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Section: Biological characteristics > Morphology. Cells of the genus Azotobacter are relatively large for bacteria (2–4 μm in diameter). They are usually oval but may take various forms from rods to spheres. In microscopic preparations, the cells can be dispersed or form irregular clusters or, occasionally, chains of v... | Wikipedia - Azotobacter - Biological characteristics > Morphology | 219 | 1,041 | null |
Section: Biological characteristics > Morphology > Cysts. Cysts of the genus Azotobacter are more resistant to adverse environmental factors than the vegetative cells; in particular, they are twice as resistant to ultraviolet light. They are also resistant to drying, ultrasound, and gamma and solar irradiation, but not... | Wikipedia - Azotobacter - Biological characteristics > Morphology > Cysts | 344 | 1,493 | null |
Section: Biological characteristics > Morphology > Germination of cysts. A cyst of the genus Azotobacter is the resting form of a vegetative cell; however, whereas usual vegetative cells are reproductive, the cyst of Azotobacter does not serve this purpose and is necessary for surviving adverse environmental factors. W... | Wikipedia - Azotobacter - Biological characteristics > Morphology > Germination of cysts | 333 | 1,589 | null |
Section: Biological characteristics > Physiological properties. Azotobacter respires aerobically, receives energy from redox reactions, using organic compounds as electron donors, and can use a variety of carbohydrates, alcohols, and salts of organic acids as sources of carbon. Azotobacter can fix at least 10 μg of nit... | Wikipedia - Azotobacter - Biological characteristics > Physiological properties | 341 | 1,488 | null |
Section: Biological characteristics > Genome. The nucleotide sequence of chromosomes of Azotobacter vinelandii, strain AvOP, is partially determined. This chromosome is a circular DNA molecule which contains 5,342,073 nucleotide pairs and 5,043 genes, of which 4,988 encode proteins. The fraction of guanine + cytosine p... | Wikipedia - Azotobacter - Biological characteristics > Genome | 159 | 692 | null |
Section: Nitrogen fixation. Azotobacter species are free-living, nitrogen-fixing bacteria; in contrast to Rhizobium species, they normally fix molecular nitrogen from the atmosphere without symbiotic relations with plants, although some Azotobacter species are associated with plants. Nitrogen fixation is inhibited in t... | Wikipedia - Azotobacter - Nitrogen fixation | 248 | 1,233 | null |
Section: Nitrogen fixation > Nitrogenase. Nitrogenase is the most important enzyme involved in nitrogen fixation. Azotobacter species have several types of nitrogenase. The basic one is molybdenum-iron nitrogenase. An alternative type contains vanadium; it is independent of molybdenum ions and is more active than the M... | Wikipedia - Azotobacter - Nitrogen fixation > Nitrogenase | 208 | 952 | null |
Section: Taxonomy. The genus Azotobacter was discovered in 1901 by Dutch microbiologist and botanist Martinus Beijerinck, who was one of the founders of environmental microbiology. He selected and described the species Azotobacter chroococcum – the first aerobic, free-living nitrogen fixer. In 1909, Lipman described Az... | Wikipedia - Azotobacter - Taxonomy | 310 | 1,229 | null |
Section: Characteristics. A. chroococcum is a microaerophilic plant growth-promoting rhizobacterium (PGRP), which is bacillus in shape and is Gram negative. As a mesophile, this bacterium grows best in moderate-temperature soils and requires a neutral pH environment. It is able to fix nitrogen under aerobic conditions.... | Wikipedia - Azotobacter chroococcum - Characteristics | 240 | 978 | null |
Section: Uses. Research has been carried out into A. chroococcum's potential applications in improving crop production. At least one study has so far shown a significant increase in crop production linked to the production of "auxins, cytokinins, and GA–like substances" by A. chroococcum. In addition to these biomolecu... | Wikipedia - Azotobacter chroococcum - Uses | 333 | 1,419 | null |
This bacterium can also be used to determine the nutrient composition of the soil. Since plants and A.chroccoccum both need phosphorus and potassium to grow, this bacterium can be used to determine if the soil is fit for crop growth, as it would thrive in soils that have these nutrients. A. chroococcum is also a possib... | Wikipedia - Azotobacter chroococcum - Uses | 170 | 809 | null |
Article: Contagium vivum fluidum. Contagium vivum fluidum (Latin: "contagious living fluid") was a phrase first used to describe a virus, and underlined its ability to slip through the finest ceramic filters then available, giving it almost liquid properties. Martinus Beijerinck (1851–1931), a Dutch microbiologist and ... | Wikipedia - Contagium vivum fluidum - Summary | 324 | 1,529 | null |
