Some ultrastructural features of the nuchal organ of Daphnia magna Straus (Crustacea: Branchiopoda)

1982 ◽  
Vol 60 (6) ◽  
pp. 1257-1264 ◽  
Author(s):  
K. Halcrow
Keyword(s):  
Daphnia Magna ◽  
Plasma Membranes ◽  
Cell Types ◽  
Apical Surface ◽  
Dark Cells ◽  
First Instar ◽  
Basal Plasma

The ultrastructure of the nuchal organ of first instar of Daphnia magna is similar to that described in the literature for presumed ion-transporting tissues in other crustaceans. The apical and basal plasma membranes are extensively amplified through microvilli and infoldings; mitochondria are abundant and distributed unequally between the two types of cells (dark and light) composing the organ, more being present in the dark cells. The two cell types differ also in the type of microvilli projecting from their apical surface. In proecdysis these microvilli are replaced by much smaller ones which are associated with the deposition of the new cuticle.

Ultrastructural features of the gut of Sitophilus granarius (L.) (Coleoptera: Curculionidae) with notes on distribution of proteinases and amylases in crop and midgut

1984 ◽  
Vol 62 (7) ◽  
pp. 1251-1259 ◽  
Author(s):  
J. E. Baker ◽  
S. M. Woo ◽  
R. V. Byrd
Keyword(s):  
Plasma Membranes ◽  
Cell Types ◽  
Sitophilus Granarius ◽  
Posterior Midgut ◽  
Functional Differences ◽  
Basal Plasma ◽  
Dark Staining ◽  
Different Cell Types ◽  
Columnar Cells ◽  
Anterior Midgut

In addition to typical columnar cells, dark-staining cells characterized by deep invaginations of basal plasma membranes were found throughout the midgut of adult Sitophilus granarius (L.). These invaginations formed intracellular channels that extended to the perinuclear region and indicated an involvement of these cells in secretion and (or) absorption. Cells with large vacuolelike structures that occasionally filled the entire supranuclear region were found in the anterior midgut, while multicellular crypts and cells that formed apical extrusions into the lumen were common in the posterior midgut. Fine structure of gastric caeca indicated functional differences between those located in anterior and posterior midgut regions. Numerous dark-staining granules were found in apical regions of cells of the anterior caeca, whereas elongated mitochondria were found in microvilli that made up the brush border of posterior caecal cells. Thus, although the midgut is not obviously differentiated into zones, there are different cell types in different regions of the gut involved in digestive and nutrient absorption processes. Evidence indicated that amylase in S. granarius is secreted by salivary glands whereas trypsin and aminopeptidase are secreted by midgut. A slow, continuous secretion of amylase occurs whereas proteinases are secreted in response to ingested food.

Fine Structure of the Malpighian Tubules of the Mosquito, Culex pipiens

1971 ◽  
Vol 29 ◽  
pp. 402-403
Author(s):  
Brendan Clifford
Keyword(s):  
Fine Structure ◽  
Culex Pipiens ◽  
Stellate Cell ◽  
Malpighian Tubule ◽  
Cell Types ◽  
Instar Larva ◽  
Malpighian Tubules ◽  
Calliphora Erythrocephala ◽  
Distinct Cell ◽  
Basal Plasma

An ultrastructural investigation of the Malpighian tubules of the fourth instar larva of Culex pipiens was undertaken as part of a continuing study of the fine structure of transport epithelia.Each of the five Malpighian tubules was found to be morphologically identical and regionally undifferentiated. Two distinct cell types, the primary and stellate, were found intermingled along the length of each tubule. The ultrastructure of the stellate cell was previously described in the Malpighian tubule of the blowfly, Calliphora erythrocephala by Berridge and Oschman.The basal plasma membrane of the primary cell is extremely irregular, giving rise to a complex interconnecting network of basal channels. The compartments of cytoplasm entrapped within this system of basal infoldings contain mitochondria, free ribosomes, and small amounts of rough endoplasmic reticulum. The mitochondria are distinctive in that the cristae run parallel to the long axis of the organelle.

