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首页> 外文期刊>Protoplasma: An International Journal of Cell Biology >The intergenic spacer region of the rDNA in Haplopappus gracilis (Nutt.) Gray
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The intergenic spacer region of the rDNA in Haplopappus gracilis (Nutt.) Gray

机译:细齿瓢虫rDNA的基因间隔区(灰色)

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摘要

In this paper, we provide further information on the genome organisation of Haplopappus gracilis, one of the six angiosperms showing the lowest chromosome number, i.e. 2n = 4, by determining the nucleotide sequence of the intergenic spacer region of the ribosomal RNA genes and its cytological localization on metaphase chromosomes. DNA sequence analysis reveals the occurring of a product of 4,382 bp in length, characterised by the presence of four blocks of different repeated sequences. Our analysis also evidenced putative promoter regions with three transcription initiation sites for polymerase I, as previously reported in Artemisia absinthium, belonging to the same Asteraceae family. A fluorescent in situ hybridization with the intergenic spacer probe indicates the presence of rDNA genes only in the satellited chromosomes of H. gracilis; besides, differences in the signal intensity between homologous chromosomes were frequently observed, thus suggesting for these chromosome sites the presence of a variable number of rDNA gene copies, even if a divergent chromatin organisation in corresponding regions cannot be ruled out.
机译:在本文中,我们通过确定核糖体RNA基因的基因间隔区的核苷酸序列及其细胞学信息,提供了关于Haplopappus gracilis(显示最低染色体数,即2n = 4)的六个被子植物之一的基因组结构的进一步信息。定位在中期染色体上。 DNA序列分析揭示了长度为4,382 bp的产物的出现,其特征是存在四个不同重复序列的嵌段。我们的分析还证明了推定的启动子区域,该区域具有三个聚合酶I的转录起始位点,如先前在苦艾蒿中报道的,属于同一菊科家族。与基因间隔子探针的荧光原位杂交表明rDNA基因仅存在于纤毛线虫的卫星染色体中。此外,经常观察到同源染色体之间信号强度的差异,因此,即使不能排除在相应区域中不同的染色质组织,也暗示了这些染色体位点存在可变数量的rDNA基因拷贝。

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