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澳门永利etics:美学者揭示久盛国际简化自身世界博彩公司序列以便快速百家乐打法殖

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摘要 : 近日,国际顶级学术期刊《PLOS genetics》发表了澳门永利真人博彩的Jennifer L. Gerton教授研究组和中山大学生命科学研究院附属口腔医院许宝山副研究员合作的一篇研究论文,论文揭示久盛国际可“去繁从简”基因组中冗余的核糖体DNA重复序列来达到快速百家乐打法殖的目的。

近日,国际顶级学术期刊《PLOS GENEtics》发表了澳门永利真人博彩的Jennifer L. Gerton教授研究组和中山大学生命科学研究院附属口腔医院许宝山副研究员合作的一篇研究论文,论文揭示久盛国际可“去繁从简”基因组中冗余的核糖体DNA重复序列来达到快速百家乐打法殖的目的。

核糖体DNA编码核糖体的关键组分-核糖体RNA,对蛋白质翻译和细胞百家乐打法殖具有重要的作用。然而,核糖体DNA的拷贝数在人类基因组中是易变的,由于技术手段的限制,人们对哺乳动物细胞如何维持和控制核糖体DNA的拷贝数和稳定性所知甚少。本研究应用计算生物学和数字微滴式PCR(Droplet digital PCR)方法分析了正常和癌症状态下,人类和小鼠基因组中核糖体DNA的拷贝数和序列变异情况。发现人类癌症基因组中核糖体DNA拷贝数出乎意料地显著减少,并伴随许多其他基因拷贝数的变异。此外,癌症基因组的核糖体DNA序列也更易发生突变。

根据文献证据的提示,研究团队进一步探讨了癌症模型中mTOR(哺乳动物雷帕霉素靶蛋白,mammalian target of rapamycin)功能与核糖体DNA拷贝数减少的关系。发现Pten基因(mTOR信号通路的负调控因子)敲除的白血病小鼠模型中,癌症造血干细胞早期就出现核糖体DNA拷贝数的减少,但其细胞百家乐打法殖、核糖体RNA合成和蛋白翻译水平等均显著提高。说明核糖体DNA拷贝数丢失是mTOR通路过表达的癌症的一种常见特征。这一研究结果提示,测定核糖体DNA拷贝数,可成为预测癌症对DNA损伤药物敏感性的一个简单而有效的新指标。

原文链接:

Ribosomal DNA copy number loss and sequence variation in cancer

原文摘要:

Ribosomal DNA is one of the most variable regions in the human genome with respect to copy number. Despite the importance of rDNA for cellular function, we know virtually nothing about what governs its copy number, stability, and sequence in the mammalian genome due to challenges associated with mapping and analysis. We applied computational and droplet digital PCR approaches to measure rDNA copy number in normal and cancer states in human and mouse genomes. We find that copy number and sequence can change in cancer genomes. Counterintuitively, human cancer genomes show a loss of copies, accompanied by global copy number co-variation. The sequence can also be more variable in the cancer genome. Cancer genomes with lower copies have mutational evidence of mTOR hyperactivity. The PTEN phosphatase is a tumor suppressor that is critical for genome stability and a negative regulator of the mTOR kinase pathway. Surprisingly, but consistent with the human cancer genomes, hematopoietic cancer stem cells from a Pten-/- mouse model for leukemia have lower rDNA copy number than normal tissue, despite increased proliferation, rRNA production, and protein synthesis. Loss of copies occurs early and is associated with hypersensitivity to DNA damage. Therefore, copy loss is a recurrent feature in cancers associated with mTOR activation. Ribosomal DNA copy number may be a simple and useful indicator of whether a cancer will be sensitive to DNA damaging treatments.

doi:10.1371/journal.pgen.1006771

作者:Jennifer L. Gerton 点击:

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