Latent regeneration abilities persist following recent evolutionary loss in asexual annelids
Latent regeneration abilities persist following recent evolutionary loss in asexual annelids
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DOI：
10.1073/pnas.0907931107
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发表时间：
2010-01-26
影响因子：
11.1
通讯作者：
Sikes, James M.
中科院分区：
文献类型：
--
作者：
Bely, Alexandra E.;Sikes, James M.
再生能力在许多动物门类中一再丧失。然而，由于再生研究几乎完全集中在高度再生的分类群上，或者是对严重分化的再生和非再生分类群之间的比较，对于再生损失是如何发生的，几乎一无所知。在这里，我们表明，在最近进化的再生丧失之后，再生能力仍然可以保持潜在的和仍然被激发的。通过比较再生实验和分子系统学研究，我们发现在环节动物中祖先的头部再生能力已经丧失了三次。环节动物是一组小型水生蠕虫，通常通过分裂无性繁殖。在所有三种不能再生头部的谱系中，蠕虫总是封闭伤口，但无法进入组织替换的第一阶段。然而，尽管在再生损失方面存在粗略的趋同，但对其中两个谱系的进一步调查显示，在有多少再生机制被废除方面，存在着显著的差异。最值得注意的是，在代表这两种血统之一的物种中，在分裂过程中形成的狭窄增殖区内的截肢仍然可以诱导基本上正常的头部再生。因此，在伤口处存在活跃生长组织特有的元素，如激活的干细胞或生长因子，可以绕过再生障碍，使潜在的再生能力得以显现。
Regeneration abilities have been repeatedly lost in many animal phyla. However, because regeneration research has focused almost exclusively on highly regenerative taxa or on comparisons between regenerating and nonregenerating taxa that are deeply diverged, virtually nothing is known about how regeneration loss occurs. Here, we show that, following a recent evolutionary loss of regeneration, regenerative abilities can remain latent and still be elicited. Using comparative regeneration experiments and a molecular phylogeny, we show that ancestral head regeneration abilities have been lost three times among naidine annelids, a group of small aquatic worms that typically reproduce asexually by fission. In all three lineages incapable of head regeneration, worms consistently seal the wound but fail to progress to the first stage of tissue replacement. However, despite this coarse-level convergence in regeneration loss, further investigation of two of these lineages reveals marked differences in how much of the regeneration machinery has been abolished. Most notably, in a species representing one of these two lineages, but not in a representative of the other, amputation within a narrow proliferative region that forms during fission can still elicit regeneration of an essentially normal head. Thus, the presence at the wound site of elements characteristic of actively growing tissues, such as activated stem cells or growth factors, may permit blocks to regeneration to be circumvented, allowing latent regeneration abilities to be manifested.