TAU is a microtubule-associated protein that promotes microtubule assembly and stability in the axon.TAU is missorted and aggregated in an array of diseases known as tauopathies.Microtubules are essential for neuronal...TAU is a microtubule-associated protein that promotes microtubule assembly and stability in the axon.TAU is missorted and aggregated in an array of diseases known as tauopathies.Microtubules are essential for neuronal function and regulated via a complex set of post-translational modifications,changes of which affect microtubule stability and dynamics,microtubule interaction with other proteins and cellular structures,and mediate recruitment of microtubule-severing enzymes.As impairment of microtubule dynamics causes neuronal dysfunction,we hypothesize cognitive impairment in human disease to be impacted by impairment of microtubule dynamics.We therefore aimed to study the effects of a disease-causing mutation of TAU(P301L)on the levels and localization of microtubule post-translational modifications indicative of microtubule stability and dynamics,to assess whether P301L-TAU causes stability-changing modifications to microtubules.To investigate TAU localization,phosphorylation,and effects on tubulin post-translational modifications,we expressed wild-type or P301L-TAU in human MAPT-KO induced pluripotent stem cell-derived neurons(i Neurons)and studied TAU in neurons in the hippocampus of mice transgenic for human P301L-TAU(p R5 mice).Human neurons expressing the longest TAU isoform(2N4R)with the P301L mutation showed increased TAU phosphorylation at the AT8,but not the p-Ser-262 epitope,and increased polyglutamylation and acetylation of microtubules compared with endogenous TAU-expressing neurons.P301L-TAU showed pronounced somatodendritic presence,but also successful axonal enrichment and a similar axodendritic distribution comparable to exogenously expressed 2N4R-wildtype-TAU.P301L-TAU-expressing hippocampal neurons in transgenic mice showed prominent missorting and tauopathy-typical AT8-phosphorylation of TAU and increased polyglutamylation,but reduced acetylation,of microtubules compared with non-transgenic littermates.In sum,P301L-TAU results in changes in microtubule PTMs,suggestive of impairment of microtubule stability.This is accompanied by missorting and aggregation of TAU in mice but not in i Neurons.Microtubule PTMs/impairment may be of key importance in tauopathies.展开更多
Fe（OH）3 precursor sol was prepared by a sol-gel method. The precursor sol was dipped onto the absorbent cotton, and gel was formed on the absorbent cotton template after the volatilization of moisture. Fe2O3 microtu...Fe（OH）3 precursor sol was prepared by a sol-gel method. The precursor sol was dipped onto the absorbent cotton, and gel was formed on the absorbent cotton template after the volatilization of moisture. Fe2O3 microtubules were synthesized after the process of self-propagation or calcination. The phase, morphology, and particle diameter of the samples were examined by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, and the magnetic properties of the samples were measured using a vibrating sample magnetometer （VSM）. The external diameters of Fe2O3 microtubules ranged between 8 and 13 μm, and the wall thicknesses ranged between 0.5 and 2 μm. The type of the calcination method plays a significant role in developing the Fe2O3 phase and the variation in the magnetic properties in the sol-gel template complexing method. γ-Fe2O3 was synthesized by a self-propagation method. However, α-Fe203 was synthesized after calcination at 400℃ for 2 h. The coercivity of the samples synthesized by calcination at 400℃ for 2 h after self-propagation was found to increase significantly, thereby presenting hard magnetic properties.展开更多
Ran is an evolutionarily conserved eukaryotic GTPase that directly participates in cell cycle and whose loss affects many biological processes.We have identified cDNA of TaRAN/,a novel Ran GTPase homologous gene in wh...Ran is an evolutionarily conserved eukaryotic GTPase that directly participates in cell cycle and whose loss affects many biological processes.We have identified cDNA of TaRAN/,a novel Ran GTPase homologous gene in wheat(Triticum aestivum L.cv.Jingdong No.1).The cytoplasmic microtu-bules play an important role in cytoplasmic organization,cell division,and the correct transmission of genetic information in fission yeast cell.Using the fission yeast system in vivo experiments,overexpression of TaRAN/produced defective spindle microtubules,probably resulting in chromosome missegregation we reported previously.The microtubules of antisense TaRANI yeast cells were physically disrupted.This suggested that TaRAN/plays a role in mitotic spindle assembly and microtubule integrity and stability.Ultrastructural analysis under transmission electron microscope(TEM)showed abnormal nuclear membranes in the overexpression TaRAN/yeast cells,abnormal vacuole structures and disorganized membranes in the antisense TaRANI yeast cells.These results suggested that TaRANI was essential for all nucleocytoplasmic transport events.展开更多
This is a review paper describing recent findings about the physical properties of centriolar microtubules. Microtubules are the principal structures making up the centrioles. The centrioles in turn are the principal ...This is a review paper describing recent findings about the physical properties of centriolar microtubules. Microtubules are the principal structures making up the centrioles. The centrioles in turn are the principal agents in cell duplication and division (mitosis). The microtubules are seen to be long hollow cylinders: approximately 400 nm in length, with a 24 nm outside diameter, and a 5 nm wall thickness. Within the centrioles, the microtubules are arranged into nine parallel sets of triplets—thus numbering 27 parallel cylinders per centriole. Each normal eukaryotic (human and animal) cell, not in mitosis, has two perpendicular centrioles connected at their proximal (base) ends. During mitosis, these two become four, resulting in a total of 108 centriolar microtubules. The structure of the microtubules themselves is found to consist of 13 parallel filaments making up the cylinder walls. The filaments are composed of approximately 40 and β-tubulin connected end-to-end with their proximal (base) ends anchored in γ-tubulin. The longitudinal vibrations of the filaments are believed to create an electro-magnetic field within the cell which plays an important role in mitosis.展开更多
