scholarly journals Early Stages of Golgi Vesicle and Tubule Formation Require Diacylglycerol

2009 ◽  
Vol 20 (3) ◽  
pp. 780-790 ◽  
Author(s):  
Lennart Asp ◽  
Fredrik Kartberg ◽  
Julia Fernandez-Rodriguez ◽  
Maria Smedh ◽  
Markus Elsner ◽  
...  
Keyword(s):  
Rna Interference ◽  
Golgi Apparatus ◽  
Phosphatidic Acid ◽  
Golgi Vesicle ◽  
Tubule Formation ◽  
Bud Formation ◽  
Early Stages ◽  
Golgi Membranes ◽  
Phosphatidate Phosphohydrolase ◽  
Late Stages

We have investigated the role for diacylglycerol (DAG) in membrane bud formation in the Golgi apparatus. Addition of propranolol to specifically inhibit phosphatidate phosphohydrolase (PAP), an enzyme responsible for converting phosphatidic acid into DAG, effectively prevents formation of membrane buds. The effect of PAP inhibition on Golgi membranes is rapid and occurs within 3 min. Removal of the PAP inhibitor then results in a rapid burst of buds, vesicles, and tubules that peaks within 2 min. The inability to form buds in the presence of propranolol does not appear to be correlated with a loss of ARFGAP1 from Golgi membranes, as knockdown of ARFGAP1 by RNA interference has little or no effect on actual bud formation. Rather, knockdown of ARFGAP1 results in an increase in membrane buds and a decrease of vesicles and tubules suggesting it functions in the late stages of scission. How DAG promotes bud formation is discussed.

Requirement of the Auxin Polar Transport System in Early Stages of Arabidopsis Floral Bud Formation

1991 ◽  
Vol 3 (7) ◽  
pp. 677 ◽  
Author(s):  
Kiyotaka Okada ◽  
Junichi Ueda ◽  
Masako K. Komaki ◽  
Callum J. Bell ◽  
Yoshiro Shimura
Keyword(s):  
Transport System ◽  
Polar Transport ◽  
Bud Formation ◽  
Early Stages ◽  
Auxin Polar Transport ◽  
Floral Bud

scholarly journals The pattern of appearance of enzymic activity during the development of the Golgi apparatus in amoebae

1978 ◽  
Vol 34 (1) ◽  
pp. 53-63
Author(s):  
C.J. Flickinger
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Rough Endoplasmic Reticulum ◽  
Enzymic Activity ◽  
Nuclear Transplantation ◽  
Similar Distribution ◽  
Cytochemical Staining ◽  
Light Reaction ◽  
Golgi Bodies ◽  
Golgi Membranes

The appearance of enzymic activity during the development of the Golgi apparatus was studied by cytochemical staining of renucleated amoebae. In cells enucleated for 4 days, there was a great decline in size and number of Golgi bodies, or dictyosomes. Subsequent renucleation by nuclear transplantation resulted in a regeneration of Golgi bodies. Samples of amoebae were fixed and incubated for cytochemical staining at intervals of 1, 6, or 24 h after renucleation. Enzymes selected for study were guanosine diphosphatase (GDPase), esterase, and thiamine pyrophosphatase (TPPase). All three were found in the Golgi apparatus of normal amoebae but they differed in their overall intracellular distribution. GDPase was normally present at the convex pole of the Golgi apparatus, in rough endoplasmic reticulum, and in the nuclear envelope. In amoebae renucleated for 1 h, light reaction product for GDPase was present throughout the small stacks of cisternae that represented the forming Golgi apparatus. By 6 h following the operation GDPase reaction product was concentrated at the convex pole of the Golgi apparatus. Esterase, which was distributed throughout the stacks of normal Golgi cisternae, displayed a similar distribution in the forming Golgi bodies as soon as they were visible. TPPase was normally present in the Golgi apparatus but was not found in the endoplasmic reticulum. In contrast to the other enzymes, TPPase reaction product was absent from the forming Golgi apparatus 1 and 6 h after renucleation, and did not appear in the Golgi apparatus until 24 h after operation. Thus, enzymes held in common between the rough endoplasmic reticulum and the Golgi apparatus were present in the forming Golgi apparatus as soon as it was detectable, but an enzyme cytochemically localized to the Golgi apparatus only appeared later in development of the organelle. It is suggested that Golgi membranes might be derived from the endoplasmic reticulum and thus immediately contain endoplasmic reticulum enzymes, while Golgi-specific enzymes are added later in development.

