Freeze-etching observations on the characteristic arrangement of intramembranous particles in the apical plasma membrane of the thyroid follicular cell in TSH-treated mice

Abstract Background Monogeneans, in general, show a range of unique adaptations to a parasitic lifestyle, making this group enormously diverse. Due to their unique biological properties, diplozoid monogeneans represent an attractive model group for various investigations on diverse biological interactions. However, despite numerous studies, there are still gaps in our knowledge of diplozoid biology and morphofunctional adaptations. Results In this study, we provide a comprehensive microscopic analysis of systems/structures involved in niche searching, sensing and self-protection against the host environment, and excretory/secretory processes in Eudiplozoon nipponicum. Freeze-etching enabled us to detect syncytium organisational features not visible by TEM alone, such as the presence of a membrane subjacent to the apical plasma membrane (separated by a dense protein layer) and a lack of basal plasma membrane. We located several types of secretory/excretory vesicles and bodies, including those attached to the superficial membranes of the tegument. Giant unicellular glands were seen accumulating predominantly in the apical forebody and hindbody haptor region. Muscle layer organisation differed from that generally described, with the outer circular and inner longitudinal muscles being basket-like interwoven by diagonal muscles with additional perpendicular muscles anchored to the tegument. Abundant muscles within the tegumentary ridges were detected, which presumably assist in fixing the parasite between the gill lamellae. Freeze-etching, alongside transmission electron and confocal microscopy with tubulin labelling, enabled visualisation of the protonephridia and nervous system, including the peripheral network and receptor innervation. Three types of receptor were identified: 1) uniciliated sensory endings with a subtle (or missing) tegumentary rim, 2) obviously raised uniciliated receptors with a prominent tegumentary rim (packed with massive innervation and muscles) and 3) non-ciliated papillae (restricted to the hindbody lateral region). Conclusions This study points to specific morphofunctional adaptations that have evolved in diplozoid monogeneans to confront their fish host. We clearly demonstrate that the combination of different microscopic techniques is beneficial and can reveal hidden differences, even in much-studied model organisms such as E. nipponicum.

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Eudiplozoon Nipponicum: Morphofunctional Adaptations of Diplozoid Monogeneans for Confronting Their Host

10.21203/rs.3.rs-82669/v2 ◽

2020 ◽

Author(s):

Andrea Valigurová ◽

Naděžda Vaškovicová ◽

Milan Gelnar ◽

Magdaléna Kováčiková ◽

Iveta Hodová

Keyword(s):

Plasma Membrane ◽

Microscopic Analysis ◽

Muscle Layer ◽

Biological Properties ◽

Fish Host ◽

Model Organisms ◽

Apical Plasma Membrane ◽

Biological Interactions ◽

Freeze Etching ◽

Eudiplozoon Nipponicum

Abstract Background: Monogeneans, in general, show a range of unique adaptations to a parasitic lifestyle, making this group enormously diverse. Due to their unique biological properties, diplozoid monogeneans represent an attractive model group for various investigations on diverse biological interactions. However, despite numerous studies, there are still gaps in our knowledge of diplozoid biology and morphofunctional adaptation.Results: In this study, we provide a complex microscopic analysis of systems/structures involved in niche searching, sensing and self-protection against the host environment, and excretory/secretory processes in Eudiplozoon nipponicum. Freeze-etching enabled us to detect syncytium organisational features not visible by TEM alone, such as the presence of a membrane subjacent to the apical plasma membrane (separated by a dense protein layer) and a lack of basal plasma membrane. We located several types of secretory/excretory vesicles and bodies, including those attached to the superficial membranes of the tegument. Giant unicellular glands were seen accumulating predominantly in the apical forebody and hindbody haptor region. Muscle layer organisation differed from that generally described, with the outer circular and inner longitudinal muscles being basket-like interwoven by diagonal muscles with additional perpendicular muscles anchored to the tegument. Abundant muscles within the tegumentary ridges were detected, which presumably assist in fixing the parasite between the gill lamellae. Freeze-etching, alongside transmission electron and confocal microscopy with tubulin labelling, enabled visualisation of the protonephridia and nervous system, including the peripheral network and receptor innervation. Three types of receptor were identified: 1) uniciliated sensory endings with a less prominent (or missing) tegumentary rim, 2) obviously raised uniciliated receptors with a prominent tegumentary rim (packed with massive innervation and muscles) and 3) non-ciliated papillae (restricted to the hindbody lateral region). Conclusions: This study points to specific morphofunctional adaptations that have evolved in diplozoid monogeneans to confront their fish host. We clearly demonstrate that the combination of different microscopic techniques is beneficial and can reveal hidden differences, even in much-studied model organisms such as E. nipponicum.

