Physiological role of fused mRNA of two homeotic genes in crustaceans

为了研究在甲壳类动物中观察到的融合HOX转录本的生理作用，本研究对大型水蚤UBX/ANTP融合转录本进行了详细的分析，获得了以下结果。在热休克启动子和肌动蛋白启动子的控制下，构建和表达了各种缺失或突变版本的大盾壳Ubx/ANTP，然而不幸的是，这些突变/缺失的构建体不可能克服mRNAs的不稳定性问题。完成了包括DFD区、Hox3区、PB区和Lab区在内的一部分大型稻瘟病菌的基因序列测定。此外，国际研究组织大型水蚤基因组联合会测定了该种群的Hox簇区，并将其与大型水蚤的基因组和cDNA序列进行了比较。在Daphnia Hox集群中，两个在昆虫基因组中高度保守的microRNA产生位点也是保守的。这些microRNAs的假定靶序列存在于D电影Ubx-和ANTP的3‘-UTR中。这些发现以及上面提到的融合Ubx/ANTP转录本极不稳定的观察表明，融合转录本中Hom蛋白的翻译控制可能是通过这些microRNA的功能来介导的。建立了在大麦胚胎中进行RNA干扰的方法，并在具有基因表达结构域的相应区域中证实了一些由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.