Methods for quantifying radioisotopes on membranes, gels, and microtiter trays are fundamental to molecular biology and related research areas. Until recently, these methods were difficult, tedious, and time-consuming, requiring the scientist to expose the plates to X- ray film for periods ranging from a few hours to a week or more.

But a new method for identifying and classifying bacteria by imaging the radioisotope distribution has been developed by the Department of Reproductive Physiology at St. Bartholomew’s Hospital Medical College in London.

A team headed by Robert Silman was investigating the translation of mRNA labeled with 35S while researching the ACTH peptide hormones of the pituitary gland. They were identifying the translation products by polyacrylamide gel electrophoresis and autoradiography, when on one occasion they unknowingly laced their samples with bacteria. Many unexpected bands, resembling the bar codes on supermarket merchandise, appeared in the autoradiograph.

With help from the Department of...

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