scholarly journals Calreticulin expression and localization in relation to exchangeable Ca2+ during pollen development in Petunia

2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Anna Suwińska ◽  
Piotr Wasąg ◽  
Elżbieta Bednarska-Kozakiewicz ◽  
Marta Lenartowska ◽  
Robert Lenartowski
Keyword(s):  
Pollen Development ◽  
Intracellular Transport ◽  
High Rate ◽  
Eukaryotic Cells ◽  
Northern Hybridization ◽  
Local Concentration ◽  
Cellular Interactions ◽  
Exchangeable Ca ◽  
Tapetal Cells ◽  
Intracellular Ca

Abstract Background Pollen development in the anther in angiosperms depends on complicated cellular interactions associated with the expression of gametophytic and sporophytic genes which control fundamental processes during microsporo/gametogenesis, such as exo/endocytosis, intracellular transport, cell signaling, chromatin remodeling, and cell division. Most if not all of these cellular processes depend of local concentration of calcium ions (Ca2+). Work from our laboratory and others provide evidence that calreticulin (CRT), a prominent Ca2+-binding/buffering protein in the endoplasmic reticulum (ER) of eukaryotic cells, may be involved in pollen formation and function. Here, we show for the first time the expression pattern of the PhCRT1 gene and CRT accumulation in relation to exchangeable Ca2+ in Petunia hybrida developing anther, and discuss probable roles for this protein in the male gametophyte development. Results Using northern hybridization, western blot analysis, fluorescent in situ hybridization (FISH), immunocytochemistry, and potassium antimonate precipitation, we report that PhCRT1 is highly expressed in the anther and localization pattern of the CRT protein correlates with loosely bound (exchangeable) Ca2+ during the successive stages of microsporo/gametogenesis. We confirmed a permanent presence of both CRT and exchangeable Ca2+ in the germ line and tapetal cells, where these factors preferentially localized to the ER which is known to be the most effective intracellular Ca2+ store in eukaryotic cells. In addition, our immunoblots revealed a gradual increase in CRT level from the microsporocyte stage through the meiosis and the highest CRT level at the microspore stage, when both microspores and tapetal cells show extremely high secretory activity correlated with the biogenesis of the sporoderm. Conclusion Our present data provide support for a key role of CRT in developing anther of angiosperms – regulation of Ca2+ homeostasis during pollen grains formation. This Ca2+-buffering chaperone seems to be essential for pollen development and maturation since a high rate of protein synthesis and protein folding within the ER as well as intracellular Ca2+ homeostasis are strictly required during the multi-step process of pollen development.

Structure, regulation and related diseases of the actin-binding protein gelsolin

2018 ◽  
Vol 20 ◽  
Author(s):  
Jessica Feldt ◽  
Martin Schicht ◽  
Fabian Garreis ◽  
Jessica Welss ◽  
Ulrich W. Schneider ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Immune System ◽  
Calcium Concentration ◽  
Actin Binding ◽  
Eukaryotic Cells ◽  
Potential Candidate ◽  
Cellular Interactions ◽  
Cellular Mechanisms ◽  
Functional Roles ◽  
Structure Regulation

AbstractGelsolin (GSN), one of the most abundant actin-binding proteins, is involved in cell motility, shape and metabolism. As a member of the GSN superfamily, GSN is a highly structured protein in eukaryotic cells that can be regulated by calcium concentration, intracellular pH, temperature and phosphatidylinositol-4,5-bisphosphate. GSN plays an important role in cellular mechanisms as well as in different cellular interactions. Because of its participation in immunologic processes and its interaction with different cells of the immune system, GSN is a potential candidate for various therapeutic applications. In this review, we summarise the structure of GSN as well as its regulating and functional roles, focusing on distinct diseases such as Alzheimer's disease, rheumatoid arthritis and cancer. A short overview of GSN as a therapeutic target in today's medicine is also provided.

scholarly journals Studies on the synthesis and intracellular transport of lipoprotein particles in rat liver.

