
Top Stories 
Published On May 3, 2012
CLINICAL RESEARCH
Our Germs, Ourselves
The bacteria inside us may form a symbiotic relationship that not only affects metabolism, but emotions and brain development as well.
Among the trillions of bacteria that populate us, most reside in the gastrointestinal system, where their species number in the thousands. But the variation in the number of species between individuals is so great that scientists were beginning to despair of ever detecting a significant pattern to the diversity. Then a study published in May 2011 found that gut flora cluster into three basic patterns of species—a finding that surprised researchers within MetaHIT, the European project cataloguing and analyzing bacteria in the human intestinal tract. It’s one more example of evidence turned up in the past year of these bacteria’s close intertwining with our physiology, a line of research Proto explored in its infancy (“Our Native Flora,”Summer 2010). Resident microbes help extract energy from food, stimulate the immune system and provide a buffer against invading pathogens, among other important tasks. Only recently have scientists managed to link imbalances in our microbial makeup to cancer, inflammatory bowel disease and obesity.
Each of the three “enterotypes”—named Bacteroides,Prevotella and Ruminococcus after their most abundant species—produced different vitamins and processed energy differently. Already scientists are attempting to correlate the enterotypes to diet and other factors. Gary Wu, a gastroenterologist at the Perelman School of Medicine at the University of Pennsylvania, and his team sampled the gut flora of people who had provided long-term dietary information, finding that the Bacteroides enterotype was correlated with animal protein and saturated fat intake, whereas Prevotella was associated with carbohydrate-rich diets. Researchers are now working with human gut bacterial species and so-called germ-free mice—mice with no flora of their own—to see what happens to these bacterial communities as the mice consume diets with varying amounts of protein, starch, sugar and fat.
Yet since Proto reported on the microbiome, researchers have begun to move beyond the connections between gut flora and metabolism to look at how our microbes might interact with our brains. The early evidence suggests that they exert a powerful influence on a mouse’s emotional state and its brain development. Rochellys Diaz Heijtz and her colleagues at the Karolinska Institute in Stockholm discovered that germ-free mice grow up more active and exploratory than those with an intact microbiome, who are more cautious and anxious. It remains to be seen whether the same effect occurs in humans—and just what else the microbes that outnumber our own cells 10 to 1 are doing to us.
Dispatches

What Makes a Kid Clumsy? More research into coordination disorders shows why some children are more prone to trip, fumble and spill the milk.

Eyes in the Sky Satellite data can be used to assess the health impact of dust storms and the spread of mosquito-borne diseases. Additional applications could be on the horizon.

Could This One Change Help Curb the Opioid Crisis? To prescribe an effective bridge to addiction treatment, emergency physicians must get special training and receive a waiver. Making that process easier—or eliminating the requirement altogether—could make a big impact.

One Thing Leads to the Next Robert Lefkowitz is best known for revealing the mechanism behind hundreds of drugs in use today. But he thinks of himself as a storyteller first and has a new book out to make his case.

Podcast: The Research Year That Was Medical research labs have faced a difficult stretch of closed buildings and competing priorities. Yet they have also produced milestone discoveries—and not only on COVID-19.

The Shape of Us Two milestone discoveries in protein modeling promise to change the fundamentals of drug discovery.

Universal Flu Vaccines Move Forward In the shadow of coronavirus vaccine development, another vaccine was making solid progress.

Top Stories 

The Neuroscience of Giving Up
Why do some people react poorly, even catastrophically, in emergency situations?