Model Organism Research
Most mapping and sequencing technologies were developed from studies of nonhuman genomes, notably those of the bacterium Escherichia coli, the yeast Saccharomyces cerevisiae, the fruit fly Drosophila melanogaster, the roundworm Caenorhabditis elegans, and the laboratory mouse Mus musculus. These simpler systems provide excellent models for developing and testing the procedures needed for studying the much more complex human genome.
A large amount of genetic information has already been derived from these organisms, providing valuable data for the analysis of normal gene regulation, genetic diseases, and evolutionary processes. Physical maps have been completed for E. coli, and extensive overlapping clone sets are available for S. cerevisiae and C. elegans. In addition, sequencing projects have been initiated by the NIH genome program for E. coli, S. cerevisiae, and C. elegans.
Mouse genome research will provide much significant comparative information because of the many biological and genetic similarities between mouse and man. Comparisons of human and mouse DNA sequences will reveal areas that have been conserved during evolution and are therefore important. An extensive database of mouse DNA sequences will allow counterparts of particular human genes to be identified in the mouse and extensively studied. Conversely, information on genes first found to be important in the mouse will lead to associated human studies. The mouse genetic map, based on morphological markers, has already led to many insights into human biology. Mouse models are being developed to explore the effects of mutations causing human diseases, including diabetes, muscular dystrophy, and several cancers. A genetic map based on DNA markers is presently being constructed, and a physical map is planned to allow direct comparison with the human physical map.