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.

Differential centrifugation, calcium precipitation, and ultrasonic disruption of midgut cells of Erinnyis ello caterpillars. Purification of cell microvilli and inferences concerning secretory mechanisms

1986 ◽  
Vol 64 (2) ◽  
pp. 490-500 ◽  
Author(s):  
Custódio D. Santos ◽  
Alberto F. Ribeiro ◽  
Walter R. Terra
Keyword(s):  
Subcellular Fractions ◽  
Soluble Form ◽  
Differential Centrifugation ◽  
Posterior Midgut ◽  
Brush Borders ◽  
Columnar Cells ◽  
Differential Precipitation ◽  
Anterior Midgut ◽  
Erinnyis Ello ◽  
Calcium Precipitation

Subcellular fractions of the cells from the first and last third of midguts from Erinnyis ello caterpillars were obtained by conventional homogenization, followed by differential centrifugation or differential calcium precipitation, as well as by partial ultrasonic disruption. Aminopeptidase was enriched in the subcellular fractions, which in the electron microscope display mainly microvilli from the columnar cells (obtained by differential centrifugation and ultrasonic disruption), and also in the microvilli fraction obtained by differential precipitation. To account for the enzyme activities that sedimented with vesicles displaying brush borders, major amounts of the soluble glycosidases (cellobiase, N-acetylglucosaminidase, maltase, and trehalase) are assumed to be loosely bound to the cell glycocalyx, from where they are set free by homogenization and (or) freezing–thawing. Intracellular glycosidases seem to be bounded by membranes, which sediment together with vesicles that resemble secretory vesicles. The soluble form of amylase occurred mainly associated with the microvilli of anterior midgut cells and is supposed to be contained inside small vesicles, which are seen budding along columnar cell microvilli and fusing one with the other and with the tips of the microvilli from the anterior midgut cells. Secretory mechanisms are discussed in the light of the evidence that the posterior midgut secretes whereas the anterior midgut absorbs water.

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.

scholarly journals Synemin and vimentin are components of intermediate filaments in avian erythrocytes

1982 ◽  
Vol 92 (2) ◽  
pp. 299-312 ◽  
Author(s):  
BL Granger ◽  
EA Repasky ◽  
E Lazarides
Keyword(s):  
Plasma Membrane ◽  
Intermediate Filaments ◽  
Plasma Membranes ◽  
Cell Types ◽  
Special Role ◽  
Thin Sections ◽  
Avian Erythrocytes ◽  
Nonionic Detergent ◽  
Weight Protein ◽  
Different Cell Types

Synemin, a high-molecular-weight protein associated with intermediate filaments in muscle, and vimentin, an intermediate-filament subunit found in many different cell types, have been identified by immunologic and electrophoretic criteria as components of intermediate filaments in mature avian erythrocytes. Desmin, the predominant subunit of intermediate filaments in muscle, has not been detected in these cells. Two dimensional immunoautoradiography of proteolytic fragments of synemin and vimentin demonstates that the erythrocyte proteins are highly homologous, if not identical, to their muscle counterparts. Double immunoflurorescence reaveals that erythrocyte synemin and vimentin co-localize in a cytoplasmic network of sinuous filaments that extends from the nucleus to the plasma membrane and resists aggregation by colcemid. Erythrocytes that are attached to glass cover slips can be sonicated to remove nuclei and nonadherent regions of the plasma membrane; this leaves elliptical patches of adherent membrane that retain mats of vimentin- and synemin-containing intermediate filaments, as seen by immunofluorescence and rotary shadowing. Similarly, mechanical enucleation of erythrocyte ghosts in suspension allows isolation of plasma membranes that retain a significant fraction of the synemin and vimentin, as assayed by electrophoresis, and intermediate filaments, as seen in thin sections. Both synemin and vimentin remain insoluble along with spectrin and actin, in solutions containing nonionic detergent and high salt. However, brief exposure of isolated membrane to distilled water releases the synemin and vimentin together in nearly pure form, before the release of significant amounts of spectrin and actin. These data suggest that avian erythrocyte intermeditate filaments are somehow anchored to the plasma membrane; erythrocytes may thus provide a simple system for the study of intermediate filaments and their mode of interaction with membranes. In addition, these data, in conjunction with previous data from muscle, indicate that synemin is capable of associating with either desmin or vimentin and may thus perform a special role in the structure or function of intermediate filaments in erythrocytes as well as muscle.

