Experiments Challenge Genetic Theory
Hendricks, Melissa, Science News
Experiments challenge genetic theory
For more than 40 years, microbiologists have held that the only bacteria able to survive environmental upheavals, such as abrupt temperature shifts or food shortages, are those that have changed, or mutated, before encountering the stress. But recent experiments may prompt scientists to revise this view. Researchers at the Harvard School of Public Health in Boston say they have shown that bacteria can somehow adopt genetic traits in response to a particular environment, then pass on these acquired characteristics to their offspring.
This field has long remained dormant, says one of the researchers, in part because it is so complicated.
In one set of experiments, reported in the Sept. 8 NATURE, the scientists began with a population of Escherichia coli bacteria incapable of metabolizing the sugar lactose. When such lac.sup.- E. coli mutate to lac.sup.+., they acquire the ability to survive in an environment whose only source of sugar is lactose. The researchers introduced lac.sup.- E. coli to lactose and, not surprisingly, verified established genetic rules: The lac.sup.- E. coli that happened to have mutated to lac.sup.+ before encountering lactose survive. But using complex statistical analysis, the scientists also observed that a small number of bacteria mutate from lac. …