scholarly journals Inferring cell junction tension and pressure from cell geometry

Development ◽  
2021 ◽  
Vol 148 (18) ◽  
pp. dev192773
Author(s):  
Chloé Roffay ◽  
Chii J. Chan ◽  
Boris Guirao ◽  
Takashi Hiiragi ◽  
François Graner
Keyword(s):  
Three Dimensional ◽  
Cell Junction ◽  
Cell Geometry ◽  
Early Mouse Embryo ◽  
Validity Criteria ◽  
Early Mouse ◽  
Computational Analyses ◽  
Non Destructive

ABSTRACTRecognizing the crucial role of mechanical regulation and forces in tissue development and homeostasis has stirred a demand for in situ measurement of forces and stresses. Among emerging techniques, the use of cell geometry to infer cell junction tensions, cell pressures and tissue stress has gained popularity owing to the development of computational analyses. This approach is non-destructive and fast, and statistically validated based on comparisons with other techniques. However, its qualitative and quantitative limitations, in theory as well as in practice, should be examined with care. In this Primer, we summarize the underlying principles and assumptions behind stress inference, discuss its validity criteria and provide guidance to help beginners make the appropriate choice of its variants. We extend our discussion from two-dimensional stress inference to three dimensional, using the early mouse embryo as an example, and list a few possible extensions. We hope to make stress inference more accessible to the scientific community and trigger a broader interest in using this technique to study mechanics in development.

scholarly journals Transport and localization of exogenous myelin basic protein mRNA microinjected into oligodendrocytes.

1993 ◽  
Vol 123 (2) ◽  
pp. 431-441 ◽  
Author(s):  
K Ainger ◽  
D Avossa ◽  
F Morgan ◽  
S J Hill ◽  
C Barry ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Living Cells ◽  
Branch Points ◽  
Rna Granules ◽  
Intracellular Movement ◽  
Directional Movement ◽  
Ionic Detergent ◽  
Mrna Granules

We have studied transport and localization of MBP mRNA in oligodendrocytes in culture by microinjecting labeled mRNA into living cells and analyzing the intracellular distribution of the injected RNA by confocal microscopy. Injected mRNA initially appears dispersed in the perikaryon. Within minutes, the RNA forms granules which, in the case of MBP mRNA, are transported down the processes to the periphery of the cell where the distribution again becomes dispersed. In situ hybridization shows that endogenous MBP mRNA in oligodendrocytes also appears as granules in the perikaryon and processes and dispersed in the peripheral membranes. The granules are not released by extraction with non-ionic detergent, indicating that they are associated with the cytoskeletal matrix. Three dimensional visualization indicates that MBP mRNA granules are often aligned in tracks along microtubules traversing the cytoplasm and processes. Several distinct patterns of granule movement are observed. Granules in the processes undergo sustained directional movement with a velocity of approximately 0.2 micron/s. Granules at branch points undergo oscillatory motion with a mean displacement of 0.1 micron/s. Granules in the periphery of the cell circulate randomly with a mean displacement of approximately 1 micron/s. The results are discussed in terms of a multi-step pathway for transport and localization of MBP mRNA in oligodendrocytes. This work represents the first characterization of intracellular movement of mRNA in living cells, and the first description of the role of RNA granules in transport and localization of mRNA in cells.

Diversity of the sponge fauna associated with white coral banks from two Sardinian canyons (Mediterranean Sea)

2019 ◽  
Vol 99 (8) ◽  
pp. 1735-1751 ◽  
Author(s):  
M. Bertolino ◽  
S. Ricci ◽  
S. Canese ◽  
A. Cau ◽  
G. Bavestrello ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Cold Water ◽  
Three Dimensional ◽  
Western Mediterranean ◽  
Tyrrhenian Sea ◽  
Lophelia Pertusa ◽  
Wide Range ◽  
Santa Maria