scholarly journals Asymmetric wall ingrowth deposition in Arabidopsis phloem parenchyma transfer cells is tightly associated with sieve elements

2022 ◽  
Author(s):  
Xiaoyang Wei ◽  
Yuan Huang ◽  
David A Collings ◽  
David W McCurdy
Keyword(s):  
Cell Types ◽  
Phloem Loading ◽  
Transfer Cells ◽  
Companion Cell ◽  
Wall Ingrowths ◽  
Phloem Parenchyma ◽  
Wall Ingrowth ◽  
Functional Differences ◽  
Transgenic Lines ◽  
Different Cell Types

In Arabidopsis, polarized deposition of wall ingrowths in phloem parenchyma (PP) transfer cells (TCs) occurs adjacent to cells of the sieve element/companion cell (SE/CC) complex. However, the spatial relationships between these different cell types in minor veins, where phloem loading occurs, are poorly understood. PP TC development and wall ingrowth localization were compared to other phloem cells in leaves of Col-0 and the transgenic lines AtSUC2::AtSTP9-GFP and AtSWEET11::AtSWEET11-GFP that identify CCs and PP respectively. The development of PP TCs in minor veins, indicated by deposition of wall ingrowths, proceeded basipetally in leaves. However, not all PP develop ingrowths and higher levels of wall ingrowth deposition occur in abaxial- compared to adaxial-positioned PP TCs. Furthermore, the deposition of wall ingrowths was exclusively initiated on and preferentially covered the PP TC/SE interface, rather than the PP TC/CC interface, and only occurred in PP cells that were adjacent to SEs. Collectively, these results demonstrate the dominant impact of SEs on wall ingrowth deposition in PP TCs and suggest the existence of two sub-types of PP cells in leaf minor veins. Compared to PP cells, PP TCs showed more abundant accumulation of AtSWEET11-GFP, indicating functional differences in phloem loading between PP and PP TCs.

Antibody to H(+) V-ATPase subunit E colocalizes with portasomes in alkaline larval midgut of a freshwater mosquito (Aedes aegypti)

1999 ◽  
Vol 202 (18) ◽  
pp. 2449-2460 ◽  
Author(s):  
Z. Zhuang ◽  
P.J. Linser ◽  
W.R. Harvey
Keyword(s):  
Aedes Aegypti ◽  
Nutrient Uptake ◽  
Plasma Membranes ◽  
Molecular Mechanisms ◽  
Atpase Subunit ◽  
Larval Midgut ◽  
Posterior Midgut ◽  
Subunit E ◽  
Midgut Ph ◽  
Anterior Midgut

The pH profile, gross structure, ultrastructure and immunolabeling of the mosquito (Aedes aegypti) larval midgut are described as a first step in analyzing the role of plasma membrane H(+)V-ATPase in the alkalization of the gut, nutrient uptake and ionic regulation. Binding of an antibody to H(+)V-ATPase subunit E colocalizes with ‘portasomes’ (approximately 10 nm in diameter), which are thought to correspond to the V(1) part of the H(+) V-ATPase. In gastric caeca (pH 8), both antibody-binding sites and portasomes are located apically; in the anterior midgut (pH 10–11), they are located basally; and in the posterior midgut (pH approximately equal to 8) they are again located apically. The hypothesis that the energization of alkalization is mediated by an H(+) V-ATPase is supported by the inability of larvae to maintain the high pH after 72 h in 10 (micro)M bafilomycin B1. Confirming earlier reports, the two principal epithelial cell types are designated as ‘columnar’ and ‘cuboidal’ cells. The apical plasma membranes (microvilli) of epithelial cells in the gastric caeca and basal infoldings of anterior midgut are invaded by mitochondria that lie within approximately 20 nm of the portasome-studded plasma membranes. The colocalization of V-ATPase-immunolabeling sites and portasomes to specific plasma membranes within so-called ‘mitochondria-rich’ cells of gastric caeca and anterior midgut suggests that midgut alkalization in mosquitoes is achieved by molecular mechanisms similar to those that have been described in caterpillars, even though the gross structure of the midgut and the localization of the V-ATPase are dissimilar in the two species. In caterpillars, the high alkalinity is thought to break down dietary tannins, which block nutrient absorption; it may play a similar role in plant-detritus-feeding mosquito larvae. The colocalization of immunolabeling sites and portasomes, together with the presence of long, ‘absorptive-type’ microvilli in the posterior midgut, suggest that the V-ATPase energizes nutrient uptake there.

