New genomic and fossil data illuminate the origin of enamel

@article{Qu2015NewGA,
  title={New genomic and fossil data illuminate the origin of enamel},
  author={Qingming Qu and Tatjana Haitina and Min Zhu and Per Erik Ahlberg},
  journal={Nature},
  year={2015},
  volume={526},
  pages={108-111}
}
Enamel, the hardest vertebrate tissue, covers the teeth of almost all sarcopterygians (lobe-finned bony fishes and tetrapods) as well as the scales and dermal bones of many fossil lobe-fins. Enamel deposition requires an organic matrix containing the unique enamel matrix proteins (EMPs) amelogenin (AMEL), enamelin (ENAM) and ameloblastin (AMBN). Chondrichthyans (cartilaginous fishes) lack both enamel and EMP genes. Many fossil and a few living non-teleost actinopterygians (ray-finned bony… 

Immunolocalization of Enamel Matrix Protein-Like Proteins in the Tooth Enameloid of Actinopterygian Bony Fish

Transmission electron microscopy-based immunohistochemical examinations were performed in order to search for EMP-like proteins in the cap enameloid of basic actinopterygians, Polypterus and gar, detecting positive immunoreactivity just before the appearance of many crystallites along collagen fibrils, indicating that the cap Enameloid contains EMP- like proteins.

Skeletal Mineralization in Association with Type X Collagen Expression Is an Ancestral Feature for Jawed Vertebrates

These findings push the origin of Col10a1 gene prior to the divergence of osteichthyans and chondrichthyans, and demonstrate its ancestral association with mineralization of both the odontode skeleton and the endoskeleton.

Parallel Evolution of Ameloblastic scpp Genes in Bony and Cartilaginous Vertebrates

A single origin for the hypermineralized outer odontode layer as produced by an ancestral developmental process performed by Sparc-L is supported, implying the homology of the enamel and enameloid tissues in all vertebrates.

Ganoin and acrodin formation on scales and teeth in spotted gar: A vital role of enamelin in the unique process of enamel mineralization.

Investigation of the formation and mineralization of the ganoin and acrodin matrices in spotted gar and the evolution of the scpp5, ameloblastin (ambn), and enamelin (enam) genes suggest that, in bichirs and gars, all these genes retain structural characteristics of their orthologs in stem actinopterygians, presumably reflecting the presence of gano in on scales and teeth.

SCPP Genes and Their Relatives in Gar: Rapid Expansion of Mineralization Genes in Osteichthyans.

It appears that many SCPP genes expanded rapidly in stem osteichthyans and in basal actinopterygians, including many newly identified P/Q-rich genes expressed in teeth and/or scales.

Tooth development in the Early Devonian sarcopterygian Powichthys and the evolution of the crown osteichthyan dentition

In osteichthyans (bony fishes) the dentition is characterized by marginal tooth rows replaced by basal resorption. Basal resorption was present in the stem osteichthyan Andreolepis, which also

A Silurian maxillate placoderm illuminates jaw evolution

A second Silurian maxillate placoderm is described that more securely bridges the jawless toothlike plates of placoderms to the development of the jawed condition that ultimately led to the three-boned jaw in ancestors of modern vertebrates.

The developmental relationship between teeth and dermal odontodes in the most primitive bony fish Lophosteus

The ontogenetic trajectory of a marginal jawbone of Lophosteus superbus, the phylogenetically most basal stem osteichthyan, visualized by synchrotron microtomography, reveals a developmental relationship between teeth and dermal odontodes that is not evident from the adult morphology.
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References

SHOWING 1-10 OF 34 REFERENCES

The SCPP Gene Family and the Complexity of Hard Tissues in Vertebrates

It appears that, in vertebrates, the phenotypic complexity of hard tissues correlates with gain and loss of SCPP genes, and distinct roles of acidic and P/Q-rich SCPPs during the evolution ofhard tissues are suggested.

The SCPP gene repertoire in bony vertebrates and graded differences in mineralized tissues

The repertoire of SCPP genes in the zebrafish, frog, and humans includes many lineage-specific genes and some widely conserved genes that originated in stem osteichthyans or earlier, reinforcing the hypothesis that bone–dentin–enameloid–enameless constitutes an evolutionary continuum.

Phenogenetic drift in evolution: the changing genetic basis of vertebrate teeth.

It is shown that teleost fish also use manySCPPs for enameloid and dentin mineralization, but none of these directly corresponds to tetrapod SCPPs, which suggests thatteleost and tetrapods SCPP genes have experienced independent parallel duplication histories.

Scales and Tooth Whorls of Ancient Fishes Challenge Distinction between External and Oral ‘Teeth’

The new findings reveal, for the first time, how polyodontode scales grow in 3D in an extinct bony fish and show that dentition-like odontode patterning occurs on scales and that the primary patterning unit of a tooth whorl may be the bony base rather than the odontodes it carries.

The Origin and Evolution of Enamel Mineralization Genes

The evolutionary analysis of AMEL led to propose a dataset that will be useful to validate AMEL mutations leading to X- linked AI, and numerous residues were unchanged during >200 million years, suggesting that they are important for the proper function of the protein.

True enamel covering in teeth of the Australian lungfish Neoceratodus forsteri

The enamel layer of lungfish teeth is investigated to determine whether there was evidence for higher vertebrate "true" enamel in the Australian lungfish and it is confirmed that true enamel is found not only in tetrapods but also in the sarcopterygian clade of the Gnathostomata.

Testing models of dental development in the earliest bony vertebrates, Andreolepis and Lophosteus

These fossil remains have no bearing on the nature of the dentition in osteichthyans and, indeed, the results raise questions concerning the homologies of these bones and the phylogenetic classification of Andreolepis and Lophosteus.

SCPP genes in the coelacanth: tissue mineralization genes shared by sarcopterygians.

  • K. KawasakiC. Amemiya
  • Biology
    Journal of experimental zoology. Part B, Molecular and developmental evolution
  • 2014
The three Pro/Gln-rich SCPP genes, required for mineralizing enamel matrix and confirmed only in tetrapods, were all identified in the coelacanth, strongly suggesting that enamel is equivalent in theCoelacant and tetrapod, corroborates the previous proposition that true enamel evolved much earlier than the origin of tetrapoda.

Jaws and teeth of the earliest bony fishes

Andreolepis and Lophosteus are not only the oldest but also the most phylogenetically basal securely identified osteichthyans known so far, indicating that they can be assigned to the stem group.