AbstractThe three-dimensional coral scaffolds formed by the skeletons of the cold-water corals Madrepora oculata and Lophelia pertusa represent an important deep-sea hard substratum and create an optimal shelter for a rich associated fauna in which the contribution of Porifera has still not been fully considered. The taxonomic analysis of sponges collected from two Sardinian canyons (Nora and Coda Cavallo, 256–408 m) and associated with the dead coral matrix resulted in 28 species, including new records for the Mediterranean Sea, Italian fauna or Central Tyrrhenian Sea. In addition, for many species this is the first finding associated with the coral framework or the first documentation of the in situ morphology. The taxonomic comparison with sponge assemblages associated with coral frameworks from Santa Maria di Leuca, Strait of Sicily and Bari Canyon, gave the opportunity to evaluate the similarities among geographically separated banks. Overall, the percentage of exclusive species (recorded only in one site), is very high (81%) and only one species is shared by all four sites, suggesting a low connectivity among the sponge communities. The percentage of shared species is higher for the Maltese community, supporting the role of the Sicily Channel as a crossroads between the communities of the eastern and western Mediterranean basins. Here, 55% of the sponges associated to the coral framework are also reported in shallow-water coralligenous assemblages, indicating a high bathymetric connectivity as well as an ecological plasticity allowing these species to occupy a wide range of small, dark refuges.

The chicken stathmin gene and its expression in the embryo

2000 ◽  
Vol 78 (6) ◽  
pp. 703-713 ◽  
Author(s):  
Sharon Soodeen-Karamath ◽  
Ann M Verrinder Gibbins
Keyword(s):  
Es Cells ◽  
Embryonic Stem ◽  
Early Mouse Embryo ◽  
Differentiated Cells ◽  
Selective Ablation ◽  
Potential Indicator ◽  
Early Mouse ◽  
Intron 2

Stathmin, which functions as an intracellular relay in signal transduction pathways, has been suggested as a potential indicator of pluripotent cells in the early mouse embryo. In this study, chicken stathmin cDNA and genomic DNA were analyzed. In mammals stathmin consists of five exons and four introns; exons 3, 4, and 5 in the mammalian stathmin gene are equivalent to one relatively large exon in the chicken stathmin gene. Introns equivalent to introns 3 and 4 in the mammalian stathmin gene are not present in the counterpart gene in chickens and, although intron 2 was shown to be present in both mammals and birds, it is smaller in the chicken stathmin gene. Despite differences in the genomic organization of the gene and its smaller size in chickens compared with that in humans and mice, similarities in the coding sequences and in the expression of the chicken and mouse stathmin genes at certain stages of embryo development, as determined by whole-mount in situ hybridization experiments, suggest that their products are functional homologues. The argument is thus substantiated for further investigations into the use of regulatory regions of the stathmin gene in a system for the establishment of long-term cultures of germline competent chicken embryonic stem (ES) cells by the selective ablation of differentiated cells in culture using drug selection.Key words: stathmin, chicken, ES cells, oct 3/4.

The role of the nucleocytoplasmic ratio in development regulation of the early mouse embryo

Development ◽  
1990 ◽  
Vol 109 (2) ◽  
pp. 323-328 ◽  
Author(s):  
S.V. Evsikov ◽  
L.M. Morozova ◽  
A.P. Solomko
Keyword(s):  
Biological Clock ◽  
Mouse Embryos ◽  
Early Mouse Embryo ◽  
Cell Divisions ◽  
Preimplantation Mouse Embryos ◽  
Preimplantation Mouse ◽  
Early Mouse ◽  
Development Regulation ◽  
Clock Mechanism

The hypothesis suggesting that the blastocoele is able to form only at a definite nucleocytoplasmic ratio was tested. We compared the development of preimplantation mouse embryos under different conditions. The results demonstrated that the start of cavitation is not dependent on the number of cell divisions. Thus, a definite nucleocytoplasmic ratio is not required for blastocoele formation to start. Our studies on embryos with microsurgically altered cytoplasm content provided evidence for the following biological clock mechanism: a change in the cell program of morphogenesis needs definite concentration of the products of a previous genetic program.

