Arsenic and new rice

June 10, 2008

Amid recent reports of dangerous levels of arsenic being found in some baby rice products, scientists have found a protein in plants that could help to reduce the toxic content of crops grown in environments with high levels of this poisonous metal. Publishing in the open access journal BMC Biology, a team of Scandinavian researchers has revealed a set of plant proteins that channel arsenic in and out of cells.

Arsenic is acutely toxic and a highly potent carcinogen, but is widespread in the earth's crust and easily taken up and accumulated in crops. Contaminated water is the main source of arsenic poisoning, followed by ingestion of arsenic-rich food, especially rice that has been irrigated with arsenic-contaminated water. According to the WHO, arsenic has been found approaching or above guideline limits in drinking water in Argentina, Australia, Bangladesh, Chile, China, Hungary, India, Mexico, Peru, Thailand, and the US.

Until now, scientists have been unable to identify which proteins are responsible for letting arsenite, the form of arsenic that damages cellular proteins, into plant cells. Now Gerd Bienert and his colleagues from the University of Copehangen, Denmark and the University of Gothenburg, Sweden, are the first to show that a family of transporters, called nodulin26-like intrinsic protein (NIPs), can move arsenite across a plant cell membrane. NIPs are related to aquaglyceroporins found in microbes and mammalian cells and which have already been shown to function as arsenite channels in these other organisms.

Bienert's team put the plant genes coding for different NIP transporters into yeast cells in order to test the cells for arsenic sensitivity. The researchers found that the growth of yeast containing certain plant NIPs was suppressed when arsenite, one of the predominant forms of arsenic found in soil, was added to the mix. They showed that the arsenite was channelled by NIPs and accumulated inside the yeast cells. Further investigations showed that only a subgroup of NIPs had arsenite transport capabilities, and have now been identified as metalloid channels in plants.

More surprisingly, the researchers also found that when they added arsenate some yeast, cells actually grew better and arsenite was released out of the cells. "It appears that some NIPs don't just transport arsenite in one direction", says Bienert. "They are bidirectional and, given the right conditions, can clear cells of toxic arsenite as well as accumulate it. This striking exit of the accumulated arsenite in cells could have an important role to play in the detoxification of plants, especially coupled with possibility of engineering a transporter that discriminates against arsenite uptake in the first place."

Source: BioMed Central

Explore further: Gene critical to the development of low arsenic plants identified by scientists

Related Stories

Scientists solve mystery of arsenic compound

October 13, 2010

Scientists have solved an important mystery about why an arsenic compound, called arsenite, can kill us, and yet function as an effective therapeutic agent against disease and infections.

Arsenic hyperaccumulating ferns: How do they survive?

June 8, 2010

Arsenic is toxic to most forms of life, and occurs naturally in soil and ground water in many regions of the world. Chronic exposure to arsenic has been linked to lung, bladder and kidney cancer, and thus there are strict ...

Destructive enzyme shows a benevolent side

January 10, 2007

New research shows that a recently discovered enzyme that destroys the messenger RNA (mRNA) for some proteins can also help to protect the mRNA during times of stress. The response might help cancer cells survive chemotherapy ...

Sheltering Of Messages May Help Cancer Cells Defeat Therapy

November 27, 2006

New research has discovered that cells protect rather than destroy the message molecules needed to make certain proteins during periods of stress. The response might help cancer cells survive chemotherapy and radiation therapy.

Recommended for you

Ancient genome from Africa sequenced for the first time

October 8, 2015

The first ancient human genome from Africa to be sequenced has revealed that a wave of migration back into Africa from Western Eurasia around 3,000 years ago was up to twice as significant as previously thought, and affected ...

On soft ground? Tread lightly to stay fast

October 8, 2015

These findings, reported today, Friday 9th October, in the journal Bioinspiration & Biomechanics, offer a new insight into how animals respond to different terrain, and how robots can learn from them.

Blue skies, frozen water detected on Pluto

October 8, 2015

Pluto has blue skies and patches of frozen water, according to the latest data out Thursday from NASA's unmanned New Horizons probe, which made a historic flyby of the dwarf planet in July.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.