Nishimiya-Fujisawa C, Sugiyama T
Department of Genetics, Graduate University for Advanced Studies, Mishima, Japan.
Dev Biol. 1995 Nov;172(1):324-36. doi: 10.1006/dbio.1995.0026.
Three types of interstitial stem cell subpopulation were isolated from Hydra magnipapillata, and their roles in sex determination were examined. A subpopulation of interstitial stem cells restricted to the sperm differentiation pathway was isolated previously from strain nem-1 (male). Another subpopulation restricted to the egg differentiation pathway was also isolated from the same strain. Hydroxyurea treatment was used for isolation in both cases. "Pseudoepithelial hydra" containing only sperm- or egg-restricted stem cell but no other interstitial stem cell types were maintained by force-feeding for 2 years. Sex reversal from egg- to sperm-restricted stem cells occurred three times during this period. Both of these two stem cell types are numerous in the central gastric region of the pseudoepithelial hydra, but absent in the foot region below the budding zone. Foot tissue was cut out from normal nem-1 polyps (male) and allowed to regenerate. The regenerates produced eggs but no sperm upon sex induction. These and other results suggest that the foot tissue contains multipotent stem cells capable of differentiating into eggs during sexual differentiation. These observations suggest that strain nem-1 (male) contains three types of interstitial stem cell subpopulations: (1) sperm-restricted stem cells, (2) egg-restricted stem cells, and (3) multipotent stem cells capable of differentiating into nerve cells, nematocytes, and eggs. Upon sex induction, however, differentiation of eggs by the latter two types is suppressed, and only sperm are produced by the sperm-restricted stem cells. Evidence is presented which suggests that similar "phenotypic males," which normally only produce sperm but contain the stem cell types capable of differentiating into eggs, occur widely in Hydra magnipapillata. A possible relationship between phenotypic male hydra and hermaphroditic hydra is discussed.
从巨大乳头水螅中分离出三种间充质干细胞亚群，并研究了它们在性别决定中的作用。之前已从nem-1品系（雄性）中分离出一个局限于精子分化途径的间充质干细胞亚群。同样从该品系中也分离出了另一个局限于卵子分化途径的亚群。在这两种情况下均使用羟基脲处理进行分离。通过强制喂食维持了仅含有精子或卵子限制干细胞但没有其他间充质干细胞类型的“假上皮水螅”达两年之久。在此期间，发生了三次从卵子限制干细胞到精子限制干细胞的性别逆转。这两种干细胞类型在假上皮水螅的中央胃区域数量众多，但在出芽区下方的足部区域不存在。从正常的nem-1息肉（雄性）中切下足部组织并使其再生。再生体在进行性别诱导时产生卵子但不产生精子。这些以及其他结果表明，足部组织含有在性别分化过程中能够分化为卵子的多能干细胞。这些观察结果表明，nem-1品系（雄性）包含三种间充质干细胞亚群：（1）精子限制干细胞，（2）卵子限制干细胞，以及（3）能够分化为神经细胞、刺细胞和卵子的多能干细胞。然而，在进行性别诱导时，后两种类型的干细胞对卵子的分化受到抑制，只有精子限制干细胞产生精子。有证据表明，类似的“表型雄性”，即通常只产生精子但含有能够分化为卵子的干细胞类型，在巨大乳头水螅中广泛存在。文中还讨论了表型雄性水螅与雌雄同体水螅之间可能的关系。
