Robert Singer and colleagues at the Albert Einstein College of Medicine in New York recently visualized individual Dictyostelium discoideum cells transcribing dscA, a gene that increases in expression during development. Using an in vivo system that tags nacent mRNA, they showed dscA is transcribed in pulses.
"People carry around a picture about these things. Most people would expect that once a gene is on, it?s on. And if it?s off, it?s off. It wouldn?t be flipping between the two all the time. But that?s what they found. They speculate that...