まとめ
Xenopus laevisのビテロゲニン遺伝子は,コーディング領域では高い同質性を示しているが,イントロンでは著しい差異を示している. 繰り返しDNAとイントロンの再編成は,特定の機能が欠けている可能性を示唆しています.
科学分野:
- 分子生物学は分子生物学である.
- 進化生物学の進化生物学について
- 遺伝学 遺伝学とは
背景:
- ビテロゲニンは,エストロゲンのコントロール下で肝臓で合成され,卵巣では卵黄のタンパク質に加工されます.
- カエルXenopus laevisは,少なくとも4つの異なるビテロゲニン遺伝子を持っています.
研究 の 目的:
- Xenopus laevisのビテロゲニン遺伝子の配列ホモロジーと進化的多様性を調査する.
- これらの遺伝子内のイントロンの構造と潜在的な機能を分析する.
主な方法:
- ヴィテロゲニン遺伝子A1とA2の比較シーケンス分析
- コーディング領域内のイントロンとエクソンの識別と特徴付け.
- 繰り返し発生するDNA要素と,イントロンの内の配列の再編成の分析.
主要な成果:
- ビテロゲニン遺伝子A1とA2は,メッセンジャーRNAのコーディング領域で95%のシーケンスホモロジーを示しています.
- 両方の遺伝子は同類の位置で33個のイントロンを含んでいますが,イントロンの配列と長さは大きく異なります.
- イントロンには繰り返しのDNA要素が含まれており,削除,挿入,複製によって広範な分岐を経験しています.
結論:
- 複製されたビテロゲニン遺伝子のホモログなイントロンは急速に進化した.
- 広範な分岐と重複するDNA含有量は,多くのイントロン配列が特定の機能的役割を持たないかもしれないことを示唆しています.
関連する概念動画
Transgenic Organisms
Overview
Protein Families
Protein families are groups of homologous proteins; that is, they have similarities in amino acid sequences and three-dimensional structures. Protein families usually occur because of gene duplication, where an additional copy of a gene is inserted into the genome of an organism. Mutations that change the amino acids but still allow the protein to be properly synthesized, will lead to new protein family members. If these new proteins contain similar amino acids in key locations, protein...
Cell Specific Gene Expression
Multicellular organisms contain a variety of structurally and functionally distinct cell types, but the DNA in all the cells originated from the same parent cells. The differences in the cells can be attributed to the differential gene expression. Liver cells, whose functions include detoxification of blood, production of bile to metabolize fats, and synthesis of proteins essential for metabolism, must express a specific set of genes to perform their functions. Gene expression also varies with...
Background and Environment Affect Phenotype
Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as temperature, oxygen availability, presence of mutagens, that can alter an organism’s phenotype.
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
Exon 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...
General Transcription Factors
Tissue-specific transcription factors contribute to diverse cellular functions in mammals. For example, the gene for beta globin, a major component of hemoglobin, is present in all cells of the body. However, it is only expressed in red blood cells because the transcription factors that can bind to the promoter sequences of the beta globin gene are only expressed in these cells. Tissue-specific transcription factors also ensure that mutations in these factors may impair only the function of...


