When
did the enamel that covers our teeth evolve? And where in the body did
this tissue first appear? In a new study, researchers combined data from
two very different research fields - paleontology and genomics to
arrive at a clear but unexpected answer to this question: enamel
originated in the skin and colonized the teeth much later.
A
research group found that in most of the fossil bony fishes along with
few archaic living ones such as the gar (Lepisosteus) from North
America, the scales are made up with an enamel-like tissue called
“ganoine”. They found that it contains genes for two of our three enamel
matrix proteins: the first to be identified from a ray-finned bony
fish. Furthermore, these genes are expressed in the skin, strongly
suggesting that ganoine is a form of enamel. The hardest substance
produced by the body is this enamel and this is made mostly of the
mineral apatite (calcium phosphate) deposited on a substrate of three
unique enamel matrix proteins.
Ref:
Qingming Qu, Tatjana Haitina, Min Zhu, Per Erik Ahlberg. New genomic
and fossil data illuminate the origin of enamel. Nature, 2015.
DOI: 10.1038/nature15259
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