Local researchers demonstrated their leadership this year in neuroscience, stem cell research, genomics, and astronomy.
Mason Inman
At the end of the brainbow…
Trying to trace out the complex wiring in the brain is enough to give you a headache. So Jeff Lichtman’s lab at Harvard developed a new tool for staining cells a veritable “brainbow” of nearly 100 colors, which could help researchers follow the connections between neurons.
Brain cells light up in a multitude of colors. (Credit: Jean Livet et al.)
Last month, Lichtman and colleagues reported how they engineered mice to carry genes coding for three different colors of fluorescent proteins—yellow, red, and cyan—as well as for an enzyme that blocks the activity of a random subset of these genes. The researchers fed the mice a specific compound to activate the enzyme in neurons; the result was that each neuron generated a different combination of fluorescent proteins, making each one light up with a different hue.
The technique could enable researchers to map out the connections between neurons and shed light on diseases such as autism and schizophrenia that may be caused in part by faulty wiring in the brain’s circuits.
Stem-like cells from skin
The announcement in November that human skin cells could be reprogrammed to act like embryonic stem cells made plenty of headlines. But Rudolf Jaenisch of the Whitehead Institute and Konrad Hochedlinger of Massachusetts General Hospital, along with Japanese researcher Shinya Yamanaka of Kyoto University, paved the way in June when they first showed the trick works in mice (see here and here).
The technique, developed by Yamanaka and colleagues, uses a virus to insert four genes—two of which are known to cause cancer—into skin cells. Once imported, the genes appear to repress activity of the cell’s own versions of these genes, reprogramming the cells so that they are indistinguishable from embryonic stem cells. This could be a strategy for generating large numbers of stem-like cells for research, although the utility of this approach as a therapy—by generating patient-specific cells to replace diseased tissue—remains controversial.
Planetary progress
David Charbonneau of the Harvard-Smithsonian Center for Astrophysics led several studies this year that advanced the field of exoplanet studies—the search for and study of planets outside our solar system.
In May, Charbonneau and colleagues made the first measurements of weather on an exoplanet. They found that the dark side of the planet HD 187733 is surprisingly hot, suggesting that it has supersonic winds ripping through its atmosphere.
In August, Charbonneau and colleagues reported the largest, puffiest planet yet, TrES-4, which has a density close to that of cork. Theorists hadn’t predicted that such planets were possible and they’re still trying to grasp how they hold themselves together. Such findings netted Charbonneau Discover Magazine’s “Scientist of the Year” award.
Cordless recharging for your cell phone
How many times have you rushed out the door in the morning, only to realize you forgot to plug in your cell phone and now it’s out of juice? MIT researchers aim to end this vexing problem with a scheme for sending power through the air—no wires necessary. Last year they theorized that this would work and in June they reported that it actually does.
The physics behind it, known as induction, was discovered in 1831 and is widely used to charge small appliances, such as electric toothbrushes, over distances of just millimeters. The MIT team, led by Marin Soljacić, made induction work efficiently over distances of up to two meters. They came up with conducting coils that transferred electromagnetic waves of a specific frequency to each other, allowing for a more efficient transfer of energy over longer distances. This improvement allowed the researchers to beam power across a room, enough to light a 60-watt bulb.
Svelte spacesuit
As this week’s spacewalks on the International Space Station have shown, astronauts increasingly find themselves outside the comforts of their spacecraft, requiring them to work in bulky suits that restrict their movements.
MIT’s Dava Newman has developed a suit that could make astronaut’s work in outer space a lot easier. In July she unveiled a svelte spacesuit, called the BioSuit, that her team engineered.
This MIT-designed spacesuit could be a lighter and more flexible alternative to today’s bulky gear. (Credit: Donna Coveney, MIT)
Current spacesuits protect astronauts against the low pressure of space by maintaining a layer of high-pressure gas around their bodies. The BioSuit instead uses mechanical pressure, wrapping the body tightly in material. It’s designed to stretch in all the right places—such as the knees and groin—while applying equal pressure across the whole body. This means the suit can be much smaller, lighter, and more flexible, since it dispenses with the gas-pressurization equipment. Although it isn’t ready yet for missions, Newman hopes her suit will be finished in time for the first manned mission to Mars, which NASA is planning for 2018.
