Biologists are taking several steps closer to building cells from basic raw materials. For the meaning, creating artificial life in the laboratory, many ethical and moral consequences
Michael Speer, Scientific American
If you think of the biological cell as a device that can be programmed and that also happens to be alive, you will begin to understand the idea on which the developing field called synthetic biology is founded. Instead of trying to uncover the intricacies of natural biological systems, the "synthetic biologists" aim to build simple living cells from basic and readily available raw materials. No one has done it yet, but more and more scientists and engineers are taking the first steps toward making life forms to order.
High on their priority list is the task of programming an artificial cell. The functions of the living cell are controlled by complex networks, or circuits of genes that maintain mutual relationships between them. Just as engineers assemble electronic circuits with switches and oscillators, so the new breed of biologists hope to build modular genetic circuits that can be "connected and activated" at will.
Such a modular circuit was described on June 1, 2004 in the Proceedings of the National Academy of Sciences. James J. Collins and his team at Boston University designed genetic on-off switches to control natural networks, such as those that control protein production, inside a bacterial cell. The research not only demonstrates that it is possible to program cells by using modular design strategies, but it also serves as a model for a new category of drugs that could modulate the activity of the networks. Collins is currently busy trying to reverse-engineer how some genetic networks work - a technique that may, in time, help scientists determine the molecular targets of new drugs.
Collins' modular genetic circuits were built using standard cloning techniques, simply by cutting and pasting natural DNA. At the end of 2004, another group of scientists, led by George M. Church of Harvard Medical School, described a new method for making synthetic DNA. For many years they know how to build DNA in the laboratory - the programming code of life. But Church and his colleagues created with the new method all 21 genes necessary for the production of a subunit of a ribosome, otherwise known as the intracellular machine for building proteins. The ability to build long sequences of synthetic DNA allows scientists to create new genes that did not exist before.
Recently, Church announced a new technology for determining DNA sequences, which should be about nine times faster and cheaper than the usual methods. This is a crucial step on the way to developing genome maps available to everyone, which can be part of the medical file of each and every person.
As the scientists begin to produce genetic circuits and artificial molecules in larger numbers, they will also, no doubt, want to package them inside membranes of their own design to produce truly artificial cells in the future. In December 2004, Albert Liebschaver of Rockefeller University in Manhattan described how to make a cell-like system, which he called a "biological reactor in a bubble." The bubble is made of liquid extracted from Escherichia coli bacteria surrounded by a laboratory-made double layer of lipids - very similar to the membrane of a real cell.
The bubbles did not have their own DNA, but they managed to "digest" nutrients that penetrated from the growth medium around them through special proteins in the membrane. Liebshaber sees these bubbles as closed laboratories, which, apart from their future practical uses in chemistry and medicine, could also contribute to understanding how the first natural cells developed.
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