Fig. 6

Summary of gene expression during Ph. harmeri embryonic development. Schematic representation of the expression patterns of endomesodermal, anterior and posterior markers during embryonic development of Ph. harmeri. a The endodermal genes foxA and gata4/5/6 are expressed in the vegetal plate in blastula and later on are patterning the formation of the archenteron. FoxA is eventually confined in the foregut, whilst gata4/5/6 is expressed in the midgut. The mesodermal marker twist is labeling the anterior and posterior mesoderm and its derivatives. b The anterior gene six3/6 is expressed in the animal pole in blastula and at the gastrula stage is also activated in the anterior mesoderm and clusters of cells of the future midgut. At the early, pre-tentacle and six-tentacle larva stages six3/6 is restricted in the apical organ, anterior mesoderm and the oral ectoderm. Otx is expressed broadly at the blastula stage, and in gastrula it labels the anterior lip of the blastopore, adjacent to the expression of nk2.1 and gsc. At the gastrula stage, otx, nk2.1 and gsc are labeling the anterior–ventral ectoderm. Otx is also expressed in the future apical organ and the future midgut, and nk2.1 is additionally labeling the future hindgut. Later on, otx and nk2.1 are marking the ventral ectoderm of the pre-oral lobe. Otx together with gsc are demarcating the mouth. Additionally, otx labels the apical organ and nk2.1 is expressed strongly in the intestine and in the cardiac sphincter. c The posterior markers bra and cdx are expressed in the posterior lip of the blastopore at the gastrula stage. Bra is expressed in the ventral midgut, the ventral ectoderm and the posterior ciliary band, whilst cdx is confined in the intestine. At the six-tentacle larva stage, bra is activated in the intestine, the stomach diverticulum and the ventral ectoderm. The depicted expression patterns are for guidance and not necessarily represent exact expression domains. Drawings are not to scale. LV, lateral view; VV, vegetal view