Changes in the plant endomembrane system associated with callose synthesis during the interaction between cowpea (Vigna unguiculata) and the cowpea rust fungus (Uromyces vignae)

1995 ◽  
Vol 73 (11) ◽  
pp. 1731-1738 ◽  
Author(s):  
Dubravka Škalamera ◽  
Michèle C. Heath
Keyword(s):  
Endoplasmic Reticulum ◽  
Vigna Unguiculata ◽  
De Novo ◽  
Rust Fungus ◽  
Leaf Tissue ◽  
Resistant Cultivar ◽  
Callose Deposition ◽  
Golgi Membranes ◽  
Rough Er ◽  
Uromyces Vignae

Electron microscopy and stereological analysis of cowpea (Vigna unguiculata) leaf tissue infected with the cowpea rust fungus (Uromyces vignae) revealed an increase in surface of plant endomembranes that was associated with callose synthesis or the presence of fungal haustoria. In the resistant cultivar in which the haustorium commonly becomes encased, an increase in surface of smooth membranes was observed in cytoplasmic regions adjacent to developing encasements compared with the regions away from the fungus or with any region in infected or uninfected callose nonsynthesizing cells. Cytoplasmic regions adjacent to the haustorium in callose nonsynthesizing cells had an increase in rough endoplasmic reticulum (ER). This increase was greater in a susceptible cultivar than in the resistant cultivar that was treated with tunicamycin to inhibit callose synthesis. In the latter situation, the lack of callose encasement allowed the haustorial neckband to form, but other ultrastructural signs of incompatibility remained, such as the presence of electron-opaque material associated with the extrahaustorial membrane. No differences between cultivars or treatments were observed in Golgi membranes. Our observations suggest that both callose synthesis and fungal presence are associated with de novo synthesis of membranes; callose deposition may require an increase in smooth membranes of uncertain origin, whereas the establishment of a haustorium may be dependent on increased synthesis of rough ER. Key words: callose, endoplasmic reticulum, resistance, stereology, tunicamycin.

scholarly journals Cowpea Mosaic Virus Infection Induces a Massive Proliferation of Endoplasmic Reticulum but Not Golgi Membranes and Is Dependent on De Novo Membrane Synthesis

2000 ◽  
Vol 74 (14) ◽  
pp. 6556-6563 ◽  
Author(s):  
Jan E. Carette ◽  
Marchel Stuiver ◽  
Jan Van Lent ◽  
Joan Wellink ◽  
Ab Van Kammen
Keyword(s):  
Endoplasmic Reticulum ◽  
Mosaic Virus ◽  
Fluorescent Protein ◽  
De Novo ◽  
Alfalfa Mosaic Virus ◽  
Lipid Synthesis ◽  
Cowpea Mosaic Virus ◽  
Living Plant ◽  
Fluorescence Confocal Microscopy ◽  
Golgi Membranes

ABSTRACT Replication of cowpea mosaic virus (CPMV) is associated with small membranous vesicles that are induced upon infection. The effect of CPMV replication on the morphology and distribution of the endomembrane system in living plant cells was studied by expressing green fluorescent protein (GFP) targeted to the endoplasmic reticulum (ER) and the Golgi membranes. CPMV infection was found to induce an extensive proliferation of the ER, whereas the distribution and morphology of the Golgi stacks remained unaffected. Immunolocalization experiments using fluorescence confocal microscopy showed that the proliferated ER membranes were closely associated with the electron-dense structures that contain the replicative proteins encoded by RNA1. Replication of CPMV was strongly inhibited by cerulenin, an inhibitor of de novo lipid synthesis, at concentrations where the replication of the two unrelated viruses alfalfa mosaic virus and tobacco mosaic virus was largely unaffected. These results suggest that proliferating ER membranes produce the membranous vesicles formed during CPMV infection and that this process requires continuous lipid biosynthesis.

