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Microneme
Micronemes are secretory organelles, possessed by parasitic apicomplexans. Micronemes are located on the apical third of the protozoan body. They are surrounded by a typical unit membrane. On electron microscopy they have an electron-dense matrix due to the high protein content. They are specialized secretory organelles important for host-cell invasion and gliding motility. These organelles secrete several proteins such as the '' Plasmodium falciparum'' apical membrane antigen-1, or PfAMA1, and Erythrocyte family antigen, or EBA, family proteins. These proteins specialize in binding to erythrocyte surface receptors and facilitating erythrocyte entry. Only by this initial chemical exchange can the parasite enter into the erythrocyte via actin-myosin motor complex. It has been posited that this organelle works cooperatively with its counterpart organelle, the rhoptry, which also is a secretory organelle. It is possible that, while the microneme initiates erythrocyte-binding, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasitophorous Vacuole
The parasitophorous vacuole (PV) is a structure produced by apicomplexan parasites in the cells of its host. The PV allows the parasite to develop while protected from the phagolysosomes of the host cell. The PV is a bubble-like compartment made of plasma membrane; the compartment contains cytoplasm and the parasite. The PV allows the parasite to exist and grow within the cell while protecting the parasite from the host cell defense mechanisms. The PV prevents the acidification of the compartment, the mechanism by which the lysosomes of the host cell would normally destroy an invading parasite. Parasites that form a parasitophorous vacuole as part of their infection process include '' Plasmodium falciparum'', which causes malaria and ''Toxoplasma gondii'', which causes toxoplasmosis. The parasitophorous vacuole is formed during cell invasion, when the parasite uses part of the membrane of the host cell to form a parasitophorous vacuolar membrane (PVM). The PVM surrounds the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasmodium Falciparum
''Plasmodium falciparum'' is a unicellular protozoan parasite of humans, and the deadliest species of ''Plasmodium'' that causes malaria in humans. The parasite is transmitted through the bite of a female '' Anopheles'' mosquito and causes the disease's most dangerous form, falciparum malaria. It is responsible for around 50% of all malaria cases. ''P. falciparum'' is therefore regarded as the deadliest parasite in humans. It is also associated with the development of blood cancer (Burkitt's lymphoma) and is classified as a Group 2A (probable) carcinogen. The species originated from the malarial parasite '' Laverania'' found in gorillas, around 10,000 years ago. Alphonse Laveran was the first to identify the parasite in 1880, and named it ''Oscillaria malariae''. Ronald Ross discovered its transmission by mosquito in 1897. Giovanni Battista Grassi elucidated the complete transmission from a female anopheline mosquito to humans in 1898. In 1897, William H. Welch created the n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apicomplexa
The Apicomplexa (also called Apicomplexia) are a large phylum of parasitic alveolates. Most of them possess a unique form of organelle that comprises a type of non-photosynthetic plastid called an apicoplast, and an apical complex structure. The organelle is an adaptation that the apicomplexan applies in penetration of a host cell. The Apicomplexa are unicellular and spore-forming. All species are obligate endoparasites of animals, except '' Nephromyces'', a symbiont in marine animals, originally classified as a chytrid fungus. Motile structures such as flagella or pseudopods are present only in certain gamete stages. The Apicomplexa are a diverse group that includes organisms such as the coccidia, gregarines, piroplasms, haemogregarines, and plasmodia. Diseases caused by Apicomplexa include: * Babesiosis ('' Babesia'') * Malaria (''Plasmodium'') * Cryptosporidiosis ('' Cryptosporidium parvum'') * Cyclosporiasis ('' Cyclospora cayetanensis'') * Cystoisosporiasis ('' Cys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duffy Binding Proteins
In molecular biology, Duffy binding proteins are found in Plasmodium. ''Plasmodium vivax'' and '' Plasmodium knowlesi'' merozoites invade ''Homo sapiens'' erythrocytes that express Duffy blood group surface determinants. The Duffy receptor family is localised in micronemes, an organelle found in all organisms of the phylum Apicomplexa. The presence of duffy-binding-like domains defines the family of erythrocyte binding-like proteins (EBL), a family of cell invasion proteins universal among ''Plasmodium''. These other members may use some other receptor, for example Glycophorin A Glycophorin A (MNS blood group), also known as GYPA, is a protein which in humans is encoded by the ''GYPA'' gene. GYPA has also recently been designated CD235a ( cluster of differentiation 235a). Function Glycophorins A (GYPA; this protein) .... The other universal invasion protein is reticulocyte binding protein homologs. Both families are essential for cell invasion, as they function cooperati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhoptry
