Focus
on Research
Penn State Intercom......July
26, 2001
Amphibian mortality linked to global
climate change, research team reports
By Barbara Kennedy
Eberly College of
Science
For
the first time, researchers have identified a direct link between global
climate change and local factors that cause the death of amphibian eggs
in the wild. 
Scientists have been trying to determine why amphibian populations worldwide have been declining at alarming rates since the late 1970s, but their research has pointed to a confusing variety of causes. Now Joseph Kiesecker, professor of biology, reports the research team he leads has shown that global warming causes changes in rainfall patterns, causing stress in moisture-sensitive amphibians, leaving them susceptible to a variety of pathogens. The stresses and resulting causes of death depend on the specific conditions in the animals' local habitat.
Kiesecker's team found a direct link between the Southern Oscillation Index, which tracks temperature fluctuations including the El Niño warming cycles in the South Pacific, and the amount of rain or snow in Oregon's Cascade Mountains. Other team members include Andrew R. Blaustein and Lisa K. Belden of Oregon State University.
"More than 10 years, we have been collecting data at a number of sites in the Cascades, 4,000 to 7,000 feet above sea level, where there are large breeding populations of western toads," said Kiesecker, whose team backpacks for 10 miles to reach some of the remote sites. The researchers work in tents for weeks to build their experimental devices, which include boxes they designed to anchor the toad eggs at different distances below the surface of the lake in order to learn whether a thicker blanket of water better protects the eggs from the damaging effect of ultraviolet radiation. "We have found that water levels are shallower during years when there is less snow, which exposes the eggs to more ultraviolet light and makes them susceptible to disease outbreaks."
"Around the early 1990s, we started to see 80 to 100 percent mortality," Kiesecker said. The toad eggs laid at shallower depths, which are stressed by overexposure to ultraviolet light, are killed by a water-mold pathogen, Saprolegnia ferax, which generally attacks only organisms that are injured or under stress in some way. Kiesecker said ultraviolet light may not be a factor at other sites of amphibian decline, where embryos laid under a heavy vegetation canopy are not exposed to ultraviolet light. Other pathogens have been identified as a cause of death.
"Stress-related disease is the one consistent factor that may link amphibian deaths worldwide, and we have demonstrated that amphibian stress in the Cascades is ultimately linked to recent global climate fluctuations," Kiesecker said.
"This study shows that if we want to understand the complex ecology of the world around us, we must start looking at the big picture, and there may not be simple or easy answers," Blaustein said.
Barbara Kennedy can be reached at bkk1@psu.edu.
Students learn
'how' to say
no
to drugs
As drug abuse continues to take its toll on this nation's youth, teaching students how to say no to drugs is showing positive results, according to a study.
Researchers report that students in the Keepin' it R.E.A.L. project are drawing on their strengths and the strengths of their families and communities to recognize the risks of drug abuse and to learn how to live drug-free lives.
R.E.A.L., an acronym for the four different ways of refusing drug offers -- Refuse, Explain, Avoid and Leave -- was developed to find ways of decreasing adolescent drug use.
"Instead of telling students 'just to say no,' the program's main focus is in teaching students 'how' to say no," said researcher Michael L. Hecht, professor of speech communication.
The R.E.A.L. strategies, social norms and decision-making are at the core of the school-based Drug Resistance Strategies Minority Project, a $3.2 million program funded since 1989 by the National Institute on Drug Abuse. The program was presented to 4,600 seventh-grade students at 35 middle schools in Phoenix, Ariz.
Students were surveyed following the program at nine months and at 18 months. Specifically, the program slowed the rate of increase in eighth-graders' alcohol use by 75 percent per month; slowed the increase in cigarette smoking by 81 percent per month; and slowed the increase in marijuana use by 63 percent per month.
"We learned that the students were less likely to experiment with drugs after completing the program and were more likely to stop, especially drinking alcohol," Hecht said.
Hecht and Flavio F. Marsiglia, associate professor of social work at Arizona State University, are principal investigators of the project. They, along with a multidisciplinary team of researchers and educators in Arizona and Pennsylvania, developed the 10-week, 10-lesson program.
As a result, resistance strategies videos and public service announcements were produced by youths for youths. Billboards in Phoenix proclaimed the Keepin' it R.E.A.L. program in middle schools. The billboards, bumper stickers, television public service announcements, and citywide contests were some of the most visible elements of the drug resistance strategies program. These public statements reinforced the messages that middle-school students learned as well as reaching additional children and parents in the Phoenix area.
Medication shows promise in
treating polycystic ovary disease
An insulin sensitizing agent, trogliazone, shows effectiveness in ameliorating the symptoms of polycystic ovary syndrome (PCOS), a common cause of infertility, according to a recent study.
Dr. Richard Legro, associate professor of obstetrics and gynecology at the College of Medicine at The Milton S. Hershey Medical Center in Hershey, is one of the study's authors. A nationally recognized expert on PCOS, Legro explains that women diagnosed with PCOS do not ovulate and have high androgen (male sex hormone) levels that can cause excess body hair. The disorder affects approximately 4 percent of reproductive-aged women. Currently, therapy is geared toward symptomatic relief that suppresses androgen production and stimulates ovulation. Research conducted by Legro and confirmed by colleagues in his field supports the premise that insulin resistance is a causal factor for the syndrome.
Building on the results of studies that demonstrate a beneficial effect of insulin-lowering agents in treating this disorder, the study group hypothesized that administration of trogliazone would improve ovulatory function and diminish symptoms associated with the syndrome.
This multicenter clinical trial included 305 premenopausal women who had been diagnosed with the syndrome. The women were assigned to one of two treatment arms: either treatment with a placebo or treatment with trogliazone.
Results showed an increase in ovulatory rates for women receiving the trogliazone. Of the women treated with the 600 ml per day dosage, 57 percent ovulated more than 50 percent of the time compared to 21 percent of the women in the group that received a placebo. Hormone levels became more stable in concert with increasing dosage of trogliazone.