Computational modelling and near-complete kinetochore tracking reveal how chromosome dynamics during cell division are co-ordinated in space and time

Mitotic chromosome segregation is a self-organising process that achieves high fidelity separation of 46 duplicated chromosomes into two daughter cells. Chromosomes must be captured by the microtubule-based spindle, aligned at the spindle equator where they undergo oscillatory motion (metaphase) and then pulled to opposite spindle poles (anaphase). These large and small-scale chromosome movements are driven by kinetochores, multi-protein machines, that link chromosomes to microtubules and generate directional forces. Through automated near-complete tracking of kinetochores at fine spatio-temporal resolution over long timescales, we produce a detailed atlas of kinetochore dynamics throughout metaphase and anaphase in human cells. We develop a hierarchical biophysical model of kinetochore dynamics and fit this model to 4D lattice light sheet experimental data using Bayesian inference. We demonstrate that location in the metaphase plate is the largest factor in the variation in kinetochore dynamics, exceeding the variation between cells, whilst within the spindle there is local spatio-temporal coordination between neighbouring kinetochores of directional switching events, kinetochore-fibre (K-fibre) polymerization/depolymerization state and the segregation of chromosomes. Thus, metaphase oscillations are robust to variation in the mechanical forces throughout the spindle, whilst the spindle environment couples kinetochore dynamics across the plate. Our methods provide a framework for detailed quantification of chromosome dynamics during mitosis in human cells.

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Small-scale spatio-temporal characteristics of accumulation rates in western Dronning Maud Land, Antarctica

Journal of Glaciology ◽

10.3189/002214308784886243 ◽

2008 ◽

Vol 54 (185) ◽

pp. 315-323 ◽

Cited By ~ 10

Author(s):

Helgard Anschütz ◽

Daniel Steinhage ◽

Olaf Eisen ◽

Hans Oerter ◽

Martin Horwath ◽

...

Keyword(s):

Accumulation Rate ◽

Temporal Variations ◽

Spatial Variations ◽

Small Scale ◽

Accumulation Rates ◽

Order Of Magnitude ◽

Dronning Maud Land ◽

Spatio Temporal ◽

Ground Penetrating ◽

Firn Core

AbstractSpatio-temporal variations of the recently determined accumulation rate are investigated using ground-penetrating radar (GPR) measurements and firn-core studies. The study area is located on Ritscherflya in western Dronning Maud Land, Antarctica, at an elevation range 1400–1560 m. Accumulation rates are derived from internal reflection horizons (IRHs), tracked with GPR, which are connected to a dated firn core. GPR-derived internal layer depths show small relief along a 22 km profile on an ice flowline. Average accumulation rates are about 190 kg m−2 a−1 (1980–2005) with spatial variability (1σ) of 5% along the GPR profile. The interannual variability obtained from four dated firn cores is one order of magnitude higher, showing 1σ standard deviations around 30%. Mean temporal variations of GPRderived accumulation rates are of the same magnitude or even higher than spatial variations. Temporal differences between 1980–90 and 1990–2005, obtained from two dated IRHs along the GPR profile, indicate temporally non-stationary processes, linked to spatial variations. Comparison with similarly obtained accumulation data from another coastal area in central Dronning Maud Land confirms this observation. Our results contribute to understanding spatio-temporal variations of the accumulation processes, necessary for the validation of satellite data (e.g. altimetry studies and gravity missions such as Gravity Recovery and Climate Experiment (GRACE)).

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Kalmag: a high spatio temporal model of the Geomagnetic field

10.5194/egusphere-egu21-7173 ◽

2021 ◽

Author(s):

Julien Baerenzung ◽

Matthias Holschneider

Keyword(s):

Geomagnetic Field ◽

Learning Algorithm ◽

Dynamical Evolution ◽

Small Scale ◽

Large Set ◽

The Core ◽

Resolution Model ◽

Auto Regressive ◽

Spatio Temporal ◽

Marine Vessels

We present a new high resolution model of the Geomagnetic field spanning the last 121 years. The model derives from a large set of data taken by low orbiting satellites, ground based observatories, marine vessels, airplane and during land surveys. It is obtained by combining a Kalman filter to a smoothing algorithm. Seven different magnetic sources are taken into account. Three of them are of internal origin. These are the core, the lithospheric &#160;and the induced / residual ionospheric fields. The other four sources are of external origin. They are composed by a close, a remote and a fluctuating magnetospheric fields as well as a source associated with field aligned currents. The dynamical evolution of each source is prescribed by an auto regressive process of either first or second order, except for the lithospheric field which is assumed to be static. The parameters of the processes were estimated through a machine learning algorithm with a sample of data taken by the low orbiting satellites of the CHAMP and Swarm missions. In this presentation we will mostly focus on the rapid variations of the core field, and the small scale lithospheric field.&#160; We will also discuss the nature of model uncertainties and the limitiations they imply.

