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91-472: See text Picornaviruses are a group of related nonenveloped RNA viruses which infect vertebrates including fish , mammals , and birds . They are viruses that represent a large family of small, positive-sense, single-stranded RNA viruses with a 30 nm icosahedral capsid . The viruses in this family can cause a range of diseases including the common cold , poliomyelitis , meningitis , hepatitis , and paralysis . Picornaviruses constitute

182-471: A flame test , sodium and its compounds glow yellow because the excited 3s electrons of sodium emit a photon when they fall from 3p to 3s; the wavelength of this photon corresponds to the D line at about 589.3 nm. Spin-orbit interactions involving the electron in the 3p orbital split the D line into two, at 589.0 and 589.6 nm; hyperfine structures involving both orbitals cause many more lines. Twenty isotopes of sodium are known, but only Na

273-443: A nucleus (enucleated) and those treated with actinomycin D (this antibiotic would inhibit viral replication if this occurred in the nucleus.) Translation takes place by -1 ribosomal frameshifting, viral initiation, and ribosomal skipping. The virus exits in host cell by lysis, and viroporins. Vertebrates serve as the natural hosts. Transmission routes are fecal-oral, contact, ingestion, and air-borne particles. Picornaviruses have

364-423: A phase-transfer catalyst . Sodium content of samples is determined by atomic absorption spectrophotometry or by potentiometry using ion-selective electrodes. Like the other alkali metals, sodium dissolves in ammonia and some amines to give deeply colored solutions; evaporation of these solutions leaves a shiny film of metallic sodium. The solutions contain the coordination complex [Na(NH 3 ) 6 ] , with

455-503: A raising agent , and sodablasting . Along with potassium, many important medicines have sodium added to improve their bioavailability ; though potassium is the better ion in most cases, sodium is chosen for its lower price and atomic weight. Sodium hydride is used as a base for various reactions (such as the aldol reaction ) in organic chemistry. Metallic sodium is used mainly for the production of sodium borohydride , sodium azide , indigo , and triphenylphosphine . A once-common use

546-492: A cid ". Secondly, the name derives from pico - , which designates a very small unit of measurement (equivalent to 10), combined with rna to describe this group of very small RNA viruses . The first animal virus discovered (1897) was the foot-and-mouth disease virus (FMDV). It is the prototypic member of the genus Aphthovirus in the Picornaviridae family. The plaque assay was developed using poliovirus ;

637-533: A compound of sodium with the Latin name of sodanum was used as a headache remedy. The name sodium is thought to originate from the Arabic suda , meaning headache, as the headache-alleviating properties of sodium carbonate or soda were well known in early times. Although sodium, sometimes called soda , had long been recognized in compounds, the metal itself was not isolated until 1807 by Sir Humphry Davy through

728-524: A corner of our 60 m room farthest away from the apparatus, we exploded 3 mg of sodium chlorate with milk sugar while observing the nonluminous flame before the slit. After a while, it glowed a bright yellow and showed a strong sodium line that disappeared only after 10 minutes. From the weight of the sodium salt and the volume of air in the room, we easily calculate that one part by weight of air could not contain more than 1/20 millionth weight of sodium. The Earth's crust contains 2.27% sodium, making it

819-549: A defined consensus sequence to which the initiation components bind, but no consensus sequence exists for the supporting stem, which suggests that only the structural stability of the CRE is important. VPg may also play an important role in specific recognition of viral genome by movement proteins (MP), which are nonstructural proteins encoded by many, if not all, plant viruses to enable their movement from one infected cell to neighboring cells. MP and VPg interact to provide specificity for

910-430: A factor in determining longevity of a virus on inanimate surfaces. Enveloped viruses possess great adaptability and can change in a short time in order to evade the immune system. Enveloped viruses can cause persistent infections . Vaccination against enveloped viruses can function by neutralizing the glycoprotein activity with antibodies. Eliminating the virus's ability to form an envelope—by removing or inactivating

1001-567: A high affinity for the sodium ion; derivatives of the alkalide Na are obtainable by the addition of cryptands to solutions of sodium in ammonia via disproportionation . Many organosodium compounds have been prepared. Because of the high polarity of the C-Na bonds, they behave like sources of carbanions (salts with organic anions ). Some well-known derivatives include sodium cyclopentadienide (NaC 5 H 5 ) and trityl sodium ((C 6 H 5 ) 3 CNa). Sodium naphthalene , Na [C 10 H 8 •] ,

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1092-415: A high neutron flux in the reactor. The high boiling point of sodium allows the reactor to operate at ambient (normal) pressure, but drawbacks include its opacity, which hinders visual maintenance, and its strongly reducing properties. Sodium will explode in contact with water, although it will only burn gently in air. Radioactive sodium-24 may be produced by neutron bombardment during operation, posing

