Abstract
Purpose: :
We have previously demonstrated the similarity of corneas between zebrafish and human and systematically studied the normal corneal development and differentiation, indicating that zebrafish is a suitable animal model for the genetic analysis of corneal diseases. This study is to further understand the genetic regulation of the zebrafish cornea by gene expression analysis of this tissue.
Methods: :
Dissected corneas and other tissues from the adult fish were collected and processed for RNA isolation. A corneal cDNA library was constructed from the RNA of the isolated corneas. House–keeping genes were subtracted from the cornea by the utilization of non–corneal RNA in a subtractive hybridization experiment. DNA sequence analysis was performed on clones derived from the corneal cDNA library and the subtractive library. Bioinformatics tools and in situ hybridization were used for analysis of zebrafish corneal genes and determination of tissue–specificity of the selected cDNA clones.
Results: :
The corneal cDNA library contained 6.5x106 independent clones with an average insert of 1.2 kb and less than 1% non–recombinant clones. DNA sequence analysis indicated that majority of clones contained unique sequences. Nearly 40% of unique sequences found no homologous genes/ESTs/predicted genes in genomic databases (GenBank, Emsembl, and the NEIBank). About 60% of unique sequences were located into the zebrafish genome by database analysis, indicating that genome location of novel corneal genes can be determined simply by electronic mapping strategy. Comparison of global gene expression in the zebrafish cornea to that in the human cornea found important similarities and differences. The data are available through the NEIBank web site. In addition, sequence analysis and in situ hybridization identified several cornea–specific genes.
Conclusions: :
The corneal cDNA is an excellent resource for gene expression profiling studies and identifying new genes from the fish cornea. Cornea–specific genes identified in this study are good candidates of corneal diseases and provide unique opportunities to analyze the genetic control of corneal development and differentiation. Zebrafish is a promising animal model for the studies of cornea.
Keywords: cornea: basic science • gene/expression • genetics