Luporini P, Miceli C, Ortenzi C, Vallesi A
Department of Molecular, Cellular, and Animal Biology, University of Camerino, Italy.
Dev Genet. 1992;13(1):9-15. doi: 10.1002/dvg.1020130103.
Euplotes raikovi, like other ciliates, passes through a postconjugal immaturity, operatively identified by an apparent cell inability to form mating pairs under experimental conditions that are the same as those used for inducing mating at maturity. In cells homozygous for the gene mat-2, which controls the pheromone Er-2, Er-2 mRNA synthesis and mature Er-2 secretion were shown to start from the very beginning of the life cycle and continue throughout immaturity, although to extents estimated to be 5- to 10-fold lower than at maturity. In addition, experiments of 125I-Er-2 binding and crosslinking provided evidence that autocrine pheromone-binding sites, showing values of the dissociation constant of the order of 10(-9) M, are on the surface of immature cells. The number of these sites per cell was estimated to increase from less than 10(6) per cell of 5-7 fissions of age, to about 16 x 10(6) at maturity. These results were taken to suggest that a pheromone-receptor production is stimulated during immaturity by autocrine pheromone binding to cells and that this production might be essential for the development of a pheromone-receptor density high enough to transform the cell from "immature" to "adult," that is competent to respond as well to pheromones of conspecific, genetically different cells.
莱氏游仆虫（Euplotes raikovi）与其他纤毛虫一样，会经历接合后的不成熟期，在与诱导成熟时相同的实验条件下，细胞明显无法形成配对，这可作为该不成熟期的有效判定。在控制信息素Er-2的mat-2基因纯合的细胞中，Er-2 mRNA合成和成熟Er-2分泌从生命周期一开始就开始，并在整个不成熟期持续进行，尽管其程度估计比成熟时低5至10倍。此外，125I-Er-2结合和交联实验提供了证据，表明自分泌信息素结合位点的解离常数约为10^(-9) M，位于未成熟细胞表面。每个细胞这些位点的数量估计从5至7个分裂龄的每个细胞少于10^6个，增加到成熟时约16×10^6个。这些结果表明，在不成熟期，自分泌信息素与细胞结合会刺激信息素受体的产生，并且这种产生对于形成足够高的信息素受体密度可能至关重要，该密度可使细胞从“不成熟”转变为“成熟”，即能够对同种、基因不同细胞的信息素做出反应。
