Figure 2
CqSLC4A1 is localized in the apical membrane of the forming epithelia of the cuticular structures of the crayfish during mineralization. (a–c) A representative carapace cuticle from a post-molt animal. H&E. (a) × 4. Black box and lines indicate the area magnified in (b) × 10. Black box and lines indicate the area magnified in (c) × 40. (d–f) Carapace cuticle incubated with anti-CqSLC4A1 from animals at different molt stages: (d) inter-molt, (e) late pre-molt, and (f) post-molt. (g–i) Carapace cuticle of control animals at different molt stages: (g) inter-molt, (h) late pre-molt, and (i) post-molt. (j–l) A representative gastrolith from a late pre-molt animal. H&E. (j) × 4. Black box and lines indicate the area magnified in (k) × 10. Black box and lines indicate the area magnified in (l) × 40. (m–o) Gastrolith incubated with anti-CqSLC4A1 from animals at different molt stages: (m) inter-molt, (n) late pre-molt, and (o) post-molt. (p–q) Gastrolith of control animals at different molt stages: (p) inter-molt, (q) late pre-molt, and (r) post-molt. Arrows indicate significant staining of anti-CqSLC4A1. Cm cuticular matrix, Ce cuticular epithelium, Gm gastrolith matrix and Ge gastrolith epithelium. (s) Schematic representations of the post-molt cuticular mineralization: Left—the molecular mechanism of bicarbonate transport in the forming epithelia of the cuticle and the gastrolith in a crayfish. Middle—forming epithelial cells underneath the cuticular extracellular chitinous scaffold. Right—putative locations of the different transporters in the epithelial cells and the predicted bicarbonate transport mechanisms involving CqSLC4A1 and CqSLC4A7 and transport-assisting mechanisms involving CqSLC12A2 and Na+/K+-ATPase.
