title: Retinoic acid expands the evolutionarily reduced dentition of zebrafish.
abstract: Zebrafish lost anterior teeth during evolution but retain a posterior pharyngeal dentition that requires retinoic acid (RA) cell-cell signaling for its development. The purposes of this study were to test the sufficiency of RA to induce tooth development and to assess its role in evolution. We found that exposure of embryos to exogenous RA induces a dramatic anterior expansion of the number of pharyngeal teeth that later form and shifts anteriorly the expression patterns of genes normally expressed in the posterior tooth-forming region, such as pitx2 and dlx2b. After RA exposure, we also observed a correlation between cartilage malformations and ectopic tooth induction, as well as abnormal cranial neural crest marker gene expression. Additionally, we observed that the RA-induced zebrafish anterior teeth resemble in pattern and number the dentition of fish species that retain anterior pharyngeal teeth such as medaka but that medaka do not express the aldh1a2 RA-synthesizing enzyme in tooth-forming regions. We conclude that RA is sufficient to induce anterior ectopic tooth development in zebrafish where teeth were lost in evolution, potentially by altering neural crest cell development, and that changes in the location of RA synthesis correlate with evolutionary changes in vertebrate dentitions.
authors.affiliation: Department of Biology, Bowdoin College, 6500 College Station, Brunswick, ME 04011, USA.
authors.forename: Pawat
authors.initials: P
authors.lastname: Seritrakul
authors.forename: Eric
authors.initials: E
authors.lastname: Samarut
authors.forename: Tenzing T S
authors.initials: TT
authors.lastname: Lama
authors.forename: Yann
authors.initials: Y
authors.lastname: Gibert
authors.forename: Vincent
authors.initials: V
authors.lastname: Laudet
authors.forename: William R
authors.initials: WR
authors.lastname: Jackman
mesh_terms: D000080924:Aldehyde Dehydrogenase 1 Family; D000818:Animals; D030801:Animals, Genetically Modified; D005075:Biological Evolution; D004625:Embryo, Nonmammalian / Q000187:drug effects* / Q000196:embryology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D017403:In Situ Hybridization; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D010614:Pharynx; D050697:Retinal Dehydrogenase / Q000235:genetics / Q000378:metabolism; D055758:SOX9 Transcription Factor / Q000235:genetics / Q000378:metabolism; D014070:Tooth / Q000187:drug effects* / Q000196:embryology / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*; D015027:Zebrafish / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D018398:Homeodomain Proteins; D007527:Isoenzymes; C507321:LEF1 protein, zebrafish; C572614:Pitx2 protein, zebrafish; D055758:SOX9 Transcription Factor; C504918:Sox9a protein, zebrafish; D014157:Transcription Factors; D029961:Zebrafish Proteins; C489127:hoxb5a protein, zebrafish; D049452:Green Fluorescent Proteins; D014212:Tretinoin; D000080924:Aldehyde Dehydrogenase 1 Family; D050697:Retinal Dehydrogenase