Courtesy of David McNeill
The genetically altered bacteria on this plate are easily detected under ultraviolet light. Escherichia coli were transformed with a plas-mid encoding the green fluorescent protein (GFP), which makes the colonies fluoresce under UV light. The transforming plasmid also encodes resistance to the antibiotic ampicillin, which allows the cells to grow on this antibiotic-containing agar dish. But in this image, the ampicillin resistance is leaking out of the transformed colonies, allowing some untransformed, nonfluorescent colonies to grow.
The true workhorses of molecular biology are neither fruit flies nor nematodes, neither budding yeast nor mice. No, the diminutive Escherichia coli has to get that accolade. These bacteria take up foreign DNA in the form of a plasmid or viral vector and make it their own. After thus transforming themselves, they churn out enough copies of the nucleic acid for scientists to collect the material for use in subsequent ...
