A Stable Thoracic Hox Code and Epimorphosis Characterize Posterior Regeneration in Capitella teleta.
A Stable Thoracic Hox Code and Epimorphosis Characterize Posterior Regeneration in Capitella teleta.
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DOI：
10.1371/journal.pone.0149724
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Seaver EC
中科院分区：
文献类型：
--
作者：
de Jong DM;Seaver EC
再生，即在创伤性损伤后替换失去的组织和身体部位的能力，广泛存在于动物的生命树中。再生可以通过重塑预先存在的组织、通过细胞分裂添加新细胞或两者的组合来发生。我们描述了环节动物 Capitella teleta 后部再生的分期系统，并使用 C. teleta Hox 基因代码作为沿前后轴再生组织的区域身份标记。在动物不同后部区域截肢后，胚基形成，两天后，通过 EdU 掺入检测到增殖细胞，表明在 C. teleta 后部再生过程中发生了外态。神经突迅速延伸到胚基中，并在截肢后约 7 天出现新神经节之前逐渐组织成离散的神经。原位杂交显示，所检测的 10 个 Hox 基因中有 7 个在胚基中表达，表明在新形成组织的模式化中发挥作用，尽管没有检测到空间或时间共线性。我们假设截肢后，先前存在的片段中的 Hox 基因表达将按比例重新组织，而剩余的片段将表达完整的 Hox 基因套件。令人惊讶的是，在多个轴向位置截肢后，大多数 Hox 基因在预先存在的组织的神经节中表现出稳定的表达模式，表明节段同一性的总体稳定性。然而，CapI-lox4、CapI-lox2 和 CapI-Post2 这三个 Hox 基因各自将其前部表达边界移动一段，并且每次移动都包括神经节中的一部分细胞。这种表达方式的转变取决于截肢的轴向位置。在 C. teleta 中，胸节表现出稳定的位置特征，但形态轴有限，这与其他一些环节动物、涡虫和无腔扁虫再生过程中发生的广泛的身体重塑形成鲜明对比。
Regeneration, the ability to replace lost tissues and body parts following traumatic injury, occurs widely throughout the animal tree of life. Regeneration occurs either by remodeling of pre-existing tissues, through addition of new cells by cell division, or a combination of both. We describe a staging system for posterior regeneration in the annelid, Capitella teleta, and use the C. teleta Hox gene code as markers of regional identity for regenerating tissue along the anterior-posterior axis. Following amputation of different posterior regions of the animal, a blastema forms and by two days, proliferating cells are detected by EdU incorporation, demonstrating that epimorphosis occurs during posterior regeneration of C. teleta. Neurites rapidly extend into the blastema, and gradually become organized into discrete nerves before new ganglia appear approximately seven days after amputation. In situ hybridization shows that seven of the ten Hox genes examined are expressed in the blastema, suggesting roles in patterning the newly forming tissue, although neither spatial nor temporal co-linearity was detected. We hypothesized that following amputation, Hox gene expression in pre-existing segments would be re-organized to scale, and the remaining fragment would express the complete suite of Hox genes. Surprisingly, most Hox genes display stable expression patterns in the ganglia of pre-existing tissue following amputation at multiple axial positions, indicating general stability of segmental identity. However, the three Hox genes, CapI-lox4, CapI-lox2 and CapI-Post2, each shift its anterior expression boundary by one segment, and each shift includes a subset of cells in the ganglia. This expression shift depends upon the axial position of the amputation. In C. teleta, thoracic segments exhibit stable positional identity with limited morphallaxis, in contrast with the extensive body remodeling that occurs during regeneration of some other annelids, planarians and acoel flatworms.