Pet fish face a rough ride when shipped from their home waters to aquariums around the world. To stave off infection, antibiotic use is widespread in the ornamental fish industry. But the practice is proving increasingly ineffective and contributes to antibiotic resistance in these ornamental fish, according to a study published this month in the Journal of Fish Diseases. Scientists studied the bacteria within 32 species of freshwater fish that were imported from Singapore, Colombia and Florida, the major hubs for ornamental fish export. They found nine bacterial species that were not susceptible to any of the antibiotics tested. The most effective antibiotic had 16 percent resistance. The least effective drug faced 77 percent resistance. Though the health risks to humans remains low, the bigger problem is that the $15 billion ornamental fish industry will face a growing challenge treating diseased fish as antibiotics remain unregulated. Researchers plan to use this information to educate fish farmers on the need to curb the blanket use of antibiotics in fish feed.
Planet cools off own sun
What do you do if you're a hot Jupiter and want to cool off? Why, you use your gravity to lift up the surface of your sun, cooling it and creating a dark spot on the star. In The Astrophysical Journal Letters, astronomers report using the Kepler spacecraft to observe the brightness of a star in the constellation Cygnus more than a million times. Named HAT-P-7, this star has a hot Jupiter -- a giant planet orbiting close-in. The world's gravity raises the star's surface away from its hot centre, causing part of the surface to cool by just a fraction of a degree Kelvin and produce a dark spot that lags behind the planet's position by a few hours. If confirmed, this discovery is the first time astronomers have ever seen planet-induced "gravity darkening" and demonstrates Kepler's remarkable ability to detect even the subtlest of stellar signals.
Another weapon against depression
Blocking a protein in the brain that prevents neural stem cells from maturing may lead to a potential new way to treat depression, one of the most common mental disorders in the United States.
After the gene that makes the protein, called sFRP3, was deleted in mice their brains behaved as though they were on antidepressants, researchers from Johns Hopkins University in Baltimore found. When sFRP3 is overactive, neural stem cells can't mature into neurons, a process that's been linked to the success of antidepressant treatments, according to the study published Thursday in the journal Cell Stem Cell.
-- From the wire services