Lukowitz W, Schröder C, Glaser G, Hülskamp M, Tautz D
Institut für Genetik und Mikrobiologie, Universität München, Germany.
Mech Dev. 1994 Feb;45(2):105-15. doi: 10.1016/0925-4773(94)90024-8.
The segmentation gene hunchback (hb) is involved in setting up the anterior-posterior axis of the Drosophila embryo. It is expressed maternally and zygotically and it plays a key role in integrating the effects of the anterior and posterior maternal systems. The hb gene from D. virilis has previously been cloned and was shown to be well conserved in its coding region, but less so in its upstream region which shows a more patchy pattern of conserved and diverged sequences. This work deals with the functional conservation of hb between the two species. We have mapped two additional regulatory elements for the expression of hb in the early embryo, namely the enhancer for the maternal expression and the enhancer region for the late blastoderm expression. Fragments containing these two elements, the previously identified bicoid dependent element for the early blastoderm expression of hb and the coding region were taken from D. virilis and tested in the D. melanogaster background. We find that all enhancer elements as well as the coding region are functionally conserved between the two species. Comparison of the upstream sequences that include the enhancer region for the late blastoderm expression reveal seven highly conserved blocks. Some of these contain consensus binding sites for transregulatory factors that are likely to control the respective expression domains.
分节基因驼背（hb）参与果蝇胚胎前后轴的建立。它在母体和合子中都有表达，并且在整合前后母体系统的效应方面起着关键作用。之前已经克隆了来自粗壮果蝇的hb基因，并且其编码区显示出高度保守，但上游区域的保守性较差，该区域呈现出保守和分化序列更为零散的模式。这项工作研究了这两个物种之间hb基因的功能保守性。我们已经定位了另外两个在早期胚胎中调控hb基因表达的元件，即母体表达增强子和胚盘后期表达增强子区域。包含这两个元件、之前鉴定出的用于hb基因早期胚盘表达的双尾依赖元件以及编码区的片段取自粗壮果蝇，并在黑腹果蝇背景下进行了测试。我们发现所有增强子元件以及编码区在这两个物种之间功能上是保守的。对包括胚盘后期表达增强子区域在内的上游序列进行比较，发现了七个高度保守的区域。其中一些区域包含可能控制各自表达结构域的反式调节因子的共有结合位点。
