http://www.physorg.com/news173950754.html With recent advances in biochemistry, researchers can control the circuitry in a developing cell, thereby influencing cells to develop into specific phenotypes. Taking a step forward in this area, researchers have recently demonstrated a new technique to control gene expression in two dimensions over time, which has not previously been demonstrated. And they have done so using a slightly modified $100 inkjet printer.
Daniel Cohen and Michel Maharbiz of the University of California, Berkeley, along with Roberto Morfino of the École Polytechnique Fédérale de Lausanne in Switzerland, have published their new method in a recent issue of PLoS ONE.
“On an engineering level, we developed an extremely low-cost, user-friendly system that any biology lab can use to explore spatiotemporal control of biological systems,” Cohen told PhysOrg.com. “On a scientific level, we demonstrated that, by controlling the position and timing of chemical dosing in a biological system, we can manipulate arbitrary genetic circuits into behaving like more complex morphogenetic circuits, which are the genetic circuits that regulate pattern formation, such as where our head is relative to our feet and why we have five fingers.”
In their study, the researchers used a commercial-grade Epson R280 inkjet printer to print patterns of lactose and glucose onto an agar gel culture of E. coli in order to regulate the pathway called the lac operon. As the scientists explained, lactose acts as an inducer, while glucose acts as an inhibitor in the bistable lac operon system. The lac system has four states. It can be effectively off if there is no lactose or glucose. If there is glucose but no lactose, the system is also off. If there is glucose and lactose, the system is low-on. If there is lactose and no glucose, the system is full-on. The reason is that glucose provides more energy than lactose so it is better not to waste resources eating lactose if glucose is around.
In their new method, the researchers used a syringe pump to manually inject the lactose and glucose “inks” into the printer’s color reservoirs. The printer functions completely normally, but prints the injected solutions rather than ink. The Epson R280 also has the ability to print on rigid substrates, enabling the researchers to use normal compact discs (CDs) as substrates. Before printing, the scientists first milled 800-micron-deep wells directly into the surface of the CDs, into which they transferred the E. coli cultures. Finally, they used Adobe Photoshop to create specific patterns using the inks, and then to print them directly into the wells.
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