What’s the News: Scientists have developed the first biological laser, made from a single living cell. This “living laser,” described in a new study in Nature Photonics, could one day lead to better medical imaging and light-based treatments for cancer or other diseases.
Posts Tagged ‘cells’
Researchers Build a Living Laser
“Endosymbiotic” Algae Live Within the Cells of Salamanders
What’s the News: Spotted salamander embryos, a recent study found, have green algae living inside their cells. While scientists have long known that the two species are symbiotic, each helping the other to survive, the new findings show that the arrangement is, in the researchers’ words, “more intimate than previously reported.” In fact, it’s the first such organism-within-cell partnership—known as endosymbiosis—ever observed in vertebrates.
How the Heck:
Special Laser Gives Real-Time View Inside Living Cells for the First Time
From the perspective of a kidney cell, light is a toxic substance: It spends its life hidden under layers of skin and guts, far away from any kind of intense illumination. As a result, biologists using microscopes to study kidney cells and other living cells are always racing the clock—the very light required to see the cell will also kill it. But light toxicity is no longer an issue with the invention of a new microscope that uses focused sheets of light to create 3-D movies of living cells.
The technique is called Bessel beam plane illumination microscopy, and it works by shooting thin planes of light toward the side of a cell, illuminating the specific plane the microscope is focusing on, instead of drowning the entire cell in top-down light.
“We have for the first time a technology that allows you to look at the three-dimensional complexity of what’s going on, at the sort of rates at which things happen within cells,” Dr [Eric] Betzig [the Howard Hughes Medical Institute (HHMI) physicist who led the research] said. [BBC]
Using Tiny Glass Spheres as a Superlens, Microscope Shatters Resolution Record
Modern microscopes opened up the world of the minute to an amazing degree, allowing people to see all the way down to a bacterium wriggling on a slide. But if you want to see down even smaller in regular optical light—to a virus, a cell’s interior, or other objects on the nanoscale—you’ve been out of luck. Those objects are smaller than 200 nanometers, what’s been considered the resolution limit for microscopes scanning in white light, and so the only was to see them was through indirect imaging devices like scanning electron microscopes.
Not anymore. Lin Li and colleagues report a new way using tiny beads to resolve images at 50 nanometers, shattering the limit for what can be seen in optical light.
Their technique, reported in Nature Communications, makes use of “evanescent waves“, emitted very near an object and usually lost altogether. Instead, the beads gather the light and re-focus it, channelling it into a standard microscope. This allowed researchers to see with their own eyes a level of detail that is normally restricted to indirect methods such as atomic force microscopy or scanning electron microscopy. [BBC News]
Those beads are called microspheres—they’re tiny glass balls about the size of red blood cells. The researchers apply these spheres to the surface of the object they want to see. In essence, the spheres capture light that normally would be lost before it ever reached the observer’s eye (those evanescent waves), enabling Li’s team to overcome the diffraction limits of microscope machinery that have limited the maximum possible resolution.
Researchers Push a Blood Test for Cancer Toward the Doctor’s Office
Already, researchers have imagined and built ways to detect one-in-a-billion cancer cells in a person’s bloodstream in order to catch cancer in the act of spreading. Now, that technology is a little closer to moving out of the lab.
Mehmet Toner and colleagues from Massachusetts General Hospital, the brains behind the tech, announced an agreement with a subsidiary of Johnson & Johnson to begin commercial development of their “liquid biopsy.”
The microchip is dotted with tens of thousands of tiny posts covered with antibodies designed to stick to tumor cells. As blood passes over the chip, tumor cells separate from the pack and adhere to the posts. Scientists are wagering that this type of test, if successful, might also detect cancer early in its course, predict the odds for a recurrence, and assess a patient’s general prognosis. [Healthday News]
Toner’s team developed the prototype of the test back in 2007, and for the last several years have refined the extreme sensitivity needed to catch stray cancer cells roaming the bloodstream.
The Peculiar Case of a Postdoc Sabotaging His Colleague’s Cell Cultures
Nobody wants to win more than lab rats—grad students and postdocs thanklessly toiling away at experiments into the night, trying to make a name for themselves. And when a lot of people want something badly, some of them cheat.
A spectacularly gratuitous case came out in Nature this week: that of former University of Michigan postdoc Vipul Bhrigu. After being caught on hidden camera using ethanol to poison the cell cultures of grad student Heather Ames, Bhrigu was sentenced for malicious destruction of personal property. Most people take that particular misdemeanor rap for vandalizing a car. Bhrigu vandalized months of research.
Bhrigu has said on multiple occasions that he was compelled by “internal pressure” and had hoped to slow down Ames’s work. Speaking earlier this month, he was contrite. “It was a complete lack of moral judgement on my part,” he said. [Nature]
A Nano-Wiretap: Scientists Use Nanowires to Spy on a Cell’s Inner Life
Meet the cyborg cell. By attaching probes with nano-hairpin connectors to living cells, researchers have measured electrical currents from inside. They hope the probes will provide a useful way to monitor cells’ health.
A team at Harvard University conducted the study, which appears in Science. Though other probes can measure the currents in electrical impulse-producing cells–such as beating heart cells–none have given researchers the precision of measuring from inside. The probes designed in this study allowed researchers to successfully measure the electric pulses from cultured chicken heart cells’ beating.
