Physiological role of fused mRNA of two homeotic genes in crustaceans

为了阐明甲壳类中Hox融合基因的生理功能，本研究对大型蚤（Daphnia magna）中的Ubx/Antp融合基因进行了详细的分析，并获得了以下研究结果.在热休克启动子和肌动蛋白启动子的调控下，构建了各种缺陷型或突变型的大型果蝇Ubx/Antp，但这些突变型或缺陷型的构建体无法克服mRNA不稳定的问题. D.对包括Dfd、Hox 3、pb和lab区在内的magna Hox基因簇进行了全序列测定。此外，在D. pulex的基因组序列与D.大基因组和cDNA序列。在水蚤Hox集群中，两个microRNA产生位点，在昆虫基因组中高度保守，也是保守的。在D.电影UBX-和Antp。这些发现沿着上述观察，即Ubx/Antp融合转录本非常不稳定，提示这些microRNA的功能可能介导了融合转录本对HOM蛋白的翻译调控. RNA干扰技术在D.发育出麦格纳胚，并在相应的基因表达区域证实了一些RNA介导的形态缺陷。

To address the physiological roles of the fusion Hox transcripts observed in crustaceans, fused Ubx/Antp transcript in Daphnia magna was analyzed in detail, and the following results were obtained from this research.1. Various deficient or mutant versions of D.magna Ubx/Antp were constructed and expressed under the control of the heat shock promoter and the actin promoter, however, it was impossible to overcome the problem of mRNAs instabilities from these mutant/deficient constructs, unfortunately.2. A part of D. magna Hox cluster including Dfd, Hox3, pb, and lab regions was sequenced completely. Also the Hox cluster region in D. pulex, sequenced by an international research organization, Daphnia Genome Consortium, was annotated by comparison with D. magna genomic and cDNA sequences. In Daphnia Hox clusters, two microRNA producing loci, highly conserved among insect genomes, were also conserved. Putative target sequences for these microRNAs were found in 3'-UTR of D. movie Ubx- and Antp. These findings along with above-mentioned observation that fused Ubx/Antp transcripts were, extremely unstable suggested that translational control of HOM proteins from fused transcripts might be mediated by the functions of these microRNAs.3. RNA interference method in D. magna embryos was developed and some &RNA-mediated morphological defects were confirmed in the corresponding regions with gene expression domains.