The result: The ratio of oxygen-18 to oxygen-16 was different in water from inside and outside the bacteria. The extent of that difference allowed the scientists to determine that 30 percent of the water inside rapidly growing E. coli came from outside the bacteria and 70 percent of the water was produced by metabolism inside the bacteria.
Ehleringer says the new study will not affect most existing uses of stable isotope analysis because the findings apply only to rapidly growing cells like bacteria, and most uses of stable isotope analysis do not involve fast-growing cells.
Hegg and Kreuzer-Martin say the new findings might make it more complicated to determine where bacteria used in bioterrorism were grown. That isn't true of anthrax, which is spread by spores that are almost dormant. But for live bioweapons spread through the air in an aerosol mist ?bacteria that cause plague, tularemia or Q fever, for example ?the difference in isotope concentrations inside and outside the bacterial cells must be taken into account in trying to identify where the bacteria were grown based on the isotopic signature of the water in which they were cultured.
Findings Suggest a New Way to Study Eating Disorders
"One area where our results could prove very useful is in assessing metabolic activity," Hegg says. "Being able to accurately measure this number is often important in obesity research and understanding eating disorders. The greater the metabolic activity of a cell, the bigger the difference between the 'inside' water and the 'outside' water."
Hegg says a person's metabolic rate now is measured by having them drink water enriched in oxygen-18 and hydrogen-2. Over time, these uncom
Source:University of Utah Public Relations