概括
DNA限制内核酶EcoRI裂变揭示了核细胞的可访问性. 只有33%的牛卫星IDNA在完整的细胞核中被分裂,这表明在染色质结构中具有显著的位置可访问性.
科学领域:
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
- 生物化学 生物化学
背景情况:
- 牛卫星I DNA是基因组内的重复序列.
- 限制内核酶EcoRI在特定的识别位点分裂DNA.
- 核体是DNA包装的基本结构单元.
研究的目的:
- 为了分析核细胞内特定核酸序列的可访问性,以DNA限制内核酶.
- 为了研究EcoRI在牛卫星I DNA中的裂解效率,在完整核中的核体阵列内.
- 开发一种方法来分离特定的DNA序列作为染色体.
主要方法:
- 牛基因组DNA的切割与限制性内核酶EcoRI.
- 使用凝电泳分析分析DNA片段.
- 糖梯度速度离心,用于染色体隔离.
- 核酶消化来分析染色质结构.
主要成果:
- 几乎所有的裸体卫星IDNA都被EcoRI切割成1400bp的碎片.
- 只有33%的卫星IDNA以1400bp的碎片从完整的核中释放出来.
- 核中的57%的EcoRI位点可以进行裂变,其中一些发生在核细胞核内.
- 隔离了70%的卫星I染色体的纯部分,保留了核细胞亚单元结构.
结论:
- 核体组织限制了牛卫星I DNA中的EcoRI裂的可访问性.
- 很大一部分EcoRI网站仍然可以在完整的核心中访问.
- 特定的DNA序列可以被分离为染色质,而不会破坏它们的结构.
相关概念视频
Nucleotide Excision Repair
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Fixing Double-strand Breaks
The double-stranded structure of DNA has two major advantages. First, it serves as a safe repository of genetic information where one strand serves as the back-up in case the other strand is damaged. Second, the double-helical structure can be wrapped around proteins called histones to form nucleosomes, which can then be tightly wound to form chromosomes. This way, DNA chains up to 2 inches long can be contained within microscopic structures in a cell. A double-stranded break not only damages...
DNA Damage can Stall the Cell Cycle
In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
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DNA Distortion and Damage
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
DNA Damage Can Stall the Cell Cycle
In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...