Membrane microdomains: lessons from microscopy

1995 ◽  
Vol 53 ◽  
pp. 776-777
Author(s):  
J.M. Robinson ◽  
J.M Oliver
Keyword(s):  
Spatial Distribution ◽  
Plasma Membrane ◽  
Epithelial Cells ◽  
Plasma Membranes ◽  
Cell Types ◽  
Imaging Modalities ◽  
Membrane Microdomains ◽  
Membrane Domains ◽  
Lateral Heterogeneity ◽  
Functional Importance

Specialized regions of plasma membranes displaying lateral heterogeneity are the focus of this Symposium. Specialized membrane domains are known for certain cell types such as differentiated epithelial cells where lateral heterogeneity in lipids and proteins exists between the apical and basolateral portions of the plasma membrane. Lateral heterogeneity and the presence of microdomains in membranes that are uniform in appearance have been more difficult to establish. Nonetheless a number of studies have provided evidence for membrane microdomains and indicated a functional importance for these structures.This symposium will focus on the use of various imaging modalities and related approaches to define membrane microdomains in a number of cell types. The importance of existing as well as emerging imaging technologies for use in the elucidation of membrane microdomains will be highlighted. The organization of membrane microdomains in terms of dimensions and spatial distribution is of considerable interest and will be addressed in this Symposium.

Intracellular traffic of the ecto-nucleotide pyrophosphatase/phosphodiesterase NPP3 to the apical plasma membrane of MDCK and Caco-2 cells: apical targeting occurs in the absence of N-glycosylation

2000 ◽  
Vol 113 (23) ◽  
pp. 4193-4202 ◽  
Author(s):  
N.R. Meerson ◽  
V. Bello ◽  
J.L. Delaunay ◽  
T.A. Slimane ◽  
D. Delautier ◽  
...  
Keyword(s):  
Cell Surface ◽  
Mdck Cells ◽  
Transmembrane Proteins ◽  
Cell Types ◽  
Apical Plasma Membrane ◽  
Apical Surface ◽  
Intracellular Traffic ◽  
Transmembrane Glycoprotein ◽  
Direct Demonstration ◽  
Targeting Signal

Glycosylation was considered the major signal candidate for apical targeting of transmembrane proteins in polarized epithelial cells. However, direct demonstration of the role of glycosylation has proved difficult because non-glycosylated apical transmembrane proteins usually do not reach the cell surface. Here we were able to follow the targeting of the apical transmembrane glycoprotein NPP3 both when glycosylated and non-glycosylated. Transfected in polarized MDCK and Caco-2 cells, NPP3 was exclusively expressed at the apical membrane. The transport kinetics of the protein to the cell surface were studied after metabolic (35)S-labeling and surface immunoprecipitation. The newly synthesized protein was mainly targeted directly to the apical surface in MDCK cells, whereas 50% transited through the basolateral surface in Caco-2 cells. In both cell types, the basolaterally targeted pool was effectively transcytosed to the apical surface. In the presence of tunicamycin, NPP3 was not N-glycosylated. The non-glycosylated protein was partially retained intracellularly but the fraction that reached the cell surface was nevertheless predominantly targeted apically. However, transcytosis of the non-glycosylated protein was partially impaired in MDCK cells. These results provide direct evidence that glycosylation cannot be considered an apical targeting signal for NPP3, although glycosylation is necessary for correct trafficking of the protein to the cell surface.

scholarly journals Photosensitization to ultraviolet irradiation and selective killing of cells following uptake of pyrene-containing fatty acid