1975 ◽  
Vol 64 (2) ◽  
pp. 356-377 ◽  
Author(s):  
H Glaumann ◽  
A Bergstrand ◽  
J L Ericsson
Keyword(s):  
Chemical Composition ◽  
Golgi Apparatus ◽  
Rat Liver ◽  
Golgi Complex ◽  
Intracellular Transport ◽  
High Rate ◽  
Very Low Density Lipoproteins ◽  
Lipoprotein Particles ◽  
Parallel Change ◽  
Rough Er

Lipoprotein particles (d less than 1.03 g/ml) were isolated from rough and smooth microsomes and from the Golgi apparatus of rat liver, and were characterized chemically and morphologically. The rough endoplasmic reticulum (ER) particles were rich in protein (50%) and contained phospholipids (PLP) and triglycerides (TG) in smaller amounts, whereas the lipoprotein particles emanating from the smooth ER, and especially the Golgi apparatus, were rich in TG and PLP, resembling very low density lipoproteins (VLDL) of serum. The difference in chemical composition among the particles was associated with change in size both in situ and in isolated lipoprotein fractions. The rough ER particles were 200-800 A in diameter (mean similar to 420 A); the smooth er particles 200-900 A (mean similar to 520 A); the Golgi particles 350-950 A (mean similar to 580A); and serum VLDL 300-800 A (mean similar to 450 A). Generally, lipoprotein particles were rare in the rough ER, frequent but diffusely dispersed in smooth ER, and occurring mainly in clusters in "secretory vesicles" of the Golgi complex. They were seldom observed in the cisternal compartments of the Golgi complex. At short intervals (less than 15 min), intravenously injected radioactive glycerol was preferentially channelled into TG, whereas at later time points the majority of the isotope was recovered in the PLP. Three TG pools were distinguished: (a) a cytoplasmic pool with a slow turnover rate; (b) a membrane-associated TG pool; and (c) a pool corresponding to the TG moiety of lipoprotein particles, which showed the highest initial rate of labeling and fastest turnover. When, after pulse labeling, the appearance of incorporation of radioactive glycerol into TG or PLP of isolated lipoproteins was followed from one subcellular fraction to the other, a sequence of labeling was noted. During the first interval, TG from both rough and smooth microsomal lipoproteins displayed a high rate of labeling with peak value at 6 min, followed by a quick fall-off, while the Golgi lipoproteins reached maximal level at 10-20 min after administration. There was an interval of 10-15 min before the appearance of labeled VLDL in serum. It is concluded that the assembly of the apoproteins and lipid moieties into lipoprotein particles-presumed to be precursors of liver VLDL-begins in the rough ER and continues in the smooth ER. Also, there is a parallel change in chemical composition and size of the lipoprotein particles as they make their way through the ER and the Golgi apparatus. Some remodeling of the particles may take place in the Golgi apparatus before discharge into the circulation.

Tapetum character states: analytical keys for tapetum types and activities

1997 ◽  
Vol 75 (9) ◽  
pp. 1448-1459 ◽  
Author(s):  
E. Pacini
Keyword(s):  
Pollen Development ◽  
Cell Walls ◽  
Pollen Grains ◽  
Cell Types ◽  
Plastid Differentiation ◽  
Pollen Coat ◽  
Tapetal Cells ◽  
Different Types ◽  
Compound Pollen ◽  
Pollen Formation

The different types of tapetum found in the spermatophyta are described, along with associated characters. The characters (taken singly, pairwise, or in multiple combinations) are (i) tapetum types; (ii) cell walls, tapetum types, and loculus; (iii) tapetal cells individually, tapetum types, and loculus; (iv) number of pollen grains enveloped by tapetal cells and type of pollen dispersing unit; (v) cell types and tapetum types; (vi) number of nuclei per cell and tapetum type; (vii) cycles of hyperactivity; (viii) exine formation; (ix) orbicles; (x) peritapetal membrane; (xi) plastid differentiation; (xii) stage of pollen development in which tapetal cells degenerate and type of pollen coat; (xiii) storage vacuoles; (xiv) sporophytic proteins; and (xv) devices of tapetal origin responsible for compound pollen formation and pollination. Examples are given and an analytical key of structural and functional diversity is provided as a helpful approach to the study of the tapetum. Key words: tapetum types, activities, pollen dispersing units.

scholarly journals Assembly and regulation of γ-tubulin complexes

Open Biology ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 170266 ◽  
Author(s):  
Dorian Farache ◽  
Laurent Emorine ◽  
Laurence Haren ◽  
Andreas Merdes
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Intracellular Transport ◽  
Eukaryotic Cells ◽  
Cellular Structures ◽  
Activator Proteins ◽  
Multiprotein Complexes ◽  
Microtubule Organizing Centres ◽  
Different Types ◽  
Ring Complexes

Microtubules are major constituents of the cytoskeleton in all eukaryotic cells. They are essential for chromosome segregation during cell division, for directional intracellular transport and for building specialized cellular structures such as cilia or flagella. Their assembly has to be controlled spatially and temporally. For this, the cell uses multiprotein complexes containing γ-tubulin. γ-Tubulin has been found in two different types of complexes, γ-tubulin small complexes and γ-tubulin ring complexes. Binding to adaptors and activator proteins transforms these complexes into structural templates that drive the nucleation of new microtubules in a highly controlled manner. This review discusses recent advances on the mechanisms of assembly, recruitment and activation of γ-tubulin complexes at microtubule-organizing centres.

