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Tuesday, April 3, 2012

Herbicides Can Induce Morphological Changes in Vertebrate Animals

Roundup, the world’s most popular weed exterminator can induce morphological change in a vertebrate animal. In a new study published in the Ecological Applications journal by Rick Relyea of University of Pittsburg shows that application of Roundup caused two species of amphibians to alter their morphology.

Relyea set up tanks of simple wetland communities containing leaf litter, algae, zooplankton and three species of tadpoles: wood frogs, leopard frogs and American toads. Some tanks contained caged predators i.e. dragonflies. Tadpoles were added to each tank and then exposed to a range of environmentally relevant herbicide concentrations of Roundup.

The tadpoles were removed from the tank after 3 weeks. The presence of dragonfly predators released chemicals known as kairomones, which induce defenses in the prey – larger tadpole tails. The ability to modulate development in the presence of predators is called predator-induced polyphenism.

The most intriguing finding of this study is that Roundup also induced development of larger tadpole tails. The similar morphological changes when exposed to Roundup suggest that the broad-spectrum herbicide may interfere with the hormones of tadpoles and potentially many other animals. These findings suggest that unchecked, application of herbicides may have far-reaching effects on non-target species, including humans, than previously thought.

In 1968 Waddington coined the term epigenetics, which is now defined as genetic mechanisms that create phenotypic variation without the base-pair nucleotide sequence of the genes. Epigenetic research is currently focusing on the mechanisms of phenotypic plasticity and on how changes in gene expression patterns mediated by the environment can cause diseases such as cancers and hypertension.

See full article: Rick A. Relyea. New effects of Roundup on amphibians: Predators reduce herbicide mortality; herbicides induce antipredator morphology. Ecological Applications Volume 22, Issue 2 (March 2012) pp. 634-647

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