Henry J Q, Martindale M Q
The Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA.
Dev Biol. 2000 Nov 15;227(2):720-33. doi: 10.1006/dbio.2000.9903.
Lobate ctenophores (tentaculates) generally exhibit a remarkable ability to regenerate missing structures as adults. On the other hand, their embryos exhibit a highly mosaic behavior when cut into halves or when specific cells are ablated. These deficient embryos do not exhibit embryonic regulation, and generate incomplete adult body plans. Under certain conditions, however, these deficient animals are subsequently able to replace the missing structures during the adult phase in a process referred to as "post-regeneration." We have determined that successful post-regeneration can be predicted on the basis of a modified polar coordinate model, and the rules of intercalary regeneration, as defined by French et al. (V. French, P. J. Bryant, and S. V. Bryant, 1976, Science 193, 969-981.) The model makes certain assumptions about the organization of the ctenophore body plan that fit well with what we have determined on the basis of cell lineage fates maps, and their twofold rotational ("biradial") symmetry. The results suggest that cells composing the ctenophore adult body plan possess positional information, which is utilized to reconstruct the adult body plan. More specifically, we have found that the progeny of three specific cell lineages are required to support post-regeneration of the comb rows (the e(1), e(2), and m(1) micromeres). Furthermore, post-regeneration of the comb rows involves a suite of cell-cell inductive interactions, which are similar to those that take place during their embryonic formation. The significance of these findings is discussed in terms of the organization of the ctenophore body plan, and the mechanisms involved in cell fate specification. This situation is also contrasted with that of the atentaculate ctenophores, which are unable to undergo post-regeneration.
叶状栉水母（有触手类）通常表现出作为成体再生缺失结构的非凡能力。另一方面，它们的胚胎在被切成两半或特定细胞被切除时表现出高度嵌合行为。这些有缺陷的胚胎不表现出胚胎调节，而是产生不完整的成体身体结构。然而，在某些条件下，这些有缺陷的动物随后能够在成体阶段通过一个被称为“后期再生”的过程来替换缺失的结构。我们已经确定，成功的后期再生可以根据一个修改后的极坐标模型以及由弗伦奇等人定义的居间再生规则来预测（V. 弗伦奇、P. J. 布赖恩特和S. V. 布赖恩特，1976年，《科学》193卷，969 - 981页）。该模型对栉水母身体结构的组织做出了某些假设，这些假设与我们根据细胞谱系命运图谱以及它们的双重旋转（“双辐射状”）对称性所确定的情况非常吻合。结果表明，构成栉水母成体身体结构的细胞拥有位置信息，这些信息被用于重建成体身体结构。更具体地说，我们发现三个特定细胞谱系的后代是支持栉板行后期再生所必需的（即e(1)、e(2)和m(1)微裂球）。此外，栉板行的后期再生涉及一系列细胞间诱导相互作用，这些相互作用与它们胚胎形成过程中发生的相互作用相似。我们从栉水母身体结构的组织以及细胞命运特化所涉及的机制方面讨论了这些发现的意义。这种情况也与无触手栉水母的情况形成对比，无触手栉水母无法进行后期再生。
