Comparative analysis of Pax-6 sequence and expression in the eye development of the blind cave fish Astyanax fasciatus and its epigean conspecific.
The Pax-6 gene encodes a transcription factor essential for eye development in a wide range of animal phyla. In order to elucidate a possible role of Pax-6 in the eye regression of a blind cave form of the freshwater fish Astyanax fasciatus (Characidae, Teleostei) we investigated the expression of Pax-6 in eyes and brains of different larval stages by in situ hybridization. Pattern, strength, and time course of Pax-6 expression were not altered in the tissues of the cave form when compared to the epigean form. Pax-6 was even expressed in the highly degenerated eyes of late larval stages of the cave form. Comparative sequence analysis of Pax-6 cDNA clones of both forms of Astyanax fasciatus showed the complete integrity of cave fish Pax-6 mRNA. These results suggest that Pax-6 is not involved in the evolutionary process of eye degeneration in this model system of cave-living fishes. Comparison of the Astyanax Pax-6 cDNA with the other available fish Pax-6 sequence from zebrafish revealed putative fish-specific regions of homology. A stretch of 19 N-terminal amino acids is nearly identical on the nucleotide and amino acid levels in both fish species but not present in all other known Pax-6 sequences.
Behrens
M
M
Institut für Zellbiochemie und klinische Neurobiologie, Universitätskrankenhaus Eppendorf, Hamburg, Germany.
Langecker
T G
TG
Wilkens
H
H
Schmale
H
H
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D001766:Blindness / Q000235:genetics*; D001921:Brain / Q000196:embryology / Q000378:metabolism; D001923:Brain Chemistry; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D005123:Eye / Q000033:anatomy & histology / Q000196:embryology*; D005136:Eye Proteins; D005399:Fishes / Q000235:genetics*; D005618:Fresh Water; D015870:Gene Expression; D015723:Gene Library; D055593:Geological Phenomena; D005844:Geology; D018398:Homeodomain Proteins; D017403:In Situ Hybridization; D007814:Larva; D008969:Molecular Sequence Data; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D012097:Repressor Proteins; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014018:Tissue Distribution; D014157:Transcription Factors / Q000235:genetics*
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors