Posts Tagged ‘cells’
Proton Transistor Could Help Machines and Organisms Communicate
Proton transport is important for several biological processes, notably mitochondrial respiration, and living organisms’ electrical signals are modulated using protonic and ionic currents. So a machine that could mimic this type of information transfer could be used, for example, to monitor biological processes. Someday it could even be used to integrate new devices, like prosthetics, or to control biological systems — say, opening ion channels within cells to allow drugs to pass through.
We’ve seen other systems designed to do this, like synaptic transistors, , and nanoscale devices that use proton-conductive proteins. But those are difficult to build, say Chao Zhong and colleagues at the University of Washington, writing in the journal . It would be useful to have a device based on the type of transistors we all know so well, simply using a different type of current.
In a first step toward functional protonics, Zhong and colleagues built a protonic field-effect transistor. It works exactly like an FET in an electronic system — it has a terminal, a gate and a drain, and it can send pulses of current. The device is partly made from a compound called chitosan, extracted from squid. It can be recycled from crab shells and squid pen discarded by the food industry, according to a . It is biodegradable, biocompatible and non-toxic, the researchers say. The chitosan absorbs water and forms hydrogen bonds, and protons that are dissociated from maleic acids move along this hydrogen-doped channel.
The main drawback for now is that this FET also uses silicon, so it couldn’t be used in the human body; its main use would likely be direct sensing of cells in a lab. But a biocompatible version using some other type of semiconductor could conceivably be implanted in a living organism, monitoring proton activity and sending it to a protonic — not an electronic — device.
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Researchers Capture "Natural Killer" White Blood Cells in Action in Highest Resolution Ever
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There are myriad difficulties in trying to observe this kind of event. For one thing, the cells are incredibly small, and execute their, well, executions (that's an apt description, as you'll see) very, very quickly. Then there's the problem that the cells are three-dimensional (of course), while the high-speed microscopes used for this are only capable of seeing the horizontal plane. (3-D cameras are not, at the moment, quick enough to work for this.) Previously, researchers would have to painstakingly capture many 2-D images, then stack them on top of each other--not very efficient, and not particularly effective, either.
So how did these researchers pull it off? Says Professor Paul French of Imperial College London: "Using laser tweezers to manipulate the interface between live cells into a horizontal orientation means our microscope can take many images of the cell contact interface in rapid succession. This has provided an unprecedented means to directly see dynamic molecular processes that go on between live cells." But taking lots of images at once, the researchers can reconstruct a 3-D image with ease.
What's going on in that video above is essentially an execution. Inside the "natural killer" or "NK" cell, enzyme-filled granules organize, ready to stream out as soon as the cell creates a portal. Then, the granules attack the diseased cell. In this case, the NKs are using membrane nanotubes to pull them in, like a bungee cord.
NKs are used by the body to attack all kinds of damaged cells, from tumors to viruses, though they also sometimes attack transplanted organs. By understanding the intricacies of this operation, the scientists hope to create better medical treatments--they might use NK cells in medicine, or discover ways to stop them from attacking foreign but welcome tissue.
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Scottish Scientists Are Trying to Create Inorganic Life
This research is part of Cronin's larger project to show that inorganic compounds are able to self-replicate and evolve like biological cells do. The ultimate goal is to give these inorganic cells life-like properties so they can evolve and eventually be used in materials science.
Cronin said he believes creating inorganic life is entirely possible, that if biological organisms evolved from single-cell bacteria, so should life be able to evolve from inorganic microorganisms. This “inorganic living technology,” if it works, could change the way we think about evolution, showing that it's not a process exclusive to biology, and that non-carbon-based life could exist.
[BBC]
Quantum Dot Thermometers Take the Temperature of Individual Living Cells
Scientists know plenty about what happens inside a living cell, from the chemical reactions to the physical changes that take place, but information about cell temperature has been sorely lacking. This is a curious problem, because temperature is one of the most important physical factors involved in a chemical reaction, explains Haw Yang, a researcher at Princeton University. Understanding temperature variations could go a long way toward illuminating cellular action, protein use, even diseases.
A myriad of chemical reactions take place inside every cell, and some of those transactions produce excess energy. Active cells may discharge some of this energy as heat, Yang and colleagues say. Other cells may have warmer regions, where mitochondria — cell power plants — are busy producing energy.
So it makes sense that cells would have variable temperatures, but researchers have not been able to measure this. To do it, Yang and Liwei Lin at the University of California-Berkeley used nanoscale thermometers, in the form of quantum dots. The dots are wee semiconductor crystals that change color as temperature changes, Yang explains in a news release from the . The dots, in this case made of cadmium and selenium, emit different wavelengths of light depending on the temperature.
