Molecular study shows unexpected effects of toxin

Aug 08, 2011

Scientists from the University of Birmingham studying the effects of the widely-used pesticide fenitrothion, have discovered unexpected cell damage in a common freshwater fish, roach, exposed to the toxin.

With colleagues from the universities of Exeter and Sussex the researchers exposed male roach to the pesticide for 28 days then studied the in their . Metabolites include fats, sugars and thousands of other – substances that can indicate whether a cell is healthy.

The results did not show the expected of fenitrothion on the roach, but revealed a host of other effects, including changes to the way steroids are metabolised. This suggests that fenitrothion is an endocrine disruptor – a so-called gender-bender which can affect an organism's sexual characteristics.

The work reveals the range of effects this kind of exposure can have on non-target organisms, and it could help scientists develop effective 'environmental biomarkers' or indicators that show when toxic substances have found their way into the wider environment.

This area of research – called metabolomics – has developed over the last decade as a new way of investigating the links between metabolic changes and an organism's health – for example, measuring cholesterol can provide an indication of heart disease in humans.

'It's a discovery technique,' says Professor Mark Viant from the School of Biosciences at the University of Birmingham, one of the lead authors of the report, published in Environmental Science & Technology. 'Instead of measuring just one molecular response to a , in metabolomics you measure many hundreds of metabolites and get much more and richer information about what's actually going on inside a cell in response to external stress.’

Surprisingly fenitrothion appeared not to have the expected neurological effects on the roach – in fact the opposite seemed to be the case. Instead of an increase in the chemical acetylcholine, which responds to the toxin's neurological action, the researchers saw a significant decrease.

And they found a range of other molecular responses in the fish, in particular in energy metabolism as well as unexplained effects on the metabolism of the amino acid phenylalanine, which the body uses to create proteins.

The unexpected neurological changes could mean the fish adapted to the presence of the pesticide. If this is the case it could be good for the roach, as it means they've developed a way of dealing temporarily with the primary mechanism of the toxin.

But such adaptation could come at a cost, as it may use energy that would otherwise be invested in growth and reproduction.

'We don't know yet whether this is what happened,' says Viant. 'But we do know that the energy levels in the fish were affected.'

The Environment Agency classifies fenitrothion as a 'red list' pollutant, one of the most dangerous substances to the aquatic environment. Once used on crops it can be washed off the soil and find its way into surface water.

'But our purpose wasn't purely to discover the toxic effects of fenitrothion,' Professor Viant explains. 'The point was to evaluate this still relatively new technique as a tool for discovering novel biochemistry and environmental biomarkers.'

The report highlights the complexity of the roaches' response to the toxin. Viant emphasises that a more traditional investigation, purely to check for the expected neurological effects on acetylcholine in the roach, would have turned up counterintuitive results that revealed nothing about the wider effects of the toxin.

'We need to be careful not to make simple assumptions about how organisms will respond to environmental stress,' he concludes.

The advantage of this metabolomics approach is that these metabolic changes happen long before the organism's health is compromised, so potentially the technique could be used to detect harmful effects of toxins and other environmental stresses and do something about them before it's too late.

Explore further: Stanford researchers rethink 'natural' habitat for wildlife

More information: dx.doi.org/10.1012/es103814d

Provided by University of Birmingham

not rated yet

Related Stories

Recommended for you

Plants with dormant seeds give rise to more species

Apr 18, 2014

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Scientists tether lionfish to Cayman reefs

Apr 18, 2014

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

User comments : 0

More news stories

Biologists help solve fungi mysteries

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.