|
Negative effects of plastic's additive blocked by nutrient supplements
July 31, 2007DURHAM, N.C. -- Experiments in animals have provided additional and tantalizing evidence that what a pregnant mother eats can make her offspring more susceptible to disease later in life.
This susceptibility is the result of a process that alters how a gene is expressed without actually changing or mutating the gene itself. Appreciation of this phenomenon has spawned a new avenue of genetic research known as epigenetics, a name which refers to changes happening over and above the gene sequence without altering its code.
In their most recent experiments, Duke University Medical Center investigators demonstrated that exposure within the womb to bisphenol A (BPA), an ubiquitous chemical used in the production of plastics, caused noticeable changes in the offspring without altering any of the offspring's genes. Additionally, the researchers discovered that administration of folic acid or genistein, an active ingredient in soy, during pregnancy protected the offspring from the negative effects of BPA.
The results of the study, which was supported by the National Institutes of Health and the Department of Energy, were published early online by the Proceedings of the National Academy of Science July 30.
In their experiments, the Duke team studied a well-documented strain of animals known as agouti mice. Normally, these mice tend to be slender and brown. While past epigenetic research at Duke has focused on nutrients given to pregnant agouti mice, the current experiments represented the first tests of a potential environmental toxin.
The researchers found that when the mouse mothers received BPA, a statistically significant increase in the number of their offspring were born with a yellow coat. Previous studies with these mice have shown that yellow agouti mice are at a much greater risk for diabetes, obesity and cancer.
"The fact that the mice fed BPA had a yellow coat and likely would grow to be obese as adults demonstrates that this single substance had a system-wide effect," said Dana Dolinoy, Ph.D., postdoctoral fellow in the laboratory of Randy Jirtle, Ph.D., senior member of the research team. "A comparison between the large yellow mice and the normal brown mice showed identical genetic makeup, yet strikingly different appearances.
"Just as importantly, when pregnant mothers were also given folic acid or genistein, the epigenetic influence of BPA was counteracted," she added.
BPA is a synthetic estrogen first synthesized in the 1890s and is used in the manufacturing process from such everyday products as plastic water bottles, food containers and baby bottles. While laboratory studies have uncovered possible health concerns in animals, there has been considerable debate in the United States and Europe about what levels are considered safe for human consumption. Attempts have been made in Canada, California, Maryland and Minnesota to ban its use.
Jirtle, one of the leaders of epigenetics research, said that it is difficult at this point to determine what the levels of maternal BPA in humans would equal those that caused epigenetic changes seen in the mice. The levels of BPA used in the current experiments were five times lower than that considered harmful for mice, showing that even a low exposure was able to cause noticeable effects in the offspring.
"Since BPA can be detected at some level in almost all humans, the current findings could hold the promise of reducing disease susceptibility by using nutritional approaches," Jirtle said. "The ability of some agents to counteract the epigenetic effects of a toxin, in this case BPA, with maternal supplements has the potential to protect present and future generations."
Genistein, which is readily available in health food stores, is an active ingredient in soy. It is possible, Jirtle said, that the reason Asians have much lower rates of obesity and certain cancers is that their diet typically includes greater use of soy products than Western diets. However, he pointed out, it is not known at what doses genistein would be protective or harmful in humans. Future studies would be needed to determine optimal doses.
"It's like the findings that have suggested that one glass of red wine a day may be good for your cardiovascular system," Jirtle said. "That may be true, but we certainly know a gallon of red wine a day is not good for you."
Duke University Medical Center
The results of the study, which was supported by the National Institutes of Health and the Department of Energy, were published early online by the Proceedings of the National Academy of Science July 30.
In their experiments, the Duke team studied a well-documented strain of animals known as agouti mice. Normally, these mice tend to be slender and brown. While past epigenetic research at Duke has focused on nutrients given to pregnant agouti mice, the current experiments represented the first tests of a potential environmental toxin.
The researchers found that when the mouse mothers received BPA, a statistically significant increase in the number of their offspring were born with a yellow coat. Previous studies with these mice have shown that yellow agouti mice are at a much greater risk for diabetes, obesity and cancer.
"The fact that the mice fed BPA had a yellow coat and likely would grow to be obese as adults demonstrates that this single substance had a system-wide effect," said Dana Dolinoy, Ph.D., postdoctoral fellow in the laboratory of Randy Jirtle, Ph.D., senior member of the research team. "A comparison between the large yellow mice and the normal brown mice showed identical genetic makeup, yet strikingly different appearances.
