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Genes, DNA, diet, heredity, and disease.

New findings about genetics, diet, and disease are both startling and encouraging. Thus in Matt Ridley's Nature via Nurture: Genes, Experiences, and What Makes Us Human (2003), experiments are reported which show that a mouse's brain cells are affected by external stimuli. In a way, this opens the door to Lamarckism, the transmission and inheritance of environmentally caused characteristics--heretofore discounted in evolutionary biology. (Albeit mutations are produced by zapping with radiation and the use of bioactive chemicals such as colchicine. However, if say one's arm or leg is amputated, this evidently is never passed along.) An update by Emma Young is titled "Strange Inheritance: It's not just your parents' genes but also their experiences that determine your genetic make-up," published in New Scientist, July 12, 2008.

In the Science Times section of the New York Times, November 11, 2008, concerns are expressed about genes, titled "Beyond the Genes." The highlighted leadoff statements are as follows: "Only 1.2 percent of the genome is made up of classic genes. Scientists are exploring the other 99 percent, in the process uncovering new secrets and facing new questions." The text includes articles by several authorities, abstracted as follows.

In "The Promise and Power of RNA," Andrew Pollack first mentions that some persons have a highly active form of a certain protein resulting in high levels of cholesterol, while those with an inactive form have low cholesterol--and a low risk of heart attacks. Instead of treatment after the fact, it has been found that a new approach, called RNA interference, halts production of the protein by silencing the gene that contains its recipe.

In "Now: The Rest of the Genome," Carl Zimmer describes the work of bioinformatician Dr. Sonja Prohaska at the University of Leipzig. Dr. Prohaska and her colleagues no longer perceive a typical gene as a single chunk of DNA encoding a single protein, for several different proteins may be formed from a single stretch of DNA. In fact, most of the molecules produced may not even be proteins, but another chemical, this being RNA. Thus the familiar DNA helix no longer has a monopoly on heredity, whereby other molecules clinging to DNA can cause striking differences between two organisms having the same genes. And these extraneous molecules can be inherited along with DNA. "The gene, in other words, is in an identity crisis."

In "Scientists and Philosophers Find That 'Gene' Has a Multitude of Meanings," Natalie Angier reviews the basics. She notes that the latest word is that genes, per se, are simply too feeble to account for much of anything. Traditionally, genes are the lineup of DNA letters serving as instructions for forming the body's proteins. But upon closer examination, it turns out the less instructive they seem, and which are no longer a "blueprint for life." Not only is DNA discounted, but its chemical cousin RNA is found to be increasingly involved. Whereas the conventional wisdom has been that, "DNA makes RNA makes protein," it is found that RNA can itself transmit genetic secrets directly to the next generation (and, it may be mentioned, can instruct DNA). It can also act like a protein, and can catalyze chemical reactions (that is, act like an enzyme). The findings replace simplicity with complexity, as indicated by R. Beckwith of Harvard Medical School and Eric S. Lander of the Broad Institute. A consensus reached by other researchers is that the parlance of molecular biology needs an overhaul. In fact, Evelyn Fox Keller--a science historian and professor emeritus at MIT--in speaking of genes, remarks: "The language is historical baggage." In assessing the role of genes, Dr. Keller further states: "But the notion of the gene as the atom of biology is very mistaken. DNA does not come equipped with genes comes with sequences that are acted on in certain ways by cells. Before you have cells you don't have genes." As to DNA, it doesn't do anything by itself, and has meaning only in the context of the cell. Cells are the key, but the situation is "irreducibly complex," and not fully accessible to rational analysis. And if genes cannot explain yourself, Angier says that you can always "blame it all on your mother."

As reported by Laurie Garrett in The Coming Plague (1994), a complicating factor is that genes can move about, or jump about--even share with other organisms (e.g., microbes), or hide- a process called transpositioning, with the mobile genes referred to as transposons, and as distinguished from the more stable forms called plasmids (Garrett, The Coming Plague, p. 225). The result can be radical changes in the organism. It is as if a game of Scrabble occurs.