In Vitro Induction of Crystals of MT Protein by Vinblastine-Colcemid in Mouse Spermatids

1974 ◽  
Vol 32 ◽  
pp. 132-133
Author(s):  
John J. Wolosewick ◽  
John H. D. Bryan
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Nuclear Ring ◽  
Rough Er ◽  
Distal Direction ◽  
In Vitro Induction

Early in spermiogenesis the manchette is rapidly assembled in a distal direction from the nuclear-ring-densities. The association of vesicles of smooth endoplasmic reticulum (SER) and the manchette microtubules (MTS) has been reported. In the mouse, osmophilic densities at the distal ends of the manchette are the organizing centers (MTOCS), and are associated with the SER. Rapid MT assembly and the lack of rough ER suggests that there is an existing pool of MT protein. Colcemid potentiates the reaction of vinblastine with tubulin and was used in this investigation to detect this protein.

Abstract 269: 5-aminoimidazole-4-carboxamide-3-ribonucleoside (AICAR) Decreases Soluble Fms-like Tyrosine Kinase-1 (sFlt-1) and Attenuates Endoplasmic Reticulum Stress in Rat Placental Villi Explants

Hypertension ◽  
2013 ◽  
Vol 62 (suppl_1) ◽  
Author(s):  
Christopher T Banek ◽  
Haley E Gillham ◽  
Sarah M Johnson ◽  
Hans C Dreyer ◽  
Jeffrey S Gilbert
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
De Novo ◽  
Vegf Receptor ◽  
Sprague Dawley ◽  
Hypoxic Conditions ◽  
Ampk Phosphorylation ◽  
Angiogenic Balance ◽  
Placental Villi ◽  
Placental Ischemia

Preeclampsia, defined by the onset of de novo hypertension and proteinuria near the 20th week of gestation, is a major contributor to maternal and fetal morbidity and mortality worldwide. Preeclampsia is often preceded by placental ischemia and an imbalance in circulating angiogenic factors (e.g. VEGF - vascular endothelial growth factor, sFlt-1 - soluble VEGF receptor 1). Recent studies also report increased expression of endoplasmic reticulum (ER) stress products in preeclamptic placentas. Our laboratory recently reported 5-aminoimidazole-4-carboxamide-3-ribonuceloside (AICAR) reduces blood pressure and improves angiogenic balance (increased VEGF, decreased sFlt-1) in rats with placental ischemia-induced hypertension, but the mechanism is unclear. We hypothesized AICAR would decrease sFlt-1, increase AMPK phosphorylation, and decrease ER stress in hypoxic placental villous explants. On day 19 of pregnancy, placentas were isolated from four Sprague-Dawley rats and immediately dissected in ice-cold phosphate-buffered saline. Explants were cultured for 12 hours in physiologic normoxic (8% O2) and hypoxic (1.5% O2) conditions. All experiments were performed in triplicate. VEGF secretion was unaffected by AICAR treatment in both normoxic and hypoxic conditions. AICAR decreased sFlt -1 secretion in hypoxic villi (2147±116 vs. *1411±67, P<0.05). Additionally, AMPK activation ratio was increased with AICAR, and was hypoxic-dependent (8%: 2.9±0.3; 8%+A: 3.3±0.1; 1.5%: 3.5±0.1; 1.5%+A: *4.5±0.01;*P<.05). Moreover, markers of ER stress were increased with hypoxia, and decreased with AICAR treatment (BiP 8%: 1.2±0.2; 8%+A: 1.0±0.0; 1.5%: *8.3±0.7; 1.5%+A: 1.9±0.0.3;*P<.05), (CHOP 8%: 0.5±0.0; 8%+A: 0.3±0.1; 1.5%: *1.7±0.1; 1.5%+A: 0.7±0.1;*P<.05). ATF4 was not changed with hypoxia or AICAR treatment. The present data show that AICAR stimulates AMPK phosphorylation and decreases ER stress response proteins in hypoxic placental villi. Further, the present data support the hypothesis that AICAR restores angiogenic balance by decreasing sFlt-1 rather than increasing VEGF secretion from placental villi. These findings suggest AICAR may improve placental function during pregnancies complicated by placental-ischemia.