1183-478: A messenger RNA. The viral particle binds to cell surface receptors. Cell surface receptors are characterized for each serotype of picornaviruses. For example, poliovirus receptor is glycoprotein CD155, which is special receptor for human and some other primate species. For this reason, poliovirus could not be made in many laboratories until transgenic mice having a CD155 receptor on their cell surfaces were developed in

1274-466: A nutrient for animals including humans. Sodium is an essential element for all animals and some plants. Sodium ions are the major cation in the extracellular fluid (ECF) and as such are the major contributor to the ECF osmotic pressure . Animal cells actively pump sodium ions out of the cells by means of the sodium–potassium pump , an enzyme complex embedded in the cell membrane , in order to maintain

1365-400: A protein shell known as the capsid, from the Latin capsa, meaning "box," in order to shield it from this hostile environment. Similar to how numerous bricks come together to form a wall, the capsid is made up of one or more distinct protein types that repeatedly repeat to form the whole capsid. This repetitive pattern creates a robust but rather flexible capsid. The nucleic acid inside the capsid

1456-454: A result, flaviviruses and pseudo typed retroviruses have a harder time infecting TAM-deficient DCs, albeit infection can be brought back by type I IFN antibodies. A TAM kinase inhibitor, meanwhile, prevents infection of wild-type DCs. TAM receptors, which are potential targets for therapy, are thereby activated by viruses to reduce type I IFN signaling. Glycoproteins on the surface of the envelope serve to identify and bind to receptor sites on

1547-888: A result, sodium usually forms ionic compounds involving the Na cation. Metallic sodium is generally less reactive than potassium and more reactive than lithium . Sodium metal is highly reducing, with the standard reduction potential for the Na /Na couple being −2.71 volts, though potassium and lithium have even more negative potentials. Sodium compounds are of immense commercial importance, being particularly central to industries producing glass , paper , soap , and textiles . The most important sodium compounds are table salt (Na Cl ), soda ash (Na 2 CO 3 ), baking soda (Na HCO 3 ), caustic soda (NaOH), sodium nitrate (Na NO 3 ), di- and tri- sodium phosphates , sodium thiosulfate (Na 2 S 2 O 3 ·5H 2 O), and borax (Na 2 B 4 O 7 ·10H 2 O). In compounds, sodium

1638-495: A result, the committee has established Adequate Intake (AI) levels instead, as follows. The sodium AI for infants of 0–6 months is established at 110 mg/day, 7–12 months: 370 mg/day; for children 1–3 years: 800 mg/day, 4–8 years: 1,000 mg/day; for adolescents: 9–13 years – 1,200 mg/day, 14–18 years 1,500 mg/day; for adults regardless of their age or sex: 1,500 mg/day. Sodium chloride ( NaCl ) contains approximately 39.34% of elemental sodium ( Na )

1729-421: A roughly ten-times higher concentration of sodium ions outside the cell than inside. In nerve cells , the sudden flow of sodium ions into the cell through voltage-gated sodium channels enables transmission of a nerve impulse in a process called the action potential . Sodium at standard temperature and pressure is a soft silvery metal that combines with oxygen in the air, forming sodium oxides . Bulk sodium

1820-461: A slight radiation hazard; the radioactivity stops within a few days after removal from the reactor. If a reactor needs to be shut down frequently, NaK is used. Because NaK is a liquid at room temperature, the coolant does not solidify in the pipes. In this case, the pyrophoricity of potassium requires extra precautions to prevent and detect leaks. Another heat transfer application is poppet valves in high-performance internal combustion engines;

1911-502: A small 22– to 25-amino acid-long viral protein linked to the VPg to initiate polymerase activity, where the primer is covalently bound to the 5' end of the RNA template. The uridylylation occurs at a tyrosine residue at the third position of the VPg. A CRE, which is a RNA stem loop structure, serves as a template for the uridylylation of VPg, resulting in the synthesis of VPgpUpUOH. Mutations within

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2002-408: A strong reducing agent, forms upon mixing Na and naphthalene in ethereal solutions. Sodium forms alloys with many metals, such as potassium, calcium , lead , and the group 11 and 12 elements. Sodium and potassium form KNa 2 and NaK . NaK is 40–90% potassium and it is liquid at ambient temperature . It is an excellent thermal and electrical conductor. Sodium-calcium alloys are by-products of

