双葉植物におけるX結合遺伝子が,退廃したY結合同型遺伝子を有する
1Department of Ecology and Evolution, University of Chicago, Illinois 60637, USA. dguttman@midway.uchicago.edu
Nature
|June 2, 1998
まとめ
研究者らは,植物における最初のX関連遺伝子と,同類のY関連ロクスを特定し,Silene latifoliaの性染色体進化の初期段階を明らかにした. この発見は,植物性染色体がどのように分岐するかについて光を当てています.
科学分野:
- 進化生物学の進化生物学について
- 遺伝学 遺伝学とは
- 植物学は植物科学である.
背景:
- ほとんどの開花植物はヘルマフロディットであり,男性と女性の生殖器官の両方を備えています.
- 異なる性別を持つ二重種は,植物種の4%未満を占め,しばしば染色体媒介性性別決定を使用します.
- 植物性染色体の最近の独立した進化は,初期の進化段階を研究するためのユニークなモデルを提供します.
研究 の 目的:
- 双葉植物のY染色体上の最初のX結合遺伝子とその同類の位置を識別し,特徴づけること.
- 植物性染色体で発生する変性を含む進化過程を調査する.
- 発芽植物における性染色体進化の初期段階についての洞察を提供するため.
主な方法:
- シレネ・ラティフォリア (Silene latifolia) の二卵性植物における遺伝子解析.
- X染色体に関連した男性特異のタンパク質エンコーディング遺伝子の特定.
- Y染色体上の同類の場所の特徴付け,変性に対する配列解析を含む.
主要な成果:
- 植物における最初のX関連遺伝子が特定され,男性特異のタンパク質をコードした.
- Y染色体には退廃した同類の場所が発見され,その特徴は,ニュクレオチドの切除と重複する配列である.
- 活発なX-リンクされたロカスと退廃したY-リンクされたロカスとの共通の祖先の証拠が確立されました.
結論:
- この研究は,植物における最初の同類性の性関連ロシを特定し,早期の性染色体進化に関する重要な洞察を提供した.
- シレネ・ラティフォリア (Silene latifolia) のY連結ロカス (Y-linked locus) の変異は,性染色体の進化の軌道を例示しています.
- これらの発見は,植物性染色体につながる最近の,複製された進化の出来事の仮説を裏付けている.
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関連する概念動画
X-linked Traits
In most mammalian species, females have two X sex chromosomes and males have an X and Y. As a result, mutations on the X chromosome in females may be masked by the presence of a normal allele on the second X. In contrast, a mutation on the X chromosome in males more often causes observable biological defects, as there is no normal X to compensate. Trait variations arising from mutations on the X chromosome are called “X-linked”.
Incomplete 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.
X and Y Chromosomes
Among mammals, the gender of an organism is determined by the sex chromosomes. Humans have two sex chromosomes, X and Y. Every human diploid cell has 22 pairs of autosomes and one pair of sex chromosomes. A human female has two X chromosomes, while a male has one X chromosome and one Y chromosome.
The germline cells such as egg and sperm cells carry only half the number of chromosomes, i.e., 22 autosomes and one sex chromosome. All eggs have an X chromosome, while sperm cells can carry an X or...
The germline cells such as egg and sperm cells carry only half the number of chromosomes, i.e., 22 autosomes and one sex chromosome. All eggs have an X chromosome, while sperm cells can carry an X or...
The 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...
X-linked Traits
In most mammalian species, females have two X sex chromosomes and males have an X and Y. As a result, mutations on the X chromosome in females may be masked by the presence of a normal allele on the second X. In contrast, a mutation on the X chromosome in males more often causes observable biological defects, as there is no normal X to compensate. Trait variations arising from mutations on the X chromosome are called “X-linked”.
Dosage 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...
