One of the most important recent discoveries in science is the green fluorescent protein, isolated from a bioluminescent jellyfish. The gene that codes for this protein is active in any type of cell, from microbes to humans, producing a "day-glo" dye visible as a bright green light in the microscope. The power of the gene is that by using recombinant DNA technology. GFP can be spliced to any protein, essentially painting that protein green. When such...