果虫的剂量补偿系统是由新进化的X染色体合作选择的
I Marín1, A Franke, G J Bashaw
1Department of Biological Sciences, Stanford University, California 94305, USA.
Nature
|September 12, 1996
概括
在Drosophila中,剂量补偿通过与X染色体结合的男性特异性致死性 (MSL) 蛋白来实现. 这项研究揭示了多类物种中保存的MSL结合,与性染色体进化和X-自体转位相关.
科学领域:
- 遗传学 遗传学 是一个
- 进化生物学 进化生物学
- 分子生物学分子生物学
背景情况:
- 剂量补偿使不同性染色体数量的物种的性别相关基因表达相等.
- 在Drosophila melanogaster中,雄性特异性致死性 (MSL) 蛋白通过结合雄性X染色体来调节剂量补偿.
研究的目的:
- 为了研究MSL蛋白结合在多类物种的进化保存.
- 确定MSL结合模式是否与性染色体进化相关,特别是X-自体转位.
主要方法:
- 在四个类型的类动物中对MSL蛋白质结合的比较分析.
- 检查新进化X染色体臂由于转位而导致的物种中MSL结合模式.
主要成果:
- 三种MSL蛋白的性别和染色体特异性结合在多种多类动物中保持着.
- MSL结合发生在新获得的X染色体臂上,由X-自体转位引起,特别是在同源退化后.
- 在Drosophila miranda中,新X染色体上的MSL结合模式与已知的剂量补偿区域保持一致.
结论:
- MSL介导的剂量补偿是Drosophila属的一种保存机制.
- MSL结合是剂量补偿的可靠指标,并与性别染色体重组协同演变.
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.
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...
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.
02:32Exon 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...