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Sex Reversal In Frogs ­An Effect Of Drugs In The Environment

Date:
February 28, 2007
Source:
Uppsala University
Summary:
Frogs are more sensitive to hormone-disturbing environmental pollutants than was previously thought. Male tadpoles that swim in water with relevant levels of such substances become females, according to a new study from Uppsala University that will be published in the scientific journal Environmental Toxicology and Chemistry (ET&C) in May.

A small frog of the species Rana temporaria.
Credit: Image courtesy of Uppsala University

Frogs are more sensitive to hormone-disturbing environmental pollutants than was previously thought. Male tadpoles that swim in water with relevant levels of such substances become females, according to a new study from Uppsala University that will be published in the scientific journal Environmental Toxicology and Chemistry (ET&C) in May.

A great number of medicines that humans take are released through waste waters and end up in nature. The contraceptive pill estrogen ethynylestradiol has been found in waters in many countries, and this has been linked to disturbances

in reproduction in wild fish. Researcher Cecilia Berg and doctoral candidate Irina Pettersson at the Department of Environmental Toxicology, Uppsala University, have shown that low, environmentally relevant concentrations of this substance cause sex reversal in frogs.

“This is the first clear evidence that estrogen in nature really can have a detrimental effect on frogs. Previous studies have used considerably higher concentrations than are normally found in nature,” says Cecilia Berg.

When tadpoles swim in water with low concentrations of ethynylestradiol, all of them develop ovaries instead of what is the normal process, namely, that half of the frogs develop ovaries and the other half testicles. The research team has shown this in two species of frogs, the common frog (Rana temporaria) and the African clawed frog (Xenopus tropicalis). It is during the tadpole stage that

reproductive organs begin to develop in frogs, a process that is regulated by the hormone system.

“Our findings show that frogs are more sensitive to hormone-disrupting environmental pollutants than we previously thought,” says Cecilia Berg.

These findings will be published in ET&C in May.


Story Source:

The above story is based on materials provided by Uppsala University. Note: Materials may be edited for content and length.


Cite This Page:

Uppsala University. "Sex Reversal In Frogs ­An Effect Of Drugs In The Environment." ScienceDaily. ScienceDaily, 28 February 2007. <www.sciencedaily.com/releases/2007/02/070228091721.htm>.
Uppsala University. (2007, February 28). Sex Reversal In Frogs ­An Effect Of Drugs In The Environment. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2007/02/070228091721.htm
Uppsala University. "Sex Reversal In Frogs ­An Effect Of Drugs In The Environment." ScienceDaily. www.sciencedaily.com/releases/2007/02/070228091721.htm (accessed July 28, 2014).

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