© M.G. Sergeev, 2018 The most notable shared characteristic of the kingdom is the presence of so-called alveolar pellicle with cortical alveoli: flattened vesicles packed into a continuous layer supporting the cell membrane, typically forming a flexible pellicle. This looks like as a cell envelope consisting from 3 membranes. These alveoli often includes plates from peptides, glycopeptids, calcium carbonate... Alveolates have (1) mitochondria with tubular cristae (2) usually extrusomes. [http://palaeos.com/eukarya/alveolata/alveolata.html] Kingdom Phyla Metamonada Fornicata Parabasalia Discoba Euglenophyles Heterolobosea Conoza Alveolata Dinoflagellata Apicomplexa Ciliophora Blastocystae Amoebozoa Lobosa Opisthokonta Microspora Choanomonada Subkingdom Animalia (Metazoa) © M.G. Sergeev, 2018 Phylum Dinoflagellata = Peridiniophyles Usually unicellular, up to 2 mm, sometimes colonial or multicellular. Phototrophs, or chemotrophs, or photochemotrophs. Free-living or commensalic or parasitic (not associated with humans!). Alveoli (if present) usually support overlapping cellulose plates. One nucleus, closed mitosis. Prokaryotic ribosomes. Chloroplasts present ot absent, with 3 membranes (resulted from the secondary symbiosis) Flagella - two different (transverse and longitudinal), extremely different. Mainly haplobionts with sexual reproduction. About 2 000 species. Pfisteria piscida Endoparasites Oodinium [www.jochemnet.de/fiu/bot4404/BOT4404_5.html] Several species are the intranuclear parasites (!) of other protists [Coats, Park, 2002] In warm waters of oceans and seas, dinoflagellates sometimes can bloom in concentrations of more than million cells per millilitre. Under such circumstances they can produce toxins (generally called dinotoxins) in quantities capable of killing fish and accumulating in filter feeders such as shellfish, which in turn may be passed on to people who eat them. Toxic dinoflagellates ± dinotoxins, including saxitoxin (paralytic neurotoxin) [Red Tide caused by Dinoflagellates off the Scripps Institution of Oceanography Pier, La Jolla California. Released into the Public Domain, August 2005. P. Alejandro Diaz and Ginny Velasquez (his busbear) Source: English Wikipedia, original upload 13 August 2005 by Intersofia] Kingdom Phyla Metamonada Fornicata Parabasalia Discoba Euglenophyles Heterolobosea Conoza Alveolata Dinoflagellata Apicomplexa Ciliophora Blastocystae Amoebozoa Lobosa Opisthokonta Microspora Choanomonada Subkingdom Animalia (Metazoa) © M.G. Sergeev, 2018 Phylum Apicomplexa = Sporozoa Usually unicellular. Сhemotrophs. Endoparasites. With one nucleus, closed or open mitosis. Prokaryotic ribosomes. Mitochondria usually with tubular or ampular cristae. Flagella - usually absent, may be developed in microgametes. Usually with rather complicated life cycles, often with two host stages and with multiply asexual fissions. Mainly haplobionts with sexual reproduction. About 5 000 species. An apical complex consists of a set of spirally arranged microtubules (the conoid), a secretory body (the rhoptry = a kind of extrusomes) and one or more polar rings. "Malaria". Licensed under CC BY 2.5 via Commons - https://commons.wikimedia.org/wiki/Fil e:Malaria.jpg#/media/File:Malaria.jpg [http://palaeos.com/eukarya/alveolata/alveolata.html] 1 - anterior polar ring, 2 - conoid, 3 - micronemes, 4 - rhoptries, 5 - nucleus, 6 - nucleolus, 7 - mitochondrion, 8 - posterior ring, 9 - alveoli, 10 - Golgi apparatus, 11 - micropore "Apicomplexa structure" by Franciscosp2 - self-made (with xfig in Linux). Licensed under Public Domain via Commons - https://commons.wikimedia.org/wiki/File:Apicomplexa_structure.svg#/media/File:Ap icomplexa_structure.svg Almost all species contain a single ovoid shaped apicoplast. The apicoplast is situated in close proximity to the parasite cell's nucleus and always closely associated with a mitochondrion. It has 4 membranes and its own DNA. The apicoplast is a product of secondary endosymbiosis, and that the apicoplast may be homologous to the secondary chloroplasts of the closely related dinoflagellates. It has been established that the apicoplast is a vital organelle to the parasite's survival. [Протисты, 2007] General pattern of a life cycle 1- zygote (developing in a cyst), 2 - sporozoites, 3 - merozoites, 4 - gametocytes https://commons.wikimedia.org/wiki/File:Apicomplexa_life_cycle_v2.svg Oocyst Sporocysts Sporozoites (Looks like a Matryoshka doll) A sporozoite (G. sporos, seed + zōon, animal) [spZrc()0zcwt,1sp]+] is the cell form that infects new hosts. Cells infected with sporozoites eventually burst, releasing merozoites into the