Maeda Mineko
Department of Biology, College of General Education, Osaka University, Toyonaka, Osaka 560, Japan.
Dev Growth Differ. 1988 Oct;30(5):573-587. doi: 10.1111/j.1440-169X.1988.00573.x.
It is well known that interconversion between prestalk and prespore cells occurs in 3-dimensional (3-D) isolates of Dictyostelium. The present work was undertaken to examine whether or not the interconversion occurs even in monolayer sheets. The results suggested that in monolayer sheets of either prespore or prestalk cells, the interconversion does not occur. Furthermore, effects of cAMP were examined in relation to the formation or loss of prespore vesicles (PSVs). In monolayer sheets, prespore cells retain their PSVs in the presence of cAMP, though they lose them in its absence. In 3-D masses, however, cAMP induces the conversion into stalk cells, stimulating PSV loss. In the case of prestalk cells, cAMP induces the maturation of prestalk cells to stalk cells in 3-D masses, but it does not induce stalk differentiation in monolayer sheets. 8-Bromo cAMP stimulates the maturation of prespore and prestalk cells into spore and stalk cells, respectively. However, the vegetative and the aggregative cells remain amoeboid even in its presence. These observations suggest that 8-bromo cAMP stimulates the maturation rather than inducing prespore and prestalk differentiation.
众所周知，在盘基网柄菌的三维（3-D）分离物中，前柄细胞和前孢子细胞之间会发生相互转化。目前的研究旨在检验这种相互转化在单层细胞片中是否也会发生。结果表明，在前孢子细胞或前柄细胞的单层细胞片中，不会发生相互转化。此外，还研究了环磷酸腺苷（cAMP）对前孢子囊泡（PSV）形成或消失的影响。在单层细胞片中，前孢子细胞在有cAMP存在时会保留其PSV，而在没有cAMP时则会失去PSV。然而，在三维聚集体中，cAMP会诱导细胞转化为柄细胞，促使PSV消失。对于前柄细胞而言，cAMP在三维聚集体中会诱导前柄细胞成熟为柄细胞，但在单层细胞片中不会诱导柄细胞分化。8-溴环磷酸腺苷（8-Bromo cAMP）分别刺激前孢子细胞和前柄细胞成熟为孢子细胞和柄细胞。然而，即使在其存在的情况下，营养细胞和聚集细胞仍保持变形虫状。这些观察结果表明，8-溴环磷酸腺苷刺激细胞成熟，而不是诱导前孢子细胞和前柄细胞分化。