He found that although he could not culture the infectious agent, it would diffuse through an agar gel. This diffusion inspired him to put forward the idea of a non-cellular "contagious living fluid", which he called a "virus". This was somewhere between a molecule and a cell. Ivanovsky, irked that Beijerinck had not c... | Wikipedia - Contagium vivum fluidum - Summary | 340 | 1,600 | null |
Article: Electrocardiography. Electrocardiography is the process of producing an electrocardiogram (ECG or EKG), a recording of the heart's electrical activity through repeated cardiac cycles. It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the heart using electro... | Wikipedia - Electrocardiography - Summary | 337 | 1,592 | null |
In this way, the overall magnitude and direction of the heart's electrical depolarization is captured at each moment throughout the cardiac cycle. There are three main components to an ECG: The P wave, which represents depolarization of the atria. The QRS complex, which represents depolarization of the ventricles. The ... | Wikipedia - Electrocardiography - Summary | 266 | 1,231 | null |
Section: Medical uses. The overall goal of performing an ECG is to obtain information about the electrical functioning of the heart. Medical uses for this information are varied and often need to be combined with knowledge of the structure of the heart and physical examination signs to be interpreted. Some indications ... | Wikipedia - Electrocardiography - Medical uses | 347 | 1,588 | null |
Section: Electrocardiograph machines. Mechanical cardiographs (apex cardiogram), developed in the 19th century, recorded heart movements by transmitting heart or chest wall motions to a spring and air chamber system. A writing lever traced these movements onto a smoked rotating cylinder, producing a cardiogram. Their a... | Wikipedia - Electrocardiography - Electrocardiograph machines | 322 | 1,653 | null |
The machines are powered by mains power but they are designed with several safety features including an earthed (ground) lead. Other features include: Defibrillation protection: any ECG used in healthcare may be attached to a person who requires defibrillation and the ECG needs to protect itself from this source of ene... | Wikipedia - Electrocardiography - Electrocardiograph machines | 260 | 1,340 | null |
Section: Electrocardiograph machines > Cardiac monitors. Besides the standard electrocardiograph machine, there are other devices that can record ECG signals. Portable devices have existed since the Holter monitor was introduced in 1962. Traditionally, these monitors have used electrodes with patches on the skin to rec... | Wikipedia - Electrocardiography - Electrocardiograph machines > Cardiac monitors | 277 | 1,316 | null |
Section: Electrodes and leads > 12-Lead ECG. Leads are broken down into three types: limb; augmented limb; and precordial or chest. The 12-lead ECG has a total of three limb leads and three augmented limb leads arranged like spokes of a wheel in the coronal plane (vertical), and six precordial leads or chest leads that... | Wikipedia - Electrocardiography - Electrodes and leads > 12-Lead ECG | 276 | 1,305 | null |
Section: Electrodes and leads > Virtual Electrode. The virtual electrode is used to obtain useful measurements from the precordial leads, and also allows the creation of the augmented limb leads. The virtual electrode is known as Wilson's Central Terminal (WCT). For the precordial leads, WCT is formed by averaging the ... | Wikipedia - Electrocardiography - Electrodes and leads > Virtual Electrode | 226 | 907 | null |
Goldberger's modification is now used to produce each augmented limb lead, aVF, aVR, and aVL, which produces 50% larger amplitude leads than the standard WCT. Goldberger's WCT is formed according to the following: a V R = R A − L A + L L 2 {\displaystyle aVR=RA-{\frac {LA+LL}{2}}} a V L = L A − R A + L L 2 {\displaysty... | Wikipedia - Electrocardiography - Electrodes and leads > Virtual Electrode | 329 | 1,109 | null |
Section: Electrodes and leads > Limb leads. Leads I, II and III are called the limb leads. The electrodes that form these signals are located on the limbs – one on each arm and one on the left leg. The limb leads form the points of what is known as Einthoven's triangle. Lead I is the voltage between the (positive) left... | Wikipedia - Electrocardiography - Electrodes and leads > Limb leads | 192 | 700 | null |
Section: Electrodes and leads > Augmented limb leads. Leads aVR, aVL, and aVF are the augmented limb leads. They are derived from the same three electrodes as leads I, II, and III, but they use Goldberger's central terminal as their negative pole. Goldberger's central terminal is a combination of inputs from two limb e... | Wikipedia - Electrocardiography - Electrodes and leads > Augmented limb leads | 329 | 1,100 | null |
The negative pole is a combination of the right arm electrode and the left leg electrode: a V L = L A − 1 2 ( R A + L L ) = 3 2 ( L A − V W ) {\displaystyle aVL=LA-{\frac {1}{2}}(RA+LL)={\frac {3}{2}}(LA-V_{W})} Lead augmented vector foot (aVF) has the positive electrode on the left leg. The negative pole is a combinat... | Wikipedia - Electrocardiography - Electrodes and leads > Augmented limb leads | 327 | 1,038 | null |