2093-440: A structural protein—or to bud has been studied as a method for producing viruses incapable of replication. The following are some examples of enveloped virus species: The following are some examples of viruses without envelopes: Sodium Sodium is a chemical element ; it has symbol   Na (from Neo-Latin natrium ) and atomic number  11. It is a soft, silvery-white, highly reactive metal . Sodium

2184-400: A viral protein ( VPg ) covalently linked to 5' end of their genomes instead of 7-methylguanosine cap like cellular mRNAs. Virus RNA polymerases use VPg as primer. VPg as primer uses both positive- and negative-strand RNA synthesis. Picornavirus replication is initiated by the uridylylation of VPg. It is uridylylated at the hydroxyl group of a tyrosine residue. A VPg primer mechanism is used by

2275-488: A virus buds often dies or is weakened, and sheds more viral particles for an extended period. The lipid bilayer envelope of these viruses is relatively sensitive to desiccation , heat, and amphiphiles such as soap and detergents , therefore these viruses are easier to sterilize than non-enveloped viruses, have limited survival outside host environments, and typically must transfer directly from host to host. Viral envelope persistence, whether it be enveloped or naked, are

2366-461: Is an alkali metal , being in group 1 of the periodic table. Its only stable isotope is Na. The free metal does not occur in nature and must be prepared from compounds. Sodium is the sixth most abundant element in the Earth's crust and exists in numerous minerals such as feldspars , sodalite , and halite (NaCl). Many salts of sodium are highly water-soluble: sodium ions have been leached by

2457-422: Is appropriately protected by its modest size and physical difficulty in opening it. The nucleocapsid of the virion is made up of the nucleic acid and the capsid. Remember that the genomes of most viruses are very small. Genes code for instructions to make proteins, so small genomes cannot code for many proteins. Therefore, the virion capsid consists of one or only a few proteins that repeat over and over  to form

2548-463: Is caused by the viral fusion protein . Many enveloped viruses only have one protein visible on the surface of the particle, which is required for both mediating adhesion to the cell surface and for the subsequent membrane fusion process. To create potentially protective vaccines for human pathogenic enveloped viruses for which there is currently no vaccine, it is essential to comprehend how antibodies interact with viral envelope proteins, particularly with

2639-402: Is cleaved to give the different capsid components. The icosahedral capsid is said to have a triangulation number of 3, this means that in the icosahedral structure each of the 60 triangles that make up the capsid are split into three little triangles with a subunit on the corner. Many picornaviruses have a deep cleft formed by around each of the 12 vertices of icosahedrons. The outer surface of

2730-457: Is dissolved in ammonia solution, it can be used to reduce alkynes to trans- alkenes . Lasers emitting light at the sodium D line are used to create artificial laser guide stars that assist in the adaptive optics for land-based visible-light telescopes. Liquid sodium is used as a heat transfer fluid in sodium-cooled fast reactors because it has the high thermal conductivity and low neutron absorption cross section required to achieve

2821-480: Is first cut to yield P1, P2, and P3. P1 becomes myristylated at the N terminus before being cleaved to VP0, VP3, and VP1, the proteins that will form procapsids; VP0 will later be cleaved to produce VP2 and VP4. Other cleavage products include 3B (VPg), 2C (an ATPase), and 3D (the RNA polymerase). Genomic RNAs of picornaviruses possess multiple RNA elements, and they are required for both negative- and positive-strand RNA synthesis. The cis-acting replication element (CRE)

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2912-429: Is formed using viral RNA-dependent RNA polymerase. Translation by host-cell ribosomes is not initiated by a 5' G cap as usual, but rather is initiated by an internal ribosome entry site. The viral life cycle is very rapid, with the whole process of replication being completed on average within 8 hours. As little as 30 minutes after initial infection, though, cell protein synthesis declines to almost zero output – essentially

3003-413: Is found at both ends of the picornavirus genome. The 5' UTR is usually longer, being around 500–1200 nucleotides (nt) in length, compared to that of the 3' UTR, which is around 30–650 nt. The 5' UTR is thought to be important in translation, and the 3' in negative-strand synthesis; however, the 5' end may also have a role to play in virulence of the virus. The rest of the genome encodes structural proteins at

3094-456: Is less electropositive than sodium, no calcium will be deposited at the cathode. This method is less expensive than the previous Castner process (the electrolysis of sodium hydroxide ). If sodium of high purity is required, it can be distilled once or several times. The market for sodium is volatile due to the difficulty in its storage and shipping; it must be stored under a dry inert gas atmosphere or anhydrous mineral oil to prevent

3185-405: Is not necessary for negative-strand synthesis, but is important element for positive–strand synthesis. Additionally, the 5' end NCR that contains secondary structural elements is required for RNA replication and poliovirus translation initiation. Internal ribosome entry sites are RNA structures that allow cap-independent initiation of translation, and are able to initiate translation in the middle of