IFITM proteins that restrict the early stages of respiratory virus infection do not influence late-stage replication

2021 ◽  
Author(s):  
Tina Meischel ◽  
Svenja Fritzlar ◽  
Fernando Villalon-Letelier ◽  
Melkamu B. Tessema ◽  
Andrew G. Brooks ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Antiviral Activity ◽  
Influenza A ◽  
Respiratory Viruses ◽  
Parainfluenza Virus ◽  
Early Stages ◽  
Infected Cells ◽  
Cellular Entry ◽  
Overexpression System ◽  
Late Stages

Interferon-induced transmembrane (IFITM) proteins inhibit a broad range of enveloped viruses by blocking entry into host cells. We used an inducible overexpression system to investigate if IFITM1, IFITM2 and IFITM3 could modulate early and/or late stages of influenza A virus (IAV) or parainfluenza virus (PIV)-3 infection in human A549 airway epithelial cells. IAV and PIV-3 represent respiratory viruses which utilise distinct cellular entry pathways. We verify entry by endocytosis for IAV, whereas PIV-3 infection was consistent with fusion at the plasma membrane. Following induction prior to infection, all three IFITM proteins restricted the percentage of IAV-infected cells at 8 hours post-infection. In contrast, prior induction of IFITM1 and IFITM2 did not inhibit PIV-3 infection, although a modest reduction was observed with IFITM3. siRNA-mediated knockdown of endogenous IFITM1, IFITM2 and IFITM3 expression, in the presence or absence of pre-treatment with type I interferon, resulted in increased IAV, but not PIV-3, infection. This suggests that while all three IFITMs display antiviral activity against IAV, they do not restrict the early stages of PIV-3 infection. IAV and PIV-3 infection culminates in viral egress through budding at the plasma membrane. Inducible expression of IFITM1, IFITM2 or IFITM3 immediately after infection did not impact titres of infectious virus released from IAV or PIV-3 infected cells. Our findings show that IFITM proteins differentially restrict the early stages of infection of two respiratory viruses with distinct cellular entry pathways, but do not influence the late stages of replication for either virus. IMPORTANCE Interferon-induced transmembrane (IFITM) proteins restrict the initial stages of infection for several respiratory viruses, however their potential to modulate the later stages of virus replication has not been explored. In this study we highlight the utility of an inducible overexpression system to assess the impact of IFITM proteins on either early or late stage replication of two respiratory viruses. We demonstrate antiviral activity by IFITM1, IFITM2 and IFITM3 against influenza A virus (IAV) but not parainfluenza virus (PIV)-3 during the early stages of cellular infection. Furthermore, IFITM induction following IAV or PIV-3 infection does not restrict the late stages of replication of either virus. Our findings show that IFITM proteins can differentially restrict the early stages of infection of two viruses with distinct cellular entry pathways, yet do not influence the late stages of replication for either virus.

Growth and Differentiation of Transplanted W/Wv Marrow

Blood ◽  
1967 ◽  
Vol 30 (5) ◽  
pp. 601-616 ◽  
Author(s):  
JERRY P. LEWIS ◽  
LOIS F. O’GRADY ◽  
SELDON E. BERNSTEIN ◽  
ELIZABETH S. RUSSELL ◽  
FRANK E. TROBAUGH
Keyword(s):  
Macrocytic Anemia ◽  
Severe Anemia ◽  
Early Stages ◽  
Erythroid Precursors ◽  
Erythroid Maturation ◽  
Reduced Rate ◽  
Immature Cells ◽  
Erythroid Development ◽  
Mutant Genes ◽  
Late Stages

