Assay for Phage Containing the Beta-galactosidase Gene Protocol This assay is used when working with phage vectors carrying the beta-galactosidase gene (often used for immunological screening). If the cloning event disrupts a normally functional copy of the gene in the vector the resulting plaques would appear clear in the assay. If the phages contain a functional beta-galactosidase gene they will form blue rings around their plaques. Any strain which is not an overproducer of beta- galactosidase will work as indicator host bacteria.
Assay of ß-Galactosidase in Yeast: Assay of Crude Extracts Protocol Protocol describes how a crude extract is prepared, and the activity is normalized to the amount of protein assayed. This method is particularly suitable for comparing cells that are grown under very different conditions or that have different genetic backgrounds.
