scholarly journals Dynamic changes in the association between maternal mRNAs and endoplasmic reticulum during ascidian early embryogenesis

2021 ◽  
Author(s):  
Toshiyuki Goto ◽  
Shuhei Torii ◽  
Aoi Kondo ◽  
Junji Kawakami ◽  
Haruka Yagi ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Translational Regulation ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Early Embryogenesis ◽  
Axis Formation ◽  
Second Phase ◽  
Dynamic Changes ◽  
Maternal Mrna ◽  
Maternal Mrnas

AbstractAxis formation is one of the most important events occurring at the beginning of animal development. In the ascidian egg, the antero-posterior axis is established at this time owing to a dynamic cytoplasmic movement called cytoplasmic and cortical reorganisation. During this movement, mitochondria, endoplasmic reticulum (ER), and maternal mRNAs (postplasmic/PEM RNAs) are translocated to the future posterior side. Although accumulating evidence indicates the crucial roles played by the asymmetrical localisation of these organelles and the translational regulation of postplasmic/PEM RNAs, the organisation of ER has not been described in sufficient detail to date owing to technical difficulties. In this study, we developed three different multiple staining protocols for visualising the ER in combination with mitochondria, microtubules, or mRNAs in whole-mount specimens. We defined the internally expanded “dense ER” using these protocols and described cisterna-like structures of the dense ER using focused ion beam-scanning electron microscopy. Most importantly, we described the dynamic changes in the colocalisation of postplasmic/PEM mRNAs and dense ER; for example, macho-1 mRNA was detached and excluded from the dense ER during the second phase of ooplasmic movements. These detailed descriptions of the association between maternal mRNA and ER can provide clues for understanding the translational regulation mechanisms underlying axis determination during ascidian early embryogenesis.

scholarly journals The GNU subunit of PNG kinase, the developmental regulator of mRNA translation, binds BIC-C to localize to RNP granules

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Emir E Avilés-Pagán ◽  
Masatoshi Hara ◽  
Terry L Orr-Weaver
Keyword(s):  
Translational Regulation ◽  
Mrna Translation ◽  
Mature Oocyte ◽  
Early Embryogenesis ◽  
Egg Activation ◽  
Maternal Mrna ◽  
Rnp Granules

Control of mRNA translation is a key mechanism by which the differentiated oocyte transitions to a totipotent embryo. In Drosophila, the PNG kinase complex regulates maternal mRNA translation at the oocyte-to-embryo transition. We previously showed the GNU activating subunit is crucial in regulating PNG and timing its activity to the window between egg activation and early embryogenesis (Hara et al., 2017). In this study, we find associations between GNU and proteins of RNP granules and demonstrate that GNU localizes to cytoplasmic RNP granules in the mature oocyte, identifying GNU as a new component of a subset of RNP granules. Furthermore, we define roles for the domains of GNU. Interactions between GNU and the granule component BIC-C reveal potential conserved functions for translational regulation in metazoan development. We propose that by binding to BIC-C, upon egg activation GNU brings PNG to its initial targets, translational repressors in RNP granules.

Characterization of Second-Phase Inclusion in Silicon Carbide Powders

2015 ◽  
Vol 821-823 ◽  
pp. 100-103
Author(s):  
Ta Ching Hsiao ◽  
Shen Tsao ◽  
Sergey Nagalyuk ◽  
Evgeny Mokhov
Keyword(s):  
Silicon Carbide ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Element Distribution ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Dual Beam ◽  
Metal Doped ◽  
Dopant Element

A specific transition metal is used as a dopant element in silicon carbide powders to create the compensation effect. According to ab-initio simulation, vanadium, chromium, and manganese-induced compensation decrease the lifetime of the acceptor carrier and cause higher resistance when boron is the main impurity. Since the silicon carbide lattice has low solubility, excess metal precipitates on the surface of powders, particularly on the grain boundaries. The compositions of matrix and precipitation in the powders reveal obvious differences between the two areas. The X-ray diffraction (XRD) pattern shows the structure of VSi2, which indicates the existence of a second phase. Dual-beam focused ion beam (DBFIB) is used to further analyze the geography inside the powders. A cross-section view by DBFIB shows a second phase in the grains with a composition similar to that in the grain boundary. Metal-doped silicon carbide powders are used as starting materials to conduct crystal growth with better dopant element distribution.

