Different growth phenotypes of Tetrahymena vorax V(2) microstomes: II: Kinetics of macrostome differentiation

The ciliate Tetrahymena vorax can differentiate from a microstome to a macrostome cell form when exposed to the prey factor "stomatin". Different microstome growth phenotypes have been identified that stopped their growth at significantly different cell densities in stationary phase. The kinetics of macrostome differentiation in the presence of stomatin were recorded in different phenotype microstome populations in different growth stages. The microstomes' competence for macrostome formation increased with decrease of growth rate, but was reduced after entrance of stationary phase. Addition of yeast extract (YE) in the stomatin assay modulated macrostome formation in a phenotype specific manner: Macrostome yields were enhanced in cultures of low stationary density, while in high stationary density cultures, YE inhibited macrostome formation in non exponential populations. This effect was most prominently expressed in late stages of negative growth acceleration. The kinetics of macrostome accumulation was shown to be closely correlated with the age distribution of the respective populations.