Abstract
The availability of reference genome sequences for virtually all species under active research has revolutionized biology. Analyses of genomic variations in many organisms have provided insights into phenotypic traits, evolution and disease, and are transforming medicine. All genomic data from publicly funded projects are freely available in Internet-based databases, for download or searching via genome browsers such as Ensembl, Vega, NCBI's Map Viewer, and the UCSC Genome Browser. These online tools generate interactive graphical outputs of relevant chromosomal regions, showing genes, transcripts, and other genomic landmarks, and epigenetic features mapped by projects such as ENCODE.This chapter provides a broad overview of the major genomic databases and browsers, and describes various approaches and the latest resources for searching them. Methods are provided for identifying genomic locus and sequence information using gene names or codes, identifiers for DNA and RNA molecules and proteins; also from karyotype bands, chromosomal coordinates, sequences, motifs, and matrix-based patterns. Approaches are also described for batch retrieval of genomic information, performing more complex queries, and analyzing larger sets of experimental data, for example from next-generation sequencing projects.