Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan.
Misaki Marine Biological Station, Graduate School of Science, The University of Tokyo, Miura, Kanagawa, 238-0225, Japan.
Development. 2019 Mar 4;146(5):dev171942. doi: 10.1242/dev.171942.
In social insects, interactions among colony members trigger caste differentiation with morphological modifications. In termite soldier differentiation, the mandible size considerably increases through two moltings (via the presoldier stage) under the control of juvenile hormone (JH). Regulatory genes are predicted to provide patterning information that induces the mandible-specific cell proliferation. To identify factors responsible for the mandibular enlargement, expression analyses of 18 candidate genes were carried out in the termite Among those, (), which identifies the intermediate domain along the proximodistal appendage axis, showed mandible-specific upregulation prior to the molt into presoldiers, which can explain the pattern of cell proliferation for the mandibular elongation. Knockdown of by RNAi reduced the mandibular length and distorted its morphology. Furthermore, the epistatic relationships among , , () and were revealed by combined RNAi and qRT-PCR analyses, suggesting that is regulated by , downstream of the JH and insulin signaling pathways. Thus, caste-specific morphogenesis is controlled by interactions between the factors that provide spatial information and physiological status.
在社会性昆虫中，群体成员之间的相互作用会引发形态改变的级型分化。在白蚁兵蚁的分化过程中，通过两次蜕皮（通过预兵蚁阶段），在保幼激素（JH）的控制下，下颚大小显著增大。预测调节基因提供形态发生信息，诱导下颚特化细胞增殖。为了确定负责下颚增大的因素，对 18 个候选基因在白蚁中的表达进行了分析。其中，（）沿附肢近-远轴识别中间域，在蜕皮为预兵蚁之前表现出下颚特异性上调，这可以解释下颚伸长的细胞增殖模式。通过 RNAi 敲低 会降低下颚的长度并使其形态扭曲。此外，通过联合 RNAi 和 qRT-PCR 分析揭示了 、 、 （）和 之间的上位性关系，表明 受到 调节，位于 JH 和胰岛素信号通路的下游。因此，特定级型的形态发生受提供空间信息和生理状态的因子之间的相互作用控制。
