Living Matter Laboratory, Center for Physics and Biology, Rockefeller University, New York, New York, United States of America.
PLoS One. 2007 Feb 14;2(2):e212. doi: 10.1371/journal.pone.0000212.
Dictyostelium amoebae faced with starvation trigger a developmental program during which many cells aggregate and form fruiting bodies that consist of a ball of spores held aloft by a thin stalk. This developmental strategy is open to several forms of exploitation, including the remarkable case of Dictyostelium caveatum, which, even when it constitutes 1/10(3) of the cells in an aggregate, can inhibit the development of the host and eventually devour it. We show that it accomplishes this feat by inhibiting a region of cells, called the tip, which organizes the development of the aggregate into a fruiting body. We use live-cell microscopy to define the D. caveatum developmental cycle and to show that D. caveatum amoebae have the capacity to ingest amoebae of other Dictyostelid species, but do not attack each other. The block in development induced by D. caveatum does not affect the expression of specific markers of prespore cell or prestalk cell differentiation, but does stop the coordinated cell movement leading to tip formation. The inhibition mechanism involves the constitutive secretion of a small molecule by D. caveatum and is reversible. Four Dictyostelid species were inhibited in their development, while D. caveatum is not inhibited by its own compound(s). D. caveatum has evolved a predation strategy to exploit other members of its genus, including mechanisms of developmental inhibition and specific phagocytosis.
当面临饥饿时，粘菌变形虫会启动一个发育程序，在此过程中，许多细胞聚集并形成子实体，子实体由一个由孢子组成的球通过一个细柄支撑。这种发育策略存在多种被利用的形式，包括粘菌洞穴变形虫的显著案例，即使它构成聚集物中细胞的 1/10(3)，它也可以抑制宿主的发育，并最终吞噬它。我们表明，它通过抑制一个被称为尖端的细胞区域来实现这一壮举，该区域组织聚集物发育成子实体。我们使用活细胞显微镜来定义 D. caveatum 的发育周期，并表明 D. caveatum 变形虫有能力吞噬其他粘菌物种的变形虫，但不会相互攻击。D. caveatum 诱导的发育受阻不会影响前孢子细胞或前柄细胞分化的特定标志物的表达，但会停止导致尖端形成的协调细胞运动。抑制机制涉及 D. caveatum 组成性分泌的小分子，并且是可逆的。四种粘菌物种的发育受到抑制，而 D. caveatum 不受自身化合物的抑制。D. caveatum 已经进化出一种捕食策略来利用其属中的其他成员，包括发育抑制和特定吞噬的机制。
