Kinetoplast

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A kinetoplast is a network of circular DNA called kDNA inside a mitochondrion that contains many copies of the mitochondrial genome. Kinetoplasts are only found in Excavata of the class Kinetoplastida. The variation in the structures of kinetoplasts may reflect phylogenic relationships between kinetoplastids. In Trypanosoma brucei this cytoskeletal connection is called the tripartite attachment complex and includes the protein p In trypanosomes , a group of flagellated protozoans, the kinetoplast exists as a dense granule of DNA within the mitochondrion.

Kinetoplast

Kinetoplastida or Kinetoplastea , as a class is a group of flagellated protists belonging to the phylum Euglenozoa , [3] [4] and characterised by the presence of a distinctive organelle called the kinetoplast hence the name , 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 well as various forms found in soil and aquatic environments. The organisms are commonly referred to as "kinetoplastids" or "kinetoplasts". The kinetoplastids were first defined by Bronislaw M. Honigberg in as the members of the flagellated protozoans. One family of kinetoplastids, the trypanosomatids, is notable as it includes several genera which are exclusively parasitic. Bodo is a typical genus within kinetoplastida, which also includes various common free-living species which feed on bacteria. Others include Cryptobia and the parasitic Leishmania. Honigberg created the taxonomic names Kinetoplastida and Kinetoplastea in Kinetoplastea is more widely used as the class, [6] [7] [8] [9] [10] while Kinetoplastida is mostly used to designate the order , [4] [11] [12] [13] but is also used as a class. Kinetoplastida is divided into two subclasses - Metakinetoplastina and Prokinetoplastina. Kinetoplastids are eukaryotic and possess normal eukaryotic organelles, for example the nucleus , mitochondrion, golgi apparatus and flagellum.

The advent of AFM in opened up an exciting perspective for the study of biological specimens [ 38 ]. Imasidae Malawimonadidae. The genetic information for editing is provided by guide RNAs gRNAs that are kinetoplast encoded by minicircles, kinetoplast, kinetoplast a few are encoded by maxicircles.

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.

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

A kinetoplast is a network of circular DNA called kDNA inside a mitochondrion that contains many copies of the mitochondrial genome. Kinetoplasts are only found in Excavata of the class Kinetoplastida. The variation in the structures of kinetoplasts may reflect phylogenic relationships between kinetoplastids. In Trypanosoma brucei this cytoskeletal connection is called the tripartite attachment complex and includes the protein p In trypanosomes , a group of flagellated protozoans, the kinetoplast exists as a dense granule of DNA within the mitochondrion.

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However, molecular studies have indicated that it does not contain minicircles at all De Souza W. Cells in insets are all at the same scale. If the cells do not have a molecular mechanism for proper segregation of their kDNA components, it is likely that they compensate for minicircle loss by undergoing frequent genetic exchange. Gibson, W. PLoS One. There are other molecular transactions involving minicircles and maxicircles. Clusters of DNA molecules forming rosettes were noted along the networks in all of the trypanosomatids studied Figure 8. Therefore, the sample is dried without ever having crossed the liquid-gas phase border, which can majorly distort biological specimens. To prove this idea, researchers designed a very interesting experiment. Therefore, until more conserved genes can be analyzed, the precise evolution of the early-branching bodonids cannot be definitively traced; Fig. A novel trypanoplasm-like flagellate Jarrellia atramenti n.

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.

Kinetoplastida: Bodonidae and ciliates from the blowhole of a stranded pygmy sperm whale Kogia breviceps Physeteridae : morphology, life cycle and potential pathogenicity. Two types of DNA rings are present in the kinetoplast lumen: minicircles typically ranging in size from 0. The observation of transversal sections of kinetoplast in various trypanosomatids revealed that this structure is surrounded by the double membrane of mitochondria, from which cristae can occasionally be seen projecting into the lumen. Trypanosoma cruzi , known to invade cardiac myocytes left , Trypanosoma brucei protozoa among red blood cells middle and Leishmania major , a parasitic protozoa right. Deep-etching analysis also provided a three-dimensional view of the kinetoplast of the endosymbiont-bearing trypanosomatid Angomonas deanei , as presented by Cavalcanti et al. Other cytoskeletal structures include the specialised attachment between the flagellum and the kinetoplast. Clusters of DNA molecules forming rosettes were noted along the networks in all of the trypanosomatids studied Figure 8. According to this logic, it is inevitable that relaxed, compacted DNA circles in the presence of topoisomerase will form a network. Figure 5. In recent years, AFM has been used to study kDNA topology and the effect of drugs on the kinetoplasts of trypanosomatids. This technique revealed that the typical kDNA network of this protozoan was made up of DNA filaments arranged in a less-condensed manner than that of T. Blom, D. 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. In this scenario, the two progeny minicircles could attach to the network at neighboring positions, making it likely that they would be distributed into the same daughter network. Kanaar, R.