Abstract This paper reports new data on the effect of the action of the mutant genes W and Wv on murine hemopoiesis. Our studies demonstrate that the presence of these mutant genes produces: (1) a macrocytic anemia with neither granulocytopenia nor thrombocytopenia; (2) a severe defect in the early stages of hemopoietic repopulation manifested by (a) an apparent block in the differentiation of immature cells into erythroid precursors, and (b) a greatly reduced rate of proliferation of differentiated hemopoietic elements. These data demonstrate the existence of genetic influence on repopulation and differentiation of transplanted marrow and suggest that severe anemia may result not only from defects in the late stages of erythroid development but also from abnormalities in the early stages of erythroid maturation and hemopoietic repopulation.

scholarly journals NEPHRITIS AND ITS INFLUENCE UPON HEMOGLOBIN PRODUCTION IN EXPERIMENTAL ANEMIA

1939 ◽  
Vol 69 (4) ◽  
pp. 485-498 ◽  
Author(s):  
G. H. Whipple ◽  
F. S. Robscheit-Robbins
Keyword(s):  
Early Stages ◽  
Late Stages ◽  
Hemoglobin Production

Spontaneous glomerulonephritis develops not infrequently (11 per cent incidence) in the anemia colony. The course of the nephritis is insidious and usually extends over several years but ends in uremia, often with terminal bronchopneumonia. Hemoglobin production in these standard anemic dogs is well established as related to various standard food factors. These tests are summarized in the tables above to show the changes that appear year by year in the life of each dog. Nephritis causes little or no change in hemoglobin production in anemic dogs in the early stages of the disease. In the late stages of nephritis there may be no change or moderate changes in hemoglobin production in these anemic dogs. The average is 70 per cent of normal hemoglobin production in advanced nephritis. It seems unlikely that this degree of impairment of hemoglobin production in nephritis would result in spontaneous anemia in the dog.

scholarly journals Three-dimensional analysis of synaptic organization in the hippocampal CA1 field in Alzheimer’s disease

Brain ◽  
2020 ◽  
Author(s):  
Marta Montero-Crespo ◽  
Marta Domínguez-Álvaro ◽  
Lidia Alonso-Nanclares ◽  
Javier DeFelipe ◽  
Lidia Blazquez-Llorca
Keyword(s):  
Electron Microscopy ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Β ◽  
Cortical Atrophy ◽  
Structural Basis ◽  
Synaptic Organization ◽  
Synaptic Density ◽  
Early Stages ◽  
Late Stages

Abstract Alzheimer’s disease is the most common form of dementia, characterized by a persistent and progressive impairment of cognitive functions. Alzheimer’s disease is typically associated with extracellular deposits of amyloid-β peptide and accumulation of abnormally phosphorylated tau protein inside neurons (amyloid-β and neurofibrillary pathologies). It has been proposed that these pathologies cause neuronal degeneration and synaptic alterations, which are thought to constitute the major neurobiological basis of cognitive dysfunction in Alzheimer’s disease. The hippocampal formation is especially vulnerable in the early stages of Alzheimer’s disease. However, the vast majority of electron microscopy studies have been performed in animal models. In the present study, we performed an extensive 3D study of the neuropil to investigate the synaptic organization in the stratum pyramidale and radiatum in the CA1 field of Alzheimer’s disease cases with different stages of the disease, using focused ion beam/scanning electron microscopy (FIB/SEM). In cases with early stages of Alzheimer’s disease, the synapse morphology looks normal and we observed no significant differences between control and Alzheimer’s disease cases regarding the synaptic density, the ratio of excitatory and inhibitory synapses, or the spatial distribution of synapses. However, differences in the distribution of postsynaptic targets and synaptic shapes were found. Furthermore, a lower proportion of larger excitatory synapses in both strata were found in Alzheimer’s disease cases. Individuals in late stages of the disease suffered the most severe synaptic alterations, including a decrease in synaptic density and morphological alterations of the remaining synapses. Since Alzheimer’s disease cases show cortical atrophy, our data indicate a reduction in the total number (but not the density) of synapses at early stages of the disease, with this reduction being much more accentuated in subjects with late stages of Alzheimer’s disease. The observed synaptic alterations may represent a structural basis for the progressive learning and memory dysfunctions seen in Alzheimer’s disease cases.

