鱼类的胚胎干细胞

胚胎干细胞(ES)是未分化的细胞培养物，来自动物的早期胚胎。它们能成为稳定的细胞系和长期冻存。在适当的条件下，ES细胞能分化成各种细胞类型，包括生殖细胞。这样，ES细胞就提供了一个有效的纽带，将动物基因组的体外和体内遗传操作连系起来。ES细胞的魅力就由其在产生和分析基因敲除老鼠中显现出来。目前，ES细胞技术仅见之老鼠，因其它脊椎动物的ES细胞的培养和建系难获成功。在鱼类，人们已做了大量的尝试。我们以青鳉(Oryzias latipes)作为建立鱼类ES细胞技术的模式，通过建立并应用无滋养层细胞的培养条件，获得了来自中期囊胚的ES细胞系。青鳉的ES细胞和老鼠的ES细胞有很多共同特征，如二倍体核型、分化潜力和形成嵌合体。因此，在鱼类建立和应用ES细胞技术是可能的。青鳉ES细胞的培养条件已成功地应用到其它鱼类如斑马鱼甚至海水鱼。本文旨在以青鳉为模式，综述获得和应用模式鱼和经济鱼ES细胞的主要进展和前景。

Embryonic stem cells in fish

Embryonic stem (ES) cells are undifferentiated cell cultures derived from early developing embryos of animals. They can be propagated into stable cell lines and cryopreserved. Under appropriate conditions, ES cells can differentiate into all cell types including germ cells. Therefore, ES cells provide a unique tool linking in vitro and in vivo genetic manipulations of animal genomes. ES cells have shown their value in mice in the production and analysis of knockout animals. Because ES cells are elusive in various other vertebrate species, this ES cell technology has so far been limited to mice. Numerous attempts have been made to develop ES cell technology in fish. We used the medaka (Oryzias latipes) as a fish model for the development of ES cell technology. We have established feeder cell-free culture conditions and obtained several ES cell lines from midblastula embryos (MBE). These ES cells show all features of mouse ES cells including a diploid karyotype, the potential for differentiation into various cell types and chimera competence. This indicates that it is possible to develop and utilize ES cell technology in fish. This progress with the medaka has led to the establishment of ES-like cell cultures in other species, including zebrafish and even marine fish species. This review is to highlight the major advances and future prospects for obtaining and utilizing ES cells in model and aquaculture fish species. We focus on the medaka since this is the only vertebrate besides the mouse where ES cell work has been extensively studied.