发布: 2017年06月05日第7卷第11期 DOI: 10.21769/BioProtoc.2305 浏览次数: 13404
评审: Emilie BesnardAnonymous reviewer(s)
Abstract
The DNA combing method allows the analysis of DNA replication at the level of individual DNA molecules stretched along silane-coated glass coverslips. Before DNA extraction, ongoing DNA synthesis is labeled with halogenated analogues of thymidine. Replication tracks are visualized by immunofluorescence using specific antibodies. Unlike biochemical and NGS-based methods, DNA combing provides unique information on cell-to-cell variations in DNA replication profiles, including initiation and elongation. Finally, this assay can be used to monitor the effect of DNA lesions on fork progression, arrest and restart.
Keywords: Replication (复制)Background
DNA synthesis is initiated at thousands of sites on eukaryotic chromosomes called replication origins. Origin activation follows a well-defined replication timing program that is controlled by checkpoint kinases and epigenetic modifications of chromatin (Prioleau and MacAlpine, 2016). Replication forks frequently stall during a normal S phase. Fork arrest is caused by multiple events, such as DNA lesions, tightly bound protein complexes, and transcription at highly expressed genes (Tourriere and Pasero 2007; Zeman and Cimprich, 2013). Eukaryotes have developed different strategies to deal with this replication stress, including repair mechanisms to restart arrested forks and activation of dormant replication origins to rescue terminally-arrested forks.
DNA combing is a method of choice to monitor different aspects of replication (fork speed, origin usage, fork restart, sister fork asymmetry). Unlike other DNA fiber methods such as DNA fiber spreading, the stretching, density and alignment of DNA molecules are highly reproducible and tightly controlled in the DNA combing method. Stretching is imposed by the force exerted by a receding air/water interface, independently of the length of DNA fibers (Bensimon et al., 1994; Michalet et al., 1997). Origin firing and progression of replication forks are followed after incorporation of thymidine analogs, such as 5-bromo-2’-deoxyuridine (BrdU), 5-iodo-2’-deoxyuridine (IdU) and 5-chloro-2’-deoxyuridine (CldU) in newly-synthesized DNA. This technique has been successfully used to monitor DNA replication dynamics in a variety of organisms, including bacteria, yeast, Drosophila, Xenopus and mammals.
Here, we provide detailed protocols to analyze newly synthesized DNA fibers in budding yeast and in human cells and to investigate various aspects of DNA replication in normal growth conditions and under replicative stress.
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版权信息
© 2017 The Authors; exclusive licensee Bio-protocol LLC.
如何引用
Tourrière, H., Saksouk, J., Lengronne, A. and Pasero, P. (2017). Single-molecule Analysis of DNA Replication Dynamics in Budding Yeast and Human Cells by DNA Combing. Bio-protocol 7(11): e2305. DOI: 10.21769/BioProtoc.2305.
分类
癌症生物学 > 通用技术 > 生物化学试验
生物化学 > DNA > 单分子活性
分子生物学 > DNA > DNA 标记
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