Epigenetics

[eeeefarm]

Rather than continuing to drag the other thread way off topic, I am starting a new thread here.

@DebraDownSouth:

Yes but that is much like, lets say, diabetes. Identical twins… one eats right, the other eats horrible-- identical but one develops diabetes.

On the twins, btw, I recently read that they actually are NOT identical, that on closer examination there are in fact some differences and I think (have some projects so can't research at the moment and I forget) the issue was the division of the cells not so perfectly even as previously thought depending on when they split.

On polygenetic traits, yep, remember that from genetics classes long ago.

However, even in the womb, placenta placement can change nutrition and development–so maybe that is also enough to effect some phenotype expression changes. I have known quite a few identical twins– maybe 10 sets. And while I could tell them apart, a lot was styles, weight and behaviors which most certainly have to do with other things, not really phenotype expression.

Yes, I think this can definitely be the case…..but there is so much more that has been discovered. Consider this:

_Back in 2000, Randy Jirtle, a professor of radiation oncology at Duke University, and his postdoctoral student Robert Waterland designed a groundbreaking genetic experiment that was simplicity itself. They started with pairs of fat yellow mice known to scientists as agouti mice, so called because they carry a particular gene?the agouti gene?that in addition to making the rodents ravenous and yellow renders them prone to cancer and diabetes. Jirtle and Waterland set about to see if they could change the unfortunate genetic legacy of these little creatures.

Typically, when agouti mice breed, most of the offspring are identical to the parents: just as yellow, fat as pincushions, and susceptible to life-shortening disease. The parent mice in Jirtle and Waterland's experiment, however, produced a majority of offspring that looked altogether different. These young mice were slender and mousy brown. Moreover, they did not display their parents' susceptibility to cancer and diabetes and lived to a spry old age. The effects of the agouti gene had been virtually erased.

Remarkably, the researchers effected this transformation without altering a single letter of the mouse's DNA. Their approach instead was radically straightforward?they changed the moms' diet. Starting just before conception, Jirtle and Waterland fed a test group of mother mice a diet rich in methyl donors, small chemical clusters that can attach to a gene and turn it off. These molecules are common in the environment and are found in many foods, including onions, garlic, beets, and in the food supplements often given to pregnant women. After being consumed by the mothers, the methyl donors worked their way into the developing embryos' chromosomes and onto the critical agouti gene. The mothers passed along the agouti gene to their children intact, but thanks to their methyl-rich pregnancy diet, they had added to the gene a chemical switch that dimmed the gene's deleterious effects._

http://discovermagazine.com/2006/nov/cover

I think the implications are enormous. If the diet of the dam can have such a dramatic effect for the better, can it not also have a huge impact for the worse? I think this research is unveiling a lot of possibilities that may be relevant to the health effects of our lifestyle on our dogs. Consider that many of the current health problems in dogs were unknown back when the family dog ate whatever scraps he was offered. Dogs evolved as scavengers. Perhaps we do them no favours by providing a diet that may be too rich for their needs. I have seen a similar trend in horses. Starting in the '70's, if memory serves, suddenly we began seeing all these legs problems in foals. Contracted tendons, club feet. Even the vets were mystified at first. Much of the problem seems to have been a disruption of the calcium/phosphorus balance, and in my opinion it wasn't about the ratio being fed but about too much protein affecting absorption. That's a simplistic explanation and the issue is more complicated, but even in humans, consuming a diet high in protein can put you in a negative calcium balance.

But I digress. Suffice it to say that epigenetics may hold some interesting revelations for us down the road.

On another note, I see there is a thread on this forum relating to the Russian Fox Study.

http://www.basenjiforums.com/showthread.php?t=8390&highlight=Russian+study

I was going to mention it as being one of the more interesting examples of how selecting for one trait can affect others so dramatically. And I wonder again whether selective breeding since Basenjis left Africa could have resulted in some unexpected health issues, among other things….

[Andrew]

I don't get on here often, so I just saw this. What a fascinating topic!!! Thank you for sharing.