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May 5, 2009 | 3
Ants are notoriously efficient in their undertaking, carrying off their dead nestmates before the corpses can infect the colony with their pathogens. But how do the worker ants responsible for shuttling their deceased comrades' bodies out of the nest tell live ants from dead?
Some researchers had hypothesized that ants were able to detect breakdown products in decomposing bodies, but a new study in this week's online edition of the Proceedings of the National Academy of Sciences USA contends that the mechanism is just the opposite: While alive, ants produce chemicals that signal their vitality, signals that quickly vanish on death. In other words, deceased ants are identified by the absence of signs of life—a sort of chemical pulse falling silent—rather than the presence of signs of death.
Apr 29, 2009
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A 22-month-old boy has died in Houston from swine flu as the outbreak continues to expand in the U.S. and abroad, the Centers for Disease Control and Prevention (CDC) reports today. This is not the first time swine strains of influenza have claimed lives in the U.S., but previous cases appear to have occurred primarily in people exposed to sick pigs.
The total number of confirmed human cases of the new swine flu strain in the U.S. has now reached 91, according to the CDC Web site: 51 in New York City, 14 in California, one in Arizona, one in Indiana, two in Kansas, two in Massachusetts, two in Michigan, one in Nevada, one in Ohio, and 16 in Texas. The Texas tally includes three teenagers from Guadalupe County and two small children and a 24-year-old in Dallas County, according to Emily Palmer of the Texas Department of State Health Services.
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