SHAFAQNA (Shia International News Association) – The transistor revolutionized electronics and computing. Now, researchers have made a biological transistor from DNA that could be used to create living computers.
A transistor is a device that controls the flow of electrons in an electrical circuit, which acts as an on-off switch. Similarly, the biological transistor — termed a transcriptor — controls the flow of an enzyme as it moves along a strand of DNA (deoxyribonucleic acid). These cellular building blocks could be used to do anything from monitoring their environment to turning processes on and off in the cells. The findings were reported Thursday, March 28, in the journal Science.
"Transcriptors are the key component behind amplifying genetic logic," lead author Jerome Bonnet, a bioengineer at Stanford University, said in a statement. On their own, these devices do not represent a computer, but they allow for logical operations, such as "if this-then that" commands, one of three basic functions of computers (the other two being storing and transmitting information).
To make the transcriptors, the researchers took a group of natural proteins, the workhorses of cells, and used them to control how the enzyme known as RNA polymerase zipped along a DNA molecule. The team used these transcriptors to create the mathematical operators that perform computations using Boolean logic.
1s and 0s
Boolean logic, named for the 19th-century mathematician George Boole, refers to a branch of math in which variables can have a true or false value (a 1 or a 0). In a Boolean circuit, the logic gates are like traffic conductors, deciding which of these values gets transmitted. [Album: The World's Most Beautiful Equations]
For example, the "AND" gate takes in two values as input, and only outputs 1 (a true value) if both inputs are 1. An "OR" gate, by contrast, outputs a 1 if either of its inputs is 1. Combining these simple gates in different ways gives rise to even the most complex forms of computing.
The scientists created biological versions of these logic gates, by carefully calibrating the flow of enzymes along the DNA (just like electrons inside a wire). They chose enzymes that would be able to function in bacteria, fungi, plants and animals, so that biological computers might be made with a wide variety of organisms, Bonnet said.
Like the transistor, one main function of the transcriptor is to amplify signals. Just as transistor radios amplify weak radio waves into audible sound, transcriptors can amplify a very small change in the production of an enzyme to produce large changes in the production of other proteins. Amplification allows signals to be carried over large distances, such as between a group of cells.
The new technology offers some electric possibilities: sensing when a cell has been exposed to sugar or caffeine, for example, and storing that information like a value in computer memory. Or telling cells to start or stop dividing depending on stimuli in their environment.
The researchers have made their biological logic gates available to the public to encourage people to use and improve them.-www.shafaqna.com/English
Source: Fox News
SHAFAQNA (Shia International News Association) –Why do we get older? It might seem like a silly question, but scientists have asked it in hopes that they might one day counteract the process.
"The Science of Aging", a new video from online video series AsapSCIENCE, answers the question from a biological perspective.
In the video, AsapSCIENCE masterminds Mitchell Moffit and Gregory Brown detail a key player in the aging process: telomeres. These little sequences of DNA sit at the ends of our chromosomes to protect against chromosomal "fraying" as our cells replicate.
How important are they? "In humans, the thing is that as we mature, our telomeres slowly wear down. So the question has always been: did that matter? Well, more and more, it seems like it matters," Dr. Elizabeth H. Blackburn, who won the 2009 Nobel Prize in Physiology or Medicine for her studies on cell biology, told the The New York Times.
Learn more about telomeres and other biological factors of aging in the video above.-www.shfaqna.com/English
SHAFAQNA (Shia International News Association) – Scientists may be a step closer to cracking one of the world’s most compelling mysteries: the impossible complexity of the brain and its billions of neurons. Cornell researchers have demonstrated a new way of taking high-resolution, three-dimensional images of the brain’s inner workings through a three-fold improvement in the depth limits of multiphoton microscopy, a fluorescence-based imaging technique with Cornell roots.
Publishing Photonics Jan. 20, senior author Chris Xu, associate professor of applied and engineering physics, and colleagues have demonstrated high-resolution, 3-D imaging of the subcortical region of a live, intact mouse brain.
They have broken the fundamental depth limit of standard two-photon microscopy, which is a widely used imaging technology invented in 1990 by Watt Webb and Winfried Denk at Cornell. Xu and Webb demonstrated three-photon fluorescence imaging while Xu was a graduate student in Webb’s lab in 1995, but its advantages were not fully recognized then, Xu said.