There are six micronuclear divisions during conjugation of Paramecium caudatum:three prezygotic and three postzygotic divisions.Four haploid nuclei are formed during the first two meiotic prezygotic divisions.Usually ...There are six micronuclear divisions during conjugation of Paramecium caudatum:three prezygotic and three postzygotic divisions.Four haploid nuclei are formed during the first two meiotic prezygotic divisions.Usually only one meiotic product is located in the paroral cone(PC)region at the completion of meiosis,which survives and divides mitotically to complete the third prezygotic division to yield a stationary and a migratory pronucleus.The remaining three located outside of the PC degenerate.The migratory pronuclei are then exchanged between two conjugants and fuse with the stationary pronuclei to form synkarya,which undergo three successive divisions(postzygotic divisions).However,little is known about the surviving mechanism of the PC nuclei.In the current study,stage-specific appearance of cytoplasmic microtubules(cMTs)was indicated during the third prezygotic division by immunofluorescence labeling with anti-alpha tubulin antibodies surrounding the surviving nuclei,including the PC nuclei and the two types of prospective pronuclei.This suggested that cMTs were involved in the formation of a physical barrier,whose function may relate to sequestering and protecting the surviving nuclei from the major cytoplasm,where degeneration of extra-meiotic products occurs,another important nuclear event during the third prezygotic division.展开更多
There are six micronuclear divisions during conjugation of Paramecium caudatum： three prezygotic and three postzygotic divisions. Four haploid nuclei are formed during the first two meiotic prezygotic divisions. Usua...There are six micronuclear divisions during conjugation of Paramecium caudatum： three prezygotic and three postzygotic divisions. Four haploid nuclei are formed during the first two meiotic prezygotic divisions. Usually only one meiotic product is located in the paroral cone （PC） region at the completion of meiosis, which survives and divides mitotically to complete the third prezygotic division to yield a stationary and a migratory pronucleus. The remaining three located outside of the PC degenerate. The migratory pronuclei are then exchanged between two conjugants and fuse with the stationary pronuclei to form synkarya, which undergo three successive divisions （postzygotic divisions）. However, little is known about the surviving mechanism of the PC nuclei. In the current study, stage-specific appearance of cytoplasmic microtubules （cMTs） was indicated during the third prezygotic division by immunofluorescence labeling with anti-alpha tubulin antibodies surrounding the surviving nuclei, including the PC nuclei and the two types of prospective pronuclei. This suggested that cMTs were involved in the formation of a physical barrier, whose function may relate to sequestering and protecting the surviving nuclei from the major cytoplasm, where degeneration of extra-meiotic products occurs, another important nuclear event during the third prezygotic division.展开更多
Microtubules(MTs) are part of the cellular cytoskeleton and they play a role in many activities, such as cell division and maintenance of cell shape. In recent years, MTs have been thought to be involved in storing an...Microtubules(MTs) are part of the cellular cytoskeleton and they play a role in many activities, such as cell division and maintenance of cell shape. In recent years, MTs have been thought to be involved in storing and processing information.Several models have been developed to describe the information-processing ability of MTs. In these models, MTs are considered as a device that can transmit quantum information. However, MTs are affected by the "wet and warm" cellular environment, thus it is essential to calculate the decoherence time. Many researchers have attempted to calculate this parameter but the values that have been obtained vary markedly. Previous studies considered the cellular environment as a distant ion; however, this treatment is somewhat simplified. In this study, we develop a model to determine the decoherence time in neuronal MTs while considering the interaction effects of the neuronal fluid environment. The neuronal environment is considered as a plasmon reservoir. The coupling between MTs and neuronal environment occurs due to the interaction between dipoles and plasmon. The interaction Hamiltonian is derived by using the second quantization method, and the coupling coefficient is calculated. Finally, the decoherence time scale is estimated according to the interaction Hamiltonian.In this paper, the time scale of decoherence in MTs is approximately 1 fs-100 fs. This model may be used as a reference in other decoherence processes in biological tissues.展开更多
Among many types of proteinaceous filaments, microtubules （MTs） constitute the most rigid components of the cellular cytoskeleton. Microtubule dynamics is essential for many vital cellular processes such as intracel...Among many types of proteinaceous filaments, microtubules （MTs） constitute the most rigid components of the cellular cytoskeleton. Microtubule dynamics is essential for many vital cellular processes such as intracellular transport, metabolism, and cell division. We investigate the nonlinear dynamics of inhomogeneous microtubulin systems and the MT dynamics is found to be governed by a perturbed sine-Gordon equation. In the presence of various competing nonlinear inhomogeneities, it is shown that this nonlinear model can lead to the existence of kink and antikink solitons moving along MTs. We demonstrate kink-antikink pair collision in the framework of Hirota＇s bilinearization method. We conjecture that the collisions of the quanta of energy propagating in the form of kinks and antikinks may offer a new view of the mechanism of the retrograde and anterograde transport direction regulation of motor proteins in microtubulin systems.展开更多
We show how Jacobian elliptic functions （JEFs） can be used to solve ordinary differential equations （ODEs） describing the nonlinear dynamics of microtubules （MTs）. We demonstrate that only one of the JEFs can be...We show how Jacobian elliptic functions （JEFs） can be used to solve ordinary differential equations （ODEs） describing the nonlinear dynamics of microtubules （MTs）. We demonstrate that only one of the JEFs can be used while the remaining two do not represent the solutions of the crucial differential equation. We show that a kinkbtype soliton moves along MTs. Besides this solution, we also discuss a few more solutions that may or may not have physical meanings. Finally, we show what kind of ODE can be solved by using JEFs.展开更多
