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Mannan-binding Lectin
Mannose-binding lectin (MBL), also called mannan-binding lectin or mannan-binding protein (MBP), is a lectin that is instrumental in innate immunity as an opsonin and via the lectin pathway. Structure MBL has an oligomeric structure (400-700 kDa), built of subunits that contain three presumably identical peptide chains of about 30 kDa each. Although MBL can form several oligomeric forms, there are indications that dimers and trimers are biologically inactive as an opsonin and at least a tetramer form is needed for activation of complement. Genes and polymorphisms Human MBL2 gene is located on chromosome 10q11.2-q21. Mice have two homologous genes, but in human the first of them was lost. A low level expression of an MBL1 pseudogene 1 (MBL1P1) was detected in liver. The pseudogene encodes a truncated 51-amino acid protein that is homologous to the MBLA isoform in rodents and some primates. Structural mutations in exon 1 of the human MBL2 gene, at codon 52 (Arg to Cys, allele D), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lectin
Lectins are carbohydrate-binding proteins that are highly specific for sugar groups that are part of other molecules, so cause agglutination of particular cells or precipitation of glycoconjugates and polysaccharides. Lectins have a role in recognition at the cellular and molecular level and play numerous roles in biological recognition phenomena involving cells, carbohydrates, and proteins. Lectins also mediate attachment and binding of bacteria, viruses, and fungi to their intended targets. Lectins are ubiquitous in nature and are found in many foods. Some foods, such as beans and grains, need to be cooked, fermented or sprouted to reduce lectin content. Some lectins are beneficial, such as CLEC11A, which promotes bone growth, while others may be powerful toxins such as ricin. Lectins may be disabled by specific mono- and oligosaccharides, which bind to ingested lectins from grains, legumes, nightshade plants, and dairy; binding can prevent their attachment to the carbohyd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apoptosis
Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes ( morphology) and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, DNA fragmentation, and mRNA decay. The average adult human loses between 50 and 70 billion cells each day due to apoptosis. For an average human child between eight and fourteen years old, approximately twenty to thirty billion cells die per day. In contrast to necrosis, which is a form of traumatic cell death that results from acute cellular injury, apoptosis is a highly regulated and controlled process that confers advantages during an organism's life cycle. For example, the separation of fingers and toes in a developing human embryo occurs because cells between the digits undergo apoptosis. Unlike necrosis, apoptosis produces cell fragments called apop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ficolin
Ficolins are pattern recognition receptors that bind to acetyl groups present in the carbohydrates of bacterial surfaces and mediate activation of the lectin pathway of the complement cascade. Structure Ficolins (Fi+Col+Lin) are a group of oligomeric lectins with N-terminal collagen-like domain and a C-terminal fibrinogen-like domain. The primary ficolin structure contains 288 amino acids. The combination of collagen-like and fibrinogen-like domain allows the protein to form a basic subunit containing a triple helical tail and a trio of globural heads. Ficolins are produced in the liver by hepatocytes and in the lung by alveolar cells type II, neutrophils and monocytes. Role in innate immunity We now know that innate immune recognition mechanisms are sophisticated. Exocrine secretions provide a variety of soluble factors that are able to protect the body from potential pathogens. Together with pentraxins, collectins and C1q molecules, ficolins constitute the soluble pattern- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SARS-CoV-2
Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) is a strain of coronavirus that causes COVID-19 (coronavirus disease 2019), the respiratory illness responsible for the ongoing COVID-19 pandemic. The virus previously had a provisional name, 2019 novel coronavirus (2019-nCoV), and has also been called the human coronavirus 2019 (HCoV-19 or hCoV-19). First identified in the city of Wuhan, Hubei, China, the World Health Organization declared the outbreak a public health emergency of international concern on January 30, 2020, and a pandemic on March 11, 2020. SARS‑CoV‑2 is a positive-sense single-stranded RNA virus that is contagious in humans. SARS‑CoV‑2 is a virus of the species '' severe acute respiratory syndrome–related coronavirus'' (SARSr-CoV), related to the SARS-CoV-1 virus that caused the 2002–2004 SARS outbreak. Despite its close relation to SARS-CoV-1, its closest known relatives, with which it forms a sister group, are the derived ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leishmania
''Leishmania'' is a parasitic protozoan, a single-celled organism of the genus '' Leishmania'' that are responsible for the disease leishmaniasis. They are spread by sandflies of the genus ''Phlebotomus'' in the Old World, and of the genus ''Lutzomyia'' in the New World. At least 93 sandfly species are proven or probable vectors worldwide.WHO (2010) Annual report. Geneva Their primary hosts are vertebrates; ''Leishmania'' commonly infects hyraxes, canids, rodents, and humans. History Members of an ancient genus of the ''Leishmania'' parasite, '' Paleoleishmania'', have been detected in fossilized sand flies dating back to the early Cretaceous period. The first written reference to the conspicuous symptoms of cutaneous leishmaniasis surfaced in the Paleotropics within oriental texts dating back to the 7th century BC (allegedly transcribed from sources several hundred years older, between 1500 and 2000 BC). Due to its broad and persistent prevalence throughout antiquity as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasite
