Cellular proliferation assays are the workhorse of biological research. With regard to mammalian cells, proliferation is the crux of tissue and organ growth, while uncontrolled growth is the hallmark of cancer. Proliferation assays aid in elucidating those elements necessary for coordinated cell growth, as well as identifying agents that are potential anti-tumor agents. Likewise, the effect that compounds have on cellular proliferation is a key element of the ADME/Tox drug discovery process.
Proliferation assays are not confined to mammalian cells. Strains of the yeast Saccharomyces cerevisiea serve critical roles in the production of many different products including food staples, medicines, and biofuels. Optimization of these processes often involve the development of strains that are capable of growth under a wide variety of environmental conditions. Biofuel development from algae requires the careful monitoring of both cell number and intracellular lipid accumulation. Bacterial growth is monitored with regard to antibiotic resistance.
Microplate based proliferation assays can take on many different characteristics. Fluorescence stains that bind DNA are used to quantitate relative changes in DNA using whole-well PMT-based detection. Likewise, stained nuclei can be counted using microscopy followed by image-based analysis. Likewise, compounds that become colored, fluorescent or luminescent when acted upon live cells can be used to quantitate cell growth or cell death though increases or decreased of their signal respectively. Growth of single celled organisms in suspension culture can be monitored using turbidity or light scatter measurements. As the number of cells increases, the solution becomes increasingly cloudy or turbid because light passing through it is scattered by the microorganisms present.
BioTek developed several application notes describing a variety of cellular and microbial growth assays. See an example here
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