scholarly journals Longitudinal tracking of neuronal mitochondria delineates PINK1/Parkin-dependent mechanisms of mitochondrial recycling and degradation

2021 ◽  
Vol 7 (32) ◽  
pp. eabf6580
Author(s):  
Huihui Li ◽  
Zak Doric ◽  
Amandine Berthet ◽  
Danielle M. Jorgens ◽  
Mai K. Nguyen ◽  
...  
Keyword(s):  
Quality Control ◽  
Light And Electron Microscopy ◽  
Time Lapse ◽  
Dopamine Neurons ◽  
Autophagosome Formation ◽  
Mitochondrial Quality Control ◽  
Time Lapse Microscopy ◽  
Longitudinal Tracking ◽  
The Matrix ◽  
Kinetics Of

Altered mitochondrial quality control and dynamics may contribute to neurodegenerative diseases, including Parkinson’s disease, but we understand little about these processes in neurons. We combined time-lapse microscopy and correlative light and electron microscopy to track individual mitochondria in neurons lacking the fission-promoting protein dynamin-related protein 1 (Drp1) and delineate the kinetics of PINK1-dependent pathways of mitochondrial quality control. Depolarized mitochondria recruit Parkin to the outer mitochondrial membrane, triggering autophagosome formation, rapid lysosomal fusion, and Parkin redistribution. Unexpectedly, these mitolysosomes are dynamic and persist for hours. Some are engulfed by healthy mitochondria, and others are deacidified before bursting. In other cases, Parkin is directly recruited to the matrix of polarized mitochondria. Loss of PINK1 blocks Parkin recruitment, causes LC3 accumulation within mitochondria, and exacerbates Drp1KO toxicity to dopamine neurons. These results define a distinct neuronal mitochondrial life cycle, revealing potential mechanisms of mitochondrial recycling and signaling relevant to neurodegeneration.

scholarly journals Systematic kinetic analysis of mitotic dis- and reassembly of the nuclear pore in living cells

2008 ◽  
Vol 180 (5) ◽  
pp. 857-865 ◽  
Author(s):  
Elisa Dultz ◽  
Esther Zanin ◽  
Claudia Wurzenberger ◽  
Marion Braun ◽  
Gwénaël Rabut ◽  
...  
Keyword(s):  
Time Lapse ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Time Lapse Microscopy ◽  
Sequence Of Events ◽  
Distinct Mechanism ◽  
Dividing Cells ◽  
Higher Eukaryotes ◽  
Pore Complexes ◽  
Kinetics Of

During mitosis in higher eukaryotes, nuclear pore complexes (NPCs) disassemble in prophase and are rebuilt in anaphase and telophase. NPC formation is hypothesized to occur by the interaction of mitotically stable subcomplexes that form defined structural intermediates. To determine the sequence of events that lead to breakdown and reformation of functional NPCs during mitosis, we present here our quantitative assay based on confocal time-lapse microscopy of single dividing cells. We use this assay to systematically investigate the kinetics of dis- and reassembly for eight nucleoporin subcomplexes relative to nuclear transport in NRK cells, linking the assembly state of the NPC with its function. Our data establish that NPC assembly is an ordered stepwise process that leads to import function already in a partially assembled state. We furthermore find that nucleoporin dissociation does not occur in the reverse order from binding during assembly, which may indicate a distinct mechanism.

scholarly journals Mitochondrial division occurs concurrently with autophagosome formation but independently of Drp1 during mitophagy

2016 ◽  
Vol 215 (5) ◽  
pp. 649-665 ◽  
Author(s):  
Shun-ichi Yamashita ◽  
Xiulian Jin ◽  
Kentaro Furukawa ◽  
Maho Hamasaki ◽  
Akiko Nezu ◽  
...  
Keyword(s):  
Quality Control ◽  
Mammalian Cells ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Temporal Analysis ◽  
Live Cell ◽  
Autophagosome Formation ◽  
Mitochondrial Quality Control ◽  
Mitochondrial Division ◽  
Division Factor

Mitophagy is thought to play an important role in mitochondrial quality control. Mitochondrial division is believed to occur first, and autophagosome formation subsequently occurs to enwrap mitochondria as a process of mitophagy. However, there has not been any temporal analysis of mitochondrial division and autophagosome formation in mitophagy. Therefore, the relationships among these processes remain unclear. We show that the mitochondrial division factor Dnm1 in yeast or Drp1 in mammalian cells is dispensable for mitophagy. Autophagosome formation factors, such as FIP200, ATG14, and WIPIs, were essential for the mitochondrial division for mitophagy. Live-cell imaging showed that isolation membranes formed on the mitochondria. A small portion of the mitochondria then divided from parental mitochondria simultaneously with the extension of isolation membranes and autophagosome formation. These findings suggest the presence of a mitophagy process in which mitochondrial division for mitophagy is accomplished together with autophagosome formation.