scholarly journals Dynamin deficiency causes insulin secretion failure and hyperglycemia

2021 ◽  
Vol 118 (32) ◽  
pp. e2021764118
Author(s):  
Fan Fan ◽  
Yumei Wu ◽  
Manami Hara ◽  
Adam Rizk ◽  
Chen Ji ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Membrane Trafficking ◽  
High Rate ◽  
Dense Core Vesicle ◽  
Β Cells ◽  
Membrane Fission ◽  
Insulin Granules ◽  
Intracellular Ca ◽  
Mature Mouse ◽  
Second Phases

Pancreatic β cells operate with a high rate of membrane recycling for insulin secretion, yet endocytosis in these cells is not fully understood. We investigate this process in mature mouse β cells by genetically deleting dynamin GTPase, the membrane fission machinery essential for clathrin-mediated endocytosis. Unexpectedly, the mice lacking all three dynamin genes (DNM1, DNM2, DNM3) in their β cells are viable, and their β cells still contain numerous insulin granules. Endocytosis in these β cells is severely impaired, resulting in abnormal endocytic intermediates on the plasma membrane. Although insulin granules are abundant, their release upon glucose stimulation is blunted in both the first and second phases, leading to hyperglycemia and glucose intolerance in mice. Dynamin triple deletion impairs insulin granule exocytosis and decreases intracellular Ca2+ responses and granule docking. The docking defect is correlated with reduced expression of Munc13-1 and RIM1 and reorganization of cortical F-actin in β cells. Collectively, these findings uncover the role of dynamin in dense-core vesicle endocytosis and secretory capacity. Insulin secretion deficiency in the absence of dynamin-mediated endocytosis highlights the risk of impaired membrane trafficking in endocrine failure and diabetes pathogenesis.

scholarly journals Modulation of neuroglial interactions using differential target multiplexed spinal cord stimulation in an animal model of neuropathic pain

2020 ◽  
Vol 16 ◽  
pp. 174480692091805 ◽  
Author(s):  
Ricardo Vallejo ◽  
Courtney A Kelley ◽  
Ashim Gupta ◽  
William J Smith ◽  
Alejandro Vallejo ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Animal Model ◽  
Neuropathic Pain ◽  
Nerve Injury ◽  
Spinal Cord Stimulation ◽  
High Rate ◽  
Biological Processes ◽  
Cellular Interactions ◽  
Neuroglial Interactions ◽  
Low Rate

The development and maintenance of chronic neuropathic pain involves distorted neuroglial interactions, which result in prolonged perturbations of immune and inflammatory response, as well as disrupted synapses and cellular interactions. Spinal cord stimulation (SCS) has proven effective and safe for more than 40 years, but comprehensive understanding of its mode of action remains elusive. Previous work in our laboratory provided evidence that conventional SCS parameters modulate biological processes associated with neuropathic pain in animals. This inspired the development of differential target multiplexed programming (DTMP) in which multiple electrical signals are used for modulating glial cells and neurons in order to rebalance their interactions. This work compares DTMP with both low rate and high rate programming using an animal model of neuropathic pain. The spared nerve injury model was implemented in 48 rats equally randomized into four experimental groups: No-SCS, DTMP, low rate, and high rate. Naive animals (N = 7) served as a reference control. SCS was applied continuously for 48 h and pain-related behavior assessed before and after SCS. RNA from the spinal cord exposed to SCS was sequenced to determine changes in gene expression as a result of injury (No-SCS vs. naïve) and as a result of SCS (SCS vs. No-SCS). Bioinformatics tools (Weighted Gene Co-expression Network Analysis and Gene Ontology Enrichment Analysis) were used to evaluate the significance of the results. All three therapies significantly reduced mechanical hypersensitivity, although DTMP provided statistically better results overall. DTMP also reduced thermal hypersensitivity significantly. RNA-sequencing corroborated the complex effects of nerve injury on the transcriptome. In addition, DTMP provided significantly more effective modulation of genes associated with pain-related processes in returning their expression toward levels observed in naïve, noninjured animals. DTMP provides a more effective way of modulating the expression of genes involved in pain-relevant biological processes associated with neuroglial interactions.

