The challenge of the postgenomic era is not only to assign functions to individual genes, but also to determine how sets of genes act in concert to control biological processes. This formidable task is even more daunting when one attempts to understand the complex genetic programs underlying nervous system development. More than half of the approximately 25,000 genes in the mouse genome are thought to be involved in development and function of the nervous system [ 1, 2], but only 30% of genes have any function assigned to them [ 3]. Identifying the temporal and spatial expression patterns of these genes throughout development is a critical initial step that lays the groundwork for additional functional analyses. Toward this goal, we have developed a publicly available database of gene expression patterns, the St. Jude Brain Gene Expression Map (BGEM).
BGEM ( http://www.stjudebgem.org) is a growing collection of in situ hybridization images of gene expression patterns in the nervous system of the developing and adult C57BL/6 mouse. Data are displayed on an image-centric Web site in a format that enables easy visualization of temporal and spatial changes in gene expression. Currently, the information in BGEM is used to select candidate genes for use in constructing BAC transgenic mice as part of the Gene Expression Nervous System Atlas (GENSAT) project ( http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=gensat and http://www.gensat.org). The GENSAT project is designed to document the expression patterns of all genes in the nervous system and to generate transgenic mice expressing reporter constructs that recapitulate the authentic expression patterns of selected genes. GENSAT is supported by the National Institutes of Neurological Disorders and Stroke and by the National Institutes of Health Neurosciences Blueprint ( http://neuroscienceblueprint.nih.gov), a partnership of 14 NIH institutes and centers committed to accelerating understanding of the nervous system.