scholarly journals Optical flow analysis reveals that Kinesin-mediated advection impacts the orientation of microtubules in the Drosophila oocyte

2020 ◽  
Vol 31 (12) ◽  
pp. 1246-1258 ◽  
Author(s):  
Maik Drechsler ◽  
Lukas F. Lang ◽  
Layla Al-Khatib ◽  
Hendrik Dirks ◽  
Martin Burger ◽  
...  
Keyword(s):  
Motion Estimation ◽  
Optical Flow ◽  
Cytoplasmic Streaming ◽  
Flow Analysis ◽  
Flow Motion ◽  
A Cell

Here we introduce an optical flow motion estimation approach to study microtubule (MT) orientation in the Drosophila oocyte, a cell displaying substantial cytoplasmic streaming. We show that MT polarity is affected by the regime of these flows and, furthermore, that the presence of flows is necessary for MTs to adopt their proper polarity.

scholarly journals Optical flow analysis reveals that Kinesin-mediated advection impacts on the orientation of microtubules in the Drosophila oocyte

2019 ◽  
Author(s):  
Maik Drechsler ◽  
Lukas F. Lang ◽  
Layla Al-Khatib ◽  
Hendrik Dirks ◽  
Martin Burger ◽  
...  
Keyword(s):  
Optical Flow ◽  
Cytoplasmic Streaming ◽  
Flow Analysis ◽  
Growth Direction ◽  
Model Systems ◽  
Microtubule Orientation ◽  
A Cell ◽  
The Impact

ABSTRACTThe orientation of microtubule networks is exploited by motors to deliver cargoes to specific intracellular destinations, and is thus essential for cell polarity and function. Reconstituted in vitro systems have largely contributed to understanding the molecular framework regulating the behavior of microtubule filaments. In cells however, microtubules are exposed to various biomechanical forces that might impact on their orientation, but little is known about it. Oocytes, which display forceful cytoplasmic streaming, are excellent model systems to study the impact of motion forces on cytoskeletons in vivo. Here we implement variational optical flow analysis as a new approach to analyze the polarity of microtubules in the Drosophila oocyte, a cell that displays distinct Kinesin-dependent streaming. After validating the method as robust for describing microtubule orientation from confocal movies, we find that increasing the speed of flows results in aberrant plus end growth direction. Furthermore, we find that in oocytes where Kinesin is unable to induce cytoplasmic streaming, the growth direction of microtubule plus ends is also altered. These findings lead us to propose that cytoplasmic streaming - and thus motion by advection – contributes to the correct orientation of MTs in vivo. Finally, we propose a possible mechanism for a specialised cytoplasmic actin network (the actin mesh) to act as a regulator of flow speeds; to counteract the recruitment of Kinesin to microtubules.HIGHLIGHT SUMMARYCytoskeletal networks do not exist in isolation, but experience crowded and dynamic intracellular environments. However, microtubule-environment interactions are not well understood, and such system-environment interactions are an unresolved question in biology that demands bridging across disciplines. Here we introduce an optical flow motion estimation approach to study microtubule orientation in the Drosophila oocyte, a cell displaying substantial cytoplasmic streaming. We show that microtubule polarity is affected by the regime of these flows, and furthermore, that the presence of flows is necessary for MTs to adopt their proper polarity. With these findings we are contributing to further understanding how microtubules organize in their impacting natural environment.

A robust optical flow motion estimation and correction method for IRT imaging in brain surgery

2020 ◽  
pp. 1-26
Author(s):  
Yahya Moshaei-Nezhad ◽  
Juliane Müller ◽  
Christian Schnabel ◽  
Matthias Kirsch ◽  
Ronald Tetzlaff
Keyword(s):  
Motion Estimation ◽  
Optical Flow ◽  
Correction Method ◽  
Brain Surgery ◽  
Flow Motion ◽  
Estimation And Correction

A Three-Dimensional Viscous Transonic Inverse Design Method

2000 ◽  
Author(s):  
W. T. Tiow ◽  
M. Zangeneh
Keyword(s):  
Design Method ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Viscous Effects ◽  
Flow Equations ◽  
Flow Solution ◽  
Turbomachinery Blades ◽  
A Cell ◽  
Inverse Design Method ◽  
Euler Solver

The development and application of a three-dimensional inverse methodology is presented for the design of turbomachinery blades. The method is based on the mass-averaged swirl, rV~θ distribution and computes the necessary blade changes directly from the discrepancies between the target and initial distributions. The flow solution and blade modification converge simultaneously giving the final blade geometry and the corresponding steady state flow solution. The flow analysis is performed using a cell-vertex finite volume time-marching algorithm employing the multistage Runge-Kutta integrator in conjunction with accelerating techniques (local time stepping and grid sequencing). To account for viscous effects, dissipative forces are included in the Euler solver using the log-law and mixing length models. The design method can be used with any existing solver solving the same flow equations without any modifications to the blade surface wall boundary condition. Validation of the method has been carried out using a transonic annular turbine nozzle and NASA rotor 67. Finally, the method is demonstrated on the re-design of the blades.

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