Sliding microtubule hypothesis

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Sliding microtubule hypothesis

Reduced resistance to microtubule sliding may also be a key property displayed by other suppressor mutations that affect the outer-arm dynein HCs and the I1 dynein Table 12.1. This hypothesis would be consistent with the original model suggesting that the wild-type function of the DRC is to globally inhibit dynein activity. ; plural: flagella) is a lash-like appendage that protrudes from the cell body of certain bacterial and eukaryotic cells. The similar structure in the archaea functions in the same way but is structurally different and has been termed the archaellum (as of 2012). The primary role of the flagellum is locomotion, but it also often has function as a sensory organelle, being sensitive to chemicals and temperatures outside the cell. Flagella are organelles defined by function rather than structure. Large differences occur between different types of flagella; the prokaryotic and eukaryotic flagella differ greatly in protein composition, structure, and mechanism of propulsion. An example of a flagellated bacterium is the ulcer-causing Helicobacter pylori, which uses multiple flagella to propel itself through the mucus lining to reach the stomach epithelium. Prokaryotic flagella run in a rotary movement, while eukaryotic flagella run in a bending movement.

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Kinesin-1 heavy chain mediates

Sliding microtubule hypothesis

Microtubules are typically observed to buckle and loop during interphase in cultured cells by an unknown mechanism. We show that lateral microtubule movement and looping is a result of microtubules sliding against one another in interphase Drosophila S2 cells. Start studying group project management software AP Biology. a eukaryotic cell structure consisting of a "9 0" arrangement of microtubule triplets; the basal light and the glory body may organize the microtubule S2 hypothesis testing assembly of a cilium or flagellum. flagella) is a lash-like appendage that protrudes from sliding microtubule hypothesis the cell body of certain prokaryotic and eukaryotic cells Study online flashcards and notes for Biology including Library Pirate Interactive Figures Vivid images with related questions help you come to class. Print Campbell Biology 10th edition Chapter 12 flashcards and study them anytime, anywhere A flagellum (/ f l ə ˈ dʒ ɛ l əm /; sliding microtubule hypothesis plural: Send questions or comments to doi. Issuu is sliding microtubule hypothesis a digital publishing platform that makes it simple to publish magazines, catalogs, newspapers, books, and more online. It includes the specific physics underlying different phases. report write up Disruption of Motor Self-Dimerization Increases Microtubule graffiti: art or crime and Dynactin Affinity (A) Representative 2D class averages of negative stain EM images of wild. Learn vocabulary, terms, and more with flashcards, leaderships role in the business world games, and other study tools. Article by Revathi Ananthakrishnan and Allen Ehrlicher providing an in-depth analysis of cell movement. Your browser will take you to a Web page (URL) associated with that DOI name.

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Encyclopedia of Biological Chemistry - 2nd Edition

Sliding microtubule hypothesis

In this study, we investigated how microtubule motors organize microtubules in Drosophila neurons. We showed that, during the initial stages of axon outgrowth, microtubules display mixed polarity and minus-end-out microtubules push the tip of the axon, consistent with kinesin-1 driving outgrowth by sliding antiparallel. Although coupling between ATP hydrolysis and motility was not demonstrated. Here we report that sea urchin egg kinesin, prepared either with or without a 5′-adenylyl imido-diphosphate(AMPPNP)-induced microtubule binding step, also possesses significant microtubule-activated ATPase activity when Mg-ATP is used as a substrate. PY - 1988Y1 - 1988N2 - Coupling between ATP hydrolysis and microtubule movement was demonstrated several years ago in flagellar axonemes1,2 and subsequent studies suggest that the relevant microtubule motor, dynein, uses ATP to drive microtubule sliding by a cross-bridge mechanism analogous to that of myosin in muscles3,4. This ATPase activity is inhibited in a dose-dependent manner by addition of Mg-free ATP, by chelation of Mg Addition of these same reagents also inhibits the microtubule-translocating activities of sea urchin egg kinesin in a dose-dependent manner, supporting the hypothesis that kinesin-driven motility is coupled to the microtubule-activated Mg TY - JOURT1 - Correlation between the ATPase and microtubule translocating activities of sea urchin egg kinesin AU - Cohn, Stanley A. Kinesin5, a microtubule-based motility protein which may participate in organelle transport and mitosis6, binds microtubules in a nucleo-tide-sensitive manner5,7,8, and requires hydrolysable nucleotides to translocate microtubules over a glass surface 9,10. Recently, neuronal kinesin was shown to possess microtubule-activated ATPase activity11,12 although coupling between ATP hydrolysis and motility was not demonstrated. Here we report that sea urchin egg kinesin, prepared either with or without a 5′-adenylyl imido-diphosphate(AMPPNP)-induced microtubule binding step, also possesses significant microtubule-activated ATPase activity when Mg-ATP is used as a substrate. This ATPase activity is inhibited in a dose-dependent manner by addition of Mg-free ATP, by chelation of Mg2 with EDTA, by addition of Na3VO4, or by addition of AMPPNP with or without Mg2 Addition of these same reagents also inhibits the microtubule-translocating activities of sea urchin egg kinesin in a dose-dependent manner, supporting the hypothesis that kinesin-driven motility is coupled to the microtubule-activated Mg2 -ATPase activity. AB - Coupling between ATP hydrolysis and microtubule movement was demonstrated several years ago in flagellar axonemes1,2 and subsequent studies suggest that the relevant microtubule motor, dynein, uses ATP to drive microtubule sliding by a cross-bridge mechanism analogous to that of myosin in muscles3,4. Kinesin5, a microtubule-based motility protein which may participate in organelle transport and mitosis6, binds microtubules in a nucleo-tide-sensitive manner5,7,8, and requires hydrolysable nucleotides to translocate microtubules over a glass surface 9,10.

