"The question that we started with was, are there microRNAs that are showing a response to song in the brain?" Clayton said. "And the answer is clearly yes, there are. The bigger question that we don't have an answer to yet is what are they doing?"
The study team, which included researchers from the Baylor College of Medicine and the University of Houston, also identified a microRNA that went up in males and down in females after the birds heard a new song. The gene for this microRNA is on the Z chromosome, the zebra finch's sex chromosome. Male zebra finches have two copies of the gene and females have only one, suggesting that even baseline levels of this microRNA differ between the sexes.
"To my knowledge, this is the first example of a gene response that's different in male and female songbirds," said Clayton, who also is an affiliate of the Institute of Genomic Biology and the Beckman Institute, both at Illinois.
Since microRNAs can interfere with the translation of mRNAs into protein, Clayton hypothesizes that mRNAs play a part in fine-tuning the brain's response to important signals.
"We do see a sudden disappearance of some types of messenger RNA shortly after a bird hears a song," he said. "We don't yet know the mechanism of that, but that's something a microRNA could be doing."
|Contact: Diana Yates|
University of Illinois at Urbana-Champaign