scholarly journals The kinesin-14, Ncd, drives a right-handed, helical motion of antiparallel microtubules around each other

2019 ◽  
Author(s):  
Aniruddha Mitra ◽  
Rojapriyadharshini Gandhimathi ◽  
Felix Ruhnow ◽  
Roman Renger ◽  
Stefan Diez
Keyword(s):  
Mitotic Spindle ◽  
Three Dimensional ◽  
Helical Motion ◽  
Flexible Filament ◽  
Torque Generation ◽  
Free Microtubules ◽  
20 Nm ◽  
The Impact

AbstractWithin the mitotic spindle, several kinesin motors crosslink and slide microtubules. While some of them (e.g. kinesin-5, kinesin-8 and kinesin-14) have been shown to exhibit sideways components in their step cycles, the impact of the resulting off-axis power strokes on motility and force generation in the spindle has not been investigated so far. Here, we develop and utilize a novel three-dimensional in vitro motility assay to explore the kinesin-14, Ncd, driven sliding of crosslinked, fluorescently-labeled microtubules. We find that free microtubules, sliding in an antiparallel orientation on microtubules suspended between nanofabricated ridges, not only rotate around their own axis but also move around the suspended microtubules with right-handed helical trajectories. In contrast, microtubules crosslinked in parallel orientation are static with neither longitudinal nor helical motion. Further, our technique allows us to measure the in situ spatial extension of the motors between the crosslinked microtubules to be about 20 nm. We argue that the capability of microtubule-crosslinking kinesins to cause helical motion of microtubules around each other allows for flexible filament organization, roadblock circumvention and torque generation in the mitotic spindle.

scholarly journals Kinesin-14 motors drive a right-handed helical motion of antiparallel microtubules around each other

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Aniruddha Mitra ◽  
Laura Meißner ◽  
Rojapriyadharshini Gandhimathi ◽  
Roman Renger ◽  
Felix Ruhnow ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Three Dimensional ◽  
Helical Motion ◽  
In Vitro Motility Assay ◽  
In Vitro Motility ◽  
Torque Generation ◽  
Free Microtubules ◽  
20 Nm

Abstract Within the mitotic spindle, kinesin motors cross-link and slide overlapping microtubules. Some of these motors exhibit off-axis power strokes, but their impact on motility and force generation in microtubule overlaps has not been investigated. Here, we develop and utilize a three-dimensional in vitro motility assay to explore kinesin-14, Ncd, driven sliding of cross-linked microtubules. We observe that free microtubules, sliding on suspended microtubules, not only rotate around their own axis but also move around the suspended microtubules with right-handed helical trajectories. Importantly, the associated torque is large enough to cause microtubule twisting and coiling. Further, our technique allows us to measure the in situ spatial extension of the motors between cross-linked microtubules to be about 20 nm. We argue that the capability of microtubule-crosslinking kinesins to cause helical motion of overlapping microtubules around each other allows for flexible filament organization, roadblock circumvention and torque generation in the mitotic spindle.

Correlated Studies of Cellular Interactions Using TEM, Freeze Etching, and SEM

1974 ◽  
Vol 32 ◽  
pp. 320-321
Author(s):  
J. P. Revel
Keyword(s):  
Developmental Stages ◽  
Three Dimensional ◽  
Cell Movement ◽  
Cellular Interactions ◽  
Serial Sections ◽  
Cell Sheets ◽  
Freeze Etching ◽  
Early Developmental

Movement of individual cells or of cell sheets and complex patterns of folding play a prominent role in the early developmental stages of the embryo. Our understanding of these processes is based on three- dimensional reconstructions laboriously prepared from serial sections, and from autoradiographic and other studies. Many concepts have also evolved from extrapolation of investigations of cell movement carried out in vitro. The scanning electron microscope now allows us to examine some of these events in situ. It is possible to prepare dissections of embryos and even of tissues of adult animals which reveal existing relationships between various structures more readily than used to be possible vithout an SEM.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

scholarly journals O-Vanillin Attenuates the TLR2 Mediated Tumor-Promoting Phenotype of Microglia

