Center for Gene Expression Profiling (CGEP)

Changes in gene expression are responsible for many biological phenomena. In the science of molecular biology the expression of individual genes can by analyzed by using hybridization of individual gene probes to samples of RNA spotted onto filter paper. This technology has provided many insights into tissue-specific expression of genes and the changes of gene expression caused by external stimuli. Nevertheless, only a small number of genes can be analyzed at any one time.

The development and sequencing of large collections of cDNAs (copy DNA) from many organisms in the past four years has opened up the possibility of analyzing the expression of thousands of genes simultaneously by using cDNA microarray technology. First a fluorescent probe is produced from mRNA (messenger RNA) isolated from an organism that responds to a specific external stimulus (e.g., pathogen attack) or from an organ at a specific developmental stage (e.g., ripening fruit). The probe is then hybridized to many thousands of cDNA inserts that have been individually affixed to a solid surface, usually a glass slide (a “microarray”). Genes that are expressed in the tissue being studied hybridize to the corresponding cDNA, and the fluorescence is detected by a confocal laser scanner. The resulting image is analyzed using software specially developed for the purpose. Through this experimental approach new genes that are involved in specific biological processes can be quickly identified. It is already being used in mammalian genomics and will have important ramifications in the study of plants and microbes.

To take advantage of the broad usefulness of cDNA microarray technology, the BTI has recently established a Center for Gene Expression Profiling. Services provided by the facility are available to researchers in the Cornell community, including those at the BTI, Cornell University, and the USDA Plant, Soil, and Nutrition Laboratory. The center is equipped to analyze genome-wide gene expression changes in a variety of organisms, including plants, mammals, insects, and microbes. Available equipment includes two robotic microarrayers to develop high-density arrays of cDNAs on nylon membranes or glass slides, a confocal laser scanner for capturing hybridization images, and computer and software support for analyzing large data files. Start-up funds for equipment and operation of the center were provided by the BTI and an NSF Major Research Infrastructure equipment grant. A user fee system will be implemented to provide continuing financial support.