Co-localization of mierotubule (MT) and muscle myosin (MHO) myofibril immunofluoresoence in developing myotubes of chicken' skeletal muscle cultures was observed by using double staining of tubulin and MHO indirec...Co-localization of mierotubule (MT) and muscle myosin (MHO) myofibril immunofluoresoence in developing myotubes of chicken' skeletal muscle cultures was observed by using double staining of tubulin and MHO indirect immunofluorescence. 12-o-tetradeeanoyl-phorbol-13-acetate (TPA) selectively and reversibly blocks mycfibrillogenesis and alters the morphology of myotubes into myosacs where MTs are present in radiating pattern,when the arrested myogenic cells recover and start myofibrillogenesis after released from TPA, prior to the emergence of myofibrils, the pre-existing MTs become bipolarly aligned ooincidently with the tubular restoration of cell shape. Single nascent myofibrils overlapping with MTs extend into the base of growth tips where MTs go farther to the end of the tips. That MT might act as scaffold in guiding the bipolar elongation of the growing myofibrils was suggested. Taxol and ooloemid disturbed MT polymerization and disposition, and interfered with the normal spatial assembly of myofibrils in developing myotubes.展开更多
Photon counts were measured every 15 ms for 75 s from microtubule-enriched preparations (and nuclei) from mouse melanoma cells during baseline and after 2 min exposures to 1 μT magnetic fields. The magnetic fields we...Photon counts were measured every 15 ms for 75 s from microtubule-enriched preparations (and nuclei) from mouse melanoma cells during baseline and after 2 min exposures to 1 μT magnetic fields. The magnetic fields were generated from a circular array of solenoids and presented with accelerating or decelerating rotation velocities. The range of photon radiant flux density was in the order of 10-12 W·m-2. Microtubules preparations that had been exposed for only 2 min to a magnetic field configuration corresponding to the electric field pattern that induced long-term potentiation in neural tissue when applied as electric current displayed peaks of spectral power densities within 7 - 8 Hz, 9.5 Hz, 14 - 15 Hz, and 22 Hz bands. The major peak (9.4 Hz) bandwidth was approximately 0.1 Hz. While microtubule preparations exposed for 2 min to a 7 Hz sine-wave or in the absence of a field emitted an overall similar level of spectral power density, the peaks in power density were not present. Treatment with the LTP patterned fields, compared to the baseline or sine-wave fields primarily altered the frequency band in which the amplitude of the photon field was expressed. These results suggest that the photon emissions from microtubule preparations have the capacity to respond to specifically-patterned or geometric shapes of magnetic fields by altering spectral configurations rather than the absolute numbers of photons.展开更多
The specific diameter of microtubules was shown to be a primary solution when magnetic energy was set equal to Casimir energy. To discern if this spatial containment could be foci for information photon emissions were...The specific diameter of microtubules was shown to be a primary solution when magnetic energy was set equal to Casimir energy. To discern if this spatial containment could be foci for information photon emissions were measured from preparations of microtubules (MTs) while they were exposed in sequential 4 min intervals to various patterns of weak magnetic fields whose intensities ranged from 3 to 10 μT. Calculations from the median mass of a tubulin dimer, its summed charges and the applied magnetic field as well as the change in magnetic moment derived from the energy of the hydrogen line when applied to our experimental fields predicted a dynamic shift (Δf) between 0.03 and 0.21 Hz. Spectral power densities (SPD) indicated marked enhancements in photon numbers during periods of magnetic field exposures within the 7.6 to 7.8 Hz increment. The total SPD units for the shift were 10-18 to 10-17 J per s. Five of the eight patterns elicited a split spectrum of power within this range. Separate factor analyses of the SPDs of the serial values that composed the points of the actual field patterns indicated those that evoked the split-spectrum (Δf = 0.05 to 0.13 Hz) displayed significantly higher loadings on the same factor compared to those that did not. If this shift in photon energy reflects a phase modulation of the coherence frequency (8 MHz) of MTs, the increment of energy per MHz frequency would be within the energy of the neutral hydrogen line. These results suggest that the intrinsic structure or information from specific intensity magnetic fields when applied to MTs is reflected in photon energy densities vacillating around the fundamental Schumann Resonance that could be an interface between Casimir and magnetic sources.展开更多
Cytoskeletal microtubules have long been conjectured to have piezoelectric properties. They have been shown to behave as nematic liquid crystals which oscillate along their director axis due to the prevalent thermal f...Cytoskeletal microtubules have long been conjectured to have piezoelectric properties. They have been shown to behave as nematic liquid crystals which oscillate along their director axis due to the prevalent thermal fluctuations. In this work, we develop a theoretical model of the mechanics of microtubules in the cytosolic space based on the buckling of its structure due to these thermal fluctuations. This cytosolic space has been considered as a viscoelastic medium in which microtubule oscillations have been considered. As a result of resilience of cytosol and neighbouring filaments from the axial force due to thermal fluctuations, the surface traction acting laterally on the microtubule structure has been further used to elucidate its piezoelectric behaviour in vivo. After the piezoelectric properties induced by thermal fluctuations (in addition to the buckling) of microtubules have been discussed, we propose a model discussing how microtubules behave as energy harvesters and communicate via electromagnetic radiation, with each other, in an intracellular environment.展开更多
Pesticide plays a vital role in agricultural, industrial and residemial pest control. In recent years the ‘pesticide problem＇ has been the focus of public interest because these chemicals have a very important role ...Pesticide plays a vital role in agricultural, industrial and residemial pest control. In recent years the ‘pesticide problem＇ has been the focus of public interest because these chemicals have a very important role in agriculture but these chemicals also act like endocrine disruptor. Experiments were carried out on 12 weeks old mice with 30 ± 2 gm. b.w. Endosulfan were administered at 3 mg/kg b.w daily by gavage method for five weeks followed by selenium treatment at 10 μg/kg.b.w./day for five weeks. 9 ＋ 2 arrangment were clearly observed in control group mice with well structured dynein and nexin arm while Endosulfan treated group show depolymerised microtubule and 9 ＋ 1 arrangment with degenerated mitochondria. While selenium treated group shows restoration of 9 ＋ 2 arrangement of microtubule. It is evident from study that endosulfan causes depolymerisation of microtubule while selenium administered group show normal polymerized microtubule and restores normal fertility in mice.展开更多
