Cnidarian Hydra polyps escape senescence, most likely due to the robust activity of their three stem cell populations. These stem cells continuously self-renew in the body column and differentiate at the extremities following a tightly coordinated spatial pattern. Paul Brien showed in 1953 that in one particular species, Hydra oligactis, cold-dependent sexual differentiation leads to rapid aging and death. Here, we review the features of this inducible aging phenotype. These cellular alterations, detected several weeks after aging was induced, are characterized by a decreasing density of somatic interstitial cell derivatives, a disorganization of the apical nervous system, and a disorganization of myofibers of the epithelial cells. Consequently, tissue replacement required to maintain homeostasis, feeding behavior, and contractility of the animal are dramatically affected. Interestingly, this aging phenotype is not observed in all H. oligactis strains, thus providing a powerful experimental model for investigations of the genetic control of aging. Given the presence in the cnidarian genome of a large number of human orthologs that have been lost in ecdysozoans, such approaches might help uncover novel regulators of aging in vertebrates.

中文翻译：

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Hydra，一个强大的衰老研究模型

刺胞动物九头蛇息肉逃脱衰老，很可能是由于其三种干细胞群的强大活性。这些干细胞在体柱中不断自我更新，并按照紧密协调的空间模式在四肢分化。保罗·布赖恩 (Paul Brien) 在 1953 年表明，在一种特殊的物种中，Hydra oligactis，依赖寒冷的性别分化会导致快速衰老和死亡。在这里，我们回顾了这种可诱导衰老表型的特征。在诱导衰老数周后检测到的这些细胞改变的特征是体细胞间质细胞衍生物的密度降低、顶端神经系统的紊乱和上皮细胞的肌纤维的紊乱。因此，维持体内平衡、进食行为、和动物的收缩性受到显着影响。有趣的是，并非在所有寡头嗜血杆菌菌株中都观察到这种衰老表型，因此为研究衰老的遗传控制提供了强大的实验模型。鉴于在蜕皮动物中丢失的大量人类直系同源物存在于刺胞动物基因组中，这种方法可能有助于揭示脊椎动物衰老的新调节剂。