scholarly journals De novo translation initiation on membrane-bound ribosomes as a mechanism for localization of cytosolic protein mRNAs to the endoplasmic reticulum

RNA ◽  
2014 ◽  
Vol 20 (10) ◽  
pp. 1489-1498 ◽  
Author(s):  
Sujatha Jagannathan ◽  
David W. Reid ◽  
Amanda H. Cox ◽  
Christopher V. Nicchitta
Keyword(s):  
Endoplasmic Reticulum ◽  
Translation Initiation ◽  
De Novo ◽  
Cytosolic Protein ◽  
Membrane Bound

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.

scholarly journals Retrograde trafficking of Argonaute 2 acts as a rate-limiting step for de novo miRNP formation on endoplasmic reticulum–attached polysomes in mammalian cells

2020 ◽  
Vol 3 (2) ◽  
pp. e201800161 ◽  
Author(s):  
Mainak Bose ◽  
Susanta Chatterjee ◽  
Yogaditya Chakrabarty ◽  
Bahnisikha Barman ◽  
Suvendra N Bhattacharyya
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
De Novo ◽  
Mirna Biogenesis ◽  
Argonaute 2 ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Cellular Context ◽  
Subcellular Compartmentalization ◽  
Rate Limiting

microRNAs are short regulatory RNAs in metazoan cells. Regulation of miRNA activity and abundance is evident in human cells where availability of target messages can influence miRNA biogenesis by augmenting the Dicer1-dependent processing of precursors to mature microRNAs. Requirement of subcellular compartmentalization of Ago2, the key component of miRNA repression machineries, for the controlled biogenesis of miRNPs is reported here. The process predominantly happens on the polysomes attached with the endoplasmic reticulum for which the subcellular Ago2 trafficking is found to be essential. Mitochondrial tethering of endoplasmic reticulum and its interaction with endosomes controls Ago2 availability. In cells with depolarized mitochondria, miRNA biogenesis gets impaired, which results in lowering of de novo–formed mature miRNA levels and accumulation of miRNA-free Ago2 on endosomes that fails to interact with Dicer1 and to traffic back to endoplasmic reticulum for de novo miRNA loading. Thus, mitochondria by sensing the cellular context regulates Ago2 trafficking at the subcellular level, which acts as a rate-limiting step in miRNA biogenesis process in mammalian cells.

scholarly journals Vesicular and uncoated Rab1-dependent cargo carriers facilitate ER to Golgi transport

2020 ◽  
Vol 133 (14) ◽  
pp. jcs239814 ◽  
Author(s):  
Laura M. Westrate ◽  
Melissa J. Hoyer ◽  
Michael J. Nash ◽  
Gia K. Voeltz
Keyword(s):  
Endoplasmic Reticulum ◽  
De Novo ◽  
Coated Vesicle ◽  
First Person ◽  
Coat Proteins ◽  
Animal Cells ◽  
Golgi Transport ◽  
Er Exit Sites ◽  
Copii Vesicles ◽  
Export System

ABSTRACTSecretory cargo is recognized, concentrated and trafficked from endoplasmic reticulum (ER) exit sites (ERES) to the Golgi. Cargo export from the ER begins when a series of highly conserved COPII coat proteins accumulate at the ER and regulate the formation of cargo-loaded COPII vesicles. In animal cells, capturing live de novo cargo trafficking past this point is challenging; it has been difficult to discriminate whether cargo is trafficked to the Golgi in a COPII-coated vesicle. Here, we describe a recently developed live-cell cargo export system that can be synchronously released from ERES to illustrate de novo trafficking in animal cells. We found that components of the COPII coat remain associated with the ERES while cargo is extruded into COPII-uncoated, non-ER associated, Rab1 (herein referring to Rab1a or Rab1b)-dependent carriers. Our data suggest that, in animal cells, COPII coat components remain stably associated with the ER at exit sites to generate a specialized compartment, but once cargo is sorted and organized, Rab1 labels these export carriers and facilitates efficient forward trafficking.This article has an associated First Person interview with the first author of the paper.

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