United States
March 5, 2007
Leafy greens and beans aren't the
only foods that pack a punch of folate, the vitamin essential
for a healthy start to pregnancy.
Researchers now have used genetic engineering--manipulating an
organism's genes--to make tomatoes with a full day's worth of
the nutrient in a single serving. The scientists published their
results in this week's online edition of the journal PNAS,
Proceedings of the National
Academy of Sciences.
"This could potentially be beneficial worldwide," said Andrew
Hanson, a plant biochemist at the University of Florida at
Gainesville who developed the tomato along with colleague Jesse
Gregory. "Now that we've shown it works in tomatoes, we can work
on applying it to cereals and crops for less developed countries
where folate deficiencies are a very serious problem."
Folate is one of the most vital nutrients for the human body's
growth and development, which is why folate-rich diets are
typically suggested for women planning a pregnancy or who are
pregnant. Without it, cell division would not be possible
because the nutrient plays an essential role in both the
production of nucleotides--the building blocks of DNA--and many
other essential metabolic processes.
Deficiencies of the nutrient have been linked to birth defects,
slow growth rates and other developmental problems in children,
as well as numerous health issues in adults, such as anemia.
"Folate deficiency is a major nutritional deficiency, especially
in the developing world," said Parag Chitnis, program director
in the National Science Foundation's
Division of Molecular and Cellular Biosciences, which funded the
research. "This research provides the proof-of-concept for the
natural addition of folate to diet through enhancement of the
folate content of fruits and vegetables."
The vitamin is commonly found in leafy green vegetables like
spinach, but few people eat enough produce to get the suggested
amount of folate. So, in 1998, the Food and Drug Administration
made it mandatory that many grain productssuch as rice, flour
and cornmeal be enriched with a synthetic form of folate known
as folic acid.
Folate deficiencies remain a problem in many underdeveloped
countries, however, where adding folic acid is impractical or
simply too expensive.
"There are even folate deficiency issues in Europe, where
addition of folic acid to foods has not been very widely
practiced," Gregory said. "Theoretically, you could bypass this
whole problem by ensuring that the folate is already present in
the food."
Will doctors be recommending a healthy dose of salsa for
would-be pregnant women anytime soon? Probably not, the
researchers say.
"It can take years to get a genetically-engineered food plant
approved by the FDA," Hanson said. "But before that is even a
question, there are many more studies to be done--including a
better look at how the overall product is affected by this
alteration."
And there is another hurdle the researchers must clear. Boosting
the production of folate in tomatoes involved increasing the
level of another chemical in the plant, pteridine. Little is
known about this chemical, which is found in virtually all
fruits and vegetables.
The National Science Foundation (NSF) is an independent
federal agency that supports fundamental research and education
across all fields of science and engineering, with an annual
budget of $5.58 billion. NSF funds reach all 50 states through
grants to nearly 1,700 universities and institutions. Each year,
NSF receives about 40,000 competitive requests for funding, and
makes nearly 10,000 new funding awards. The NSF also awards over
$400 million in professional and service contracts yearly.
Source:
Agro-Bio Colombia
Tomates transgénicos para cubrir las
necesidades diarias de folatos
Un equipo de científicos de la Universidad de Florida creó
tomates transgénicos que fabrican 25 veces más folato (ácido
fólico o vitamina B9) que los tomates comunes, y podrían ofrecer
hasta siete veces más folato que los vegetales de hojas verdes,
considerados una fuente muy rica de esta vitamina. El ácido
fólico se encuentra principalmente en las verduras de hojas
verdes, además de las lentejas y los garbanzos.
La deficiencia en ácido fólico
durante las primeras etapas del embarazo parece estar asociada
al riesgo de presentar defectos del tubo neural (NTD), conocidos
comúnmente como espina bífida y anencefalia en los bebés. Es por
eso que a partir de 1998 los cereales y sus derivados (harinas)
se fortifican con ácido fólico. "Sin embargo, la fortificación
de los alimentos a veces es difícil de implementar debido a los
costos, principalmente”, explica Rocío Díaz de la Garza, una de
las autoras del trabajo.
"Por eso la biofortificación, es
decir la fortificación a través de la modificación genética de
las vías metabólicas de la planta, es una alternativa muy
interesante para aumentar la cantidad de folato en los
alimentos”. Según lo describen en el último número de la revista
Proceedings of the National Academy of Sciences, los científicos
han logrado por ingeniería genética dos tipos de tomates
transgénicos que producen en gran cantidad al precursor del
folato, el pteridin o p-aminobenzoato - PABA, y cruzando estas
dos líneas obtuvieron plantas de tomate que contienen 25 veces
más folato que los tomates comunes.
Los tomates se obtuvieron por
transformación genética, usando dos genes de la planta modelo
Arabidopsis: el de la enzima aminodeoxicorismato sintasa
(AtADCS) y el de la CTP ciclohidrolasa I (GCHI), ambas
necesarias para la formación del PABA y la hiperacumulación del
folato.
Los tomates que tienen ambos genes
acumulan alrededor de 840 microgramos de folato por cada 100
gramos de fruto, lo suficiente como para cubrir los
requerimientos diarios de una mujer embarazada. “Es menos que
una porción diaria”, señalaron los investigadores. |
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