Figure 6. In situ hybridization - pool A transcripts.

Pool A transcripts showing axially restricted expression patterns. (A) A4 (A. millepora C012-D9) is strongly expressed in the aboral two-thirds of the planula larva, with a band of minimal expression separating this expression from the strongly expressing oral end (1). Expression then becomes limited to the aboral end of the settling planula (2) and to the area of the future calicoblast layer (3–4). (B) A2 (EGF) Expression starts aborally in the pear stage (1) and remains strongest there throughout the planula and early settlement stages (2–4), becoming restricted to the future calicoblast layer at the time of settlement (5). (C) A52 (vWA domain protein). Expression is strongest in the aboral endoderm throughout the pre-settlement period (1–3) and continues in a restricted area at the aboral end post-settlement (4). (D) A101 (methyltransferase). In contrast to the other transcripts included in this figure, A101 is expressed orally throughout the stages investigated. Initially, in the early planula, it is expressed in a tight ring around the oral pore (1,2), while later expression forms a gradient running the full length of planula with the exception of the aboral end (3). Oral expression continues post-settlement (4). All pre-settlement stages are oriented with aboral to the right, as that end leads when swimming. Post-settlement stages A3 and C4 are shown looking directly onto the aboral surface, while A4 and B5 are oriented aboral side down.