1986 ◽  
Vol 85 (1) ◽  
pp. 149-159
Author(s):  
E. Fibach ◽  
O. Morand ◽  
S. Gatt
Keyword(s):  
Fatty Acid ◽  
Ultraviolet Irradiation ◽  
Plasma Membranes ◽  
Incubation Temperature ◽  
Serum Proteins ◽  
Neutral Lipids ◽  
Cell Types ◽  
Dodecanoic Acid ◽  
A Cell ◽  
The Individual

Cells were incubated with 12-(1-pyrene)-dodecanoic acid (P12), a long-chain fatty acid to which a pyrene ring has been attached covalently. This acid was transported across the plasma membranes of cells and subsequently incorporated into their neutral lipids and phospholipids. Irradiation of these pyrene-containing cells for short periods (0.5-4 min) with ultraviolet light at 366 nm resulted in eventual cell death. Similar irradiation had no effect on cells that had not been exposed to P12. The time of the period of irradiation necessary for inducing the toxic process was related to the quantity of P12 incorporated, the latter being a function of the respective metabolic activity of the individual cell type. The degree of incorporation of P12 into a cell, and consequently its acquired sensitivity to killing by ultraviolet irradiation at 366 nm, was affected by the incubation temperature and addition of non-fluorescent fatty acid, albumin or other serum proteins. Different degrees of incorporation of P12 into various cell types were used for selective killing and elimination of cell populations by irradiation at 366 nm. The combined procedure of preincubation with P12 followed by ultraviolet irradiation thus permitted selection of cell types with a greater resistance to this procedure.

scholarly journals Fluorescent, short-chain C6-NBD-sphingomyelin, but not C6-NBD-glucosylceramide, is subject to extensive degradation in the plasma membrane: implications for signal transduction related to cell differentiation

1995 ◽  
Vol 309 (3) ◽  
pp. 905-912 ◽  
Author(s):  
J W Kok ◽  
T Babia ◽  
K Klappe ◽  
D Hoekstra
Keyword(s):  
Signal Transduction ◽  
Plasma Membrane ◽  
Cell Differentiation ◽  
Plasma Membranes ◽  
Cell Types ◽  
Short Chain ◽  
Synthetic Activity ◽  
Intact Cells ◽  
Ht29 Cells ◽  
Extensive Degradation

The involvement of the plasma membrane in the metabolism of the sphingolipids sphingomyelin (SM) and glucosylceramide (GlcCer) was studied, employing fluorescent short-chain analogues of these lipids, 6-[N-(7-nitro-2,1,3-benzoxadiazol-4-yl) amino]hexanoylsphingosylphosphorylcholine (C6-NBD-SM), C6-NBD-GlcCer and their common biosynthetic precursor C6-NBD-ceramide (C6-NBD-Cer). Although these fluorescent short-chain analogues are metabolically active, some caution is to be taken in view of potential changes in biophysical/biochemical properties of the lipid compared with its natural counterpart. However, these short-chain analogues offer the advantage of studying the lipid metabolic enzymes in their natural environment, since detergent solubilization is not necessary for measuring their activity. These studies were carried out with several cell types, including two phenotypes (differing in state of differentiation) of HT29 cells. Degradation and biosynthesis of C6-NBD-SM and C6-NBD-GlcCer were determined in intact cells, in their isolated plasma membranes, and in plasma membranes isolated from rat liver tissue. C6-NBD-SM was found to be subject to extensive degradation in the plasma membrane, due to neutral sphingomyelinase (N-SMase) activity. The extent of C6-NBD-SM hydrolysis showed a general cell-type dependence and turned out to be dependent on the state of cell differentiation, as revealed for HT29 cells. In undifferentiated HT29 cells N-SMase activity was at least threefold higher than in its differentiated counterpart. In contrast, in all cell types studied, very little if any biosynthesis of C6-NBD-SM from the precursor C6-NBD-Cer occurred. Moreover, in the case of C6-NBD-GlcCer, neither hydrolytic nor synthetic activity was found to be associated with the plasma membrane. These results are discussed in the context of the involvement of the sphingolipids SM and GlcCer in signal transduction pathways in the plasma membrane.

