Genetic engineering between a tree and a firefly
It sounds like a child's riddle: What do you get when you cross a firefly with a tobacco plant? Answer: tobacco that lights itself. That is essentially what a team of scientists at the University of California at San Diego has done. By outfitting a fragment of a plant virus with the gene that tells firefly cells to produce a protein central to generating light, the researchers have created a plant that literally glows in the dark. The technique, reported in last week's issue of the journal Science, is significant not so much as a demonstration of virtuoso genetic engineering, but... The luciferase gene from the firefly, Photinus pyralis, was used as a reporter of gene expression by light production in transfected plant cells and transgenic plants. A complementary DNA clone of the firefly luciferase gene under the control of a plant virus promoter (cauliflower mosaic virus 35S RNA promoter) was introduced into plant protoplast cells (Daucus carota) by electroporation and into plants (Nicotiana tabacum) by use of the Arobacterum tumefaciens tumor-inducing plasmid. Extracts from electroporated celLs (24 hours after the introduction of DNA) and from transgenic plants produce light when mixed with the substrates luciferin and adenosine triphosphate. Light produced by the action of luciferase was also detected in undisrupted leaves or cells in culture from transgenic plants incubated in luciferin and in whole transgenic plants "watered" with luciferin. Although light was detected in most organs in intact, transgenic plants (leaves, stems, and roots), the pattern of luminescence appeared to reflect both the organ-specific distribution of luciferase and the pathway for uptake of luciferin through the vasculaure of the plant.. Luciferase
Luciferase is a generic name for enzymes commonly used in nature for bioluminescence. The most famous one is firefly luciferase (EC 18.104.22.168). In luminescent reactions, light is produced by the oxidation of a luciferin (a pigment), sometimes involving Adenosine triphosphate (ATP) . The rates of this reaction between luciferin and oxygen are extremely slow until they are triggered by the presence of luciferase. The reaction takes place in two steps: luciferin + ATP --> luciferyl adenylate + PPi
luciferyl adenylate + O2 --> oxyluciferin + AMP + light
The reaction is very energy efficient: nearly all of the energy input into the reaction is transformed into light. As a comparison, the incandescent light bulb loses about 90% of its energy to heat. Luciferin and luciferase do not refer to a particular molecule. They are generic terms for a light-producing chemical and its associated regulatory compound, usually a protein. A wide variety of species regulate their light production using a luciferase. The most famous is the firefly, although it even exists in organisms as different as the Jack-O-Lantern mushroom and many marine creatures. In the firefly, the oxygen required is supplied through a tube in the abdomen called the abdominal trachea. Some organisms, notably the click beetles, have several different luciferase enzymes which each can produce different colors from the same luciferin. Luciferase can be produced in the lab through genetic techniques, and has a wide variety of uses. Genes for luciferase can be genetically engineered into organisms so that they glow when exposed to the right luciferin. This allows visualization of certain biological processes, stages of infection, and provides other valuable sources of information. Mice, silkworms, and potatoes are just a few organisms that have already been engineered to produce the chemical. Luciferase can be used in blood banks to determine if red blood cells are starting to break down. Laboratories can use luciferase to produce light in the presence of certain diseases. The possibilities for uses for luciferase continue to expand. One peculiar application of luciferase was when a team of...
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