Lack of spring snowpack bodes ill for many A dearth of snow on the ground can

do more than just bum out skiers and snowmobilers. In areas that depend on snowmelt for fresh water, insufficient snowpack can lead to dry soil condi- tions, decreased crop production, and widespread wildfires.

If newly released satellite data are any indication, large portions of the already dry northern and western United States are in for another tough year. Images taken by a NASA satellite launched in December confirmed last week that the northern United States had much less snow cover than average this spring, which followed North America’s warmest winter on record.

Although portions of the Rocky Moun- tains were still topped with snow during early March, only scattered areas from the Pacific Northwest to New York were covered with the white stuff. The images from space show large snowfree areas ex- tending well into the Canadian provinces of Saskatchewan and Manitoba.

Dorothy K. Hall, a senior research sci- entist at NASA’s Coddard Space Flight Center in Greenbelt, Md., presented the findings July 26 at the International Geo- science and Remote Sensing Symposium in the perennially snowless Honolulu.

The smaller March snowpack could be aggravating drought conditions from the

Midwest to the Rocky Mountains, Hall says. After all, she adds, up to 75 percent of the yearly supply of surface water in the western United States comes from snowmelt.

Satellite data collected since the mid- 1960s show that this spring’s snow cover across North America was among the low- est in the past 30 years, says Alan N. Basist, a research meteorologist at the National Climatic Data Center in Asheville, N.C.

The lower-than-average snow cover continues a trend that stretches back to the late 1980s, says David A. Robinson, a climatologist at Rutgers University in Pis- cataway, N.J. This extended snow drought follows a period from the late 1960s to the mid-1980s during which North America’s spring snow cover was more extensive than average, Robinson notes.

Scientists don’t know whether the re- cent trend toward less snow cover in spring is due to a decrease in the overall amount of accumulation or to an increased patchiness in the snow’s distribution.

“It’s probably yes on both counts,” says Robinson. He explains that bare patches of ground, which typically ab- sorb from 80 to 90 percent of the solar ra- diation that hits them, can create pock- ets of heat that accelerate the loss of snow over larger areas.

Robinson says other factors, such as

virus boosts fat in chickens and mice Sniffling and sneezing, pinkeye, and di-

arrhea are bad enough. Now, extra body fat? The growing litany of indignities caused by adenoviruses, a set of norrnal- ly nonlethal but annoying pathogens, a p pears to be takjng an unusual direction.

Researchers at the University of Wisconsin-Madison report in the Au-

that chickens and mice injected with Ad-36. an adenovirus that causes colds in people, have more body fat than un- infected animals.

After 5 weeks, chickens infected with Ad-36 didn’t actually weigh more than uninfected ones. But they had signifi- cantly more body fat, less body protein, and lower blood concentrations of cho- lesterol and triglycerides than control chickens did. Mice receiving an Ad-36 injection were significantly heavier and had 35 percent more body fat than unin- fected mice did.

In both chickens and mice, pronounced changes occurred in the amount of ab- dominal padding known as visceral fat. Compared with controls, there was 67 percent more of this padding in infected mice and more than twice as much in in- fected chickens. Intriguingly, infected an- imals didn’t consume more food.

gust INTERNATIONAL JOURNAL OF OBESITY

AUGUST 5,2000

Ethical considerations precluded the scientists from infecting people with adenovirus, but the team examined the blood of obese and nonobese volun- teers for the presence of antibodies to Ad-36. These markers of past exposure appeared more frequently in the obese group. Furthermore, as with the experi- mental animals, obese people with the antibodies had lower cholesterol and triglyceride concentrations than did obese people without the antibodies. Blood concentrations of antibodies to other adenovirus strains didn’t differ be- tween the two groups.

Anthony Comuzzie of the Southwest Foundation for Biomedical Research in San Antonio calls the study intriguing. “It’s perplexing but interesting,” he says. Too often people dismiss obesity as a matter of food intake, he says, but “we know there are real genetic contribu- tors.” And genetic expression, he notes, can be affected by pathogens. So, he says, “a viral interaction is completely plausible.”

The viral hypothesis is “radical” but worthy of consideration, says Barbara Corkey, director of the obesity research center at the Boston Medical Center in Massachusetts. Until recently, she says,

SCIENCE NEWS, VOL. 158

White depicts regions covered by snow this year between March 5 and 12. The red and yellow lines, respectively, represent average snow lines for March and February over the past 34 years. Gray areas were blocked by clouds during satellite passes.

long-term changes in the springtime weather patterns that carry warm air northward, also could be causing the snowpack to succumb prematurely.

It’s too early to tell whether the recent trend of early snowmelt results from global warming or natural variability in climate. Says Robinson: “That’s where I wish we had a thousand years of climate records, instead of just a couple of decades of satel- lite data and a century or so of weather station measurements.” 4. Perkins

most scientists considered similarly radi- cal the idea that gastric ulcers are caused by Helicobacter pylori infection rather than an unhealthy lifestyle. Now, the mi- crobeulcer link is widely accepted.

Nikhil Dhurandhar, the new paper’s lead author, is currently at Wayne State University in Detroit studying the para- doxical lowering of cholesterol that ac- companies Ad-36 infection. He hopes to discover whether the virus decreases production of cholesterol-a health-pre moting change-or only moves it from the blood into harmful deposits in the arteries and heart.

Dhurandhar is also searching for the mechanism that parlays viral infection into the observed bodily changes. It’s possible that the virus alters metabolic rate, he says, but his preliminary stud- ies suggest that, instead, Ad-36 increas- es the rate at which precursor cells ma- ture into fat-storing cells.

In the long term, Dhurandhar says, he’d like to investigate the possibility of using antiviral drugs and vaccines to treat human obesity. He is also explor- ing whether the other 49 types of hu- man adenovirus promote obesity. Most of these, however, are less likely to play that role than Ad-36 is says Dhurandhar, and “we have our hands full with one virus .“ -R. Bennett

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