Figure 2. Dynamics of mRNA Molecules in the Cytoplasm of Mammalian Cells

All images were obtained at a rate of nine images per second, for periods of 22 s, and were deconvolved.

(A) Movements of LacZ-24-hGH mRNAs. Cos cells transiently expressing LacZ-24-hGH mRNAs and the MS2-GFP protein were imaged live. Left: a maximum intensity image projection of 200 time frames on 1 image (“maximal projection”). The scale bar represents 10 µm. Right: panel magnifications: the scale bar represents 2 µm. mRNA track superimposed (green) from each of the indicated boxed regions. See Movies 1 and 2 in the Supplementary Material. The blue arrow points to a “static” particle in the vicinity of a “corralled” mRNA.

(B) Movements of LacZ-24-SV mRNAs. Cos cells were transiently cotransfected with pRSV-Z-24-SV and pMS2-GFP and were imaged as in (A). The scale bar represents 10 µm. Right: panel magnifications: track of mRNA movement superimposed (green) on an enlargement from each of the indicated boxed regions. The scale bar represents 2 µm. (See Movies 1 and 2 in the Supplementary Material).

(C) Velocities of directed motion. For each directed movement of either the LacZ-24-hGH or the LacZ-24-SV mRNA particles, the mean velocity was calculated. The corresponding histograms show a peak at 1.0–1.5 µm/s.