131. Mouse Genetics and Mutagenesis for Functional Genomics: The Chromosome 7 and 15 Mutagenesis Programs at the Oak Ridge National Laboratory 

E. M. Rinchik, D. A. Carpenter, E. J. Michaud, Y. You, P. R. Hunsicker, and D. K. Johnson 
Life Sciences Division, Oak Ridge National Laboratory, PO Box 2009, Oak Ridge, Tennessee 37831-8077 
rinchikem@ornl.gov 

The development of detailed mutation maps of regions of the mouse genome provides new resources for the study of mammalian biology and serves as an important functional complement to the human genome program. Mouse-human linkage homologies permit a type of "surrogate genetics" to be developed for regions of the human genome that is based on analyzing the molecular and organismal consequences of mutations mapping within the corresponding mouse genomic segment. One of the major goals of the mouse genetics program at ORNL is to apply our experience in chemical germ-cell mutagenesis and mutation recovery and propagation, as well as recently developed and evolving broad-based phenotype screening, for creating a large, user-friendly mouse-mutation resource for use by the functional-genomics and wider biological communities. 

For a number of years, we have been molecularly characterizing regions of mouse Chromosome (Chr) 7 while recovering, in parallel, N-ethyl-N-nitrosourea (ENU)-induced, recessive single-gene mutations mapping within those regions by two-generation hemizygosity screens with radiation-induced deletions. Mutagenesis of one 6- to 11-cM region surrounding the albino (c; Tyr) locus has been completed, yielding 31 mutations representing ten complementation groups. An on-going screen of another ~4- to 5-cM Chr-7 region, proximal to the pink-eyed dilution (p) locus (human 11p and 15q homologies), has so far yielded 19 new mutations, representing 8 complementation groups, from a screen of just 1218 gametes. Both of these screens have greatly increased the fine-structure genetic and functional maps of the corresponding regions. In addition to these hemizygosity screens, we shall also describe new work about to get underway that involves three-generation, homozygosity strategies to induce mutations in proximal Chr 7 (human 19q homology), mid Chr 7 (human 15q homology), and mid-to-distal Chr 15 (human 8q, 22q, and 12q homologies), which are large, multi-megabase regions that are currently not covered by complexes of deletions. We shall discuss our emphasis on up-front investment in developing genetic reagents so that any mutation created can be maintained and used by a wide variety of investigators with no molecular genotyping. In addition, we shall discuss the potential value of "parallel processing" in regional mutagenesis of the mouse genome, in which chromosomally "pre-mapped" mutations are recovered by three-generation screens with inversions in parallel to (not following) the development of deletions in embryonic stem cells for use as finer-mapping and gene-identification reagents. Mutant stocks generated in any of our screens will be advertised on the Web (http://lsd.ornl.gov/htmouse/ mmdmain.htm) and made available to the scientific community. 

[Research currently sponsored by the Office of Biological and Environmental Research, US DOE, under contract DE-AC05-960R22464 with Lockheed Martin Energy Research, Inc., and in the past by US DOE and the National Human Genome Research Institute (HG 00370).]