Section: Electrodes and leads > Specialized leads. Additional electrodes may rarely be placed to generate other leads for specific diagnostic purposes. Right-sided precordial leads may be used to better study pathology of the right ventricle or for dextrocardia (and are denoted with an R (e.g., V5R). Posterior leads (V... | Wikipedia - Electrocardiography - Electrodes and leads > Specialized leads | 339 | 1,368 | null |
Section: Electrodes and leads > Lead locations on an ECG report. A standard 12-lead ECG report (an electrocardiograph) shows a 2.5 second tracing of each of the twelve leads. The tracings are most commonly arranged in a grid of four columns and three rows. The first column is the limb leads (I, II, and III), the second... | Wikipedia - Electrocardiography - Electrodes and leads > Lead locations on an ECG report | 238 | 990 | null |
Section: Electrophysiology. The study of the conduction system of the heart is called cardiac electrophysiology (EP). An EP study is performed via a right-sided cardiac catheterization: a wire with an electrode at its tip is inserted into the right heart chambers from a peripheral vein, and placed in various positions ... | Wikipedia - Electrocardiography - Electrophysiology | 166 | 711 | null |
Section: Interpretation. Interpretation of the ECG is fundamentally about understanding the electrical conduction system of the heart. Normal conduction starts and propagates in a predictable pattern, and deviation from this pattern can be a normal variation or be pathological. An ECG does not equate with mechanical pu... | Wikipedia - Electrocardiography - Interpretation | 214 | 1,086 | null |
Section: Interpretation > Theory. Interpretation of the ECG is ultimately that of pattern recognition. In order to understand the patterns found, it is helpful to understand the theory of what ECGs represent. The theory is rooted in electromagnetics and boils down to the four following points: depolarization of the hea... | Wikipedia - Electrocardiography - Interpretation > Theory | 335 | 1,632 | null |
Section: Interpretation > Background grid. ECGs are normally printed on a grid. The horizontal axis represents time and the vertical axis represents voltage. The standard values on this grid are shown in the adjacent image at 25mm/sec (or 40ms per mm): A small box is 1 mm × 1 mm and represents 0.1 mV × 0.04 seconds. A ... | Wikipedia - Electrocardiography - Interpretation > Background grid | 251 | 1,102 | null |
Section: Interpretation > Rate and rhythm. In a normal heart, the heart rate is the rate at which the sinoatrial node depolarizes since it is the source of depolarization of the heart. Heart rate, like other vital signs such as blood pressure and respiratory rate, change with age. In adults, a normal heart rate is betw... | Wikipedia - Electrocardiography - Interpretation > Rate and rhythm | 345 | 1,356 | null |
Once sinus rhythm is established, or not, the second question is the rate. For a sinus rhythm, this is either the rate of P waves or QRS complexes since they are 1-to-1. If the rate is too fast, then it is sinus tachycardia, and if it is too slow, then it is sinus bradycardia. If it is not a sinus rhythm, then determin... | Wikipedia - Electrocardiography - Interpretation > Rate and rhythm | 200 | 862 | null |
Section: Interpretation > Axis. The heart has several axes, but the most common by far is the axis of the QRS complex (references to "the axis" imply the QRS axis). Each axis can be computationally determined to result in a number representing degrees of deviation from zero, or it can be categorized into a few types. T... | Wikipedia - Electrocardiography - Interpretation > Axis | 342 | 1,484 | null |
Section: Interpretation > Time-Frequency Analysis in ECG Signal Processing. In electrocardiogram (ECG) signal processing, Time-Frequency Analysis (TFA) is an important technique used to reveal how the frequency characteristics of ECG signals change over time, especially in non-stationary signals such as arrhythmias or ... | Wikipedia - Electrocardiography - Interpretation > Time-Frequency Analysis in ECG Signal Processing | 338 | 1,549 | null |
Section: Interpretation > Limb leads and electrical conduction through the heart. The animation shown to the right illustrates how the path of electrical conduction gives rise to the ECG waves in the limb leads. What is green zone ? Recall that a positive current (as created by depolarization of cardiac cells) travelin... | Wikipedia - Electrocardiography - Interpretation > Limb leads and electrical conduction through the heart | 342 | 1,642 | null |
The SA node is too small for its depolarization to be detected on most ECGs. Frames 4–10 depict the depolarization traveling through the atria, towards the atrioventricular node. During frame 7, the depolarization is traveling through the largest amount of tissue in the atria, which creates the highest point in the P w... | Wikipedia - Electrocardiography - Interpretation > Limb leads and electrical conduction through the heart | 334 | 1,501 | null |