In this work, the extended Jacobian elliptic function expansion method is used as the first time to evaluate the exact traveling wave solutions of nonlinear evolution equations. The validity and reliability of the met...In this work, the extended Jacobian elliptic function expansion method is used as the first time to evaluate the exact traveling wave solutions of nonlinear evolution equations. The validity and reliability of the method are tested by its applications to nano-solitons of ionic waves propagation along microtubules in living cells and nano-ionic currents of MTs which play an important role in biology.展开更多
Conformational states of microtubules and proteins have typical spatial-spectral arrangements of atoms, called spatial coherence, that are characteristic for building, homeostasis, decay, and apoptosis. Microtubules s...Conformational states of microtubules and proteins have typical spatial-spectral arrangements of atoms, called spatial coherence, that are characteristic for building, homeostasis, decay, and apoptosis. Microtubules show a principle of a self-organizing-synergetic structure called a Fröhlich-Bose-Einstein state. The spatial coherence of this state can be described by a toroidal quantum equation of coherence. In this space, microtubules and proteins have typical discrete frequency patterns. These frequencies comply with two proposed quantum wave equations of respective coherence (regulation) and decoherence (deregulation), that describe quantum entangled and disentangled states. The proposed equation of coherence shows the following typical scale invariant distribution of energy: E<sub>n</sub> = ħω<sub>ref </sub>2<sup>q</sup>3<sup>m</sup>. The proposed model supports quantum entanglement and is in line with the earlier published models of Fröhlich, Davydov, and Chern. A meta-analysis shows a semi-harmonic scale-invariant pattern for microtubules, stem cells, proteins, and EEG- and MEG-patterns. A fit has been found for about 50 different organizing frequencies and 5 disorganizing frequencies of measured microtubule frequencies that fit with the calculated values of the proposed quantum equations, which are positioned in a nested toroidal geometry. All measured and analysed frequencies of microtubules comply with the same energy distribution found for Bose-Einstein condensates. The overall results show a presence of an informational quantum code, a direct relation with the eigenfrequencies of microtubules, stem cells, DNA, and proteins, that supplies information to realize biological order in life cells and substantiates a collective Fröhlich-Bose-Einstein type of behaviour and further support the models of Tuszynski, Hameroff, Bandyopadhyay, Del Giudice and Vitiello, Katona, Pettini, and Pokorny.展开更多
Fully grown oocytes of Apostichopus japonicus have a cytoplasmic protuberance where the oocyte attaches to the follicle. The protuberance and the oolamina located on the opposite side of the oocyte indicate the animal...Fully grown oocytes of Apostichopus japonicus have a cytoplasmic protuberance where the oocyte attaches to the follicle. The protuberance and the oolamina located on the opposite side of the oocyte indicate the animal-vegetal axis. Two pre-meiotic centrosomes are anchored to the protuberance by microtubules between centrosomes and protuberance. After meiosis reinitiation induced by DTT solution, the germinal vesicle (GV) migrates towards the protuberance. The GV breaks down after it migrates to the oocyte membrane on the protuberance side. The protuberance then contracts back into the oocyte and the first polar body extrudes from the site of the former protuberance. The second polar body forms beneath the first. Thus the oocyte protuberance indicates the presumptive animal pole well before maturation of the oocyte.展开更多
The control of dissipation and amplification of solitary waves in an electrical model of a microtubule is demonstrated.This model consists of a shunt nonlinear resistance–capacitance(J(V)–C(V)) circuit and a series ...The control of dissipation and amplification of solitary waves in an electrical model of a microtubule is demonstrated.This model consists of a shunt nonlinear resistance–capacitance(J(V)–C(V)) circuit and a series resistance–inductance(R–L) circuit. Through linear dispersion analysis, two features of the network are found, that is, low bandpass and bandpass filter characteristics. The effects of the conductance’s parameter λ on the linear dispersion curve are also analyzed. It appears that an increase of λ induces a decrease(an increase) of the width of the bandpass filter for positive(negative) values of λ. By applying the reductive perturbation method, we derive the equation governing the dynamics of the modulated waves in the system. This equation is the well-known nonlinear Schr?dinger equation extended by a linear term proportional to a hybrid parameter σ, i.e., a dissipation or amplification coefficient. Based on this parameter, we successfully demonstrate the hybrid behavior(dissipation and amplification) of the system. The exact and approximate solitary wave solutions of the obtained equation are derived, and the effects of the coefficient σ on the characteristic parameters of these waves are investigated. Using the analytical solutions found, we show numerically that the waves that are propagated throughout the system can be dissipated, amplified, or remain stable depending on the network parameters. These results are not only in agreement with the analytical predictions, but also with the existing experimental results in the literature.展开更多
Motivated by the application of Winkler-like models for the buckling analysis of embedded carbon nanotubes, an orthotropic Winkler-like model is developed to study the buckling behavior of embedded cytoskeletal microt...Motivated by the application of Winkler-like models for the buckling analysis of embedded carbon nanotubes, an orthotropic Winkler-like model is developed to study the buckling behavior of embedded cytoskeletal microtubules within the cytoplasm. Experimental observations of the buckling of embedded cytoskeletal microtubules reveal that embedded microtubules bear a large compressive force as compared with free microtubules. The present theoretical model predicts that embedded microtubules in an elastic medium bear large compressive forces than free microtubules. The estimated critical pressure is in good agreement with the experimental values of the pressure-induced buckling of microtubules. Moreover, due to the mechanical coupling of microtubules with the surrounding elastic medium, the critical buckling force is increased considerably, which well explains the theory that the mechanical coupling of microtubules with an elastic medium increases compressive forces that microtubules can sustain. The model presented in the paper is a good approximation for the buckling analysis of embedded microtubules.展开更多