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Sliding microtubule hypothesis

Sliding microtubule hypothesis

Although evidence suggests that kinesins-14 act by driving the sliding of MT bundles in different areas of the spindle, such sliding activity had never been demonstrated directly. To test the hypothesis that kinesins-14 can induce MT sliding in living cells, we developed an in vivo assay, which involves overexpression of the. Linkages appear to be a unique feature of motile cilia and flagella, whether or not radial spokes and central-pair microtubules are present. They are obviously present in the motile 9 0 flagella of eel sperm . However, high-resolution electron microscopy studies on non-motile, primary cilia are limited, and it is difficult to clearly identify interdoublet linkages, even when images are reinforced by nine-fold rotation . These authors suggest that the term “9v” (variable) is a more accurate description of axoneme architecture for primary cilia in a wide variety of tissues and organisms. In addition, most of the polypeptides that have been proposed as potential subunits of the –DRC links as was previously believed. The identification of other components that help to maintain outer-doublet integrity should be a high priority. An interesting possibility is that a specific subset of inner-arm dyneins may be involved link could suppress paralysis by reducing resistance to sliding. Reduced resistance to microtubule sliding may also be a key property displayed by other suppressor mutations that affect the outer-arm dynein HCs and the I1 dynein ().

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Pioneer Peter Satir investigating the structural basis for.

Sliding microtubule hypothesis

Peter Satir – investigating the structural basis. for a sliding microtubule model of ciliary. hypothesis that microtubules slide during In this study, we investigated how microtubule motors organize microtubules in Drosophila neurons. We showed that, during the initial stages of axon outgrowth, microtubules display mixed polarity and minus-end-out microtubules push the tip of the axon, consistent with kinesin-1 driving outgrowth by sliding antiparallel microtubules. At later stages, the microtubule orientation in the axon switches from mixed to uniform polarity with plus-end-out. Dynein knockdown prevents this rearrangement and results in microtubules of mixed orientation in axons and accumulation of microtubule minus-ends at axon tips. Microtubule reorganization requires recruitment of dynein to the actin cortex, as actin depolymerization phenocopies dynein depletion, and direct recruitment of dynein to the membrane bypasses the actin requirement. Our results show that cortical dynein slides ‘minus-end-out’ microtubules from the axon, generating uniform microtubule arrays. We speculate that differences in microtubule orientation between axons and dendrites could be dictated by differential activity of cortical dynein. Motor proteins can move along filaments called microtubules to transport proteins and other materials to different parts of the cell.

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OMIM Entry - * 157140 - MICROTUBULE-ASSOCIATED PROTEIN TAU; MAPT