Depending on the mean electrical axis of the heart, this phenomenon can result in a Q wave in lead II as well. Following depolarization of the interventricular septum, the depolarization travels towards the apex of the heart. This is depicted by frames 15–17 and results in a positive deflection on all three limb leads,... | Wikipedia - Electrocardiography - Interpretation > Limb leads and electrical conduction through the heart | 342 | 1,461 | null |
Section: Interpretation > Ischemia and infarction. Ischemia or non-ST elevation myocardial infarctions (non-STEMIs) may manifest as ST depression or inversion of T waves. It may also affect the high frequency band of the QRS. ST elevation myocardial infarctions (STEMIs) have different characteristic ECG findings based ... | Wikipedia - Electrocardiography - Interpretation > Ischemia and infarction | 299 | 1,304 | null |
Section: Interpretation > Artifacts. An ECG tracing is affected by patient motion. Some rhythmic motions (such as shivering or tremors) can create the illusion of cardiac arrhythmia. Artifacts are distorted signals caused by a secondary internal or external sources, such as muscle movement or interference from an elect... | Wikipedia - Electrocardiography - Interpretation > Artifacts | 162 | 861 | null |
Section: Interpretation > A Method for Interpretation. Whitbread, consultant nurse and paramedic, suggests ten rules of the normal ECG, deviation from which is likely to indicate pathology. These have been added to, creating the 15 rules for 12-lead (and 15- or 18-lead) interpretation. Rule 1: All waves in aVR are nega... | Wikipedia - Electrocardiography - Interpretation > A Method for Interpretation | 343 | 1,252 | null |
Section: Diagnosis. Numerous diagnoses and findings can be made based upon electrocardiography, and many are discussed above. Overall, the diagnoses are made based on the patterns. For example, an "irregularly irregular" QRS complex without P waves is the hallmark of atrial fibrillation; however, other findings can be ... | Wikipedia - Electrocardiography - Diagnosis | 198 | 920 | null |
Rhythm disturbances or arrhythmias: Atrial fibrillation and atrial flutter without rapid ventricular response Premature atrial contraction (PACs) and premature ventricular contraction (PVCs) Sinus arrhythmia Sinus bradycardia and sinus tachycardia Sinus pause and sinoatrial arrest Sinus node dysfunction and bradycardia... | Wikipedia - Electrocardiography - Diagnosis | 350 | 1,359 | null |
left bundle branch block (ILBBB) Complete left bundle branch block (LBBB) Left anterior fascicular block (LAFB) Left posterior fascicular block (LPFB) Bifascicular block (LAFB plus LPFB) Trifascicular block (LAFP plus FPFB plus RBBB) QT syndromes Brugada syndrome Short QT syndrome Long QT syndromes, genetic and drug-in... | Wikipedia - Electrocardiography - Diagnosis | 270 | 1,041 | null |
Section: History. In 1872, Alexander Muirhead is reported to have attached wires to the wrist of a patient with fever to obtain an electronic record of their heartbeat. In 1882, John Burdon-Sanderson working with frogs, was the first to appreciate that the interval between variations in potential was not electrically q... | Wikipedia - Electrocardiography - History | 333 | 1,560 | null |
Einthoven also described the electrocardiographic features of a number of cardiovascular disorders. In 1897, the string galvanometer was invented by the French engineer Clément Ader. In 1901, Einthoven, working in Leiden, the Netherlands, used the string galvanometer: the first practical ECG. This device was much more ... | Wikipedia - Electrocardiography - History | 307 | 1,427 | null |
Section: Overview > Definition. Bacteriology is the study of bacteria and their relation to medicine. Bacteriology evolved from physicians needing to apply the germ theory to address the concerns relating to disease spreading in hospitals the 19th century. Identification and characterizing of bacteria being associated ... | Wikipedia - Bacteriology - Overview > Definition | 153 | 813 | null |
Section: Culturing bacteria. The growth of bacteria in laboratory cultures is the mainstay method used by bacteriologists. Both solid and liquid culture media are used. Solid culture medium is usually nutrient agar in a petri dish. The constituents of the nutrient agar vary according to the bacteria under investigation... | Wikipedia - Bacteriology - Culturing bacteria | 153 | 692 | null |
Section: History. Bacteria were first observed by the Dutch microscopist Antonie van Leeuwenhoek in 1676, using a single-lens microscope of his own design. Leeuwenhoek did not recognize bacteria as a distinct category of microorganisms, and referred to all microorganisms, including bacteria, protists, and microscopic a... | Wikipedia - Bacteriology - History | 324 | 1,550 | null |
The importance of bacteria was recognized as it led to a study of disease prevention and treatment of diseases by vaccines. Pasteur's research led to Ignaz Semmelweis and Joseph Lister researching the importance of sanitized hands in medical work. In the 1840s, Semmelweis' observations and ideas surrounding sanitary te... | Wikipedia - Bacteriology - History | 350 | 1,782 | null |