2020 ◽  
Vol 21 (8) ◽  
pp. 2959
Author(s):  
Paul Triller ◽  
Julia Bachorz ◽  
Michael Synowitz ◽  
Helmut Kettenmann ◽  
Darko Markovic
Keyword(s):  
Malignant Gliomas ◽  
Experimental Models ◽  
Brain Macrophages ◽  
Human Microglia ◽  
Glioma Growth ◽  
Toll Like Receptor 2 ◽  
Brain Slice Cultures ◽  
The Impact

Malignant gliomas are primary brain tumors with poor prognoses. These tumors are infiltrated by brain intrinsic microglia and peripheral monocytes which promote glioma cell invasion. In our previous studies, we discovered that the activation of Toll-like receptor 2 (TLR2) on microglia/brain macrophages converts them into a protumorigenic phenotype through the induction of matrix metalloproteinases (MMP) 9 and 14. In the present study, we used in vitro and in situ microglia-glioma interaction experimental models to test the impact of a novel inhibitor of TLR 2, ortho vanillin (O-Vanillin) to block TLR2 mediated microglia protumorigenic phenotype. We demonstrate that O-Vanillin inhibits the TLR2 mediated upregulation of MMP 9, MMP 14, IL 6 and iNOS expression. Similarly, the glioma supernatant induced MMP 9 and MMP 14 expression in murine and human microglia is abrogated by O-Vanillin treatment. O-Vanillin is not toxic for microglia, astrocytes or oligodendrocytes. Glioma growth in murine brain slice cultures is significantly reduced after treatment with O-Vanillin, and this reduced glioma growth depends on the presence of microglia. In addition, we also found that O-Vanillin inhibited the glioma induced proliferation of murine primary microglia. In summary, O-Vanillin attenuates the pro-tumorigenic phenotype of microglia/brain macrophages and thus qualifies as a candidate for glioma therapy.

scholarly journals Doxorubicin-Induced Translocation of mtDNA into the Nuclear Genome of Human Lymphocytes Detected Using a Molecular-Cytogenetic Approach

2020 ◽  
Vol 21 (20) ◽  
pp. 7690
Author(s):  
Tigran Harutyunyan ◽  
Ahmed Al-Rikabi ◽  
Anzhela Sargsyan ◽  
Galina Hovhannisyan ◽  
Rouben Aroutiounian ◽  
...  
Keyword(s):  
Human Lymphocytes ◽  
Nuclear Genome ◽  
Biological Phenomenon ◽  
Molecular Cytogenetic ◽  
Chromosome Breaks ◽  
Pathological Conditions ◽  
The Impact ◽  
In Vitro Treatment

Translocation of mtDNA in the nuclear genome is an ongoing process that contributes to the development of pathological conditions in humans. However, the causal factors of this biological phenomenon in human cells are poorly studied. Here we analyzed mtDNA insertions in the nuclear genome of human lymphocytes after in vitro treatment with doxorubicin (DOX) using a fluorescence in situ hybridization (FISH) technique. The number of mtDNA insertions positively correlated with the number of DOX-induced micronuclei, suggesting that DOX-induced chromosome breaks contribute to insertion events. Analysis of the odds ratios (OR) revealed that DOX at concentrations of 0.025 and 0.035 µg/mL significantly increases the rate of mtDNA insertions (OR: 3.53 (95% CI: 1.42–8.76, p < 0.05) and 3.02 (95% CI: 1.19–7.62, p < 0.05), respectively). Analysis of the distribution of mtDNA insertions in the genome revealed that DOX-induced mtDNA insertions are more frequent in larger chromosomes, which are more prone to the damaging action of DOX. Overall, our data suggest that DOX-induced chromosome damage can be a causal factor for insertions of mtDNA in the nuclear genome of human lymphocytes. It can be assumed that the impact of a large number of external and internal mutagenic factors contributes significantly to the origin and amount of mtDNA in nuclear genomes.

scholarly journals Topology of Chromosomes 18 and X in Human Blastomeres from 3- to 4-Day-old Embryos

