Expression constructs and summary of expression. (A) Expression constructs with different lengths of the sox9b promoter. The founders obtained for each segment are designated as lines A,B,C,D, or E. (B) Lateral images of 96 hpf zebrafish from each stable transgenic line, using confocal microscopy showing EGFP reporter expression as green fluorescence. Abbreviations: brain, b; heart, h; jaw, j; skeletal muscle, m; and notochord, n. The + indicates consistently observed; the indicates consistently not observed; +/ indicates sporadic or weak occurrence in offspring.

Transient expression analysis of different lengths 5′ of sox9b. Lateral images of 96 hpf zebrafish from transient experiments using the indicated promoter sequences. Newly fertilized eggs were injected as described in the Materials and methods, and images were recorded using confocal microscopy showing EGFP reporter expression as green fluorescence. Abbreviations: brain, b; heart, h; jaw, j; skeletal muscle, m; and notochord, n. The + indicates consistently observed; the - indicates consistently not observed; +/- indicates sporadic or weak occurrence in offspring.

Expression of interspecies conserved non-coding elements. (A) Minimal sox9b promoter construct (sox9b CPE) driving EGFP expression. (B) sox9b core promoter with the additional fish CNEs (sox9b CPE + fish CNEs) driving EGFP expression. (C) Lateral views in the green channel of 96 hpf zebrafish transiently expressing EGFP under control of the various sox9b:EGFP constructs. Abbreviations are: brain, b; heart, h; jaw, j; skeletal muscle, m; and notochord, n.

Example of mosaic expression of transgenes in the jaw. Example of mosaic expression of the full length  2421/+29 sequence after injection as described in the Methods. Shown is a ventral confocal view of mosaic EGFP expression 31 in the Meckel′s cartilage (jaw) at 96 hpf. The Meckel′s (Me, chondrocytes), ceratohyal, (ch, perichondrium), and palatoquadrate (pq, chondrocytes) cartilages have arrows for orientation.