scholarly journals An Image Recognition-Based Approach to Actin Cytoskeleton Quantification

Electronics ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 443 ◽  
Author(s):  
Yi Liu ◽  
Keyvan Mollaeian ◽  
Juan Ren
Keyword(s):  
Actin Cytoskeleton ◽  
Image Recognition ◽  
Average Error ◽  
Latrunculin B ◽  
Cytoskeletal Organization ◽  
Detection Algorithms ◽  
Edge Detectors ◽  
Mesh Work ◽  
Quantification Accuracy ◽  
Nih 3T3

Quantification of the actin cytoskeleton is of prime importance to unveil the cellular force sensing and transduction mechanism. Although fluorescence imaging provides a convenient tool for observing the morphology of the actin cytoskeleton, due to the lack of approaches to accurate actin cytoskeleton quantification, the dynamics of mechanotransduction is still poorly understood. Currently, the existing image-based actin cytoskeleton analysis tools are either incapable of quantifying both the orientation and the quantity of the actin cytoskeleton simultaneously or the quantified results are subject to analysis artifacts. In this study, we propose an image recognition-based actin cytoskeleton quantification (IRAQ) approach, which quantifies both the actin cytoskeleton orientation and quantity by using edge, line, and brightness detection algorithms. The actin cytoskeleton is quantified through three parameters: the partial actin-cytoskeletal deviation (PAD), the total actin-cytoskeletal deviation (TAD), and the average actin-cytoskeletal intensity (AAI). First, Canny and Sobel edge detectors are applied to skeletonize the actin cytoskeleton images, then PAD and TAD are quantified using the line directions detected by Hough transform, and AAI is calculated through the summational brightness over the detected cell area. To verify the quantification accuracy, the proposed IRAQ was applied to six artificially-generated actin cytoskeleton mesh work models. The average error for both the quantified PAD and TAD was less than 1.22 ∘ . Then, IRAQ was implemented to quantify the actin cytoskeleton of NIH/3T3 cells treated with an F-actin inhibitor (latrunculin B). The quantification results suggest that the local and total actin-cytoskeletal organization became more disordered with the increase of latrunculin B dosage, and the quantity of the actin cytoskeleton showed a monotonically decreasing relation with latrunculin B dosage.

Modeling and Control of Dynamic Cellular Mechanotransduction: Part I — Actin Cytoskeleton Quantification

2018 ◽  
Author(s):  
Yi Liu ◽  
Juan Ren
Keyword(s):  
Actin Cytoskeleton ◽  
Average Error ◽  
Cytoskeletal Organization ◽  
Modeling And Control ◽  
Cellular Mechanotransduction ◽  
Edge Detectors ◽  
Quantification Accuracy ◽  
And Control ◽  
Nih 3T3 ◽  
External Stimuli

Living cells respond to external stimuli through the reorganization of the actin cytoskeleton, and the actin cytoskeleton significantly affects the cellular mechanical behavior. However, due to the lack of approaches to actin cytoskeleton quantification, the dynamics of mechanotransduction is still poorly understood. In this study, we propose an image recognition-based quantification (IRQ) approach to actin cytoskeleton quantification. IRQ quantifies the actin cytoskeleton through three parameters: the partial actin-cytoskeletal deviation (PAD), the total actin-cytoskeletal deviation (TAD) and the average actin-cytoskeletal intensity (AAI). First, Canny and Sobel edge detectors are applied to skeletonize the actin cytoskeleton images, then PAD and TAD are quantified using the direction of lines detected by Hough transform, and AAI is calculated through the summational brightness over the detected cell area. For validation, six different actin cytoskeleton meshwork models were generated to verify the quantification accuracy of IRQ. The average error for both the quantified PAD and TAD was less than 1.22°. Then IRQ was implemented to quantify the actin cytoskeleton of NIH/3T3 cells treated with an F-actin inhibitor. The quantification results suggest that the local and total actin-cytoskeletal organization of treated cells were more disordered than untreated cells, and the quantity of the actin cytoskeleton decreased significantly after the F-actin treatment.

scholarly journals Research on Robustness of Related Images for Power Equipment Inspection

