Grasshopper hunchback expression reveals conserved and novel aspects of axis formation and segmentation.
Grasshopper hunchback expression reveals conserved and novel aspects of axis formation and segmentation.
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发表时间：
2001-09
期刊：
影响因子：
4.6
通讯作者：
N. Patel;D. Hayward;S. Lall;Nicole Pirkl;Daniel DiPietro;Eldon E. Ball
中科院分区：
文献类型：
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作者：
N. Patel;D. Hayward;S. Lall;Nicole Pirkl;Daniel DiPietro;Eldon E. Ball
虽然已经证明，在果蝇和美洲血吸虫（蚱蜢）中，节段极性基因（如enrailed）的表达模式是相似的，但配对规则基因（如偶跳）的表达模式在这些物种之间并不保守。这可能表明配对规则基因表达上游的因子在昆虫物种中并不保守。我们发现，尽管如此，果蝇gap基因hunchback的表达的许多方面与其在蚱蜢S中的直系同源物是共享的。americana和L.移民。我们已经分析了mRNA和蛋白质的表达在发展过程中，发现蝗虫驼背的直系同源物似乎有一个保守的作用，在早期轴向图案的胚芽原基和规格的颚和胸部原基。此外，不同的阶梯式表达水平的驼背在颚/胸域表明，蚱蜢驼背可能会采取行动，在浓度依赖性的方式（如在果蝇），虽然形态发生活动是不成立的扩散，形成一个平滑的梯度。轴向图案功能似乎完全由合子hunchback执行，这是与果蝇的根本区别，在果蝇中，母亲和合子hunchback扮演多余的角色。在蚱蜢，母亲驼背活动提供统一的胚胎蛋白质，我们建议，担任一个独特的作用，区分胚胎从胚外细胞沿着的前后轴从一开始的发展-一个区别在果蝇沿着背腹轴后来在发展。后来hunchback在腹部节的表达是保守的，就像在神经系统中的模式一样，在果蝇和蚱蜢中，hunchback在胚外细胞的一个子集中表达。因此，虽然驼背表达的预期领域是保守的血吸虫，我们已经发现了令人惊讶的和根本的差异，轴向图案，并确定了一个以前未报道的领域的表达，在果蝇，这表明保护的功能，在胚胎外图案。
While the expression patterns of segment polarity genes such as engrailed have been shown to be similar in Drosophila melanogaster and Schistocerca americana (grasshopper), the expression patterns of pair-rule genes such as even-skipped are not conserved between these species. This might suggest that the factors upstream of pair-rule gene expression are not conserved across insect species. We find that, despite this, many aspects of the expression of the Drosophila gap gene hunchback are shared with its orthologs in the grasshoppers S. americana and L. migratoria. We have analyzed both mRNA and protein expression during development, and find that the grasshopper hunchback orthologs appear to have a conserved role in early axial patterning of the germ anlagen and in the specification of gnathal and thoracic primordia. In addition, distinct stepped expression levels of hunchback in the gnathal/thoracic domains suggest that grasshopper hunchback may act in a concentration-dependent fashion (as in Drosophila), although morphogenetic activity is not set up by diffusion to form a smooth gradient. Axial patterning functions appear to be performed entirely by zygotic hunchback, a fundamental difference from Drosophila in which maternal and zygotic hunchback play redundant roles. In grasshoppers, maternal hunchback activity is provided uniformly to the embryo as protein and, we suggest, serves a distinct role in distinguishing embryonic from extra-embryonic cells along the anteroposterior axis from the outset of development - a distinction made in Drosophila along the dorsoventral axis later in development. Later hunchback expression in the abdominal segments is conserved, as are patterns in the nervous system, and in both Drosophila and grasshopper, hunchback is expressed in a subset of extra-embryonic cells. Thus, while the expected domains of hunchback expression are conserved in Schistocerca, we have found surprising and fundamental differences in axial patterning, and have identified a previously unreported domain of expression in Drosophila that suggests conservation of a function in extra-embryonic patterning.