(a) Comparison of fluorescence profiles of sucrose gradient centrifugation experiments performed on E. coli cell lysates containing either −7 or +25 GFP. The majority of −7 GFP is present in the loaded sample (fractions 1 and 2), while +25 GFP peaks at fractions 4–5, corresponding to 15–18% (w/v) sucrose. The fluorescence signals were normalized to the highest value, because the absolute fluorescence of +25 GFP is lower than that of −7 GFP. (b) Comparison of fluorescence (and absorption) profiles of sucrose gradient centrifugation experiments performed on purified DNA (0.2 g/L), and E. coli cell lysates containing +25 GFP with or without additional DNA. (c) Transmission electron microscopy images of uranyl acetate-stained fractions from the cell lysate containing sucrose gradients. Fraction one lacks distinct large structures, whereas fraction 10 shows large aggregates. Ribosomes, spheres of around 25–30 nm diameter, are visible and peak in fraction 5. The scale bar is 100 nm. (d) Elution profiles on a Sephadex 200 of pure ribosomes, ribosomes with +25 GFP, and ribosomes with 1.8x as much +25 GFP, measured as absorbance at 280 nm (e) Fluorescence imaging of tubes containing ribosomes, −7 GFP, ribosomes mixed with −7 GFP, +25 GFP, and ribosomes mixed with +25 GFP. The indicated fluorescent pellet appears after centrifuging the samples. The tube containing only ribosomes is not visible due to lack of fluorescence. (f) Elution profiles of ribosomes, +25 GFP, and ribosomes mixed with +25 GFP, measured as fluorescence at 510 nm; the excitation wavelength was 488 nm. The higher fluorescence of ribosomes mixed with +25 GFP is accompanied by decrease in absorbance at 280 nm; (g) Elution profiles of ribosomes, −7 GFP, and ribosomes mixed with −7 GFP, measured as fluorescence at 510 nm; the excitation wavelength was 488 nm. Unlike for +25 GFP, when ribosomes are mixed with −7 GFP the absorbance at 280 nm remains the same (data not shown).