A rhoptry is a specialized secretory organelle. They are club-shaped organelles connected by thin necks to the extreme apical pole of the parasite. These organelles, like micronemes, are characteristic of the motile stages of Apicomplexa protozoans. They can vary in number and shape and contain numerous enzymes that are released during the penetration process. The proteins they contain are important in the interaction between the host and the parasite, including the formation of the parasitophorous vacuole The parasitophorous vacuole (PV) is a structure produced by apicomplexan parasites in the cells of its host. The PV allows the parasite to develop while protected from the phagolysosomes of the host cell. The PV is a bubble-like compartment ma .... References Organelles {{Cell-biology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid resid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gliding Motility
Gliding motility is a type of translocation used by microorganisms that is independent of propulsive structures such as flagella, pili, and fimbriae. Gliding allows microorganisms to travel along the surface of low aqueous films. The mechanisms of this motility are only partially known. Twitching motility also allows microorganisms to travel along a surface, but this type of movement is jerky and uses pili as its means of transport. Bacterial gliding is a type of gliding motility that can also use pili for propulsion. The speed of gliding varies between organisms, and the reversal of direction is seemingly regulated by some sort of internal clock. For example the apicomplexans are able to travel at fast rates between 1–10 µm/s. In contrast ''Myxococcus xanthus'' bacteria glide at a rate of 0.08 µm/s. Cell-invasion and gliding motility have TRAP (thrombospondin-related anonymous protein), a surface protein, as a common molecular basis that is both essential for i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organelles
In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as organs are to the body, hence ''organelle,'' the suffix ''-elle'' being a diminutive. Organelles are either separately enclosed within their own lipid bilayers (also called membrane-bound organelles) or are spatially distinct functional units without a surrounding lipid bilayer (non-membrane bound organelles). Although most organelles are functional units within cells, some function units that extend outside of cells are often termed organelles, such as cilia, the flagellum and archaellum, and the trichocyst. Organelles are identified by microscopy, and can also be purified by cell fractionation. There are many types of organelles, particularly in eukaryotic cells. They include structures that make up the endomembrane system (such as the nuclear envelope, endoplasmic reticulum, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apical Membrane Antigen 1
In molecular biology, apical membrane antigen 1 is a novel antigen of ''Plasmodium falciparum'' which has been cloned. It contains a hydrophobic domain typical of an integral membrane protein. The antigen is designated apical membrane antigen 1 (AMA-1) by virtue of appearing to be located in the apical complex. AMA-1 appears to be transported to the merozoite surface close to the time of schizont rupture. The 66kDa merozoite surface antigen (PK66) of ''Plasmodium knowlesi'', a simian malaria, possesses vaccine-related properties believed to originate from a receptor-like role in parasite invasion of erythrocytes. The sequence of PK66 is conserved throughout ''Plasmodium'', and shows high similarity to ''P. falciparum'' AMA-1. Following schizont rupture, the distribution of PK66 changes in a coordinate manner associated with merozoite invasion. Prior to rupture, the protein is concentrated at the apical end, following which it distributes itself entirely across the surface of the fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Blood Cell
Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "hollow vessel", with ''-cyte'' translated as "cell" in modern usage), are the most common type of blood cell and the vertebrate's principal means of delivering oxygen (O2) to the body tissues—via blood flow through the circulatory system. RBCs take up oxygen in the lungs, or in fish the gills, and release it into tissues while squeezing through the body's capillaries. The cytoplasm of a red blood cell is rich in hemoglobin, an iron-containing biomolecule that can bind oxygen and is responsible for the red color of the cells and the blood. Each human red blood cell contains approximately 270 million hemoglobin molecules. The cell membrane is composed of proteins and lipids, and this structure provides properties essential for phys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Merozoite Surface Protein
Merozoite surface proteins are both integral and peripheral membrane proteins found on the surface of a merozoite, an early life cycle stage of a protozoan. Merozoite surface proteins, or MSPs, are important in understanding malaria, a disease caused by protozoans of the genus Plasmodium. During the asexual blood stage of its life cycle, the malaria parasite enters red blood cells to replicate itself, causing the classic symptoms of malaria. These surface protein complexes are involved in many interactions of the parasite with red blood cells and are therefore an important topic of study for scientists aiming to combat malaria. Forms The most common form of MSPs are anchored to the merozoite surface with glycophosphatidylinositol, a short glycolipid often used for protein anchoring. Additional forms include integral membrane proteins and peripherally associated proteins, which are found to a lesser extent than glycophosphatidylinositol anchored proteins, or (GPI)-anchored protein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
