Word: rna
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That was fine with Venter, since the strips of DNA that are actually being used as blueprints for constructing a protein are where the action is. So Venter decided to concentrate on these active parts. He focused on the so-called messenger RNA, or mRNA, which ferries instructions from DNA over to the cell's protein-making machinery. This is the essence of the gene, and it was these stripped-down genetic instructions--copied into a more stable form known as cDNA--that he fed into an automated gene sequencer he'd acquired...
Then he had an epiphany: he realized that he didn't need to identify those parts of a cell's genome that code for proteins as long as the cell itself can identify them. Venter switched his attention from the DNA blueprint to the RNA templates the cell makes from those blueprints. His task vastly simplified, he began turning out gene sequences at unprecedented rates...
...gene into the nucleus of a cell? The trick, researchers discovered early on, is to take advantage of the infectious power of viruses; burrowing into cells is second nature to them. A virus is nothing more than a tiny strip of DNA or RNA crammed into a protein envelope. Using the tools of molecular biology, scientists render the virus harmless by deleting some or all of its genes, splicing the therapeutic gene into the remaining genetic material and, in a laboratory Petri dish, mixing it with human cells. The altered virus, now called a carrier or vector, can deliver...
That trial, being conducted by GTI-Novartis in Gaithersburg, Md., uses an ingenious technique to attack brain tumors. After re-engineering a retrovirus--an RNA virus that invades only cells that are in the process of dividing--the doctors outfitted it with a gene from the herpes virus and injected it into the brain. Because virtually the only cells that divide in the brain are tumor cells, the retroviruses infected them alone, inserting the herpes gene into their nuclei. As this gene expressed itself, it made the tumor cells sensitive to the herpes drug ganciclovir. When the drug was then...
Some researchers look forward to the day when gene therapy is used to repair damaged genes. With the new vectors, they would infect cells with small molecules that combine DNA and RNA. These hybrid molecules would seek out and bind to the defective gene, enabling it to function normally. "It would be like a repair mechanism," Wilson explains, "rather than a replacement...