Man-made life

For as long as I remember, there have been jokes and pop-culture references to scientists creating life in a test tube–usually with the understanding that such a thing was an impossibility outside of horror movies.

But last week scientists in the U.S. announced their intention to create the first completely artificial form of life, a man-made microbe that has never existed in nature in any form.

The scientists behind the project are Dr. Craig Venter, already famous for heading up the privately-funded effort to discover the complete human genome, and Dr. Hamilton Smith, a Nobel Prize-winning geneticist.

Dr. Venter first proposed creating an artificial life form in 1999, after a team from the Institute for Genomic Research in Maryland (which Dr. Venter founded) reported that they had discovered what appeared to be the minimum number of genes necessary for life.

Genes are the instructions coded in DNA that tell cells what proteins to manufacture in order to grow, reproduce and otherwise function.

The scientists worked with a bacterium called Mycoplasma genitalium, a harmless microbe that normally lives in the human genital tract and lungs. It has the fewest number of genes of any known organism–517 compared to between 80,000 and 140,000 for humans. The scientists disrupted its genes one by one to see which ones it had to have in order to keep working. Their research suggested that 265 to 350 of the genes in the bacterium were essential, with the exact number depending on the environment (some genes were only necessary when certain nutrients were present, for example).

Knowing which genes were essential immediately raised the possibility in Dr. Venter’s mind that scientists could create an artificial microbe, because we already have the capability of synthesizing DNA to order.

But that possibility raised ethical questions, and so Dr. Venter formed a panel of ethicists and religious leaders to discuss the implications of artificial life. The panel concluded that the project would be ethical if the ultimate goal was to benefit mankind and if all appropriate safeguards were followed.

One safeguard is the organism chosen as the template for the new bacteria. Not only is Mycoplasma genitalium harmless to begin with, the manufactured version will not contain the gene that allows it to adhere to human cells.

In addition, the manufactured bacterium will not contain the genes that would allow it to survive hostile environments. The new life form will only be able to live in the lab, where the narrow environmental conditions it needs are maintained.

Finally, it’s likely that only limited details of the work will be widely published, to prevent bioterrorists from using the technology to develop more deadly microbes.

Although this initial experiment is pure research, the ultimate goal is to create bacteria to order to perform useful functions. One specific goal Dr. Venter has mentioned is the creation of bacteria that can produce large quantities of hydrogen, providing a cheap source of a fuel that, widely used, would reduce our dependence on fossil fuels and thus help prevent catastrophic global warming. That long-term possibility is one reason the research is being funded to the tune of $3 million by the U.S. Department of Energy’s Office of Science.

We might also be able to some day create artificial bacteria that could actually remove excess carbon dioxide from the atmosphere, or clean up toxic spills.

The first step of the project will be to create an artificial chromosome (the structure that holds genes in place in the nucleus of a cell) packed with about 300 manufactured genes, based on the essential genes discovered in 1999. The scientists will then place the artificial chromosome in the nucleus of an M. genitalium bacterium whose own genetic material has been removed. If the experiment works, the new cell will be able to divide and produce a new generation of cells, all of which will contain the new man-made genetic instructions.

Don’t look for results right away; the project has funding for three years and may take longer. But if it works, then the dream of “test-tube life” will have become a reality–and man-made microbes may soon be working for us in ways that today we can barely imagine.

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