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Manipulation of Ploidy in Caenorhabditis elegans
Published on: March 15, 2018
交叉不变性是由中性DNA断裂修复的合作伙伴选择决定的
Randy W Hyppa1, Gerald R Smith
1Fred Hutchinson Cancer Research Center, Division of Basic Sciences, Seattle, WA 98109, USA.
Cell
|July 27, 2010
概括
裂变酵母通过改变DNA断裂的修复方式来维持每个DNA长度的一致的交叉频率. 这种机制有利于在低分解区域的同类染色体之间的修复,不同于芽酵母,可以广泛应用于不同物种.
科学领域:
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
- 细胞生物学 细胞生物学
背景情况:
- 介质交叉对于介质过程中精确的染色体分离至关重要.
- 交叉点的数量和位置受到严格监管,这一过程被称为交叉点平衡.
- 在芽酵母中,交叉稳态通过在DNA双链断裂 (DSB) 频率下降时偏好交叉对非交叉的水平来维持交叉水平.
研究的目的:
- 为了研究裂变酵母中交叉控制的机制,特别是每千基基 (kb) 的DNA交叉频率的近不变性.
- 了解裂变酵母如何保持恒定的交叉水平,尽管在整个基因组的DSB强度的变化.
主要方法:
- 基因分析以评估交叉频率和DSB修复结果.
- 物理测绘技术,以确定DSB和交叉车的位置和频率.
- 在基因组内对DSB丰富的热点和DSB贫困区域进行比较分析.
主要成果:
- 裂变酵母表现出几乎不变的交叉频率每kb的DNA,无论当地的DSB强度.
- 裂变酵母中的交叉控制依赖于在DSB的姐妹染色体和同质染色体修复之间做出选择.
- 在DSB冷区域中,修复主要发生在同类染色体之间,与强烈的DSB热点形成对比,在那里姐妹染色体修复占主导地位 (约. 他们的比例是3:1).
结论:
- 姐妹染色体和同类体之间的差异修复选择是保持裂变酵母交叉不变性的关键机制.
- 这种机制为许多物种中观察到的DSBs超过交叉的过量提供了新的解释.
- 这些发现表明,这种交叉控制策略可能在各种真核生物体中得到保护,这可能解释了未配对染色体上的DSB修复.
相关概念视频
01:34Crossing Over
Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where each chromosome—replicated in S phase—is now composed of two sister chromatids (identical copies) joined centrally.
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
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02:02Meiosis II
Meiosis II entails cell division and segregation of the sister chromatids, resulting in the production of four unique haploid gametes. The steps for meiosis II are similar to mitosis, except that meiosis II occurs in haploid cells, whereas mitosis occurs in diploid cells.
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02:57Meiosis vs. Mitosis
Cell division is necessary for growth and reproduction in organisms. Mitosis aids cell growth and development by dividing somatic cells. In contrast, meiosis causes the division of germ cells and plays an essential role in sexual reproduction. Due to their unique functional requirements, mitosis and meiosis differ from each other in multiple aspects.
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Before the start of mitosis and meiosis I, the cell synthesizes DNA, resulting in two homologous copies of each chromosome. DNA synthesis is...
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Other than maintaining genome stability via DNA repair, homologous recombination plays an important role in diversifying the genome. In fact, the recombination of sequences forms the molecular basis of genomic evolution. Random and non-random permutations of genomic sequences create a library of new amalgamated sequences. These newly formed genomes can determine the fitness and survival of cells. In bacteria, homologous and non-homologous types of recombination lead to the evolution of new...
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Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I, duplicated...