Sliding microtubule hypothesis

Microtubule-associated protein tau; mapt - mtbt1 - mapt This is a list of citations and summaries of veterinary research journal articles which are applicable to mitral valve disease and cavalier King Charles spaniels. The pattern of inheritance of these defects was not consistent with any simple genetic hypothesis. In the days after moderate constriction plasma volume and body weight increased (with development of ascites and edema); blood pressure, sodium excretion, plasma renin acvitity, and plasma aldosterone returned to normal. Accurate measurement of volume was achieved by the use of a water-filled, thin latex balloon in the right ventricle connected to a special volume loading and transducing chamber. This list is in chronological order, from 1965 to the current date, with the most recent additions added at the bottom of this page. Patent ductus arteriosus in dogs of poodle ancestry and fibrous subaortic stenosis in Newfoundlands were shown provisionally to be transmitted in a manner consistent with autosomal dominant inheritance. In animals in which blood pressure was not restored, plasma renin activity and plasma aldosterone remained elevated throughout the period of constriction. Pressure was measured with a miniature pressure transducer mounted within the balloon. Hyper-linked titles are linked to the actual articles which are available on-line. The significance of these findings is considered in relation to present and future understanding of the etiology and pathogenesis of congenital heart disease." . Single injections of converting enzyme inhibitor reduced blood pressure when plasma renin activity was elevated. Wide variations in loading conditions were achieved by changing the volume of air above the volumetric chamber. Preliminary genetic studies confirmed the specific hereditary transmission of valvular pulmonic stenosis in beagles, persistent right aortic arch in German shepherds, and conal septal defects (including ventricular septal defects and tetralogy of Fallot) in keeshonden. The initial response to constriction was a reduction in blood pressure, a rise in plasma renin activity, plasma aldosterone, and water intake, and nearly complete sodium retention. Quote: The instantaneous isovolumic and ejecting pressure-volume relationship of the right ventricle was studied in 11 cross-circulated, isolated canine hearts to characterize the right ventricular contractile state. The principles in selecting the chamber or vessel for the injection are based primarily upon the knowledge that cardiac valves are normally unidirectional and blood pressures in the left atrium, left ventricle, and aorta normally exceed the pressures in corresponding right heart structures. In dogs with suspected valvular insufficiencies, injections are made into the vessel or cardiac chamber from which the contrast medium would regurgitate (i.e., immediately “down stream” from the affected valve). (2) These genetic factors have specific effects on cardiac morphogenesis, resulting in specific types of cardiovascular malformations. L Watkins, Jr, J A Burton, E Haber, J R Cant, F W Smith, A C Barger. Constriction of the pulmonary artery or thoracic inferior vena cava was maintained for 2 wk while daily measurements were made of plasma renin activity, plasma aldosterone, plasma volume, hematocrit, serum sodium and potassium concentrations, sodium and water balance, body weight, and arterial, caval, and atrial pressures. In selective angiocardiography, the contrast medium is injected through a catheter, the tip of which has been positioned into a specific vessel or cardiac chamber to visualize best a suspected abnormality based upon the clinical findings. On the basis of these observations, two hypotheses were made: (1) Genetic factors are determinants of certain types of congenital heart disease in the dog. Quote: "It was considered that the relationship between dp/dt and simultaneously developed pressure during the course of isovolumic contraction might afford a more accurate measure of contractility than the maximum rate of intraventricular pressure rise (peak dp/dt). In conclusion, the determination of dp/dt and intraventricular pressure throughout isovolumic contraction in the presence of variable arterial pressure and small changes of preload provides a useful, simple, and experimentally verified approach to the assessment of alterations of the contractile state of the heart in intact man." . Quote: "The role of the renin-angiotensin-aldosterone system in the development of congestive failure has been assessed in the conscious dog by use of the nonapeptide converting enzyme inhibitor. Quote: Angiocardiograms are radiographs made while a radiopaque medium is circulating through the heart (and closely associated vessels). Breed-specific prevalence rates were significantly greater in purebred dogs than in mongrels, and the breed distributions of patent ductus arteriosus, pulmonic stenosis, subaortic stenosis, persistent right aortic arch, and tetralogy of Fallot were significantly different than would be expected if all breeds were equally susceptible to each type of malformation. Patent ductus arteriosus, as in man, was found predominantly in females.

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Cell | Definition, Types, & Functions - Actin filaments | Britannica.com

Sliding microtubule hypothesis

Some of these beads attach to the outer doublet microtubules that comprise the flagellar axoneme. In this case, two beads were attached to doublet microtubules on opposite sides of the flagellum. As the flagellum bends, the sliding between these doublet microtubules is demonstrated by the movement of the two beads. This is a list of citations and summaries of veterinary research journal articles which are applicable to mitral valve disease and cavalier King Charles spaniels. The pattern of inheritance of these defects was not consistent with any simple genetic hypothesis. This list is in chronological order, from 1965 to the current date, with the most recent additions added at the bottom of this page. Patent ductus arteriosus in dogs of poodle ancestry and fibrous subaortic stenosis in Newfoundlands were shown provisionally to be transmitted in a manner consistent with autosomal dominant inheritance. Hyper-linked titles are linked to the actual articles which are available on-line. Preliminary genetic studies confirmed the specific hereditary transmission of valvular pulmonic stenosis in beagles, persistent right aortic arch in German shepherds, and conal septal defects (including ventricular septal defects and tetralogy of Fallot) in keeshonden. The principles in selecting the chamber or vessel for the injection are based primarily upon the knowledge that cardiac valves are normally unidirectional and blood pressures in the left atrium, left ventricle, and aorta normally exceed the pressures in corresponding right heart structures. In dogs with suspected valvular insufficiencies, injections are made into the vessel or cardiac chamber from which the contrast medium would regurgitate (i.e., immediately “down stream” from the affected valve). (2) These genetic factors have specific effects on cardiac morphogenesis, resulting in specific types of cardiovascular malformations.

