Woodhead A D, Setlow R B, Pond V
Natl Cancer Inst Monogr. 1984 May;65:45-52.
The Amazon molly, Poecilia formosa, a small, live-bearing fish native to Texas, has an unusual mode of reproduction that makes it highly suitable for carcinogenicity studies. The species is easy to rear and breed, and withstands handling well. Large broods of young are born, numbering up to 90 when the parent fish are fully grown. The Amazon molly reproduces gynogenetically; eggs are activated after mating with males of closely related species. The male makes no genetic contribution; sperm provides only the stimulus for egg development. The offspring of a female comprise a clone with genotypes identical to that of the mother's so that cell and tissue transplants made between members of the clone are not rejected. We used the Amazon molly as an animal model to show that damage to DNA caused by UV and ionizing radiation and by certain chemicals results in tumor development. Thyroid cells were taken from donor mollies, treated precisely in vitro with the agents, and then injected into homologous recipients. Eight months later, recipient fish had developed large thyroid tumors. The genetic homogeneity of the clone also makes the Amazon molly invaluable in acute or chronic bioassays because variability in the responses of the individual fishes is minimal. Therefore, a limited number will suffice to give statistically significant results. The findings from a study of chronic exposure to asbestos are also described.
亚马孙帆鳉（Poecilia formosa）是一种原产于得克萨斯州的小型卵胎生鱼类，其繁殖方式独特，非常适合用于致癌性研究。该物种易于饲养和繁殖，且耐处理。亲鱼完全长大后能产下大量幼鱼，数量可达90条。亚马孙帆鳉通过雌核生殖进行繁殖；与亲缘关系相近物种的雄鱼交配后，卵被激活。雄鱼不提供遗传物质；精子仅为卵的发育提供刺激。雌鱼的后代构成一个克隆群体，其基因型与母体相同，因此克隆群体成员之间进行的细胞和组织移植不会被排斥。我们以亚马孙帆鳉为动物模型，证明紫外线、电离辐射及某些化学物质对DNA造成的损伤会导致肿瘤形成。从供体帆鳉身上获取甲状腺细胞，在体外精确地用这些试剂进行处理，然后注入同源受体。八个月后，受体鱼长出了大的甲状腺肿瘤。克隆群体的基因同质性也使得亚马孙帆鳉在急性或慢性生物测定中具有极高价值，因为个体鱼反应的变异性极小。因此，数量有限的鱼就足以得出具有统计学意义的结果。文中还描述了一项关于长期接触石棉的研究结果。