scholarly journals INFOLDED BASAL PLASMA MEMBRANES FOUND IN EPITHELIA NOTED FOR THEIR WATER TRANSPORT

1956 ◽  
Vol 2 (4) ◽  
pp. 203-208 ◽  
Author(s):  
Daniel C. Pease
Keyword(s):  
Choroid Plexus ◽  
Water Transport ◽  
Ciliary Body ◽  
Plasma Membranes ◽  
Cell Layer ◽  
Submaxillary Gland ◽  
Basal Surface ◽  
Basal Plasma ◽  
Marked Tendency ◽  
Secretory Ducts

Epithelia noted for their water transport have been studied by electron microscopy with particular emphasis upon basal specializations. Epithelia of the submaxillary gland, choroid plexus, and ciliary body are described in this article, and compared with previous observations on the kidney. The basal surface of all these epithelia is tremendously expanded by folds which penetrate deeply into the cytoplasm. In the submaxillary gland this is particularly notable in cells of the serous alveoli and in the secretory ducts. In these instances the folds have a fairly regular distribution and have a marked tendency to turn back upon themselves and so form repeating S-shaped patterns. In the choroid plexus the penetrating basal folds are limited to the lateral regions of each ependymal cell where they blend with the intercellular membranes that are also folded. In the epithelium of the ciliary body it is the inner layer that is specialized. The surface adjacent to the cavity of the eye penetrates irregularly, nearly through the full depth of the cell layer. The exposed surface is, in a fundamental sense, the basal surface of this epithelial layer. It is apparent that the pattern of folding is quite distinctive in the different epithelia. Therefore, the specializations should be regarded as analogous rather than homologous. Topographic considerations presumably limit the manner in which basal cell surfaces might be expanded. Penetrating folds would seem to represent almost the only possible solution.

scholarly journals Surface membrane vesicles from mononuclear cells stimulate erythroid stem cells to proliferate in culture

Blood ◽  
1982 ◽  
Vol 60 (3) ◽  
pp. 583-594 ◽  
Author(s):  
N Dainiak ◽  
CM Cohen
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Mononuclear Cells ◽  
Surface Membrane ◽  
Freeze Fracture ◽  
Membrane Vesicles ◽  
Cell Types ◽  
Target Cells ◽  
Freeze Fracture Electron Microscopy

Abstract In order to examine the contribution of cell surface materials to erythroid burst-promoting activity (BPA), we separated media conditioned by a variety of human cell types into pellets and supernatants by centrifugation. When added to serum-restricted cultures of nonadherent human marrow cells, pellets contained about half of the total stimulatory activity. Freeze-fracture electron microscopy of the pellets revealed the presence of unilamellar membrane vesicles ranging from 0.10 to 0.40 microM in diameter. The amount of BPA in culture increased with added vesicle concentration in a saturable fashion. Preparation of leukocyte conditioned medium (LCM) from 125I-wheat germ agglutinin labeled cells and studies comparing the glycoprotein composition of vesicles with that of leukocyte plasma membranes suggest that LCM-derived vesicles are of plasma membrane origin. Moreover, partially purified leukocyte plasma membrane preparations also contained BPA. While disruption of vesicles by freezing/thawing and hypotonic lysis did not alter BPA, heat, trypsin, or pronase treatment removed greater than 65% of BPA, implying that vesicle surface rather than intravesicular molecules express BPA. Results of BPA assays performed in two-layer clots indicated that proximity to target cells is required for vesicle BPA expression. We conclude that membrane vesicles spontaneously shed from cell surfaces may be important regulators of erythroid burst proliferation in vitro.

scholarly journals Sustentacular Cell Enwrapment of Olfactory Receptor Neuronal Dendrites: An Update

