Divergent and conserved roles of extradenticle in body segmentation and appendage formation, respectively, in the cricket Gryllus bimaculatus
Divergent and conserved roles of extradenticle in body segmentation and appendage formation, respectively, in the cricket Gryllus bimaculatus
复制标题
DOI：
10.1016/j.ydbio.2007.09.060
复制
发表时间：
2008-01-01
影响因子：
2.7
通讯作者：
Noji, Sumihare
中科院分区：
文献类型：
--
作者：
Mito, Taro;Ronco, Monica;Noji, Sumihare
蟋蟀Gryllusbimaculatus是一种典型的半变态中间生殖昆虫，其体节和附肢的形成过程不同于果蝇。为了比较它们的发育机制，我们重点研究了果蝇发育调控基因的蟋蟀同源基因，并研究了它们的功能。在这里，我们报告了一个功能分析的蟋蟀直系同源物的extradenticle（Gb'exd）使用胚胎和父母的RNA干扰（RNAi）技术。结果表明：（1）抑制Gb'exd基因的RNAi可导致体节的缺失或融合。尤其是头部，往往受到严重影响。这种缺口样表型可能与早期RNAi胚带中差距基因hunchback和Kruppel的表达减少有关。(2)在附肢中，几个节（podomeres）融合。(3)包括触角在内的头部附属物转变为由至少一个近端足节和几个跗节组成的腿状结构。在附件的缺陷是让人想起果蝇触角盘的大exd克隆所造成的表型。这些发现使我们得出以下结论：（1）Gb'exd是颌部至腹部区域的节段模式化所必需的，在前部区域以间隙基因样方式起作用。(2)Gb'exd在附属物的形成和它们的身份的确定中起着重要的作用，充当在头部附属物与附属物基态之间选择命运的调节开关。虽然Gbexd在附肢模式中的功能在蟋蟀和果蝇之间基本上是保守的，但它在身体分割中的作用可能与果蝇exd不同。(c)2007爱思唯尔公司All rights reserved.
The cricket Gryllus bimaculatus is a typical hemimetabolous intemediate germ insect, in which the processes of segmentation and appendage formation differ from those in Drosophila, a holometabolous long germ insect. In order to compare their developmental mechanisms, we have focused on Gryllus orthologs of the Drosophila developmental regulatory genes and studied their functions. Here, we report a functional analysis of the Gryllus ortholog of extradenticle (Gb'exd) using embryonic and parental RNA interference (RNAi) techniques. We found the following: (1) RNAi suppression of Gb'exd results in the deletion or fusion of body segments. Especially the head was often very severely affected. This gap-like phenotype may be related to reduced expression of the gap genes hunchback and Kruppel in early RNAi germbands. (2) In the appendages, several segments (podomeres) were fused. (3) Head appendages including the antenna were transformed to a leg-like structure consisting of at least one proximal podomere as well as several tarsomeres. The defects in appendages are reminiscent of the phenotype caused by large exd clones in Drosophila antennal discs. These findings led us to the conclusion that (1) Gb'exd is required for segment patterning in the gnathal to abdominal region, acting in a gap gene-like manner in the anterior region. (2) Gb'exd plays important roles in formation of the appendages and the determination of their identities, acting as a regulatory switch that chooses between the fates of head appendages versus the appendage ground state. Although functions of Gbexd in appendage patterning appear fundamentally conserved between Gryllus and Drosophila, its role in body segmentation may differ from that of Drosophila exd. (c) 2007 Elsevier Inc. All rights reserved.