Comparative analysis of Pax-6 sequence and expression in the eye development of the blind cave fish Astyanax fasciatus and its epigean conspecific

• Published in: Molecular biology and evolution 1997-03, Vol.14 (3), p.299-308
• Main Authors: Behrens, M, Langecker, T G, Wilkens, H, Schmale, H
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Astyanax fasciatus; Base Sequence; Biological Evolution; Blindness - genetics; Brain - embryology; Brain - metabolism; Brain Chemistry; Danio rerio; DNA, Complementary - genetics; DNA-Binding Proteins - genetics; Eye - anatomy & histology; Eye - embryology; Eye Proteins; Fishes - genetics; Fresh Water; Freshwater; Gene Expression; Gene Library; Geological Phenomena; Geology; Homeodomain Proteins; In Situ Hybridization; Larva; Molecular Sequence Data; Paired Box Transcription Factors; PAX6 Transcription Factor; Polymerase Chain Reaction; Repressor Proteins; RNA, Messenger - analysis; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Time Factors; Tissue Distribution; Transcription Factors - genetics
• ISSN: 0737-4038; 1537-1719
• DOI: 10.1093/oxfordjournals.molbev.a025765

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.