scholarly journals Insight into the Characteristics of Novel Desmin-Immunopositive Perivascular Cells of the Anterior Pituitary Gland Using Transmission and Focused Ion Beam Scanning Electron Microscopy

2021 ◽  
Vol 22 (16) ◽  
pp. 8630
Author(s):  
Depicha Jindatip ◽  
Rebecca Wan-Yan Poh ◽  
Ken Fujiwara
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Cell Type ◽  
Insight Into ◽  
Scanning Electron

Recently, another new cell type was found in the perivascular space called a novel desmin-immunopositive perivascular (DIP) cell. However, the differences between this novel cell type and other nonhormone-producing cells have not been clarified. Therefore, we introduced several microscopic techniques to gain insight into the morphological characteristics of this novel DIP cell. We succeeded in identifying novel DIP cells under light microscopy using desmin immunocryosection, combining resin embedding blocks and immunoelectron microscopy. In conventional transmission electron microscopy, folliculostellate cells, capsular fibroblasts, macrophages, and pericytes presented a flat cisternae of rough endoplasmic reticulum, whereas those of novel DIP cells had a dilated pattern. The number of novel DIP cells was greatest in the intact rats, though nearly disappeared under prolactinoma conditions. Additionally, focused ion beam scanning electron microscopy showed that these novel DIP cells had multidirectional processes and some processes reached the capillary, but these processes did not tightly wrap the vessel, as is the case with pericytes. Interestingly, we found that the rough endoplasmic reticulum was globular and dispersed throughout the cytoplasmic processes after three-dimensional reconstruction. This study clearly confirms that novel DIP cells are a new cell type in the rat anterior pituitary gland, with unique characteristics.

scholarly journals CAR-1 and Trailer hitch: driving mRNP granule function at the ER?

2006 ◽  
Vol 173 (2) ◽  
pp. 159-163 ◽  
Author(s):  
Carolyn J. Decker ◽  
Roy Parker
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Fate ◽  
Translational Control ◽  
Translational Regulation ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Spindle Pole ◽  
Axis Formation ◽  
Cell Fate Determination ◽  
Messenger Rnas

The targeting of messenger RNAs (mRNAs) to specific subcellular sites for local translation plays an important role in diverse cellular and developmental processes in eukaryotes, including axis formation, cell fate determination, spindle pole regulation, cell motility, and neuronal synaptic plasticity. Recently, a new conserved class of Lsm proteins, the Scd6 family, has been implicated in controlling mRNA function. Depletion or mutation of members of the Scd6 family, Caenorhabditis elegans CAR-1 and Drosophila melanogaster trailer hitch, lead to a variety of developmental phenotypes, which in some cases can be linked to alterations in the endoplasmic reticulum (ER). Scd6/Lsm proteins are RNA binding proteins and are found in RNP complexes associated with translational control of mRNAs, and these complexes can colocalize with the ER. These findings raise the possibility that localization and translational regulation of mRNAs at the ER plays a role in controlling the organization of this organelle.

scholarly journals Contacts between the endoplasmic reticulum and other membranes in neurons

2017 ◽  
Vol 114 (24) ◽  
pp. E4859-E4867 ◽  
Author(s):  
Yumei Wu ◽  
Christina Whiteus ◽  
C. Shan Xu ◽  
Kenneth J. Hayworth ◽  
Richard J. Weinberg ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Cell Physiology ◽  
Organelle Biogenesis ◽  
Axon Terminals ◽  
Narrow Lumen ◽  
Dynamics And Control ◽  
Membrane Contacts ◽  
And Control

Close appositions between the membrane of the endoplasmic reticulum (ER) and other intracellular membranes have important functions in cell physiology. These include lipid homeostasis, regulation of Ca2+ dynamics, and control of organelle biogenesis and dynamics. Although these membrane contacts have previously been observed in neurons, their distribution and abundance have not been systematically analyzed. Here, we have used focused ion beam-scanning electron microscopy to generate 3D reconstructions of intracellular organelles and their membrane appositions involving the ER (distance ≤30 nm) in different neuronal compartments. ER–plasma membrane (PM) contacts were particularly abundant in cell bodies, with large, flat ER cisternae apposed to the PM, sometimes with a notably narrow lumen (thin ER). Smaller ER–PM contacts occurred throughout dendrites, axons, and in axon terminals. ER contacts with mitochondria were abundant in all compartments, with the ER often forming a network that embraced mitochondria. Small focal contacts were also observed with tubulovesicular structures, likely to be endosomes, and with sparse multivesicular bodies and lysosomes found in our reconstructions. Our study provides an anatomical reference for interpreting information about interorganelle communication in neurons emerging from functional and biochemical studies.

