Borth W, Ratner D
Differentiation. 1983;24(3):213-9. doi: 10.1111/j.1432-0436.1983.tb01322.x.
Depending upon environmental conditions, developing cells of the cellular slime mold Dictyostelium discoideum may enter a slug stage in which the cell mass migrates in response to gradients of light and temperature. This developmental stage has often been used to study the divergent differentiation of the cells that will subsequently form spores and stalk in the mature fruiting body. However, still debated is the extent to which the differentiation evident in slug cells is a precondition for development of the mature cells in fruits. Using two-dimensional gel electrophoresis of polypeptides, we have examined the proteins made by prespore and prestalk cells of migrating slugs and by maturing spore and stalk cells. The data indicate that many of the cell-type specific polypeptides in prespore cells of slugs persist as cell-type specific polypeptides of mature spores. Prestalk slug cells, in contrast, do not contain significant amounts of stalk-specific proteins; these proteins appear only during culmination. The precursor cell types also differ in the times and rates of synthesis of cell-specific proteins: prestalk proteins appear much earlier in development than do the prespore, but never reach the levels of expression that the prespore proteins do later in culmination. These findings may explain the well established ability of prespore cells to regulate their cell type more rapidly than do prestalk cells. There are also implications for our general understanding of what is a 'prestalk' gene product.
根据环境条件，细胞黏菌盘基网柄菌发育中的细胞可能进入蛞蝓体阶段，在此阶段细胞团会根据光和温度梯度进行迁移。这个发育阶段常被用于研究随后会在成熟子实体中形成孢子和柄的细胞的分化差异。然而，蛞蝓体细胞中明显的分化在多大程度上是果实中成熟细胞发育的前提条件，这一点仍存在争议。我们利用多肽的二维凝胶电泳技术，检测了迁移中的蛞蝓体的前孢子细胞和前柄细胞以及成熟孢子和柄细胞所产生的蛋白质。数据表明，蛞蝓体前孢子细胞中许多细胞类型特异性多肽会作为成熟孢子的细胞类型特异性多肽持续存在。相比之下，蛞蝓体前柄细胞不含大量柄特异性蛋白质；这些蛋白质仅在发育后期出现。前体细胞类型在细胞特异性蛋白质的合成时间和速率上也有所不同：前柄蛋白在发育中出现的时间比前孢子蛋白早得多，但从未达到前孢子蛋白在发育后期所达到的表达水平。这些发现可能解释了前孢子细胞比前柄细胞更能快速调节其细胞类型这一已被充分证实的能力。这对于我们对“前柄”基因产物的总体理解也有启示意义。
