Phenotype microarray
The phenotype microarray approach is a technology for high-throughput phenotyping of cells.
A phenotype microarray system enables one to monitor simultaneously the phenotypic reaction of cells to environmental challenges or exogenous compounds in a high-throughput manner.
The phenotypic reactions are recorded as either end-point measurements or respiration kinetics similar to growth curves.
Usages
High-throughput phenotypic testing is increasingly important for exploring the biology of bacteria, fungi, yeasts, and animal cell lines such as human cancer cells. Just as DNA microarrays and proteomic technologies have made it possible to assay the expression level of thousands of genes or proteins all a once, phenotype microarrays make it possible to quantitatively measure thousands of cellular phenotypes simultaneously. The approach also offers potential for testing gene function and improving genome annotation. In contrast to many of the hitherto available molecular high-throughput technologies, phenotypic testing is processed with living cells, thus providing comprehensive information about the performance of entire cells. The major applications of the PM technology are in the fields of systems biology, microbial cell physiology, microbiology, and taxonomy, and mammalian cell physiology including clinical research such as on autism. Advantages of PMs over standard growth curves are that cellular respiration can be measured in environmental conditions where cellular replication may not be possible, and that it is more accurate than optical density, which can vary between different cellular morphologies. In addition, respiration reactions are usually detected much earlier than cellular growth.Technology
A sole carbon source that can be transported into a cell and metabolized to produce NADH engenders a redox potential and flow of electrons to reduce a tetrazolium dye, such as tetrazolium violet, which produces a purple color. The more rapid this metabolic flow, the more quickly purple color forms. The formation of purple color is a positive reaction. interpreted such that the sole carbon source is used as an energy source. A microplate reader and incubation facility are needed to provide the appropriate incubation conditions, and to automatically read the intensity of colour formation during tetrazolium reduction in intervals of, e.g., 15 minutes.The principal idea of retrieving information about the abilities of an organism and its special modes of action when making use of certain energy sources can be equivalently applied to other macro-nutrients such as nitrogen, sulfur, or phosphorus and their compounds and derivatives.
As an extension, the impact of auxotrophic supplements or antibiotics, heavy metals or other inhibitory compounds on the respiration behaviour of the cells can be determined.