Transgenic construct used in a study of the Fab-7 element. Contains two divergently transcribed reporters: a w+C marker and a lacZ reporter driven by a minimal eve promoter. A 200bp SpeI-BamHI enhancer fragment that directs expression of the h stripe 1 (H1) has been inserted between the two divergent promoters. A 1kb spacer (MAR region of the mouse μ light chain gene) and a 300bp StyI-XhoI DNA fragment containing the NEE rho enhancer have been inserted downstream of the lacZ reporter.