The new paper describes three-photon fluorescence, combined with a longer excitation wavelength of the laser pulse, to overcome such obstacles as tissue scattering and absorption, which prohibit high-resolution imaging deep within biological tissues. The new paper shows that three-photon microscopy is a much better technology in the context of deep tissue imaging, making multiphoton fluorescence microscopy truly "multiphoton."
Using a mouse model, the researchers have proved the principle of three-photon microscopy operating at a wavelength of 1,700 nanometers. This, in combination with the new laser specifically created for three-photon excitation, allows the researchers to perform high-resolution imaging of neurons at unprecedented depths within a mouse brain.
Pushing these depth limits is important for basic science and eventually could prove useful clinically, Xu said. Depression and diseases like Parkinson’s and Alzheimer’s are associated with changes deep inside the brain, and finding the cures could be helped by subcortical neural imaging -- that is, below the gray matter of the brain and into the white matter and beyond, if the brain is visualized as stacked layers.
"Brain mapping could be the so-called grand challenge within the next decade," Xu said. "With MRI, we can see the whole brain but not with the resolution we have demonstrated. The optical resolution is about 100 to 1,000 times higher and allows us to clearly visualize individual neurons."
In the mouse model, the researchers used dyes and transgenic mice to test their multiphoton microscope on different fluorescent signals and prove their concept. If three-photon microscopy can be used to map the entire mouse brain, it could ultimately help shed light on the functions of human brains and pave the way to breakthroughs in neuroscience and other clinically relevant areas, Xu said.
The paper’s first authors are graduate students Nicholas Horton and Demirhan Kobat and research associate Ke Wang, and includes contributions from the labs of Frank Wise, professor of applied and engineering physics, who helped with the laser optics; and Chris Schaffer, associate professor of biomedical engineering, who taught the applied physicists how to do in vivo mouse brain imaging.-www.shfaqna.com/English
Source: My Science
SHAFAQNA (Shia international Association) — Scientists have discovered a biological switch in blue-green algae that reacts to light and changes how electrons are transported within the cells. The new findings could help in engineering algae for improved biofuel production. The results of the research were published on July 10, 2012 in Proceedings of the National Academy of Sciences.
Blue-green algae, also known as cyanobacteria, are well known for their explosive growth when given the right combination of light, nutrients and warm water. Due in part to their high growth rate, their ability to use wastewater as a source for nutrients and their ability to grow without competing with arable land used to grow food, cyanobacteria and other types of algae have become a prime target for biofuel production.
Lack of light is often a major constraint in algae biofuel production systems because algae need light to photosynthesize. Attempts to increase the amount of light delivered to algae in bioreactors typically involve the use of energy-demanding mixing systems or smaller and more expensive growth chambers.
Alternatively, scientists could try to improve the way that algae grow under low light conditions. But first, they need to more fully understand how the biological molecules within cells respond to light.
To examine how cyanobacterial cells respond to light, scientists attached a green fluorescent protein tag to two key respiratory complexes in the species Synechococcus elongatus. Then, they exposed the cyanobacterial cells to either low light or moderate light conditions in the laboratory and tracked changes in the cells by viewing the cells under a microscope.
The scientists discovered that brighter light caused the respiratory complexes to redistribute throughout the cells from discrete patches into more evenly distributed locations. The redistribution of respiratory complexes appeared to be triggered by changes in the redox state of an electron carrier close to plastiquinone, and resulted in a major increase in the probability that electrons would be transferred to photosystem I, an integral component of the photosynthetic complex shown in the diagram below.
The research was carried out by seven scientists from Queen Mary, University of London, the Imperial College London and the University College London.
Conrad Mullineaux, who is a Professor of Microbiology at Queen Mary, University of London and co-author of the new paper, commented on the findings in a press release. He said:
Any organism that breathes or photosynthesizes depends on tiny electrical circuits operating within biological membranes. We are trying to find out what controls these circuits: what makes the electrons take the routes that they do, and what switches are available to send the electrons to other destinations?
He commented on the new findings further in an interview with Ecoimagination:
It’s rather like a familiar electrical switch. You press on it to change the position of the wires, and thereby change what the electrons do. At this state, we’re just trying to understand what’s happening in the cell. But the potential is there to exploit the knowledge for biofuel production.
Bottom line: Scientists have discovered a biological switch in cyanobacteria that reacts to light and changes how electrons are transported within the cells. The new findings could help in engineering blue-green algae for improved biofuel production. The results of the research were published on July 10, 2012 in Proceedings of the National Academy of Sciences.—www.shafaqna.com/english