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has characterised parasites as "predators that eat prey in units of less than one". Parasites include single-celled protozoans such as the agents of malaria, sleeping sickness, and amoebic dysentery; animals such as hookworms, lice, mosquitoes, and vampire bats; fungi such as honey fungus and the agents of ringworm; and plants such as mistletoe, dodder, and the broomrapes. There are six major parasitic strategies of exploitation of animal hosts, namely parasitic castration, directly transmitted parasitism (by contact), trophicallytransmitted parasitism (by being eaten), vector-transmitted parasitism, parasitoidism, and micropredation. One major axis of classification concerns invasiveness: an endoparasite lives inside the host's body ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streptococci
''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs along a single axis, so as they grow, they tend to form pairs or chains that may appear bent or twisted. This differs from staphylococci, which divide along multiple axes, thereby generating irregular, grape-like clusters of cells. Most streptococci are oxidase-negative and catalase-negative, and many are facultative anaerobes (capable of growth both aerobically and anaerobically). The term was coined in 1877 by Viennese surgeon Albert Theodor Billroth (1829–1894), by combining the prefix "strepto-" (from ), together with the suffix "-coccus" (from Modern , from .) In 1984, many bacteria formerly grouped in the genus ''Streptococcus'' were separated out into the genera '' Enterococcus'' and '' Lactococcus''. Currently, over 50 spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salmonella
''Salmonella'' is a genus of rod-shaped (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two species of ''Salmonella'' are '' Salmonella enterica'' and '' Salmonella bongori''. ''S. enterica'' is the type species and is further divided into six subspecies that include over 2,600 serotypes. ''Salmonella'' was named after Daniel Elmer Salmon (1850–1914), an American veterinary surgeon. ''Salmonella'' species are non-spore-forming, predominantly motile enterobacteria with cell diameters between about 0.7 and 1.5 μm, lengths from 2 to 5 μm, and peritrichous flagella (all around the cell body, allowing them to move). They are chemotrophs, obtaining their energy from oxidation and reduction reactions, using organic sources. They are also facultative anaerobes, capable of generating ATP with oxygen ("aerobically") when it is available, or using other electron acceptors or fermentation ("anaerobically") when oxygen is not available. ''Salmonell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Influenza A
'' A virus'' (''IAV'') causes influenza in birds and some mammals, and is the only species of the genus ''Alphainfluenzavirus'' of the virus family ''Orthomyxoviridae''. Strains of all subtypes of influenza A virus have been isolated from wild birds, although disease is uncommon. Some isolates of influenza A virus cause severe disease both in domestic poultry and, rarely, in humans. Occasionally, viruses are transmitted from wild aquatic birds to domestic poultry, and this may cause an outbreak or give rise to human influenza pandemics. Influenza A viruses are negative-sense, single-stranded, segmented RNA viruses. The several subtypes are labeled according to an H number (for the type of hemagglutinin) and an N number (for the type of neuraminidase). There are 18 different known H antigens (H1 to H18) and 11 different known N antigens (N1 to N11). H17N10 was isolated from fruit bats in 2012. H18N11 was discovered in a Peruvian bat in 2013. Each virus subtype has mutated into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Candida Albicans
''Candida albicans'' is an opportunistic pathogenic yeast that is a common member of the human gut flora. It can also survive outside the human body. It is detected in the gastrointestinal tract and mouth in 40–60% of healthy adults. It is usually a commensal organism, but it can become pathogenic in immunocompromised individuals under a variety of conditions. It is one of the few species of the genus '' Candida'' that causes the human infection candidiasis, which results from an overgrowth of the fungus. Candidiasis is, for example, often observed in HIV-infected patients. ''C. albicans'' is the most common fungal species isolated from biofilms either formed on (permanent) implanted medical devices or on human tissue. ''C. albicans'', ''C. tropicalis'', ''C. parapsilosis'', and ''C. glabrata'' are together responsible for 50–90% of all cases of candidiasis in humans. A mortality rate of 40% has been reported for patients with systemic candidiasis due to ''C. albicans' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitute 1% of all described fungal species. Yeasts are unicellular organisms that evolved from multicellular ancestors, with some species having the ability to develop multicellular characteristics by forming strings of connected budding cells known as pseudohyphae or false hyphae. Yeast sizes vary greatly, depending on species and environment, typically measuring 3–4 µm in diameter, although some yeasts can grow to 40 µm in size. Most yeasts reproduce asexually by mitosis, and many do so by the asymmetric division process known as budding. With their single-celled growth habit, yeasts can be contrasted with molds, which grow hyphae. Fungal species that can take both forms (depending on temperature or other conditions) a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alternative Complement Pathway
The alternative pathway is a type of cascade reaction of the complement system and is a component of the innate immune system, a natural defense against infections. The alternative pathway is one of three complement pathways that opsonize and kill pathogens. The pathway is triggered when the C3b protein directly binds a microbe. It can also be triggered by foreign materials and damaged tissues. Cascade This change in shape allows the binding of plasma protein Factor B, which allows Factor D to cleave Factor B into Ba and Bb. Bb remains bound to C3(H2O) to form C3(H2O)Bb. This complex is also known as a fluid-phase C3-convertase. This convertase, the alternative pathway C3-convertase, although only produced in small amounts, can cleave multiple C3 proteins into C3a and C3b. The complex is believed to be unstable until it binds properdin, a serum protein. The addition of properdin forms the complex C3bBbP, a stable compound which can bind an additional C3b to form alte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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