Genetic Engineering — Nature’s Way
Life has been divided into two major groups: Prokaryotes — which are those organisms like bacteria and viruses that exist as single cells without organelles (tiny internal compartments bounded by a membrane), and Eukaryotes - comprising all the higher organisms (from amoebae to humans) that may exist either as single cells or as complex multicellular creatures like humans and whose cells have within them a variety of tiny but important compartments such as nuclei and mitochondria. Such organelles function as partially sealed-off compartments within which important metabolic processes and materials are segregated. More recently, a third category of organisms, called Archaea, has been described which has characteristics shared by both the above groups.
Among the eukaryotes is a single-celled organism named Galdieria sulphuraria. This organism is a member of a family of one-celled red algae that enjoy habitats that are very acid, very salty, and often very hot (up to 130 degrees Fahrenheit). Such habitats exist in volcanic hot springs and in some mining and manufacturing wastes. When such habitats also include high amounts arsenic, mercury and other toxic heavy metals, G. sulphuraria, which appears to have existed for at least a billion years, may be the only organism present. The name commonly applied to an organism capable of surviving and growing in such extreme habitats is “extremophile.”
What makes G. sulphuraria so unusual, aside from its enjoyment of such extreme environments, is its amazing metabolic versatility. It can extract energy from light as plants do, or it can extract energy from carbohydrates (for example, sugars) as we do, thus it can grow in either light or darkness, and it can also thrive with or without oxygen. In spite of its very acidic habitat it also keeps its internal environment at a neutral level of acidity just as our cells do. Most organisms, including humans, would be dead in a matter of minutes in the environments this hardy organism thrives in. For this reason G. sulphuria is a prime candidate for helping us clean up some of our very nasty and dangerous chemical wastes.
Recently, the genome of this remarkable species was sequenced. It was discovered that many of the genes that allow this organism to flourish in hostile environments appear to have come, not from the very slow processes of mutation and natural selection, but by a process called “horizontal gene transfer.” Horizontal gene transfer is what scientists do when they genetically engineer plants and animals such as was done when the gene for a toxin made by the bacteria B. thuringiensis (Bt for short) was inserted into corn to make it resistant to a variety of insect pests. It has been known for many decades that bacteria and viruses are naturally capable of exchanging genes in this way. These mechanisms for rapidly inducing permanent genetic changes in an organism became known as “horizontal gene transfer” in order to contrast it with genetic information transmitted “vertically” from parent to offspring during reproduction. In the case of G. sulphuraria, many of the genes relevant to its ability to survive and multiply under extreme and varied conditions appear to have come from both bacteria and fungi, and perhaps even some from viruses, by means of horizontal gene transfer. Thus genetic engineering has been a process known to nature millennia before we humans mastered the necessary techniques.
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