DNA sequencing. Computer image of a coloured auto- radiogram showing sequenced cDNA (complementary DNA), from a 32-lane electrophoresis gel. Colour bands correspond to base pairs that form the code for a section of cDNA. This is research conducted at The Institute for Genomic Research (TIGR) in Gaithersburg, Maryland, USA. Here scientists analyse the structure and function of human genes, and animal & plant genes for comparison. At TIGR, cDNA ESTs (Expressed Sequence Tags) are produced; these tags" enable the reading of cDNA, lengths of copied genetic material identical to genes. Mapping human genes will enable the development of genetic therapies for inherited human diseases."