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Buoyant Density Centrifugation
Buoyant density centrifugation (also isopycnic centrifugation or equilibrium density-gradient centrifugation) uses the concept of buoyancy to separate molecules in solution by their differences in density. Implementation Historically a cesium chloride (CsCl) solution was often used, but more commonly used density gradients are sucrose or Percoll. This application requires a solution with high density and yet relatively low viscosity, and CsCl suits it because of its high solubility in water, high density owing to the large mass of Cs, as well as low viscosity and high stability of CsCl solutions. The sample is put on top of the solution, and then the tube is spun at a very high speed for an extended time, at times lasting days. The CsCl molecules become densely packed toward the bottom, so a continuous gradient of layers of different densities (and CsCl concentrations) form. Since the original solution was approximately the same density, they go to a level where their density an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canines Parvovirus
Canine may refer to: Zoology and anatomy * Animals of the family Canidae, more specifically the subfamily Caninae, which includes dogs, wolves, foxes, jackals and coyotes ** ''Canis'', a genus that includes dogs, wolves, coyotes, and jackals ** Dog, the domestic dog * Canine tooth, in mammalian oral anatomy People with the surname * Henry Canine (), American football coach * Ralph Canine (1895–1969), founding director of the United States National Security Agency Other uses * Canine, a fictional dog in the ''Glenn Martin, DDS'' animated television series * Canine Hills, Antarctic landform in the Bowers Mountains, Victoria Land See also * K9 (other) * Kanine (other) * Canina (other) * Cani (other) * List of canids Canidae is a family of mammals in the order Carnivora, which includes domestic dogs, wolves, coyotes, foxes, jackals, dingoes, and many other extant and extinct dog-like mammals. A member of this family is called a canid; all ext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoyancy
Buoyancy (), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus, the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and (as explained by Archimedes' principle) is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the Displacement (fluid), displaced fluid. For this reason, an object with average density greater than the surrounding fluid tends to sink because its weight is greater than the weight of the fluid it displaces. If the objec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cesium Chloride
Caesium chloride or cesium chloride is the inorganic compound with the formula Cs Cl. This colorless salt is an important source of caesium ions in a variety of niche applications. Its crystal structure forms a major structural type where each caesium ion is coordinated by 8 chloride ions. Caesium chloride dissolves in water. CsCl changes to NaCl structure on heating. Caesium chloride occurs naturally as impurities in carnallite (up to 0.002%), sylvite and kainite. Less than 20 tonnes of CsCl is produced annually worldwide, mostly from a caesium-bearing mineral pollucite. Caesium chloride is widely used in isopycnic centrifugation for separating various types of DNA. It is a reagent in analytical chemistry, where it is used to identify ions by the color and morphology of the precipitate. When enriched in radioisotopes, such as 137CsCl or 131CsCl, caesium chloride is used in nuclear medicine applications such as treatment of cancer and diagnosis of myocardial infarction. Another f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sucrose
Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula . For human consumption, sucrose is extracted and refined from either sugarcane or sugar beet. Sugar mills – typically located in tropical regions near where sugarcane is grown – crush the cane and produce raw sugar which is shipped to other factories for refining into pure sucrose. Sugar beet factories are located in temperate climates where the beet is grown, and process the beets directly into refined sugar. The Sugar refinery, sugar-refining process involves washing the raw sugar crystals before dissolving them into a sugar syrup which is filtered and then passed over carbon to remove any residual colour. The sugar syrup is then concentrated by boiling under a vacuum and crystallized as the final purification process to produce crystals of pure sucrose that are clear, odorless, and sweet. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Percoll
Percoll is a reagent consisting of colloidal silica particles used in cell biology and other laboratory settings. It was first formulated by Pertoft and colleagues, and commercialized by Pharmacia Fine Chemicals. Percoll is used for the isolation of cells, organelles, or viruses by density centrifugation. Percoll was developed from previously reported uses of colloidal silica nanoparticles coated with polysaccharides or polymers for rate zonal, isopycnic, or equilibrium centrifugal separations. Percoll itself specifically consists of polydisperse silica nanoparticles 15–30 nm diameter (23% w/w in water) which have been coated with polyvinylpyrrolidone (PVP). Percoll is well suited for density gradient experiments because it possesses a low viscosity compared to alternatives, a low osmolarity, and no toxicity towards cells and their constituents. Percoll is a registered trademark of Cytiva. Characteristics Percoll does not notably diffuse over time, resulting in the f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CsCl Density Gradient Centrifugation
