関連する実験動画
Updated: Jul 5, 2026

10:38
Isolation of Early Hematopoietic Stem Cells from Murine Yolk Sac and AGM
Published on: June 27, 2008
最古の血管精子:ミトコンドリア,プラスチド,核ゲノムからの証拠
Y L Qiu1, J Lee, F Bernasconi-Quadroni
1Institute of Systematic Botany, University of Zurich, Switzerland. yqiu@systbot.unizh.ch
Nature
|December 10, 1999
まとめ
咲く植物 (アニオスペルム) の起源が明らかにされ,アンボレラは他のすべての植物に最も初期の血統の姉妹である. この研究は,Anthophyte仮説を否定し,Gnetalesを明らかにしています.
科学分野:
- * 進化生物学について
- * 系統遺伝学について
- * 植物科学について
背景:
- * 芽種は地球全体の植生を支配し,不可欠な資源を提供している.
- * 血管芽類の起源と初期の進化は,依然として重要な科学的な謎である.
- *最も初期のアニオスペルミアとその姉妹群であるジムノスペルミアを特定することは困難です.
研究 の 目的:
- * 初期のアンジオスペルマの系統的位置と,そのジムノスペルマとの関係を解明する.
- * 血管精子の多様化の進化史を調査する.
- * 血管精子の起源に関するアンソフィット仮説を検証する.
主な方法:
- * 5つのミトコンドリア,プラスチド,核遺伝子のDNA配列の系統遺伝分析.
- * ベースアンジオスペルマとジムノスペルマの全ての系統 (105種) を含む.
- * 8,733 塩基対の合計並べられた配列の長さの分析.
主要な成果:
- *アンボレラは,他のすべてのアンジオスペルムの姉妹種として識別され,アンジオスペルムの進化の第一段階を表しています.
- * NymphaealesとIlliciales-Trimeniaceae-Austrobaileyaも,最も初期のアニオスペルム系に含まれています.
- *グネタルは,アニオスペルムの姉妹ではなく,コニファーと関連していることが示され,アンソファイト仮説を否定する.
結論:
- *この研究は,早期の血管精子の進化について,堅実な系統学を提供している.
- *結果は,血管精子内の基礎的関係と体精子群の配置を明確にします.
- * 発見は,血管精子の多様化,適応,ゲノム進化の理解に影響を与えます.
関連する概念動画
Fertilization
During fertilization, an egg and sperm cell fuse to create a new diploid structure. In humans, the process occurs once the egg has been released from the ovary, and travels into the fallopian tubes. The process requires several key steps: 1) sperm present in the genital tract must locate the egg; 2) once there, sperm need to release enzymes to help them burrow through the protective zona pellucida of the egg; and 3) the membranes of a single sperm cell and egg must fuse, with the sperm...
The Evidence for Evolution
Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of novel varieties and entire new species. These changes are responsible for the diverse forms of life inhabiting the planet. The evidence for evolution suggests that all living organisms descended from common ancestors.The collection of fossils within sedimentary rocks give a record of common ancestry and often depicts the history of evolution.
Zygotic Development And Stem Cell Formation
The development of all multicellular organisms starts with the fusion of haploid cells called sperm and egg to form a diploid zygote. A zygote is a totipotent cell that can develop into a complete organism. The zygote undergoes cell division or cleavage to form an 8-cell mass. Until this stage, the cells are spherical, loosely attached, and remain totipotent. Totipotent cells are capable of developing both the embryonic and the extraembryonic tissues. However, as they continue to divide, they...
Production of Formed Elements
Hemangioblasts are multipotent stem cells originating from the mesoderm. They give rise to hematopoietic stem cells (HSCs), which undergo hematopoiesis to produce all the formed elements of blood. This process is regulated by a complex network of hematopoietic growth factors, including transcription factors, growth factors, and cytokines. These factors stimulate the HSCs to divide and differentiate, though some HSCs remain undifferentiated to maintain a self-renewing pool.
Most HSCs commit to...
Most HSCs commit to...
Structure and Function of Platelets
The cell fragments known as platelets are disc-shaped, with an average diameter of about 3 μm and a thickness of roughly 1 μm. They play a crucial role in the body's vascular clotting system, which also involves plasma proteins, blood cells, and blood vessel tissues.
Platelets are continually replenished, circulating in the bloodstream for 9-12 days before being removed by phagocytes, primarily in the spleen. A microliter of circulating blood contains between 150,000 and 450,000 platelets, with...
Platelets are continually replenished, circulating in the bloodstream for 9-12 days before being removed by phagocytes, primarily in the spleen. A microliter of circulating blood contains between 150,000 and 450,000 platelets, with...
Development of Blood Vessels
The development of the vascular system in a fetus is a complex and intricate process that begins as early as 15 to 16 days post-conception. This process starts outside the embryo, specifically in the mesoderm of the yolk sac, chorion, and connecting stalk. Approximately two days later, the formation of blood vessels occurs within the embryo itself.
The initial formation of this system is facilitated by the small amount of yolk present in the ovum and yolk sac. Blood vessels originate from...
The initial formation of this system is facilitated by the small amount of yolk present in the ovum and yolk sac. Blood vessels originate from...

