scholarly journals Vesicular trafficking in characean green algae and the possible involvement of a VAMP72-family protein

2014 ◽  
Vol 9 (4) ◽  
pp. e28466 ◽  
Author(s):  
Marion C Hoepflinger ◽  
Christina Hametner ◽  
Takashi Ueda ◽  
Ilse Foissner
Keyword(s):  
Green Algae ◽  
Vesicular Trafficking ◽  
Family Protein

scholarly journals Sterol flow between the plasma membrane and the endosome is regulated by the LAM family protein Ltc1

2019 ◽  
Author(s):  
Magdalena Marek ◽  
Vincent Vincenzetti ◽  
Sophie G. Martin
Keyword(s):  
Plasma Membrane ◽  
Membrane Integrity ◽  
Physiological Role ◽  
Time Lapse ◽  
Vesicular Trafficking ◽  
Protein Oligomerization ◽  
Family Protein ◽  
State Growth ◽  
Eukaryotic Organisms ◽  
Time Lapse Imaging

AbstractSterols are crucial components of biological membranes that help maintain membrane integrity and regulate various processes such as endocytosis, protein oligomerization and signaling. Although synthetized in the ER, sterols are at highest concentrations at the plasma membrane (PM) in all eukaryotic organisms. Here, by applying a genetically encoded sterol biosensor (D4H), we visualize a sterol flow between PM and endosomes in the fission yeast Schizosaccharomyces pombe. While D4H is detected at the PM during steady-state growth, inhibition of Arp2/3-dependent F-actin assembly unexpectedly promotes the reversible re-localization of the probe to internal sterol rich compartments (STRIC), as shown by correlative light-electron microscopy. Time-lapse imaging identifies STRIC as a late secretory, endosomal compartment labelled by the synaptobrevin Syb1. Retrograde sterol internalization to STRIC is independent of endocytosis or an intact Golgi. Instead, it depends on Ltc1, a LAM/StARkin-family protein that localizes to ER-PM contact sites. In ltc1Δ, sterols over-accumulate at the PM, which forms extended ER-interacting invaginations, indicating that sterol transfer by Ltc1 contributes to PM size homeostasis. Anterograde sterol movement from STRIC is independent of canonical vesicular trafficking components but requires Arp2/3 activity, suggesting a novel physiological role for this complex. Thus, transfer routes orthogonal to vesicular trafficking govern the retrograde and anterograde flow of sterols in the cell.

Intracellular Vesicular Trafficking of Tyrosinase Gene Family Protein in Eu- and Pheomelanosome Biogenesis

2000 ◽  
Vol 13 ◽  
pp. 110-117 ◽  
Author(s):  
KOWICHI JIMBOW ◽  
CHEN HUA ◽  
PAUL F. GOMEZ ◽  
KUNINORI HIROSAKI ◽  
KYOKA SHINODA ◽  
...  
Keyword(s):  
Gene Family ◽  
Vesicular Trafficking ◽  
Tyrosinase Gene ◽  
Family Protein

scholarly journals Sterol biosensor reveals LAM-family Ltc1-dependent sterol flow to endosomes upon Arp2/3 inhibition

2020 ◽  
Vol 219 (6) ◽  
Author(s):  
Magdalena Marek ◽  
Vincent Vincenzetti ◽  
Sophie G. Martin
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Biological Membranes ◽  
Time Lapse ◽  
Vesicular Trafficking ◽  
Actin Assembly ◽  
Contact Sites ◽  
Family Protein

Sterols are crucial components of biological membranes, which are synthetized in the ER and accumulate in the plasma membrane (PM). Here, by applying a genetically encoded sterol biosensor (D4H), we visualize a sterol flow between PM and endosomes in the fission yeast Schizosaccharomyces pombe. Using time-lapse and correlative light-electron microscopy, we found that inhibition of Arp2/3-dependent F-actin assembly promotes the reversible relocalization of D4H from the PM to internal sterol-rich compartments (STRIC) labeled by synaptobrevin Syb1. Retrograde sterol internalization to STRIC is independent of endocytosis or an intact Golgi, but depends on Ltc1, a LAM/StARkin-family protein localized to ER-PM contact sites. The PM in ltc1Δ cells over-accumulates sterols and upon Arp2/3 inhibition forms extended ER-interacting invaginations, indicating that sterol transfer contributes to PM size homeostasis. Anterograde sterol movement from STRIC is independent of canonical vesicular trafficking but requires Arp2/3, suggesting a novel role for this complex. Thus, transfer routes orthogonal to vesicular trafficking govern the flow of sterols in the cell.

Freeze-Fracture Replication in the Ultrastructure of Blue-Green Algae

1967 ◽  
Vol 25 ◽  
pp. 74-75
Author(s):  
L. V. Leak
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Green Algae ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Electron Microscopic ◽  
Photosynthetic Membranes ◽  
Blue Green Algae ◽  
Cell Biol ◽  
Cellular Components

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.

A Scanning Electron Microscopic Study of Pro-Vascular Cellular Morphology in Chaetophora Incressata

1985 ◽  
Vol 43 ◽  
pp. 638-639
Author(s):  
A. E. Hotchkiss ◽  
A. T. Hotchkiss ◽  
R. P. Apkarian
Keyword(s):  
Green Algae ◽  
Vascular Plants ◽  
Vascular System ◽  
Higher Plants ◽  
Wall Structure ◽  
Electron Microscopic ◽  
Physiological Processes ◽  
Scanning Electron Microscopic Study ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

Multicellular green algae may be an ancestral form of the vascular plants. These algae exhibit cell wall structure, chlorophyll pigmentation, and physiological processes similar to those of higher plants. The presence of a vascular system which provides water, minerals, and nutrients to remote tissues in higher plants was believed unnecessary for the algae. Among the green algae, the Chaetophorales are complex highly branched forms that might require some means of nutrient transport. The Chaetophorales do possess apical meristematic groups of cells that have growth orientations suggestive of stem and root positions. Branches of Chaetophora incressata were examined by the scanning electron microscope (SEM) for ultrastructural evidence of pro-vascular transport.

The Influence of Lead and Copper on Some Indices of Vital Activity of Green and Blue-green Algae

2001 ◽  
Vol 37 (2) ◽  
pp. 13
Author(s):  
V. A. Medved'
Keyword(s):  
Green Algae ◽  
Vital Activity ◽  
Blue Green Algae

Peculiarities of Energetic, Nitrogen, and Phosphorus Metabolism in Blue-Green Algae under the Influence of Humic Acids

2008 ◽  
Vol 44 (6) ◽  
pp. 74-82
Author(s):  
O. V. Sinyuk ◽  
V. V. Grubinko ◽  
P. D. Klochenko ◽  
T. A. Vasilchuk
Keyword(s):  
Green Algae ◽  
Humic Acids ◽  
Phosphorus Metabolism ◽  
Nitrogen And Phosphorus ◽  
Blue Green Algae

Peculiarities of Accumulation of Proteins, Carbohydrates and Lipids in the Cells of Green Algae under Different Light Conditions and Photoperiod

2020 ◽  
Vol 56 (3) ◽  
pp. 97-104
Author(s):  
V. O. Medved ◽  
Z. N. Gorbunova ◽  
T. V. Vitovetska
Keyword(s):  
Green Algae ◽  
Light Conditions
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