Effects of EDTA, Hyaluronidase and Collagenase on Epiphyseal Cartilage Matrix

1968 ◽  
Vol 26 ◽  
pp. 56-57
Author(s):  
H. Clarke Anderson ◽  
Priscilla R. Coulter
Keyword(s):  
Light And Electron Microscopy ◽  
Matrix Vesicles ◽  
Cartilage Matrix ◽  
Collagen Fibrils ◽  
Epiphyseal Cartilage ◽  
Dense Matrix ◽  
Type Iv ◽  
Bovine Testicular Hyaluronidase ◽  
The Matrix ◽  
Testicular Hyaluronidase

Epiphyseal cartilage matrix contains fibrils and particles of at least 5 different types: 1. Banded collagen fibrils, present throughout the matrix, but not seen in the lacunae. 2. Non-periodic fine fibrils <100Å in diameter (Fig. 1), which are most notable in the lacunae, and may represent immature collagen. 3. Electron dense matrix granules (Fig. 1) which are often attached to fine fibrils and collagen fibrils, and probably contain protein-polysaccharide although the possibility of a mineral content has not been excluded. 4. Matrix vesicles (Fig. 2) which show a selective distribution throughout the epiphysis, and may play a role in calcification. 5. Needle-like apatite crystals (Fig. 2).Blocks of formalin-fixed epiphysis from weanling mice were digested with the following agents in 0.1M phosphate buffer: a) 5% ethylenediaminetetraacetate (EDTA) at pH 8.3, b) 0.015% bovine testicular hyaluronidase (Sigma, type IV, 750 units/mg) at pH 5.5, and c) 0.1% collagenase (Worthington, chromatograhically pure, 200 units/mg) at pH 7.4. All digestions were carried out at 37°C overnight. Following digestion tissues were examined by light and electron microscopy to determine changes in the various fibrils and particles of the matrix.

High-resolution observations of metastable γ’ precipitation in Al-15at.%Ag

1996 ◽  
Vol 54 ◽  
pp. 1004-1005
Author(s):  
N. V. Larcher ◽  
I. G. Solorzano
Keyword(s):  
Discontinuous Precipitation ◽  
Equilibrium Phase ◽  
Quantitative Description ◽  
Present Contribution ◽  
Α Phase ◽  
The Matrix ◽  
Aging Sequence ◽  
Matrix Precipitation ◽  
Considerable Detail ◽  
Kinetics Of

It is currently well established that, for an Al-Ag alloy quenched from the α phase and aged within the metastable solvus, the aging sequence is: supersaturated α → GP zones → γ’ → γ (Ag2Al). While GP zones and plate-shaped γ’ are metastable phases, continuously distributed in the matrix, formation of the equilibrium phase γ takes place at grain boundaries by discontinuous precipitation (DP). The crystal structure of both γ’ and γ is hep with the following orientation relationship with respect to the fee α matrix: {0001}γ′,γ // {111}α, <1120>γ′,γ, // <110>α.The mechanisms and kinetics of continuous matrix precipitation (CMP) in dilute Al-Ag alloys have been studied in considerable detail. The quantitative description of DP kinetics, however, has received less attention. The present contribution reports the microstructural evolution resulting from aging an Al-Ag alloy with Ag content higher than those previously reported in the literature, focusing the observations of γ' plate-shaped metastable precipitates.

Experience of using time-lapse microscopy in IVF and ICSI programs

2020 ◽  
pp. 47-50
Author(s):  
N. V. Saraeva ◽  
N. V. Spiridonova ◽  
M. T. Tugushev ◽  
O. V. Shurygina ◽  
A. I. Sinitsyna
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Selection Procedure ◽  
Time Lapse ◽  
Single Embryo Transfer ◽  
Main Group ◽  
Clinical Pregnancy ◽  
Control Group ◽  
Time Lapse Microscopy

In order to increase the pregnancy rate in the assisted reproductive technology, the selection of one embryo with the highest implantation potential it is very important. Time-lapse microscopy (TLM) is a tool for selecting quality embryos for transfer. This study aimed to assess the benefits of single-embryo transfer of autologous oocytes performed on day 5 of embryo incubation in a TLM-equipped system in IVF and ICSI programs. Single-embryo transfer following incubation in a TLM-equipped incubator was performed in 282 patients, who formed the main group; the control group consisted of 461 patients undergoing single-embryo transfer following a traditional culture and embryo selection procedure. We assessed the quality of transferred embryos, the rates of clinical pregnancy and delivery. The groups did not differ in the ratio of IVF and ICSI cycles, average age, and infertility factor. The proportion of excellent quality embryos for transfer was 77.0% in the main group and 65.1% in the control group (p = 0.001). In the subgroup with receiving eight and less oocytes we noted the tendency of receiving more quality embryos in the main group (р = 0.052). In the subgroup of nine and more oocytes the quality of the transferred embryos did not differ between two groups. The clinical pregnancy rate was 60.2% in the main group and 52.9% in the control group (p = 0.057). The delivery rate was 45.0% in the main group and 39.9% in the control group (p > 0.050).

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