Researchers turn programmed bacteria into living
computers
LOS ANGELES (Xinhua) -- U.S. researchers
reported on Wednesday they have successfully programmed bacteria to
communicate with each other and produce color-coded patterns, making
living cells function as "tiny computers."
This achievement will finally help manipulate living cells to
detect hazards, build structures or repair tissues and organs within
the body, said researchers at Princeton University. Their work is
published in the April 28 issue of journal Nature.
"We are really moving beyond the ability to program individual
cells to programming a large collection -- millions or billions --
of cells to do interesting things," said Ron Weiss, an assistant
professor at Princeton University who led the study.
The researchers programmed E. coli bacteria to emit red or green
fluorescent light in response to a signal emitted from another set
of E. coli. In one experiment, the cells glowed green when they
sensed a higher concentration of the signal chemical and red when
they sensed a lower concentration.
The bacteria formed a bull's-eye pattern, a green circle inside a
red one surrounding the sender cells, in a Petri dish. This sensing
system could be useful for the detection of chemicals or organisms
in laboratory tests.
"The bull's-eye could tell you this is where the anthrax is,"
Weiss said.
In previous work, Weiss showed the feasibility of inserting
modified pieces of DNA into cells to make them behave in the same
manner as digital circuits. The cells could be made to perform basic
mathematical logic and produce crisp, reliable readouts that are
more commonly associated with silicon chips than biological
organisms.
The new study applied similar techniques to a large population of
cells, showing an integrated package where the cells have an ability
to send messages and other cells have the ability to act on these
messages, according to Weiss.
The creation of patterns, such as the bull's-eye effect, is a key
step to have the cells secrete materials that build physical devices
such as antennas or transmitters in places that are hard for humans
to reach.
Programmed cells also could be used to control the repair or
construction of tissues within the body, possibly guiding stem cells
to the locations where they are needed for the growth of new nerve
or bone cells in a process called "programmed tissue
engineering."
Even the early step of creating patterns in a Petri dish may be
useful as a tool for other scientists, particularly developmental
biologists who are trying to understand how the cells of an embryo
arrange themselves into patterns that become the various body parts
of a mature organism.
In fruit fly embryos, for example, the first cells are thought to
differentiate into the head, abdomen and other parts based on the
concentration of chemical signals that are emitted from the ends of
the embryo.
"Construction and study of such synthetic multicellular systems
can improve our quantitative understanding of naturally occurring
developmental processes and may foster applications in tissue
engineering, biomaterial fabrication and biosensing," the
researchers said in their paper.
Source: Xinhua News Agency - CEIS
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