Sunday, July 15, 2007

On life

I'm not a biologist, far from it. But I have an open mind and am interested in reading up on subjects about which I know little. For Christmas 1991, Derek (who has a degree in marine biology) gave me a softcover book whose title is simply "Microcosmos". I suppose Derek's intent was meant as a juxtaposition to my interests in the "macrocosm" which is a subject of study in astronomy (a hobby of mine). This book was written by Dr. Lynn Margulis and Dorion Sagan. Its subject is the evolution of life from the beginning (four billion years ago) to now.

After many partially successful starts, so they write, the most basic form of life was found in the form of single cells without nucleus (prokaryotic cells). Other cell forms evolved which preyed on these prokaryotic cells and invaded them. Most of the prokaryotes died as a result. Since killing the host takes the invader with it, this is a self-defeating process. There were some prokaryotes, however, which got "sick" but did not die, even though they now contained the foreign invaders. Over time, the invaders, whose task it was to subvert the cell machinery to their own purposes (any virus does the same thing today), gave up some of their own functions (those that duplicated the identical function in their hosts), and the hosts acquired some beneficial functionalities from their invaders which they had not had before. This result then made host and invader dependent on each other - we call this process a symbiosis. Eventually, our current cell system evolved in such a way that these formerly foreign invaders are a necessity for a viable cell. Cells that contain this symbiotic arrangement are called eukaryotic cells. The inclusions are seen easily under a microscope - we call them mitochondria and nuclei. Most life forms, especially we humans, are made up of eukaryotic cells whose individual function depends critically on this symbiotic relationship.

Why am I mentioning all that? As may you know from my previous posts and Derek's own blog (http://www.penmachine.com/), Derek developed colon cancer within the last year. The aforementioned book states on page 148 of the softcover edition (Simon and Schuster Touchstone, publisher): .... "The body is totalitarian in its regulation of genes. Once a cell becomes a muscle cell, for example, it is so forever. The only exception to this rule of permanent roles within the body is during cancer, when cells seem to revert back to the more promordial condition of reproducing continuously, without regard to their place or function in the body. During cancer, chromosomes break apart and mitochondria reproduce even more rapidly then the cells of which they are a part..... ..... It is as if the uneasy alliances of the symbiotic partnerships that maintain the cells disintegrate. The symbionts fall out of line, once again asserting their independent tendencies, reliving their ancient past. The reasons, of course, are not all that clear, but cancer seems more an untimely regression than a disease. Genes are regulated and cells differentiated in the body by a complex interaction of biochemicals within the body. When these biochemicals are diluted by the introduction of cigarette smoke, sodium nitrate, and other carcinogens, they cannot perform their task. Consequently cells tend to behave like children in a class room whose teacher has left: they go wild, they get out of their cellular 'seats', they play and reproduce in an unregulated, wanton fashion."

Who knows what kicked off this serious turn of events in Derek's colon? It is easy to describe this condition in physical terms, but the emotional component for those who are afflicted, and their family and friends cannot be so easily understood. Derek never smoked, but what about the preservatives in our foods (among which are nitrates), second-hand cigarette smoke, pesticides used in agriculture, cosmic rays? We'll likely never know.

The irony of Derek giving me a book years ago, some of whose content describes a situation of which he is now a victim, is not lost on me.

For those of you who are interested in the book, it is still available here:

http://www.amazon.com/Microcosmos-Billion-Years-Microbial-Evolution/dp/0520210646

2 comments:

Christa Giles said...

Verrry interesting! When I saw the title of the book, I was expecting something like the movie of the same (or at least similar) name, that features teeny tiny cameras attached to bugs n such so we can see what they do in a day.

Similar enough, I guess, but different.. I'll add it to my reading list!

Shane Hendricks said...

Hi,

Well, my day gig is in the molecular diagnostics realm. I just did complete my MS in molecular a few months ago.

Part of my studies included an oncology course, and we basically read journal articles back to the beginnings of cancer research up through to the present day. The biochemical causes of cancer are multifaceted and complex; mutagens aren't solely responsible for cancer, just as genetic predispositions aren't. All of our cells have a background mutation rate, so we can spontaneously get cancer when our DNA repair mechanisms--a normal part of everyday life--fail or go out of whack.

I guess what I'm trying to say is that--try what one may--there's no way to completely eliminate the risk of cancer, even if one eats nothing but the healthiest of food, avoids sunlight, drinks the cleanest water, doesn't smoke, doesn't drink, etc. If food preservatives were a strong carcinogen then I'd expect to see a lot more of us with cancer, epidemiologically speaking; maybe preservatives work in concert with other mutagens, or maybe not. Obviously, there are associations and increased risk with certain behaviors and exposures, but it's hard to pin down a sole cause in all cases.

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