Developmental biology and databases: how to archive, find and query gene expression patterns using the world wide web.

Systems biology has undergone an explosive growth in recent times. The staggering amount of expression data that can now be obtained from microarray chip analysis and high-throughput in situ screens has lent itself to the creation of large, terabyte-capacity databases in which to house gene expression patterns. Furthermore, innovative methods can be used to interrogate these databases and to link genomic information to functional information of embryonic cells, tissues and organs. These formidable advancements have led to the development of a whole host of online resources that have allowed biologists to probe the mysteries of growth and form with renewed zeal. This review seeks to highlight general features of these databases, and to identify the methods by which expression data can be retrieved.