Nuclear Displacement Research Articles

Effect of the Seven Critical Elements on Life Recovery Following the Great East Japan Earthquake Disaster

The purpose of this study is to compare the effect size of seven critical elements on the life recovery in three prefectures, Iwate Prefecture, Miyagi Prefecture, and Fukushima Prefecture, which were severely damaged by the Great East Japan Earthquake Disaster. This study used the 2016 Tohoku Life Recovery Survey (N = 2111, response rate: 35.2%) for the analysis. The dataset was divided into each prefecture sample to compare the effects of seven critical elements on life recovery in the three prefectures. We obtained samples from Fukushima (N = 603), Iwate (N = 781), and Miyagi (N = 727). First, the distribution of life recovery by the three prefectures was confirmed. The results showed that those affected by the Great East Japan Earthquake disaster in Miyagi have a higher quality of life recovery. Finally, we compared the effects of seven critical elements on life recovery among the three prefectures’ models using GLM analysis. From the comparison of effect size (partial η2) and discussion, three points are shown. 1) In the Fukushima model, the effect size of physical/mental stress management and social ties was larger than in the other models. 2) The effects of 1) were caused by the experience of diaspora (nuclear disaster-caused displacement). 3) If forced diaspora can create good relationships with local people, the positive effects of social ties on life recovery for such people are larger than for those who have not experienced diaspora.

Natural reaction orbitals for characterizing electron transfer responsive to nuclear coordinate displacement.

The natural reaction orbital (NRO) is proposed as a new concept for analyzing chemical reactions from the viewpoint of the electronic theory. The pair of the occupied and virtual NROs that characterize electron transfer responsive to nuclear coordinate displacement along the reaction path is automatically extracted from the solution of the coupled-perturbed self-consistent-field (CPSCF) equation for the perturbation of the nuclear displacement. The NRO-based reaction analysis method is applied to several reactions. As a result, it is found that the sum of squares of the singular values, derived from the solution of the CPSCF equation, gives sharp peaks around the transition state structures and at the shoulders of the potential energy curve. The peaks around the transition states suggest a new physical meaning of transition state from the viewpoint of the electronic theory. Furthermore, the double peaks reveal the asynchronous processes of reactions, which are not always shown in potential energy analyses. Since the NRO-based reaction analysis method is universal and robust for describing reaction mechanisms from an electronic theory viewpoint, it is expected to lead to universal reaction analyses based on the electronic theory.

Squeezed into defection?—nuclear displacement by steatosis activates yes-associated protein (YAP) linked to oncogenic pathways in hepatocytes

Squeezed into defection?—nuclear displacement by steatosis activates yes-associated protein (YAP) linked to oncogenic pathways in hepatocytes

On the transfer of theoretical multipole parameters for restoring static electron density and revealing and treating atomic anharmonic motion. Features of chemical bonding in crystals of an isocyanuric acid derivative

The crystal and electronic structure of an isocyanuric acid derivative was studied by high-resolution single-crystal X-ray diffraction within the Hansen–Coppens multipole formalism. The observed deformation electron density shows signs of thermal smearing. The experimental picture meaningfully assigned to the consequences of unmodelled anharmonic atomic motion. Straightforward simultaneous refinement of all parameters, including Gram–Charlier coefficients, resulted in more significant distortion of apparent static electron density, even though the residual density became significantly flatter and more featureless. Further, the method of transferring multipole parameters from the model refined against theoretical structure factors as an initial guess was employed, followed by the subsequent block refinement of Gram–Charlier coefficients and the other parameters. This procedure allowed us to appropriately distinguish static electron density from the contaminant smearing effects of insufficiently accounted atomic motion. In particular, some covalent bonds and the weak π...π interaction between isocyanurate moieties were studied via the mutual penetration of atomic-like kinetic and electrostatic potential φ-basins with complementary atomic ρ-basins. Further, local electronic temperature was applied as an advanced descriptor for both covalent bonds and noncovalent interactions. Total probability density function (PDF) of nuclear displacement showed virtually no negative regions close to and around the atomic nuclei. The distribution of anharmonic PDF to a certain extent matched the residual electron density from the multipole model before anharmonic refinement. No signs of disordering of the sulfonyl group hidden in the modelled anharmonic motion were found in the PDF.

