Calcium levels correlate with cell cycle phase and affect the level of the cyclin B transcript in Dictyostelium discoideum

Abstract

In pre-aggregation amoebae of Dictyostelium discoideum, phenotypic differences with respect to cellular Ca²⁺ and cell cycle phases are known to bias post-aggregative cell-type choice. Using chlortetracycline fluorescence as an indicator, we found that cellular Ca²⁺ is highest at the S phase of the cell cycle. Upon increasing the level of Ca²⁺ with the help of the calcium ionophore A23187, there is a significant decrease in the cyclin B (clb1) mRNA level; the cdc2 mRNA level shows a marginal decrease. These results suggest that the effect of Ca²⁺ and the cell cycle on cell fate could be exerted at the level of transcription, or message stability, of specific genes.