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Eudiplozoon Nipponicum : Morphofunctional Adaptations of Diplozoid Monogeneans for Confronting Their Host

10.21203/rs.3.rs-82669/v1 ◽

2020 ◽

Author(s):

Andrea Valigurová ◽

Naděžda Vaškovicová ◽

Milan Gelnar ◽

Magdaléna Kováčiková ◽

Iveta Hodová

Keyword(s):

Plasma Membrane ◽

Microscopic Analysis ◽

Muscle Layer ◽

Biological Properties ◽

Fish Host ◽

Model Organisms ◽

Apical Plasma Membrane ◽

Biological Interactions ◽

Freeze Etching ◽

Eudiplozoon Nipponicum

Abstract BackgroundMonogeneans, in general, show a range of unique adaptations to a parasitic lifestyle, making this group enormously diverse. Due to their unique biological properties, diplozoid monogeneans represent an attractive model group for various investigations on diverse biological interactions. However, despite numerous studies, there are still gaps in our knowledge of diplozoid biology and morphofunctional adaptation.ResultsIn this study, we provide a complex microscopic analysis of systems/structures involved in niche searching, sensing and self-protection against the host environment, and excretory/secretory processes in Eudiplozoon nipponicum. Freeze-etching enabled us to detect syncytium organisational features not visible by TEM alone, such as the presence of a membrane subjacent to the apical plasma membrane (separated by a dense protein layer) and a lack of basal plasma membrane. We located several types of secretory/excretory vesicles and bodies, including those attached to the superficial membranes of the tegument. Giant unicellular glands were seen accumulating predominantly in the apical forebody and hindbody haptor region. Muscle layer organisation differed from that generally described, with the outer circular and inner longitudinal muscles being basket-like interwoven by diagonal muscles with additional perpendicular muscles anchored to the tegument. Abundant muscles within the tegumentary ridges were detected, which presumably assist in fixing the parasite between the gill lamellae. Freeze-etching, alongside transmission electron and confocal microscopy with tubulin labelling, enabled visualisation of the protonephridia and nervous system, including the peripheral network and receptor innervation. Three types of receptor were identified: 1) uniciliated sensory endings with a less prominent (or missing) tegumentary rim, 2) obviously raised uniciliated receptors with a prominent tegumentary rim (packed with massive innervation and muscles) and 3) non-ciliated papillae (restricted to the hindbody lateral region). ConclusionsThis study points to specific morphofunctional adaptations that have evolved in diplozoid monogeneans to confront their fish host. We clearly demonstrate that the combination of different microscopic techniques is beneficial and can reveal hidden differences, even in much-studied model organisms such as E. nipponicum.

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Relationships between intramembranous particles and surface coat carbohydrates in cells of a compact tissue

Journal of Cell Science ◽

10.1242/jcs.64.1.123 ◽

1983 ◽

Vol 64 (1) ◽

pp. 123-136

Author(s):

C.R. Murphy ◽

J.G. Swift

Keyword(s):

Plasma Membrane ◽

Epithelial Cells ◽

Apical Plasma Membrane ◽

Tissue Cell ◽

Surface Coat ◽

Intramembranous Particles ◽

Structural Relationships ◽

Surface Carbohydrates ◽

In Cells

The structural relationships between intramembranous particles (IMPs) and surface carbohydrates have been studied in cells of a compact tissue—uterine epithelial cells—using an in vivo technique. This involves introducing small amounts of glycerol into the uterine lumen of anaesthetized rats. The treatment results in extensive aggregation of IMPs in the apical plasma membrane of the epithelial cells, but no change in the distribution of several surface carbohydrates could be detected. Our findings indicate that, in this case, the carbohydrates are not the surface expression of the IMPs, which are generally believed to represent integral membrane proteins. We suggest that the structural relationships between IMPs and surface carbohydrates in the plasma membrane of this compact tissue cell are more similar to those in membranes of free-floating nucleated cells than to those in the much-studied erythrocyte membrane.

