Parental stress passed on to children28th June 2011
Stress caused by extreme circumstances like starvation could potentially be passed on to the children or even grandchildren of the person who suffers it.
Scientists studied mutant fruit flies to help find out how ill effects suffered by one generation can be passed on to descendants.
The process is known as epigenetic change, which means that while the basic genetic structure is unchanged, chemical footprints affect certain genes, muting or cancelling out their effect.
Mice that have been subjected to stress for two weeks after birth will have offspring that show signs of depression and anxiety, even if maternal care is plentiful, previous studies have shown.
Researchers now think that stress endured by parents and grandparents could account for susceptibility to a string of common health problems, including obesity, mental illness, diabetes as well as anxiety levels.
A team led by Shunsuke Ishii at Japan's Riken Tsukuba Institute, Ibaraki, have managed to identify the molecular mechanism through which stress is inherited.
Ishii said they were confident that they could now explain exactly how the effects of stress can be handed down without altering genes or DNA.
Chemical or environmental stress detaches a protein from chromatin, the densely packed DNA that chromosomes are made from.
The protein, known as activating transcription factor 2 (ATF-2), usually "zips up" genes, binding the chromatin tightly.
But once it is detached, previously hidden genes can become active.
If the cell that was originally stressed is an egg or a sperm, then the unzipping factor will be carried into all the cells of any offspring, affecting the expression of their genetic make-up.
The researchers used fruit flies that had been given red eyes through genetic mutation, but via a normally dormant gene. Only flies with "unzipped" chromatin would actually express this gene.
They then subjected a group of the mutated fruit flies to stress by exposing their eggs to heat or saline solution.
When the group mated with healthy fruit flies, the red-eye mutation was expressed in the first two generations of offspring, but not the third.
But if the red-eyed flies were subjected to further stress, the effects of the "unzipping" lasted for three generations.
The team concluded that sustained stress over multiple generations resulted in the altered chromatin state being inherited by subsequent generations.
The mammalian counterpart to ATF-2 is ATF-7. While psychological stress in mice had been shown to trigger chromatin changes, no-one had yet studied the effects of stress on mammalian offspring.
Experts hailed the research as a ground-breaking insight into the molecular workings of stress at a genetic level.
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Title: Parental stress passed on to children
Author: Luisetta Mudie
Article Id: 18935
Date Added: 28th Jun 2011