Behrens M, Langecker T G, Wilkens H, Schmale H
Institut für Zellbiochemie und klinische Neurobiologie, Universitätskrankenhaus Eppendorf, Hamburg, Germany.
Mol Biol Evol. 1997 Mar;14(3):299-308. 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.
Pax-6基因编码一种转录因子，它对于多种动物门类的眼睛发育至关重要。为了阐明Pax-6在淡水鱼墨西哥丽脂鲤（脂鲤科，硬骨鱼纲）的盲穴居形态的眼睛退化过程中可能发挥的作用，我们通过原位杂交研究了不同幼体阶段眼睛和大脑中Pax-6的表达情况。与地表形态相比，穴居形态组织中Pax-6表达的模式、强度和时间进程并未改变。Pax-6甚至在穴居形态晚期幼体高度退化的眼睛中也有表达。对两种形态的墨西哥丽脂鲤的Pax-6 cDNA克隆进行比较序列分析，结果显示穴居鱼Pax-6 mRNA完全完整。这些结果表明，在这个穴居鱼类模型系统中，Pax-6不参与眼睛退化的进化过程。将墨西哥丽脂鲤的Pax-6 cDNA与斑马鱼的其他可用鱼类Pax-6序列进行比较，发现了假定的鱼类特异性同源区域。两种鱼类在核苷酸和氨基酸水平上，19个N端氨基酸的一段序列几乎相同，但在所有其他已知的Pax-6序列中不存在。
