Word: coli
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Dates: during 1970-1979
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...against the potentially most dangerous experiments. They also provide two principal lines of defense against lesser hypothetical risks. They establish four levels of physical containment; these range from standard laboratory precautions (dubbed "P-l") for experiments in the lowest-risk category-say, injecting harmless bacterial genes into E. coli-to ultrasecure laboratories ("P-4") for work with animal tumor viruses or primate cells. At present, two new P-4 facilities are almost ready. One is a gleaming white trailer parked behind a bar bed-wire fence on the grounds of the National Institutes of Health in Bethesda...
...development of the recombinant DNA technique ushered in a new era of genetic engineering-with all of its promise and possible peril. The lowly organism that currently plays the largest role in the process is the E. coli bacterium. This microbe-a laboratory derivative of a common inhabitant of the human intestine-lends itself to being engineered because its genetic structure has been so well studied. In the first step of the process, scientists place the bacterium in a test tube with a detergent-like liquid. This dissolves the microbe's outer membrane, causing its DNA strands to spill...
Finally, the chimeras are placed in a solution of cold calcium chloride containing normal E. coli bacteria. When the solution is suddenly heated, the membranes of the E. coli become permeable, allowing the plasmid chimeras to pass through and become part of the microbes' new genetic structure. When the E. coli reproduce, they create carbon copies of themselves, new plasmids -and DNA sequences-and all. Thus they become forms of life potentially different from what they had been before-imbued with characteristics dictated not only by their own E. coli genes but also by genes from an entirely different...
...someone will fail-and that a few virulent bugs will slip through the safeguards to multiply in the outside world. Faced with this problem at the Asilomar conference. Geneticist Roy Curtiss III proposed an ingenious solution: Why not convert the standard genetic research organism, a strain of the E. coli bacterium, into a seriously weakened mutant variety that would quickly self-destruct if it escaped the laboratory? Curtiss volunteered to engineer the new bug, and his colleagues agreed to hold off on many of their recombinant DNA experiments until they could be supplied with...
Returning to his laboratory at the University of Alabama Medical Center in Birmingham, Curtiss quickly hit on a way to keep E. coli under control. The microbes must be able to manufacture a protective membrane; without such an outer coat they would swell and burst during normal growth. To keep them from manufacturing a complete coat, Curtiss created an E. coli with a defect in a gene that makes diaminopimelic acid (DAP), an important ingredient of the membrane. The defect made the bugs dependent for their survival upon DAP supplied by scientists...