Task allocation in honeybees is highly scripted, and yet the script is flexible enough to respond to labor shortages. If there aren't enough nurse bees in the colony, nurses will stick with their tasks past the usual age limit, becoming what are called overage nurses. And if there aren't enough foragers, bees too young for that role will rush to take it on, becoming precocious foragers.
For the scientists this plasticity makes bees a very powerful behavioral model. By comparing overage nurses to precocious foragers it is possible to compare gene expression in different behavioral states without the confounding factor of age.
A tiny off-switch
Ben-Shahar was curious about the role newly discovered molecules called miRNAs might play in the control of behavior.
Francis Crick, the co-discoverer of the structure of DNA, said in 1956 that the central dogma of biology is that DNA makes RNA makes protein and protein then does the cell's work, including activating other genes.
The central dogma still holds, but in the past 50 years it has been enormously complicated by the discovery of many mechanisms for regulating gene expression, including a proliferation of regulatory RNAs.
Among these are miRNAS, tiny snippets of noncoding RNA typically only 22 nucleotide units long that bind to RNA transcripts of a gene, reducing protein production and, in effect, silencing the gene.
Micro-RNAs are known to regulate development and disease processes such as cancer, Ben-Shahar says.
"We wondered if they weren't playing a role in regulating social behaviors," he says, "because recent studies have implicated them in complex nervous-system functions such as neurodevelopment, psychiatric disease, and circadian clocks."
A library of possibilities
Because nobody knew much about the mi
|Contact: Diana Lutz|
Washington University in St. Louis