Zebrafish and Medaka: new model organisms for modern biomedical research

Abstract

Although zebrafish (Danio rerio) and medaka (Oryzias latipes) are primitive vertebrates, they have several advantages over other model animals. For example, they are fecund and light can control their ovulation. Spawning takes place frequently and no limitation in their spawning season. Microinjection of fertilized eggs is easily accessible and relatively cheap. Their embryos are transparent, making it easy to monitor the dynamic gene expression in various tissues and organs in vivo without the need to sacrifice the experimental subjects. Their genome sizes are approximately 20 to 40 % of the mammalian genome, making them the only vertebrates available for large-scale mutagenesis. Their maturation time takes only 2?~?3 months, which is relatively less laborious and time-saving for generating transgenic lines. In addition, many routine techniques of molecular biology and genetics, including knock-in, knockdown and knockout, are well developed in the model fish. Therefore, zebrafish and medaka are new excellent animal systems for the study of vertebrate-specific biology in vivo.