When a gene is expressed or “turned on,” genetic information is transferred from DNA into RNA. This process, known as transcription, is crucial for translating the gene’s message into a functional protein. Diseases such as cancer can result when genes turn on at the improper time or in the wrong part of the body.
Researchers customarily use microarrays (also known as “gene chips”) to assess gene expression in tumors and other tissues. But with millions of cells involved, microarrays reflect only “average” gene expression. Just how a gene is transcribed in a single cell—continuously, intermittently or some other way—has largely been a mystery.
Now, in observing a gene that plays a major role in how an organism develops, the Einstein researchers observed a phenomenon that until now has been indirectly observed and only in bacteria: pulses of transcription that turn on and off at irregular intervals. Dr. Singer and his co-workers used a fluorescent marker that sticks to the gene only when it is active. Under a microscope, this fluorescent marker appears when the gene turns on, then disappears (gene “off”) and then appears again (gene “on”).