Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Early exposure to common weed killer impairs amphibian development

18.04.2008
Study results indicate a larger range of harmful consequences

Tadpoles develop deformed hearts and impaired kidneys and digestive systems when exposed to the widely used herbicide atrazine in their early stages of life, according to research by Tufts University biologists.

The results present a more comprehensive picture of how this common weed killer – once thought to be harmless to animals -- disrupts growth of vital organs in amphibians during multiple growth periods.

In recent years, worldwide amphibian population declines have fueled concerns over the potentially harmful effects of pesticides on "sentinel" organisms. Previous research had revealed negative effects of atrazine on amphibians extremely early and late in development. The Tufts study, published in the February 2008 edition of "Environmental Health Perspectives," examined tadpoles during an often overlooked period of development, organ morphogenesis.

Study Results Broadens Knowledge of Herbicide's Effects During a Vulnerable Stage

Organ morphogenesis is a brief, extremely sensitive phase in the tadpoles' growth cycle when they are starting to develop organs, noted Kelly A. McLaughlin, Associate Professor of Biology and lead researcher in the study. She explained that experiments were designed to broaden the understanding of how chemicals affect biological growth in amphibians over multiple stages of development. A $5,000 Tufts University Faculty Research Marshall Grant helped fund the study.

"Amphibians are very vulnerable to contamination since atrazine is used in the same environs where they live and breed," McLaughlin said.

Atrazine is used to control broadleaf and grassy weeds on golf courses and residential lawns, according to the Federal Environmental Protection Agency. Farmers use it to treat corn and soybeans. Atrazine blocks photosynthesis once it is absorbed by plants. Chronic exposure to the herbicide during metamorphosis altered amphibian gonadal development, according to previous research.

To study the consequences of atrazine exposure during organ morphogenesis, McLaughlin and her colleagues, Professor of Biology J. Michael Reed, doctoral candidate Jenny R. Lenkowski and Lisa Deininger, a Summer Scholars program undergraduate student, collected eggs from adult female frogs and then fertilized them in vitro. Scientists exposed the developing tadpoles to 10, 25 and 35 mg/L of atrazine. The 35 mg/L dosage simulated the average amount of herbicide used when it is applied in the field, said McLaughlin.

Multiple Impacts

Twelve to 24 hours after exposure to atrazine, tadpoles were examined for abnormal heart growth, visceral hemorrhaging, intestinal coiling, edema and apoptosis (normal cell death that is "programmed" by the body).

Compared with control populations, the tadpoles that were exposed to atrazine had a dramatically higher incidence of abnormalities. The degree of deformities generally corresponded to the size of the dose. After 48 hours of exposure, the point at which organ development is disrupted most profoundly, 57 percent of the tadpoles exposed to 35 mg/L of atrazine had hearts that were smaller than normal, compared with 2% to 3% for the two control groups.

Ectopic Cell Death

The Tufts scientists also examined atrazine exposed tadpoles for increased incidence of apoptosis by measuring levels of active caspase-3 in the pronephric kidney and midbrain. Caspase-3 is a protein needed for apoptosis to occur. They conducted measurements after 6, 12, 24 and 48 hours of exposure in tadpoles exposed to 25 and 35 mg/l of atrazine. Researchers observed that the atrazine-exposed tadpoles showed significant increases in caspase-3 levels in the kidney and midbrain at 12 hours and beyond when compared with controls. The findings indicated a high incidence of ectopic, or abnormal, apoptosis.

"The increased levels of apoptosis in the midbrain and pronephric kidney we observe suggest that atrazine may cause tissue malformation by inducing ectopic programmed cell death, either directly or indirectly through a mechanism that has not been identified," wrote the researchers.

McLaughlin and her team hope that their findings will lay a foundation for further research to determine the underlying mechanism by which atrazine exposure can affect so many different organ systems during the same stage of early development.

"Our work here documents that atrazine affects amphibian's early development, so the second question is how is this happening?" she said. "We know it blocks photosynthesis in plants but why does it have such negative impact on amphibians?"

Tufts University, located on three Massachusetts campuses in Boston, Medford/Somerville, and Grafton, and in Talloires, France, is recognized among the premier research universities in the United States. Tufts enjoys a global reputation for academic excellence and for the preparation of students as leaders in a wide range of professions. A growing number of innovative teaching and research initiatives span all Tufts campuses, and collaboration among the faculty and students in the undergraduate, graduate and professional programs across the university's schools is widely encouraged.

Alex Reid | EurekAlert!
Further information:
http://www.tufts.edu

More articles from Studies and Analyses:

nachricht Real-time feedback helps save energy and water
08.02.2017 | Otto-Friedrich-Universität Bamberg

nachricht The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>