Caesium chloride or cesium chloride is the inorganic compound with the formula Cs Cl. This colorless salt is an important source of caesium ions in a variety of niche applications. Its crystal structure forms a major structural type where each caesium ion is coordinated by 8 chloride ions. Caesium chloride dissolves in water. CsCl changes to NaCl structure on heating. Caesium chloride occurs naturally as impurities in carnallite (up to 0.002%), sylvite and kainite. Less than 20 tonnes of CsCl is produced annually worldwide, mostly from a caesium-bearing mineral pollucite. Caesium chloride is widely used in isopycnic centrifugation for separating various types of DNA. It is a reagent in analytical chemistry, where it is used to identify ions by the color and morphology of the precipitate. When enriched in radioisotopes, such as 137CsCl or 131CsCl, caesium chloride is used in nuclear medicine applications such as treatment of cancer and diagnosis of myocardial infarction. Another f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GC Content
In molecular biology and genetics, GC-content (or guanine-cytosine content) is the percentage of nitrogenous bases in a DNA or RNA molecule that are either guanine (G) or cytosine (C). This measure indicates the proportion of G and C bases out of an implied four total bases, also including adenine and thymine in DNA and adenine and uracil in RNA. GC-content may be given for a certain fragment of DNA or RNA or for an entire genome. When it refers to a fragment, it may denote the GC-content of an individual gene or section of a gene (domain), a group of genes or gene clusters, a non-coding region, or a synthetic oligonucleotide such as a primer. Structure Qualitatively, guanine (G) and cytosine (C) undergo a specific hydrogen bonding with each other, whereas adenine (A) bonds specifically with thymine (T) in DNA and with uracil (U) in RNA. Quantitatively, each GC base pair is held together by three hydrogen bonds, while AT and AU base pairs are held together by two hydrogen bon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellite DNA
Satellite DNA consists of very large arrays of tandem repeat, tandemly repeating, non-coding DNA. Satellite DNA is the main component of functional centromeres, and form the main structural constituent of heterochromatin. The name "satellite DNA" refers to the phenomenon that repetitions of a short DNA sequence tend to produce a different frequency of the bases adenine, cytosine, guanine, and thymine, and thus have a different density from bulk DNA such that they form a second or "satellite" band(s) when genomic DNA is separated along a cesium chloride density gradient using buoyant density centrifugation#DNA separation, buoyant density centrifugation. Sequences with a greater ratio of A+T display a lower density while those with a greater ratio of G+C display a higher density than the bulk of genomic DNA. Some repetitive sequences are ~50% G+C/A+T and thus have buoyant densities the same as bulk genomic DNA. These satellites are called "cryptic" satellites because they form a band ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isopycnic
An isopycnic surface is a surface of constant density inside a fluid. Isopycnic surfaces contrast with isobaric or isothermal surfaces, which describe surfaces of constant pressure and constant temperature respectively. Isopycnic surfaces are sometimes referred to as "iso-density" surfaces, although this is strictly incorrect. Isopycnic typically describes surfaces, not processes. Unless there is a flux of mass into or out of a control volume, a process which occurs at a constant density also occurs at a constant volume and is called an isochoric process and not an isopycnic process. The term "isopycnic" is commonly encountered in the fluid dynamics of compressible fluids, such as in meteorology and geophysical fluid dynamics, astrophysics, or the fluid dynamics of explosions or high Mach number flows.It may also be applied to other situations where a continuous medium has smoothly varying density, such as in the case of an inhomogeneous colloidal suspension. In general isopycni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellite DNA
Satellite DNA consists of very large arrays of tandem repeat, tandemly repeating, non-coding DNA. Satellite DNA is the main component of functional centromeres, and form the main structural constituent of heterochromatin. The name "satellite DNA" refers to the phenomenon that repetitions of a short DNA sequence tend to produce a different frequency of the bases adenine, cytosine, guanine, and thymine, and thus have a different density from bulk DNA such that they form a second or "satellite" band(s) when genomic DNA is separated along a cesium chloride density gradient using buoyant density centrifugation#DNA separation, buoyant density centrifugation. Sequences with a greater ratio of A+T display a lower density while those with a greater ratio of G+C display a higher density than the bulk of genomic DNA. Some repetitive sequences are ~50% G+C/A+T and thus have buoyant densities the same as bulk genomic DNA. These satellites are called "cryptic" satellites because they form a band ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Separation Processes
A separation process is a method that converts a mixture or a solution of chemical substances into two or more distinct product mixtures, a scientific process of separating two or more substances in order to obtain purity. At least one product mixture from the separation is enriched in one or more of the source mixture's constituents. In some cases, a separation may fully divide the mixture into pure constituents. Separations exploit differences in chemical properties or physical properties (such as size, shape, charge, mass, density, or chemical affinity) between the constituents of a mixture. Processes are often classified according to the particular properties they exploit to achieve separation. If no single difference can be used to accomplish the desired separation, multiple operations can often be combined to achieve the desired end. Different processes are also sometimes categorized by their separating agent, i.e. ''mass separating agents'' or ''energy separating agents ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
