even-skipped is not a pair-rule gene but has segmental and gap-like functions in Oncopeltus fasciatus, an intermediate germband insect
even-skipped is not a pair-rule gene but has segmental and gap-like functions in Oncopeltus fasciatus, an intermediate germband insect
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DOI：
10.1242/dev.01807
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发表时间：
2005-05-01
期刊：
影响因子：
4.6
通讯作者：
Kaufman, TC
中科院分区：
文献类型：
--
作者：
Liu, PZ;Kaufman, TC
果蝇的配对规则基因偶跳是启动同色异谱模式所必需的。但果蝇的体节是进化而来的，并不代表大多数昆虫。因此，为了阐明昆虫体节的进化，人们在几个昆虫类群中研究了偶跳配对规则基因的同源物。然而，这些研究大多报道了Eve的表达，而没有报道其功能。本文报道了果蝇偶跳基因同源物的分离、表达和功能。我们发现，在Oncopeltus，甚至跳过条纹的表达启动在一个节段，而不是对规则的模式。Oncopeltus even-skipped的弱RNAi抑制显示没有明显的配对规则样表型，而较强的RNAi抑制显示几乎整个身体的缺失。这些结果表明，在Oncopeltus，偶数跳过是不是作为一个配对规则基因。在几乎所有昆虫中，在其条纹表达之前，even-skipped在保守的宽间隙样结构域中表达，但其功能在很大程度上被忽视。我们发现，这一早期的广泛领域所需的差距基因hunchback和Kruppel的激活。考虑到大的RNAi缺失表型及其对hunchback和Kruppel的调控，even-skipped似乎在Oncopeltus中充当纤维间隙基因，表明它可能在分割中起上游和下游作用。
The pair-rule gene even-skipped is required for the initiation of metameric pattern in Drosophila. But Drosophila segmentation is evolutionarily derived and is not representative of most insects. Therefore, in order to shed light on the evolution of insect segmentation, homologs of the pair-rule gene even-skipped have been studied in several insect taxa. However, most of these studies have reported the expression eve but not its function. We report the isolation, expression and function of the homolog of Drosophila even-skipped from the intermediate germband insect Oncopeltus fasciatus. We find that in Oncopeltus, even-skipped striped expression initiates in a segmental and not pair-rule pattern. Weak RNAi suppression of Oncopeltus even-skipped shows no apparent pair-rule like phenotype, while stronger RNAi suppression shows deletion of nearly the entire body. These results suggest that in Oncopeltus, even-skipped is not acting as a pair-rule gene. In almost all insects, prior to its striped expression, even-skipped is expressed in a conserved broad gap-like domain but its function has been largely ignored. We find that this early broad domain is required for activation of the gap genes hunchback and Kruppel. Given the large RNAi deletion phenotype and its regulation of hunchback and Kruppel, even-skipped seems to act as an fiber-gap gene in Oncopeltus, indicating that it may have both upstream and downstream roles in segmentation.