Figure 1.

DCMU prevents degradation of GUS transcripts in the light in C. reinhardtii chloroplast transformants. Algae were grown in 12-h dark/12-h light periods, and total RNA was isolated at the time points indicated. RNA was separated in a 1.3% (w/v) agarose/formaldehyde gel, transferred to a nylon membrane (Zetaprobe, Bio-Rad, Hercules, CA), and hybridized to a ³²P-labeled GUS probe. The membrane was exposed at −80°C to x-ray film (XAR-5, Kodak) with an intensifying screen. DCMU (20 μm final concentration) was added to the cultures 10 min before the onset of light (A and B) and at 6 h of light (6L) (C). Light (L) and dark (D) time points are indicated by white and black bars above the autoradiograms (time point 23D corresponds to 11 h of darkness). MU7 and MU31 are chloroplast transformants harboring rbcL:GUS reporter genes that differ in the sequences upstream of the GUS coding region (see ”Materials and Methods“). C, Control without DCMU.