Saxe C L, Firtel R A
Department of Biology, University of California, San Diego, La Jolla 92093.
Dev Genet. 1986;7(2):99-108. doi: 10.1002/dvg.1020070205.
We have analyzed the expression of a series of developmentally regulated genes in the Dictyostelium discoideum strain JC-5. This strain has been previously described as a temperature-sensitive, cohesion-defective derivative of FR17, itself a temporally deranged mutant of wild-type NC-4. At restrictive temperature (27 degrees C), JC-5 initially acquires EDTA-resistant cell contacts but at the time of tip formation (12 hr) loses the ability to make specific cell-cell associations and regresses to an amorphous mound of cells. WE have found that genes preferentially expressed in either prespore or prestalk cells are expressed prior to the appearance of the cohesion defect in JC-5; the specific cell contact system defective in this strain is necessary for neither the proper initiation nor maintenance of expression of either prespore of prestalk genes. We have also found, by use of an in vitro cell suspension system, that JC-5 is temperature-sensitive with respect to gene expression several hours before the defect in cell cohesion is observable. Our data suggest that the defect in JC-5 is due to a specific lesion not in the late cohesion system but rather in a more general component that is required earlier in the developmental process.
我们分析了盘基网柄菌菌株JC - 5中一系列受发育调控基因的表达情况。该菌株先前被描述为FR17的温度敏感型、凝聚缺陷型衍生物，而FR17本身是野生型NC - 4的时间紊乱突变体。在限制温度（27摄氏度）下，JC - 5最初获得对EDTA抗性的细胞接触，但在尖端形成时（12小时）失去形成特定细胞间关联的能力，并退化为无定形的细胞团。我们发现，优先在孢子前细胞或柄细胞前体中表达的基因在JC - 5中凝聚缺陷出现之前就已表达；该菌株中存在缺陷的特定细胞接触系统对于孢子前或柄细胞前体基因表达的正常起始或维持都不是必需的。我们还通过使用体外细胞悬浮系统发现，在细胞凝聚缺陷可观察到之前数小时，JC - 5在基因表达方面对温度敏感。我们的数据表明，JC - 5中的缺陷不是由于后期凝聚系统中的特定损伤，而是由于发育过程早期所需的更普遍成分中的特定损伤。
