Department of Developmental Biology, Johann Friedrich Blumenbach Institute of Zoology and Anthropology, Georg-August-University, 37077 Göttingen, Germany.
Dev Biol. 2010 Feb 1;338(1):107-16. doi: 10.1016/j.ydbio.2009.11.010. Epub 2009 Nov 12.
The insect head is composed of several segments. During embryonic development, the segments fuse to form a rigid head capsule where obvious segmental boundaries are lacking. Hence, the assignment of regions of the insect head to specific segments is hampered, especially with respect to dorsal (vertex) and lateral (gena) parts. We show that upon Tribolium labial (Tc-lab) knock down, the intercalary segment is deleted but not transformed. Furthermore, we find that the intercalary segment contributes to lateral parts of the head cuticle in Tribolium. Based on several additional mutant and RNAi phenotypes that interfere with gnathal segment development, we show that these segments do not contribute to the dorsal head capsule apart from the dorsal ridge. Opposing the classical view but in line with findings in the vinegar fly Drosophila melanogaster and the milkweed bug Oncopeltus fasciatus, we propose a "bend and zipper" model for insect head capsule formation.
昆虫的头部由几个体节组成。在胚胎发育过程中，这些体节融合形成一个刚性的头壳，缺乏明显的体节边界。因此，昆虫头部区域的分配到特定的体节受到阻碍，特别是对于背部（顶点）和侧面（侧区）部分。我们发现，在 Tc-lab 敲低后，间节被删除但没有转化。此外，我们发现间节有助于三化螟头部外骨骼的侧面部分。基于几个额外的突变体和 RNAi 表型，这些表型干扰了颚体节的发育，我们表明这些节段除了背嵴外，并不参与头部背壳。与经典观点相反，但与在醋蝇果蝇和乳草盲蝽中的发现一致，我们提出了一个“弯曲和拉链”模型，用于昆虫头壳的形成。