2021 ◽  
Vol 2113 (1) ◽  
pp. 012045
Author(s):  
Chunlei Zhou ◽  
Xiangzhou Chen ◽  
Wenli Liu ◽  
Tianyu Dong ◽  
Huang Yun
Keyword(s):  
Deep Learning ◽  
Image Recognition ◽  
Feature Fusion ◽  
Power Equipment ◽  
Actual Measurement ◽  
Practical Applications ◽  
Detection Algorithms ◽  
Traction Substations ◽  
Deep Learning Model ◽  
Selection Of

Abstract With the increase in the number of traction substations year by year, manual inspections are gradually being replaced by unattended inspections. Target detection algorithms based on deep learning are more widely used in intelligent inspections of power equipment. However, in practical applications, it is found that due to the small target to be detected, the accuracy of the deep learning model will decrease when the shooting angle is inclined and the light conditions are poor. This is because the algorithm’s robustness is low, and the detection ability of the model will be seriously affected when the angle or illumination difference with the sample is large. Based on this, the feature fusion part of the YOLOv3 algorithm and the selection of the loss function and the size of the anchor frame are improved, and the improved ASFF fusion method is used to classify various images in the power equipment. Actual measurement and repeated experiments show that the proposed method can be effectively applied to image recognition of various power equipment, optimize robustness, and greatly improve the image recognition efficiency of power equipment.

Effects of latrunculin B on the actin cytoskeleton and hyphal growth in Phytophthora infestans

2012 ◽  
Vol 49 (12) ◽  
pp. 1014-1022 ◽  
Author(s):  
Tijs Ketelaar ◽  
Harold J.G. Meijer ◽  
Marjolein Spiekerman ◽  
Rob Weide ◽  
Francine Govers
Keyword(s):  
Actin Cytoskeleton ◽  
Phytophthora Infestans ◽  
Hyphal Growth ◽  
Latrunculin B

scholarly journals System-wide organization of actin cytoskeleton determines organelle transport in hypocotyl plant cells

2017 ◽  
Vol 114 (28) ◽  
pp. E5741-E5749 ◽  
Author(s):  
David Breuer ◽  
Jacqueline Nowak ◽  
Alexander Ivakov ◽  
Marc Somssich ◽  
Staffan Persson ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Plant Cells ◽  
System Level ◽  
Organelle Transport ◽  
Cellular Transport ◽  
Actin Network ◽  
Cytoskeletal Organization ◽  
Quantitative Evidence ◽  
Golgi Transport ◽  
Distribution Efficiency

The actin cytoskeleton is an essential intracellular filamentous structure that underpins cellular transport and cytoplasmic streaming in plant cells. However, the system-level properties of actin-based cellular trafficking remain tenuous, largely due to the inability to quantify key features of the actin cytoskeleton. Here, we developed an automated image-based, network-driven framework to accurately segment and quantify actin cytoskeletal structures and Golgi transport. We show that the actin cytoskeleton in both growing and elongated hypocotyl cells has structural properties facilitating efficient transport. Our findings suggest that the erratic movement of Golgi is a stable cellular phenomenon that might optimize distribution efficiency of cell material. Moreover, we demonstrate that Golgi transport in hypocotyl cells can be accurately predicted from the actin network topology alone. Thus, our framework provides quantitative evidence for system-wide coordination of cellular transport in plant cells and can be readily applied to investigate cytoskeletal organization and transport in other organisms.

scholarly journals Macropinocytosis Is the Entry Mechanism of Amphotropic Murine Leukemia Virus

2014 ◽  
Vol 89 (3) ◽  
pp. 1851-1866 ◽  
Author(s):  
Izabela Rasmussen ◽  
Frederik Vilhardt
Keyword(s):  
Cell Surface ◽  
Actin Cytoskeleton ◽  
Murine Leukemia Virus ◽  
Mammalian Cells ◽  
Leukemia Virus ◽  
Amphotropic Murine Leukemia Virus ◽  
Conditional Expression ◽  
Nih 3T3 ◽  
Entry Mechanism ◽  
Murine Leukemia

