Fig. 2. In vivo measurement of luciferin levels in non-transgenic animals using injectable luciferase plugs. Direct comparison of stationary CCD camera (IVIS^® Spectrum) and PBL readouts.

a Maximal photon flux resulting from three groups of nude mice (n = 5) injected s.c. with 100 µL of luciferase plug in the dorsal area followed by i.p. injection of different doses of luciferin (1.5, 15, and 150 mg/kg) and imaging with the IVIS^® Spectrum. The “blank” group of mice was not injected with luciferin. b Representative images of mice from each luciferin-injected group described in (a). c Experimental setup for the PBL imaging experiment. The portable light detector is placed directly on the area of the luciferase plug upon administration of luciferin. d Maximum signal output from the experiment described in (a) except that the measurements were performed using the portable light detector. Data are presented as the mean ± s. d. (n = 5). Each “n” represents a biologically independent sample. Statistical significance (***P < 0.001; ****P < 0.0001) was calculated using a two-tailed unpaired t-test. Source data is available as a Source Data file for (a and d).