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How do you light a garden?

In an experiment at Berkeley, researchers showed how a simple electric lamp can activate a yeast garden. Researchers hope that the new technology will make it possible to isolate the effect of a single gene in insects and animals as well

Yanai Ofran

Newspaper editors love news that begins with the sentence "The gene responsible for..." has been discovered, but geneticists find it difficult to provide them. Thousands of different genes are operating in every cell at any moment, and it is almost impossible to isolate the effect of one of them. Technology currently being developed at the University of California at Berkeley may make this task easier. All that is required is to aim a lamp at the cell: with the push of a button it will be possible to activate a single garden or disable it from operation.

When they say "laboratory conditions", they usually mean the possibility of isolating the influence of one factor on the system. But when it comes to gardens it is sometimes impossible. Even if cells are grown in a laboratory dish, with the temperature and food precisely regulated, it is difficult to control a single gene. Genes work in intricate networks, so any environmental change affects several genes at once. For years researchers have been trying to develop methods that would allow them to go directly to a certain gene and turn on or off only that one.

One method that has been developed in recent years is the knock-out method - removal of a gene from the genome. Aggressive biochemistry allows researchers to produce a new strain of bacteria, plants, or animals that lack a certain gene. But this method can be very expensive, it requires a lot of time, and above all - it is not always effective. Sometimes after dozens of experiments the researchers discover that the embryos lacking the gene fail to develop. One can conclude from such an experiment that the missing gene is necessary for normal development, but it is difficult to know exactly what its function is.

Biologists continued to dream of a less drastic method. All the methods proposed in recent years are flawed - most of them are very expensive, some of them damage many cellular systems and not just one gene, and they all require a lot of work and time. A team of molecular biologists and plant researchers from the University of Berkeley tried to recruit to the task the mechanisms that the cell itself uses to activate individual genes. Each gene has an activation mechanism - a protein that can bind to it and activate it. The team was looking for a way to control this mechanism.

They borrowed the idea from plants. Plants use light to make sugar. When light enters the plant cell it is supposed to activate the genes that produce sugar. It does this through light-sensitive actuation mechanisms. These mechanisms are essentially a protein molecule with two arms. One arm is a light-sensitive sensor and the other arm is a gene activation mechanism. When the sensor receives light, it activates the activation mechanism, which activates the gene.

The idea of ​​the researchers from Berkeley was simple: disassemble the two arms and attach the light-sensitive sensor to the activation mechanism of another gene. This is how a new molecule is formed. If you want to study a certain gene in a person, plant or bacterium, you only need to locate its activation mechanism and connect the light sensor to it. If light enters the cell, it will hit the sensor, which will activate the activation mechanism - and subsequently the gene.

In an article to be published soon in the journal "Nature Biotechnology", the researchers report on the first successes of the technology. To show that the method works, they attached the light sensor to the activation mechanism of a gene that causes yeast to produce a blue dye. They pointed a lamp at the yeast and within seconds the yeast colony began to turn blue. They also managed to turn off the garden just as easily. Prof. Peter Quill, who participated in the research, claims that the method can work not only in yeast but also in insects and animals. If he's right, it would be a major breakthrough that would allow researchers to turn individual genes on and off with simple electric lamps.

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