scholarly journals The architecture of the endoplasmic reticulum is regulated by the reversible lipid modification of the shaping protein CLIMP-63

2018 ◽  
Author(s):  
Patrick A. Sandoz ◽  
Robin A. Denhardt-Eriksson ◽  
Laurence Abrami ◽  
Luciano Abriata ◽  
Gard Spreemann ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Mammalian Cells ◽  
Cellular Localization ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Cysteine Residue ◽  
Relative Distribution ◽  
Post Translational Modification ◽  
Combining Data

AbstractThe endoplasmic reticulum (ER) has a complex morphology generated and maintained by membrane-shaping proteins and membrane energy minimization, though not much is known about how it is regulated. The architecture of this intracellular organelle is balanced between large, thin sheets that are densely packed in the perinuclear region and a connected network of branched, elongated tubules that extend throughout the cytoplasm. Sheet formation is known to involve the cytoskeleton-linking membrane protein 63 (CLIMP-63), though its regulation and the depth of its involvement remain unknown. Here we show that the post-translational modification of CLIMP-63 by the palmitoyltransferase ZDHHC6 controls the relative distribution of CLIMP-63 between the ER and the plasma membrane. By combining data-driven mathematical modeling, predictions, and experimental validation, we found that the attachment of a medium chain fatty acid, so-called S-palmitoylation, to the unique CLIMP-63 cytoplasmic cysteine residue drastically reduces its turnover rate, and thereby controls its abundance. Light microscopy and focused ion beam electron microcopy further revealed that enhanced CLIMP-63 palmitoylation leads to strong ER-sheet proliferation. Altogether, we show that ZDHHC6-mediated S-palmitoylation regulates the cellular localization of CLIMP-63, the morphology of the ER, and the interconversion of ER structural elements in mammalian cells through its action on the CLIMP-63 protein.Significance StatementEukaryotic cells subcompartmentalize their various functions into organelles, the shape of each being specific and necessary for its proper role. However, how these shapes are generated and controlled is poorly understood. The endoplasmic reticulum is the largest membrane-bound intracellular compartment, accounting for more than 50% of all cellular membranes. We found that the shape and quantity of its sheet-like structures are controlled by a specific protein, cytoskeleton-linking membrane protein 63, through the acquisition of a lipid chain attached by an enzyme called ZDHHC6. Thus, by modifying the ZDHHC6 amounts, a cell can control the shape of its ER. The modeling and prediction technique used herein also provides a method for studying the interconnected function of other post-translational modifications in organelles.

Deformation of Biomedical AuCuAl-Based Shape Memory Alloy Micropillars

MRS Advances ◽  
2017 ◽  
Vol 2 (26) ◽  
pp. 1411-1415 ◽  
Author(s):  
Akira Umise ◽  
Rui Serizawa ◽  
Sari Yanagida ◽  
Kenji Goto ◽  
Masaki Tahara ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Recovery ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Transformation Strain ◽  
Xrd Analysis ◽  
Second Phase ◽  
Shape Memory Property ◽  
Good Shape

ABSTRACTThe deformation behavior and shape recovery of an Fe-added AuCuAl shape memory alloy micropillar were investigated. XRD analysis revealed that Au-28Cu-22Al-2Fe (at.%) alloy contained a second phase which was evaluated to be α-Fe (bcc). SEM observation also confirmed the second phase at the surface of the micropillar specimen. A polycrystalline micropillar with 20 x 20 x 40μm rectangular was fabricated by a focused ion beam (FIB) system, and micro compress test was performed at room temperature. It was found that the yield stress of micropillar showed 50MPa, which must correspond to stress for inducing martensite. After the heating of the compressed micropillar, 1.75% shape recovery was recognized which is comparable to the transformation strain. Then, the Fe-added AuCuAl micropillar was concluded to possess good shape memory property, and thus this alloy may be suitable for small endovascular treatment which requires good X-ray radiography.

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