概括
与Xenopus borealis相比,Xenopus laevis的核糖体基因在杂交胚胎中占主导地位,因为它具有更多的增强元件和更好的促进功能. 这就解释了这些物种中核的优势.
科学领域:
- 发育生物学 发展生物学
- 遗传学 是一个遗传学.
背景情况:
- 核细胞主导是一种现象,在杂交动物中只有一组核细胞基因被表达.
- 了解核细胞优势的遗传和分子基础对于发育研究至关重要.
研究的目的:
- 调查Xenopus laevis和Xenopus borealis之间核主导的机制.
- 在杂交胚胎中识别 X. laevis 核糖体基因优先表达的因素.
主要方法:
- 从X. laevis和X. borealis中克隆的核糖体基因微注射到两种物种的卵子和胚胎中.
- 在混合系统中分析基因表达和促进体活性.
主要成果:
- 在杂交胚胎中,X. laevis的核糖体基因表现出主导地位.
- 比起X. borealis间距器,X. laevis间距器含有更多的强化剂元素用于核糖体基因促进器.
- 该X. laevis促进剂与两种物种的转录机械有效地运作,而X. borealis促进剂与X. laevis转录机械的相互作用很差.
结论:
- X. laevis 核糖体基因的优势主要归因于其间隔区域中更多的增强元件.
- 不同的促进器机械相互作用也导致核细胞主导,有利于X. laevis.
相关概念视频
01:58X-Inactivation
The human X chromosome contains over ten times the number of genes as in the Y chromosome. Since males have only one X chromosome, and females have two, one might expect females to produce twice as many of the proteins, with undesirable results.
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.
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...
01:43Incomplete Dominance
Gregor Mendel's work (1822 - 1884) was primarily focused on pea plants. Through his initial experiments, he determined that every gene in a diploid cell has two variants called alleles inherited from each parent. He suggested that amongst these two alleles, one allele is dominant in character and the other recessive. The combination of alleles determines the phenotype of a gene in an organism.
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...
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...