In Koch's postulates, he set out criteria to test if an organism is the cause of a disease, and these postulates are still used today. Both Koch and Pasteur played a role in improving antisepsis in medical treatment. In 1870–1885 the modern methods of bacteriology technique were introduced by the use of stains, and by ... | Wikipedia - Bacteriology - History | 313 | 1,474 | null |
The development of the transmission electron microscope allowed better visualization of cell structure and helped to clarify issues. In 1962, Stanier and van Niel published an influential definition of bacteria, proposing that bacteria be defined as prokaryotic cellular entities; they also specified three differences b... | Wikipedia - Bacteriology - History | 151 | 795 | null |
Article: Ethology. Ethology is a branch of zoology that studies the behaviour of non-human animals. It has its scientific roots in the work of Charles Darwin and of American and German ornithologists of the late 19th and early 20th century, including Charles O. Whitman, Oskar Heinroth, and Wallace Craig. The modern dis... | Wikipedia - Ethology - Summary | 150 | 705 | null |
Section: History > The beginnings of ethology. Ethologists have been concerned particularly with the evolution of behaviour and its understanding in terms of natural selection. In one sense, the first modern ethologist was Charles Darwin, whose 1872 book The Expression of the Emotions in Man and Animals influenced many... | Wikipedia - Ethology - History > The beginnings of ethology | 209 | 1,058 | null |
Section: History > Growth of the field. Due to the work of Konrad Lorenz and Niko Tinbergen, ethology developed strongly in continental Europe during the years prior to World War II. After the war, Tinbergen moved to the University of Oxford, and ethology became stronger in the UK, with the additional influence of Will... | Wikipedia - Ethology - History > Growth of the field | 180 | 848 | null |
Section: History > Social ethology. In 1972, the English ethologist John H. Crook distinguished comparative ethology from social ethology, and argued that much of the ethology that had existed so far was really comparative ethology—examining animals as individuals—whereas, in the future, ethologists would need to conce... | Wikipedia - Ethology - History > Social ethology | 219 | 1,056 | null |
Section: Determinants of behaviour > Instinct > Fixed action patterns. An important development, associated with the name of Konrad Lorenz though probably due more to his teacher, Oskar Heinroth, was the identification of fixed action patterns. Lorenz popularized these as instinctive responses that would occur reliably... | Wikipedia - Ethology - Determinants of behaviour > Instinct > Fixed action patterns | 203 | 1,038 | null |
Section: Determinants of behaviour > Learning > Cultural learning > Imitation. Imitation is an advanced behavior whereby an animal observes and exactly replicates the behavior of another. The National Institutes of Health reported that capuchin monkeys preferred the company of researchers who imitated them to that of r... | Wikipedia - Ethology - Determinants of behaviour > Learning > Cultural learning > Imitation | 167 | 824 | null |
Section: Determinants of behaviour > Learning > Cultural learning > Stimulus and local enhancement. Animals can learn using observational learning but without the process of imitation. One way is stimulus enhancement in which individuals become interested in an object as the result of observing others interacting with ... | Wikipedia - Ethology - Determinants of behaviour > Learning > Cultural learning > Stimulus and local enhancement | 224 | 1,170 | null |
Section: Determinants of behaviour > Learning > Cultural learning > Social transmission. A well-documented example of social transmission of a behaviour occurred in a group of macaques on Hachijojima Island, Japan. The macaques lived in the inland forest until the 1960s, when a group of researchers started giving them ... | Wikipedia - Ethology - Determinants of behaviour > Learning > Cultural learning > Social transmission | 159 | 788 | null |
Section: Determinants of behaviour > Learning > Teaching. Teaching is a highly specialized aspect of learning in which the "teacher" (demonstrator) adjusts their behaviour to increase the probability of the "pupil" (observer) achieving the desired end-result of the behaviour. For example, orcas are known to intentional... | Wikipedia - Ethology - Determinants of behaviour > Learning > Teaching | 269 | 1,357 | null |
Section: Mating and the fight for supremacy. Individual reproduction is the most important phase in the proliferation of individuals or genes within a species: for this reason, there exist complex mating rituals, which can be very complex even if they are often regarded as fixed action patterns. The stickleback's compl... | Wikipedia - Ethology - Mating and the fight for supremacy | 238 | 1,206 | null |
