What worker bees do depends on how old they are. A worker a few days old will become a nurse bee that devotes herself to feeding larvae (brood), secreting beeswax to seal the cells that contain brood and attending to the queen.
Honeybees are eusocial insects, meaning that a colony behaves more like a superorganism than a gathering of individuals. Several genomes of several other eusocial insects had recently been sequenced. Do eusocial insects share miRNAs?
The grand survey of miRNAs had identified 20 miRNAs that seemed to be honeybee-specific. To test their idea, a group of scientists looked for these miRNAs in the genomes of four other eusocial insects within the hymenoptera (an order of insects that consists of ants, bees and wasps) and in that of a solitary wasp. A total of 19 out of the 20 miRNAs that had initially appeared to be honeybee-specific were also identified in the genomes of the other eusocial insects. Moreover, five found in all the eusocial hymenoptera were found in no other species. And none of the 20 miRNAS found in the eusocial insects were found in the genome of the solitary wasp.
Once a miRNA assumes a functional role it is rarely lost from an animal's genome, Yehuda Ben-Shahar, PhD, assistant professor of biology in Arts & Sciences at Washington University in St. Louis, says, because it typically regulates multiple genes and is too thoroughly enmeshed in the cell's regulation to be easily extracted. This makes miRNAs a valuable marker for evolutionary relationships among species.
The relationships among eusocial species could do with clarification. Ants and bees diverged a long time ago, and all ant species are eusocial, but bee species run the gamut from solitary to eusocial.
That pattern makes sense, Ben-Shahar says, only if the eusocial trait evolved more than once as new species evolved. Something in hymenoptera DNA may have made that group of animals more sensitive than others to whatever evolutionary pressures led to social behavior, he says.
Genetic control of human behavior is undoubtedly more complicated, Ben-Shahar says, but he points out that the human genome encodes close to 2,000 miRNAS, including two of the five he studied in bee brains, and these 2,000 miRNAs are thought to target roughly 60 percent of our genes.
Via Dr. Stefan Gruenwald