One of the team’s challenges was getting the wires to kink into the hairpin shape–a difficult maneuver using traditional nanowire-making techniques. They noted if they stopped the wire as it formed, they could force it to bend.
Newfound Fossils Suggest Multicellular Life Took Hold 2 Billion Years Ago
Is mulitcellular life like us just the new kid on the biological block, a latecomer to a world dominated by single-celled organisms like bacteria? Perhaps not—multicellular life could be nearly half as old as the Earth itself.
A new study out today in Nature identifies fossils from Gabon in Africa that date back 2.1 billion years. The organic material is long gone, but the scientists say these are the oldest multicellular organisms ever found. That date takes them way back before the Cambrian explosion 500 million years ago that made multiple-celled life widespread on the planet.
“We have these macrofossils turning up in a world that was purely microbial,” says Stefan Bengtson, a palaeozoologist at the Swedish Museum of Natural History in Stockholm and a co-author on the report. “That’s a big deal because when you finally get big organisms, it changes the way the biosphere works, as they interact with microbes and each other” [Nature].
A Lesson From the Zebrafish: How to Mend a Broken Heart
When a person has a heart attack, the heart repairs its damaged muscle by forming scar tissue. As a result, the heart never truly goes back to the way it was. But when a zebrafish has a heart injury, like having a large chunk of it chopped off, it grows a brand new piece to replace it.
Two independent reports published in the journal Nature show that within days of an injury to its heart, the zebrafish has the remarkable ability to regenerate most of the missing cardiac tissue using mature heart cells–not stem cells, as some researchers had suspected.
The findings help explain why human beings can’t regenerate a heart or missing limbs. The reports contradict a previous study (pdf) done by one of the research teams in 2006 that suggested that stem cells, the general all-purpose cells that develop into all the mature and functional cells of the body, were responsible for self-repair.
The finding suggest that doctors have been on the wrong track with recent stem cell-based therapies for heart attack patients. Many heart patients have received injections of stem cells, often ones taken from their own bone marrow. But the beneficial effects have generally been unremarkable [The New York Times].
For Sexually Confused Chickens, The Answer Is in Their Cells
The technical way to explain this odd-looking fowl is that it’s “gynandromorphous.” But if you just want to call it “one seriously confused chicken,” that works, too.
For a new study in Nature, Michael Clinton and colleagues investigated a few of these half-male, half-female chickens they obtained from chicken farms. Gynandropmorphs show up now and then not just in chickens, but also in parrots, pigeons, and some other kinds of animals. But scientists weren’t sure how the mix-up happens, since the standard idea for sex differentiation is that the sex hormones released by the gonads either masculinize or feminize the embryo. Clinton’s team discovered that bird cells don’t need to be programmed by hormones. Instead they are inherently male or female, and remain so even if they end up mixed together in the same chicken [BBC News].
The researchers had first assumed that the half-and-half chickens followed the hormone pattern, and that they were females with some sort of chromosomal problem on the male side (the lighter half of the bird in the image, which also sports a large wattle, sturdy breast musculature, and a leg spur on its male side). Instead, they found the chickens to be almost perfectly split between male and female. The hen half was, for the most part, made up of normal female cells with female chromosomes, whereas the cockerel side contained mostly normal male cells with male chromosomes [Nature News].
Researchers Track the HIV Virus to a Hideout in the Bone Marrow
For a study this week in the journal Nature Medicine, Kathleen Collins and her team have uncovered another of HIV’s dirty tricks: the virus can hide out in bone marrow cells and lie in wait for the right time to strike.
In recent years, drugs have reduced AIDS deaths sharply, but patients need to keep taking the medicines for life or the infection comes back, she said. That’s an indication that while the drugs battle the active virus, some of the disease remains hidden away to flare up once the therapy is stopped [AP]. One place the researchers already knew HIV could hide was inside resting T cells. However, Collins says, she thought T cells alone didn’t offer a complete picture of the virus’ ability to play hide-and-seek.
A Biotech Magic Trick: Skin Cells Transformed Directly Into Brain Cells
Cells just keep surprising us. Researchers have now found that, with a little genetic tweaking, they can transform skin cells into brain cells without having to first reprogram them to act like multipurpose stem cells. This finding, the first of its kind, is in this week’s edition of the journal Nature.
The researchers did their study on mice. They induced the change by inserting only three genes into cultured skin cells. Once those three genes activated, the skin cells converted into fully functioning nerve cells that even formed synapse connections with the other converted nerve cells [Popular Science]. That change took less than a week, a surprisingly rapid rate. Said team member Marius Wernig: “These are fully functional neurons. They can do all the principal things that neurons in the brain do” [AFP].
Video: Fluorescent Bacteria Keep Time Like a Clock
One small step for flashing bacteria, one giant leap for synthetic biology. In a new Nature study, molecular biologist Jeff Hasty and his team say they have created a line of E. coli bacteria that flash in fluorescent light and keep time like a clock.
Previously, scientists had engineered only single cells to become oscillators — devices that could count time by performing a particular activity on a cyclical schedule [Nature News]. Back in 2008, Hasty and his team created an oscillator for single cells that could be set to temperature or chemical triggers. But now the researchers have induced a whole host of bacteria to work together to keep time by taking advantage of the way they collaborate naturally: quorom sensing.
