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- Hernandez-Hernandez, A, et al.
(författare)
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The central element of the synaptonemal complex in mice is organized as a bilayered junction structure
- 2016
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Ingår i: Journal of cell science. - : The Company of Biologists. - 1477-9137 .- 0021-9533. ; 129:11, s. 2239-2249
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Tidskriftsartikel (refereegranskat)abstract
- The synaptonemal complex (SC) transiently stabilizes pairing interactions between homologous chromosomes during meiosis. Assembly of the SC is mediated through integration of opposing transverse filaments (TF) into a central element (CE), a process that is poorly understood. We have here analyzed the localization of the TF protein SYCP1 and the CE proteins SYCE1, SYCE2 and SYCE3 within the central region of the SC in mouse spermatocytes using immunoelectron microscopy. Distribution of immuno-gold particles in a lateral view of the SC, supported by protein interaction data, suggest that the N-terminal region of SYCP1 and SYCE3 form a joint bilayered central structure and that SYCE1 and SYCE2 localize in between the two layers. We find that disruption of SYCE2 and TEX12 (a fourth CE protein) localization to the CE abolishes central alignment of the N-terminal region of SYCP1. Thus, our results show that all four CE proteins in an interdependent manner contribute to stabilization of opposing N-terminal regions of SYCP1, forming a bilayered TF-CE junction structure that promotes SC formation and synapsis.
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| 9. |
- Narangifard, A., et al.
(författare)
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Human skin barrier formation takes place via a cubic to lamellar lipid phase transition as analyzed by cryo-electron microscopy and EM-simulation
- 2018
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 366:2, s. 139-151
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Tidskriftsartikel (refereegranskat)abstract
- The skin's permeability barrier consists of stacked lipid sheets of splayed ceramides, cholesterol and free fatty acids, positioned intercellularly in the stratum corneum. We report here on the early stage of skin barrier formation taking place inside the tubuloreticular system in the secretory cells of the topmost viable epidermis and in the intercellular space between viable epidermis and stratum corneum. The barrier formation process was analysed in situ in its near-native state, using cryo-EM combined with molecular dynamics modeling and EM simulation. Stacks of lamellae appear towards the periphery of the tubuloreticular system and they are closely associated with granular regions. Only models based on a bicontinuous cubic phase organization proved compatible with the granular cryo-EM patterns. Only models based on a dehydrated lamellar phase organization agreed with the lamellar cryo-EM patterns. The data support that human skin barrier formation takes place via a cubic to lamellar lipid phase transition.
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- Rullgard, H., et al.
(författare)
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Simulation of transmission electron microscope images of biological specimens
- 2011
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Ingår i: Journal of Microscopy. - : Wiley. - 0022-2720 .- 1365-2818. ; 243:3, s. 234-256
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Tidskriftsartikel (refereegranskat)abstract
- We present a new approach to simulate electron cryo-microscope images of biological specimens. The framework for simulation consists of two parts; the first is a phantom generator that generates a model of a specimen suitable for simulation, the second is a transmission electron microscope simulator. The phantom generator calculates the scattering potential of an atomic structure in aqueous buffer and allows the user to define the distribution of molecules in the simulated image. The simulator includes a well defined electron-specimen interaction model based on the scalar Schrodinger equation, the contrast transfer function for optics, and a noise model that includes shot noise as well as detector noise including detector blurring. To enable optimal performance, the simulation framework also includes a calibration protocol for setting simulation parameters. To test the accuracy of the new framework for simulation, we compare simulated images to experimental images recorded of the Tobacco Mosaic Virus (TMV) in vitreous ice. The simulated and experimental images show good agreement with respect to contrast variations depending on dose and defocus. Furthermore, random fluctuations present in experimental and simulated images exhibit similar statistical properties. The simulator has been designed to provide a platform for development of new instrumentation and image processing procedures in single particle electron microscopy, two-dimensional crystallography and electron tomography with well documented protocols and an open source code into which new improvements and extensions are easily incorporated.
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| 14. |
- Shahidi, MK, et al.
(författare)
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Three-dimensional Imaging Reveals New Compartments and Structural Adaptations in Odontoblasts
- 2015
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Ingår i: Journal of dental research. - : SAGE Publications. - 1544-0591 .- 0022-0345. ; 94:7, s. 945-954
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Tidskriftsartikel (refereegranskat)abstract
- In organized tissues, the precise geometry and the overall shape are critical for the specialized functions that the cells carry out. Odontoblasts are major matrix-producing cells of the tooth and have also been suggested to participate in sensory transmission. However, refined morphologic data on these important cells are limited, which hampers the analysis and understanding of their cellular functions. We took advantage of fluorescent color-coding genetic tracing to visualize and reconstruct in 3 dimensions single odontoblasts, pulp cells, and their assemblages. Our results show distinct structural features and compartments of odontoblasts at different stages of maturation, with regard to overall cellular shape, formation of the main process, orientation, and matrix deposition. We demonstrate previously unanticipated contacts between the processes of pulp cells and odontoblasts. All reported data are related to mouse incisor tooth. We also show that odontoblasts express TRPM5 and Piezo2 ion channels. Piezo2 is expressed ubiquitously, while TRPM5 is asymmetrically distributed with distinct localization to regions proximal to and within odontoblast processes.
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