Copy-dependent and position-independent expression of rat aldolase A gene

In order to understand the molecular mechanisms of the temporal and spatial differences of gene expression in higher organisms, rat aldolase A gene carrying two distinct promoters was introduced into fertilized eggs and the resulting transgenic mice were analyzed. The transgene expression is tissue-specific and is developmentally regulated. In addition, the expression is regulated in a copy-dependent manner irrespective of where the transgene is integrated, suggesting that a mechanism excluding the effect of the integration site exists within the transgene itself. To explore the conformational change of this gene in the genome, the DNase I hypersensitive sites of the gene were examined. Three sites (DHS-1,2, and 3) were identified upstream and downstream of the gene and these sites were retained in the transgene as well as in the gene observed endogenously.