Spatial distribution of cell fluorescence determined with a diode-matrix (32 x 32 elements) and computer controlled...

A photodiode-matrix with 32 x 32 light-sensitive elements has been used to determine spatial fluorescence intensity of Rhodamine-labelled yeast cells (Saccharomyces cerevisiae). The matrix with electronics was built into one of the oculars of an epifluorescence microscope, and the fluorescence intensity scanned at intervals, determined from a desk-computer. The signals from one image were amplified and stored in a buffer-memory before being put into an auxiliary memory. The sensitivity of each element was calibrated, and linear regression used to determine true fluorescence intensity (256 levels). After background subtraction the spatial intensity was presented on a plotter either on a 0-9 scale, or on a three-dimensional plot (x-y-intensity). The effect of continuous UV-microphotolysis on the fluorescence of Rhodamine-labelled yeast was also determined.