The subject was also explored in the November 2006 issue of Discover in an article by Ethan Watters titled "DNA Is Not Destiny: The new science of epigenetics rewrites the rules of disease, heredity, and identity." The word epigenetics pertains to effects from gene activity during gene differentiation and development. In this instance, there are studies on agouti mice that have a particular gene (the agouti gene), which makes the rodents ravenous and yellow--and also prone to cancer and diabetes. Ordinarily the offspring mimic their parents, but could be altered to a brown color along with being cancer and diabetes free by a change in the mom's diet. The diet was rich in methyl donors, as found in the environment and in such foods as onions, garlic, beets, and supplements. "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." Moreover, the researchers found that " ... common signaling pathways known to lead to cancerous tumors also activate the DNA-methylation machinery; knocking out one of the enzymes in that pathway prevents the tumors from developing." On the other hand, when genes that ordinarily suppress tumors are methylated, the tumors will metastasize. (Here "metastasize" evidently signifies a change in state, condition, or size, rather than a migration from one part of the body to another.) However, when genes that ordinarily prevent tumor growth are demethylated, the genes then cause tumors to grow.

The above seems to be a mixed bag, but researchers are focusing on "methylation diets" as a means of staying healthy. Green tea is apparently one such agent.

The notation is made that more than DNA is inherited, for chromosomes are what are inherited and which are only 50% DNA; the rest is composed of protein molecules that carry the epigenetic marks and information.

Furthermore, the mother's very behavior can cause epigenetic change in the offspring. Enter nurturing and brain development.

A further consequence is that personality traits may be affected by the epigenetic changes. Thus, quoting a psychologist, "If you had a generation of poor people who suffer from bad nutrition, it may take two or three generations for that population to recover from that hardship and reach its full potential." There is an impact of poverty, war, and the dislocation of a population

In the August 2006 issue of Discover, a short article by Jessica Ruvinsky describes experiments on mice with a cancer cell strain producing a 100% death rate. One mouse, however was totally resistant, as were some 40% of the offspring. Somehow, a genetic tweak was able to unleash a barrage of white blood cells that killed the tumor. Not only this, but blood cells from these anticancer mice were injected into other mice, they in turn became cancer resistant. There is thus the possibility that injecting people with cancer-fighting blood cells could transfer immunity--albeit others warn that the donated cells could instead attack the host.

(A reminder is of the work described in Stephen S. Hall's A Commotion in the Blood [1997], in which a certain Frau H. proved immune to cancer. This sort of immunity could also act as the defense against a new concern, about contagious cancer in humans. Not to mention that a proliferation of white blood cells as in leukemia might have an anticancer effect on other forms of cancer. More broadly speaking, the subject is biochemical individuality.)

Another complication is that "cancerous stem cells" are found to exist, and which are resistant to known treatments as described in my book Cancer and the Search for Selective Biochemical Inhibitors (2007). However, research for inhibitors or blockers is proceeding, some from plant sources, in line with the above-cited article by Ethan Watters, about epigenetics and diet.

E. J. Hoffman

P.O. Box 1352

Laramie Wyoming 82073

307-742-3458

References

Garrett L The Coming Plague: Newly Emerging Diseases in a World Out of Balance. New York: Penguin Books; 1994.

Hall SS. A Commotion in the Blood; Life, Death, and the Immune System. New York: Holt; 1997.

Hoffman EJ. Cancer and the Search for Selective Biochemical Inhibitors. 2nd ed. Boca Raton FL: CRC Press, Taylor & Francis; 2007: 403-416.

Ridley M, Nature via Nurture: Genes, Experiences, and What Makes Us Human. New York: HarperCollins; 2003.

Watters E. DNA is not destiny: the new science of epigenetics rewrites the rules of disease, heredity, and identity. Discover. Nov 2006:32-37,75.

Young E. Strange inheritance: it's not just your parents' genes but also their experiences that determine your genetic make-up. New Scientist. 12 July 2008:28-33.
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Title Annotation:Letters to the Editor
Publication:Townsend Letter
Article Type:Report
Geographic Code:1USA
Date:May 1, 2009
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