Edward J. Michaud, Irina Khrebtukova, Carmen M. Foster, and Tuan Vo-Dinh 
Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2009, Oak Ridge, TN 37831-8077 
michaudej@bio.ornl.gov 

Rapid progress has been made by the human genome sciences community in the last several years in generating nearly complete physical maps of several human chromosomes. In the very near future, the map positions and DNA sequence of the estimated 100,000 genes that make up a healthy individual will also be known. Sequence information alone, however, is often insufficient to ascertain the biological roles that genes play in normal human development and health. In order to determine the organismal function of every human gene and to understand how specific DNA mutations in genes result in birth defects and disease, strategies will need to be employed that are cost effective, scaleable to the entire genome, and that complement the mapping and sequencing data. 

One powerful approach for mapping the biological functions of many human genes that reside along large segments of chromosomes is to generate nested sets of chromosomal deletions in the homologous regions in mice. Deletion complexes at defined loci on mouse chromosomes permit fine-structure gene-function maps to be constructed, based on heritable mutations with specific phenotypes, that are then correlated with the available physical maps. Unfortunately, deletion complexes are currently available for only about 14% of the mouse genome. However, a new method was recently described (You et al., Nature Genet. 15:285-288, 1997; Thomas et al., Proc. Natl. Acad. Sci. USA 95:1114-1119, 1998) that permits deletion complexes to be generated anywhere in the mouse genome in F1 hybrid embryonic stem (ES) cells. The method is rapid and cost effective because the deletions are generated at defined locations in the genome and selected for in the ES cells. Additionally, many different deletions can be generated in one experiment and the extent of the deletion breakpoints can be mapped with available polymorphic markers before producing lines of mice. 

The objective of this project is to develop ES-cell reagents to facilitate the generation of functional maps in gene-rich regions that are homologous to portions of human chromosomes being mapped and sequenced by the Joint Genome Institute. The initial focus of this project will be to generate nested sets of chromosomal deletions in ES cells for the proximal 23 cM of mouse Chr 7 (human 19q homology) and a 16 cM region of proximal mouse Chr 11 (human 5q homology). ES-cell clones containing chromosomal deletions are the first reagents that will be generated and made available to the scientific community. As the project progresses, the goal will be to generate lines of mice harboring these chromosomal deletions and to archive these mutations in the form of cryopreserved embryos and spermatozoa. The reagents generated during this project will be advertised on the Joint Genome Institute Functional Genomics web site. 

This work is supported by the U.S. Department of Energy FWP ERKP293, in collaboration with the Joint Genome Institute.