Lord of the Fruit Flies
Fruit flies scrubbed clean of bacteria did not outlive their grubby siblings, the researchers report in the Aug. 8 issue of Cell Metabolism.
The finding challenges the conventional wisdom that even harmless bacteria – and the immune response they provoke – suck up the energy of the host organism and hasten its death.
“It seemed like it was dogma that if the organism has to spend energy doing something, it should shorten the animal’s life,” said co-author and USC College biologist Steven Finkel.
A research team led by John Tower, associate professor of molecular and computational biology at the College, compared normal fruit flies to ones kept in an axenic (bacteria-free) environment.
“The surprise was that the flies grown under axenic conditions and the normal flies had the same life span,” Tower said.
The experiment cannot be replicated in higher organisms, which need bacteria for proper digestion and other functions. But the result in flies still may be relevant to human aging research.
In both flies and humans, the number of bacteria living on the organism increases with age. The innate immune response to bacteria is similar in flies and humans, and it loses strength with age in both species.
The study suggests that all these factors may have nothing to do with aging.
“I think a lot of people would just assume that if you’re increasing bacterial load in an aging human, it must be bad,” Finkel said.
“And it might not just be bad, it just might be. Prior to this study, I would not have thought that.”
The study is part of a broader effort in the Tower lab to eliminate irrelevant factors in aging and close in on its fundamental causes.
“We want to determine what limits the life span of the fly, or any other animal,” Tower said.
Tower’s team eliminated bacteria as a factor by comparing normal fruit flies to specimens born from eggs washed in antibiotic, raised in an axenic environment and given disinfected food throughout their lives. A third group of flies was raised with bacteria and disinfected in adulthood.
Co-author Paul Webster, director of advanced electron microscopy and imaging at the House Ear Institute in Los Angeles, used scanning electron microscopy to visualize structures resembling bacteria biofilms on the surface of older flies.
Tower and co-author Chunli Ren, a graduate student, took bacteria samples from the surface and interior of the flies throughout their life span, confirming that the axenically grown flies were bacteria-free and that bacteria counts in normal flies increased dramatically as the flies got older.
But all the flies lived about as long – approximately three months.
The National Institute on Aging funded the research.
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Los Angeles ran an op-ed by Bill Deverell of the USC College about looking to the past in order to move on to the future. “You can do better, Los Angeles. You’ve heard it before: admonishment from the lecture hall pulpit or the pages of a book or magazine. History matters. You should pay closer attention,” Deverell wrote. “The history of Los Angeles reflects and illuminates American and world history all at once. With a little effort, something powerful happens: historical sensibility provides perspective on the here and now. Who wouldn’t want that?” The column is the first in a series for the magazine’s new CityThink section, L.A. Observed reported.
SoCal Minds featured the USC Good Neighbors Campaign, in which USC faculty and staff donate money for programs benefiting the neighborhoods surrounding the USC campus. The program was launched under the direction of USC President Steven B. Sample in reaction to the Los Angeles riots, the story noted. The campaign raised a record-breaking $1.2 million in donations this past year, despite tough economic times, the article stated. The story reported that several university units had 100 percent participation, including the USC Rossier School, KUSC-FM, the USC Fisher Museum of Art, the Office of the Treasurer, the Office of the Senior Vice President, Administration, the Health Sciences Libraries and USCard Services.
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National Public Radio’s “13.7” ran a commentary by K.C. Cole of the USC Annenberg School about the role of science in diplomacy. “We all know that the technology produced from scientific research can make international conflicts more deadly than ever. But can science help stop war?” Cole said. She mentioned that she recently took part in a USC Center on Public Diplomacy conference on science diplomacy and the prevention of conflict.
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