A recent study by Harvard researchers on genetic growth patterns has revealed how carcinogens destroy cells inhabited by a virus. Mark S. Ptashne, professor of Biochemistry and Molecular Biology, explained the mechanism by which the phage lambda, a parasitical virus, grows relentlessly when exposed to cancer-causing agents and eventually destroys its host cell, Ptashne said yesterday.

However, Ptashne said the discovery of the source of uncontrolled growth in bacteria does not explain how cancerous cells multiply in humans.

Under Control

Research on genetic growth patterns of the virus might help scientists understand the process of gene control in humans, Ptashne added.

The DNA molecule in the phage lambda either remains dormant or grows uncontrollably when exposed to a car-cinogen, Ptashne said.

About three months ago he discovered that two proteins of the virus bind to the host cell's DNA and determine the cell's growth pattern. One protein activates the genes that trigger destructive growth, while the other, the repressor protein counteracts the growth.

The Harvard researchers concluded that carcinogens split repressor proteins in two, eliminating resistance to destructive growth, Ptashne said.

Last month, Ptashne announced that he had induced sythesis of a protein in a virus by using DNA. The Harvard research group applied the technique developed in the synthesis experiments to their investigation of the genetic role of the two proteins in the phage lambda. "It's all come together in the last several months," Ptashne said.