Variation in the Dorsal Gradient Distribution Is a Source for Modified Scaling of Germ Layers in Drosophila
Variation in the Dorsal Gradient Distribution Is a Source for Modified Scaling of Germ Layers in Drosophila
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DOI：
10.1016/j.cub.2013.03.031
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发表时间：
2013-04-22
期刊：
影响因子：
9.2
通讯作者：
Mizutani, Claudia Mieko
中科院分区：
文献类型：
--
作者：
Chahda, Juan Sebastian;Sousa-Neves, Rui;Mizutani, Claudia Mieko
通过形态发生梯度对沿背腹轴的胚层进行规范是研究进化过程中梯度的缩放特性和细胞命运变化的理想模型。对不同昆虫（例如苍蝇和蚱蜢）的经典解剖学研究表明，神经外胚层大小是保守的，并且产生相似数量的同源神经母细胞 [1-3]。相比之下，密切相关的果蝇物种的中胚层结构域差异显着[4]。为了进一步研究果蝇物种胚层扩展的潜在机制，我们量化了 Dorsal (DI)/NF-kappa B 梯度，这是启动中胚层、神经外胚层和外胚层分离的主要形态发生梯度 [5-7]。我们发现不同物种间 Toll 激活的范围存在差异，并发现 DI 在黑腹果蝇同胞物种中以相同的阈值水平激活中胚层基因。我们还表明，DI 梯度分布可以通过核尺寸和堆积密度进行调节。我们认为中胚层尺寸的变化以快速的进化速度发生，并且是定义神经外胚层腹侧边界的重要机制。
Specification of germ layers along the dorsoventral axis by morphogenetic gradients is an ideal model to study scaling properties of gradients and cell fate changes during evolution. Classical anatomical studies in divergent insects (e.g., flies and grasshoppers) revealed that the neuroectodermal size is conserved and originates similar numbers of neuroblasts of homologous identity [1-3]. In contrast, mesodermal domains vary significantly in closely related Drosophila species [4]. To further investigate the underlying mechanisms of scaling of germ layers across Drosophila species, we quantified the Dorsal (DI)/NF-kappa B gradient, the main morphogenetic gradient that initiates separation of the mesoderm, neuroectoderm, and ectoderm [5-7]. We discovered a variable range of Toll activation across species and found that DI activates mesodermal genes at the same threshold levels in melanogaster sibling species. We also show that the DI gradient distribution can be modulated by nuclear size and packing densities. We propose that variation in mesodermal size occurs at a fast evolutionary rate and is an important mechanism to define the ventral boundary of the neuroectoderm.