Figure 5.

Chemically induced undermethylation is not sufficient to activate transcription of PCP genes in A. carterae. A. carterae cultures in the exponential phase of growth were transferred to medium supplemented with either 5-azacytidine (200 μm) or ethionine (300 μm), and grown under high-light conditions for 6 weeks, after which DNA was extracted and digested with HpaII (H) or MspI (M) prior to electrophoresis (A), and blotting and hybridization with the PCP probe (B). Lanes C, Controls. C, Slot blots of mRNA prepared from cells treated in the same manner and hybridized with the PCP probe. Numbers to the right of the blots are the corresponding standardized photon equivalents determined by quantitative phosphor imaging. Note that exposure of A. carterae to these compounds resulted in reductions in growth rates of around 35 to 50%, but appeared to otherwise have no adverse effects on morphology or development of the organisms (data not shown). Transfer of treated cells back into normal medium resulted in an immediate return to normal growth rates.