06/25/03

Lower-caffeine coffee plants might avoid flavor-robbing processes

Researchers have genetically engineered coffee plants that have 70 percent less caffeine than usual in their leaves.

Scientists at the Nara Institute of Science and Technology in Japan used RNA interference to manipulate the plants, interfering with the gene responsible for an enzyme used to make caffeine.

Experts say a caffeine-free bean would be an improvement over current decaffeination processes, which use water or organic solvents to remove the stimulant from the beans before they are roasted -- removing some flavor and aroma as well.

Whether the plants' beans will have less caffeine won't be known until the plants mature in three or four years, said Shinjiro Ogita, the study's lead author. The Japanese scientists also have not reached the commercial decaffeination level of 97 percent.

The researchers reported their findings in the current issue of the journal Nature. Research finds volume control in dolphins' sonar clicks for prey

Dolphins adjust the volume of their sonar clicks to target prey, according to a study in the current issue of Nature.

Whitlow Au and Kelly Benoit-Bird of the Hawaii Institute of Marine Biology say the volume of the clicks decreases as a dolphin approaches its prey.

Dolphins wait until receiving the echo of their last click before releasing another, the researchers said. As they draw nearer to the target, the echoes arrive sooner, and the click rate increases. As only a certain amount of air is available to generate the clicks, the volume decreases as the rate goes up. Too-enthusiastic tooth brushing just as bad as not quite enough

People who brush their teeth for longer and harder than is necessary may not be making them any cleaner and could be causing permanent damage, a study suggests.

A study using electric toothbrushes, by the University of Newcastle upon Tyne in England, found that when researchers increased the length of people's brushing regime and the pressure on their teeth, the removal of harmful bacteria improved only to a point. Beyond that point, the risk of causing oral health problems, such as abrasion of tooth enamel or gums, increased.

The research, published in the Journal of Clinical Periodontology, found that two minutes and 150 grams (about the weight of an orange) was the optimum time and pressure for the average person's brushing regime. Twelve volunteers took part in the four-week study, which examined 16 combinations of brushing times (30, 60, 120 and 180 seconds) and pressure (75, 150, 225 and 300 grams). The volunteers were trained to use an oscillating electric toothbrush, which was wired to a computer that took time and pressure measurements.

Similar results would be expected if the study was carried out using ordinary toothbrushes, the researchers said. Warmer global climate helps spread vegetation far and wide

A new study using satellite data concludes that the Earth has been greening during the past 20 years as climate warmed.

Researchers reported in the June 5 issue of the journal Science that climate changes have provided extra doses of water, heat and sunlight in areas where one or more of those might have been lacking. Plants flourished in places where climatic conditions previously limited growth.

"Our study proposes climatic changes as the leading cause for the increases in plant growth over the last two decades, with lesser contribution from carbon dioxide fertilization and forest regrowth," said Ramakrishna Nemani, the study's lead author, from the University of Montana in Missoula.

From 1980 to 2000, changes to the global environment have included two of the warmest decades in the instrumental record; three intense El Nino events in 1982-83, 1987-88 and 1997-98; changes in tropical cloudiness and monsoon dynamics; and a 9.3 percent increase in atmospheric carbon dioxide, which in turn affects human-caused influences on climate. All these changes affect plant growth.

Another co-author, Charles Keeling of the Scripps Institution of Oceanography in La Jolla, Calif., said no one knows whether these effects are caused by short-term climate cycles or longer-term global climate changes.

Nemani and colleagues made a global map of the net primary production of plants from climate and satellite data of vegetation greenness and solar radiation absorption. -- Compiled by Richard L. Hill