merozoites

メロゾイト

WordNet

1. a cell that arises from the asexual division of a parent sporozoan during its life cycle

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/05/18 06:05:32」(JST)

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Cellular structure of a typical, generalised Apicomplexan: 1-polar ring, 2-conoid, 3-micronemes, 4-rhoptries, 5-nucleus, 6-nucleolus, 7-mitochondria, 8-posterior ring, 9-alveoli, 10-golgi apparatus, 11-micropore.

Apicomplexa life cycle stages have evolved to allow apicomplexan intracellular parasites to survive the wide variety of environments they are exposed to during their complex life cycles. Each stage is typified by a cellular variety with a distinct morphology and biochemistry.

Not all apicomplexa develop all the following cellular varieties and division methods. This presentation is intended as an outline of a hypothetical generalised apicomplexan organism.

Methods of asexual replication

See also: Fission (biology)

Apicomplexans (sporozoans) replicate via ways of multiple fission (also known as schizogony). These ways include gametogony, sporogony and merogony, although the latter is sometimes referred to as schizogony, despite its general meaning.

Merogony is an asexually reproductive process of apicomplexa. After infecting a host cell, a trophozoite (see glossary below) increases in size while repeatedly replicating its nucleus and other organelles. During this process, the organism is known as a meront or schizont. Cytokinesis next subdivides the multinucleated schizont into numerous identical daughter cells called merozoites (see glossary below), which are released into the blood when the host cell ruptures. Organisms whose life cycles rely on this process include Theileria, Babesia, as well as the malaria parasite Plasmodium.

Sporogony is a type of sexual and asexual reproduction. It involves karyogamy, the formation of a zygote which is followed by meiosis and multiple fission. This results in the production of sporozoites.

Other forms of replication include endodyogeny and endopolygeny.

Endodyogeny is a process of asexual reproduction, favoured by parasites such as Toxoplasma gondii. It involves an unusual process in which two daughter cells are produced inside a mother cell, which is then consumed by the offspring prior to their separation.

Endopolygeny is the division into several organisms at once by internal budding.

Glossary of cell types

An ookinete (motile), a sporozoite (motile) and a merozoite (non-motile) of Plasmodium falciparum.

Infectious stages

A sporozoite (G. sporos, seed + zōon, animal) is the cell form that infects new hosts. In Plasmodium, for instance, the sporozoites are cells that develop in the mosquito's salivary glands, leave the mosquito during a blood meal, and enter liver cells (hepatocytes) where they multiply. Cells infected with sporozoites eventually burst, releasing merozoites into the bloodstream. Sporozoites are motile and they move by gliding.

A merozoite (G. meros, part [of a series], +zōon, animal) is the result of merogony that takes place within a host cell. In coccidiosis, merozoites form the first phase of the internal life cycle of coccidian. In the case of Plasmodium, merozoites infect red blood cells and then rapidly reproduce asexually. The red blood cell host is destroyed by this process, which releases many new merozoites that go on to find new blood-borne hosts. Merozoites are non-motile.

A gametocyte (G. gametēs, partner + kytos, hollow) is a name given to a parasite's gamete-forming cells. A male gametocyte divides to give many flagellated microgametes, whereas the female gametocyte differentiates to a macrogamete.

An ookinete (G. ōon, egg + kinētos, motile) is a fertilised zygote capable of moving spontaneously. It penetrates epithelial cells lining the midgut of mosquitos to form a thick-walled structure known as an oocyst under the mosquito's outer gut lining. Ookinetes are motile and they move by gliding.

Feeding stages

A trophozoite (G. trophē, nourishment + zōon, animal) is the activated, intracellular feeding stage in the apicomplexan life cycle. After gorging itself on its host, the trophozoite undergoes schizogony and develops into a schizont, later releasing merozoites.

A bradyzoite (G. bradys, slow + zōon, animal) is a sessile, slow-growing form of zoonotic microorganisms such as Toxoplasma gondii, among others responsible for parasitic infections. In chronic (latent) toxoplasmosis, bradyzoite microscopically presents as clusters enclosed by an irregular crescent-shaped wall (a pseudocyst), in infected muscle and brain tissues.

A tachyzoite (G. tachys, fast + zōon, animal), contrasting with a bradyzoite, is a form typified by rapid growth and replication. Tachyzoites are motile forms of coccidians that form tissue cysts, such as Toxoplasma and Sarcocystis. Typically infecting cellular vacuoles, tachyzoites divide by endodyogeny and endopolygeny.

An oocyst (G. ōon, egg + kystis, bladder) is a hardy, thick-walled spore able to survive for lengthy periods outside a host. The zygote develops within the spore, which acts to protect it during transfer to new hosts. Organisms that create oocysts include Plasmodium, Cryptosporidium and Toxoplasma.