ABSTRACTThe entry mechanism of murine amphotropic retrovirus (A-MLV) has not been unambiguously determined. We show here that A-MLV is internalized not by caveolae or other pinocytic mechanisms but by macropinocytosis. Thus, A-MLV infection of mouse embryonic fibroblasts deficient for caveolin or dynamin, and NIH 3T3 cells knocked down for caveolin expression, was unaffected. Conversely, A-MLV infection of NIH 3T3 and HeLa cells was sensitive to amiloride analogues and actin-depolymerizing drugs that interfere with macropinocytosis. Further manipulation of the actin cytoskeleton through conditional expression of dominant positive or negative mutants of Rac1, PAK1, and RhoG, to increase or decrease macropinocytosis, similarly correlated with an augmented or inhibited infection with A-MLV, respectively. The same experimental perturbations affected the infection of viruses that use clathrin-coated-pit endocytosis or other pathways for entry only mildly or not at all. These data agree with immunofluorescence studies and cryo-immunogold labeling for electron microscopy, which demonstrate the presence of A-MLV in protrusion-rich areas of the cell surface and in cortical fluid phase (dextran)-filled macropinosomes, which also account for up to a half of the cellular uptake of the cell surface-binding lectin concanavalin A. We conclude that A-MLV use macropinocytosis as the predominant entry portal into cells.IMPORTANCEBinding and entry of virus particles into mammalian cells are the first steps of infection. Understanding how pathogens and toxins exploit or divert endocytosis pathways has advanced our understanding of membrane trafficking pathways, which benefits development of new therapeutic schemes and methods of drug delivery. We show here that amphotropic murine leukemia virus (A-MLV) pseudotyped with the amphotropic envelope protein (which expands the host range to many mammalian cells) gains entry into host cells by macropinocytosis. Macropinosomes form as large, fluid-filled vacuoles (up to 10 μm) following the collapse of cell surface protrusions and membrane scission. We used drugs or the introduction of mutant proteins that affect the actin cytoskeleton and cell surface dynamics to show that macropinocytosis and A-MLV infection are correlated, and we provide both light- and electron-microscopic evidence to show the localization of A-MLV in macropinosomes. Finally, we specifically exclude some other potential entry portals, including caveolae, previously suggested to internalize A-MLV.

Plexin-A4 promotes tumor progression and tumor angiogenesis by enhancement of VEGF and bFGF signaling

Blood ◽  
2011 ◽  
Vol 118 (15) ◽  
pp. 4285-4296 ◽  
Author(s):  
Boaz Kigel ◽  
Noa Rabinowicz ◽  
Asya Varshavsky ◽  
Ofra Kessler ◽  
Gera Neufeld
Keyword(s):  
Cell Proliferation ◽  
Endothelial Cells ◽  
Tyrosine Kinase ◽  
Actin Cytoskeleton ◽  
Tumor Progression ◽  
Tumor Angiogenesis ◽  
Tumor Formation ◽  
Tyrosine Kinase Receptors ◽  
Glioblastoma Cells ◽  
Cytoskeletal Organization

Abstract Plexin-A4 is a receptor for sema6A and sema6B and associates with neuropilins to transduce signals of class-3 semaphorins. We observed that plexin-A1 and plexin-A4 are required simultaneously for transduction of inhibitory sema3A signals and that they form complexes. Unexpectedly, inhibition of plexin-A1 or plexin-A4 expression in endothelial cells using specific shRNAs resulted in prominent plexin type specific rearrangements of the actin cytoskeleton that were accompanied by inhibition of bFGF and VEGF-induced cell proliferation. The two responses were not interdependent since silencing plexin-A4 in U87MG glioblastoma cells inhibited cell proliferation and strongly inhibited the formation of tumors from these cells without affecting cytoskeletal organization. Plexin-A4 formed stable complexes with the FGFR1 and VEGFR-2 tyrosine-kinase receptors and enhanced VEGF-induced VEGFR-2 phosphorylation in endothelial cells as well as bFGF-induced cell proliferation. We also obtained evidence suggesting that some of the pro-proliferative effects of plexin-A4 are due to transduction of autocrine sema6B-induced pro-proliferative signals, since silencing sema6B expression in endothelial cells and in U87MG cells mimicked the effects of plexin-A4 silencing and also inhibited tumor formation from the U87MG cells. Our results suggest that plexin-A4 may represent a target for the development of novel anti-angiogenic and anti-tumorigenic drugs.

