Tissue-specific and developmental regulation of rod opsin chimeric genes in transgenic mice

Abstract Chimeric gene fusions between 4.4 kb of rod opsin 5′ flanking sequence fused to a diphtheria toxin gene and 4.4 kb or 500 by of rod opsin 5′ flanking sequence fused to the E. coli IacZ gene were used to generate transgenic mice for analysis of cell type-specific expression and temporal and spatial distribution of reporter gene product during retinal development. Opsin-diphtheria toxin transgene expression evoked photoreceptor-specific cell death. The 4.4 kb opsin- IacZ followed temporal and spatial gradients of expression that approximate opsin expression. The 500 by opsin fragment targeted expression to photoreceptors, but expression was weaker and nonuniform, suggesting that elements located upstream may be required for enhanced and uniform spatial expression.