3276-406: Is required for efficient negative-strand RNA synthesis, especially when UTP concentrations are limiting. The VPgpUpUOH primer is transferred to the 3’ end of the RNA template for elongation, which can continue by addition of nucleotide bases by RdRp. Partial crystal structures for VPgs of foot and mouth disease virus and coxsackie virus B3 suggest that there may be two sites on the viral polymerase for

3367-467: Is required for replication. The stem-loop-structure that contains the CRE is independent of position, but changes with location between virus types when it has been identified. Also, the 3' end elements of viral RNA are significant and efficient for RNA replication of picornaviruses. The 3' end of picornavirus contains a poly(A) tract, which is required for infectivity. RNA synthesis, though, is hypothesized to occur in this region. The 3' end NCR of poliovirus

3458-531: Is seen in any whose surfaces are cool enough for sodium to exist in atomic form (rather than ionised). This corresponds to stars of roughly F-type and cooler. Many other stars appear to have a sodium absorption line, but this is actually caused by gas in the foreground interstellar medium . The two can be distinguished via high-resolution spectroscopy, because interstellar lines are much narrower than those broadened by stellar rotation . Sodium has also been detected in numerous Solar System environments, including

3549-462: Is stable. Na is created in the carbon-burning process in stars by fusing two carbon atoms together; this requires temperatures above 600 megakelvins and a star of at least three solar masses. Two radioactive , cosmogenic isotopes are the byproduct of cosmic ray spallation : Na has a half-life of 2.6 years and Na, a half-life of 15 hours; all other isotopes have a half-life of less than one minute. Two nuclear isomers have been discovered,

3640-488: Is the lower temperature of the nose. Enteroviruses are stable under acidic conditions, thus they are able to survive exposure to gastric acid . In contrast, rhinoviruses are acid-labile (inactivated or destroyed by low pH conditions), so rhinovirus infections are restricted to the nose and throat. These genera are recognized: Viral envelope Numerous human pathogenic viruses in circulation are encased in lipid bilayers , and they infect their target cells by causing

3731-549: Is the principal source of sodium ( Na ) in the diet, and is used as seasoning and preservative in such commodities as pickled preserves and jerky ; for Americans, most sodium chloride comes from processed foods . Other sources of sodium are its natural occurrence in food and such food additives as monosodium glutamate (MSG), sodium nitrite , sodium saccharin, baking soda (sodium bicarbonate), and sodium benzoate . The U.S. Institute of Medicine set its tolerable upper intake level for sodium at 2.3 grams per day, but

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3822-622: Is to melt them together and another is to deposit sodium electrolytically on molten lead cathodes. NaPb 3 , NaPb, Na 9 Pb 4 , Na 5 Pb 2 , and Na 15 Pb 4 are some of the known sodium-lead alloys. Sodium also forms alloys with gold (NaAu 2 ) and silver (NaAg 2 ). Group 12 metals ( zinc , cadmium and mercury ) are known to make alloys with sodium. NaZn 13 and NaCd 2 are alloys of zinc and cadmium. Sodium and mercury form NaHg, NaHg 4 , NaHg 2 , Na 3 Hg 2 , and Na 3 Hg. Because of its importance in human health, salt has long been an important commodity. In medieval Europe,

3913-628: Is usually ionically bonded to water and anions and is viewed as a hard Lewis acid . Most soaps are sodium salts of fatty acids . Sodium soaps have a higher melting temperature (and seem "harder") than potassium soaps. Like all the alkali metals , sodium reacts exothermically with water. The reaction produces caustic soda ( sodium hydroxide ) and flammable hydrogen gas. When burned in air, it forms primarily sodium peroxide with some sodium oxide . Sodium tends to form water-soluble compounds, such as halides , sulfates , nitrates , carboxylates and carbonates . The main aqueous species are

4004-469: Is usually stored in oil or an inert gas. Sodium metal can be easily cut with a knife. It is a good conductor of electricity and heat. Due to having low atomic mass and large atomic radius, sodium is third-least dense of all elemental metals and is one of only three metals that can float on water, the other two being lithium and potassium. The melting (98 °C) and boiling (883 °C) points of sodium are lower than those of lithium but higher than those of

4095-595: The Sun . The line was first studied in 1814 by Joseph von Fraunhofer during his investigation of the lines in the solar spectrum, now known as the Fraunhofer lines . Fraunhofer named it the "D" line, although it is now known to actually be a group of closely spaced lines split by a fine and hyperfine structure . The strength of the D ;line allows its detection in many other astronomical environments. In stars, it

