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Merogregarina
''Merogregarina'' is a genus of parasitic alveolate in the phylum Apicomplexa. Species in this genus infect marine invertebrates. Taxonomy This species was described in 1908 by Porter.Porter (1908) A new Schizogregarine, ''Merogregarina amaroucii'' ''nov.gen''., ''nov. sp''., parasitic in the alimentary canal of the composite Ascidian, Amaroucium sp. (Prel. Comm.). Archives de Zoologie Paris (Ser 4) 9 (xliv-xlviii) There is one species in this genus - ''Merogregarina amaroucii''. Description The trophozoites are found in the intestinal lumen. They measure 23-31 microns x 11-15 microns. They are initially ovoid and become vermiform as they mature. The single nucleus lies at the anterior end and has one nucleolus. The trophozoites develop in multinucleated schizonts which give rise to 8-20 merozoite Apicomplexans, a group of intracellular parasites, have life cycle stages that allow them to survive the wide variety of environments they are exposed to during their complex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Merogregarina Amaroucii
''Merogregarina'' is a genus of parasitic alveolate in the phylum Apicomplexa. Species in this genus infect marine invertebrates. Taxonomy This species was described in 1908 by Porter.Porter (1908) A new Schizogregarine, ''Merogregarina amaroucii'' ''nov.gen''., ''nov. sp''., parasitic in the alimentary canal of the composite Ascidian, Amaroucium sp. (Prel. Comm.). Archives de Zoologie Paris (Ser 4) 9 (xliv-xlviii) There is one species in this genus - ''Merogregarina amaroucii''. Description The trophozoites are found in the intestinal lumen. They measure 23-31 microns x 11-15 microns. They are initially ovoid and become vermiform as they mature. The single nucleus lies at the anterior end and has one nucleolus. The trophozoites develop in multinucleated schizonts which give rise to 8-20 merozoites. The merozoites are 5-6 microns x 1 micron. The sporocysts give rise to eight sporozoite Apicomplexans, a group of intracellular parasites, have life cycle stages that allow t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archigregarinorida
The ''Archigregarinorida'' are an order of parasitic alveolates in the phylum Apicomplexa. Species in this order infect marine invertebrates — usually annelids, ascidians, hemichordates and sipunculids. Taxonomy This order was redefined by Levine in 1971. The order currently consists of 76 species in two families — ''Exoschizonidae'' and ''Selenidioididae''. The family ''Exoschizonidae'' contains one genus — ''Exoschizon'' — which has one species. The family ''Selenidioididae'' has six genera: ''Filipodium'' with 3 species, ''Merogregarina'' with one species, ''Meroselenidium'' with one species, '' Platyproteum'' with one species, ''Selenidioides'' with 11 species and ''Veloxidium'' with one species. Phylogenetics DNA studies suggest that the archigregarines are ancestral to the other gregarines. Phylogenetic analysis suggests that this group is paraphyletic and will need division. The Neogregarinorida appear to be derived from the Eugregarinorida. Assuming this is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenidioididae
The ''Selenidioididae'' are a family of parasitic alveolates in the phylum Apicomplexa. Species in this order infect marine invertebrates. Taxonomy The order Archigregarinorida was redefined by Levine in 1971Levine N D (1971) Taxonomy of the Archigregarinorida and Selenidiidae (Protozoa, Apicomplexa) J Euk Micro 18 (4) 704-717 DOI: 10.1111/j.1550-7408.1971.tb03401.x and divided into two families: Exoschizonidae The Exoschizonidae are a family in the phylum Apicomplexa. History This family was created by Levine in 1971.Levine ND (1971) Taxonomy of the Archigregarinorida and Selenidiidae (Protozoa, Apicomplexa) J Euk Microbiol 18 (4) 704–717 Taxonom ... and Selenidioididae. There are seven genera and 74 species recognised in this family. Description Species in this family undergo asexual schizogony. Life cycle The species in the family infect the gastrointestinal tract and are presumably transmitted by the orofaecal route but the details of this mechanism are prese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryota
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacteria and Archaea (both prokaryotes) make up the other two domains. The eukaryotes are usually now regarded as having emerged in the Archaea or as a sister of the Asgard archaea. This implies that there are only two domains of life, Bacteria and Archaea, with eukaryotes incorporated among archaea. Eukaryotes represent a small minority of the number of organisms, but, due to their generally much larger size, their collective global biomass is estimated to be about equal to that of prokaryotes. Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the Proterozoic eon, likely as Flagellated cell, flagellated phagotrophs. Their name comes from the Greek language, Greek wikt:εὖ, εὖ (''eu'', "well" or "good") and wikt:� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Nucleus
The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm; and the nuclear matrix, a network within the nucleus that adds mechanical support. The cell nucleus contains nearly all of the cell's genome. Nuclear DNA is often organized into multiple chromosomes – long stands of DNA dotted with various proteins, such as histones, that protect and organize the DNA. The genes within these chromosomes are structured in such a way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the cell by regulating g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sporozoite
Apicomplexans, a group of intracellular parasites, have life cycle stages that allow them to survive the wide variety of environments they are exposed to during their complex life cycle. Each stage in the life cycle of an apicomplexan organism 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 Apicomplexans (sporozoans) replicate via ways of multiple fission (also known as schizogony). These ways include , and , 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 orga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleolus
The nucleolus (, plural: nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis, which is the synthesis of ribosomes. The nucleolus also participates in the formation of signal recognition particles and plays a role in the cell's response to stress. Nucleoli are made of proteins, DNA and RNA, and form around specific chromosomal regions called nucleolar organizing regions. Malfunction of nucleoli can be the cause of several human conditions called "nucleolopathies" and the nucleolus is being investigated as a target for cancer chemotherapy. History The nucleolus was identified by bright-field microscopy during the 1830s. Little was known about the function of the nucleolus until 1964, when a study of nucleoli by John Gurdon and Donald Brown in the African clawed frog '' Xenopus laevis'' generated increasing interest in the function and detailed structure of the nucleolus. They found that 25% of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylum
In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature for algae, fungi, and plants accepts the terms as equivalent. Depending on definitions, the animal kingdom Animalia contains about 31 phyla, the plant kingdom Plantae contains about 14 phyla, and the fungus kingdom Fungi contains about 8 phyla. Current research in phylogenetics is uncovering the relationships between phyla, which are contained in larger clades, like Ecdysozoa and Embryophyta. General description The term phylum was coined in 1866 by Ernst Haeckel from the Greek (, "race, stock"), related to (, "tribe, clan"). Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguished them as a group ("a self-contain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