"Just as importantly, when pregnant mothers were also given folic acid or genistein, the epigenetic influence of BPA was counteracted," she added.
BPA is a synthetic estrogen first synthesized in the 1890s and is used in the manufacturing process from such everyday products as plastic water bottles, food containers and baby bottles. While laboratory studies have uncovered possible health concerns in animals, there has been considerable debate in the United States and Europe about what levels are considered safe for human consumption. Attempts have been made in Canada, California, Maryland and Minnesota to ban its use.
Jirtle, one of the leaders of epigenetics research, said that it is difficult at this point to determine what the levels of maternal BPA in humans would equal those that caused epigenetic changes seen in the mice. The levels of BPA used in the current experiments were five times lower than that considered harmful for mice, showing that even a low exposure was able to cause noticeable effects in the offspring.
"Since BPA can be detected at some level in almost all humans, the current findings could hold the promise of reducing disease susceptibility by using nutritional approaches," Jirtle said. "The ability of some agents to counteract the epigenetic effects of a toxin, in this case BPA, with maternal supplements has the potential to protect present and future generations."
Genistein, which is readily available in health food stores, is an active ingredient in soy. It is possible, Jirtle said, that the reason Asians have much lower rates of obesity and certain cancers is that their diet typically includes greater use of soy products than Western diets. However, he pointed out, it is not known at what doses genistein would be protective or harmful in humans. Future studies would be needed to determine optimal doses.
"It's like the findings that have suggested that one glass of red wine a day may be good for your cardiovascular system," Jirtle said. "That may be true, but we certainly know a gallon of red wine a day is not good for you."
Duke University Medical Center
Epigenetics News and Current Epigenetics Events RSSOur genome changes over lifetime, Johns Hopkins experts say
Researchers at Johns Hopkins have found that epigenetic marks on DNA-chemical marks other than the DNA sequence-do indeed change over a person's lifetime, and that the degree of change is similar among family members.
Child abuse may 'mark' genes in the brains of suicide victims
A team of McGill University scientists has discovered important differences between the brains of suicide victims and so-called normal brains. Although the genetic sequence was identical in the suicide and non-suicide brains, there were differences in their epigenetic marking - a chemical coating influenced by environmental factors.
'Destruct' triggers may be jammed in tumor cells, UF geneticists say
Tumor cells living in the cross hairs of radiation or chemotherapy may be able to escape death because their self-destruct mechanisms are jammed, say University of Florida scientists writing in a recent issue of Developmental Cell.
Epigenetic research uncovers new targets for modification enzymes
Enzymes regulating genetic expression can be just as important as the genome itself, increasing evidence shows. The expanding field of epigenetics focuses on the multiple influences on DNA and surrounding molecules that determine whether genes are turned on or off during development and disease processes.
Scientists Clarify a Mechanism of Epigenetic Inheritance
Although letters representing the three billion pairs of molecules that form the "rungs" of the helical DNA "ladder" are routinely called the human "genetic code," the DNA they comprise transmits traits across generations in a variety of ways, not all of which depend on the sequence of letters in the code.
Computation to unravel how genes are regulated and shed light on how cells become different
A closer alliance between computational and experimental researchers is needed to make progress towards one of biology's most challenging goals, understanding how epigenetic marks contribute to regulation of gene expression.
USC researchers explore genetic causes for male infertility
Researchers at the University of Southern California (USC) suggest epigenetics, or the way DNA is processed and expressed, may be the underlying cause for male infertility. The study will be published in the Dec. 12 issue of Public Library of Science One.
Duke scientists map imprinted genes in human genome
Scientists at Duke University have created the first map of imprinted genes throughout the human genome, and they say a modern-day Rosetta stone - a form of artificial intelligence called machine learning - was the key to their success.
New molecules discovered that block cancer cells from modifying cell DNA
Researchers have discovered new small molecules that may prevent prostate cancer cells from turning off normal genes in a process that transforms normal cells into cancer cells.
Human embryonic stem cells remain embryonic because of epigenetic factors
A human embryonic stem cell is reined in - prevented from giving up its unique characteristics of self-renewal and pluripotency - by the presence of a protein modification that stifles any genes that would prematurely instruct the cell to develop into heart or other specialized tissue.
More Epigenetics News Articles
| © 2008 BrightSurf.com |