Many researchers have noticed that epigenetic memories tend to have a long life. They are often passed down for upto 14 generations or more.
While the encoded genetic information passed on via the germ cells from one person’s DNA to another is a solid fact of reality, there is the environment which needs to be brought into consideration as well.
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Environmentally, genetic changes can be made in the passing generations of individuals as well. In fact such changes can go on down the line for 14 generations in some animals which is very long time indeed.
Such was seen in a species of roundworm termed C. elegans nematodes. To see how the environment has an influence on genes, a group of scientists from EMBO in Spain did experiments on these particular worms.
These worms carried a transgene for a fluorescent protein. When this gene was activated, it made the worms glow under conditions of ultraviolet light. Then the researchers changed the temperature of the containers containing the worms.
At 20 degrees Celsius, these worms showed low activity of the transgene. They did not glow much. Then at 25 degrees Celsius, they lit up in a bright and shiny manner. Thus the fluorescence gene had been activated.
This phase of high temperature didn’t go on forever though. When they were moved back to cooler temperatures, it was supposed that their transgene activity would simmer down once again.
Yet no such thing happened. They continued to glow apace. This showed that they were having some memory of the erstwhile environment. This memory was then seen to get passed on to their offspring for seven generations which all continued to glow brightly.
None of these generations had experienced the high temperatures. The baby worms seemed to have inherited the environmental factor through both the eggs and the sperm of their respective maternal and paternal sides.
The team of researchers decided to investigate the matter further. Five generations of nematodes were kept at 25 degrees Celsius. Then their offspring were put under conditions of colder temperatures.
These worms continued to show higher transgenic activity down to 14 generations. This is a curious phenomenon. Normally, environmental changes last for just a few generations.
Scientists are saying that this may be a case of biology undergoing forward planning of some sort. Since worms do not live very long, they may be safeguarding their future generations from harm’s way by making them retain the epigenetic memory in their very cells.
This phenomenon has been seen not just in worms but also in rodents. The feature is difficult to measure in humans for obvious reasons.
Yet there remains a lot that is unknown and future research may prove that human beings too have strong epigenetic memories that get passed down the generations in a similar manner.
This research appear in the journal Science.