scholarly journals Analysis of Cell–Cell Bridges in Haloferax volcanii Using Electron Cryo-Tomography Reveal a Continuous Cytoplasm and S-Layer

2021 ◽  
Vol 11 ◽  
Author(s):  
Shamphavi Sivabalasarma ◽  
Hanna Wetzel ◽  
Phillip Nußbaum ◽  
Chris van der Does ◽  
Morgan Beeby ◽  
...  
Keyword(s):  
Halophilic Archaea ◽  
Time Lapse ◽  
Intercellular Bridge ◽  
Helical Structures ◽  
Macromolecular Complexes ◽  
Time Lapse Microscopy ◽  
A Cell ◽  
Cellular Components ◽  
Shed Light ◽  
Cell Cell

Halophilic archaea have been proposed to exchange DNA and proteins using a fusion-based mating mechanism. Scanning electron microscopy previously suggested that mating involves an intermediate state, where cells are connected by an intercellular bridge. To better understand this process, we used electron cryo-tomography (cryoET) and fluorescence microscopy to visualize cells forming these intercellular bridges. CryoET showed that the observed bridges were enveloped by an surface layer (S-layer) and connected mating cells via a continuous cytoplasm. Macromolecular complexes like ribosomes and unknown thin filamentous helical structures were visualized in the cytoplasm inside the bridges, demonstrating that these bridges can facilitate exchange of cellular components. We followed formation of a cell–cell bridge by fluorescence time-lapse microscopy between cells at a distance of 1.5 μm. These results shed light on the process of haloarchaeal mating and highlight further mechanistic questions.

scholarly journals Analysis of cell-cell bridges in Haloferax volcanii using Electron cryo-tomography reveal a continuous cytoplasm and S-layer

2020 ◽  
Author(s):  
Shamphavi Sivabalasarma ◽  
Hanna Wetzel ◽  
Phillip Nußbaum ◽  
Chris van der Does ◽  
Morgan Beeby ◽  
...  
Keyword(s):  
Halophilic Archaea ◽  
Time Lapse ◽  
Intercellular Bridge ◽  
Helical Structures ◽  
Macromolecular Complexes ◽  
A Cell ◽  
Electron Cryotomography ◽  
Cellular Components ◽  
Shed Light ◽  
Cell Cell

Halophilic archaea exchange DNA and proteins using a fusion-based mating mechanism. Scanning electron microscopy previously suggested that mating involves an intermediate state, where cells are connected by an intercellular bridge. To better understand this process, we used electron cryotomography and fluorescence microscopy to visualize cells forming these intercellular bridges. Electron cryo-tomography showed that the observed bridges were enveloped by an S-layer and connected mating cells via a continuous cytoplasm. Macromolecular complexes like ribosomes and unknown thin filamentous helical structures were visualized in the cytoplasm inside the bridges, demonstrating that these bridges can facilitate exchange of cellular components. We followed formation of a cell-cell bridge by fluorescence time-lapse microscopy between cells at a distance of 1.5 µm. These results shed light on the process of haloarchaeal mating and highlight further mechanistic questions.

scholarly journals Partitioning and Exocytosis of Secretory Granules during Division of PC12 Cells

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Nickolay Vassilev Bukoreshtliev ◽  
Erlend Hodneland ◽  
Tilo Wolf Eichler ◽  
Patricia Eifart ◽  
Amin Rustom ◽  
...  
Keyword(s):  
Cell Division ◽  
Pc12 Cells ◽  
Secretory Granules ◽  
Time Lapse ◽  
Intercellular Bridge ◽  
Time Lapse Microscopy ◽  
Interphase Cells ◽  
Molecular Machinery ◽  
Spindle Microtubules ◽  
Single Granule

The biogenesis, maturation, and exocytosis of secretory granules in interphase cells have been well documented, whereas the distribution and exocytosis of these hormone-storing organelles during cell division have received little attention. By combining ultrastructural analyses and time-lapse microscopy, we here show that, in dividing PC12 cells, the prominent peripheral localization of secretory granules is retained during prophase but clearly reduced during prometaphase, ending up with only few peripherally localized secretory granules in metaphase cells. During anaphase and telophase, secretory granules exhibited a pronounced movement towards the cell midzone and, evidently, their tracks colocalized with spindle microtubules. During cytokinesis, secretory granules were excluded from the midbody and accumulated at the bases of the intercellular bridge. Furthermore, by measuring exocytosis at the single granule level, we showed, that during all stages of cell division, secretory granules were competent for regulated exocytosis. In conclusion, our data shed new light on the complex molecular machinery of secretory granule redistribution during cell division, which facilitates their release from the F-actin-rich cortex and active transport along spindle microtubules.

SEGMENTATION AND TRACKING OF PROGENITOR CELLS IN TIME LAPSE MICROSCOPY

2012 ◽  
Vol 12 (01) ◽  
pp. 1250008
Author(s):  
R. M. SURESH ◽  
N. JAYALAKSHMI
Keyword(s):  
Progenitor Cells ◽  
Neural Progenitor Cells ◽  
Time Lapse ◽  
Neural Progenitor ◽  
Image Sequences ◽  
Complex Nature ◽  
Watershed Algorithm ◽  
Automatic Quantification ◽  
Time Lapse Microscopy ◽  
A Cell

In this paper the neural progenitor cells in a time-lapse microscopic sequence are analyzed to find position, shape, motility, and ancestor of each cell in the frame. Because of the complex nature of cells, the ability to distinguish a cell from the background of an image for automatic quantification remains a challenging task. By using morphological techniques, the blob-like objects are selected. The cells are detected using h-maxima transform and the cell contours are selected using watershed algorithm. The cells between image sequences are tracked using multiple matching object method based on modified Mahalanobis algorithm. The proposed method has been successfully applied to a large number of images and showed promising results for tracking cells between consecutive images.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

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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