Center for Biospectroscopy and School of Chemistry, Monash Immunology and Stem Cell Laboratories, Monash University, Clayton, Victoria, 3800 Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia.
Nucleic Acids Res. 2011 Jul;39(13):5439-48. doi: 10.1093/nar/gkr175. Epub 2011 Mar 29.
The ability to detect DNA conformation in eukaryotic cells is of paramount importance in understanding how some cells retain functionality in response to environmental stress. It is anticipated that the B to A transition might play a role in resistance to DNA damage such as heat, desiccation and toxic damage. To this end, conformational detail about the molecular structure of DNA has been derived primarily from in vitro experiments on extracted or synthetic DNA. Here, we report that a B- to A-like DNA conformational change can occur in the nuclei of intact cells in response to dehydration. This transition is reversible upon rehydration in air-dried cells. By systematically monitoring the dehydration and rehydration of single and double-stranded DNA, RNA, extracted nuclei and three types of eukaryotic cells including chicken erythrocytes, mammalian lymphocytes and cancerous rodent fibroblasts using Fourier transform infrared (FTIR) spectroscopy, we unequivocally assign the important DNA conformation marker bands within these cells. We also demonstrate that by applying FTIR spectroscopy to hydrated samples, the DNA bands become sharper and more intense. This is anticipated to provide a methodology enabling differentiation of cancerous from non-cancerous cells based on the increased DNA content inherent to dysplastic and neoplastic tissue.
在真核细胞中检测 DNA 构象的能力对于理解某些细胞如何在应对环境压力时保持功能至关重要。预计 B 型到 A 型的转变可能在抵抗 DNA 损伤方面发挥作用，例如热、干燥和毒性损伤。为此，DNA 分子结构的构象细节主要源自提取或合成 DNA 的体外实验。在这里，我们报告说，在脱水的情况下，完整细胞的细胞核中可能会发生类似于 B 型到 A 型的 DNA 构象变化。在空气干燥细胞中重新水合时，这种转变是可逆的。通过使用傅里叶变换红外（FTIR）光谱系统地监测单链和双链 DNA、RNA、提取的核以及包括鸡红细胞、哺乳动物淋巴细胞和癌性啮齿动物成纤维细胞在内的三种真核细胞的脱水和再水合，我们明确地在这些细胞内分配了重要的 DNA 构象标记带。我们还证明，通过将 FTIR 光谱应用于水合样品，DNA 带变得更尖锐和更强烈。预计这将提供一种基于发育不良和肿瘤组织固有的增加的 DNA 含量来区分癌性和非癌性细胞的方法。