Structure and dynamics of electronically excited molecular systems

AbstractStructure and dynamics of electronic excited states of molecular systems is of contemporary interest to understand a rich variety of processes ranging from molecular spectroscopy to reaction dynamics. Developments over the past decades have established that coupling of electronic and nuclear motion is a generic feature in polyatomic molecular systems which causes a breakdown of the Born–Oppenheimer approximation. Such a coupling leads to conical intersections in non‐linear and glancing degeneracy in linear polyatomic systems. While the former case is quite general and has wide variances depending on the nature of the coupling on the symmetry ground, the latter one is specific to the linear systems having axial symmetry. The Jahn–Teller (JT) systems form a subclass in the former category and the latter category constitutes the Renner–Teller (RT) systems. These systems are characterized by high point group symmetry and orbital degeneracy. The latter splits upon distortion along suitable symmetry reducing nuclear displacement. The JT or the RT split component states may undergo symmetry allowed coupling among another JT or RT split component states or with some non‐degenerate states. These are termed as the pseudo‐JT and pseudo‐RT coupling, respectively. We have studied a variety of photo‐induced molecular processes with the aid of ab initio quantum chemistry and first principles quantum dynamics methods. We will document here some of the important developments in the field focusing on the work done on the JT and RT systems primarily in our own laboratory.This article is categorized under: Theoretical and Physical Chemistry > Spectroscopy Software > Quantum Chemistry Structure and Mechanism > Molecular Structures

Plasmacytoma and plasma cell myeloma affecting the jaws: A multi-institutional collaborative study.

Plasma cell neoplasms are characterized by the proliferation of a single clone of plasma cells with production of a monoclonal immunoglobulin. They can manifest as a single lesion (plasmacytoma) or as multiple lesions (multiple myeloma). Paraffin-embedded tissue blocks of patients microscopically diagnosed with plasma cell neoplasms in the jaws were retrieved from five pathology files. Data including clinical, radiographic, microscopic and immunohistochemical findings, treatment employed and follow-up status were retrieved from the pathology reports. Fifty-two cases were retrieved (mean age: 59.4years) without sex predilection. The mandible was the most affected site (67.3%), usually associated with pain and/or paresthesia (53.8%). Lesions in other bones besides the jaws were reported for 24 patients (46.2%). Radiographically, tumours usually presented as poorly defined osteolytic lesions with unilocular or multilocular images, while microscopy revealed diffuse proliferation of neoplastic plasma cells with nuclear displacement and abundant eosinophilic cytoplasm. Two cases were classified as anaplastic, and amyloid deposits were found in two other cases. Immunohistochemistry was positive for plasma cell markers and negative for CD20 and CD3, and monoclonality for kappa light chain predominated. The overall survival rate after 5years of follow-up was 26.6%. Plasma cell neoplasms are aggressive tumours with a poor prognosis and involvement of the jaws may be the first complaint of the patient. Thus, oral pathologists, head and neck surgeons and dentists should be aware of their clinical, radiographic and microscopic manifestations.

A study on core spontaneous imbibition behavior via nuclear magnetic resonance and displacement experiments

ABSTRACT Spontaneous imbibition is auniversal phenomenon in nature, which plays asignificant role in the two-phase flow of gas reservoirs with water. To quantitatively evaluate the spontaneous imbibition behavior of tight sandstone gas reservoirs, this paper conducts experiments on cores with different imbibition times based on core imbibition experiments, combined with nuclear magnetic resonance (NMR) and displacement experiments. In this paper, some significant findings were obtained by the imbibition experiments and NMR, which mainly included the T2 spectral response of spontaneous imbibition and the relationship between threshold pressure gradient (TPG) and water saturation. Homogenous propulsion of water through the macropores which are about 0.5 μm and the effective permeability has decreased by 70–80%. Displacement experiments proved that the threshold pressure phenomenon existed in the imbibition cores, the longer the imbibition time, the higher the water saturation, and the bigger TPG. After the dimensionless treatment, there is apositive linear correlation between TPG and water saturation. The results of this research play an important role in the study of percolation laws of agas reservoir with water and distribution characteristics of residual gas.

Construction of Lycetin Nanocarriers and Its Effect on the Proliferation and Apoptosis of Hepatocellular Carcinoma Cells by Regulating Nuclear Factor E2 Related Factor/Antioxidant Response Element Pathway.

