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By Emma Patten-Hitt
NEW YORK (Reuters
Health) - A soil bacterium that causes lumpy tumors on plants
may be able to 'jump kingdoms' and insert its tumor-causing DNA
into human cells, new research findings suggest.
The bacterium,
called Agrobacterium tumefaciens, contains a small piece of DNA
that can insert itself into the DNA of a host cell and initiate
a tumor. Agrobacterium is already known to cause plant tumors,
but researchers wanted to test whether the bacterium could similarly
insert its DNA into human cells.
Dr. Vitaly
Citovsky from the State University of New York, Stony Brook, and
colleagues found that the plant bacterium was able to attach to
human cells and insert its DNA into human cells just as it does
with plant cells.
Whether Agrobacterium
is dangerous to humans is unclear, however. ``Here (insertion
of DNA into) human cells has been observed in laboratory conditions;
whether it may be relevant biologically in nature remains unknown,''
the researchers note in the current early edition of the Proceedings
of the National Academy of Sciences (news - web sites).
``Our experiments
were done under laboratory conditions,'' Citovsky told Reuters
Health. ``In nature, I do not believe Agrobacterium represents
a danger. However, for people who work with large concentrations
of this bacterium, for example researchers or certain agricultural
workers who deal with heavily infected plants, it may be prudent
to be careful or at least aware,'' he said.
One implication
of this study, said Citovsky, is the potential for genetic flow
between bacteria and animals. Another implication is that the
basic biochemical and cellular reactions involved in the Agrobacterium-plant
cell interaction probably exist in the animal kingdom as well.
``Presently,
it appears that Agrobacterium is the only example of trans-kingdom
DNA transfer,'' Citovsky said. ``I do not rule out other possibilities
but there are no data. Of course, what can be done once, can almost
always be done again,'' he added.
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