Computer quantification of intracellular gold particles

We describe the use of image software programs available for both PC and Macintosh computers to quantify the accumulation and distribution of gold-labeled constructs within two-dimensional cell sections. The compartmentalization of a biotinylated-peptide was visualized in radiation-induced fibrosarcoma cells by transmission electron microscopy, using a gold particle-streptavidin conjugate. This study illustrates the ease of tabulating gold particles observed in scanned electron micrographs, using Adobe Photoshop in conjunction with the public domain NIH Image program (Version 1.61). Quantitative information regarding the localization of molecules inside cells is crucial in defining their sites of action and in developing more effective therapeutic agents.