) emerges at approximately 70 min after the stimulation, and over 90% of the population differentiates within the next 30 min. Synthesis of mitochondrial DNA is detectable until 190 min after the stimulation. Since the S phase of Naegleria lasts approximately 180 min, some cells in the population must cease synthesizing nuclear DNA in the middle of the S phase.
在无菌培养中生长的格氏变形虫NEG菌株的DNA，在氯化铯梯度中形成一条密度为1.6912的条带，其鸟嘌呤-胞嘧啶（GC）含量为31.8%。在刺激转化后，分化中的变形虫立即将[³H]胸苷掺入DNA的量大大减少，这主要是因为分化细胞摄取胸苷的量减少。此外，在刺激分化后45至60分钟，[³H]胸苷和[³H]尿嘧啶掺入DNA的速率显著降低。前体掺入DNA速率的这种降低似乎是由于分化依赖的核DNA合成停止。分化表型（鞭毛虫）在刺激后约70分钟出现，超过90%的群体在接下来的30分钟内分化。直到刺激后190分钟都可检测到线粒体DNA的合成。由于变形虫的S期持续约180分钟，群体中的一些细胞必定在S期中期停止合成核DNA。