The distribution and morphology alterations of microfilaments and microtubules in the mesophyll cells and root-tip cells of wheat seedlings, which had been radiated by enhanced ultraviolet-B (10.08 KJ·m-2·d-...The distribution and morphology alterations of microfilaments and microtubules in the mesophyll cells and root-tip cells of wheat seedlings, which had been radiated by enhanced ultraviolet-B (10.08 KJ·m-2·d-1), were examined through the confocal laser scanning microscope (Model FV1000, Olympus, Japan). Microtubule was labeled with an indirect immunofluorescence staining method, and microfilament was labeled with fluorescein isothiocyanate-phalloidin (FITC-Ph) as probes. The results indicated that microtubules in mesophyll cells, compared with the controls, would be depolymerized significantly, and dispersed randomly showing some spots or short rods in the cytoplasm, under the enhanced UV-B radiation condition. The microtubule bundles tended to be diffused, and the fluorescence intensity of that significantly decreased. The distribution pattern of microfilaments, which usually arranged parallelly in control cells, was broken up by enhanced UV-B radiation. We further investigated the distribution and morphology of microtubules in root-tip cells during every stage of cell division, and found that these aberrant phenomena of microtubules were often associated with abnormal cell division. Our findings suggested that the distribution, morphology and structure of cytoskeleton in mesophyll cells and root-tip cells of wheat seedlings would be affected by enhanced UV-B radiation, which might be related to abnormal cell division caused by enhanced UV-B radiation as an extracellular signal.展开更多
基金supported by the Koeln Fortune Program/Faculty of Medicine,University of Cologne,the Alzheimer Forschung Initiative e.V.(grant#22039,to HZ)open-access funding from the DFG/GRC issued to the University of CologneAlzheimer Forschung Initiative e.V.for Open Access Publishing(a publication grant#P2401,to MAAK)。
文摘TAU is a microtubule-associated protein that promotes microtubule assembly and stability in the axon.TAU is missorted and aggregated in an array of diseases known as tauopathies.Microtubules are essential for neuronal function and regulated via a complex set of post-translational modifications,changes of which affect microtubule stability and dynamics,microtubule interaction with other proteins and cellular structures,and mediate recruitment of microtubule-severing enzymes.As impairment of microtubule dynamics causes neuronal dysfunction,we hypothesize cognitive impairment in human disease to be impacted by impairment of microtubule dynamics.We therefore aimed to study the effects of a disease-causing mutation of TAU(P301L)on the levels and localization of microtubule post-translational modifications indicative of microtubule stability and dynamics,to assess whether P301L-TAU causes stability-changing modifications to microtubules.To investigate TAU localization,phosphorylation,and effects on tubulin post-translational modifications,we expressed wild-type or P301L-TAU in human MAPT-KO induced pluripotent stem cell-derived neurons(i Neurons)and studied TAU in neurons in the hippocampus of mice transgenic for human P301L-TAU(p R5 mice).Human neurons expressing the longest TAU isoform(2N4R)with the P301L mutation showed increased TAU phosphorylation at the AT8,but not the p-Ser-262 epitope,and increased polyglutamylation and acetylation of microtubules compared with endogenous TAU-expressing neurons.P301L-TAU showed pronounced somatodendritic presence,but also successful axonal enrichment and a similar axodendritic distribution comparable to exogenously expressed 2N4R-wildtype-TAU.P301L-TAU-expressing hippocampal neurons in transgenic mice showed prominent missorting and tauopathy-typical AT8-phosphorylation of TAU and increased polyglutamylation,but reduced acetylation,of microtubules compared with non-transgenic littermates.In sum,P301L-TAU results in changes in microtubule PTMs,suggestive of impairment of microtubule stability.This is accompanied by missorting and aggregation of TAU in mice but not in i Neurons.Microtubule PTMs/impairment may be of key importance in tauopathies.
基金the North University of China for the support given for carrying out this work under projects from the National Natural Science Fundation of China(Nos.20571066 and 20871108)
文摘Fe（OH）3 precursor sol was prepared by a sol-gel method. The precursor sol was dipped onto the absorbent cotton, and gel was formed on the absorbent cotton template after the volatilization of moisture. Fe2O3 microtubules were synthesized after the process of self-propagation or calcination. The phase, morphology, and particle diameter of the samples were examined by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, and the magnetic properties of the samples were measured using a vibrating sample magnetometer （VSM）. The external diameters of Fe2O3 microtubules ranged between 8 and 13 μm, and the wall thicknesses ranged between 0.5 and 2 μm. The type of the calcination method plays a significant role in developing the Fe2O3 phase and the variation in the magnetic properties in the sol-gel template complexing method. γ-Fe2O3 was synthesized by a self-propagation method. However, α-Fe203 was synthesized after calcination at 400℃ for 2 h. The coercivity of the samples synthesized by calcination at 400℃ for 2 h after self-propagation was found to increase significantly, thereby presenting hard magnetic properties.
文摘Ran is an evolutionarily conserved eukaryotic GTPase that directly participates in cell cycle and whose loss affects many biological processes.We have identified cDNA of TaRAN/,a novel Ran GTPase homologous gene in wheat(Triticum aestivum L.cv.Jingdong No.1).The cytoplasmic microtu-bules play an important role in cytoplasmic organization,cell division,and the correct transmission of genetic information in fission yeast cell.Using the fission yeast system in vivo experiments,overexpression of TaRAN/produced defective spindle microtubules,probably resulting in chromosome missegregation we reported previously.The microtubules of antisense TaRANI yeast cells were physically disrupted.This suggested that TaRAN/plays a role in mitotic spindle assembly and microtubule integrity and stability.Ultrastructural analysis under transmission electron microscope(TEM)showed abnormal nuclear membranes in the overexpression TaRAN/yeast cells,abnormal vacuole structures and disorganized membranes in the antisense TaRANI yeast cells.These results suggested that TaRANI was essential for all nucleocytoplasmic transport events.