4186-472: The electrolysis of sodium hydroxide . In 1809, the German physicist and chemist Ludwig Wilhelm Gilbert proposed the names Natronium for Humphry Davy's "sodium" and Kalium for Davy's "potassium". The chemical abbreviation for sodium was first published in 1814 by Jöns Jakob Berzelius in his system of atomic symbols, and is an abbreviation of the element's Neo-Latin name natrium , which refers to

4277-467: The exospheres of Mercury and the Moon , and numerous other bodies. Some comets have a sodium tail , which was first detected in observations of Comet Hale–Bopp in 1997. Sodium has even been detected in the atmospheres of some extrasolar planets via transit spectroscopy . Employed in rather specialized applications, about 100,000 tonnes of metallic sodium are produced annually. Metallic sodium

4368-522: The family Picornaviridae , order Picornavirales , and realm Riboviria . There are 158 species in this family, assigned to 68 genera. Notable examples are genera Enterovirus (including Rhinovirus and Poliovirus ), Aphthovirus , Cardiovirus , and Hepatovirus . The name "picornavirus" has a dual etymology . Firstly, the name derives from picorna - which is an acronym for " p oliovirus, i nsensitivity to ether , c oxsackievirus , o rphan virus , r hinovirus, and ribo n ucleic

4459-541: The ligands Gas6 and Protein S . The phospholipid phosphatidylserine may be seen on the membranes of several enveloped viruses, which they employ to bind Gas6 and Protein S to activate TAM receptors. Ligand-coated viruses stimulate type I IFN signaling, activate TAM receptors on dendritic cells (DCs), and suppress type II interferon signaling to circumvent host defenses and advance infection.TAM-deficient DCs exhibit type I IFN responses that are more pronounced than those of wild-type cells in response to viral exposure. As

4550-558: The sixth most abundant element on Earth and the fourth most abundant metal, behind aluminium , iron , calcium , and magnesium and ahead of potassium. Sodium's estimated oceanic abundance is 10.8 grams per liter. Because of its high reactivity, it is never found as a pure element. It is found in many minerals, some very soluble, such as halite and natron , others much less soluble, such as amphibole and zeolite . The insolubility of certain sodium minerals such as cryolite and feldspar arises from their polymeric anions, which in

4641-445: The viral core (capsid). For a very long time, it was thought that the spike proteins, which are necessary for infectivity, were directly incorporated into the viral core through their cytoplasmic domains. Recent research suggests that while such direct interactions may be what causes the budding of alphaviruses, this may not be the case for retroviruses and negative strand RNA viruses . These viruses can form bud particles even in

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4732-402: The 1990s. These animals can be infected and used for studies of replication and pathogenesis. Binding causes a conformational change in the viral capsid proteins, and myristic acid is released. The acid forms a pore in the cell membrane through which RNA is injected. Once inside the cell, the RNA uncoats and the (+) strand RNA genome is replicated through a double-stranded RNA intermediate that

4823-406: The 3' end. Tyrosine as a –OH source for covalently linked to 5' end of RNA. The genome is not segmented and positive-sense (the same sense as mammalian mRNA, being read 5' to 3'). Unlike mammalian mRNA , picornaviruses do not have a 5' cap , but a virally encoded protein known as VPg . However, like mammalian mRNA, the genome does have a poly(A) tail at the 3' end. An untranslated region (UTR)

4914-399: The 5' end and nonstructural proteins at the 3' end in a single polyprotein. The polyprotein is organised as: L-1ABCD-2ABC-3ABCD with each letter representing a protein, but variations to this layout exist. The 1A, 1B, 1C, and 1D proteins are the capsid proteins VP4, VP2, VP3, and VP1, respectively. Virus-coded proteases perform the cleavages, some of which are intramolecular. The polyprotein

5005-535: The CRE-RNA structure prevent VPg uridylylation, and mutations within the VPg sequence can severely diminish RdRp catalytic activity. While the tyrosine hydroxyl of VPg can prime negative-strand RNA synthesis in a CRE- and VPgpUpUOH-independent manner, CRE-dependent VPgpUpUOH synthesis is absolutely required for positive-strand RNA synthesis. CRE-dependent VPg uridylylation lowers the K m¬ of UTP required for viral RNA replication and CRE-dependent VPgpUpUOH synthesis, and

5096-523: The Egyptian natron , a natural mineral salt mainly consisting of hydrated sodium carbonate. Natron historically had several important industrial and household uses, later eclipsed by other sodium compounds. Sodium imparts an intense yellow color to flames. As early as 1860, Kirchhoff and Bunsen noted the high sensitivity of a sodium flame test , and stated in Annalen der Physik und Chemie : In

