Temple called to point me to two new articles in Science News
, one on the 'danger mouse,' and one on bees.
Here's the mouse:
By removing one gene from a mouse's standard repertoire, scientists have turned a timid animal into an intrepid one.
Gleb Shumyatsky of Rutgers University in Piscataway, N.J., and his colleagues study the genetics that affect how animals remember scary stimuli and how they respond to fright. "Fear is definitely important when you think about the survival of an organism," Shumyatsky says. "If you make a single mistake, you can be eaten or killed."
In 2002, Shumyatsky and his team discovered that the amygdala, which processes fear, has high levels of a protein called stathmin
So they bred a knock-out mouse lacking the gene that directs the production of stathmin.
Then they looked at two kinds of fear:
- innate fear (heights, predators)
- learned fear (such as a tone that signals a shock)
The stathmin-free mice were far less fearful:
When normal mice are released into a new cage, they skulk near the edges. A hardwired fear of possible predators seems to keep the animals from immediately exploring their environment. Shumyatsky and his colleagues found that mice missing stathmin strolled into the middle of new cages sooner than normal mice did. In another experiment, stathmin-free mice spent more time than normal mice did on platforms set up 50 centimeters above the floor.
Standing up high on a platform is something dogs and cats do, not mice.
The knock-out mice were less troubled by learned fears, too:
Shumyatsky and his team taught groups of mice to expect a mild shock after hearing a loud tone. Normal mice froze in place for several seconds whenever they heard the tone, even if the shock didn't come. Although stathminfree mice also struck a pose at the sound of the tone, they held it only 60 percent as long as the normal mice did.
Nothing else seems
to have been affected. The knockout mice looked normal in memory, hearing, and pain perception—and they did have some
fear: "They weren't stupid," Shumyatsky told SCIENCE NEWS. "If you wanted to catch them, they ran away."
However, other areas of the brain produce stathmin as well, so it's reasonable to assume that it's involved in other behaviors, too, as Joseph LeDoux of NYU points out.
I'll be interested to see what other behaviors stathmin might affect.source:
Danger Mouse: Deleting a gene transforms timid rodents into daredevilsWeek of Nov. 26, 2005; Vol. 168, No. 22 , p. 341