Tobacco Lights Up, Providing a Method for Tracing Genes
Scientists at the University of California, San Diego, have fused the gene that lights fireflies to a tobacco gene in an experiment that has produced a plant that glows in the dark and may illuminate the way toward greater understanding of the basic units of heredity.
The experiment was described Thursday as the first step in creating a powerful tool to visually trace the behavior of genes--the building blocks of heredity--in plants and animals.
The research could lead to development of better drugs and disease-resistant crops. It also could be adapted for diagnostic tests to detect diseases in humans--tests that now require radioactive tagging, scientists said.
The key element involves use of the substance that lights up fireflies as a visual tracer. UC San Diego scientists said Thursday that they have successfully placed the gene that lights up fireflies into tobacco plants.
A six-member research team fused the firefly’s so-called “lantern,” a gene that produces an enzyme known as luciferase, with the gene of a common plant virus and then grew the composite gene in the laboratory. Through gene-splicing technology, they inserted the new gene into tobacco plant leaves and were able to grow plants that have the fused gene virus in their cells.
When the particular gene actively “turns on,” or expresses itself, the firefly gene lights up as well, and the gene activity can be detected and measured by scientists. The particular virus used in initial experiments is a gene that is active most of the time, so scientists were consistently able to detect light throughout the tobacco 1886151022Stephen H. Howell, a collaborator on the project.
As a genetic marker, the firefly gene should allow scientists to trace any targeted gene, molecular geneticist Donald R. Helinski, a second team member, said at a news conference here. Scie1853122931plant genes dealing with disease, growth, drought resistance or other activities, he said.
Researchers would then measure the subsequent light source through a number of generations to follow its inheritance characteristics. The specimens would not have to be destroyed to learn what happens, as is necessary now in gene research.
“It’s a powerful aid,” Helinski said, “allowing measurements to get at the question of whether a gene is turned on at the right time, in the right tissue (for best performance), and to (then) measure modifications of the gene to see if there is improvement.”
Howell added: “To understand how genes are turned on and off during the course of development and in what context is very important. The tissues in our own bodies become different from one another because certain constellations of genes are turned on and off in specific parts of the body. The same holds true for plants.”
Low-Level light
University scientists used the tobacco plant because it is a model plant system, used as rats are used in animal research. In the tobacco plant experiment, the firefly light was detected and measured by simple X-ray film exposure as well as by more elaborate devices. An additional organic substance called luciferin, needed to activate the firefly gene, was added to the plant through watering. The plant’s luminescence is low-level and can be seen with the naked eye only dimly in a darkened room.
The firefly gene is already being made available to laboratories at other universities and to private companies, at a nominal fee. UC San Diego has applied for a patent on firefly gene application.
UC San Diego scientists have already begun experimenting with the firefly gene in monkey and mouse cells. In addition, biochemist Marlene Deluca, who cloned the firefly gene last year along with Helinski, said the enzyme could be used as a tracer in diagnostic substances passed through the human body to detect diseases. Her lab is working on developing such tests.
