From Epigenetics: A Revolutionary Look at How Humans Work
It is something called the epigenome that keeps us from "having a long tail and a snout," said Randy Jirtle, an epigenetics research pioneer at Duke University in North Carolina.
Epigenome literally means "above the genome." It is a molecular marking system that controls gene expression without altering the DNA sequence. In a sense, the epigenome is the genome's boss.
In the initial weeks after an egg is fertilized — when its cells are rapidly multiplying and developing into something like a full-fledged body — the epigenome acts as an overbearing micro-manager. Each new cell has identical DNA, but the epigenome orders some cells to work as, say, skin cells and others to become neurons.
It was once thought this nitpicking backed off after birth, except for a brief resurgence around puberty. But recently scientists have realized the boss is always watching —taking stock of not only the genome but the world at large.
"The fascinating thing about it is that the epigenome is the mediator between the genes and the environment," said Liang Liu, a researcher at the University of Alabama at Birmingham
Food, pollution, toxic chemicals (such as those found in hard clear plastics), drugs, stress, even exercise and social interaction can all affect the epigenome and alter its attitude towards DNA, Liu said.
Sometimes, the epigenome responds to environmental cues by asking a gene, via a charged molecular messenger, either to start working or to work harder. For example, experiments by Michael Meaney and colleagues at McGill University have shown that when rat mothers are affectionate to their young, the baby's epigenome promotes a gene that helps the pup remain calm even in stressful situations. (Conversely, neglected rat pups grow up observably anxious.)
Other times, the epigenome demotes a gene. Many cancers, in fact, involve an irrational epigenetic firing of the gene that fights off tumors. The delivery of a molecular pink slip — often a methyl group — to the gene spurs a tight recoiling of the DNA spiral. The contraction makes it harder, or impossible, for transcription factors to interact with the gene — like stripping an employee of her Blackberry, computer and contact list.
The epigenome, however, is occasionally a wishy-washy supervisor. In some cases, epigenomic "decisions" can be reversed, Jirtle said.
Many medical treatments, Grayson said, such as those being developed for cancer and schizophrenia, try to coax the epigenome into changing its mind. Similarly, healthy nutrition and lifestyle choices can positively sway gene expression. "Food is truly medicine when you are talking about epigenetic changes," Jirtle said.
From New nucleotide could revolutionize epigenetics
The discovery of a new nucleotide in the mouse brain opens the door to a new domain of epigenetic DNA modification
Anyone who studied a little genetics in high school has heard of adenine, thymine, guanine and cytosine – the A,T,G and C that make up the DNA code. But those are not the whole story.
The rise of epigenetics in the past decade has drawn attention to a fifth nucleotide, 5-methylcytosine (5-mC), that sometimes replaces cytosine in the famous DNA double helix to regulate which genes are expressed. And now there's a sixth. In experiments to be published online Thursday by Science, researchers reveal an additional character in the mammalian DNA code, opening an entirely new front in epigenetic research.
The work, conducted in Nathaniel Heintz's Laboratory of Molecular Biology at The Rockefeller University, suggests that a new layer of complexity exists between our basic genetic blueprints and the creatures that grow out of them. "This is another mechanism for regulation of gene expression and nuclear structure that no one has had any insight into," says Heintz, who is also a Howard Hughes Medical Institute investigator. "The results are discrete and crystalline and clear; there is no uncertainty. I think this finding will electrify the field of epigenetics."
Genes alone cannot explain the vast differences in complexity among worms, mice, monkeys and humans, all of which have roughly the same amount of genetic material. Scientists have found that these differences arise in part from the dynamic regulation of gene expression rather than the genes themselves. Epigenetics, a relatively young and very hot field in biology, is the study of nongenetic factors that manage this regulation.
From Tough steak blamed on cows with human genes
Scientists will investigate ways to switch off a human gene that is thought to cause temperamental behaviour in both cows and humans in a new $1.35 million primary industries research project.
Primary Industries Minister Tim Mulherin, who announced the project ahead of the Australia's National Beef Expo 2009 in Rockhampton, says the new ground-breaking discovery could change the quality of beef.
"The genes thought to cause behavioural problems in humans are also found in cattle,'' Mr Mulherin said.
"We already know there is an association between the temperament of cattle and the tenderness of the meat, the more temperamental, the less tender.
"So if our scientists can learn how to switch off the gene that causes irritability in cattle then we can produce more tender meat which has a higher value to industry.''
Other factors to boost beef profits include annual calving and cows calving earlier in the season, which could lead to heavier offspring, he said.
Research leader, scientist Brian Burns, said the project focused on a new field of epigenetics, the study of modifications to genes other than changes in the DNA sequence itself.
From An intrusion of matriarchal consciousness
Right now a revolutionary paradigm shift is undergoing in the science of genetics. It is called epigenetics. The term "epigenetic" refers to heritable traits that do not involve changes to the DNA sequence. The DNA sequence is only part of the genome. The rest, which was earlier viewed as redundant rubbish, is now termed epigenome. Some epigenetic features are inherited from one generation to the next. Multigenerational epigenetics is today regarded as another aspect to evolution and adaptation. An example of this is the paramutation observed in maize. In humans, epigenetic changes have been observed to occur in response to environmental exposure, that is, a sort of Lamarckian inheritance (vid. Pembrey et al. 2006).
This is a most remarkable turnover in favour of depth-psychology,
The young science of epigenetics would be able to corroborate such notions. Not only climatological, epidemic, and nutritive experiences can be transferred to coming generations. Culture is the most fundamental force that has shaped man's life through the aeons. Its effect is, in all likelihood, established in the genome in a few generations.
|...The even greater surprise is the recent discovery that epigenetic signals from the environment can be passed on from one generation to the next, sometimes for several generations, without changing a single gene sequence. It's well established, of course, that environmental effects like radiation, which alter the genetic sequences in a sex cell's DNA, can leave a mark on subsequent generations. Likewise, it's known that the environment in a mother's womb can alter the development of a fetus. What's eye-opening is a growing body of evidence suggesting that the epigenetic changes wrought by one's diet, behavior, or surroundings can work their way into the germ line and echo far into the future. Put simply, and as bizarre as it may sound, what you eat or smoke today could affect the health and behavior of your great-grandchildren (Discover magazine, here).|
According to the above article in Discover magazine (here) "...the epigenome can change in response to the environment throughout an individual's lifetime." Hence, I propose that culture is very likely to play a role. The notion that factors of epigenetics could determine a person toward the animation of certain archetypes is consonant with this. I hypothesize that the individual could become more warlike in cultures which have historically been involved in conflict.
The article continues:
|...Remarkably, the mother's licking activity had the effect of removing dimmer switches on a gene that shapes stress receptors in the pup's growing brain. The well-licked rats had better-developed hippocampi and released less of the stress hormone cortisol, making them calmer when startled. In contrast, the neglected pups released much more cortisol, had less-developed hippocampi, and reacted nervously when startled or in new surroundings. Through a simple maternal behavior, these mother rats were literally shaping the brains of their offspring (ibid).|