Extracellular effect of calcium on compound 48/80 stimulated mast cells

1983 ◽  
Vol 61 (1) ◽  
pp. 79-84 ◽  
Author(s):  
Narendranath S. Ranadive ◽  
Rubina Lewis
Keyword(s):  
Mast Cells ◽  
Histamine Release ◽  
High Concentration ◽  
Extracellular Concentration ◽  
Exchangeable Ca ◽  
Intracellular Ca ◽  
Kinetics Of ◽  
Rat Mast Cells

The effects of changes in the extracellular concentration of calcium on activation of rat mast cells by compound 48/80 were studied. The intracellular exchangeable Ca2+ pools at various concentrations of extracellular Ca2+ were determined by equilibration of the cells with 45Ca2+. The cells stimulated by compound 48/80 in the presence of 2.5 μM and 1.6 mM extracellular Ca2+ released comparable amounts of histamine. However, the intracellular Ca2+ pool was doubled in 2.5 μM Ca2+ and was increased sixfold in 1.6 mM Ca2+. In 14.4 mM extracellular Ca2+, there was neither release of histamine nor uptake of Ca2+ which suggested an impairment in activation. The kinetics of Ca2+ influx in the presence of 2.5 μM Ca2+ did not reveal intracellular mobilization of calcium. The cells activated in 1.6 mM Ca2+ at 0 °C when allowed to stand in 14.4 mM extracellular Ca2+ released decreased amounts of histamine upon warming to 37 °C. The inhibition of the release progressively increased with time of standing at 0 °C. The decrease in histamine release was not seen with the cells standing in 1.6 mM Ca2+ at 0 °C. The effect of 14.4 mM Ca2+ added prior to the challenge with compound 48/80 did not depend on the time of incubation. The data presented in this paper suggest that the high concentration of Ca2+ inhibits the histamine release from mast cells by interfering with membrane-associated phenomena.

scholarly journals The yeast p24 complex regulates GPI-anchored protein transport and quality control by monitoring anchor remodeling

2011 ◽  
Vol 22 (16) ◽  
pp. 2924-2936 ◽  
Author(s):  
Guillaume A. Castillon ◽  
Auxiliadora Aguilera-Romero ◽  
Javier Manzano-Lopez ◽  
Sharon Epstein ◽  
Kentaro Kajiwara ◽  
...  
Keyword(s):  
Quality Control ◽  
Endoplasmic Reticulum ◽  
Cell Surface ◽  
Intracellular Transport ◽  
Protein Transport ◽  
Eukaryotic Cells ◽  
Secretory Proteins ◽  
Dependent Manner ◽  
Gpi Anchor ◽  
The Status

Glycosylphosphatidylinositol (GPI)-anchored proteins are secretory proteins that are attached to the cell surface of eukaryotic cells by a glycolipid moiety. Once GPI anchoring has occurred in the lumen of the endoplasmic reticulum (ER), the structure of the lipid part on the GPI anchor undergoes a remodeling process prior to ER exit. In this study, we provide evidence suggesting that the yeast p24 complex, through binding specifically to GPI-anchored proteins in an anchor-dependent manner, plays a dual role in their selective trafficking. First, the p24 complex promotes efficient ER exit of remodeled GPI-anchored proteins after concentration by connecting them with the COPII coat and thus facilitates their incorporation into vesicles. Second, it retrieves escaped, unremodeled GPI-anchored proteins from the Golgi to the ER in COPI vesicles. Therefore the p24 complex, by sensing the status of the GPI anchor, regulates GPI-anchored protein intracellular transport and coordinates this with correct anchor remodeling.

scholarly journals A Deep Learning-Based System (Microscan) for the Identification of Pollen Development Stages and Its Application to Obtaining Doubled Haploid Lines in Eggplant

Biology ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 272
Author(s):  
Edgar García-Fortea ◽  
Ana García-Pérez ◽  
Esther Gimeno-Páez ◽  
Alfredo Sánchez-Gimeno ◽  
Santiago Vilanova ◽  
...  
Keyword(s):  
Deep Learning ◽  
High Throughput ◽  
Pollen Development ◽  
High Rate ◽  
Genotyping Platform ◽  
Enrichment Technology ◽  
Pure Lines ◽  
Single Primer

The development of double haploids (DHs) is a straightforward path for obtaining pure lines but has multiple bottlenecks. Among them is the determination of the optimal stage of pollen induction for androgenesis. In this work, we developed Microscan, a deep learning-based system for the detection and recognition of the stages of pollen development. In a first experiment, the algorithm was developed adapting the RetinaNet predictive model using microspores of different eggplant accessions as samples. A mean average precision of 86.30% was obtained. In a second experiment, the anther range to be cultivated in vitro was determined in three eggplant genotypes by applying the Microscan system. Subsequently, they were cultivated following two different androgenesis protocols (Cb and E6). The response was only observed in the anther size range predicted by Microscan, obtaining the best results with the E6 protocol. The plants obtained were characterized by flow cytometry and with the Single Primer Enrichment Technology high-throughput genotyping platform, obtaining a high rate of confirmed haploid and double haploid plants. Microscan has been revealed as a tool for the high-throughput efficient analysis of microspore samples, as it has been exemplified in eggplant by providing an increase in the yield of DHs production.

