Abstract
Allophycocyanin (APC) was extracted from Anacystis nidulans and examined for its binding affinity towards various cells/nuclei. The various cells and nuclei isolated from human, rat and rabbit blood were stained with APC and examined under fluorescent microscope. Allophycocyanin dye showed high affinity towards nucleus rather than the cell surface. It reacts with the human lymphocytes at high dilution of greater than 10(-6). The APC was seen to have no affinity towards anucleated cells such as RBCs and platelets from human, rat and rabbit. Thus, APC may be used to count nucleated cells and can also be employed as potential diagnostic agent to differentiate nucleated cell from anucleated cells. The study also highlights affinity of APC towards genomic DNA and it has no specificity for any other proteins because it could not stain them and thus could be suitably employed in genomic DNA analysis and may be replaced by harmful chemicals used for staining.