| The mouse is one of the best models for biomedical studies. We describe in this dissertation our efforts for manipulating the mouse genome for cell lineage analysis and for high-throughput genomic analysis. First, we describe a practical Cre/loxP-based mutagenesis strategy to systematically mutate coding sequences and/or the vast noncoding regions of the mouse genome for large-scale functional genomic analysis of the mouse. To illustrate this approach, we have used gene targeting to create loxP-containing loss-of-function alleles in the protocadherin gene clusters (Pcdhalpha, beta and gamma). Using these alleles, we found that under proper guidance, Cre/loxP site-specific recombination could mediate efficient trans-allelic recombination in vivo, allowing generation of large germline deletions and duplications, including Pcdhalpha and Pcdhalpha through beta deletions, simply by breeding. Furthermore, the same breeding method was also able to generate germline translocations between nonhomologous chromosomes at reasonable frequencies. By incorporating a piggyBac transposon to randomly insert loxP sites throughout the mouse genome, we describe a simple and comprehensive method for the generation of genomewide insertions, deletions, and duplications. Second, we describe the creation of an efficient conditional cell ablation mouse line. When this mouse line is crossed to the Olig1-Cre mouse, differentiated motoneurons and oligodendrocytes are eliminated. Interestingly, a normal number of oligodendrocyte precursors are formed at day 12 of mouse development, after all motoneuron precursors have been killed. This result suggests that motoneurons and oligodendrocytes do not share common progenitors. |
