| Muck and Mystery Loitering With Intent |
blog - at - crumbtrail.org |
The research indicates that children conceived during the Dutch Hunger Winter in 1944-45, caused by a food embargo on the Netherlands in World War II, experienced persistent detrimental health effects six decades later. The authors found that the children exposed to the famine during the first 10 weeks after conception had less DNA methylation of the imprinted IGF2 gene than their unexposed same-sex siblings. By contrast, children exposed to the famine at the end of pregnancy showed no difference in methylation compared to their unexposed siblings. These findings support the conclusion that very early development is a crucial period in establishing and maintaining epigenetic marks. Epigenetic changes, while not altering the DNA sequence, can alter which genes are expressed. Genes that might otherwise be activated could be silenced by epigenetic changes or vice versa, and this could impact an individual's risk for adverse health outcomes later in life.This may be the first human evidence, but it has long been known for plants and other animals, and there was no good reason to suspect that things were different for humans."We believe that our study provides the first evidence that certain environmental conditions early in human development can result in persistent changes in epigenetic information,"
Those of us who work in ag live with this reality. If you are the sort of jerk who doesn't care for his gestating animals then the chances are that you will pull the herd down. Similarly, if you wish to buy stock it is worth considering how they were raised for several generations. They may have genetic potentials not reflected in the current herd - which you can exploit over time - and they may not achieve to their potential in the current or subsequent generation.
There are issues with crop plants too. One of the benefits of local adaptation is that plants have a chance to express epigenetic changes that make them better suited to agronomic conditions. If drought is a regular occurrence, for example, the daughters of new varieties may have epigenetic changes that allow them to better cope. The DNA is the same, but its expression is altered.
It would be good if there were more studies on this subject and the findings were widely communicated. I'm not sure how much of what I think I know is solid, or what factors matter most. For instance, the idea that it is the first trimester of gestation that really matters is an important distinction. And are there specific nutrients that matter more than others?
This may be the first evidence of epigenetic changes to the DNA, but there has been evidence that, for example, underweight babies have underweight babies themselves when they grow up, and that this effect may go forward to a third generation. Methylation may be an underlying mechanism.
I hope people don't mistake epigenetic change of the sort you describe for possible adaptation to drought are Lamarckian.
It's a fuzzy area somewhere between the poles of that old conflict. That debate did happen about some of the plant adaptation discoveries. It's complicated.
Posted by: back40 at October 31, 2008 05:18 AMI seem to recall an analysis of Galapagos finches along the same lines. Thick beaks and thin beaks are expressed generation to generation depending on the food supply, which is quite volatile; turns out that there's a specific protein involved in toggling gene expression, if I remember correctly.
Posted by: Carl at October 31, 2008 04:19 PM