Genes ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 493 ◽  
Author(s):  
Fengyi Liang
Keyword(s):  
Olfactory Receptor ◽  
Cell Types ◽  
Superficial Layer ◽  
Cell Junction ◽  
Common Belief ◽  
Apical Surface ◽  
Sustentacular Cell ◽  
Neuronal Dendrites ◽  
Sustentacular Cells ◽  
Receptor Neurons

The pseudostratified olfactory epithelium (OE) may histologically appear relatively simple, but the cytological relations among its cell types, especially those between olfactory receptor neurons (ORNs) and olfactory sustentacular cells (OSCs), prove more complex and variable than previously believed. Adding to the complexity is the short lifespan, persistent neurogenesis, and continuous rewiring of the ORNs. Contrary to the common belief that ORN dendrites are mostly positioned between OSCs, recent findings indicate a sustentacular cell enwrapped configuration for a majority of mature ORN dendrites at the superficial layer of the OE. After vertically sprouting out from the borderlines between OSCs, most of the immature ORN dendrites undergo a process of sideways migration and terminal maturation to become completely invaginated into and enwrapped by OSCs. Trailing the course of the dendritic sideways migration is the mesodendrite (mesentery of the enwrapped dendrite) made of closely apposed, cell junction connected plasma membrane layers of neighboring folds of the host sustentacular cell. Only a minority of the mature ORN dendrites at the OE apical surface are found at the borderlines between OSCs (unwrapped). Below I give a brief update on the cytoarchitectonic relations between the ORNs and OSCs of the OE. Emphasis is placed on the enwrapment of ORN dendrites by OSCs, on the sideways migration of immature ORN dendrites after emerging from the OE surface, and on the terminal maturation of the ORNs. Functional implications of ORN dendrite enwrapment and a comparison with myelination or Remak’s bundling of axons or axodendrites in the central and peripheral nervous system are also discussed.

scholarly journals Paralemmin, a Prenyl-Palmitoyl–anchored Phosphoprotein Abundant in Neurons and Implicated in Plasma Membrane Dynamics and Cell Process Formation

1998 ◽  
Vol 143 (3) ◽  
pp. 795-813 ◽  
Author(s):  
Christian Kutzleb ◽  
Gabriele Sanders ◽  
Raina Yamamoto ◽  
Xiaolu Wang ◽  
Beate Lichte ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Species Conservation ◽  
Cell Types ◽  
Membrane Dynamics ◽  
Morphological Properties ◽  
Developmentally Regulated ◽  
Membrane Flow ◽  
Western Blots ◽  
Process Formation

We report the identification and initial characterization of paralemmin, a putative new morphoregulatory protein associated with the plasma membrane. Paralemmin is highly expressed in the brain but also less abundantly in many other tissues and cell types. cDNAs from chicken, human, and mouse predict acidic proteins of 42 kD that display a pattern of sequence cassettes with high inter-species conservation separated by poorly conserved linker sequences. Prenylation and palmitoylation of a COOH-terminal cluster of three cysteine residues confers hydrophobicity and membrane association to paralemmin. Paralemmin is also phosphorylated, and its mRNA is differentially spliced in a tissue-specific and developmentally regulated manner. Differential splicing, lipidation, and phosphorylation contribute to electrophoretic heterogeneity that results in an array of multiple bands on Western blots, most notably in brain. Paralemmin is associated with the cytoplasmic face of the plasma membranes of postsynaptic specializations, axonal and dendritic processes and perikarya, and also appears to be associated with an intracellular vesicle pool. It does not line the neuronal plasmalemma continuously but in clusters and patches. Its molecular and morphological properties are reminiscent of GAP-43, CAP-23, and MARCKS, proteins implicated in plasma membrane dynamics. Overexpression in several cell lines shows that paralemmin concentrates at sites of plasma membrane activity such as filopodia and microspikes, and induces cell expansion and process formation. The lipidation motif is essential for this morphogenic activity. We propose a function for paralemmin in the control of cell shape, e.g., through an involvement in membrane flow or in membrane–cytoskeleton interaction.

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