Fig.2.

Illustrations of in vivo expression of recombineered marker BACs carrying GFP coding sequences inserted immediately following ATG in the genes included in this study. BACs were injected into fertilized eggs at about 500 copies, and in each case the cells expressing them are skeletogenic. At mesenchyme blastula stage these cells form bilateral clusters on the floor of the blastocoel; as gastrulation proceeds they form characteristic rings surrounding the archenteron; later form syncytial chains as they secrete skeletal rods within which GFP diffuses from cell to cell. Gene names are shown on figure panels. Genomic maps of BACs and gene regions can be accessed by reference to BAC designations as listed in Table 1 in Echinobase (http://www.echinobase.org/Echinobase/).