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Spatio-temporal patterns and movement analysis of pigs from smallholder farms and implications for African swine fever spread, Limpopo province, South Africa

Onderstepoort Journal of Veterinary Research ◽

10.4102/ojvr.v82i1.795 ◽

2015 ◽

Vol 82 (1) ◽

Cited By ~ 4

Author(s):

Folorunso O. Fasina ◽

Japhta M. Mokoele ◽

B. Tom Spencer ◽

Leo A.M.L. Van Leengoed ◽

Yvette Bevis ◽

...

Keyword(s):

South Africa ◽

Smallholder Farmers ◽

Animal Health ◽

African Swine Fever ◽

Limpopo Province ◽

Small Scale ◽

Network Analyses ◽

Critical Control Points ◽

Spatio Temporal ◽

Disease Dispersal

Infectious and zoonotic disease outbreaks have been linked to increasing volumes of legal and illegal trade. Spatio-temporal and trade network analyses have been used to evaluate the risks associated with these challenges elsewhere, but few details are available for the pig sector in South Africa. Regarding pig diseases, Limpopo province is important as the greater part of the province falls within the African swine fever control area. Emerging small-scale pig farmers in Limpopo perceived pig production as an important means of improving their livelihood and an alternative investment. They engage in trading and marketing their products with a potential risk to animal health, because the preferred markets often facilitate potential longdistance spread and disease dispersal over broad geographic areas. In this study, we explored the interconnectedness of smallholder pig farmers in Limpopo, determined the weaknesses and critical control points, and projected interventions that policy makers can implement to reduce the risks to pig health. The geo-coordinates of surveyed farms were used to draw maps, links and networks. Predictive risks to pigs were determined through the analyses of trade networks, and the relationship to previous outbreaks of African swine fever was postulated. Auction points were identified as high-risk areas for the spread of animal diseases. Veterinary authorities should prioritise focused surveillance and diagnostic efforts in Limpopo. Early disease detection and prompt eradication should be targeted and messages promoting enhanced biosecurity to smallholder farmers are advocated. The system may also benefit from the restructuring of marketing and auction networks. Since geographic factors and networks can rapidly facilitate pig disease dispersal over large areas, a multi-disciplinary approach to understanding the complexities that exist around the animal disease epidemiology becomes mandatory.

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Build, measure, understand: Pupils contributing to meteorological measurement campaigns.

10.5194/ems2021-398 ◽

2021 ◽

Author(s):

Martin Göber ◽

Henning Rust ◽

Thomas Kox ◽

Bianca Wentzel ◽

Christopher Böttcher ◽

...

Keyword(s):

Weather Forecasting ◽

Cold Pool ◽

Small Scale ◽

Atmospheric Measurements ◽

High Resolution Data ◽

Representative Study ◽

Spatio Temporal ◽

Observed Damage ◽

Weather Risks ◽

Resolution Data

Voluntary weather measurements have a long tradition and the opportunities have recently expanded with that the advent of the Internet of Things. Atmospheric measurements are prototypical examples for the maker community and popular means to strengthen interest in STEM subjects. In two projects in Germany&#160; (in Brandenburg, within the FESSTVaL (Field Experiment on submesoscale spatio-temporal variability in Lindenberg) measurement campaign initiated by the Hans-Ertel-Center for Weather Research, and in Bavaria, in the KARE-Citizen Science&#160; project), we use a weather station to be assembled by pupils as a participatory vehicle to increase interest in and understanding of weather and climate, as well as of weather forecasting, and to generate high resolution data for research.The devices measure e.g. temperature, humidity, radiation, pressure and precipitation in the students' immediate environment. They can be placed in almost any location, since they operate independent of W-LAN and external power supply. The data is visualized directly via a web app. Students report weather impacts, such as observed damage or their own exposure to weather. Due to the pandemic, only a few dozens pupils were able to participate and building their devices had to be done with digital guidance and video support. Further online materials on understanding weather forecasting and its uncertainty were provided.Understanding of weather risks was surveyed before and after participation to detect any changes. Students were asked questions about thunderstorm, rain and heat events and climatic changes since 1880. The results show a good understanding of weather risks compared to a population of all ages representative study. In online workshops pupils together with the scientists scetched and discussed the influence of the placement of their stations on their measurements. Interesting meteorological phenomena were discovered in the dataset, e.g. a cold pool that can form during a thunderstorm and trigger new ones. Thus, our network of higher spatial and temporal resolution data collected by the pupils has the potential to study these small-scale phenomena in more detail than with professional networks of about 25 km spacing.

