日本一個研究小組日前發(fā)現，在雌鳉魚的卵巢內存在可發(fā)育成鳉魚卵的干細胞。有關成果已經刊登在一期的美國《科學》雜志網絡版上。

這一成果是日本自然科學研究機構基礎生物學研究所的研究人員獲得的。基礎生物學研究所日前發(fā)表公告說，在脊椎動物中，已經發(fā)現雄性的精巢中存在發(fā)育成精子的干細胞，但是在卵巢中發(fā)現會發(fā)育成卵的干細胞則屬世界。

研究小組對雌性鳉魚進行基因操作，使其卵巢內的卵發(fā)出紅光，結果發(fā)現了很多即將發(fā)育為卵的細胞。利用綠色熒光蛋白質給這些細胞做上標記以后，研究人員發(fā)現許多新形成的卵也會發(fā)出綠色熒光，這說明這些細胞的確發(fā)育成了卵，因此這些細胞就是干細。

鳉魚等魚類會大量產卵，但是詳細機制一直沒有弄清。研究小組成員田中實指出，他們的新發(fā)現可能為開發(fā)的養(yǎng)殖技術作出貢獻。

Science DOI: 10.1126/science.1185473

Identification of Germline Stem Cells in the Ovary of the eost Medaka
Shuhei Nakamura,1 Kayo Kobayashi,1 Toshiya Nishimura,1,2 Shin-ichi Higashijima,3,4 Minoru Tanaka1,2,*

Germline stem cells continually produce sperm in vertebrate testes, whereas there is no direct evidence showing that germline stem cells are present in adult vertebrate ovaries. Using transgenic methods and clonal analysis, we identified germline stem cells that supported oogenesis and the production of offspring in the ovaries of adult medaka fish. Early-stage germ cells were localized in clusters along interwoven threadlike cords of sox9b-expressing somatic cells （termed "germinal cradles"） where the germ cells developed. Germline stem cells gave rise to germ cells that divided to produce cysts, which then underwent cell death or separated to form follicles. Our results provide insight into germline stem cell biology of medaka and provide a model system for studying vertebrate stem cell niches.

1 Laboratory of Molecular Genetics for Reproduction, National Institute for Basic Biology, Okazaki 444-8787, Japan.
2 Department of Basic Biology, Graduate University for Advanced Studies （SOKENDAI）, Okazaki, Aichi 444-8585, Japan.
3 National Institutes of Natural Sciences, Okazaki Institute for Integrative Bioscience, National Institute for Physiological Sciences, Okazaki, Aichi 444-8787, Japan.
4 Department of Physiological Sciences, Graduate University for Advanced Studies （SOKENDAI）, Okazaki, Aichi 444-8585, Japan.