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Speed regulation of genetic cascades allows for evolvability in the body plan specification of insects
Proceedings of the National Academy of Sciences of the United States of America ( IF 11.1 ) Pub Date : 2017-09-25 00:00:00 , DOI: 10.1073/pnas.1702478114
Xin Zhu 1 , Heike Rudolf 2 , Lucas Healey 2 , Paul François 3 , Susan J. Brown 1 , Martin Klingler 2 , Ezzat El-Sherif 2
Affiliation  

During the anterior−posterior fate specification of insects, anterior fates arise in a nonelongating tissue (called the “blastoderm”), and posterior fates arise in an elongating tissue (called the “germband”). However, insects differ widely in the extent to which anterior−posterior fates are specified in the blastoderm versus the germband. Here we present a model in which patterning in both the blastoderm and germband of the beetle Tribolium castaneum is based on the same flexible mechanism: a gradient that modulates the speed of a genetic cascade of gap genes, resulting in the induction of sequential kinematic waves of gap gene expression. The mechanism is flexible and capable of patterning both elongating and nonelongating tissues, and hence converting blastodermal to germband fates and vice versa. Using RNAi perturbations, we found that blastodermal fates could be shifted to the germband, and germband fates could be generated in a blastoderm-like morphology. We also suggest a molecular mechanism underlying our model, in which gradient levels regulate the switch between two enhancers: One enhancer is responsible for sequential gene activation, and the other is responsible for freezing temporal rhythms into spatial patterns. This model is consistent with findings in Drosophila melanogaster, where gap genes were found to be regulated by two nonredundant “shadow” enhancers.

中文翻译:

基因级联的速度调节允许昆虫在人体计划规范中发展

在昆虫的前后命运特征期间,前命运出现在非伸长组织(称为胚盘)中,后命运出现在伸长组织(称为胚芽)中。但是,昆虫在胚盘与种系中指定前后命运的程度差异很大。在这里,我们提出一个模型,其中在甲壳虫Tribolium castaneum的胚盘和胚带中都进行构图基于相同的灵活机制:梯度调节间隙基因的遗传级联的速度,从而导致间隙基因表达的连续运动波的诱导。该机制是灵活的,并且能够对伸长和非伸长的组织进行图案化,从而将胚盘命运转变为种系命运,反之亦然。使用RNAi扰动,我们发现胚盘命运可以转移到种带,并且胚带命运可以以胚盘状形态产生。我们还提出了我们模型的基础分子机制,其中梯度水平调节两种增强子之间的转换:一种增强子负责顺序基因激活,另一种负责将时间节律冻结为空间模式。该模型与果蝇(Drosophila melanogaster),发现缺口基因受两种非冗余的“阴影”增强子的调控。
更新日期:2017-09-26
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