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"We used C. elegans to study the effect of diet on a host and found that one type of food was able to greatly increase resistance to multiple stress factors such as heat and free radicals and pathogens, "says lead author Natasha Kirienko, assistant professor of biological sciences at Rice University.
The discovery was a surprise for Kirienko's team, who first noticed the effect in experiments aimed at investigating the pathogenesis mechanisms of Pseudomonas aeruginosa ( P aeruginosa ), a potentially fatal disease that infects approximately 51,000 US hospital patients each year, according to the Centers for Disease Control.
His laboratory, like thousands of others around the world, uses C. elegans as a model organism to study the effects of diseases, drugs, toxins and other processes that affect humans and animals. In many C. elegans worm research laboratories eat Escherichia coli ( E. coli ), a common bacterium of the human intestine which is itself a model organism.
"We found that the transition between E. coli The OP50 strain and the HT115 strain drastically changed the worm's tolerance to stress," says Kirienko. It says that it took about two years of follow-up studies to isolate the biochemical mechanism of stress and resistance to pathogens.
"The fundamental difference between the two diets is the ability of HT115 and OP50 to acquire B12 from the environment," says lead co-author Alexey Revtovich, a research scientist. "We have shown that HT115 is much more efficient in this, producing about eight times the protein needed to harvest B12 than OP50."
Researchers have done numerous tests to confirm their results and rule out other possible mechanisms for the effect. They also found that C. elegans on an HT115 diet resisted infection by another deadly human pathogen, Enterococcus faecalis .
The study highlights the need for C. elegans laboratories worldwide to pay attention to the possible differential impacts of the diet on experimental results, says coauthor and student Ryan Lee.
"Some laboratories use the OP50 as standard food and others use HT115 or even another strain of E. coli ," says Lee. "Our results show that there are significant metabolic differences between these diets, and it is likely that these differences may contribute to substantial uncertainty in research results."
The National Institutes of Health, the Cancer Prevention and Research Institute of Texas (CPRIT), and the Welch Foundation funded the work.
Source: Rice University