bloodstream. Sporozoites are motile and they move by gliding. Oocyst Sporocysts Sporozoites A merozoite (G. meros, part [of a series], +zōon, animal) is the result of merogony [mc0rZg c ni] - a kind of multiply fissions that takes place within a host cell. Merozoites form the first phase of the internal life cycle of coccidians. In the case of Plasmodium and its relatives, 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. Oocyst Sporocysts Sporozoites A trophozoite (G. trophē, nourishment + zōon, animal) is the activated, intracellular feeding stage in the apicomplexan life cycle. After some development inside the host cell, the trophozoite undergoes merogony [mc0rZg c ni] (a kind of multiply fissions) and develops into a meront. The last one divides and releases numerous (usually) merozoites. Oocyst Sporocysts Sporozoites A gametocyte (G. gametēs, partner + kytos, cell) [gc0mi tc1sawt] 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 one macrogamete. Oocyst Sporocysts Sporozoites Some coccidians which form tissue cysts, such as Toxoplasma and Sarcocystis, may have two different forms of merozoites. A tachyzoite (G. tachys, fast + zōon, animal) is charachtezed by rapid growth and replication. Tachyzoites are usual in intestine epithelial cells and are the motile forms. A bradyzoite (G. bradys, slow + zōon, animal) is a sessile, slow-growing form, among others responsible for parasitic infections. In chronic (latent) toxoplasmosis, bradyzoites microscopically present as clusters enclosed by an irregular crescent-shaped wall (a pseudocyst) (we usually call this structure a tissue cyst) in infected muscle and brain tissues. A next host (definite or intermediate) commonly eat meat with pseudocysts. An oocyst (G. ōon, egg + kystis, bladder) is a hardy, thick-walled cyst, able to survive for lengthy periods outside a host (or - in piroplasms and haemosporidians - without a thick wall per se and in another host). The zygote develops within the cyst, which acts to protect it during transfer to new hosts. An ookinete (G. ōon, egg + kinētos, motile) is a fertilised zygote capable of moving spontaneously. It penetrates epithelial cells lining the midgut of mosquitoes to form a relatively thick-walled structure known as an oocyst under the mosquito's outer gut lining. Ookinetes are motile and they move by gliding. Oocyst Sporocysts Sporozoites Oocyst Sporozoite Sporozoite Sporocyst [Lainson et al., 2007] Main classes with human parasites (1) Coccidea - coccidians (2) Piroplasmorida - piroplasms (3) Haemospororida - haemosporidians Coccidians Coccidians Coccidians are parasites of vertebrates. They are commonly parasites of the epithelial cells of the gut, but may infect other tissues, especially in cases of immune system disorders. The coccidian lifecycle involves merogony, gametogony, and sporogony. During gametogony some trophozoites enlarge and become (one) macrogamete, whereas others divide repeatedly to form several microgametes. Coccidians The fertilized macrogamete forms a zygote that in its turn forms an oocyst with a thick wall that is normally released from the host body. The oocyst usually produces 2 or 4 sporocysts inside and the sporocyst produces 2 or 4 sporozoites inside. Oocyst Sporozoite Sporozoite Sporocyst [Lainson et al., 2007] Isospora and its relatives oocystº2 sporocystsº 8 (4 x 2) sporozoites Isospora belli = Cystoisospora belli cystoisosporiasis (also isosporiasis, isosporosis) (1) An oocyst is released in feces of an infected human. (2) After the oocyst has been released, the zygote matures further and divides into two so-called sporoblast. (3) Each of them creates a cyst wall and becomes a sporocyst. (4) The sporocysts each divide twice, resulting in four sporozoites. (5) Transmission occurs when these mature oocysts are ingested. (6) The sporocysts excyst in the small intestine where sporozoites are released. (7) The sporozoites then invade epithelial cells and merogony is initiated. (8) When the meronts rupture, merozoites are released and continue to invade more epithelial cells. (9) Trophozoites develop into meronts, containing many merozoites. (10) After about one week, development of micro- and macrogametocytes begin in the merozoites (11) Fertilization results in the development of oocysts, which are released in the feces. Cystoisosporiasis — Clinical symptoms: (1) mild diarrhea, (2) abdominal discomfort, (3) low grade fever for approximately one week. Immunocompromised people (for instance, with AIDS) are more severely affected and may experience extreme diarrhea that can lead to weakness, anorexia, and weight loss. Cyclospora cayetanensis