Batmouse

A recent report in Genes and Development demonstrates how small variations in regulatory sequences can lead to large morphological variations. Researchers have generated mice with longer forelimbs by inserting into their genomes a piece of DNA that regulates wing development in the short-tailed fruit bat, Carollia perspicillata.

From the MS, "We replaced a limb-specific transcriptional enhancer of the mouse Prx1 locus with the orthologous sequence from a bat. Prx1 expression directed by the bat enhancer results in elevated transcript levels in developing forelimb bones and forelimbs that are significantly longer than controls."

In the photos, A & B are bat and mouse scaled for body length. C is the developmental stages of bat (top) and mouse (bottom) forelimbs. D is the same bat, but the mouse is now transgenic for the Prx1 regulatory region (scale similar to C).

The investigators conclude, "These findings suggest that mutations accumulating in pre-existing noncoding regulatory sequences within a population are a source of variation for the evolution of morphological differences between species and that cis-regulatory redundancy may facilitate accumulation of such mutations."

In other words, we are only a few steps away from winged mice.