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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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11 December 1997 6:30 pm
Parasites that cause skin rashes in people and infest ducks can commandeer DNA in the brains of snails and order the unwitting mollusks to give up sex. The findings, in the current issue of the Proceedings of the National Academy of Sciences, suggest that some parasites can enhance their ability to survive by hijacking the controls of specific host genes.
Wormlike creatures named Trichobilharzia ocellata spend part of their life cycle in the flesh of small freshwater snails (Lymnaea stagnalis). Previous studies had shown that snails with the parasites forgo sex, allowing them to grow more rapidly. At the same time, "within 1 1/2 hours of [the parasite] entering the host, gene expression is significantly and selectively affected," says Marijke de Jong-Brink, a neurobiologist at Vrije University in Amsterdam.
Hoping to link these two observations, Jong-Brink's team exposed snails to a parasite-filled bath. They removed the snails' brains after various durations to measure levels of mRNAs, which translate the DNA blueprint into a template for building proteins. In the parasite-ridden snails, mRNA levels shot up, with some mRNA types exceeding by three times the level of those in healthy snails. The parasite may be releasing a chemical, says Jong-Brink, "that stimulates or inhibits special genes in the host central nervous system, either directly or indirectly." These genes are involved in reproduction and growth regulation.
The finding reinforces the view that "parasites--somewhat like viruses--can force their hosts to act to their benefit," says Viktor Mutt, a medical biochemist at the Karolinska Institute in Stockholm. The findings could have implications for a similar species of parasite that causes schistosomiasis, a debilitating disease that threatens one out of six people in some developing countries.