Section: Social behaviour. Several animal species, including humans, tend to live in groups. Group size is a major aspect of their social environment. Social life is probably a complex and effective survival strategy. It may be regarded as a sort of symbiosis among individuals of the same species: a society is composed... | Wikipedia - Ethology - Social behaviour | 268 | 1,353 | null |
Section: Social behaviour > Benefits and costs of group living. One advantage of group living is decreased predation. If the number of predator attacks stays the same despite increasing prey group size, each prey has a reduced risk of predator attacks through the dilution effect. Further, according to the selfish herd ... | Wikipedia - Ethology - Social behaviour > Benefits and costs of group living | 266 | 1,482 | null |
Section: Tinbergen's four questions for ethologists. Tinbergen argued that ethology needed to include four kinds of explanation in any instance of behaviour: Function – How does the behaviour affect the animal's chances of survival and reproduction? Why does the animal respond that way instead of some other way? Causat... | Wikipedia - Ethology - Tinbergen's four questions for ethologists | 276 | 1,429 | null |
Article: Plant virus. Plant viruses are viruses that have the potential to affect plants. Like all other viruses, plant viruses are obligate intracellular parasites that do not have the molecular machinery to replicate without a host. Plant viruses can be pathogenic to vascular plants ("higher plants"). Many plant viru... | Wikipedia - Plant virus - Summary | 337 | 1,698 | null |
Section: History. The discovery of plant viruses causing disease is often accredited to A. Mayer (1886) working in the Netherlands demonstrated that the sap of mosaic obtained from tobacco leaves developed mosaic symptom when injected in healthy plants. However the infection of the sap was destroyed when it was boiled.... | Wikipedia - Plant virus - History | 340 | 1,713 | null |
Section: Structure. Viruses are so small that they can only be observed under an electron microscope. The structure of a virus is given by its coat of proteins, which surround the viral genome. Assembly of viral particles takes place spontaneously. Over 50% of known plant viruses are rod-shaped (flexuous or rigid). The... | Wikipedia - Plant virus - Structure | 270 | 1,295 | null |
Section: Transmission > By insects. Plant viruses need to be transmitted by a vector, most often insects such as leafhoppers. One class of viruses, the Rhabdoviridae, has been proposed to actually be insect viruses that have evolved to replicate in plants. The chosen insect vector of a plant virus will often be the det... | Wikipedia - Plant virus - Transmission > By insects | 324 | 1,529 | null |
Many plant viruses encode within their genome polypeptides with domains essential for transmission by insects. In non-persistent and semi-persistent viruses, these domains are in the coat protein and another protein known as the helper component. A bridging hypothesis has been proposed to explain how these proteins aid... | Wikipedia - Plant virus - Transmission > By insects | 182 | 880 | null |
Section: Transmission > On seed and pollen. Plant virus transmission from generation to generation occurs in about 20% of plant viruses. When viruses are transmitted by seeds, the seed is infected in the generative cells and the virus is maintained in the germ cells and sometimes, but less often, in the seed coat. When... | Wikipedia - Plant virus - Transmission > On seed and pollen | 273 | 1,379 | null |
Section: Translation of plant viral proteins. 75% of plant viruses have genomes that consist of single stranded RNA (ssRNA). 65% of plant viruses have +ssRNA, meaning that they are in the same sense orientation as messenger RNA but 10% have -ssRNA, meaning they must be converted to +ssRNA before they can be translated.... | Wikipedia - Plant virus - Translation of plant viral proteins | 243 | 1,095 | null |
Section: Translation of plant viral proteins > 5' Cap. For translation to occur, eukaryotic mRNAs require a 5' Cap structure. This means that viruses must also have one. This normally consists of 7MeGpppN where N is normally adenine or guanine. The viruses encode a protein, normally a replicase, with a methyltransferas... | Wikipedia - Plant virus - Translation of plant viral proteins > 5' Cap | 177 | 784 | null |
Section: Translation of plant viral proteins > Genome packaging. Besides involvement in the infection process, viral replicase is a directly necessary part of the packaging of RNA viruses' genetic material. This was expected due to replicase involvement already being confirmed in various other viruses. The genome of Be... | Wikipedia - Plant virus - Translation of plant viral proteins > Genome packaging | 258 | 1,025 | null |
Section: Applications of plant viruses. Plant viruses can be used to engineer viral vectors, tools commonly used by molecular biologists to deliver genetic material into plant cells; they are also sources of biomaterials and nanotechnology devices. Knowledge of plant viruses and their components has been instrumental f... | Wikipedia - Plant virus - Applications of plant viruses | 254 | 1,327 | null |