5187-617: The absence of spike proteins by relying only on viral core components. The spike proteins can occasionally be produced as virus-like particles without the viral core. Therefore, optimal budding and release may be dependent on a coordinated "push-and-pull" action between core and spike, where oligomerization of both components is essential. They may help viruses avoid the host immune system . TAM receptor tyrosine kinases increase phagocytic clearance of apoptotic cells and inhibit immunological responses brought on by Toll-like receptors and type I interferons (IFNs) when they are activated by

5278-469: The action of water from the Earth's minerals over eons, and thus sodium and chlorine are the most common dissolved elements by weight in the oceans. Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide . Among many other useful sodium compounds, sodium hydroxide ( lye ) is used in soap manufacture , and sodium chloride ( edible salt ) is a de-icing agent and

5369-689: The aquo complexes [Na(H 2 O) n ] , where n = 4–8; with n = 6 indicated from X-ray diffraction data and computer simulations. Direct precipitation of sodium salts from aqueous solutions is rare because sodium salts typically have a high affinity for water. An exception is sodium bismuthate (NaBiO 3 ), which is insoluble in cold water and decomposes in hot water. Because of the high solubility of its compounds, sodium salts are usually isolated as solids by evaporation or by precipitation with an organic antisolvent, such as ethanol ; for example, only 0.35 g/L of sodium chloride will dissolve in ethanol. A crown ether such as 15-crown-5 may be used as

5460-715: The average person in the United States consumes 3.4 grams per day. The American Heart Association recommends no more than 1.5 g of sodium per day. The Committee to Review the Dietary Reference Intakes for Sodium and Potassium, which is part of the National Academies of Sciences, Engineering, and Medicine, has determined that there isn't enough evidence from research studies to establish Estimated Average Requirement (EAR) and Recommended Dietary Allowance (RDA) values for sodium. As

5551-415: The capsid is composed of regions of VP1, VP2, and VP3. Around each of the vertices is a canyon lined with the C termini of VP1 and VP3. The interior surface of the capsid is composed of VP4 and the N termini of VP1. J. Esposito and Frederick A. Murphy demonstrates cleft structure referred to as canyons, using X-ray crystallography and cryoelectron microscopy. Depending on the type and degree of dehydration,

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5642-423: The case of feldspar is a polysilicate. In the universe, sodium is the 15th most abundant element with a 20,000 parts-per-billion abundance, making sodium 0.002% of the total atoms in the universe. Atomic sodium has a very strong spectral line in the yellow-orange part of the spectrum (the same line as is used in sodium-vapour street lights ). This appears as an absorption line in many types of stars, including

5733-434: The discovery of viral replication in culture was also with poliovirus in 1949. This was the first time that infectious virus had been produced in cultured cells. Polyprotein synthesis , internal ribosome entry sites , and uncapped mRNA were all discovered by studying poliovirus infected cells, and a poliovirus clone was the first infectious DNA clone made of an RNA virus in animals. Along with rhinovirus , poliovirus

5824-431: The electrolytic production of sodium from a binary salt mixture of NaCl-CaCl 2 and ternary mixture NaCl-CaCl 2 -BaCl 2 . Calcium is only partially miscible with sodium, and the 1–2% of it dissolved in the sodium obtained from said mixtures can be precipitated by cooling to 120 °C and filtering. In a liquid state, sodium is completely miscible with lead. There are several methods to make sodium-lead alloys. One

5915-497: The expression of cell surface proteins implicated in adaptive immunity. Being made up mostly of host membrane, the viral envelope can also have the proteins associated with the host cell within their membrane after budding. Many enveloped viruses mature by budding at the plasma membrane, which allows them to be discharged from infected cells. During this procedure, viral transmembrane proteins, also known as spike proteins , are integrated into membrane vesicles containing components of

6006-420: The formation of a surface layer of sodium oxide or sodium superoxide . Though metallic sodium has some important uses, the major applications for sodium use compounds; millions of tons of sodium chloride , hydroxide , and carbonate are produced annually. Sodium chloride is extensively used for anti-icing and de-icing and as a preservative; examples of the uses of sodium bicarbonate include baking, as

6097-465: The fusion protein to the cell surface but may also happen extracellularly. So far, structural studies have revealed two kinds of viral fusion proteins. These proteins are believed to catalyze the same mechanism in both situations, resulting in the fusing of two bilayers. In other words, these proteins operate as enzymes, which while having various structural variations catalyze the same chemical reaction. The envelopes are typically derived from portions of