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Coastal Change Patterns from Time Series Clustering of Permanent Laser Scan Data

10.5194/esurf-2020-34 ◽

2020 ◽

Author(s):

Mieke Kuschnerus ◽

Roderik Lindenbergh ◽

Sander Vos

Keyword(s):

Time Series ◽

Laser Scanning ◽

Clustering Algorithm ◽

Coastal Areas ◽

Small Scale ◽

Temporal Data ◽

Agglomerative Clustering ◽

Data Set ◽

Deformation Processes ◽

Spatio Temporal

Abstract. Sandy coasts are constantly changing environments governed by complex interacting processes. Permanent laser scanning is a promising technique to monitor such coastal areas and support analysis of geomorphological deformation processes. This novel technique delivers 3D representations of a part of the coast at hourly temporal and centimetre spatial resolution and allows to observe small scale changes in elevation over extended periods of time. These observations have the potential to improve understanding and modelling of coastal deformation processes. However, to be of use to coastal researchers and coastal management, an efficient way to find and extract deformation processes from the large spatio-temporal data set is needed. In order to allow data mining in an automated way, we extract time series in elevation or range and use unsupervised learning algorithms to derive a partitioning of the observed area according to change patterns. We compare three well known clustering algorithms, k-means, agglomerative clustering and DBSCAN, and identify areas that undergo similar evolution during one month. We test if they fulfil our criteria for a suitable clustering algorithm on our exemplary data set. The three clustering methods are applied to time series of 30 epochs (during one month) extracted from a data set of daily scans covering a part of the coast at Kijkduin, the Netherlands. A small section of the beach, where a pile of sand was accumulated by a bulldozer is used to evaluate the performance of the algorithms against a ground truth. The k-means algorithm and agglomerative clustering deliver similar clusters, and both allow to identify a fixed number of dominant deformation processes in sandy coastal areas, such as sand accumulation by a bulldozer or erosion in the intertidal area. The DBSCAN algorithm finds clusters for only about 44 % of the area and turns out to be more suitable for the detection of outliers, caused for example by temporary objects on the beach. Our study provides a methodology to efficiently mine a spatio-temporal data set for predominant deformation patterns with the associated regions, where they occur.

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Mitochondrial Metabolism Determines the Spatio-Temporal Organization of Single F 1 F O ATP Synthase in Live Human Cells

Biophysical Journal ◽

10.1016/j.bpj.2016.11.035 ◽

2017 ◽

Vol 112 (3) ◽

pp. 3a

Author(s):

Karin Busch

Keyword(s):

Atp Synthase ◽

Human Cells ◽

Mitochondrial Metabolism ◽

Temporal Organization ◽

Spatio Temporal

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Estimating Precise Spatio-Temporal Distribution of Weather Condition Using Semi-Variogram in Small Scale Recreation Forest

Journal of the Korean Association of Geographic Information Studies ◽

10.11108/kagis.2015.18.3.063 ◽

2015 ◽

Vol 18 (3) ◽

pp. 63-75 ◽

Cited By ~ 3

Author(s):

Chul-Hee LIM

Keyword(s):

Weather Condition ◽

Temporal Distribution ◽

Small Scale ◽

Spatio Temporal

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The equatorial position of the metaphase plate ensures symmetric cell divisions

eLife ◽

10.7554/elife.05124 ◽

2015 ◽

Vol 4 ◽

Cited By ~ 12

Author(s):

Chia Huei Tan ◽

Ivana Gasic ◽

Sabina P Huber-Reggi ◽

Damian Dudka ◽

Marin Barisic ◽

...

Keyword(s):

Spindle Assembly Checkpoint ◽

Metaphase Plate ◽

Spindle Assembly ◽

Equatorial Position ◽

Asymmetric Cell Divisions ◽

Daughter Cells ◽

Cell Divisions ◽

Microtubule Stability ◽

Chromosome Alignment ◽

Metazoan Cell

Chromosome alignment in the middle of the bipolar spindle is a hallmark of metazoan cell divisions. When we offset the metaphase plate position by creating an asymmetric centriole distribution on each pole, we find that metaphase plates relocate to the middle of the spindle before anaphase. The spindle assembly checkpoint enables this centering mechanism by providing cells enough time to correct metaphase plate position. The checkpoint responds to unstable kinetochore–microtubule attachments resulting from an imbalance in microtubule stability between the two half-spindles in cells with an asymmetric centriole distribution. Inactivation of the checkpoint prior to metaphase plate centering leads to asymmetric cell divisions and daughter cells of unequal size; in contrast, if the checkpoint is inactivated after the metaphase plate has centered its position, symmetric cell divisions ensue. This indicates that the equatorial position of the metaphase plate is essential for symmetric cell divisions.

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