scholarly journals The Edge Detectors Suitable for Retinal OCT Image Segmentation

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Su Luo ◽  
Jing Yang ◽  
Qian Gao ◽  
Sheng Zhou ◽  
Chang’an A. Zhan
Keyword(s):  
Image Segmentation ◽  
Edge Detection ◽  
Thickness Measurement ◽  
Retinal Layer ◽  
Detection Algorithms ◽  
Edge Detectors ◽  
Canny Edge ◽  
Segmentation Task ◽  
Effective Use ◽  
Oct Image

Retinal layer thickness measurement offers important information for reliable diagnosis of retinal diseases and for the evaluation of disease development and medical treatment responses. This task critically depends on the accurate edge detection of the retinal layers in OCT images. Here, we intended to search for the most suitable edge detectors for the retinal OCT image segmentation task. The three most promising edge detection algorithms were identified in the related literature: Canny edge detector, the two-pass method, and the EdgeFlow technique. The quantitative evaluation results show that the two-pass method outperforms consistently the Canny detector and the EdgeFlow technique in delineating the retinal layer boundaries in the OCT images. In addition, the mean localization deviation metrics show that the two-pass method caused the smallest edge shifting problem. These findings suggest that the two-pass method is the best among the three algorithms for detecting retinal layer boundaries. The overall better performance of Canny and two-pass methods over EdgeFlow technique implies that the OCT images contain more intensity gradient information than texture changes along the retinal layer boundaries. The results will guide our future efforts in the quantitative analysis of retinal OCT images for the effective use of OCT technologies in the field of ophthalmology.

scholarly journals Clostridium difficile Toxins A and B Directly Stimulate Human Mast Cells

2007 ◽  
Vol 75 (8) ◽  
pp. 3868-3876 ◽  
Author(s):  
Gesa K. A. Meyer ◽  
Anne Neetz ◽  
Gudrun Brandes ◽  
Dimitrios Tsikas ◽  
Joseph H. Butterfield ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Clostridium Difficile ◽  
Actin Cytoskeleton ◽  
Cell Line ◽  
P38 Mapk ◽  
Rho Gtpases ◽  
Human Mast Cell ◽  
Direct Effects ◽  
Latrunculin B

ABSTRACT Clostridium difficile toxins A and B (TcdA and TcdB) are the causative agents of antibiotic-associated pseudomembranous colitis. Mucosal mast cells play a crucial role in the inflammatory processes underlying this disease. We studied the direct effects of TcdA and TcdB on the human mast cell line HMC-1 with respect to degranulation, cytokine release, and the activation of proinflammatory signal pathways. TcdA and TcdB inactivate Rho GTPases, the master regulators of the actin cytoskeleton. The inactivation of Rho GTPases induced a reorganization of the actin cytoskeleton accompanied by morphological changes of cells. The TcdB-induced reorganization of the actin cytoskeleton in HMC-1 cells reduced the number of electron-dense mast cell-specific granules. Accordingly, TcdB induced the release of hexosaminidase, a marker for degranulation, in HMC-1 cells. The actin rearrangement was found to be responsible for degranulation since latrunculin B induced a comparable hexosaminidase release. In addition, TcdB as well as latrunculin B induced the activation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase 1/2 and also resulted in a p38 MAPK-dependent increased formation of prostaglandins D2 and E2. The autocrine stimulation of HMC-1 cells by prostaglandins partially contributed to the degranulation. Interestingly, TcdB-treated HMC-1 cells, but not latrunculin B-treated HMC-1 cells, showed a strong p38 MAPK-dependent increase in interleukin-8 release. Differences in the mast cell responses to TcdB and latrunculin B are probably due to the presence of functionally inactive Rho GTPases in toxin-treated cells. Thus, the HMC-1 cell line is a promising model for studying the direct effects of C. difficile toxins on mast cells independently of the tissue context.