A Model of Stress and Strain in the Interosseous Ligament of the Forearm Based on Fiber Network Theory

2006 ◽  
Vol 128 (5) ◽  
pp. 725-732 ◽  
Author(s):  
H. James Pfaeffle ◽  
Kenneth J. Fischer ◽  
Arun Srinivasa ◽  
Theodore Manson ◽  
Savio L-Y. Woo ◽  
...  
Keyword(s):  
Network Model ◽  
Network Theory ◽  
Three Dimensional ◽  
Experimental Result ◽  
Stress And Strain ◽  
Forearm Rotation ◽  
Fiber Network ◽  
Interosseous Ligament

Fiber network theory was developed to describe cloth, a thin material with strength in the fiber directions. The interosseous ligament (IOL) of the forearm is a broad, thin ligament with highly aligned fibers. The objectives of this study were to develop a model of the stress and strain distributions in the IOL, based on fiber network theory, to compare the strains from the model with the experimentally measured strains, and to evaluate the force distribution across the ligament fibers from the model. The geometries of the radius, ulna, and IOL were reconstructed from CT scans. Position and orientation of IOL insertion sites and force in the IOL were measured during a forearm compression experiment in pronation, neutral rotation, and supination. An optical image-based technique was used to directly measure strain in two regions of the IOL in neutral rotation. For the network model, the IOL was represented as a parametric ruled three-dimensional surface, with rulings along local fiber directions. Fiber strains were calculated from the deformation field, and fiber stresses were calculated from the strains using average IOL tensile properties from a previous study. The in situ strain in the IOL was assumed uniform and was calculated so that the net force predicted by the network model in neutral rotation matched the experimental result. The net force in the IOL was comparable to experimental results in supination and pronation. The model predicted higher stress and strain in fibers near the elbow in neutral rotation, and higher stresses in fibers near the wrist in supination. Strains in neutral forearm rotation followed the same trends as those measured experimentally. In this study, a model of stress and strain in the IOL utilizing fiber network theory was successfully implemented. The model illustrates variations in the stress and strain distribution in the IOL. This model can be used to show surgeons how different fibers are taut in different forearm rotation positions—this information is important for understanding the biomechanical role of the IOL and for planning an IOL reconstruction.

Three-dimensional Gd-doped TiO2 fibrous photoelectrodes for efficient visible light-driven photocatalytic performance

RSC Advances ◽  
2014 ◽  
Vol 4 (23) ◽  
pp. 11750-11757 ◽  
Author(s):  
Junghyun Choi ◽  
P. Sudhagar ◽  
P. Lakshmipathiraj ◽  
Jung Woo Lee ◽  
Anitha Devadoss ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Photocatalytic Performance ◽  
Three Dimensional ◽  
Electrode Geometry ◽  
Doped Tio2 ◽  
Visible Light Driven

Demonstration of the role of electrode geometry on in situ Gd-doping and their effects in the photocatalytic activity.

Localization of Partial Magnetization around Artificial Slits in Square Bars of Medium Carbon Low Alloy Steel JIS S45C

2011 ◽  
Vol 217-218 ◽  
pp. 1297-1302 ◽  
Author(s):  
M. Uryu ◽  
Katsuyuki Kida ◽  
Takashi Honda ◽  
Edson Costa Santos ◽  
K. Saruwatari
Keyword(s):  
Stress Concentration ◽  
Three Dimensional ◽  
Hall Probe ◽  
Low Alloy Steels ◽  
Film Sensor ◽  
Medium Carbon ◽  
Alloy Steels ◽  
Probe Microscope ◽  
Non Destructive

Fatigue failure of steel occurs when cracks form and grow in the material’s stress concentration area. In order to understand the relation between stress concentration and crack propagation phenomena, non-destructive evaluation methods that can be related to in-situ measurements around the stress concentration area are necessary. In the present work, we developed a scanning Hall probe microscope (SHPM) equipped in a GaAs film sensor and observed three dimensional magnetic fields at room temperature in air. Medium carbon low alloy steels specimens (JIS, S45C) were used in the experiments. Only the area around the artificial slit had been magnetized and the effect of the magnetization area on the artificial slit was observed.

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