scholarly journals Centrin plays an essential role in microtubule severing during flagellar excision in Chlamydomonas reinhardtii

1994 ◽  
Vol 124 (5) ◽  
pp. 795-805 ◽  
Author(s):  
MA Sanders ◽  
JL Salisbury
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Transition Zone ◽  
Cell Model ◽  
Inhibitory Effect ◽  
Free Calcium ◽  
Cell Models ◽  
Microtubule Severing ◽  
Cell Biol ◽  
Molecular Machinery ◽  
D Cells

Previously, we reported that flagellar excision in Chlamydomonas reinhardtii is mediated by an active process whereby microtubules are severed at select sites within the flagellar-basal body transition zone (Sanders, M. A., and J. L. Salisbury. 1989. J. Cell Biol. 108:1751-1760). At the time of flagellar excision, stellate fibers of the transition zone contract and displace the microtubule doublets of the axoneme inward. The resulting shear force and torsional load generated during inward displacement leads to microtubule severing immediately distal to the central cylinder of the transition zone. In this study, we have used a detergent-extracted cell model of Chlamydomonas that allows direct experimental access to the molecular machinery responsible for microtubule severing without the impediment of the plasma membrane. We present four independent lines of experimental evidence for the essential involvement of centrin-based stellate fibers of the transition zone in the process of flagellar excision: (a) Detergent-extracted cell models excise their flagella in response to elevated, yet physiological, levels of free calcium. (b) Extraction of cell models with buffers containing the divalent cation chelator EDTA leads to the disassembly of centrin-based fibers and to the disruption of transition zone stellate fiber structure. This treatment results in a complete loss of flagellar excision competence. (c) Three separate anti-centrin monoclonal antibody preparations, which localize to the stellate fibers of the transition zone, specifically inhibit contraction of the stellate fibers and block calcium-induced flagellar excision, while control antibodies have no inhibitory effect. Finally, (d) cells of the centrin mutant vfl-2 (Taillon, B., S. Adler, J. Suhan, and J. Jarvik. 1992. J. Cell Biol. 119:1613-1624) fail to actively excise their flagella following pH shock in living cells or calcium treatment of detergent-extracted cell models. Taken together, these observations demonstrate that centrin-based fiber contraction plays a fundamental role in microtubule severing at the time of flagellar excision in Chlamydomonas.

scholarly journals Two distinct, calcium-mediated, signal transduction pathways can trigger deflagellation in Chlamydomonas reinhardtii

1994 ◽  
Vol 124 (5) ◽  
pp. 807-815 ◽  
Author(s):  
LM Quarmby ◽  
HC Hartzell
Keyword(s):  
Signal Transduction ◽  
Chlamydomonas Reinhardtii ◽  
Living Cells ◽  
Signalling Pathways ◽  
Signal Transduction Pathways ◽  
Channel Blockers ◽  
Wasp Venom ◽  
Intracellular Pool ◽  
Cell Biol ◽  
Molecular Machinery

The molecular machinery of deflagellation can be activated in detergent permeabilized Chlamydomonas reinhardtii by the addition of Ca2+ (Sanders, M. A., and J. L. Salisbury, 1989. J. Cell Biol. 108:1751-1760). This suggests that stimuli which induce deflagellation in living cells cause an increase in the intracellular concentration of Ca2+, but this has never been demonstrated. In this paper we report that the wasp venom peptide, mastoparan, and the permeant organic acid, benzoate, activate two different signalling pathways to trigger deflagellation. We have characterized each pathway with respect to: (a) the requirement for extracellular Ca2+; (b) sensitivity to Ca2+ channel blockers; and (c) 45Ca influx. We also report that a new mutant strain of C. reinhardtii, adf-1, is specifically defective in the acid-activated signalling pathway. Both signalling pathways appear normal in another mutant, fa-1, that is defective in the machinery of deflagellation (Lewin, R. and C. Burrascano. 1983. Experientia. 39:1397-1398; Sanders, M. A., and J. L. Salisbury. 1989. J. Cell Biol. 108:1751-1760). We conclude that mastoparan induces the release of an intracellular pool of Ca2+ whereas acid induces an influx of extracellular Ca2+ to activate the machinery of deflagellation.

