The African bichir (Polypterus senegalus) is a living representative of Polypteriformes. P. senegalus possesses teeth composed of dentin covered by an enameloid cap and a layer of collar enamel on the tooth shaft, as in lepisosteids. A thin layer of enamel matrix can also be found covering the cap enameloid after its maturation and during the collar enamel formation. Teleosts fish do not possess enamel; teeth are protected by cap and collar enameloid, and inversely in sarcopterygians, where teeth are only covered by enamel, with the exception of the cap enameloid in teeth of larval urodeles. The presence of enameloid and enamel in the teeth of the same organism is an opportunity to solve the evolutionary history of the presence of enamel/enameloid in basal actinopterygians. In silico analyses of the jaw transcriptome of a juvenile bichir provided twenty SCPP transcripts. They included enamel, dentin, and bone-specific SCPPs known in sarcopterygians and several actinopterygian-specific SCPPs. The expression of these 20 genes was investigated by in situ hybridizations on jaw sections during tooth and dentary bone formation. A spatiotemporal expression patterns were established and compared with previous studies of SCPP gene expression during enamel/enameloid and bone formation. Similarities and differences were highlighted, and several SCPP transcripts were found specifically expressed during tooth or bone formation suggesting either conserved or new functions of these SCPPs.

非洲bichir（Polypterus senegalus）是Polypteriformes的活生生代表。塞内加尔对虾拥有由牙本质组成的牙齿，牙齿上覆盖有釉质帽和牙轴上的一层颈釉质，如鳞齿类动物。在帽釉质成熟后和颈圈釉质形成过程中，还可以发现一层薄薄的釉质基质覆盖在帽釉质上。硬骨鱼没有牙釉质；牙齿受到帽釉质和项圈釉质的保护，而肉翅目动物则相反，其牙齿仅被牙釉质覆盖，但有尾目幼虫牙齿中的帽釉质除外。同一生物体的牙齿中存在牙釉质和牙釉质，这为解决基底放线鱼中牙釉质/牙釉质存在的进化历史提供了机会。对幼年 bichir 下颌转录组的计算机分析提供了 20 个 SCPP 转录本。它们包括牙釉质、牙本质、以及肉翅目中已知的骨特异性 SCPP 和几种放线翅目特异性 SCPP。在牙齿和牙骨形成过程中，通过颌骨切片的原位杂交研究了这 20 个基因的表达。建立了时空表达模式，并与牙釉质/牙釉质和骨形成过程中 SCPP 基因表达的先前研究进行比较。突出了相似性和差异，并且发现了一些 SCPP 转录本在牙齿或骨骼形成过程中特异表达，表明这些 SCPP 具有保守功能或新功能。建立了时空表达模式，并与牙釉质/牙釉质和骨形成过程中 SCPP 基因表达的先前研究进行比较。突出了相似性和差异，并且发现了一些 SCPP 转录本在牙齿或骨骼形成过程中特异表达，表明这些 SCPP 具有保守功能或新功能。建立了时空表达模式，并与牙釉质/牙釉质和骨形成过程中 SCPP 基因表达的先前研究进行比较。突出了相似性和差异，并且发现了一些 SCPP 转录本在牙齿或骨骼形成过程中特异表达，表明这些 SCPP 具有保守功能或新功能。