68-million-year-old T. rex protein sequenced
In a feat long thought impossible, researchers recovered proteins from a 68-million-year-old Tyrannosaurus rex thighbone and read off their sequence. This showed not only that proteins survive far longer than previously thought, but also provided molecular evidence that the lineages of dinosaurs and birds are closely intertwined.
A team led by John Asara at Harvard Medical School used mass spectrometry to analyze the tiny amounts of surviving protein, broken up into pieces 10 to 20 amino acids long. In April, Asara and colleagues reported that in sequencing the fragments of collagen and piecing the sequences together, they found that the big dino’s collagen most closely resembled that of chickens. Previously, the oldest proteins recovered were between 100,000 and 300,000 years old, and studies had suggested that proteins could survive a million years at most.
RNA interference goes to the head
Small interfering RNAs (siRNAs) show great therapeutic promise since they can shut down genes involved in disease. However, they’re difficult to deliver to the proper cells—and even harder to deliver to brain cells because of the blood-brain barrier. In July, a team led by Premlata Shankar and Manjunath Swamy of Harvard Medical School described a way to get siRNAs past this biological barricade.
The team chemically modified a protein from the rabies virus—which can cross the blood-brain barrier and home in on neurons—to bind it to an siRNA. They injected the RNA-protein package, along with a virus that causes encephalitis, into live mice and showed that the siRNA not only got into the brain but also blocked the expression of crucial genes from this virus in neurons. The researchers say their method could be eventually used to deliver many other kinds of siRNAs or drugs to treat other brain diseases.
Snapshots of malaria in action
Despite decades of study, how the malaria parasite behaves inside humans is still not well understood. But a new technique developed by local researchers captured the first snapshots of the parasite’s gene expression as it infected people.
Last month, Aviv Regev and Jill Mesirov of the Broad Institute, in collaboration with researchers in Senegal, showed how they used computational analysis to tease out patterns of Plasmodium falciparum’s gene expression in the blood of 40 Senegalese malaria patients.
The results revealed a surprising range of parasite behavior not seen in previous studies using cell cultures. It turns out that the parasite tends to take on one of three distinct states while in humans. The first, an active growth state, had already been observed in cell culture. But the researchers discovered a starvation state, in which the parasite resorts to food sources other than glucose, and a stressed state, in which the parasite evinces a reaction similar to heat shock see in lab cultures. Patients with stressed parasites show worse symptoms, with higher body temperatures and more inflammation, the researchers found. The study could help explain why some malaria patients suffer only flu-like symptoms, while others are hit with deadly fevers, and could provide insight when devising new therapies.
HapMap2 shows footprints of natural selection
Combing through millions of small differences among human genomes, Boston-area researchers identified signs of relatively recent natural selection at work. Eric Lander’s group at the Broad Institute sifted through more than three million single-nucleotide polymorphisms, or SNPs—single-letter genomic variations—documented by the International HapMap Consortium in a paper published in October in Nature.
In another paper in the same issue, Pardis Sabeti, a postdoc in Lander’s lab, discussed how she and colleagues analyzed key genetic variations and pinpointed a couple of genes in West Africans that had apparently been selected as a defense against the Lassa virus. Among other adaptations, they also spotted two genes in Europeans, selected for paler skin and lighter hair.
Nanoscale wires harness solar power
Even nano-sized solar cells can soak up light and turn it into electricity, a study in October from Harvard researchers showed.
Charles Lieber’s group reported the first self-contained nanoscale solar cell, a tiny wire built like a coaxial cable, with a conductive inner core, a conductive outer layer, and an insulating layer sandwiched in between. The silicon wire measured just 300 nanometers across. The researchers showed that when hit with light, a single nanowire solar cell could produce a fraction of a nanowatt of power—a small amount, but enough to power a nano-sized circuit. Although it’s unlikely to improve the efficiency of large solar cells any time soon, Lieber says the wire could enable nanodevices to generate their own power.