Identification and Ocular Expression of Zebrafish Laminin Alpha 1 Gene

Purpose: To report a sequence and expression of zebrafish laminin alpha 1. Laminins are components of all basement membranes and have well demonstrated roles in diverse developmental processes including eye formation. Methods: Sequences homologous to mammalian laminin alpha 1 were identified by sequence comparison using BLASTN/X engines and zebrafish genome database available at Sanger Institute. Oligonucleotides were designed and used to amplify overlapping fragments of zebrafish laminin alpha 1 gene from embryonic cDNA. Expression was studied by RT-PCR and in situ hybridization. Results: A 9-kb cDNA contig containing putative laminin alpha 1 reading frame has been identified. The zlama1 contig demonstrated overall 63% identity at amino acid level with the human laminin alpha 1 sequence with identity level varying from 43% to 90% for some regions. RT-PCR experiments identified zlama1 transcript in zebrafish embryos starting from one-cell stage with the most abundant level observed in 14-18 hour embryos. Expression diminished in 72-hour embyos and remained low at later stages. In adult fish, low levels of zlama1 were detected in eye but not other tissues. The zlama1 transcript localized to the lens during eye development by in situ hybridization. Conclusions: A new zebrafish gene homologous to laminin alpha 1 has been identified. The zlama1 is expressed during lens development and in adult eye. The role of this gene in embryonic development will be investigated by morpholino-mediated knockdown experiments and mutant analysis.