6188-475: The fusion protein, and how antibodies neutralize viruses. Enveloped viruses enter cells by joining a cellular membrane to their lipid bilayer membrane. Priming by proteolytic processing, either of the fusion protein or of a companion protein, is necessary for the majority of viral fusion proteins. The priming stage then gets the fusion protein ready for triggering by the processes that go along with attachment and uptake, which frequently happens during transport of

6279-430: The genetic material alone is infectious; although substantially less virulent than if contained within the viral particle, the RNA can have increased infectivity when transfected into cells. The genome RNA is unusual because it has a protein on the 5' end that is used as a primer for transcription by RNA polymerase . This primer is called VPg genome, and it ranges between 2 and 3 kb. VPg contain tyrosine residue at

6370-435: The heavier alkali metals potassium, rubidium, and caesium, following periodic trends down the group. These properties change dramatically at elevated pressures: at 1.5  Mbar , the color changes from silvery metallic to black; at 1.9 Mbar the material becomes transparent with a red color; and at 3 Mbar, sodium is a clear and transparent solid. All of these high-pressure allotropes are insulators and electrides . In

6461-498: The host cell membranes ( phospholipids and proteins), but include some viral glycoproteins . One of the main parts of human pathogenic viruses is glycoprotein. They have been shown to play significant roles in immunity and infection. Viral glycoproteins, a new class of cellular inhibitory proteins has been discovered. These include the E3 ubiquitin ligases of the membrane-associated RING-CH (MARCH) family, which among other things, inhibits

6552-419: The host cell. There are three main types of viral glycoproteins: Envelope proteins, membrane proteins, and spike proteins (E, M, and S). The viral envelope then fuses with the host's membrane, allowing the capsid and viral genome to enter and infect the host. All enveloped viruses also have a capsid , another protein layer, between the envelope and the genome. The virus wraps its delicate nucleic acid with

6643-441: The host's membrane. The particular set of viral proteins are engaged in a series of structural changes. When these changes are set/finished, there is then and only then, fusion with the host membrane. These glycoproteins mediate the interaction between virion and host cell, typically initiating the fusion between the viral envelope and the host's cellular membrane. In some cases, the virus with an envelope will form an endosome within

6734-517: The longer-lived one being Na with a half-life of around 20.2 milliseconds. Acute neutron radiation, as from a nuclear criticality accident , converts some of the stable Na in human blood to Na; the neutron radiation dosage of a victim can be calculated by measuring the concentration of Na relative to Na. Sodium atoms have 11 electrons, one more than the stable configuration of the noble gas neon . The first and second ionization energies are 495.8 kJ/mol and 4562 kJ/mol, respectively. As

6825-430: The macromolecular synthesis of cell proteins is shut off. Over the next 1–2 hours, a loss of margination of chromatin and homogeneity occurs in the nucleus, before the viral proteins start to be synthesized and a vacuole appears in the cytoplasm close to the nucleus that gradually starts to spread as the time after infection reaches around 3 hours. After this time, the cell plasma membrane becomes permeable; at 4–6 hours,

6916-466: The need for large quantities of sodium. A related process based on the reduction of sodium hydroxide was developed in 1886. Sodium is now produced commercially through the electrolysis of molten sodium chloride (common salt), based on a process patented in 1924. This is done in a Downs cell in which the NaCl is mixed with calcium chloride to lower the melting point below 700 °C. As calcium

7007-466: The picornavirus (entero- aphtho-, and others), additional virus groups (poty-, como-, calici-, and others) and picornavirus-like (coronavirus, notavirus, etc.) supergroup of RNA viruses. The mechanism has been best studied for the enteroviruses (which include many human pathogens, such as poliovirus and coxsackie viruses ), as well as for the aphthovirus, an animal pathogen causing foot-and-mouth disease. In this group, primer-dependent RNA synthesis uses

7098-468: The picornaviruses. Mechanisms for uridylylation and priming may be quite different in all of these groups. VPg uridylylation may include the use of precursor proteins, allowing for the determination of a possible mechanism for the location of the diuridylylated, VPg-containing precursor at the 3' end of positive- or negative-strand RNA for production of full-length RNA. Determinants of VPg uridylylation efficiency suggest formation and/or collapse or release of

7189-441: The positive charge counterbalanced by electrons as anions ; cryptands permit the isolation of these complexes as crystalline solids. Sodium forms complexes with crown ethers, cryptands and other ligands. For example, 15-crown-5 has a high affinity for sodium because the cavity size of 15-crown-5 is 1.7–2.2 Å, which is enough to fit the sodium ion (1.9 Å). Cryptands, like crown ethers and other ionophores , also have

