在Drosophila中发生的基因突变与产生piRNA的基因突变有关
Augustin de Vanssay1, Anne-Laure Bougé, Antoine Boivin
1Laboratoire Biologie du Développement, UMR7622, CNRS-Université Pierre et Marie Curie, 9 quai Saint Bernard, 75005 Paris, France.
Nature
|August 28, 2012
概括
在动物中,基因表观突变会在几代之间使转基因沉默. 这一由piRNAs调解的过程将非沉声转基因转化为强大的表观遗传沉声器,建立新的piRNA loci.
科学领域:
- 表观遗传学 在表观遗传学中,表观遗传学是指表观遗传学.
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
背景情况:
- 参突变涉及无需改变DNA序列的等位基因的遗传表观遗传修饰.
- 过静音效应 (TSE) 是P-可转换元素的同质性依赖的静音机制.
- 参突变可以导致长期传输的表观遗传状态,跨越几代人.
研究的目的:
- 描述一种具有长期代代传播的动物中新型变异病例.
- 调查Piwi相互作用RNAs (piRNAs) 在调解类突变中的作用.
- 为piRNA位点和跨代抑制的出现建立一个遗传模型.
主要方法:
- 研究了能够诱导TSE的P元素衍生型转基因集群.
- 研究了非TSE转基因集群的转化为强大的沉声器.
- 分析了含有piRNAs的细胞质母性遗传的作用.
- 检查了茄子和Dicer-2突变对偏变的影响.
主要成果:
- 诱导强TSE的P元素转基因集群将同类非TSE集群转化为50代的强沉声器.
- 偏变发生在没有染色体配对的情况下,并且由母体的piRNAs介导.
- 功能丧失的茄子突变取消了镇压,而Dicer-2突变没有.
- 转基因变异的位点变得稳定,强大的piRNA生产者,并且它们本身也是类转基因的.
结论:
- 这项研究提出了一种由piRNAs介导的动物对基因变异的遗传模型.
- 这些发现表明可转移元素的RNA介导的跨代镇压.
- 参突变可以导致功能piRNA位点的新出现.
相关概念视频
piRNA - Piwi-interacting RNAs
PIWI-interacting RNAs, or piRNAs, are the most abundant short non-coding RNAs. More than 20,000 genes have been found in humans that code for piRNAs while only 2000 genes have been found for miRNAs. piRNAs can act at the transcriptional and post-transcriptional levels and have a vital role in silencing transposable elements present in germ cells. They are also involved in epigenetic silencing and activation. Previously, they were thought to function only in germ cells but new evidence suggests...
Position-effect Variegation
In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.
Gene Duplication and Divergence
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.
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.
Bacterial RNA Polymerase
Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
Cis-regulatory Sequences
Cis-regulatory sequences are short fragments of non-coding DNA that are present on the same chromosomes as the genes that they regulate. These fragments serve as binding sites for transcriptional regulators, proteins that are responsible for controlling gene transcription and differential gene expression across cell types in eukaryotes. Cis-regulatory sequences can be close to the gene of interest or thousands of bases away in the DNA sequence; however, those sequences that are further away are...
Exon Recombination
The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes.
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Exon shuffling follows “splice frame rules.” Each exon has three reading...


