Department of Life Systems, Institute of Technology and Science, University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City 770-8506, Japan.
Dev Growth Differ. 2012 Feb;54(2):227-40. doi: 10.1111/j.1440-169X.2011.01325.x. Epub 2012 Feb 20.
In the cricket Gryllus bimaculatus, a hemimetabolous insect, the compound eyes begin to form in the embryo and increase 5-6 fold in size during the postembryonic development of the nymphal stage. Retinal stem cells in the anteroventral proliferation zone (AVPZ) of the nymphal eye proliferate to increase retinal progenitors, which then differentiate to form new ommatidia in the anterior region of the eye. However, mechanisms underlying this type of eye formation have not been well elucidated yet. Here, we found that the homologues of the retinal determination transcription factor genes of eyes absent (eya) and sine oculis (so) are expressed during the cricket embryonic eye formation. eya is also expressed intensely in the AVPZ of the nymphal eye. To explore their functions, we performed knockdown by RNA interference (RNAi). Knockdown of Gb'eya resulted in loss of the embryonic eye. In the nymphal eye, RNAi against Gb'eya or Gb'so impaired retinal morphology by apparently transforming cornea structures into head cuticle. These results imply that Gb'eya and Gb'so are essential for the differentiation of the retinal progenitor cells and maintaining retinal structures during eye development.
在半变态昆虫蟋蟀 Gryllus bimaculatus 中，复眼在胚胎中开始形成，并在若虫阶段的胚胎后发育过程中增大 5-6 倍。若虫眼的前腹侧增殖区 (AVPZ) 中的视网膜干细胞增殖以增加视网膜祖细胞，然后这些祖细胞分化为眼的前区形成新的小眼。然而，这种眼睛形成的机制尚未得到很好的阐明。在这里，我们发现无眼（eya）和 sine oculis (so) 的视网膜决定转录因子基因的同源物在蟋蟀胚胎眼睛形成过程中表达。eya 在若虫眼的 AVPZ 中也强烈表达。为了探索它们的功能，我们通过 RNA 干扰 (RNAi) 进行了敲低。Gb'eya 的敲低导致胚胎眼缺失。在若虫眼，针对 Gb'eya 或 Gb'so 的 RNAi 通过明显将角膜结构转化为头部外骨骼来破坏视网膜形态。这些结果表明 Gb'eya 和 Gb'so 对于视网膜祖细胞的分化以及在眼睛发育过程中维持视网膜结构是必不可少的。
