Figure 2.

Rapid nucleolar localization of fluorescent SRP RNA after microinjection into the nucleus. Rhodamine-labeled canine SRP RNA was prepared as detailed in Materials and Methods and microinjected into the nucleus of NRK cells. Two representative experiments are shown. Fluorescence at 3 min (A), 26 min (B), and 66 min (C) after nuclear microinjection. Note the early, transient localization in nucleoli (A), followed by appearance in the cytoplasm (B and C). (D) Phase-contrast micrograph taken at 66 min. Fluorescence at 6 min (E), 33 min (F), and 56 min (G). Note again the early, transient nucleolar localization (E) and subsequent cytoplasmic appearance (F and G). (H) Phase-contrast image taken at 56 min. Results similar to those shown were obtained with fluorescent human SRP RNA.