An enhancer is a sequence of DNA with the power to activate a specific gene. Since Darwin’s theory of natural selection, it is widely accepted that gene sequences are inherited and may be modified, providing a mechanism for change between generations. However, scientists have recently discovered that enhancers can be created completely from scratch (de novo). This completely new mechanism for creating variation between individuals highlights a new mechanism by which species evolve by natural selection. Using a technique known as a reporter assay, the team fused a GFP (green fluorescent protein) gene to one of four newly discovered enhancers, which were injected into fish embryos. They applied a powerful optical imaging technique called confocal microscopy, which highlights enhancer activity in the embryos by means of a green ‘glow’. This pinpoints where each enhancer is driving gene activation.
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