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Gizmorama - June 8, 2016

Good Morning,

MIT researchers have conceived a technique for creating cellular gene circuits capable of complex computation. I have no idea what any of that means, but it gets my science-sense tingling.

Learn about this and more interesting stories from the scientific community in today's issue.

Until Next Time,

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* Scientists build gene circuits capable of complex computation *

BOSTON - Until now, synthetic biological systems have focused exclusively on either analog or digital computation. Researchers at MIT have devised a technique for creating cellular gene circuits capable of complex computation.

Analog computation, also called continuous computation, is the type of processing happening as the human eye adjusts to changing light conditions. Digital computation involves binary decision making, on or off processes.

The new synthetic cellular circuitry designed by MIT scientists performs like a comparator, receiving analog input signals and converting them into digital output signals.

In this instance, the circuitry is designed to gauge the level of a chemical -- a potential signature of disease -- and should the level reach a threshold, the circuitry releases a dose of the relevant drug.

"Digital is basically a way of computing in which you get intelligence out of very simple parts, because each part only does a very simple thing, but when you put them all together you get something that is very smart," lead researcher Timothy Lu, an associate professor of biological engineering and head of the Synthetic Biology Group at MIT's Research Laboratory of Electronics, said in a news release.

"But that requires you to be able to put many of these parts together, and the challenge in biology, at least currently, is that you can't assemble billions of transistors like you can on a piece of silicon," Lu added.

The gene circuit features a threshold module capable of analog computation -- sensing the level of a specific chemical. The module is linked to a recombinase gene, which can turn a specific DNA segment on or off by inverting it. The gene segment can be designed to control a specific gene expression, thus, enabling a digital out -- in this case, the release of a drug.

"So this is how we take an analogue input, such as a concentration of a chemical, and convert it into a 0 or 1 signal," Lu explained. "And once that is done, and you have a piece of DNA that can be flipped upside down, then you can put together any of those pieces of DNA to perform digital computing."

Lu and his research partner, former microbiology PhD student Jacob Rubens, designed a circuit that linked both a lower and upper analog threshold to digital outputs. The circuit was capable of measuring glucose and releasing a different drug if levels got too high or too low.

The new research was published in the journal Nature Communications.

* New photonic sensor paves way for high-speed biodetection *

CHAMPAIGN, Ill. - Scientists at the University of Illinois have developed a highly sensitive photonic sensor -- a device they hope will enable new high-speed diagnostic technologies.

Researchers have previously identified links between various diseases, such as cancers and anemia, and mechanical properties of infected cells -- properties like compressibility and viscoelasticity. Currently, there aren't diagnostic tools sufficiently fast or sensitive to detect these properties.

"Because of this, we have a substantial knowledge-gap, and have barely scratched the surface of understanding of how diseases modify the mechanical properties of cells in our body," Gaurav Bahl, an assistant professor of mechanical science and engineering at Illinois, explained in a news release. "Developing knowledge around the mechanics of cells and bioparticles can help us understand the mobility of these micro-objects throughout the human body, about how tumors form, about how cells and bacteria can propagate through us, how diseases spread, and more."

Researchers designed their breakthrough sensor by combining two optical sensing technologies, flow cytometry and mechanical sensing.

"We have developed a new microfluidic opto-mechanical device that optically detects the mechanical perturbations created by individual microparticles flowing through the fluidic channel at very high speed," said Kewen Han, a doctoral candidate at Illinois.

Han is the first author of a new paper describing the breakthrough, published in the latest edition of the journal Optica.

Bahl, Han and their colleagues successfully tested the opto-mechano-fluidic resonator, measuring the density and compressibility of particles as small as 660 nanometers as they whizzed by the sensor.


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