Molecular basis of cellular functions in Dictyostelium

(1)利用细胞同步化的方法，分离并鉴定了3个基因（dia 1，dia 2，dia 3），它们是在网骨藻细胞从生长向分化过渡过程中特异表达的基因。对它们的功能的分析已经揭示，响应于饥饿，一个新基因dia 2和一个包括rps 4的线粒体基因簇（dia 3）的表达是从细胞周期中的生长/分化检查点（PS点）开始细胞分化所必需的，但是一个新基因（dia 1）的表达在时间上抑制了从PS点开始的分化进程。此外，还发现一种新基因amiB是细胞从生长到分化的过渡所必需的。(2)在网骨藻细胞中，饥饿反应的信号已被证明是通过暂时升高的细胞质Ca 2+浓度（[Ca 2 +]i）来转导的。在这方面，我们认为Dd-GRP 94（Dictyosteoprotein gluco ...更多信息 硒调节蛋白94）可能在分化后期以及饥饿反应中起关键作用。（3）免疫电镜观察发现，胞浆内的蛋白质与高尔基复合体偶联，参与了细胞类型特异性细胞器（PSV ; presnore-specific vacuole）的形成。(4)在盘状杜父藻Ax-2细胞的封闭二维培养物中观察到快速模式化，即外部暗区和内部亮区：外部区基本上由氧化磷酸化的O2阈值形成，而内部细胞主要进行抗氰化物呼吸。当细胞周围的早期丘阶段（前茎和前孢子分化之前）培养在2-D细胞团，pstA细胞，pstB细胞和前孢子细胞出现在一个位置依赖性的方式在外层。在内区，细胞运动似乎是显着imperfect，既不prestalk也不prepore分化发生。此外，在inr区，发现一次分化的前孢子细胞迅速去分化。(5)在盘状杜氏藻二维受限细胞团中观察到的一种新型快速模式化现象是由于反应扩散图灵不稳定性而形成的。这可能是第一个生化结构的发展系统与可控的边界条件。少

(1) Using the good method for cell synchrony, three genes (dia1, dia2, dia3) were isolated and identified as ones specifically expressed during the transition of Dictyostelium cells from growth to differentiation. Analyses of their functions have revealed that in response to starvation the expressions of a novel gene, dia2, and a mitochondrial gene cluster (dia3) including rps4 are required for the initiation of cell differentiation from the growth/differentiation checkpoint (PS point) in the cell cycle, but that the expression of a novel gene (dia 1) rather inhibits temporally the progression of differentiation from the PS point. In addition, a novel gene, amiB, was also found to be required for the transition of cells from growth to differentiation.(2) The signals for starvation response in Dictyostelium cells have been shown to be transduced through a temporally elevated cytoplasmic Ca2+-concentration ([Ca2+]i). In this connection, it was suggested that Dd-GRP94 (Dictyostelium gluco … More se-regulated protein 94) might be cruial in late differentiation as well as in starvation response. During the course of studies, some phosphoproteins resaonsible for starvation response were also found(3) The mitochondrion was Immunoelectron-microscopically found to be participated in the formation of a cell-type-specific organelle (PSV ; presnore-specific vacuole) as the structural basis, coupling with the Golgi complex.(4) Rappid patterning has been observed in confined 2-D cultures of D.discoideum Ax-2 cells as an outer dark zone and a inner light zone : the outer zone is basically formed by the O2 threshold for oxidative phosphorylation, while the inner cells mainly perform cyanide-resistant respiration. When cells around the early mound stage (just before prestalk and prespore differentiation) were cultured in 2-D cell masses, pstA cells, pstB cells and prespore cells arose in a position-dependent manner in the outer layer. In the inner zone, cell motility seemed to be markedly impared and neither prestalk nor prespore differentiation occurred. In sddition, once-differentiated prespore cells were found to dedifferentiate ranidly in the inr zone.(5) A new type of rappid paterning as observed in a 2-D confined cell mass of D.discoideum is formed due to a reaction-diffusion Turing instability. This may be the first biochemical structure in a developmental system with a controllable boundary condition. Less