This article explores the role of lysin nanocarriers in inducing apoptosis of human hepatocellular carcinoma cells and the possible molecular mechanisms. Cytotoxicity tests were performed in human fibroblast cell line MRC-5. Anti-cancer activity was tested in liver cancer cell lines HepG2 and HCCLM3. The results show that nanocarriers have a targeting effect on cancer cells, have high safety, and are good delivery vehicles for drugs. In this paper, the stability of lycopene and its degradation in aqueous solutions at different temperatures were studied, and the structure and mechanism of degradation products were determined. A new type of mesoporous silica nanocarrier was synthesized as a delivery carrier of lysin and its derivatives, which has a targeting effect on cancer cells and has a slow-release effect. Surface modification can improve circulation time and stability for future resistance in vivo. The cancer experiment laid the foundation. The results showed that the lysin nanocarriers inhibited the proliferation of HepG2 and HCCLM3 human liver cancer cells in a dependent manner. After the lysin nanocarriers acted on HepG2 human hepatocellular carcinoma cells for 48 h, the cell apoptosis rate was significantly increased by flow cytometry analysis. The carrier can significantly increase the levels of reactive oxygen species and malondialdehyde, and reduce the content of reduced glutathione and superoxide dismutase. At the same time, the lysin nanocarrier can down-regulate the expression of Nrf2 and HO-1 proteins, and inhibit the occurrence of Nrf2 Nuclear displacement. The lycopene nanocarrier inhibits the proliferation of HepG2, HCCLM3 human liver cancer cells, induces apoptosis, regulates the oxidative stress response in the cell, and regulates the Nrf2/AREE antioxidant signaling pathway, thereby promoting tumor cell apoptosis.

Escape from mitotic catastrophe by actin-dependent nuclear displacement in fission yeast

SummaryEukaryotic cells position the nucleus within the proper intracellular space, thereby safeguarding a variety of cellular processes. In fission yeast, the interphase nucleus is placed in the cell middle in a microtubule-dependent manner. By contrast, how the mitotic nucleus is positioned remains elusive. Here we show that several cell-cycle mutants that arrest in mitosis all displace the nucleus toward one end of the cell. Intriguingly, the actin cytoskeleton is responsible for nuclear movement. Time-lapse live imaging indicates that mitosis-specific F-actin cables possibly push the nucleus through direct interaction with the nuclear envelope, and subsequently actomyosin ring constriction further shifts the nucleus away from the center. This nuclear movement is beneficial, because if the nuclei were retained in the center, unseparated chromosomes would be intersected by the contractile actin ring and the septum, imposing the lethal cut phenotype. Thus, fission yeast escapes from mitotic catastrophe by means of actin-dependent nuclear movement.

A Python Algorithm to Analyze Inelastic Neutron Scattering Spectra Based on the y-Scale Formalism.

This paper presents a Python-based algorithm, named INSCorNorm, to correct the inelastic neutron scattering (INS) spectra for both sample and container self-shielding and to normalize the experimental spectral intensity to an absolute physical scale (barn/energy unit) facilitating the comparison with computer simulations and interpretation. The algorithm is benchmarked against INS measurements of ZrH2 performed on the TOSCA spectrometer at the ISIS Facility. We also apply the algorithm to the INS spectra from l-lysine, a system of broad interest in biology and medicine, and we discuss how corrected INS data provide an experimental benchmark for theoretical calculations of nuclear anisotropic displacement parameters in molecular systems. The total neutron sample cross section to use for the self-shielding corrections is discussed, as well as the best approach to derive experimentally the cross section at the VESUVIO spectrometer, together with the experimental value of the hydrogen nuclear mean kinetic energy, ⟨Ek⟩. The algorithm is made available to the neutron user community within the MANTID software.

Proposed Neuromorphological Mechanism of Dopamine-2 Receptor Blocker Model of Parkinsonism

Haloperidol is known to induce Parkinsonism by blocking dopamine-2 receptors (D2R). However, the mechanism in which Parkinsonism is induced is not well known. In this study, the mechanism of D2R inhibition model of Parkinsonism was proposed via neuromorphological findings observed in primary motor cortex and dorsal striatum. Sixteen female Wistar rats with average weight of 150 g were distributed into 4 groups (NS and -D2I, -D2II, -D2III). Parkinsonism was induced using 5 mg/kg, 10 mg/kg and 15 mg/kg of haloperidol for 21 days. Parkinsonism was accessed with the rotarod and parallel bar. Primary motor cortex (M1) and dorsal striatum (CPu) were processed and stained using haematoxylin and eosin (H&E) and Nissl stains. The density of Nissl bodies was examined with ImageJ software version 1.46. Data was analysed by one way analysis of variance and significant level was set at p ≤ 0.05. The results showed that prolong inhibition of D2R induces Parkinsonism by progressive deterioration of nuclear components, displacement and extrusion of nucleus leading to intracytoplasmic vacuoles in Betz cells of M1. This was projected to be associated with membrane damage. Neurofibrils were proposed to be lost following the numerous shrunken perikaryons observed in M1 and CPu. 70.6% of Nissl bodies were lost to high dose of haloperidol, this was purported to cause decline in protein synthesis and mitochondrial functions leading to decrease in synaptic plasticity and resulting in Parkinsonism.