Larval morphology of Dart-Poison Frogs (Anura: Dendrobatoidea: Aromobatidae and Dendrobatidae)

Zootaxa ◽  
2013 ◽  
Vol 3637 (5) ◽  
pp. 569 ◽  
Author(s):  
DAVID A. SÁNCHEZ
Keyword(s):  
Digestive System ◽  
Larval Morphology ◽  
Stages Of Development ◽  
Taxonomic Assignment ◽  
Digestive Tube ◽  
Early Stages ◽  
Constant Diameter ◽  
The Family ◽  
Upper Jaw ◽  
Late Stages

Tadpoles in the superfamily Dendrobatoidea (families Aromobatidae and Dendrobatidae), housed in zoological collections or illustrated in publications, were studied. For the most part, tadpoles of species within the family Aromobatidae, the subfamilies Colostethinae and Hyloxalinae (of the family Dendrobatidae), and those of the genus Phyllobates, Dendrobatinae (Dendrobatidae) have slender anterior jaw sheaths with a medial notch and slender lateral processes, triangular fleshy projections on the inner margin of the nostrils and digestive tube with constant diameter and color and its axis sinistrally directed, concealing the liver and other organs. These morphologies are different from the ones observed in tadpoles of species included in the Dendrobatinae (minus Phyllobates). Exceptions to these morphological arrangements are noted, being the digestive system arrangement and the nostril ornamentation more plastic than the shape of the upper jaw sheath. Tadpoles of all species of the Dendrobatoidea have similar disposition of digestive organs in early stages, but differentiate in late stages of development. Classifying the upper jaw sheath into the two recognized states is possible from very early stages of development, but gut disposition and nostril ornamentation cannot be determined until late in development, making classification and taxonomic assignment of tadpoles based on these morphological features challenging.

Increased phosphatidic acid and decreased lysophosphatidic acid in response to thrombin is associated with inhibition of platelet aggregation

1993 ◽  
Vol 71 (9-10) ◽  
pp. 432-439 ◽  
Author(s):  
Jon M. Gerrard ◽  
Pauline Robinson ◽  
Michael Narvey ◽  
Archibald McNicol
Keyword(s):  
Platelet Aggregation ◽  
Phosphatidic Acid ◽  
Lysophosphatidic Acid ◽  
Human Platelet ◽  
Inhibitory Effect ◽  
Phospholipase A ◽  
Direct Role ◽  
Inhibition Of Platelet Aggregation ◽  
Phosphatidate Phosphohydrolase ◽  
Rule Out

Thromboxane A2, produced from the arachidonic acid released from platelet phospholipids by phospholipase A2, stimulates platelet aggregation. It remains unresolved whether additional products of platelet phospholipase A2 might promote aggregation. To address this question, we have used aspirin-treated platelets to block thromboxane A2 formation and studied the influence of the phospholipase A2 inhibitor U10029A on platelet aggregation and secretion in response to thrombin. U10029A at 100 μM markedly inhibited platelet aggregation, but had no effect on platelet secretion. Since this concentration of U10029A effectively blocked lysophosphatidic acid (LPA) formation, LPA was added and found to substantially reverse the inhibitory effect of U10029A in these platelets. Furthermore, the action of U10029A was not due to inhibition of phosphatidate phosphohydrolase because U10029A, unlike propranolol, did not inhibit this enzyme. Although it is not possible to conclusively rule out an effect of U10029A in addition to its inhibition of phospholipase A2, our results reveal that a product of phospholipase A2 other than thromboxane A2 is important for platelet aggregation, but not for secretion in response to thrombin. Our data suggest that this product is LPA. Since the amount of phosphatidic acid (PA) increased dramatically concurrent with inhibition of platelet aggregation, it is safe to conclude that PA has no direct role to promote platelet aggregation in response to thrombin.Key words: lysophosphatidic acid, phosphatidic acid, phospholipase A2, human platelet.

scholarly journals CYTOLOGICAL STUDIES ON TWO FUNCTIONAL HEPATOMAS

1962 ◽  
Vol 15 (2) ◽  
pp. 289-312 ◽  
Author(s):  
Edward Essner ◽  
Alex B. Novikoff
Keyword(s):  
Endoplasmic Reticulum ◽  
Acid Phosphatase ◽  
Golgi Apparatus ◽  
Phosphatase Activity ◽  
Acid Phosphatase Activity ◽  
Secretory Granules ◽  
Dynamic State ◽  
Secretory Product ◽  
Electron Microscopic ◽  
Golgi Membranes

