Photometrics high-performance CCD cameras are routinely used for fluorescence in situ hybridization (FISH) applications such as whole-chromosome painting, locus-specific analysis, gene mapping, and comparative genomic hybridization (CGH).
CCD cameras are used primarily because of their ability to "see" beyond the capabilities of the human eye. Visualization of small cDNA clones, CGH experiments, and combinatorially labeled probes all require low-light sensitivity. Specifically, cameras are optically coupled to the microscope such that the pixel-to-pixel resolution matches that of the microscope optics. Gene mapping is therefore limited by the theoretical resolution limit, not by the imaging device.
Finally, the linear fashion in which light intensities are converted allows accurate distribution determination in CGH, precise probe distinction during combinatorial labeling, and detection of weak signals over large backgrounds typical of probes under 1 kilobase in size.
Image courtesy of Photometrics.
Interphase nuclei (blue) above are labeled with fluorescent markers for X and Y (red and green) chromosomes. This color composite image was created from three images acquired at the emission wavelengths corresponding to DAPI (blue), FITC (green), and Texas Red (red).
With the continuing development of new, more powerful tools in molecular biology, using nucleic acid probes to detect the presence of cognate DNA or RNA sequences has become quite routine. Fluorescence in situ hybridization (FISH) employs fluorescent deoxynucleotides to detect the localization of a DNA probe after its hybridization within a fixed cell or tissue preparation. The information derived from FISH can range from whole-chromosome identification to the measurement of gene copy number or the localization of specific mRNA species within the cell.