You go to sleep at night, you wake up in the morning—the definition of sleep doesn’t seem so complicated. But start asking questions and things start getting thorny: Are dolphins that never stop swimming sleeping? Are migrating birds that “shut down” half their brains sleeping? Is someone under general anesthesia sleeping? And what about babies in the womb?
Unborn human babies in the womb are pretty difficult to monitor 24/7, so the researchers interested in that last question got ahold of unhatched chicken eggs. In a new Current Biology paper, they report that chicks show higher-brain activity patterns similar to sleep, and the cries of a hen could “wake up” the chick even when other loud but not chicken-salient sounds could not. These higher-brain activity patterns only appear in the last stage of incubation, presumably after their brains become well developed.
To monitor brain activity in the chicks, the scientists carefully made a small hole in the top of the egg and injected radioactive sugars onto the egg’s inner membrane. The developing embryo absorbed these sugars, which the team could then track with a PET scan. Active neurons need energy, which they get from sugar, so mapping the radioactivity in the brain shows what parts of the brain are active.
Though the swine flu scare of 2009 may have bumped the avian variety of flu from of the popular imagination, biomedical researchers certainly haven’t forgotten the potential danger it poses. But researchers are constantly forced to play catch-up by following bird flu’s path through the avian population and trying to track its shifting genetics.
The way to finally get the jump on bird flu would be to create a weapon that works against the whole family of avian flu viruses, whatever their slight genetic quirks. And researchers led by Laurence Tiley say in Science this week that they might have found that kind of comprehensive trick: a genetic modification that seems to prevent flu from spreading in chickens.
It’s a decoy.
The birds carry a genetic tweak that diverts an enzyme crucial for transmitting the H5N1 strain. Although they die of the disease within days, the molecular decoy somehow impedes the virus from infecting others. [Nature]
Specifically, this genetic tweak allows the birds to create an RNA impostor. It matches up to the polymerase enzyme the flu virus would use to replicate its genetic material, so that enzyme is attracted to the decoy, which throws off viral replication. Though the modified chickens that were infected with avian flu died, the fact that they didn’t spread the virus is a potentially huge find—once avian flu enters a chicken population it typically spreads like wildfire.