Physiological role of fused mRNA of two homeotic genes in crustaceans

为了解决甲壳类动物中观察到的融合Hox转录本的生理作用，我们对大水蚤中融合Ubx/Antp转录本进行了详细的分析，得到了以下结果：1。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D.magna Ubx/Antp的各种缺陷或突变版本，但不幸的是，无法克服这些突变/缺陷构建的mrna不稳定性问题。对D. magna Hox簇的Dfd、Hox3、pb和lab区域进行了完整的测序。国际研究组织Daphnia Genome Consortium对D. pulex的Hox簇区进行了测序，并与D. magna基因组和cDNA序列进行了比对。在水蚤群中，两个microRNA产生位点在昆虫基因组中高度保守。在D. movie Ubx-和Antp的3'- utr中发现了这些microrna的推测靶标序列。这些发现以及上述关于融合的Ubx/Antp转录本非常不稳定的观察表明，融合转录本对HOM蛋白的翻译控制可能是由这些micrornas的功能介导的。采用RNA干扰法对大鼠胚胎进行检测，在基因表达域的相应区域发现了一些由RNA介导的形态学缺陷。

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.