Originally created 06/19/97

Health capsules: Something big was brewing eons ago in yeast's genome



Good genes

Beer isn't usually thought of as a symbol of highly evolved life forms. But a tall, cold one might never have come about if not for a major evolutionary event in yeast.

In a report in the latest issue of the journal Nature, researchers from the University of Dublin in Ireland suggest that yeast became good at fermentation because its genetic blueprint was duplicated 100 million years ago.

Some genes in the yeast come in pairs that could best be explained if the genome had doubled. Since then, the scientists said, some duplicate genes have been lost. The ones that remain, most of which have been modified over the years, might be the reason the yeast is so good at producing alcohol.

Disease carriers

Houseflies may play a part in the spread of Helicobacter pylori, a bacterium known to cause most stomach and duodenal ulcers, researchers say in a study published in the June issue of the Journal of Clinical Microbiology.

Flies may initially come into contact with the bacterium by feeding on the feces of infected humans, suggested the scientists from St. Elizabeth's Medical Center in Boston. Then the flies, which can travel up to 20 miles, may go on to contaminate food in supermarkets, homes and anywhere else food is exposed.

Flies have been shown to transmit other disease-causing organisms, including salmonella.

Fresh breath

Rats with lung damage that mimics emphysema were able to build healthy new lung tissue after being given retinoic acid, a derivative of vitamin A.

Scientists at the Georgetown University School of Medicine reported in the journal Nature Medicine that retinoic acid returned damaged small lung sacs called alveoli to normal size and number.

Although the findings are preliminary and further research needs to be done on possible therapies for humans, this is the first time that anyone has identified a means of reversing emphysema, researchers said.

Deforming yeast

Scientists are tracking a new class of infections caused by proteins, which do not carry genes, and think they might be the cause of mad cow disease and similar human disorders.

They have long believed that infections can only be caused by organisms such as viruses and bacteria that contain genetic material. The latest findings, reported in the journal Cell by a team of University of Chicago researchers, show that an abnormal yeast protein called sup35 is capable of deforming other proteins.

These infectious, destabilizing proteins, called prions, are thought to cause mad cow disease, sheep scrapie and human disorders that include Creutzfeldt-Jakob disease and kuru.

Multi-use oil

For years, chemists have processed vegetable oils to make them less harmful to eat or give them a longer shelf life, but now researchers have applied genetic techniques to change the way plants produce the oils in the first place.

Biochemists at Brookhaven National Laboratory and at Sweden's Karolinska Institute have genetically altered a plant enzyme called desaturase to slightly change the oil.

The change may lead to crops used to make nonrenewable petroleum products, researchers said. A bigger demand for a certain industrial material could be met by larger crops.

Hold that thought

A new treatment for schizophrenia appears to also improve patients' short-term memory, researchers reported in the June issue of the American Journal of Psychiatry.

Antipsychotic drugs primarily target outward symptoms of the disease, including hallucinations and delusions. But a team of scientists from the University of California in Los Angeles says that a new medication called risperidone appears to ease other symptoms.

In particular, the drug improves verbal working memory, used to temporarily hold information - the type of memory used to remember a telephone number from directory assistance long enough to dial it.