文摘This is a review paper describing recent findings about the physical properties of centriolar microtubules. Microtubules are the principal structures making up the centrioles. The centrioles in turn are the principal agents in cell duplication and division (mitosis). The microtubules are seen to be long hollow cylinders: approximately 400 nm in length, with a 24 nm outside diameter, and a 5 nm wall thickness. Within the centrioles, the microtubules are arranged into nine parallel sets of triplets—thus numbering 27 parallel cylinders per centriole. Each normal eukaryotic (human and animal) cell, not in mitosis, has two perpendicular centrioles connected at their proximal (base) ends. During mitosis, these two become four, resulting in a total of 108 centriolar microtubules. The structure of the microtubules themselves is found to consist of 13 parallel filaments making up the cylinder walls. The filaments are composed of approximately 40 and β-tubulin connected end-to-end with their proximal (base) ends anchored in γ-tubulin. The longitudinal vibrations of the filaments are believed to create an electro-magnetic field within the cell which plays an important role in mitosis.
基金National Natural Science Foundation of China(31071881)Research Development Foundation of Zhejiang A&F University(2009FK67).
文摘There are six micronuclear divisions during conjugation of Paramecium caudatum:three prezygotic and three postzygotic divisions.Four haploid nuclei are formed during the first two meiotic prezygotic divisions.Usually only one meiotic product is located in the paroral cone(PC)region at the completion of meiosis,which survives and divides mitotically to complete the third prezygotic division to yield a stationary and a migratory pronucleus.The remaining three located outside of the PC degenerate.The migratory pronuclei are then exchanged between two conjugants and fuse with the stationary pronuclei to form synkarya,which undergo three successive divisions(postzygotic divisions).However,little is known about the surviving mechanism of the PC nuclei.In the current study,stage-specific appearance of cytoplasmic microtubules(cMTs)was indicated during the third prezygotic division by immunofluorescence labeling with anti-alpha tubulin antibodies surrounding the surviving nuclei,including the PC nuclei and the two types of prospective pronuclei.This suggested that cMTs were involved in the formation of a physical barrier,whose function may relate to sequestering and protecting the surviving nuclei from the major cytoplasm,where degeneration of extra-meiotic products occurs,another important nuclear event during the third prezygotic division.
基金Foundation items： National Natural Science Foundation of China （31071881） Research Development Foundation of Zhejiang A ＆ F University （2009FK67）.
文摘There are six micronuclear divisions during conjugation of Paramecium caudatum： three prezygotic and three postzygotic divisions. Four haploid nuclei are formed during the first two meiotic prezygotic divisions. Usually only one meiotic product is located in the paroral cone （PC） region at the completion of meiosis, which survives and divides mitotically to complete the third prezygotic division to yield a stationary and a migratory pronucleus. The remaining three located outside of the PC degenerate. The migratory pronuclei are then exchanged between two conjugants and fuse with the stationary pronuclei to form synkarya, which undergo three successive divisions （postzygotic divisions）. However, little is known about the surviving mechanism of the PC nuclei. In the current study, stage-specific appearance of cytoplasmic microtubules （cMTs） was indicated during the third prezygotic division by immunofluorescence labeling with anti-alpha tubulin antibodies surrounding the surviving nuclei, including the PC nuclei and the two types of prospective pronuclei. This suggested that cMTs were involved in the formation of a physical barrier, whose function may relate to sequestering and protecting the surviving nuclei from the major cytoplasm, where degeneration of extra-meiotic products occurs, another important nuclear event during the third prezygotic division.
文摘Microtubules(MTs) are part of the cellular cytoskeleton and they play a role in many activities, such as cell division and maintenance of cell shape. In recent years, MTs have been thought to be involved in storing and processing information.Several models have been developed to describe the information-processing ability of MTs. In these models, MTs are considered as a device that can transmit quantum information. However, MTs are affected by the "wet and warm" cellular environment, thus it is essential to calculate the decoherence time. Many researchers have attempted to calculate this parameter but the values that have been obtained vary markedly. Previous studies considered the cellular environment as a distant ion; however, this treatment is somewhat simplified. In this study, we develop a model to determine the decoherence time in neuronal MTs while considering the interaction effects of the neuronal fluid environment. The neuronal environment is considered as a plasmon reservoir. The coupling between MTs and neuronal environment occurs due to the interaction between dipoles and plasmon. The interaction Hamiltonian is derived by using the second quantization method, and the coupling coefficient is calculated. Finally, the decoherence time scale is estimated according to the interaction Hamiltonian.In this paper, the time scale of decoherence in MTs is approximately 1 fs-100 fs. This model may be used as a reference in other decoherence processes in biological tissues.
基金supported by the Serbian Ministry of Education and Sciences(Grant No.Ⅲ45010)the URF from Periyar University,India+4 种基金the research award of UGCthe major research project of NBHM,Indiathe Young Scientist Research Award of BRNS,Indiathe Junior Associateship of ICTP,Italythe Rajiv Gandhi National Fellowship of UGC
文摘Among many types of proteinaceous filaments, microtubules （MTs） constitute the most rigid components of the cellular cytoskeleton. Microtubule dynamics is essential for many vital cellular processes such as intracellular transport, metabolism, and cell division. We investigate the nonlinear dynamics of inhomogeneous microtubulin systems and the MT dynamics is found to be governed by a perturbed sine-Gordon equation. In the presence of various competing nonlinear inhomogeneities, it is shown that this nonlinear model can lead to the existence of kink and antikink solitons moving along MTs. We demonstrate kink-antikink pair collision in the framework of Hirota＇s bilinearization method. We conjecture that the collisions of the quanta of energy propagating in the form of kinks and antikinks may offer a new view of the mechanism of the retrograde and anterograde transport direction regulation of motor proteins in microtubulin systems.
基金Project supported by Serbian Ministry of Education and Sciences (Grant No.III45010)UGC,NBHM,India (major research projects)+2 种基金BRNS,India (Young Scientist Research Award)ICTP,Italy (Junior Associateship)UGC (Rajiv Gandhi National Fellowship)
文摘We show how Jacobian elliptic functions （JEFs） can be used to solve ordinary differential equations （ODEs） describing the nonlinear dynamics of microtubules （MTs）. We demonstrate that only one of the JEFs can be used while the remaining two do not represent the solutions of the crucial differential equation. We show that a kinkbtype soliton moves along MTs. Besides this solution, we also discuss a few more solutions that may or may not have physical meanings. Finally, we show what kind of ODE can be solved by using JEFs.