Geometrical Evolution and Formation of the Photoproduct in the Cycloreversion Reaction of a Diarylethene Derivative Probed by Vibrational Spectroscopy.

The geometrical evolution of the reactant and formation of the photoproduct in the cycloreversion reaction of a diarylethene derivative were probed using time-resolved absorption spectroscopies in the visible to near-infrared and mid-infrared regions. The time-domain vibrational data in the visible region show that the initially formed Franck-Condon state is geometrically relaxed into the minimum in the excited state potential energy surface, concomitantly with the low-frequency coherent vibrations. Theoretical calculations indicate that the nuclear displacement in this coherent vibration is nearly parallel to that in the geometrical relaxation. Time-resolved mid-infrared spectroscopy directly detected the formation of the open-ring isomer with the same time constant as the decrease of the closed-ring isomer in the excited state minimum. This observation reveals that no detectable intermediate, in which the population is accumulated, is present between the excited closed-ring isomer and the open-ring isomer in the ground state.

Transcriptional, biochemical and histological alterations in adult zebrafish (Danio rerio) exposed to benzotriazole ultraviolet stabilizer-328

The occurrence of Benzotriazole Ultraviolet Stabilizer-328 (BUV-328) in different environmental and biological matrices is of immediate environmental concern. In the present study, we evaluated the toxicity of BUV-328 in zebrafish liver tissues to understand the role of oxidative damage in hepatotoxicity. Adult zebrafish were exposed to 0.01, 0.1 and 1 mg/L of BUV-328. At the end of 14, 28 and 42 days, liver tissues were examined for the responses of antioxidant enzymes, gene expression and histopathological alterations. The results indicated that superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities were elevated at concentrations of 0.1 and 1 mg/L on 14th and 28th day. Glutathione S-transferase (GST) activity and malondialdehyde (MDA) levels were elevated in all the treated groups. The transcriptional levels of genes encoding sod, cat, gpx and gst enzymes were increased at 14th day and then declined (except sod on 28th day). Moreover, transcription of cyp1a and hsp70 were up-regulated throughout the study period. Histopathological lesions such as hypertrophy, cellular and nuclear enlargement, cytoplasmic and nuclear degeneration, necrosis with pyknotic nuclei, lipid and cytoplasmic vacuolization and nuclear displacement to the periphery were found to be increased with the dose and exposure duration. In brief, our findings indicate that even a low dose of BUV-328 is toxic to induce oxidative stress and liver damage in zebrafish over a long period of exposure.

Oil charging model and controlling factors revealed by an online nuclear magnetic resonance (NMR) system

It is very difficult to simulate the charging process of crude oil under experimental conditions due to the low porosity and permeability of tight sandstone. However, simulations are important for revealing the mechanism of formation of tight oil and the oil-water distribution characteristics, as well as for enhancing the oil recovery efficiency. In this study, we established a new method, called nuclear magnetic resonance coupling displacement (NMR-DP), to simulate the tight oil charging process online. The NMR-DP method has the advantages of high precision, velocity, recyclability, and the ability to reflect the distribution of fluids in the micropores of a tight rock.We conducted a simulation experiment, involving the charging of crude oil into eight sandstone samples from Gaotaizi (in the Qijia-Longhupao area of the Songliao Basin). The results of this experiment were combined with those of microscopic measurements conducted on the pore structure (i.e., nuclear magnetic resonance, nitrogen adsorption, high-pressure and rate-controlled mercury injections, and micron-computed tomography). In this way, we clarified the charging process and its controlling factors (e.g., physical properties and wettability) and established a tight oil charging model. The results indicate that the oil charging saturation was controlled by several factors, including the charging pressure, physical properties, pore throat structure, and mineral composition of the rock. A smaller radius of the pore throat corresponded to a lower oil charging saturation and higher starting pressure gradient. The lower the content of clay and carbonate minerals, and the higher the content of feldspar mineral, the higher the oil saturation. Oil mainly occurred in the larger pores, while residual water mainly occurred in the smaller pores. The charging process was divided into four stages: an exponential rapid growth stage, a logarithmic slow-growth stage, a linear slow-growth stage, and a quasi-stationary stage. The method established in this paper is expected to be helpful for analyzing the distribution law of oil and water in tight sandstone areas, thereby aiding in the prediction of sweet spots and development of tight oil.

