Testing the role of a conserved element in gene regulation

A transcriptional cis-acting regulatory element is identified in an ultraconserved element of the human genome. An ultraconserved element lying near the human ISL1 gene was coupled to a reporter gene and injected into fertilized mouse oocytes. The regions where the gene is expressed are stained dark blue or black. (a) The reporter gene is expressed in the head and spinal cord of a transgenic mouse, as seen here on day 11.5 of gestation. This expression pattern corresponds to (b) the native pattern of expression of the mouse ISL1 gene on day 11.5 of gestation. This experiment demonstrates how functional noncoding elements can be identified by comparative genomics and tested in a model organism.

[From G. Bejerono et al., “A Distal Enhancer and an Ultraconserved Exon Are Derived from a Novel Retroposon,” Nature 441, 2006, 87–90, Fig. 3.]