文摘Co-localization of mierotubule (MT) and muscle myosin (MHO) myofibril immunofluoresoence in developing myotubes of chicken' skeletal muscle cultures was observed by using double staining of tubulin and MHO indirect immunofluorescence. 12-o-tetradeeanoyl-phorbol-13-acetate (TPA) selectively and reversibly blocks mycfibrillogenesis and alters the morphology of myotubes into myosacs where MTs are present in radiating pattern,when the arrested myogenic cells recover and start myofibrillogenesis after released from TPA, prior to the emergence of myofibrils, the pre-existing MTs become bipolarly aligned ooincidently with the tubular restoration of cell shape. Single nascent myofibrils overlapping with MTs extend into the base of growth tips where MTs go farther to the end of the tips. That MT might act as scaffold in guiding the bipolar elongation of the growing myofibrils was suggested. Taxol and ooloemid disturbed MT polymerization and disposition, and interfered with the normal spatial assembly of myofibrils in developing myotubes.
文摘Photon counts were measured every 15 ms for 75 s from microtubule-enriched preparations (and nuclei) from mouse melanoma cells during baseline and after 2 min exposures to 1 μT magnetic fields. The magnetic fields were generated from a circular array of solenoids and presented with accelerating or decelerating rotation velocities. The range of photon radiant flux density was in the order of 10-12 W·m-2. Microtubules preparations that had been exposed for only 2 min to a magnetic field configuration corresponding to the electric field pattern that induced long-term potentiation in neural tissue when applied as electric current displayed peaks of spectral power densities within 7 - 8 Hz, 9.5 Hz, 14 - 15 Hz, and 22 Hz bands. The major peak (9.4 Hz) bandwidth was approximately 0.1 Hz. While microtubule preparations exposed for 2 min to a 7 Hz sine-wave or in the absence of a field emitted an overall similar level of spectral power density, the peaks in power density were not present. Treatment with the LTP patterned fields, compared to the baseline or sine-wave fields primarily altered the frequency band in which the amplitude of the photon field was expressed. These results suggest that the photon emissions from microtubule preparations have the capacity to respond to specifically-patterned or geometric shapes of magnetic fields by altering spectral configurations rather than the absolute numbers of photons.
文摘The specific diameter of microtubules was shown to be a primary solution when magnetic energy was set equal to Casimir energy. To discern if this spatial containment could be foci for information photon emissions were measured from preparations of microtubules (MTs) while they were exposed in sequential 4 min intervals to various patterns of weak magnetic fields whose intensities ranged from 3 to 10 μT. Calculations from the median mass of a tubulin dimer, its summed charges and the applied magnetic field as well as the change in magnetic moment derived from the energy of the hydrogen line when applied to our experimental fields predicted a dynamic shift (Δf) between 0.03 and 0.21 Hz. Spectral power densities (SPD) indicated marked enhancements in photon numbers during periods of magnetic field exposures within the 7.6 to 7.8 Hz increment. The total SPD units for the shift were 10-18 to 10-17 J per s. Five of the eight patterns elicited a split spectrum of power within this range. Separate factor analyses of the SPDs of the serial values that composed the points of the actual field patterns indicated those that evoked the split-spectrum (Δf = 0.05 to 0.13 Hz) displayed significantly higher loadings on the same factor compared to those that did not. If this shift in photon energy reflects a phase modulation of the coherence frequency (8 MHz) of MTs, the increment of energy per MHz frequency would be within the energy of the neutral hydrogen line. These results suggest that the intrinsic structure or information from specific intensity magnetic fields when applied to MTs is reflected in photon energy densities vacillating around the fundamental Schumann Resonance that could be an interface between Casimir and magnetic sources.
文摘Cytoskeletal microtubules have long been conjectured to have piezoelectric properties. They have been shown to behave as nematic liquid crystals which oscillate along their director axis due to the prevalent thermal fluctuations. In this work, we develop a theoretical model of the mechanics of microtubules in the cytosolic space based on the buckling of its structure due to these thermal fluctuations. This cytosolic space has been considered as a viscoelastic medium in which microtubule oscillations have been considered. As a result of resilience of cytosol and neighbouring filaments from the axial force due to thermal fluctuations, the surface traction acting laterally on the microtubule structure has been further used to elucidate its piezoelectric behaviour in vivo. After the piezoelectric properties induced by thermal fluctuations (in addition to the buckling) of microtubules have been discussed, we propose a model discussing how microtubules behave as energy harvesters and communicate via electromagnetic radiation, with each other, in an intracellular environment.
文摘Pesticide plays a vital role in agricultural, industrial and residemial pest control. In recent years the ‘pesticide problem＇ has been the focus of public interest because these chemicals have a very important role in agriculture but these chemicals also act like endocrine disruptor. Experiments were carried out on 12 weeks old mice with 30 ± 2 gm. b.w. Endosulfan were administered at 3 mg/kg b.w daily by gavage method for five weeks followed by selenium treatment at 10 μg/kg.b.w./day for five weeks. 9 ＋ 2 arrangment were clearly observed in control group mice with well structured dynein and nexin arm while Endosulfan treated group show depolymerised microtubule and 9 ＋ 1 arrangment with degenerated mitochondria. While selenium treated group shows restoration of 9 ＋ 2 arrangement of microtubule. It is evident from study that endosulfan causes depolymerisation of microtubule while selenium administered group show normal polymerized microtubule and restores normal fertility in mice.
文摘In this work, the extended Jacobian elliptic function expansion method is used as the first time to evaluate the exact traveling wave solutions of nonlinear evolution equations. The validity and reliability of the method are tested by its applications to nano-solitons of ionic waves propagation along microtubules in living cells and nano-ionic currents of MTs which play an important role in biology.
