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[SANET-MG] ricin in GM food, feed and fiber
The article below deals with a use of a Ricin gene in GM crops. The
promoters are using the claim that they are developing "sustainable"
The ricin B gene was used (if the ricin AB gene was used it would kill
everybody who used for food or feed). RicinB is a lectin that binds to
sugar residues on the cell surface. RicinB is claimed to be safe for
human consumption but my efforts to find a publication that tested
ricinB fed to humans or animals did not turn up any peer reviewed report
on human or animal testing of ricinB enriched food. It seems ,like Bt
toxin, to be assumed to be safe if not sustainable!
Natural Food Merchandiser
Researchers develop super-toxic Bt genes
In the world of plants genetically engineered to resist insects, up to
90 percent use Bt toxins. That’s why European and African researchers
joined forces to create an über-Bt, one that would work even if insects
developed resistance to Bt toxins. The authors noted that as of yet, no
insect has shown resistance to “traditional” Bt toxins.
The team, led by Paul Christou of the University of Lleida in Spain,
combined Cry toxins (components of Bt toxin) and ricin B-chain proteins
to form BtRB. “Transgenic rice and maize plants engineered to express
the fusion protein were significantly more toxic in insect bioassays
than those containing the Bt gene alone,” the scientists wrote in their
article, appearing in the online early edition this week of the
Proceedings of the National Academy of Sciences.
In fact, after four days, the fusion protein resulted in the deaths of
78 percent of cotton leaf worm larvae that had infested corn plants.
When just one of the proteins was applied, larvae death was less than 20
percent. BtRB was also more toxic toward the stem borer and the
leafhopper, a pest usually unaffected by Bt toxins.
The standard Bt toxin is regularly applied to nonorganic crops of
cotton, corn and potatoes. Cry toxins have not been tested for their
toxicity to mammals, and haven’t yet been used in commercially available
crops. They’re being considered for use in GE rice, though. Ricin, which
is produced naturally by castor beans, can be deadly if inhaled,
injected or ingested, and is often considered an agent of chemical or
biological warfare. It consists of two protein chains, ricin A and ricin
B. Only ricin B was considered for use in transgenic agriculture in this
“If transgenic crops expressing fusion proteins like BtRB were adopted
by farmers, it would be necessary to establish that the insecticidal
activity of the unique toxin retained some specificity, to avoid
deleterious effects on nontarget and beneficial insect species,” the
“Lessons learned after the indiscriminate and irresponsible use of
chemical pesticides for the control of insect pests over the past
several decades call for reason and caution in how we deploy transgenic
plants expressing insecticidal genes in the present and in the future,”
they warned later in the paper.
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