STUDIES IN EPIGENETICS

Experimental subjects found to have inherited environmental or traumatic genetic markers include rats, worms and humans.

Labs that insert “transgenes” into an animal for research can add genes that create a fluorescent protein. It’s a useful tool in tracking which animals inherit which gene. They glow. A Spanish group found that a worm with this transgene glows a little bit when it is kept cool, but glows more if it lives for a while in warmer conditions. Here’s the epigenetic part: Once it warms up, it keeps glowing brightly after it is moved back to cool conditions. As well, its offspring will glow brightly at cool temperatures for the next seven generations, even if they themselves have never been warmed up. The work comes from the Josep Carreras Leukaemia Research Institute in Spain. The same worm species, called C. elegans, shows up in a Duke University study last October. If the mother worms are underfed, their offspring will grow more slowly than normal worms, but they are better able to cope with famine conditions. The effect lasts a lifetime. “They have a memory of famine,” writes Duke biologist Ryan Baugh. Famine figures prominently in human epigenetics studies, beginning with a region in northern Sweden called Överkalix, where there was a pattern of intermittent crop failures so that people swung between feast and famine. Scientists started studying records of the groups of people of Överkalix born in 1890, 1905 and 1920, and their children and grandchildren — and found all kinds of effects on grandchildren associated with what people had eaten two generations earlier. Among the results: Women had a doubled risk of cardiovascular disease if their paternal grandmother had a year of good food supply following famine years in the time shortly before puberty, defined as ages eight to 10. The food supply of the three other grandparents wasn’t significant. It wasn’t the goodness of the food that did the damage, the authors wrote, but rather the change: “The shock of change in food availability seems to give specific transgenerational responses.” Going from a very good year to a bad year also affected the lifespan of descendants, but the pattern was different. Another: Grandsons of Överkalix boys who had plenty of food immediately before puberty — when sperm cells are maturing — died six years earlier than men whose grandfathers experienced famine at that time of life. Often the cause of death in the higherrisk group was diabetes. A study at Uppsala University in Sweden links tea to epigenetic effects in women. But “links” is a vague word in science, often meaning that there appears to be some connection but no one has pinned it down. In this case, the Swedes can see changes happening in genes that are related to estrogen and to cancer. But are they good or bad changes? No one can tell. A side note: Men show no such changes. And coffee has no effect. Finally, there’s a whole raft of studies about the mothering techniques of rats. A common point is this: attentive rat mothers have offspring that are less stressed than those that show less interest in their young, and there is a difference in epigenetic marks between the two groups.