The actin cytoskeleton facilitates complement-mediated activation of cytosolic phospholipase A2

2004 ◽  
Vol 286 (3) ◽  
pp. F466-F476 ◽  
Author(s):  
Andrey V. Cybulsky ◽  
Tomoko Takano ◽  
Joan Papillon ◽  
Abdelkrim Khadir ◽  
Krikor Bijian ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Tyrosine Kinases ◽  
Actin Filaments ◽  
Cytochalasin D ◽  
Cell Periphery ◽  
Calyculin A ◽  
Latrunculin B ◽  
Glomerular Epithelial Cell ◽  
Cytosolic Phospholipase ◽  
Microsomal Membranes

Cytosolic PLA2-α (cPLA2) and metabolites of arachidonic acid (AA) are key mediators of complement-dependent glomerular epithelial cell (GEC) injury. Assembly of C5b-9 increases cytosolic Ca2+ concentration and results in transactivation of receptor tyrosine kinases and activation of PLC-γ1 and the 1,2-diacylglycerol (DAG)-PKC pathway. Ca2+ and PKC are essential for membrane association and increased catalytic activity of cPLA2. This study addresses the role of the actin cytoskeleton in cPLA2 activation. Depolymerization of F-actin by cytochalasin D or latrunculin B reduced complement-dependent [3H]AA release, as well as the complement-induced increase in cPLA2 activity. These effects were due to inhibition of [3H]DAG production and PKC activation, implying interference with PLC. Complement-dependent [3H]AA release was also reduced by jasplakinolide, a compound that stabilizes F-actin and organizes actin filaments at the cell periphery, and calyculin A, which induces condensation of actin filaments at the plasma membrane. The latter drugs did not affect [3H]DAG production, suggesting their inhibitory actions were downstream of PKC. Neither cytochalasin D, latrunculin B, nor calyculin A affected association of cPLA2 with microsomal membranes, and cytochalasin D and latrunculin B did not alter the localization of the endoplasmic reticulum. Stable transfection of constitutively active RhoA induced formation of stress fibers, stabilized F-actin, and attenuated the complement-induced increase in [3H]AA. Thus in GEC, cPLA2 activation is dependent, in part, on actin remodeling. By regulating complement-mediated activation of cPLA2, the actin cytoskeleton may contribute to the pathophysiology of GEC injury.

scholarly journals Effect of F-actin and Microtubules on Cellular Mechanical Behavior Studied Using Atomic Force Microscope and an Image Recognition-Based Cytoskeleton Quantification Approach

2020 ◽  
Vol 21 (2) ◽  
pp. 392 ◽  
Author(s):  
Yi Liu ◽  
Keyvan Mollaeian ◽  
Muhammad Huzaifah Shamim ◽  
Juan Ren
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Atomic Force Microscope ◽  
Image Recognition ◽  
3T3 Cells ◽  
Atomic Force ◽  
Cellular Cytoskeleton ◽  
Nih 3T3 ◽  
And Diffusion ◽  
Nih 3T3 Cells

Cytoskeleton morphology plays a key role in regulating cell mechanics. Particularly, cellular mechanical properties are directly regulated by the highly cross-linked and dynamic cytoskeletal structure of F-actin and microtubules presented in the cytoplasm. Although great efforts have been devoted to investigating the qualitative relation between the cellular cytoskeleton state and cell mechanical properties, comprehensive quantification results of how the states of F-actin and microtubules affect mechanical behavior are still lacking. In this study, the effect of both F-actin and microtubules morphology on cellular mechanical properties was quantified using atomic force microscope indentation experiments together with the proposed image recognition-based cytoskeleton quantification approach. Young’s modulus and diffusion coefficient of NIH/3T3 cells with different cytoskeleton states were quantified at different length scales. It was found that the living NIH/3T3 cells sense and adapt to the F-actin and microtubules states: both the cellular elasticity and poroelasticity are closely correlated to the depolymerization degree of F-actin and microtubules at all measured indentation depths. Moreover, the significance of the quantitative effects of F-actin and microtubules in affecting cellular mechanical behavior is depth-dependent.

Sign in / Sign up

Export Citation Format

Share Document