Living Image 3.1

F. Fluorescent Imaging
220
Figure F.14 Images of animal tissue autofluorescence in control mice (Nu/nu females)
Animals were fed regular rodent food (top) or alfalfa-free rodent food (bottom). Images were
taken using the GFP, DsRed, Cy5.5, or ICG filter set. The data is plotted in efficiency on the
same log scale.
Figure F.15 shows a comparison of fluorescence and bioluminescence emission in vivo. In
this example, 3× 10 6 PC3M-luc/DsRed prostate tumor cells were injected subcutaneously
into the lower back region of the animal. The cell line is stably transfected with the firefly
luciferase gene and the DsRed2-1 protein, enabling bioluminescent and fluorescent
expression. The fluorescence signal level is 110 times brighter than the bioluminescence
signal. However, the autofluorescent tissue emission is five orders of magnitude higher.
In this example, fluorescent imaging requires at least 3.8× 10 5 cells to obtain a signal above
tissue autofluorescence while bioluminescent imaging requires only 400 cells.
Figure F.15 Fluorescent (left) and bioluminescent (right) images of stably transfected, dualtagged
PC3M-luc DsRed cells.
The images show the signal from a subcutaneous injection of 3x10 6 cells in an 11-week old
male Nu/nu mouse.
NOTE
When you make ROI measurements on fluorescent images, it is important to subtract
the autofluorescence background. For more details, see Subtracting Tissue
Autofluorescence, page 101.