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Jumping genes seen in plant experiment (Friday, Feb. 7, 2003 -- CropChoice news) -- The Australian via Agnet:
Genes in the chloroplast of a genetically-modified plant cell have been
observed jumping into the cell's nucleus for the first time, Australian
scientists have announced.
But the researchers, from the University of Adelaide, said that their study
of tobacco plants did not indicate genetically-modified (GM) crops are less
safe. The work is described in today's issue of the journal Nature.
Led by Associate Professor Jeremy Timmis, the group bred a marker gene into
the plant's chloroplasts, semi-autonomous organelles inside each plant cell
that are chiefly responsible for photosynthesis.
They then looked for signs of the marker gene in 250,000 of the seeds the
plant produced. In about one in every 16,000 seedlings, the marker gene had
done the unexpected - it had moved into the nucleus of the cell, where DNA
is stored and replication controlled.
This means it not only migrated through the cytoplasm of the cell, but
passed through the double membrane wall protecting the nucleus.
Timmis downplayed the implications for GM plants, saying the marker gene
used was specifically chosen for the purpose. And while movement of genes
from chloroplast to nucleus does not occur naturally, there are many more
processes before a complete and functional gene could make the migration.
"We put a new gene in - but made it absolutely ready to be expressed in
nucleus," he told ABC Science Online. "The gene was not expressed at all in
the chloroplast, only if it ended up in the nucleus."
It is possible to differentiate between the two regions as chloroplast genes
are controlled in a completely different way, he said. | |