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Conceptual Glossary of Medical Terms.

Sliding microtubule hypothesis

Jul 6, 2014. Microtubule doublets dissociated from isolated axonemes can be reconstituted and will slide past one another when ATP is provided. Microtubules are filamentous intracellular structures that are responsible for various kinds of movements in all eukaryotic cells. Microtubules are involved in nucleic and cell division, organization of intracellular structure, and intracellular transport, as well as ciliary and flagellar motility. Because the functions of microtubules are so critical to the existence of eukaryotic cells (including our own), it is important that we understand their composition, how they are assembled and disassembled, and how their assembly/disassembly and functions are regulated by cells. For the sake of brevity, only the very basic and universal concepts about microtubules and their organization into flagella will be presented here, leaving many questions unanswered. You will find that textbooks provide more complete descriptions of microtubules and their structures and functions, but they also leave many questions unanswered. Textbooks seldom tell us is how much science knows and does not know about them, and of course they cannot be up to date with the latest discoveries. To fully understand a subject it is important to go to multiple sources. If the subject is especially important to you, you should seek the primary literature, namely original research reports.

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Geometric clutch" hypothesis of axonemal. - Oakland University

Sliding microtubule hypothesis

Or the axoneme would break apart. The computer simu- lation was able to calculate an upper limit estimate of elasticity 0.6 dyne/cm by using a value just large enough to “arrest” the microtubule sliding and produc- ing the characteristic configuration observed in cilia. The nexin link periodicity of = 100 nm Stephens, 19701. Port Manteaux churns out silly new words when you feed it an idea or two. Enter a word (or two) above and you'll get back a bunch of portmanteaux created by jamming together words that are conceptually related to your inputs. For example, enter "giraffe" and you'll get back words like "gazellephant" and "gorilldebeest". Enter "south america" and "chess" and you'll get back words like "checkuador". It uses the Datamuse API to find related words, and then finds combinations of these words that pair well together phonetically. Note: The algorithm tries reconstruct a spelling for the new word after generating its pronunciation, and sometimes this spelling isn't quite right.

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Differential roles of microtubule assembly and sliding in proplatelet.

Sliding microtubule hypothesis

To further test this hypothesis, we sought methods to tease apart the relative contributions of microtubule sliding and microtubule assembly in elaborating the proplatelet microtubule array. To do so, we studied the outgrowth of proplatelets under conditions that arrest microtubule assembly while maintaining substantial. Regulation of ciliary and flagellar motility requires spatial control of dynein-driven microtubule sliding. However, the mechanism for regulating the location and symmetry of dynein activity is not understood. One hypothesis is that the asymmetrically organized central apparatus, through interactions with the radial spokes, transmits a signal to regulate dynein-driven microtubule sliding between subsets of doublet microtubules. Based on this model, we hypothesized that the orientation of the central apparatus defines positions of active microtubule sliding required to control bending in the axoneme. To test this, we induced microtubule sliding in axonemes isolated from wild-type and mutant Chlamydomonas cells, and then used electron microscopy to determine the orientation of the central apparatus. Transverse sections of wild-type axonemes revealed that the C1 microtubule is predominantly oriented toward the position of active microtubule sliding. In contrast, the central apparatus is randomly oriented in axonemes isolated from radial spoke deficient mutants. For outer arm dynein mutants, the C1 microtubule is oriented toward the position of active microtubule sliding in low calcium buffer, but is randomly oriented in high calcium buffer.

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Inhibition of Microtubule Sliding by Ni2+ and Cd2 Evidence for a.

Sliding microtubule hypothesis

Mar 30, 1993. hours, and thawed, disintegrated by microtubule sliding when 1 mM MgATP was. ma1 microtubules. These results indicate a predisposition for sliding between elements 7 and 8 over that between doublets 2 and 3, perhaps due to a disparity. a hypothesis which will be examined in a future study. ; plural: flagella) is a lash-like appendage that protrudes from the cell body of certain prokaryotic and eukaryotic cells. The primary role of the flagellum is locomotion, but it also often has function as a sensory organelle, being sensitive to chemicals and temperatures outside the cell. Flagella are organelles defined by function rather than structure. Large differences occur between different types of flagella; the prokaryotic and eukaryotic flagella differ greatly in protein composition, structure, and mechanism of propulsion. An example of a flagellated bacterium is the ulcer-causing Helicobacter pylori, which uses multiple flagella to propel itself through the mucus lining to reach the stomach epithelium. Prokaryotic flagella run in a rotary movement, while eukaryotic flagella run in a bending movement. The prokaryotic flagella use a rotary motor, and the eukaryotic flagella use a complex sliding filament system.

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