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姉妹染色体のペアリングは,親子遺伝性のヘテロジゴス性を維持する
Aracely A Lutes1, William B Neaves, Diana P Baumann
1Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.
Nature
|February 23, 2010
まとめ
パルテノジェネティックなホイップテールトカゲは, 交配期中の姉妹染色体ペアリングを通じて異異性体を維持する. このユニークなメカニズムは,彼らの繁殖の成功に不可欠な根本的なメオティックプログラムを変えることなく,二倍卵の産卵を可能にします.
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
- 生殖生物学 生殖生物学
背景:
- 鞭尾 (Aspidoscelis) に共通するパートノゲネティック繁殖は,すべて雌の集団を生成します.
- これらのパルテノジェネティック種は,高いヘテロジゴシティを示し,性的な祖先からのハイブリッドの起源を示唆しています.
- 双胞胎卵の産生を可能にするメオティックプロセスが,ヘテロジゴス性を保ちながら不明のままである.
研究 の 目的:
- ヘテロジゴス性の維持に責任を持つパートノゲネティックなウイプテイルカワウソにおけるメオティックメカニズムを解明する.
- 遺伝的多様性を損なうことなく二倍性ゲメットの生成方法を理解する.
主な方法:
- パルテノゲネティックと性的なアスピドセリス種のミオティック染色体数の比較分析.
- シナプトネマル複合体とキアスマの観察により,中性進行を評価する.
- ホモログの染色体を区別するために探査機を用いた光インシット混合化 (FISH).
主要な成果:
- パルテノジェネティックなウイプテールトカゲは,性種と比較して染色体数が2倍でメオシスを開始します.
- メオシスは典型的なシナプトネマル複合体の形成とキアスマで進行し,再結合が起こることを示します.
- 同性染色体は,同性染色体ではなく,姉妹染色体間で形成され,異性染色体を保持します.
結論:
- 姉妹染色体のペアリングは,パートノゲネティックなアスピドセリスの異性交性を維持するための重要なメカニズムです.
- このプロセスは,改変されたメオティックプログラムを介して,還元されていない二倍性卵の産生を可能にします.
- ヘテロジゴシティの維持は,無性生殖と遺伝的多様性の制限による身体的不具合を相殺するために不可欠です.
関連する概念動画
Chromosomal Theory of Inheritance
In 1866, Gregor Mendel published the results of his pea plant breeding experiments, providing evidence for predictable patterns in the inheritance of physical characteristics. The significance of his findings was not immediately recognized. In fact, the existence of genes was unknown at the time. Mendel referred to hereditary units as “factors.”
Crossing Over
Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where each chromosome—replicated in S phase—is now composed of two sister chromatids (identical copies) joined centrally.
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
Crossing Over
Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I, duplicated...
Lampbrush Chromosomes
In 1882, Flemming observed lampbrush chromosomes (LBC) in salamander eggs. Later in 1892, Rückert observed LBCs in shark egg cells and coined the term "lampbrush chromosomes" because they looked like brushes used to clean kerosene lamps.
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops resemble the...
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops resemble the...
Lampbrush Chromosomes
In 1882, Flemming observed lampbrush chromosomes (LBC) in salamander eggs. Later in 1892, Rückert observed LBCs in shark egg cells and coined the term "lampbrush chromosomes" because they looked like brushes used to clean kerosene lamps.
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops resemble the...
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops resemble the...
Nondisjunction
During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed sister chromatid separation during meiosis II. In some species, notably plants, nondisjunction can result in an organism with an entire additional set of chromosomes, which is called polyploidy. In humans, nondisjunction can occur during male or female gametogenesis and the resulting gametes possess one too many or one too few chromosomes.

