Mouse Dietary Epigenetics

Last week I discussed epigenetics inheritance of traits through mechanisms other than differences in DNA sequences); this week we look at a study showing that the diet of male mice before mating can affect the physiology of their offspring - through an epiegenetic type mechanism that involves tRNAs instead of modification of DNA.
 

Two teams of researchers conducting independent experiments have found evidence that indicates that what a male mouse eats prior to mating with a female mouse can have an impact on the offspring that result. The first group, from several institutions in China, ran experiments testing the impact of male mice eating a high fat diet, on offspring, while the second team, with members from the U.S. and Canada, tested the impact of a low-protein diet by male mice prior to siring offspring. Both teams describe their experiments and results in papers published in the journal Science. For many years it has been assumed that the only impact male mammals can have on their offspring, due purely to mating, is from the DNA they carry in their sperm. In recent years, however, some study results have suggested that they can have another impact due to what are known as transfer RNAs (tRNAs). These two new studies add more evidence, suggesting that tRNA fragments can carry information that adversely impacts offspring. In the first study, the team fed one group of mice a high fat diet, while another group was fed a normal diet. Sperm was harvested from both groups and used to impregnate female mice. Offspring had their weight monitored along with their level of glucose intolerance and insulin resistance. The team reports that the offspring of the males fed the high fat diets did not gain more weight than those from the control group, but they did develop an impaired resistance to insulin and glucose intolerance—precursors to diabetes. To ensure that the change was due to tRNA fragments, the team ran the same experiment again, but the second time around they purified the RNA before injection into the eggs. The resulting offspring developed intolerance to glucose but did not develop insulin resistance. In the second study, the researchers conducted the same type of experiment but had the male study group eat a low-protein diet. The team reports they found no differences between the offspring except for changes to a group of genes that are responsible for the development of stem cells. Though not studied yet, it appears likely that the same results would occur with humans, which suggests that couples looking to have children ought to be aware of or modify the diets of both potential parents.

So, it is not only true that "you are what you eat" - it is also true that your children are what you eat. Be advised and choose carefully.