2005 ◽  
Vol 53 (3) ◽  
pp. 273-276 ◽  
Author(s):  
Jan Diblík ◽  
Milan Macek ◽  
Maria-Cristina Magli ◽  
Roman Krejčí ◽  
Luca Gianaroli
Keyword(s):  
Three Dimensional ◽  
Dimensional Sphere ◽  
Chromosome X ◽  
Sphere Model ◽  
Chromosome 18 ◽  
Vitro Fertilization ◽  
Signal Distribution ◽  
Human In Vitro Fertilization

The positions of chromosomes 18 and X fluorescence in situ hybridization signals were analyzed in blastomeres generated from human in vitro fertilization 3- to 4-day-old embryos after preimplantation screening of aneuploidy of chromosomes 13, 16, 18, 21, 22, X, and Y. Fluorescent signal localization compared with a three-dimensional sphere model of random signal distribution revealed significant differences, providing evidence of peripheral localization of chromosome 18 in aneuploid ( p=0.0013) and aneuploid/euploid blastomeres ( p=0.0011). No differences were found in localization of chromosome 18 in euploid and in chromosome X in euploid and aneuploid blastomeres.

scholarly journals The Secretome Analysis of Activated Human Renal Fibroblasts Revealed Beneficial Effect of the Modulation of the Secreted Peptidyl-Prolyl Cis-Trans Isomerase A in Kidney Fibrosis

Cells ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1724
Author(s):  
Gry H. Dihazi ◽  
Marwa Eltoweissy ◽  
Olaf Jahn ◽  
Björn Tampe ◽  
Michael Zeisberg ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Renal Fibrosis ◽  
Cell Activation ◽  
Cell Transformation ◽  
Three Dimensional ◽  
3D Cell Culture ◽  
Kidney Fibrosis ◽  
Matrix Accumulation ◽  
The Impact

The secretome is an important mediator in the permanent process of reciprocity between cells and their environment. Components of secretome are involved in a large number of physiological mechanisms including differentiation, migration, and extracellular matrix modulation. Alteration in secretome composition may therefore trigger cell transformation, inflammation, and diseases. In the kidney, aberrant protein secretion plays a central role in cell activation and transition and in promoting renal fibrosis onset and progression. Using comparative proteomic analyses, we investigated in the present study the impact of cell transition on renal fibroblast cells secretome. Human renal cell lines were stimulated with profibrotic hormones and cytokines, and alterations in secretome were investigated using proteomic approaches. We identified protein signatures specific for the fibrotic phenotype and investigated the impact of modeling secretome proteins on extra cellular matrix accumulation. The secretion of peptidyl-prolyl cis-trans isomerase A (PPIA) was demonstrated to be associated with fibrosis phenotype. We showed that the in-vitro inhibition of PPIA with ciclosporin A (CsA) resulted in downregulation of PPIA and fibronectin (FN1) expression and significantly reduced their secretion. Knockdown studies of PPIA in a three-dimensional (3D) cell culture model significantly impaired the secretion and accumulation of the extracellular matrix (ECM), suggesting a positive therapeutic effect on renal fibrosis progression.

scholarly journals On the ability of chemical transport models to simulate the vertical structure of the N<sub>2</sub>O, NO<sub>2</sub> and HNO<sub>3</sub> species in the mid-latitude stratosphere

2005 ◽  
Vol 5 (6) ◽  
pp. 12373-12401
Author(s):  
G. Berthet ◽  
N. Huret ◽  
F. Lefèvre ◽  
G. Moreau ◽  
C. Robert ◽  
...  
Keyword(s):  
Transport Model ◽  
Three Dimensional ◽  
Chemical Transport ◽  
Chemical Transport Model ◽  
Transport Models ◽  
One Dimensional ◽  
Chemical Transport Models ◽  
Dimensional Version ◽  
The Impact

Abstract. In this paper we study the impact of the modelling of N2O on the simulation of NO2 and HNO3 by comparing in situ vertical profiles measured at mid-latitudes with the results of the Reprobus 3-D CTM (Three-dimensional Chemical Transport Model) computed with the kinetic parameters from the JPL recommendation in 2002. The analysis of the measured in situ profile of N2O shows particular features indicating different air mass origins. The measured N2O, NO2 and HNO3 profiles are not satisfyingly reproduced by the CTM when computed using the current 6-hourly ECMWF operational analysis. Improving the simulation of N2O transport allows us to calculate quantities of NO2 and HNO3 in reasonable agreement with observations. This is achieved using 3-hourly winds obtained from ECMWF forecasts. The best agreement is obtained by constraining a one-dimensional version of the model with the observed N2O. This study shows that modelling the NOy partitioning with better accuracy relies at least on a correct simulation of N2O and thus of total NOy.

