By collecting and analyzing thousands of points of light within a single cell, researchers at the Albert Einstein College of Medicine and their colleagues have for the first time visualized individual transcripts of messenger RNA.Their technique also permits the accurate quantitation of multiple RNA molecules, such as those that are found at transcription sites, the places on chromosomes where the genetic information is read out. The innovation, which relies on advanced imaging techniques, sophisticated algorithms, and the power of parallel computing, is described in the April 24, l998 cover story of Science. The lead author of the paper is Andrea Femino. The corresponding author is Robert H. Singer, head of the laboratory in which the research was conducted.
The new methodology holds promise for disclosing the operations of the cell at a heretofore unthought-of level of detail. For instance, using the technique scientists can study how many molecules of mRNA are transcribed from a particular gene during a particular unit of time. (Messenger RNA is the molecular intermediary from which information encoded in genes is translated into proteins.)
The Einstein researchers have already quantitated the kinetics of mRNA transcription from the beta-actin gene, and have found that the transcription is cyclical despite the constant presence of a stimulating signal."To our amazement, we found that transcription hits its peak in 30 minutes. By 60 minutes transcription falls off, and two hours later, it's gone." This indicates the existence of an as-yet- unknown regulatory feedback mechanism, says Singer.
The new technique has also enabled the researchers to show that the rate at
which genes are transcribed is limited not by the speed at which the copying
enzymes (polymerases) move down the gene with their growing mRNA transcript
attached, but rather by the number of polyme
Contact: Andrea Femino/Dr. Robert Singer
Albert Einstein College of Medicine