德洛索菲拉雄性生殖系干细胞的不对称分裂显示了非对称的组织蛋白分布
Vuong Tran1, Cindy Lim, Jing Xie
1Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA.
Science (New York, N.Y.)
|November 3, 2012
概括
干细胞在分裂过程中不对称地将老基因组分离给自己,保留表观遗传信息. 这种机制确保干细胞的身份得到维护,与原始细胞不同.
科学领域:
- 细胞生物学 细胞生物学
- 表观遗传学 在表观遗传学中,表观遗传学是指表观遗传学.
- 发育生物学 发展生物学
背景情况:
- 干细胞具有独特的自我更新和分化的能力.
- 在不对称的细胞分裂过程中表观遗传信息的继承仍然不太了解.
- 基因组蛋白在包装和调节DNA中起着至关重要的作用,影响基因表达和细胞身份.
研究的目的:
- 为了调查干细胞是否通过细胞分裂期间的不对称的组织蛋白分离来保持表观遗传信息.
- 在这个过程中确定不同类型的组素 (正规的H3与变体H3.3) 在这个过程中的作用.
- 探索基因组分布对干细胞身份和功能的影响.
主要方法:
- 采用双色标记技术,在Drosophila雄性生殖系干细胞 (GSCs) 中区分"旧"和"新"基因素.
- 在不对称地分裂的GSC和对称地分裂的原始细胞中分析了组蛋白分布模式.
- 采用基因操纵来改变GSC的分裂模式,并观察对基因组分离的影响.
主要成果:
- 在不对称分裂过程中向干细胞展示了先前存在的正规H3基因素的选择性分离.
- 表明新合成的基因组质被优先纳入分化子细胞.
- 观察到这种不对称的基因组分布是GSCs特有的,并且在对称的分裂时会消失.
- 发现变异性H3.3基因组没有与正规的H3.3基因组相同的选择性分离模式.
结论:
- 干细胞在不对称的细胞分裂过程中积极保留先前存在的正规组织蛋白.
- 这种不对称的组素分布是维持干细胞特异性表观遗传状态和分子性质的关键机制.
- 这些发现为管理干细胞身份和自我更新的基本过程提供了洞察力.
相关概念视频
02:45The Ratio of X Chromosome to Autosomes
In most organisms, sex is determined by the ratio of X and Y chromosomes. However, in some organisms, such as Drosophila and C.elegans, sex is determined by the ratio of the number of X chromosomes to the number of sets of autosomes. The Y chromosome in Drosophila is active but does not determine sex. It contains genes responsible for the production of sperms in adult flies.
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
03:17Inheritance of Chromatin Structures
Epigenetics is the study of inherited changes in a cell's phenotype without changing the DNA sequences. It provides a form of memory for the differential gene expression pattern to maintain cell lineage, position-effect variegation, dosage compensation, and maintenance of chromatin structures such as telomeres and centromeres. For example, the structure and location of the centromere on chromosomes are epigenetically inherited. Its functionality is not dictated or ensured by the underlying DNA...
02:04Polytene Chromosomes
Polytene chromosomes are giant interphase chromosomes with several DNA strands placed side by side. They were discovered in the year 1881 by Balbiani in salivary glands, intestine, muscles, malpighian tubules, and hypoderm of larvae Chironomus plumosus. Hence, these are also called "Salivary gland chromosomes." These are found in insects of the order Diptera and Collembola; in certain organs of mammals; and synergids, antipodes of flowering plants. Polytene chromosomes are also regularly...
02:32Position-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.
02:50Dosage Compensation
In animals, gender is determined by the number and type of sex chromosome. For example, human females have two X chromosomes, and males have one X and one Y chromosome, whereas C.elegans with one X chromosome is a male, and the one with two X chromosomes is a hermaphrodite.
In addition to sexual development, the X chromosome has genes involved in autosomal functions such as brain development and the immune system. Therefore, males and females with distinct numbers of X chromosomes will have...
In addition to sexual development, the X chromosome has genes involved in autosomal functions such as brain development and the immune system. Therefore, males and females with distinct numbers of X chromosomes will have...
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.
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...