If you find yourself battling a chronic disease, your DNA and environment may not be to blame as much as your ancestors' exposure to chemicals.
According to an article published in a magazine this month, environmental epigenetics, By a team from the University of Washington.
The researchers exposed three successive generations of rats each to a single toxic substance to mimic human exposure to chemicals at different times. The first generation was exposed to a fungicide called vinclozolin, an insecticide that kills various diseases on raspberries, lettuce, kiwi, grapes, and lawns. Vinclozolin, a known endocrine disruptor, can affect genital development and fertility, and may delay puberty.
A second generation of rats was exposed to a jet fuel hydrocarbon mixture. The third generation of pregnant females was then exposed to the insecticide dichlorodiphenyltrichloroethane, also known as DDT. In her 1962 book, marine biologist Rachel Carson famously warned of the dangers of pesticides, which were produced in large quantities during World War II. silent spring.
Three additional unexposed generations were bred before rats were tested. Researchers in Washington state looked for changes in the epigenome. The epigenome is made up of chemicals that modify the genome, much like computer software that tells it what to do, where to do it, and when to do it. The epigenome can be influenced, or “reprogrammed,” by environmental factors such as stress, diet, drugs, pollution, and toxic substances. The resulting changes are passed from cell to cell within individuals as cells divide, and from generation to generation within families.
The scientists observed that exposure to toxic substances “dramatically” altered the epigenetics of each generation, and that over time they observed “complex disease effects.” After the first toxic exposure, the incidence of obesity, kidney disease, and prostate disease increased with each successive generation. By the time the rats have bred to 3 unexposed rats, Over generations, the risk of developing such conditions increased by as much as 70%.
Michael Skinner, a WSU biology professor and corresponding author of the study, said previous studies have only looked at the effects of one generation of exposure to toxic substances. luck.
“We found that when multiple generations have different exposures, you end up with amplified or compounding effects on some diseases,” he says.
Obesity rates in the United States and Europe are both around 50%, three generations after the first exposure to DDT in the 1950s, he points out, and he points out that obesity rates in the United States and Europe are both around 50%, three generations after the first exposure to DDT in the 1950s. This suggests that the changes have created a population that is more obese and more susceptible to diseases such as obesity.
People who eat high-fat, high-sugar diets today are much more likely to become obese. But their ancestors, who weren't exposed to such toxic substances, might not have been like that, even if they had the same unhealthy diet, he argues.
“What this tells us is that the exposure of your grandparents will create a situation for you, your children, your grandchildren, and will continue into the next generation,” he added. “It doesn't mean you were directly exposed.”
Genome as a minor player
This intergenerational transmission of diseases is known as epigenetic intergenerational inheritance, which is “the only non-inherited form of inheritance that is currently recognized to exist,” Skinner said.
The effects of various environmental factors such as climate, nutrition, and toxic substances on the epigenome have been shown to span dozens of generations in Drosophila and hundreds of generations in plants.
“For mammals, we only live for 10 or 20 generations,” he says. “But we're also seeing transmission.”
Skinner says that while a person's DNA is an important factor in the development of disease, it is not as important as the epigenome.Case in point: the genetic mutations found in Angelina Jolie's BRCA1 gene and her BRCA2 gene, made famous by her 2013 movie new york times According to the editorial, it occurs in only 1% to 7% of breast cancer patients without a family history of breast cancer.
Professor Skinner says of these genetic errors, “There really isn't anything that regulates biology all that much.” Of the many DNA mutations each person carries, only 1% can cause disease.
“It's the changes in epigenetics that can cause disease.” [presentation] They become taller or shorter, obese or less obese,” he says.
Again a great example is breast cancer.
Breast cancer is not caused by a single gene, he says. “The BRAC2 gene was one of the first genes to be very well associated with breast cancer, but if you look at 100 people with breast cancer, only 1 out of 100 has a mutation in BRAC2. There is a possibility.”
“The idea that a single or small number of genes controls biology is not accurate,” he added. “Hundreds, if not thousands, of genes are required” to cause any disease state, and all contributing genes must be “turned on” by the epigenome.
The study is a wake-up call about how environmental exposures can affect health, Skinner said. Even if it does not affect the health of our generation, it will definitely affect the health of the next generation, and perhaps forever.
“We now realize that what we're doing to ourselves in terms of exposure, while it can have an impact, doesn't have that much of an impact,” he added. “But it is having a dramatic impact on subsequent generations.”