Role of the lattice in the light-induced insulator-to-metal transition in vanadium dioxide

VO$_{2}$ is a model material system which exhibits a metal to insulator transition at 67$^\circ$C. This holds potential for future ultrafast switching in memory devices, but typically requires a purely electronic process to avoid the slow lattice response. The role of lattice vibrations is thus important, but it is not well understood and it has been a long-standing source of controversy. We use a combination of ultrafast spectroscopy and ab initio quantum calculations to unveil the mechanism responsible for the transition. We identify an atypical Peierls vibrational mode which acts as a trigger for the transition. This rules out the long standing paradigm of a purely electronic Mott transition in VO$_{2}$; however, we found a new electron-phonon pathway for a purely reversible electronic transition in a true bi-stable fashion under specific conditions. This transition is very atypical, as it involves purely charge-like excitations and requires only small nuclear displacement. Our findings will prompt the design of future ultrafast electro-resistive non-volatile memory devices.

Effect of Shale Reservoir Characteristics on Shale Oil Movability in the Lower Third Member of the Shahejie Formation, Zhanhua Sag

AbstractTo reveal the effect of shale reservoir characteristics on the movability of shale oil and its action mechanism in the lower third member of the Shahejie Formation (Es3l), samples with different features were selected and analyzed using N2 adsorption, high‐pressure mercury injection capillary pressure (MICP), nuclear magnetic resonance (NMR), high‐speed centrifugation, and displacement image techniques. The results show that shale pore structure characteristics control shale oil movability directly. Movable oil saturation has a positive relationship with pore volume for radius > 2 μm, as larger pores often have higher movable oil saturation, indicating that movable oil is present in relatively larger pores. The main reasons for this are as follows. The relatively smaller pores often have oil‐wetting properties because of organic matter, which has an unfavorable effect on the flow of oil, while the relatively larger pores are often wetted by water, which is helpful to shale oil movability. The rich surface provided by the relatively smaller pores is beneficial to the adsorption of immovable oil. Meanwhile, the relatively larger pores create significant pore volume for movable oil. Moreover, the larger pores often have good pore connectivity. Pores and fractures are interconnected to form a complex fracture network, which provides a good permeability channel for shale oil flow. The smaller pores are mostly distributed separately; thus, they are not conducive to the flow of shale oil. The mineral composition and fabric macroscopically affect the movability of shale oil. Calcite plays an active role in shale oil movability by increasing the brittleness of shale and is more likely to form micro‐cracks under the same stress background. Clay does not utilize shale oil flow because of its large specific surface area and its block effect. The bedding structure increases the large‐scale storage space and improves the connectivity of pores at different scales, which is conducive to the movability of shale oil.

Haemoparasites in red-legged partridge (Alectoris rufa): first record of Haemoproteus sp. in Italy?

During a health survey in the Province of Alessandria (NW Italy) 267 free ranging red-legged partridge (Alectoris rufa; 137 males and 130 females) were captured in 2009 (n = 101), 2010 (n = 130) and 2011 (n = 36). After biometric data and blood samples collection, animals were released on site. Blood samples were used for the preparation of blood smears. A total of 1.5% of smears presented parasites with a light blue finely granular cytoplasm in red blood cells. The parasites were identified, on the basis of their morphology (no molecular identification was possible), as being Haemoproteus sp. juvenile forms. The infestation prevalence was 0.8% in 2010 and 8.3% in 2011. No parasite was observed in 2009. The size of the infested erythrocytes was not altered (P > 0.05) and the nuclear displacement ratio was 0.8 ± 0.2. All the birds were apparently in good health status. To our knowledge this is the first description of Haemoproteus sp. in red-legged partridge, and more in general in birds belonging to Galliformes Order in Italy.

