They ground up heads, extracted the RNA from the tissue, sorted out the small RNA fragments, and sent those to a company that sequences DNA (or RNA, which is a similar molecule).
Because the entire honeybee genome has been sequenced, the short sequences the company supplied could be compared with the bee genome and non-matching sequences discarded as junk.
Various criteria were applied to the remaining sequences to whittle the candidates down to true miRNAs.
All of this sorting and sifting was done in collaboration with Weixiong Zhang, PhD, professor of computer science and engineering in the School of Engineering & Applied Science, who is an expert in computational biology.
"Zhang's lab has a lot of experience doing the bioinformatics part, which is important because not every little snippet of RNA is a miRNA; there are certain criteria they use to prove it's an miRNA," says Ben-Shahar.
At the end of this monumental cataloguing effort, the scientists had a list of 97 miRNAs that are expressed in the heads of honeybees, including 17 that had never been identified before, and many others that had been found in flies and mammals but not in bees.
Five prime suspects
To design a manageable behavioral experiment, the scientists then selected five of the 97 miRNAs for closer inspection. These five were either very abundant or had been implicated in neural function in other organisms.
The scientists then manipulated two colonies of bees to produce cohorts of nurse and forager bees that were the same age, either young for foragers or old for nurses.
They dissected out the brains of their precocious foragers and overage nurses and measured the level of expression o
|Contact: Diana Lutz|
Washington University in St. Louis