Advertisement

A Scientific Race: Recombining DNA

"When people are doing things similar enough so they can talk with one another," Gilbert says, "they are doing things where they can compete." He feels that it is important for the groups to pursue the same aims independently, saying, "There is no way of knowing which way is better."

A Different Drummer

Work marches to the speed of a different drummer for Helga Doty, a senior research associate in Biochemistry, and her coworkers, who have also begun working in the P-3 laboratory at the Biolabs. Doty's group is tackling the vast problem of how genes are turned on and off--using gene splicing as a research tool rather than an end in itself. She has been studying RNA--one of the intermediate steps the cell employs in translating the DNA code--for 22 years. Whereas Gilbert has a definite medical goal pushing him on, Doty must stab in the dark and hope to come up with a lead which will help scientists to understand this most basic of cellular processes.

Scientists believe that signals in the DNA code itself regulate which genes will be read and translated into protein. So Doty and other researchers are interested in determining what DNA sequence changes accompany changes in production levels of the proteins. "One has to have a probe that is either highly specific or easily labeled," according to Doty. This is where plasmids and genetic engineering comes in. Once a DNA segment is inserted into a bacterial plasmid, the researchers can grow up a supply of it "overnight." This may be used to identify complementary copies of RNA and to determine where sequence changes occur.

"It's just a fantastic and powerful tool," Doty says. This method of including E. coli to clone many copies of the DNA template is cheap, efficient, and, above all, it produces pure mixtures of the DNA. Despite gene splicing abilities, which may speed up the work by years, Doty says without any hint of discouragement, "disecting out what any of this means is going to take a tremendous amount of time."

Advertisement

Says Gilbert, "The actual contribution to knowledge is not so narrow that if you don't make it on day one you've lost (a race). There will be ancilliary knowledge that just comes out."

Gene splicing is a technique for recombining genetic material in which the tape is DNA, a molecule which codes in a four-letter alphabet for the various proteins which are vital for the, functioning of every cell. Researchers use a chemical scalpel--restriction enzymes--which attack DNA at specific sites, breaking it and exposing two "sticky" ends to which a new piece of DNA--a gene--can be attached.

Genes from other organisms [3] are inserted into the DNA of E. coli bacteria which copies and decodes DNA rapidly. A ring of DNA--a plasmid--which is transferred between bacteria, is used for the incorporation procedure. It is easily isolated from a bacterial cell [1], cut open [2] and used as a receptor for a foreign gene [4]. The plasmid then carries the inserted DNA into a cell [5] where many copies can be "cloned."

Advertisement