Figure 3

Modular spatial expression of mantle ESTs. Localized expression of 22 H. asinina ESTs in the juvenile mantle revealed by whole mount in situ hybridization (WMISH). (a) A representative de-shelled 5 mm (anterior-posterior) juvenile animal viewed dorsally. (b) Schematic representation of the animal shown in (a). The gills (g), digestive gland (dg), adductor muscle (am), epipodial tentacles (ept), right mantle lobe (rml), eyespot (es), cephalic tentacles (ct) and left mantle lobe (lml) are indicated. (c) The mantle tissue that covers the majority of the dorsal surface of the animal is shaded grey. The region illustrated in each uppercase panel below is indicated by the dashed box, and in each lowercase panel by the red box. (d) A schematic representation of the distal region of the mantle tissue where biomineralization takes place, corresponding to the red box in (c). The posterior zone of the outer fold (pzof), anterior zone of the outer fold (azof), periostracal groove (pg), inner fold (if), and anterior edge of the outer fold (aeof) are indicated. The first panel (uppercase) in each pair is a dorsal view of the anterior end of a juvenile, the second (lowercase) is a magnified view of the dissected mantle edge. Arrows in the first panel of each pair indicate the mantle and representative staining patterns. (E-G) Genes expressed discontinuously within the inner fold of the mantle. (H and h) Gene expressed discontinuously within both the inner mantle fold and the anterior crease of the outer fold. (I-M) Genes expressed continuously within both the inner fold and the anterior crease of the outer fold. (N and n) Gene expressed continuously within the anterior crease of the outer fold. (O-V) Genes expressed discontinuously within the anterior crease of outer fold. (W and w) HasSom expressed discontinuously within the anterior zone of the outer fold the mantle. (X-Z) Genes expressed ubiquitously within the posterior zone of the outer fold, corresponding with the area of nacre production. See Additional File 1 for details of ESTs used for in situ hybridization. Representative scale bar in (e) (for the second panel in each pair) is 200 μm. All animals possessed shells of between 5 and 6 mm (anterior-posterior).