Understanding how a compound or drug affects cellular pathways often requires measuring kinetic changes over an extended period of time—from several hours to days. Live-cell kinetic cell-based assays that measure cell viability, cytotoxicity, apoptosis and other cellular pathways are great for collecting real-time data. You don’t necessarily need expensive equipment to run these types of assays. In the videos below, Dr. Sarah Mahan, a research scientist at Promega, demonstrates how you can easily get great 24-hour or multi-day kinetic data using a GloMax® Microplate Reader.Continue reading “How to Get Real-Time Kinetic Data With GloMax® Microplate Readers”
It’s a question I’m asked probably once a week. “What wavelength do I select on my luminometer when performing a luciferase assay?” The question is a good and not altogether unexpected one, especially for those new to bioluminescent assays. The answer is that in most cases, you don’t and in fact shouldn’t select a wavelength (the exception to this rule is if you’re measuring light emitted in two simultaneous luciferase reactions). To understand why requires a bit of an explanation of absorbance, fluorescence, and luminescence assays, and the differences among them.
Absorbance, fluorescence, and luminescence assays are all means to quantify something of interest, be that a genetic reporter, cell viability, cytotoxicity, apoptosis, or other markers. In principle, they are all similar. For example, a genetic reporter assay is an indicator of gene expression. The promoter of a gene of interest can be cloned upstream of a reporter such as β-galactosidase, GFP, or firefly luciferase. The amount of each of these reporters that is transcribed into mRNA and translated into protein by the cell is indicative of the endogenous expression of the gene of interest.Continue reading “Why You Don’t Need to Select a Wavelength for a Luciferase Assay”