7280-456: The pressure increases. By itself or with potassium , sodium is a desiccant ; it gives an intense blue coloration with benzophenone when the desiccate is dry. In organic synthesis , sodium is used in various reactions such as the Birch reduction , and the sodium fusion test is conducted to qualitatively analyse compounds. Sodium reacts with alcohols and gives alkoxides , and when sodium

7371-464: The small VPgs of the picornaviruses. NMR solution structures of poliovirus VPg and VPgpU show that uridylylation stabilizes the structure of the VPg, which is otherwise quite flexible in solution. The second site may be used for uridylylation,v after which the VPgpU can initiate RNA synthesis. The VPg primers of caliciviruses, whose structures are only beginning to be revealed, are much larger than those of

7462-431: The structure. The viral nucleic acid  would be physically too large to fit inside the capsid if it consisted of more than  a few proteins. The capsid, having a focused role of protecting the genome in addition to immune recognition evasion. The viral capsid is known for its protection of RNA before it is inserted into the host cell, unlike the viral envelope which protects the protein capsid. The cell from which

7553-436: The transport of viral RNA from cell to cell. To fulfill energy requirements, MP also interacts with P10, which is a cellular ATPase. Picornaviruses cause a range of diseases. Enteroviruses of the picornavirus family infect the enteric tract, which is reflected in their name. Rhinoviruses infect primarily the nose and the throat . Enteroviruses replicate at 37 °C, whereas rhinoviruses grow better at 33 °C, as this

7644-428: The uridylylated product as the rate-limiting step in vitro depending upon the VPg donor employed. Precursor proteins also have an effect on VPg-CRE specificity and stability. The upper RNA stem loop, to which VPg binds, has a significant impact on both retention, and recruitment, of VPg and Pol. The stem loop of CRE will partially unwind, allowing the precursor components to bind and recruit VPg and Pol4. The CRE loop has

7735-476: The valve stems are partially filled with sodium and work as a heat pipe to cool the valves. In humans, sodium is an essential mineral that regulates blood volume, blood pressure, osmotic equilibrium and pH . The minimum physiological requirement for sodium is estimated to range from about 120 milligrams per day in newborns to 500 milligrams per day over the age of 10. Sodium chloride , also known as edible salt or table salt (chemical formula NaCl ),

7826-460: The viral envelope and cell membrane to fuse. Although there are effective vaccines against some of these viruses, there is no preventative or curative medicine for the majority of them. In most cases, the known vaccines operate by inducing antibodies that prevent the pathogen from entering cells. This happens in the case of enveloped viruses when the antibodies bind to the viral envelope proteins. The membrane fusion event that triggers viral entrance

7917-537: The viral particle is around 30–32 nm in diameter. The viral genome is around 2500 nm in length, so it is tightly packaged within the capsid along with substances such as sodium ions to balance the negative charges on the RNA caused by the phosphate groups. Picornaviruses are classed under Baltimore's viral classification system as group IV viruses, as they contain a single-stranded, positive-sense RNA genome . Their genome ranges between 6.7 and 10.1 ( kilobases ) in length. Like most positive-sense RNA genomes,

8008-433: The virus particles assemble, and can sometimes be seen in the cytoplasm. Around 8 hours, the cell is effectively dead, and lyses to release the viral particles. Experimental data from single-step growth curve-like experiments have allowed observation of the replication of the picornaviruses in great detail. The whole of replication occurs within the host-cell cytoplasm and infection can even happen in cells that do not contain

8099-519: Was first produced commercially in the late nineteenth century by carbothermal reduction of sodium carbonate at 1100 °C, as the first step of the Deville process for the production of aluminium: The high demand for aluminium created the need for the production of sodium. The introduction of the Hall–Héroult process for the production of aluminium by electrolysing a molten salt bath ended

8190-553: Was the first animal virus to have its structure determined by x-ray crystallography . RNA dependent RNA polymerase was discovered in Mengovirus , a genus of picornaviruses. Picornaviruses are nonenveloped, with an icosahedral capsid . The capsid is an arrangement of 60 protomers in a tightly packed icosahedral structure. Each protomer consists of four polypeptides known as VP (viral protein) 1, 2, 3 and 4. VP2 and VP4 polypeptides originate from one protomer known as VP0 that

8281-554: Was the making of tetraethyllead and titanium metal; because of the move away from TEL and new titanium production methods, the production of sodium declined after 1970. Sodium is also used as an alloying metal, an anti-scaling agent , and as a reducing agent for metals when other materials are ineffective. Note the free element is not used as a scaling agent, ions in the water are exchanged for sodium ions. Sodium plasma ("vapor") lamps are often used for street lighting in cities, shedding light that ranges from yellow-orange to peach as

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