First-principles study of large-amplitude dynamic Jahn–Teller effects in vanadium tetrafluoride

Transition metal tetrahalides are a class of highly symmetric molecules for which very few spectroscopic data exist. Exploratory ab initio calculations of electronic potential energy functions indicate that the equilibrium molecular geometries of the vanadium, niobium, and tantalum tetrafluorides (i.e., VF4, NbF4, and TaF4) exhibit strong distortions from the tetrahedral configuration in their electronic ground state (2E) and first excited state (2T2) along the nuclear displacement coordinates of e symmetry. The distortions result from the E × e and T2 × e Jahn-Teller (JT) effects, respectively. In addition, there are weaker distortions in the 2T2 state along the coordinates of t2 symmetry due to the T2 × t2 JT effect. The description of the large-amplitude dynamics induced by these JT effects requires the construction of JT Hamiltonians beyond the standard model of JT theory, which is based on Taylor expansions up to second order in normal-mode displacements. These higher-order JT Hamiltonians were constructed in this work by expansions of the electronic potentials of the title molecule in terms of symmetry invariant polynomials in symmetry-adapted nuclear displacement coordinates for the bending modes of VF4. A multi-configuration electronic structure method was employed to determine the coefficients of these high-order polynomial expansions from first principles. Using these large-amplitude Jahn-Teller Hamiltonians, the vibronic spectra of VF4 were computed. The spectra illustrate the effects of large-amplitude fluxional nonadiabatic dynamics due to exceptionally strong E × e and T2 × e JT couplings. In addition, the vibronic spectrum of the T2 × (e + t2) JT effect, including the bending mode of t2 symmetry, was computed. The spectrum displays strong inter-mode coupling effects exhibiting a vibronic structure, which is substantially different from that predicted by independent-mode approximation. These results represent the first ab initio study of dynamical Jahn-Teller effects in VF4.

Hepatic Steatosis in a Bullhead (Cottus gobio) Population from a High-Mountain Lake (Carnic Alps): Adaptation to an Extreme Ecosystem?

The aim of this study was to describe liver alterations observed in a bullhead (Cottus gobio) population from a high-mountain lake (Dimon Lake; 1857 m a.s.l.) located in Carnic Alps (Northeast Italy). Two fish sampling campaigns (summer and autumn) were performed in 2017 to explore the possible causes of this phenomenon. In addition, to investigate the typical liver features of C. gobio, control specimens were captured from Degano Creek in the same seasons. Total length, weight, and liver weight were recorded in fish from both sampling sites. In addition, Fulton’s condition factor (K) and hepatosomatic index (HSI) were calculated. Stomach contents were also analyzed. Liver from each specimen was sampled, and histological examination was carried out. Liver steatosis (L) (nuclear displacement and cytoplasm vacuolization) were histologically evaluated by assigning a semiquantitative severity score. A significant difference in L was found between Dimon Lake and Degano Creek in both summer (Mann–Whitney test; p = 0.0001) and autumn (Mann–Whitney test; p < 0.0001). Regarding HSI, a significant difference was also recorded between Dimon Lake and Degano Creek in summer (Mann–Whitney test; p < 0.0001) and also in autumn (Mann–Whitney test; p < 0.0001), but no seasonal change in K values was recorded between the two sites in both summer (Mann–Whitney test; p = 0.8589) and autumn (Mann–Whitney test; p = 0.6415). A significant positive correlation between HSI and L was found (ρS 0.573). The causes of this abnormality might be related to adaptation by the fish to the high-altitude environment, accumulating lipids in the liver to tackle the adverse season, which lasts for 6 months of the year. Nonetheless, our study does not preclude steatosis induced by a nearly exclusive chironomids diet in bullhead from Dimon Lake.

Simultaneous Regulation of Cytokinetic Furrow and Nucleus Positions by Cortical Tension Contributes to Proper DNA Segregation during Late Mitosis.

Coordinating mitotic spindle and cytokinetic furrow positioning is essential to ensure proper DNA segregation. Here, we present a novel mechanism, which corrects DNA segregation defects due to cytokinetic furrow mispositioning during the first division of C.elegans embryos. Correction of DNA segregation defects due to an abnormally anterior cytokinetic furrow relies on the concomitant and opposite displacements of the furrow and of the anterior nucleus toward the posterior and anterior poles of the embryo, respectively. It also coincides with cortical blebbing and an anteriorly directed cytoplasmic flow. Although microtubules contribute to nuclear displacement, relaxation of an excessive tension atthe anterior cortex plays a central role in the correction process and simultaneously regulates cytoplasmic flow as well as nuclear and furrow displacements. This work thus reveals the existence of a so-far uncharacterized correction mechanism, which is critical to correct DNA segregation defects due to cytokinetic furrow mispositioning.