The kinetoplast is a specialized region of the mitochondria of trypanosomatids that harbors the most complex and unusual mitochondrial DNA found in nature. Kinetoplast DNA (kDNA) is composed of thousands of circular molecules topologically interlocked to form a single network. Two types of DNA circles are present in the kinetoplast: minicircles (0.5–10 kb) and maxicircles (20–40 kb). Knowledge of kinetoplast architecture is crucial to understanding the replication and segregation of kDNA circles because the molecules involved in these processes are precisely positioned in functional domains throughout the kinetoplast. The fine structure of the kinetoplast was revealed in early electron microscopy (EM) studies. However, an understanding of the topological organization of kDNA was only demonstrated after the development of protocols to separate kDNA from nuclear DNA, followed by EM observations. Electron microscopy analysis of thin sections of trypanosomatids, spreading of isolated kDNA networks onto EM grids, deep-etching studies, and cytochemical and immunocytochemical approaches are examples of techniques that were useful for elucidating the structure and replication of the kinetoplast. Recently, atomic force microscopy has joined this set of techniques and improved our knowledge about the kDNA network and revealed new details about kDNA topology in trypanosomatids.

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锥虫的动质体：从电子显微镜的早期研究到原子力显微镜的最新进展

动质体是锥虫线粒体的一个特殊区域，它包含自然界中发现的最复杂和最不寻常的线粒体 DNA。Kinetoplast DNA (kDNA) 由数以千计的环状分子拓扑互锁形成一个网络。动质体中存在两种类型的 DNA 环：小环 (0.5-10 kb) 和大环 (20-40 kb)。动质体结构的知识对于理解 kDNA 环的复制和分离至关重要，因为参与这些过程的分子精确地定位在整个动质体的功能域中。早期电子显微镜 (EM) 研究揭示了动质体的精细结构。然而，对 kDNA 拓扑组织的理解只有在开发了将 kDNA 与核 DNA 分离的协议之后才得以证明，然后是 EM 观察。锥虫的薄切片的电子显微镜分析、孤立的 kDNA 网络在 EM 网格上的传播、深蚀刻研究以及细胞化学和免疫细胞化学方法是有助于阐明动质体的结构和复制的技术示例。最近，原子力显微镜加入了这组技术，提高了我们对 kDNA 网络的了解，并揭示了锥虫中 kDNA 拓扑结构的新细节。和细胞化学和免疫细胞化学方法是用于阐明动质体的结构和复制的技术的例子。最近，原子力显微镜加入了这组技术，提高了我们对 kDNA 网络的了解，并揭示了锥虫中 kDNA 拓扑结构的新细节。和细胞化学和免疫细胞化学方法是用于阐明动质体的结构和复制的技术的例子。最近，原子力显微镜加入了这组技术，提高了我们对 kDNA 网络的了解，并揭示了锥虫中 kDNA 拓扑结构的新细节。