The Reuber hepatoma H-35 and Morris hepatoma 5123 have been studied by electron microscopy and by cytochemical staining methods for a number of phosphatases. These studies emphasize the resemblances of the two tumors to rat liver, but they also indicate distinctive features in each of the three tissues. Secretory product accumulates within the cisternae of the Golgi apparatus that dilate to form the Golgi vacuoles. The vacuoles apparently separate, and secretory material undergoes further condensation within them. These "secretory vacuoles" possess acid phosphatase activity and may thus be considered lysosomes. The membranes of the Golgi apparatus are without acid phosphatase activity but show high levels of thiaminepyrophosphatase activity. The endoplasmic reticulum also hydrolyzes thiaminepyrophosphate but at a lower rate; it hydrolyzes the diphosphates of uridine, guanosine, and inosine rapidly. These observations and the electron microscopic images are consistent with the view that the cytomembranes are in a dynamic state of flux, movement, and transformation in the living cell, and that smooth surfaced derivatives of the endoplasmic reticulum become refashioned into the Golgi membranes as the Golgi membranes are being refashioned into those that delimit secretory vacuoles. The variations encountered in the two hepatomas are described. The electron microscope literature dealing with the relations of the Golgi apparatus to secretory granules, on the one hand, and the endoplasmic reticulum, on the other, is reviewed briefly.

The effect of novel small molecule drugs in human explants across the disease sequence in colorectal cancer.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. e13570-e13570
Author(s):  
Adrian Gerard Murphy ◽  
Rory Casey ◽  
David William Fennelly ◽  
Alison Reynolds ◽  
Miriam Tosetto ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Ex Vivo ◽  
Survival Rates ◽  
Colorectal Tumor ◽  
Preclinical Development ◽  
Zebrafish Larvae ◽  
Early Stages ◽  
Late Stages ◽  
Human Explants ◽  
Tnf Secretion

e13570 Background: The treatment of metastatic colorectal cancer has been improved by combining cytotoxic chemotherapy with bevacizumab. Newer anti-angiogenic agents are required to improve survival rates as response rates with the current therapies are modest. The preclinical development of such drugs is time-consuming and new methods are required to test the efficacy of lead drugs which represent the entire tumor micro-environment. Methods: Chemical screens were performed in zebrafish larvae to identify hits that affected intersegmental angiogenesis. Five lead drugs were then tested for cytotoxicity using the crystal violet assay. These drugs were tested using ex vivo colorectal tumor explants to determine their effect on secretion of IL-1β, TNF, IL-6 and VEGF. Human explants from 20 patients (Dukes A-D) were cultured for 72 hours and the levels of the above factors measured by ELISA. Comparisons were made between early (Dukes A&B) and late stages (Dukes C&D). Results: One thousand drugs were screened and 5 were found to reduce intersegmental angiogenesis in zebrafish larvae: AM1, AM2, AM3, AM4 and AM5. The drugs did not affect cell growth levels at 10 µM concentration. From the explant studies: AM1 decreased secretion of VEGF in late stages (p=0.005) and IL-6 in early stages (p=0.009). AM2 decreased VEGF in early (p=0.004) and late stages (p=0.02). AM3 decreased TNF secretion in late stages (p=0.02) and IL-6 secretion in early (p=0.009) and late stages (p<0.0001). AM4 decreased VEGF secretion in early stages (p=0.001), IL-6 in early stages (p<0.001) and late stages (p=0.03) and IL-1β in early stages (p=0.002). AM5 decreased IL-6 secretion in the early stages (p=0.03) and IL-1β in the early stages (p=0.001).Overall, IL-1β secretion was reduced by AM4, AM3 and AM5 (p<0.05). IL-6 secretion was reduced by AM1, AM3 and AM4 (p=0.001). TNF secretion was reduced by AM3 (p=0.02) and VEGF secretion was reduced by AM1, AM2 and AM4 (p<0.005). Conclusions: These studies show these drugs have stage-specific effects in colorectal tumor explants and may have the potential as new anti-angiogenic agents in colorectal cancer.

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