scholarly journals Aneuploidy in intestinal stem cells promotes gut dysplasia in Drosophila

2018 ◽  
Vol 217 (11) ◽  
pp. 3930-3946 ◽  
Author(s):  
Luís Pedro Resende ◽  
Augusta Monteiro ◽  
Rita Brás ◽  
Tatiana Lopes ◽  
Claudio E. Sunkel
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Spindle Assembly Checkpoint ◽  
Cell Types ◽  
Intestinal Stem Cells ◽  
Jnk Pathway ◽  
Posterior Midgut ◽  
Stem Cell Populations ◽  
Different Cell Types ◽  
Adult Drosophila

Aneuploidy is associated with different human diseases including cancer. However, different cell types appear to respond differently to aneuploidy, either by promoting tumorigenesis or causing cell death. We set out to study the behavior of adult Drosophila melanogaster intestinal stem cells (ISCs) after induction of chromosome missegregation either by abrogation of the spindle assembly checkpoint or through kinetochore disruption or centrosome amplification. These conditions induce moderate levels of aneuploidy in ISCs, and we find no evidence of apoptosis. Instead, we observe a significant accumulation of ISCs associated with increased stem cell proliferation and an excess of enteroendocrine cells. Moreover, aneuploidy causes up-regulation of the JNK pathway throughout the posterior midgut, and specific inhibition of JNK signaling in ISCs is sufficient to prevent dysplasia. Our findings highlight the importance of understanding the behavior of different stem cell populations to aneuploidy and how these can act as reservoirs for genomic alterations that can lead to tissue pathologies.

scholarly journals Microwave fixation improves antigenicity of glutaraldehyde-sensitive antigens while preserving ultrastructural detail.

1995 ◽  
Vol 43 (3) ◽  
pp. 307-311 ◽  
Author(s):  
M C Jamur ◽  
C D Faraco ◽  
L O Lunardi ◽  
R P Siraganian ◽  
C Oliver
Keyword(s):  
Bone Marrow ◽  
Mast Cells ◽  
Plasma Membranes ◽  
Cell Types ◽  
Cell Plasma ◽  
Morphological Detail ◽  
Strong Staining ◽  
Microwave Fixation ◽  
Different Cell Types ◽  
Rat Mast Cells

Microwave fixation for electron microscopy has been used primarily for post-embedding immunocytochemistry. The present study examined the ability of microwave fixation to preserve the antigenicity of glutaraldehyde-sensitive antigens for pre-embedding immunocytochemistry. Five monoclonal antibodies (MAbs) directed against cell surface components of rat mast cells were tested. The MAbs failed to show any labeling of conventionally fixed rat bone marrow-derived mast cells even at glutaraldehyde concentrations as low as 0.1%. Strong staining of mast cell plasma membranes was seen when bone marrow was initially fixed with 2% formaldehyde and then refixed in 2% glutaraldehyde/2% formaldehyde after immunostaining. However, the ultrastructural preservation of the cells was poor. Antigenicity and morphological detail were both preserved when bone marrow was fixed in 0.05% glutaraldehyde/2% formaldehyde for 4 sec in a 550-W microwave oven. With this method, mast cells in various stages of maturation as well as cells that did not contain granules were immunoreactive. This method should prove useful with antigens from many different cell types that are sensitive to glutaraldehyde fixation.

Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 118-119
Author(s):  
U. Aebi ◽  
P. Rew ◽  
T.-T. Sun
Keyword(s):  
Electron Microscopy ◽  
Structural Organization ◽  
Cell Types ◽  
Structural Features ◽  
Molecular Architecture ◽  
The Past ◽  
Keratin Filaments ◽  
Different Types ◽  
10 Nm Filaments ◽  
Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

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.

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