The 350 bp core region of the +45 element insulates transgenic constructs and improves tissue-specific expression from the Scl promoter.

<p>The total number of F0 transgenic embryos obtained with each construct was determined by PCR using specific primers. Upon ß-galactosidase staining, transgenic embryos were visually inspected and scored as either LacZ+ or LacZ- and the percentage of LacZ+ embryos calculated.</p>*<p>p<0.05 compared to SV/LacZ. The expression pattern of Scl/LacZ and 350/Scl/LacZ/350 transgenic embryos is considered ectopic if beyond the mid and hind brain, the expected expression pattern for the Scl promoter alone.</p>**<p>p<0.01 compared to Scl/LacZ.