scholarly journals Chemical Composition, In Vitro and In Situ Antimicrobial and Antibiofilm Activities of Syzygium aromaticum (Clove) Essential Oil

Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2185
Author(s):  
Miroslava Kačániová ◽  
Lucia Galovičová ◽  
Petra Borotová ◽  
Veronika Valková ◽  
Hana Ďúranová ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Essential Oil ◽  
Mass Spectra ◽  
Control Sample ◽  
Antibiofilm Activity ◽  
Syzygium Aromaticum ◽  
Food Preservatives ◽  
The Impact

The essential oil of Syzygium (S.) aromaticum (CEO) is known for its good biological activity. The aim of the research was to evaluate in vitro and in situ antimicrobial and antibiofilm activity of the essential oil produced in Slovakia. The main components of CEO were eugenol 82.4% and (E)-caryophyllene 14.0%. The antimicrobial activity was either weak or very strong with inhibition zones ranging from 4.67 to 15.78 mm in gram-positive and gram-negative bacteria and from 8.22 to 18.56 mm in yeasts and fungi. Among the tested bacteria and fungi, the lowest values of MIC were determined for Staphylococcus (S.) aureus and Penicillium (P.) expansum, respectively. The vapor phase of CEO inhibited the growth of the microscopic filamentous fungi of the genus Penicillium when tested in situ on bread. The strongest effect of mycelia inhibition in a bread model was observed against P. expansum at concentrations of 250 and 500 μL/mL. The best antimicrobial activity of CEO in the carrot model was found against P. chrysosenum. Differences between the mass spectra of Bacillus (B.) subtilis biofilms on the tested surfaces (wood, glass) and the control sample were noted from the seventh day of culture. There were some changes in mass spectra of Stenotrophomonas (S.) maltophilia, which were observed in both experimental groups from the fifth day of culture. These findings confirmed the impact of CEO on the protein structure of older biofilms. The findings indicate that, besides being safe and sensorially attractive, S. aromaticum has antimicrobial activity, which makes it a potential substitute for chemical food preservatives.

scholarly journals RE-EVALUATION OF THE STRETCH SENSITIVITY HYPOTHESIS OF CRUSTACEAN HEARTS: HYPOXIA, NOT LACK OF STRETCH, CAUSES REDUCTION IN HEART RATE OF ISOLATED HEARTS

1993 ◽  
Vol 176 (1) ◽  
pp. 223-232
Author(s):  
J. L. Wilkens
Keyword(s):  
Heart Rate ◽  
Isolated Heart ◽  
Carcinus Maenas ◽  
Three Dimensional ◽  
Decapod Crustacean ◽  
Diastolic Filling ◽  
Elastic Recoil ◽  
Isolated Hearts

Decapod crustacean hearts are suspended by a three-dimensional array of alary ligaments. These ligaments are stretched during systole; diastolic filling via the ostia occurs as the ventricle is stretched by ligamental elastic recoil. There is no direct venous return to the hearts in these animals. In the present study, an isolated heart preparation with intact ligaments, hereafter called in situ, was used to evaluate the effects of artificially induced stretch on heart rate. Strongly beating in situ neurogenic hearts of the crab Carcinus maenas responded to direct perfusion of the ventricle with oxygenated saline and the attendant augmentation of natural stretch with a small increase in heart rate (fh); however, fh was well maintained for up to 15 min after eliminating stretch by cutting the alary ligaments. In contrast to crabs, high rates of artificial perfusion usually depressed fh in crayfish hearts. Crab heart rate falls during hypoxia and this is readily reversed by even low rates of perfusion with oxygenated saline. It is concluded that the gradual decline in fh of totally isolated in vitro hearts arises from the deepening intraventricular hypoxia experienced by the cardiac ganglion.

Sign in / Sign up

Export Citation Format

Share Document