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Thursday, January 24, 2008

Our Dynamic Genome - Magnificent Software?

An article from October 2007 at Newsweek discusses the importance of a balance of microbes in our lives and their importance in our genetic make up and immune systems.

While this posting isn't about dogs, many of the basic ideas below do carry between species.


". . . What we need is more exposure to the good microbes, and the job of medicine in the years to come will be sorting out the good microbes from the bad."

"That's the goal of the Human Microbiome Project, a five-year multinational study that its advocates say could tell us almost as much about life as the recently completed work of sequencing the human genome. One puzzling result of the Human Genome Project was the paltry number of genes it found—about 20,000, which is only as many as it takes to make a fruit fly. Now some researchers think some of the "missing" genes may be found in the teeming populations of microbes we host." See more...
I'm not so sure we can really put all bugs into black and white categories, but the reality beyond doubt to me, is that we do need a balance of exposure to microbes. The whole idea probably doesn't seem all that alien to most, but germ exposure is probably far more important than most people think. Take a look some of Mike Johnson's musings on gut flora at Modern Dragons for another take on this perspective. I especially thought the bit about the fruit fly having another organism fused to its genome as particularly interesting examples of evolution. Fruit flies as natural genetically modified organisms? (having DNA of another species within) We know that cud chewing animals depend on the organisms in their gut which help them digest plant sources. Do they have bacterial genetic components that have become part of their genome? What about us? Our dogs? To what extent are we genetically modified in this way?

Another thing to look into regarding environmental influence on our genes is Comet Tail analysis, which gives some indication of how environment in the form of foods, drugs, pollution, and even FDA approved (Generally Recognized as Safe, GRAS) additives in our consumables affect the integrity of DNA in specific organs. Here's an example of comet tail analysis regarding the effect of phthalate on human sperm. How much of that sperm is still viable? I'm sure some of it may be damaged enough to die, but how much of it will bring new or damaging genetic information to a baby?

Pic at left from MSNBC article linked below - from Oct 2004 Nature.
I think that a lot of this is very important but the main thing to take away from all this is that our genes are not hard coded functional entities. They are dynamic and responsive to the environment. Why we don't have considerably more genes than a fruit fly probably has more to do with the complexities of the bulk of genetic exchange which occurs in our bodies through our lives, with our guts providing us with much of our immune function. Think of all the junk and medication that exert potential effect on DNA in our gut. They affect metabolism and make unknown changes to our normal flora. Speaking of normal flora, another favorite bookmark I often share is the fermentation page of Healing Crow which offers a lot of food for thought in the care of our normal flora and also discusses its importance.

Our genes seem to function in a manner similar to software in a computer. The ability of our genetic software to interpret internal and environmental data, to rebound from trauma and stress, and to find resources in order to generate pathways in order to survive, or simply to fail, are complicated and dynamic adaptations.

I'm baffled by this quote right at the end of this MSNBC article last year. Lander said he’s not concerned that the number of human genes has turned out to be so limited. “To the contrary, I think it’s great news,” he said, “because what it means is we already know a lot about most human genes.” I think I'll just chalk it up to an awkward closing to the article.

While we do have clear understanding of the exact number of chromosomes there are in different species, the actual numbers of different genes counted per species will continue to change. In part, due to refinement in how and which genes are counted, and how genes which are 'countable' are defined. (protein coding only? microRNA and apparently meaningless SNPs, etc - I think a lot of what has been called junk DNA may make some differences in disease resistance or survival as it relates to genetic diversity, but what do I know?) See Human Genome Project Information.

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Semavi Lady woofed at @ 1/24/2008 02:06:00 PM | Permanent link | (0) Comments

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