February 19, 2004 (Ira Pilgrim)

Genetic Engineering in Nature

Now my own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose.

J. B. S. Haldane (1892-1964)

When I studied genetics at the University of California at Berkeley, it was the best that any university could offer in the subject. Now, in the world of molecular genetics, I find that I am a stranger in a strange land.

When genetic engineering started, I wrote the first act of a play about how, when the first atomic bomb was exploded, no one knew but that it might cause a chain reaction with the nitrogen in the atmosphere and destroy the earth. It was thought to be highly improbable, but no one knew for sure until that first explosion. We are still here, so the Earth wasn't destroyed. Now we know that all that nuclear explosions can do is kill large numbers of people and fill the Earth with radiation and radioactive elements. Despite this, life goes on. There is no question that it has caused an increase in human misery and that it will continue to do so.

What was known when I was a student was that specific genes were located at specific places on specific chromosomes. Genes could change by the process called mutation and mutations could be produced by ionizing radiation and some chemicals.

Now we know that genes can move from one place on a chromosome to another. This concept of "jumping genes" won Barbara McClintock the Nobel prize in 1983. Viruses were known to be made up of nucleic acids and a virus would take over the apparatus of a cell to duplicate itself. When the cell burst, virus particles were released to infect other cells. Biologists used this as a means of introducing genes into both plant and animal cells by making the genes part of a relatively harmless virus and infecting a plant or animal with it. Someone, long ago, once described viruses as "naked genes."

The bacterium that causes diphtheria is harmless. When it is infected by a specific bacterial virus (bacteriophage) and the viral genes become a part of the diphtheria bacillus, the bacterium produces a toxin that makes diphtheria a potentially fatal disease (Freeman,1951).

It is likely that every virus infection that I have ever had has introduced new genes into my body, Probably, those viruses are still there inside some of my cells. The virus that causes cold sores (Herpes simplex) resides in a the nerve ganglion and when my lip is exposed to the sun, the virus leaves the ganglion and I get a cold sore. If some of the many viruses that I have acquires infect the cells that give rise to sperm cells, some might have been passed on to my children. Scary!

Before the early 1900s all plant breeding was done by selection. The breeder would find a variety that was better in some ways such as the size of the fruit, growth patterns, size of the plant, flavor etc. and would propagate that variety. This went on for millennia. Mendel's work and that of his successors added precision to this process and specific genes for specific traits could be selected for. With the discovery that ionizing radiation could change (mutate) genes, the procedure changed and mutations could be deliberately produced rather than depending solely on chance. The germinal parts of the plant would be x-rayed and then the selection process for more desirable plants would begin. The genetic changes produced by the radiation were random mutations. Now, with genetic engineering, specific genes can be inserted into a plant or animal.

Now comes the hooker. Once a gene is inserted, the next step is to find out what the effect will be on the animal or plant. If the effect is what the breeder wants, the next step is to find out what the effect will be on everything else. Until this is done, no one knows whether the project has been a boon, a bust, or a big problem. That last step is where the big problems arise. A number of people have been credited with the statement "It's not what we don't know that gets us into trouble; it's what we know for sure that isn't so." What do we know about the ultimate effect of genetic engineering? Almost nothing! That brings us to the more general question of what do we do with every new invention or discovery which may have important consequences. Should it be tried or not? If it is tried, how can we make sure that undesirable effects are not perpetuated?

To the best of my knowledge, in all of history, not a single genetically modified animal or plant has supplanted the wild variety that it was produced from. Varieties of animals and plants from one part of the world have been introduced to other parts of the world and have replaced the indigenous varieties. Obvious examples have included the introduction of the dog and rabbit to Australia. In some cases, such as the rabbit, they have caused problems for people. In others, newly introduced species have replaced the indigenous animals and plants.

Varieties produced by people have never, to my knowledge, ever replaced a natural variety. If those beautiful tasty apples that we enjoy were no longer cultivated with loving care, they would disappear, to be replaced by tiny sour fruit. Nature is not interested in the size or flavor of a fruit, unless it enhances the perpetuation of the species.

I have written several essay on genetically modified food (www.mcn.org/c/irapilgrim/sci27.html and www.mcn.org/c/irapilgrim/sci35.html). In them, I discussed whether genetic engineering could be the boon to mankind that some people thought it might be, or a curse. You might want to read them.

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