CELL-MEDIATED COMPUTATION SYNTHETIC BIOLOGY: Engineered cells can be combined into complex circuits, researchers show
CIENTISTS HAVE moved a step closer to being
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able to program cells as they would program computers. Two independent groups show it is possible to distribute biological “computations” over multiple cells that perform different logical functions and communicate with one another through signaling molecules that serve as chemical “wires.” The ability to divide computations among different cells means the cells can be used to build circuits analogous to those in electronics. The idea is to be able to harness the power of biology to create sensors and other useful devices. “We’re proposing a very simple circuit to be the building block of constructing programs in bacteria,” says Christopher A. Voigt of the University of California, San Francisco, who led one team. That simple circuit is a NOR gate, which is on only when both of its inputs are off. NOR gates are unusual in that they can be combined to form any of the other gates in Boolean logic. For their NOR gates, Voigt and coworkers use pairs of promoters to control the production of gene repressors (Nature, DOI: 10.1038/nature09565). When both promoters—the gate inputs—are present, the repressor is turned on and the gate does not produce its output (expression of a gene). In the absence of the promoters, the repressor is also inactive and the gene is turned on. The DNA sequences for the promoters, repressors, and genes are incorporated in the bacteria via genetic engineering. Bacteria can be genetically modified so each strain
COATINGS
is a different logic gate. The gates are wired together by chemical signals between cells. The product of one gate diffuses to and becomes one of the inputs for the next gate in the circuit. The spatial arrangement of different strains determines the output of the overall system. In separate work, Ricard Solé, Francesc Posas, and coworkers at Pompeu Fabra University, in Barcelona, show that a small number of different types of cells can be combined to create a large CIRCUIT DIAGRAM number of differCells (spheres) designed to carry out specific ent circuits with logic functions can be “wired” together with different funcsignaling molecules (blue) to carry out complex tions (Nature, functions. The white drawings on the spheres are DOI: 10.1038/ symbols used in electrical circuit diagrams. nature09679). “We can use [cells] in a combinatorial way,” Solé says. “Potentially we can generate thousands of different circuits and so implement thousands of different functions.” The Spanish team engineered yeast cells and combined them in various ways to perform specific logic functions, such as multiplexing and one-bit binary addition with carry. The findings from both teams “represent significant advances in the number and types of logical operations that cell consortia can perform,” says Justin P. Gallivan of Emory University. “Some of the next big challenges include developing more robust networks that can respond to a wider variety of small-molecule inputs and produce more sophisticated output signals.”—CELIA ARNAUD
Arkema will pay $725 million to buy three Total businesses
Specialty chemical maker Arkema will pay more than $725 million to acquire three coatings ingredients businesses from its former parent, the French oil company Total. Arkema was spun out of Total in 2006. When the deal closes in the first half of 2011, “we should become a global leader in the coatings market alongside BASF and Dow Chemical,” says Arkema CEO Thierry Le Hénaff. The acquisition will include 20 sites in 13 countries employing 1,750 people. Sales from the three units will exceed $1.1 billion this
year, Total projects, up 20% from 2009. Included in the sale are resins, emulsions, and rheology additives for coatings, adhesives, and inks. They are sold in Europe, Asia, and South Africa by Cray Valley and in the U.S. by Cook Composites & Polymers. Also included is Sartomer, a maker of ingredients for radiation-curable coatings. Total will retain Cook’s composites resins business and Cray’s hydrocarbon specialties business. “On paper, Arkema and the coatings companies have everything going for
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them since they know each other,” says Phil Phillips, managing director of paint industry experts Chemark Consulting. The acquisition also should allow Arkema to leverage its existing acrylic acid and paint latex assets, Phillips notes. Early this year, the firm bought Dow’s acrylic acid plant in Clear Lake, Texas, and its UCAR latex business in North America. “The three Total businesses will give Arkema additional acrylic systems to compete with Dow and BASF in the marketplace,” Phillips says.—MARC REISCH
RICARD SOLÉ
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