Article: Tobacco mosaic virus. Tobacco mosaic virus (TMV) is a positive-sense single-stranded RNA virus species in the genus Tobamovirus that infects a wide range of plants, especially tobacco and other members of the family Solanaceae. The infection causes characteristic patterns, such as "mosaic"-like mottling and di... | Wikipedia - Tobacco mosaic virus - Summary | 173 | 811 | null |
Section: History. In 1886, Adolf Mayer first described the tobacco mosaic disease that could be transferred between plants, similar to bacterial infections. In 1892, Dmitri Ivanovsky gave the first concrete evidence for the existence of a non-bacterial infectious agent, showing that infected sap remained infectious eve... | Wikipedia - Tobacco mosaic virus - History | 318 | 1,656 | null |
For his work, he was awarded 1/4 of the Nobel Prize in Chemistry in 1946, even though it was later shown some of his conclusions (in particular, that the crystals were pure protein, and assembled by autocatalysis) were incorrect. The first electron microscopical images of TMV were made in 1939 by Gustav Kausche, Edgar ... | Wikipedia - Tobacco mosaic virus - History | 264 | 1,190 | null |
Section: Structure. Tobacco mosaic virus has a rod-like appearance. Its capsid is made from 2130 molecules of coat protein and one molecule of genomic single strand RNA, 6400 bases long. The coat protein self-assembles into the rod-like helical structure (16.3 proteins per helix turn) around the RNA, which forms a hair... | Wikipedia - Tobacco mosaic virus - Structure | 316 | 1,435 | null |
Section: Genome. The TMV genome consists of a 6.3–6.5 kbp single-stranded (ss) RNA. The 3’-terminus has a tRNA-like structure, and the 5’-terminus has a methylated nucleotide cap. (m7G5’pppG). The genome encodes 4 open reading frames (ORFs), two of which produce a single protein due to ribosomal readthrough of a leaky ... | Wikipedia - Tobacco mosaic virus - Genome | 233 | 815 | null |
Section: Disease cycle > Infection and transmission. After its multiplication, it enters the neighboring cells through plasmodesmata. The infection does not spread through contact with insects, but instead spreads by direct contact to the neighboring cells. For its smooth entry, TMV produces a 30 kDa movement protein c... | Wikipedia - Tobacco mosaic virus - Disease cycle > Infection and transmission | 163 | 774 | null |
Section: Disease cycle > Replication. Following entry into its host via mechanical inoculation, TMV uncoats itself to release its viral [+]RNA strand. As uncoating occurs, the MetHel:Pol gene is translated to make the capping enzyme MetHel and the RNA Polymerase. Then the viral genome will further replicate to produce ... | Wikipedia - Tobacco mosaic virus - Disease cycle > Replication | 266 | 1,132 | null |
Section: Host and symptoms. Like other plant pathogenic viruses, TMV has a very wide host range and has different effects depending on the host being infected. Tobacco mosaic virus has been known to cause a production loss for flue cured tobacco of up to two percent in North Carolina. It is known to infect members of n... | Wikipedia - Tobacco mosaic virus - Host and symptoms | 307 | 1,463 | null |
Section: Treatment and management. One of the common control methods for TMV is sanitation, which includes removing infected plants and washing hands in between each planting. Crop rotation should also be employed to avoid infected soil/seed beds for at least two years. As for any plant disease, looking for resistant s... | Wikipedia - Tobacco mosaic virus - Treatment and management | 334 | 1,485 | null |
In the study, treated tobacco plants had more growth and less build-up of TMV virions than tobacco plants that hadn't been treated. A research has been conducted by H.Fraenkel-Conrat to show the influence of acetic acid on the Tobacco Mosaic Virus. According to the research, 67% acetic acid resulted as degradation of t... | Wikipedia - Tobacco mosaic virus - Treatment and management | 179 | 847 | null |
Section: Scientific and environmental impact. The large amount of literature about TMV and its choice for many pioneering investigations in structural biology (including X-ray diffraction and X-ray crystallography), virus assembly and disassembly, and so on, are fundamentally due to the large quantities that can be obt... | Wikipedia - Tobacco mosaic virus - Scientific and environmental impact | 175 | 831 | null |
Section: Applications. Plant viruses can be used to engineer viral vectors, tools commonly used by molecular biologists to deliver genetic material into plant cells; they are also sources of biomaterials and nanotechnology devices. Viral vectors based on TMV include those of the magnICON and TRBO plant expression techn... | Wikipedia - Tobacco mosaic virus - Applications | 294 | 1,357 | null |
Section: Activity and goals. EuropaBio is engaged in dialogue with the European Parliament, the European Commission, and the Council of Ministers to influence legislation on biotechnology. EuropaBio represents two sectors of the biotech industry. White or industrial biotechnology is the application of biotechnology for... | Wikipedia - EuropaBio - Activity and goals | 227 | 1,264 | null |
