DETECTION OF GENES THAT ARE DIFFERENTIALLY EXPRESSED DURING MOUSE EMBRYOGENESIS BY GENETIC TRAPPING STRATEGIES

OBJECTIVE: Our objective was to identify novel genes that are expresse d in temporally and spatially restricted patterns during mouse embryon ic development and organogenesis. STUDY DESIGN: Two genetic trapping r eporter constructs that lack transcriptional regulatory sequences were introduced independently into transcriptionally active gene loci by e lectroporation into mouse embryonic stem cells. Patterns of host gene- reporter construct expression were investigated in differentiated embr yonic stem cells, embryoid bodies, and chimeric embryos at various sta ges of development. RESULTS: Three patterns of host gene-reporter cons truct expression were observed from the developmental analysis of four vector-integrated cell lines. Reporter expression patterns reflecting developmental regulation, constitutive activity, and developmental in activation of the host genes were observed. CONCLUSIONS: Two vector-in tegrated gene loci from cell lines CCE-1C1 and D3-B44 have expression patterns not previously described by genetic trapping. Molecular chara cterization of these interrupted genes will shed light on their develo pmental function.