Morioka Sho, Mohanty-Hejmadi Priyambada, Yaoita Yoshio, Tazawa Ichiro
Amphibian Research Center, Graduate School of Science, Hiroshima University, Higashihiroshima, Hiroshima, Japan.
Department of Zoology, Utkal University, Bhubaneswar, Orissa, India.
Dev Growth Differ. 2018 Aug;60(6):365-376. doi: 10.1111/dgd.12547.
Anuran tadpoles can regenerate their tails after amputation. However, they occasionally form ectopic limbs instead of the lost tail part after vitamin A treatment. This is regarded as an example of a homeotic transformation. In this phenomenon, the developmental fate of the tail blastema is apparently altered from that of a tail to that of limbs, indicating a realignment of positional information in the blastema. Morphological observations and analyses of the development of skeletal elements during the process suggest that positional information in the blastema is rewritten from tail to trunk specification under the influence of vitamin A, resulting in limb formation. Despite the extensive information gained from morphological observations, a comprehensive understanding of this phenomenon also requires molecular data. We review previous studies related to anuran homeotic transformation. The findings of these studies provide a basis for evaluating major hypotheses and identifying molecular data that should be prioritized in future studies. Finally, we argue that positional information for the tail blastema changes to that for a part of the trunk, leading to homeotic transformations. To suggest this hypothesis, we present published data that favor the rewriting of positional information.
无尾两栖类蝌蚪在截肢后能够再生其尾巴。然而，在维生素A处理后，它们偶尔会形成异位肢体而非缺失的尾巴部分。这被视为同源异型转化的一个例子。在这种现象中，尾芽的发育命运显然从尾巴转变为肢体，这表明芽中位置信息的重新排列。在此过程中对骨骼元素发育的形态学观察和分析表明，在维生素A的影响下，芽中的位置信息从尾巴规格被重写为躯干规格，从而导致肢体形成。尽管从形态学观察中获得了大量信息，但对这一现象的全面理解还需要分子数据。我们回顾了与无尾两栖类同源异型转化相关的先前研究。这些研究的结果为评估主要假说以及确定未来研究中应优先考虑的分子数据提供了基础。最后，我们认为尾芽的位置信息转变为躯干一部分的位置信息，从而导致同源异型转化。为了提出这一假说，我们展示了支持位置信息重写的已发表数据。
