Kinetoplast

Kinetoplastida or Kinetoplasteaas a class is a group of flagellated protists belonging to kinetoplast phylum Euglenozoa[3] [4] and characterised by the presence of a distinctive organelle called the kinetoplast hence the namekinetoplast, a granule containing a large mass of DNA. The group includes a number of parasites responsible for serious diseases in humans and other animals, as kinetoplast as various forms found in soil and aquatic environments, kinetoplast. The organisms are commonly referred to as "kinetoplastids" or "kinetoplasts". The kinetoplastids were first defined by Bronislaw M.

Federal government websites often end in. The site is secure. Unique to the single mitochondrion of unicellular flagellates of the order Kinetoplastida, kDNA is best known as a giant network of thousands of catenated circular DNAs an electron micrograph of a network is shown in Fig. The kDNA circles are of two types, maxicircles and minicircles. Maxicircles usually range from 20 to 40 kb, depending on the species, and are present in a few dozen identical copies per network. Minicircles, present in several thousand copies per network, are usually nearly identical in size 0.

Kinetoplast

This page has been archived and is no longer updated. Kinetoplastids are flagellated protozoans, which are unicellular eukaryotic organisms. They include free-living microorganisms, as well as parasites of diverse invertebrate, vertebrate, and plant species. Some kinetoplastids are responsible for serious human diseases, such as Chagas disease and sleeping sickness caused by Trypanosoma cruzi and Trypanosoma brucei , respectively , and the various forms of cutaneous and visceral leishmaniasis caused by Leishmania spp. The network of rings in kDNA forms a beautiful structure. Observed under the electron microscope, it resembles the chainmail that medieval knights wore under their plate armor for protection. In their research on kDNA, scientists eager to understand the function of this amazing structure made a second unexpected discovery: a novel, complex mechanism for RNA processing of mitochondrial transcripts, now known as RNA editing. Investigators from different disciplines have been working hard over the past decades to gather clues to explain the unusual properties of kDNA. Today there are still many questions left to answer. The first tools developed for the study of cells and tissues were optical microscopes. These microscopes use visible light and one or more lenses to magnify small objects. Since their invention about years ago, scientists have constructed different models and types of light microscopes. In the early twentieth century, with the aid of photographic cameras, microscopists obtained the first micrographs of cell structures.

Kinetoplast editing and mitochondrial genomic organization in the cryptobiid kinetoplastid protozoan Trypanoplasma borreli. To date, there is general agreement among scientists that kDNA can exist in a vast diversity of structures, kinetoplast now biologists are trying to understand the biological significance of the kDNA network, different kDNA structures, kinetoplast, and the role of kDNA in parasitism. Cells in insets are all at the same scale.

Federal government websites often end in. The site is secure. 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. 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.

Federal government websites often end in. The site is secure. 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. 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.

Kinetoplast

Situated near the nucleus, kinetoplasts are made up of a dense structure consisting of DNA kDNA within the mitochondria. As an extranuclear bundle of DNA, kinetoplast are distinguishing features among some eukaryotes that are collectively known as kinetoplastids members of the order Kinetoplastida. Based on molecular studies, kinetoplasts have been shown to contain two types of circular DNA. These include:. Kinetoplasts were first identified in the s by scientists like William Trager using the light microscope. At the time, they were described as tiny spherical or rod-shaped structures located behind the basal body of the flagellum.

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Shapiro T. Martin, and D. When scientists began studying the transcription of the mitochondrial genes , they found unexpected clues to answer these question. Solutions to this problem could be that its minicircles segregate by the first model or that minicircle exchange occurs during mating to homogenize and sustain the minicircle repertoire RNA editing and mitochondrial genomic organization in the cryptobiid kinetoplastid protozoan Trypanoplasma borreli. Read Edit View history. The association of the replicating kinetoplast to the two basal bodies causes it to develop a domed appearance. Trypanosoma brucei , the parasite which causes African trypanosomiasis African sleeping sickness , is an example of a trypanosome with a kinetoplast. All of the species exhibited similar sizes of kDNA Table 1 and appeared as intact and massive networks with a high concentration of DNA fibers distributed throughout their structure. Simpson L. Wright, A. Instead of being condensed into a single globular bundle Fig. Categories : Excavata classes Kinetoplastids. Eukaryote kingdoms: seven or nine?

Understanding the self-assembly and replication of this structure are not only major open questions in biology but can also inform the design of synthetic topological materials. Here, we report the first high-resolution, single-molecule study of kDNA network topology using AFM and steered molecular dynamics simulations.

Protistologica 15 : Therefore, until more conserved genes can be analyzed, the precise evolution of the early-branching bodonids cannot be definitively traced; Fig. Mechanism of control by spermidine. Green Science. Journal of Biological Chemistry. Minicircle dimers, but no larger oligomers, were also found, and they were relatively abundant only in C. Selenaionida Selenaionidae. The effect of topoisomerase II inhibitors on the kinetoplast ultrastructure. Some kinetoplastids are responsible for serious human diseases, such as Chagas disease and sleeping sickness caused by Trypanosoma cruzi and Trypanosoma brucei , respectively , and the various forms of cutaneous and visceral leishmaniasis caused by Leishmania spp. Gull, K.