Différenciation de boutons floraux, de bourgeons végétatifs, de racines et de cal à partir de l'assise sous-épidermique des ramifications florales de Nicotiana tabacum Wisc. 38. Etude infrastructurale

1976 ◽  
Vol 54 (17) ◽  
pp. 1979-1996 ◽  
Author(s):  
M. Tran Thanh Van ◽  
A. Chlyah
Keyword(s):  
Endoplasmic Reticulum ◽  
Nicotiana Tabacum ◽  
Callus Formation ◽  
Starch Accumulation ◽  
Mitochondrial Activity ◽  
Cell Level ◽  
Flower Buds ◽  
Ultrastructural Studies ◽  
Different Types ◽  
General Activation

Ultrastructural studies of different types of differentiation, organogenetic (formation of flower buds, vegetative buds, or roots) or nonorganogenetic (callus formation), show important modifications at the subepidermal cell level. Besides the changes showing general activation leading to the first mitosis such as an increase of the ribosomes density, a more laboured endoplasmic reticulum, and a denser nucleus located near the centre, other changes seem to be related to a particular differentiation: for the flower program, an early starch accumulation and a higher mitochondrial activity in the cells take place and for the callus program important pinocytosis phenomena occur at the plasmalemma level.

scholarly journals FlsnRNA-seq: protoplasting-free full-length single-nucleus RNA profiling in plants

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Yanping Long ◽  
Zhijian Liu ◽  
Jinbu Jia ◽  
Weipeng Mo ◽  
Liang Fang ◽  
...  
Keyword(s):  
Single Cell ◽  
Cell Walls ◽  
Large Scale ◽  
Full Length ◽  
Cell Level ◽  
Root Cells ◽  
Rna Profiling ◽  
Different Types ◽  
Long Read ◽  
Single Nucleus

AbstractThe broad application of single-cell RNA profiling in plants has been hindered by the prerequisite of protoplasting that requires digesting the cell walls from different types of plant tissues. Here, we present a protoplasting-free approach, flsnRNA-seq, for large-scale full-length RNA profiling at a single-nucleus level in plants using isolated nuclei. Combined with 10x Genomics and Nanopore long-read sequencing, we validate the robustness of this approach in Arabidopsis root cells and the developing endosperm. Sequencing results demonstrate that it allows for uncovering alternative splicing and polyadenylation-related RNA isoform information at the single-cell level, which facilitates characterizing cell identities.

scholarly journals NRF2-mediated signaling is a master regulator of transcription factors in bovine granulosa cells under oxidative stress condition

2021 ◽  
Author(s):  
Mohamed Omar Taqi ◽  
Mohammed Saeed-Zidane ◽  
Samuel Gebremedhn ◽  
Dessie Salilew-Wondim ◽  
Ernst Tholen ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Proliferation ◽  
Endoplasmic Reticulum ◽  
Transcription Factors ◽  
Endoplasmic Reticulum Stress ◽  
Granulosa Cells ◽  
Mitochondrial Activity ◽  
Small Interference Rna ◽  
Nrf2 Signaling Pathway

AbstractTranscription factors (TFs) are known to be involved in regulating the expression of several classes of genes during folliculogenesis. However, the regulatory role of TFs during oxidative stress (OS) is not fully understood. The current study was aimed to investigate the regulation of the TFs in bovine granulosa cells (bGCs) during exposure to OS induced by H2O2 in vitro. For this, bGCs derived from ovarian follicles were cultured in vitro till their confluency and then treated with H2O2 for 40 min. Twenty-four hours later, cells were subjected to various phenotypic and gene expression analyses for genes related to TFs, endoplasmic reticulum stress, apoptosis, cell proliferation, and differentiation markers. The bGCs exhibited higher reactive oxygen species accumulation, DNA fragmentation, and endoplasmic reticulum stress accompanied by reduction of mitochondrial activity after exposure to OS. In addition, higher lipid accumulation and lower cell proliferation were noticed in H2O2-challenged cells. The mRNA level of TFs including NRF2, E2F1, KLF6, KLF9, FOS, SREBF1, SREBF2, and NOTCH1 was increased in H2O2-treated cells compared with non-treated controls. However, the expression level of KLF4 and its downstream gene, CCNB1, were downregulated in the H2O2-challenged group. Moreover, targeted inhibition of NRF2 using small interference RNA resulted in reduced expression of KLF9, FOS, SREBF2, and NOTCH1 genes, while the expression of KLF4 was upregulated. Taken together, bovine granulosa cells exposed to OS exhibited differential expression of various transcription factors, which are mediated by the NRF2 signaling pathway.