文摘Conformational states of microtubules and proteins have typical spatial-spectral arrangements of atoms, called spatial coherence, that are characteristic for building, homeostasis, decay, and apoptosis. Microtubules show a principle of a self-organizing-synergetic structure called a Fröhlich-Bose-Einstein state. The spatial coherence of this state can be described by a toroidal quantum equation of coherence. In this space, microtubules and proteins have typical discrete frequency patterns. These frequencies comply with two proposed quantum wave equations of respective coherence (regulation) and decoherence (deregulation), that describe quantum entangled and disentangled states. The proposed equation of coherence shows the following typical scale invariant distribution of energy: E<sub>n</sub> = ħω<sub>ref </sub>2<sup>q</sup>3<sup>m</sup>. The proposed model supports quantum entanglement and is in line with the earlier published models of Fröhlich, Davydov, and Chern. A meta-analysis shows a semi-harmonic scale-invariant pattern for microtubules, stem cells, proteins, and EEG- and MEG-patterns. A fit has been found for about 50 different organizing frequencies and 5 disorganizing frequencies of measured microtubule frequencies that fit with the calculated values of the proposed quantum equations, which are positioned in a nested toroidal geometry. All measured and analysed frequencies of microtubules comply with the same energy distribution found for Bose-Einstein condensates. The overall results show a presence of an informational quantum code, a direct relation with the eigenfrequencies of microtubules, stem cells, DNA, and proteins, that supplies information to realize biological order in life cells and substantiates a collective Fröhlich-Bose-Einstein type of behaviour and further support the models of Tuszynski, Hameroff, Bandyopadhyay, Del Giudice and Vitiello, Katona, Pettini, and Pokorny.
基金Supported by National High Technology Research and Development Program of China (863 Program) (No. 2006AA10A411)National Programs for Science and Technology Development (No. 2006BAD09A01)
文摘Fully grown oocytes of Apostichopus japonicus have a cytoplasmic protuberance where the oocyte attaches to the follicle. The protuberance and the oolamina located on the opposite side of the oocyte indicate the animal-vegetal axis. Two pre-meiotic centrosomes are anchored to the protuberance by microtubules between centrosomes and protuberance. After meiosis reinitiation induced by DTT solution, the germinal vesicle (GV) migrates towards the protuberance. The GV breaks down after it migrates to the oocyte membrane on the protuberance side. The protuberance then contracts back into the oocyte and the first polar body extrudes from the site of the former protuberance. The second polar body forms beneath the first. Thus the oocyte protuberance indicates the presumptive animal pole well before maturation of the oocyte.
文摘The control of dissipation and amplification of solitary waves in an electrical model of a microtubule is demonstrated.This model consists of a shunt nonlinear resistance–capacitance(J(V)–C(V)) circuit and a series resistance–inductance(R–L) circuit. Through linear dispersion analysis, two features of the network are found, that is, low bandpass and bandpass filter characteristics. The effects of the conductance’s parameter λ on the linear dispersion curve are also analyzed. It appears that an increase of λ induces a decrease(an increase) of the width of the bandpass filter for positive(negative) values of λ. By applying the reductive perturbation method, we derive the equation governing the dynamics of the modulated waves in the system. This equation is the well-known nonlinear Schr?dinger equation extended by a linear term proportional to a hybrid parameter σ, i.e., a dissipation or amplification coefficient. Based on this parameter, we successfully demonstrate the hybrid behavior(dissipation and amplification) of the system. The exact and approximate solitary wave solutions of the obtained equation are derived, and the effects of the coefficient σ on the characteristic parameters of these waves are investigated. Using the analytical solutions found, we show numerically that the waves that are propagated throughout the system can be dissipated, amplified, or remain stable depending on the network parameters. These results are not only in agreement with the analytical predictions, but also with the existing experimental results in the literature.
基金supported by the National Natural Science Foundation of China (No. 10772105)the Shanghai Leading Academic Discipline Project (No. S30106)
文摘Motivated by the application of Winkler-like models for the buckling analysis of embedded carbon nanotubes, an orthotropic Winkler-like model is developed to study the buckling behavior of embedded cytoskeletal microtubules within the cytoplasm. Experimental observations of the buckling of embedded cytoskeletal microtubules reveal that embedded microtubules bear a large compressive force as compared with free microtubules. The present theoretical model predicts that embedded microtubules in an elastic medium bear large compressive forces than free microtubules. The estimated critical pressure is in good agreement with the experimental values of the pressure-induced buckling of microtubules. Moreover, due to the mechanical coupling of microtubules with the surrounding elastic medium, the critical buckling force is increased considerably, which well explains the theory that the mechanical coupling of microtubules with an elastic medium increases compressive forces that microtubules can sustain. The model presented in the paper is a good approximation for the buckling analysis of embedded microtubules.
文摘The distribution and morphology alterations of microfilaments and microtubules in the mesophyll cells and root-tip cells of wheat seedlings, which had been radiated by enhanced ultraviolet-B (10.08 KJ·m-2·d-1), were examined through the confocal laser scanning microscope (Model FV1000, Olympus, Japan). Microtubule was labeled with an indirect immunofluorescence staining method, and microfilament was labeled with fluorescein isothiocyanate-phalloidin (FITC-Ph) as probes. The results indicated that microtubules in mesophyll cells, compared with the controls, would be depolymerized significantly, and dispersed randomly showing some spots or short rods in the cytoplasm, under the enhanced UV-B radiation condition. The microtubule bundles tended to be diffused, and the fluorescence intensity of that significantly decreased. The distribution pattern of microfilaments, which usually arranged parallelly in control cells, was broken up by enhanced UV-B radiation. We further investigated the distribution and morphology of microtubules in root-tip cells during every stage of cell division, and found that these aberrant phenomena of microtubules were often associated with abnormal cell division. Our findings suggested that the distribution, morphology and structure of cytoskeleton in mesophyll cells and root-tip cells of wheat seedlings would be affected by enhanced UV-B radiation, which might be related to abnormal cell division caused by enhanced UV-B radiation as an extracellular signal.
