Monday, October 06, 2003

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The New York Times A Pregnant Mother's Diet May Turn the Genes Around
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"With the help of some fat yellow mice, scientists have discovered exactly how a mother's diet can permanently alter the functioning of genes in her offspring without changing the genes themselves."

"The research is a milestone in the relatively new science of epigenetics, the study of how environmental factors like diet, stress and maternal nutrition can change gene function without altering the DNA sequence in any way."

redux [09.13.01]
The Scientist The Meaning of Epigenetics
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"The term was introduced by Conrad H. Waddington in 1942.1 To paraphrase an erudite epistolary exchange in Science, he is said to contrast genetics with epigenetics , the study of the processes by which genotype gives rise to phenotype. In 1942 we had barely any clue as to what those processes are, so "epigenetic" had no connotation of the underlying chemical mechanism, whatever it was that modulated cell differentiation.

In 1994, as cited in the same issue of Science, Robin Holliday voiced a commonly apprehended drift in meaning, and redefined epigenetic as "Nuclear inheritance which is not based on differences in DNA sequence." These two memes are freely circulating and can cause muddle or mischief mainly when they recombine, namely when epigenetic-H is automatically applied to epigenetic-W."

"This neology of nucleic, epinucleic, extranucleic, has attracted few followers, I think largely because so few people had really thought through the distinctions. There is much merit in Ben Johnson's caution about unbridled proliferation of terms: "A man coins not a new word without some peril, and less fruit; for if it happen to be received, the praise is but moderate; if refus'd, the scorn is assur'd." But is a polysemy to be preferred, with thought-muddling as a further peril?"

redux [08.16.01]
Science Behind the Scenes of Gene Expression
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"Some of the weirdest genetic phenomena have very little to do with the genes themselves. True, as the units of DNA that define the proteins needed for life, genes have played biology's center stage for decades. But whereas the genes always seem to get star billing, work over the past few years suggests that they are little more than puppets. An assortment of proteins and, sometimes, RNAs, pull the strings, telling the genes when and where to turn on or off."

""The unit of inheritance, i.e., a gene, [now] extends beyond the sequence to epigenetic modifications of that sequence," explains Emma Whitelaw, a biochemist at the University of Sydney, Australia."

""[Epigenetic effects] give you a mechanism by which the environment can very stably change things," says Rudolph Jaenisch, a developmental biologist at the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts. Researchers are hoping to harness these effects to design drugs that correct cancer and other diseases brought on by gene misregulation."

redux [07.11.00]
Wired News Following Cancer's Red Flags

"Genes are tricksters. They can be turned on or off -- and whether they're on or off decides whether the gene-owner will develop disease.

Gene researchers have embarked on a new field of research, called epigenomics, to determine whether genes are in the on or off position. This type of marker could prove an important diagnostic or therapeutic tool for all types of cancer.

"At Johns Hopkins, researchers are performing clinical trials on about 15 patients with leukemia and other cancers to find out if epigenomics might give pharmaceutical companies a lead for developing cancer drugs.

The research, like all epigenomics research, is studying a chemical found in everyone's DNA called cytosine. Cytosine is the only chemical of the four that make up human DNA (the others are adenine, thymine, and guanine) that is prone to a phenomenon called methylation. When cytosine is methylated, it tuns off its gene."