scholarly journals Septin-dependent compartmentalization of the endoplasmic reticulum during yeast polarized growth

2005 ◽  
Vol 169 (6) ◽  
pp. 897-908 ◽  
Author(s):  
Cosima Luedeke ◽  
Stéphanie Buvelot Frei ◽  
Ivo Sbalzarini ◽  
Heinz Schwarz ◽  
Anne Spang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Membrane Proteins ◽  
Diffusion Barriers ◽  
Yeast Cells ◽  
Dependent Manner ◽  
Protein Diffusion ◽  
Ultrastructural Studies ◽  
Bud Neck ◽  
Er Membrane

Polarized cells frequently use diffusion barriers to separate plasma membrane domains. It is unknown whether diffusion barriers also compartmentalize intracellular organelles. We used photobleaching techniques to characterize protein diffusion in the yeast endoplasmic reticulum (ER). Although a soluble protein diffused rapidly throughout the ER lumen, diffusion of ER membrane proteins was restricted at the bud neck. Ultrastructural studies and fluorescence microscopy revealed the presence of a ring of smooth ER at the bud neck. This ER domain and the restriction of diffusion for ER membrane proteins through the bud neck depended on septin function. The membrane-associated protein Bud6 localized to the bud neck in a septin-dependent manner and was required to restrict the diffusion of ER membrane proteins. Our results indicate that Bud6 acts downstream of septins to assemble a fence in the ER membrane at the bud neck. Thus, in polarized yeast cells, diffusion barriers compartmentalize the ER and the plasma membrane along parallel lines.

scholarly journals Ultrastructural studies of the hemocytes of Panstrongylus megistus (Hemiptera: Reduvidae)

1989 ◽  
Vol 84 (2) ◽  
pp. 171-188 ◽  
Author(s):  
Margherita A. Barracco ◽  
Clarice T. Loch
Keyword(s):  
Endoplasmic Reticulum ◽  
Light Microscopy ◽  
Rough Endoplasmic Reticulum ◽  
Lipid Droplets ◽  
Panstrongylus Megistus ◽  
Ultrastructural Studies ◽  
Hemocyte Count

Ultrastructural analyses revealed the presence of six hemocyte types in the hemolymph of Panstrogylus megistus, partially confirming our previous results obtained through light microscopy. Prohemocytes: small, round hemocytes with a thin cytoplasm layer, espcieally rich in free ribosomes and poor in membranous systems. Plasmatocytes: polymorphic cells, whose cytoplasm contains many lysosomes and a well developed rough endoplasmic reticulum (RER).They are extremely phagocytic. Sometimes, they show a large vacuolation. Granulocytes: granular hemocytes whose granules show different degrees of electrondensity. Most of them, have an internal structuration. Coagulocytes: oval or elongated hemocytes, which show pronounced perinuclear cisternae as normally observed in coagulocytes. The cytoplasm is usually electrondense, poor in membranous systems and contains many labile granules. Oenocytoids: large and very stable hemocytes, whose homogeneous cytoplasme is rich in loose ribosomes and poor in membranous systems. Adipohemocytes: large cells, containing several characteristic lipid droplets. The cytoplasm is also rich in glycogen, RER and large mitochondria. The total and differential hemocyte count (THC and DHC) were also calculated for this reduviid. THC increases from 2,900 hemocytes/cubic millimeter of hemolymph in the 4th intar to 4,350 in the 5th and then, decreases to 1,950 in the adults. Plasmatocytes and coagulocytes are the predominant hemocyte types.

scholarly journals Simultaneous Exposure of Different Nanoparticles Influences Cell Uptake

