Cloning of the Retinoblastoma cDNA from the Japanese medaka (Oryzias latipes) and preliminary evidence of mutational alterations in chemically-induced retinoblastomas

We have cloned a medaka homolog of the human retinoblastoma (Rb) susceptibility gene. The medaka Rb cDNA encodes a predicted protein of 909 amino acids. DNA sequence analysis with other vertebrate Rb sequences demonstrates that the medaka Rb cDNA is highly conserved in regions of functional importance. An antibody raised against an epitope of the human pRb recognizes the protein product of the medaka Rb gene, detecting a 105 kDa protein in all tissues examined and at differential levels for the stages of embryonic development studied. The sequence reported herein, combined with the high degree of conservation observed in critical domains, has also facilitated a preliminary investigation of the molecular etiology of chemically-induced retinoblastoma. The mutational alterations characterized suggest that medaka may provide a novel model and, thus, provide additional insight into the human retinoblastoma condition