They inserted the dots into some mouse cells growing in lab dishes, and found the cells’ temperatures were different in some regions. Yang and colleagues stimulated cellular activity to watch the changes, and reported a difference of a few degrees Fahrenheit — a pretty big difference. They don’t have enough data to give an exact number, however.
The temperature changes could have major impacts on how cells work and survive, Yang says. Increases in temperature could affect how genes work, for instance, and how protein is manufactured and used. Beyond that, temperature differences could even serve as some form of intercellular communications system, Yang says. The team is now trying to figure out how cellular temperature is regulated.
The research was presented at the American Chemical Society’s annual meeting, in Denver this year.
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New Drug Can Treat Almost Any Viral Infection By Killing the Body’s Infected Cells
Viruses work by inserting themselves into a cell and hijacking its machinery for its own use. The invaded cell then creates more copies of the virus, which involves creating long strings of double-stranded RNA — which contains the virus’ genetic material, like DNA contains ours.
When the virus is done copying itself, its hostage cell usually dies, from the virus bursting through its walls (lysis), changes to the cell’s outer membrane, and from apoptosis, or programmed cell death.
Human cells have plenty of defenses against viral invasion, including proteins that attach to the double-stranded RNA, preventing the virus from replicating itself after successful invasion.
This new drug therapy combines those dsRNA proteins with a protein that induces apoptosis. It’s called a DRACO, Double-stranded RNA Activated Caspase Oligomerizer.
When one end of the DRACO binds to dsRNA, it signals the other end of the DRACO to induce cell suicide, an explains. In this way, the cell is killed before the virus can take over and eventually kill it anyway. If there is no dsRNA, the healthy cells are left alone.
“In theory, it should work against all viruses,” said Todd Rider, a senior staff scientist at MIT’s Lincoln Laboratory who invented the new technology.
A handful of drugs can target specific viruses by interfering with their replication process, through addition of modified DNA building blocks or the blocking of enzymes the viruses need to stimulate the replication process. But viruses are wily bugs, and they can evolve to resist these treatments.
The DRACO therapy could be effective because it targets the host cell, not just the virus.
Rider and colleagues are testing DRACO against more viruses in mice, according to MIT. Rider hopes to license the technology for trials in larger animals and for eventual human clinical trials, too.
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Newly Found Filaments Inside Cells Might Be the Key to How They Divide
The scientists used that data to create a 3-D image of the intercellular bridge, the region where cells split in two. The image showed the cell’s internal skeleton, which includes microtubules [red], and also revealed previously unknown filaments [green] constricting the area where division occurs. Gerlich says that his next goal is to clarify the chemical composition of the mysterious filaments and the process by which they form.
Using Human Cells and Jellyfish Protein, Researchers Build the First Living Laser
A bright future for internal medicine
A single human cell engineered to express green fluorescent protein can be used to amplify photons into super-short pulses of laser light, the researchers say.
Lasers consist of a gain medium, the source of optical gain within the laser which absorbs external energy and excites atoms or molecules into a more energized state, inside an optical cavity. Most lasers use semiconductors, crystals or gases as a gain medium. In this case, the researchers used green fluorescent protein (GFP).
First, the researchers filled an inch-long cylinder with a GFP solution, and placed mirrors at each end. They pulsed it with light and confirmed the GFP solution could amplify the input energy into short pulses of laser emissions, according to a from Mass. General. This proved GFP could serve as the laser’s gain medium. Green fluorescent protein, isolated from jellyfish, will emit green light when it is exposed to blue light.
Then the team engineered human embryonic kidney cells to produce GFP, and placed a single cell between two mirrors, just 20 micrometers apart. The researchers flooded the cell with blue light, and the cell lit up. The mirrors served as the optical cavity, allowing light to bounce through the cell many times, amplifying it into a coherent green beam that was visible to the naked eye.
The cell’s spherical shape acted as a lens, refocusing the light and therefore requiring less energy for lasing than was necessary in the cylinder experiment. Best of all, the cells survived the lasing process, and were able to produce hundreds of pulses of laser light.
A living laser could have a wide range of medical uses, according to lead author Malte Gather at the Wellman Center for Photomedicine at Mass. General. They could be used to activate drugs using light, for instance, or for new forms of imaging — it is difficult for visible and UV light to penetrate very far inside the body. Eventually, living lasers could enable optical communications and computing inside the body, using living systems instead of electronics.
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