Abstract
PaxB from Tripedalia cystophora, a cubomedusan jellyfish possessing complex eyes (ocelli), was characterized. PaxB, the only Pax gene found in this cnidarian, is expressed in the larva, retina, lens, and statocyst. PaxB contains a Pax2/5/8-type paired domain and octapeptide, but a Pax6 prd-type homeodomain. Pax2/5/8-like properties of PaxB include a DNA binding specificity of the paired domain, activation and inhibitory domains, and the ability to rescue spa(pol), a Drosophila Pax2 eye mutant. Like Pax6, PaxB activates jellyfish crystallin and Drosophila rhodopsin rh6 promoters and induces small ectopic eyes in Drosophila. Pax6 has been considered a "master" control gene for eye development. Our data suggest that the ancestor of jellyfish PaxB, a PaxB-like protein, was the primordial Pax protein in eye evolution and that Pax6-like genes evolved in triploblasts after separation from Cnidaria, raising the possibility that cnidarian and sophisticated triploblastic eyes arose independently.
MeSH terms
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Amino Acid Sequence
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Animals
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Animals, Genetically Modified
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Binding Sites
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Biological Evolution*
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Cnidaria / anatomy & histology
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Cnidaria / genetics*
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Cnidaria / physiology
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Crystallins / genetics
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Crystallins / metabolism
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Drosophila Proteins*
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Drosophila melanogaster / anatomy & histology
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Drosophila melanogaster / genetics
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Drosophila melanogaster / physiology
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Eye / growth & development*
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Eye Proteins
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Genes, Reporter
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Homeodomain Proteins / genetics
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Homeodomain Proteins / metabolism*
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Molecular Sequence Data
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Ocular Physiological Phenomena
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PAX2 Transcription Factor
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PAX6 Transcription Factor
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Paired Box Transcription Factors
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Phenotype
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Photoreceptor Cells, Invertebrate / physiology
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Promoter Regions, Genetic
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Proteins / metabolism
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Recombinant Fusion Proteins / metabolism
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Repressor Proteins / genetics
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Repressor Proteins / metabolism*
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Rhodopsin / genetics
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Rhodopsin / metabolism
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Sequence Alignment
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Transcriptional Activation
Substances
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Crystallins
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DNA-Binding Proteins
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Drosophila Proteins
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Eye Proteins
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Homeodomain Proteins
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PAX2 Transcription Factor
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PAX6 Transcription Factor
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Paired Box Transcription Factors
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Pax-B protein, Podocoryne carnea
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Proteins
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Recombinant Fusion Proteins
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Repressor Proteins
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Rh6 protein, Drosophila
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Transcription Factors
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Rhodopsin