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Ultrastructure of Amphiuma distal nephron: evidence for cellular heterogeneity

AJP Cell Physiology ◽

10.1152/ajpcell.1989.256.4.c849 ◽

1989 ◽

Vol 256 (4) ◽

pp. C849-C857 ◽

Cited By ~ 10

Author(s):

D. Biemesderfer ◽

B. Stanton ◽

J. B. Wade ◽

M. Kashgarian ◽

G. Giebisch

Keyword(s):

Plasma Membrane ◽

Tight Junction ◽

Apical Membrane ◽

Membrane Surface ◽

Distal Tubule ◽

Apical Plasma Membrane ◽

Distal Nephron ◽

Principal Cells ◽

Intramembranous Particles ◽

Collecting Tubule

To obtain more information on the ultrastructure of the distal nephron of the salamander, Amphiuma, we conducted freeze-fracture electron microscopy and morphometric experiments. In the early distal tubule, the organization of the tight junction is variable, containing from one to two strands in the proximal region and four strands in distal regions. The length density of the tight junction in this segment varies from greater than 60 m/cm2 of apical membrane surface to less than 10/cm2 of apical membrane surface. These observations agree with a previous study demonstrating that the junction of this segment exhibits considerable axial heterogeneity. The junctions of the late distal tubule and collecting tubule are more complex. In the late distal tubule, the tight junction is composed of 6-8 strands, whereas the tight junction of the collecting tubule is composed of 8-12 strands. The collecting tubule contains principal cells and two types of intercalated cells: alpha and beta. The alpha-cells contain a high density of rod-shaped particles in the apical plasma membrane and in membranes of apical cytoplasmic vesicles. The beta-cells contain rod-shaped particles only in the basolateral membrane. In principal cells, we observed a novel organization of intramembranous particles within the apical plasma membrane. A model describing the relationship of the two types of intramembranous particles within the membrane is presented. This study demonstrates that the amphibian and mammalian distal nephron share many morphological characteristics including cellular and axial heterogeneity.

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Redistribution of a rab3-like GTP-binding protein from secretory granules to the Golgi complex in pancreatic acinar cells during regulated exocytosis

The Journal of Cell Biology ◽

10.1083/jcb.124.1.43 ◽

1994 ◽

Vol 124 (1) ◽

pp. 43-53 ◽

Cited By ~ 54

Author(s):

BP Jena ◽

FD Gumkowski ◽

EM Konieczko ◽

GF von Mollard ◽

R Jahn ◽

...

Keyword(s):

Plasma Membrane ◽

Golgi Complex ◽

Binding Protein ◽

Secretory Granules ◽

Acinar Cells ◽

Pancreatic Acinar Cells ◽

Apical Plasma Membrane ◽

Gtp Binding Protein ◽

Regulated Exocytosis ◽

Gtp Binding

Regulated secretion from pancreatic acinar cells occurs by exocytosis of zymogen granules (ZG) at the apical plasmalemma. ZGs originate from the TGN and undergo prolonged maturation and condensation. After exocytosis, the zymogen granule membrane (ZGM) is retrieved from the plasma membrane and ultimately reaches the TGN. In this study, we analyzed the fate of a low M(r) GTP-binding protein during induced exocytosis and membrane retrieval using immunoblots as well as light and electron microscopic immunocytochemistry. This 27-kD protein, identified by a monoclonal antibody that recognizes rab3A and B, may be a novel rab3 isoform. In resting acinar cells, the rab3-like protein was detected primarily on the cytoplasmic face of ZGs, with little labeling of the Golgi complex and no significant labeling of the apical plasmalemma or any other intracellular membranes. Stimulation of pancreatic lobules in vitro by carbamylcholine for 15 min, resulted in massive exocytosis that led to a near doubling of the area of the apical plasma membrane. However, no relocation of the rab3-like protein to the apical plasmalemma was seen. After 3 h of induced exocytosis, during which time approximately 90% of the ZGs is released, the rab3-like protein appeared to translocate to small vesicles and newly forming secretory granules in the TGN. No significant increase of the rab3-like protein was found in the cytosolic fraction at any time during stimulation. Since the protein is not detected on the apical plasmalemma after stimulation, we conclude that recycling may involve a membrane dissociation-association cycle that accompanies regulated exocytosis.

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