Pharmaceutics ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 136
Author(s):  
Isa de Boer ◽  
Ceri J. Richards ◽  
Christoffer Åberg
Keyword(s):  
Drug Delivery ◽  
Individual Cell ◽  
Model System ◽  
Cell Uptake ◽  
Target Cells ◽  
Cell Level ◽  
Polystyrene Nanoparticles ◽  
Simultaneous Exposure ◽  
Different Types ◽  
Uptake Studies

Drug delivery using nano-sized carriers holds tremendous potential for curing a range of diseases. The internalisation of nanoparticles by cells, however, remains poorly understood, restricting the possibility for optimising entrance into target cells, avoiding off-target cells and evading clearance. The majority of nanoparticle cell uptake studies have been performed in the presence of only the particle of interest; here, we instead report measurements of uptake when the cells are exposed to two different types of nanoparticles at the same time. We used carboxylated polystyrene nanoparticles of two different sizes as a model system and exposed them to HeLa cells in the presence of a biomolecular corona. Using flow cytometry, we quantify the uptake at both average and individual cell level. Consistent with previous literature, we show that uptake of the larger particles is impeded in the presence of competing smaller particles and, conversely, that uptake of the smaller particles is promoted by competing larger particles. While the mechanism(s) underlying these observations remain(s) undetermined, we are partly able to restrain the likely possibilities. In the future, these effects could conceivably be used to enhance uptake of nano-sized particles used for drug delivery, by administering two different types of particles at the same time.

scholarly journals Mitochondrial–Endoplasmic Reticulum Interplay: A Lifelong On–Off Relationship?

Contact ◽  
2019 ◽  
Vol 2 ◽  
pp. 251525641986122 ◽  
Author(s):  
Corina T. Madreiter-Sokolowski ◽  
Roland M. Malli ◽  
Wolfgang F. Graier
Keyword(s):  
Endoplasmic Reticulum ◽  
Adenosine Triphosphate ◽  
Therapeutic Strategies ◽  
Mitochondrial Activity ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Potential Target ◽  
Pathological Conditions ◽  
Elevated Glucose ◽  
Stimulation Of

This article comments recent publications that highlight an intriguing importance of specific settings in the interaction between the mitochondria and the endoplasmic reticulum to ensure cell-specific functions like the responsiveness to elevated glucose in pancreatic β-cells. Hence, alterations of the mitochondria–endoplasmic reticulum communications under various pathological conditions like aging or cancer often come with enhanced Ca2+ transfer that, in turn, yields stimulation of basal mitochondrial activity to meet the increasing adenosine triphosphate demand of the very cell. Such observations identify mitochondria-associated membranes as potential target for new therapeutic strategies against aging or cancer.

scholarly journals Phosphoglucoisomerase Is an Important Regulatory Enzyme in Partitioning Carbon out of the Calvin-Benson Cycle

2020 ◽  
Vol 11 ◽  
Author(s):  
Alyssa L. Preiser ◽  
Aparajita Banerjee ◽  
Sean E. Weise ◽  
Luciana Renna ◽  
Federica Brandizzi ◽  
...  
Keyword(s):  
Nicotiana Tabacum ◽  
Starch Accumulation ◽  
Plant Leaves ◽  
Recombinant Enzymes ◽  
Sucrose Biosynthesis ◽  
Isolated Chloroplasts

Phosphoglucoisomerase (PGI) isomerizes fructose 6-phosphate (F6P) and glucose 6-phosphate (G6P) in starch and sucrose biosynthesis. Both plastidic and cytosolic isoforms are found in plant leaves. Using recombinant enzymes and isolated chloroplasts, we have characterized the plastidic and cytosolic isoforms of PGI. We have found that the Arabidopsis plastidic PGI Km for G6P is three-fold greater compared to that for F6P and that erythrose 4-phosphate is a key regulator of PGI activity. Additionally, the Km of spinach plastidic PGI can be dynamically regulated in the dark compared to the light and increases by 200% in the dark. We also found that targeting Arabidopsis cytosolic PGI into plastids of Nicotiana tabacum disrupts starch accumulation and degradation. Our results, in combination with the observation that plastidic PGI is not in equilibrium, indicates that PGI is an important regulatory enzyme that restricts flow and acts as a one-way valve preventing backflow of G6P into the Calvin-Benson cycle. We propose the PGI may be manipulated to improve flow of carbon to desired targets of biotechnology.

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