Effect of an acidifying nitrogen fertiliser and lime on soil pH and wheat yields. 1. Soil effects

1994 ◽  
Vol 34 (2) ◽  
pp. 237 ◽  
Author(s):  
MG Mason ◽  
WM Porter ◽  
WJ Cox
Keyword(s):  
Soil Ph ◽  
Ammonium Phosphate ◽  
High Rate ◽  
Continuous Cropping ◽  
Exchangeable Ca ◽  
Acid Accumulation ◽  
Soil Effects ◽  
P Application ◽  
Over Time

Three long-term trials were commenced in 1980 at Merredin, Wongan Hills, and Newdegate to investigate the effect of an acidifying fertiliser containing 17.5% nitrogen (N) and 7.6% phosphorus (P) (based on ammonium sulfate and ammonium phosphate) on soil pH, soil acidity related problems, and wheat grain yields under continuous cropping. Treatments were 3 rates (kg/ha) of N + P applied with the cereal seed (nil; 17.5 N + 7.6 P; 35 N + 15.2 P), with or without 3 t/ha of ground limestone (with or without MgSO4, KCl, Moo3) applied in 1980. Two extra treatments were 2 rates of limestone (70, 140 kg/ha) topdressed with the cereal crop each year along with the low and high N + P fertiliser treatments, respectively. This paper reports soil properties for the first 10 years of the trials. In the acidic Merredin soil (pH 4.3), there was minimal effect of N + P fertiliser on soil pH. The pH was slightly reduced at 0-10 cm depth. At Wongan Hills, soil pH at 0-10 cm depth was reduced over time by N + P application from 4.8 to 4.2. At Newdegate, only the high rate of N + P reduced pH over time, from 4.6 to 4.3 at 0-10 cm. Limestone at 3 t/ha in 1980 increased soil pH at 0-10 cm depth at all 3 sites; however, in all cases pH fell with time. Limestone applied at 70 or 140 kgha with each N + P application increased pH at 0-10 cm depth by 0.1-0.4, 0.1-0.4, and 0.3-0.9 pH units at Merredin, Wongan Hills, and Newdegate. Soil aluminium (Al) concentrations (extracted in 0.01 mol CaCl2/L) were generally low at Wongan Hills and Newdegate in the absence of N + P fertiliser. These levels rose after N + P application to 4 and 2 �g/g at 0-10 cm depth at Wongan Hills and Newdegate. Soil A1 concentrations at Merredin were high, particularly in the subsoil: 3-5, 9-13, and 23-29 �g/g in the 0-10, 10-20, and 20-40 cm depths. With the high rate of N + P, A1 concentration rose to 10 �g/g at 0-10 cm. Application of 3 t/ha of limestone reduced this to <1-2 �g/g. Application of 140 kg/ha of limestone with the high N + P fertiliser rate lowered soil A1 concentration at 0-10 cm. Extra acid that accumulated in treated plots compared with control plots varied from -34.7 kmol/ha (acid-neutralised) for the treatment at Merredin receiving only 3 t lime/ha in 1980 to 23.8 kmol/ha for the treatment at Wongan Hills receiving high N + P. With the treatments receiving lime only, the amounts of acid neutralised were only 82, 66, and 58% of those predicted at Merredin, Wongan Hills, and Newdegate, respectively. Acid accumulation in the 3 treatments receiving high N + P was within the predicted range at Wongan Hills, as it was for the treatment receiving high N + P plus 3 t lime/ha in 1980 at both Merredin and Newdegate. However, for the treatments receiving only high N + P or high N + P plus 140 kg lime/ha. year at these 2 sites, the acid accumulation rates were less than predicted. Levels of exchangeable cations in the soil were highest at Wongan Hills and lowest at Newdegate. Application of N + P decreased Ca concentration at all sites and reduced the concentration of exchangeable Mg at Wongan Hills. Lime applied at 3 t/ha increased the concentrations of exchangeable Ca and Mg at all sites. There were no effects of treatments on concentrations of exchangeable K or sodium.

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