Wednesday, October 08, 2003
Nature-nurture revisited!
A Pregnant Mother's Diet May Turn the Genes Around
"Methylation is nature's way of allowing environmental
factors to tweak gene expression without making permanent
mutations, Dr. Jirtle said.
Fleeting exposure to anything that influences methylation
patterns during development can change the animal or person
for a lifetime. Methyl groups are entirely derived from the
foods people eat. And the effect may be good or bad.
Maternal diet during pregnancy is consequently very
important, but in ways that are not yet fully understood.
For his experiment, Dr. Jirtle chose a mouse that happens
to have a transposon right next to the gene that codes for
coat color. The transposon induces the gene to overproduce
a protein that turns the mice pure yellow or mottled yellow
and brown. The protein also blocks a feeding control center
in the brain. Yellow mice therefore overeat and tend to
develop diabetes and cancer.
To see if extra methylation would affect the mice, the
researchers fed the animals a rich supply of methyl groups
in supplements of vitamin B12, folic acid, choline and
betaine from sugar beets just before they got pregnant and
through the time of weaning their pups. The methyl groups
silenced the transposon, Dr. Jirtle said, which in turn
affected the adjacent coat color gene. The babies, born a
normal brownish color, had an inherited predisposition to
obesity, diabetes and cancer negated by maternal diet.
Unfortunately the scientists do not know which nutrient or
combination of nutrients silence the genes, but noted that
it did not take much. The animals were fed only three times
as much of the supplements as found in a normal diet.
"If you looked at the mouse as a black box, you could say
that adding these methyl-rich supplements to our diets
might reduce our risk of obesity and cancer," Dr. Jirtle
said. But, he added, there is strong reason for caution.
The positions of transposons in the human genome are
completely different from the mouse pattern. Good maps of
transposons in the human genome need to be made, he said.
For that reason, it may be time to reassess the way the
American diet is fortified with supplements,.."
A Pregnant Mother's Diet May Turn the Genes Around
"Methylation is nature's way of allowing environmental
factors to tweak gene expression without making permanent
mutations, Dr. Jirtle said.
Fleeting exposure to anything that influences methylation
patterns during development can change the animal or person
for a lifetime. Methyl groups are entirely derived from the
foods people eat. And the effect may be good or bad.
Maternal diet during pregnancy is consequently very
important, but in ways that are not yet fully understood.
For his experiment, Dr. Jirtle chose a mouse that happens
to have a transposon right next to the gene that codes for
coat color. The transposon induces the gene to overproduce
a protein that turns the mice pure yellow or mottled yellow
and brown. The protein also blocks a feeding control center
in the brain. Yellow mice therefore overeat and tend to
develop diabetes and cancer.
To see if extra methylation would affect the mice, the
researchers fed the animals a rich supply of methyl groups
in supplements of vitamin B12, folic acid, choline and
betaine from sugar beets just before they got pregnant and
through the time of weaning their pups. The methyl groups
silenced the transposon, Dr. Jirtle said, which in turn
affected the adjacent coat color gene. The babies, born a
normal brownish color, had an inherited predisposition to
obesity, diabetes and cancer negated by maternal diet.
Unfortunately the scientists do not know which nutrient or
combination of nutrients silence the genes, but noted that
it did not take much. The animals were fed only three times
as much of the supplements as found in a normal diet.
"If you looked at the mouse as a black box, you could say
that adding these methyl-rich supplements to our diets
might reduce our risk of obesity and cancer," Dr. Jirtle
said. But, he added, there is strong reason for caution.
The positions of transposons in the human genome are
completely different from the mouse pattern. Good maps of
transposons in the human genome need to be made, he said.
For that reason, it may be time to reassess the way the
American diet is fortified with supplements,.."
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