概括
海中的重复性DNA序列显示了物种之间频率和序列的显著变化. 这些发现突显了密切相关的海之间基因组结构的进化分歧.
科学领域:
- 分子生物学分子生物学
- 进化生物学 进化生物学
- 基因组学就是基因组学.
背景情况:
- 重复的DNA序列在真核基因组中很丰富,并在基因组进化中发挥作用.
- 了解重复序列的动态对于破译物种之间的进化关系至关重要.
研究的目的:
- 为了估计在三种海鱼物种的DNA中出现重复序列家族的频率: *Strongylocentrotus purpuratus*, *Strongylocentrotus franciscanus* 和 *Lytechinus pictus*.
- 研究这些密切相关物种中重复性DNA序列及其频率的进化变化.
主要方法:
- 通过重新关联,S1核酶消化,并将其插入等离子体RSF2124.4中,克隆*S. purpuratus*重复序列元素.
- 动力和和再关联实验,以估计不同海刺物种DNA中的重复频率.
- 测量重新关联的DNA片段的热稳定性,以评估序列分离.
主要成果:
- 在*S. franciscanus*DNA中, *S. purpuratus*重复序列的重复频率比*S. purpuratus*DNA低约1到20倍.
- 在*L. pictus*DNA中检测到的这些序列的副本很少.
- 一种物种的重复性DNA序列通常与其他物种的DNA更慢地重新关联,这表明相关物种的频率较低.
- 大多数重复性家族在频率和序列上都表现出变化,其中一些表现出显著的频率转移,但序列的变化最小.
结论:
- 主导的重复序列家族在密切相关的海鱼物种中没有保持频率.
- 进化过程导致了这些物种中重复性DNA元素的丰富性和序列的实质性变化.
- 对重复性DNA的比较分析提供了对海基因组的进化分歧的见解.
相关概念视频
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In contrast, regions which code...
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The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of the genes in bacteria, archaebacteria, and eukaryotes was generated by gene duplication and divergence, indicating its critical role in evolution.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
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Maxam-Gilbert Sequencing
In the same year as the discovery of the Sanger sequencing method, another group of scientists, Allan Maxam and Walter Gilbert, demonstrated their chemical-cleavage method for DNA sequencing. The Maxam-Gilbert method relies on using different chemicals that can cleave the DNA sequence at specific sites, the separation of resulting DNA fragments of variable size using electrophoresis, and deciphering the DNA sequence from the resulting gel bands.
Challenges of the Maxam-Gilbert Method
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Challenges of the Maxam-Gilbert Method
The...
Gene Evolution - Fast or Slow?
The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain crucial regulatory sequences, the vast majority of this DNA serves no known function. Typically, these regions of the genome are the ones in which the fastest change, in evolutionary terms, is observed, because there is typically little to no selection pressure acting on these regions to preserve their sequences.
In contrast, regions which code...
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Genetic Variation
Genetic variation is the diversity in DNA sequences found among individuals of the same species. This diversity is crucial for a species' survival because it helps organisms adapt to environmental changes. Genetic variation begins with fertilization, where an egg and sperm cell merge. Each of these cells carries 23 chromosomes, up to 46 in the fertilized egg. Chromosomes are long DNA strands that contain genes, the basic units of heredity.
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Genes exist in different versions called alleles, which...