• Lifecycle of the Babesia parasite

• Lifecycle of the Eimeria parasite

• Erythrocytic lifecycle of the Plasmodium parasite

• Lifecycle of the Toxoplasma parasite

See also

• Trematode lifecycle stages

References

UpToDate Contents

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• 1. Babesiosis: Microbiology, epidemiology, and pathogenesis
• 2. マラリアの発症機序 pathogenesis of malaria
• 3. 赤血球表面抗原および細胞骨格蛋白質の異常によるマラリアに対する防御 protection against malaria by abnormalities in red cell surface antigens and cytoskeletal proteins
• 4. Babesiosis: Clinical manifestations and diagnosis
• 5. Non-immune hemolytic anemia due to systemic disease

English Journal

• Disrupting the Allosteric Interaction between the Plasmodium falciparum cAMP-dependent Kinase and Its Regulatory Subunit.

• Littler DR1, Bullen HE2, Harvey KL2,3, Beddoe T4, Crabb BS1,2,3, Rossjohn J1,5,6, Gilson PR7,2.
• The Journal of biological chemistry.J Biol Chem.2016 Dec 2;291(49):25375-25386. Epub 2016 Oct 13.
• The ubiquitous second messenger cAMP mediates signal transduction processes in the malarial parasite that regulate host erythrocyte invasion and the proliferation of merozoites. In Plasmodium falciparum, the central receptor for cAMP is the single regulatory subunit (R) of protein kinase A (PKA). To
• PMID 27738107

• Transfected Babesia bovis Expressing a Tick GST as a Live Vector Vaccine.

• Oldiges DP1, Laughery JM2, Tagliari NJ3, Leite Filho RV3, Davis WC2, da Silva Vaz I Jr1,3, Termignoni C1,4, Knowles DP2,5, Suarez CE2,5.
• PLoS neglected tropical diseases.PLoS Negl Trop Dis.2016 Dec 2;10(12):e0005152. doi: 10.1371/journal.pntd.0005152. eCollection 2016.
• The Rhipicephalus microplus tick is a notorious blood-feeding ectoparasite of livestock, especially cattle, responsible for massive losses in animal production. It is the main vector for transmission of pathogenic bacteria and parasites, including Babesia bovis, an intraerythrocytic apicomplexan pro
• PMID 27911903

• Baculovirus-expressed Plasmodium reichenowi EBA-140 merozoite ligand is host specific.

• Zerka A1, Olechwier A1, Rydzak J1, Kaczmarek R1, Jaskiewicz E2.
• Parasitology international.Parasitol Int.2016 Dec;65(6 Pt A):708-714. doi: 10.1016/j.parint.2016.07.009. Epub 2016 Jul 19.
• Plasmodium reichenowi, an ape malaria parasite is morphologically identical and genetically similar to Plasmodium falciparum, infects chimpanzees but not humans. Genomic studies revealed that all primate malaria parasites belong to Laverania subgenus. Laverania parasites exhibit strict host specific
• PMID 27443851

Japanese Journal

• Cloning and Characterization of a 2-Cys Peroxiredoxin from Babesia gibsoni

• MASATANI Tatsunori,ASADA Masahito,ICHIKAWA-SEKI Madoka,USUI Miho,TERKAWI Mohamad A.,HAYASHI Kei,KAWAZU Shin-ichiro,XUAN Xuenan
• Journal of Veterinary Medical Science, 2013
• … gibsoni merozoites. …
• NAID 130003362301

• Identification, Cloning and Characterization of BmP41, a Common Antigenic Protein of Babesia microti

• MASATANI Tatsunori,OOKA Hideo,TERKAWI Mohamad A.,CAO Shinuo,LUO Yuzi,ASADA Masahito,HAYASHI Kei,NISHIKAWA Yoshifumi,XUAN Xuenan
• Journal of Veterinary Medical Science, 2013
• … microti merozoites. …
• NAID 130003362150

• Time-Lapse Imaging of Red Blood Cell Invasion by the Rodent Malaria Parasite Plasmodium yoelii

• Yahata Kazuhide,Treeck Moritz,Culleton Richard,Gilberger Tim-Wolf,Kaneko Osamu
• PLoS ONE 7(12), e50780, 2012-12-05
• … yoelii merozoites gradually changes from flat elongated ovals to spherical bodies, a process taking about 60 sec. … During this period merozoites were able to attach to and deform the RBC membrane, but were not able to reorient and invade. … yoelii merozoites may be related to the secretion or activation of invasion-related proteins. …
• NAID 120005230518

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