The human microbiome is one of the most complex communities of species on the planet. It is the collection of all the microbial organisms in our bodies, the number of which is about 10 times greater than that of our own cells. One day, a better understanding of the human microbiome could allow researchers to manipulate it for the sake of improved health. However, we currently can’t even discern the roles of individuals in a community the fraction of its size.
Together with Karen Nelson, director of the J. Craig Ventor Institute’s genomic medicine group, Epstein was recently awarded a three-year, $1.5 million research project funded by the National Science Foundation to explore the roles of individual organisms in simple model microbial communities located in the High Arctic habitats of Northern Greenland.
“The holy grail in microbial ecology is to figure out the roles of individual microbial species as a community develops,” Epstein said. He explained that scientists are currently able to use genomics to get a genetic picture of an entire community. The results, however, are limited and fragmented because they cannot distinguish one organism’s contribution from another’s.
With their complementary expertise in microbial cultivation and genomics, Epstein and Nelson will characterize the roles of a majority of species in several simple soil communities. First, Epstein’s team will identify the bacterial communities they wish to investigate, and then they will cultivate as many species as possible in the lab.
From there, Nelson’s team will analyze each species for genetic, metabolic and molecular signatures to use as references when they look at the community as a whole.
Ultimately, they will use the collective data to establish computational models that can be used to predict outcomes of various environmental changes. They will then make the same changes in the wild to verify whether the predicted response is in fact observed. If the model is valid, they will look at larger communities, eventually working toward those as complex as the human microbiome.
“If we’re able to increase the abundance of one microorganism that is beneficial, or decrease the abundance of another that is not beneficial,” Epstein said, “this will be a totally different universe.”
If predictive models work with a simple model community, he said, then larger efforts should work on larger communities. He hopes the work will eventually lead to “smarter” infectious disease treatments by targeting specific organisms instead of indiscriminately wiping out entire communities, as is the case with current antibiotics.
“For now we need to show that the concept works in the simple setting,” Epstein said.
A pivotal moment for particle physics
A search that began almost 50 years ago is finally coming to a close. “But this is just the beginning,” said Northeastern physics professor Emanuela Barberis. She and her Northeastern colleagues Darien Wood and George Alverson have been among thousands of physicists in search of the Higgs Boson with the DZero experiment at Fermilab in Illinois and the CMS experiment at CERN in Switzerland. Earlier this week, physicists at CERN announced the most definitive evidence yet.
The so-called “God particle” was first theorized in the 1960s as essential to the Standard Model of particle physics. Without it, our fundamental understanding of the universe would be incorrect and some other explanation would be necessary.
The Standard Model says that fundamental particles in our universe attain mass by passing through a “Higgs field,” which is similar to an electromagnetic field but with one key difference. Instead of generating electromagnetic radiation, a Higgs field generates mass.
“When the field is interacting with itself, you get the Higgs boson,” said Barberis. “If the field is there, you should observe this particle.”
But the Higgs is one of the heaviest fundamental particles around; as such, it is very unstable and readily decays into lighter particles, like electrons, muons and photons. In explaining why it took so long for physicists to finally see evidence of the particle’s existence, Barberis explained that the probability of producing it is very small.
The researchers’ challenge was augmented by the fact that observing the fundamental building blocks of the universe is no easy task. Scientists collide subatomic particles, like protons, into one another at a rate near the speed of light. The resulting debris consists of a mess of elementary particles, each of whose mass is detected and measured against a background of known particle masses. Any unusual signals could be a sign of a previously unobserved particle — like the Higgs.
Because mass can be correlated to energy, higher energy collisions will generate particles of higher mass. Since the 1990s, when the first Higgs search began in earnest, scientists have created colliders of greater and greater energy, ruling out potential Higgs masses and narrowing down the window in which it could be found.
Fermilab’s Tevatron produced collisions with energies up to two teraelectronvolts (or two trillion electronvolts) while CERN’s Large Hadron Collider can currently reach eight teraelectronvolts.
On Monday, Fermilab scientists announced that the Higgs boson would have a mass between 115 and 135 gigaelectronvolts. Then, on Wednesday, CERN’s team enhanced that prediction by presenting spectacular signals of a new particle with a mass around 125 gigalectronvolts. The probability that the CERN signal is a fluke is one in three million. But there’s still a possibility that it is not the Higgs at all.
Going forward, CERN’s Large Hadron Collider will continue colliding protons with one another and sifting through the resulting fragments in an effort to better understand the Higgs and all the other particles we know of — and perhaps some that we don’t.
“This is a pivotal event that will help us shape the future of particle physics research,” said Barberis. “Scientists will now focus on understanding the properties of the observed particle through its interactions with other particles.”