日本研究人员在美国《国家科学院院刊》网络版上报告说,他们利用新开发的冷冻保存技术,在虹鳟体内培养出山女鳟的精子和卵子,并且利用这些精子和卵子繁殖出了山女鳟。
研究小组带头人、东京海洋大学教授吉崎悟朗认为,这项“借腹生鱼”技术有望使永久保存濒危物种成为可能。
东京海洋大学的研究人员向山女鳟的精巢注入保存液,然后用液氮冷冻。约两个月后解冻,从中提取出能演变成精子的精原细胞,将其注入虹鳟幼鱼的精巢和卵巢内。之前,这些刚出生不久的虹鳟经过不育处理,无法生成精子和卵子,且免疫功能尚未发育,所以移植异种细胞后也不会出现排异反应。
随着虹鳟幼鱼的生长,雄虹鳟的精巢内出现了山女鳟的精子,雌虹鳟的卵巢内出现了山女鳟的卵子。不过研究人员表示,本来应该发育为精子的精原细胞如何发育成卵子的机制尚不清楚。
研究人员对精子与卵子进行人工授精,成功繁育出了山女鳟。此外,他们借助同样的技术,用虹鳟和白点鲑的冷冻精巢,分别借对方之腹,也取得了成功。(生物谷Bioon.com)
doi: 10.1073/pnas.1218468110
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Generation of functional eggs and sperm from cryopreserved whole testes
Seungki Lee, Yoshiko Iwasaki, Shinya Shikina, and Goro Yoshizaki1
The conservation of endangered fish is of critical importance. Cryobanking could provide an effective backup measure for use in conjunction with the conservation of natural populations; however, methodology for cryopreservation of fish eggs and embryos has not yet been developed. The present study established a methodology capable of deriving functional eggs and sperm from frozen type A spermatogonia (ASGs). Whole testes taken from rainbow trout were slowly frozen in a cryomedium, and the viability of ASGs within these testes did not decrease over a 728-d freezing period. Frozen-thawed ASGs that were intraperitoneally transplanted into sterile triploid hatchlings migrated toward, and were incorporated into, recipient genital ridges. Transplantability of ASGs did not decrease after as much as 939 d of cryopreservation. Nearly half of triploid recipients produced functional eggs or sperm derived from the frozen ASGs and displayed high fecundity. Fertilization of resultant gametes resulted in the successful production of normal, frozen ASG-derived offspring. Feasibility and simplicity of this methodology will call for an immediate application for real conservation of endangered wild salmonids.