Article: European Federation of Biotechnology. The European Federation of Biotechnology (EFB) was established by European scientists in 1978. It is a non-profit federation of national biotechnology associations, learned societies, universities, scientific institutes, biotechnology companies and individual biotechnologi... | Wikipedia - European Federation of Biotechnology - Summary | 186 | 1,085 | null |
Section: Journals. EFB Bioeconomy Journal covers the science, natural and social sciences, the technologies and the humanities related to bioeconomy and its surrounding political, business, ethics, regulatory, social, and financial milieu. The peer-reviewed journal publishes original research papers, authoritative revi... | Wikipedia - European Federation of Biotechnology - Journals | 188 | 1,074 | null |
Article: A History of British Fishes. A History of British Fishes is a natural history book by William Yarrell, serialised in nineteen parts from 1835, and then published bound in two volumes in 1836. It is a handbook or field guide systematically describing every type of fish found in the British Isles, with an articl... | Wikipedia - A History of British Fishes - Summary | 321 | 1,604 | null |
Section: Author. William Yarrell (1784–1856) was the son of Francis Yarrell and his wife Sarah, née Blane. William's father and his cousin William Jones were partners as booksellers and newsagents in London. William joined the business in 1803 after leaving school, and inherited the company in 1850. Yarrell had the fre... | Wikipedia - A History of British Fishes - Author | 254 | 1,198 | null |
Section: Format. Yarrell was a great admirer of Thomas Bewick (he named a new wildfowl species "Bewick's swan" after the engraver). Bewick's A History of British Birds, published in two volumes in 1797 and in 1804, had brought him nationwide fame, and since Yarrell owned several editions of Bewick's books, he followed ... | Wikipedia - A History of British Fishes - Format | 309 | 1,516 | null |
A typical example is Yarrell's first entry, for the perch. As well as the expected detailed anatomical and geographical information, in the five-page text he notes: In rivers, the Perch prefers the sides of the stream rather than the rapid parts of the current, and feeds indiscriminately upon insects, worms, and small ... | Wikipedia - A History of British Fishes - Format | 210 | 914 | null |
Section: Production and publication. Yarrell's illustrations were wood engravings made using the techniques pioneered by Bewick in which boxwood blocks were engraved on their ends using a burin, a tool with a V‑shaped tip. The new illustrations for the fish book were drawn onto the blocks by Alexander Fussell and cut b... | Wikipedia - A History of British Fishes - Production and publication | 321 | 1,589 | null |
Section: Production and publication > Editions. Three editions and three supplements were published by Van Voorst. 1835–36 Two volumes originally published in 19 parts. 226 species described and figured, and 140 vignettes. Volume 1, 408 pp., volume 2, 472 pp. 1839 Supplement, 27 new species. Volume 1, 48 pp., volume 2,... | Wikipedia - A History of British Fishes - Production and publication > Editions | 189 | 811 | null |
Section: Reception. Publications writing contemporary positive reviews of A History of British Fishes included The Athenaeum, The Gentleman's Magazine, Leigh Hunt's London Journal, the London Medical Gazette and The Quarterly Review. The Gentleman's Magazine said ... the task could not have been undertaken by one more ... | Wikipedia - A History of British Fishes - Reception | 325 | 1,615 | null |
There was a generally appreciative reception from Yarrell's fellow naturalists. Prideaux John Selby, an ornithologist and natural history artist, wrote to Jardine after receiving the first part to say how impressed he was with the beautifully executed woodcuts and the quality of the printing, and later, when he had the... | Wikipedia - A History of British Fishes - Reception | 266 | 1,219 | null |
Section: Cited texts. Jackson, Christine E (2022). A Newsworthy Naturalist: The Life of William Yarrell. Oxford: John Beaufoy. ISBN 978-1913679-04-0. McGhie, Henry A (2017). Henry Dresser and Victorian Ornithology: Birds, Books and Business. Manchester: Manchester University Press. ISBN 978-1-78499-413-6. Peck, Robert ... | Wikipedia - A History of British Fishes - Cited texts | 219 | 750 | null |
Article: Portland Press Excellence in Science Award. The Portland Press Excellence in Science Award was an annual award instituted in 1964 to recognize notable research in any branch of biochemistry undertaken in the UK or Republic of Ireland. It was initially called the CIBA Medal and Prize, then the Novartis Medal an... | Wikipedia - Portland Press Excellence in Science Award - Summary | 176 | 873 | null |
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