scholarly journals NPHP proteins: gatekeepers of the ciliary compartment

2010 ◽  
Vol 190 (5) ◽  
pp. 715-717 ◽  
Author(s):  
Heymut Omran
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Transition Zone ◽  
Structural Integrity ◽  
Ciliary Membrane ◽  
Integral Component ◽  
Cell Biol

The cilia and the cytoplasm are separated by a region called the transition zone, where wedge-shaped structures link the microtubule doublets of the axoneme to the ciliary membrane, thereby forming a ciliary “gate.” In this issue, Craige et al. (J. Cell Biol. doi:10.1083/jcb.201006105) demonstrate in Chlamydomonas reinhardtii that Nphp6/cep290, which is mutated in nephronophthisis (NPHP), is an integral component of these connectors and maintains the structural integrity of this gate.

scholarly journals The Novel Alpha-2 Adrenoceptor Inhibitor Beditin Reduces Cytotoxicity and Huntingtin Aggregates in Cell Models of Huntington’s Disease

2021 ◽  
Vol 14 (3) ◽  
pp. 257
Author(s):  
Elisabeth Singer ◽  
Lilit Hunanyan ◽  
Magda M. Melkonyan ◽  
Jonasz J. Weber ◽  
Lusine Danielyan ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Neurodegenerative Disorder ◽  
Cell Model ◽  
Resonance Energy Transfer ◽  
Neuronal Cell ◽  
Resonance Energy ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Tunel Staining ◽  
Cell Models

Huntington’s disease (HD) is a monogenetic neurodegenerative disorder characterized by the accumulation of polyglutamine-expanded huntingtin (mHTT). There is currently no cure, and therefore disease-slowing remedies are sought to alleviate symptoms of the multifaceted disorder. Encouraging findings in Alzheimer’s and Parkinson’s disease on alpha-2 adrenoceptor (α2-AR) inhibition have shown neuroprotective and aggregation-reducing effects in cell and animal models. Here, we analyzed the effect of beditin, a novel α2- adrenoceptor (AR) antagonist, on cell viability and mHTT protein levels in cell models of HD using Western blot, time-resolved Foerster resonance energy transfer (TR-FRET), lactate dehydrogenase (LDH) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) cytotoxicity assays. Beditin decreases cytotoxicity, as measured by TUNEL staining and LDH release, in a neuronal progenitor cell model (STHdh cells) of HD and decreases the aggregation propensity of HTT exon 1 fragments in an overexpression model using human embryonic kidney (HEK) 293T cells. α2-AR is a promising therapeutic target for further characterization in HD models. Our data allow us to suggest beditin as a valuable candidate for the pharmaceutical manipulation of α2-AR, as it is capable of modulating neuronal cell survival and the level of mHTT.

Meshfree Continuum Damage Mechanics Modelling for 3D Orthogonal Woven Composites

2011 ◽  
Vol 488-489 ◽  
pp. 759-762
Author(s):  
L.Y. Li ◽  
M.H. Aliabadi ◽  
Pi Hua Wen
Keyword(s):  
Damage Mechanics ◽  
Shape Function ◽  
Cell Model ◽  
Continuum Damage Mechanics ◽  
Unit Cell ◽  
Woven Composites ◽  
Continuum Damage ◽  
Unit Cell Model ◽  
Cell Models ◽  
3D Orthogonal Woven

A Meshfree approach for continuum damage modeling of 3D orthogonal woven composites is presented. Two different shape function constructions, Radial basis (RB) function and Moving kriging (MK) interpolation, are utilized corresponding with Galerkin method in the Meshfree approach. The failure of two different unit cell models, straight-edge and smooth fabric unit cell model respectively, is compared.

scholarly journals Inhibition of Human Efflux Transporter ABCC2 (MRP2) by Self-emulsifying Drug Delivery System: Influences of Concentration and Combination of Excipients

2014 ◽  
Vol 17 (4) ◽  
pp. 447 ◽  
Author(s):  
Liang Li ◽  
Tao Yi ◽  
Christopher Wai-kei Lam
Keyword(s):  
Drug Delivery ◽  
Atpase Activity ◽  
Cell Model ◽  
Ultra Performance Liquid Chromatography ◽  
Inhibitory Effect ◽  
Combined Effects ◽  
Efflux Transporter ◽  
Peg 400 ◽  
Efflux Ratio ◽  
Liquid Chromatography Tandem Mass

PURPOSE: This study investigated influences of concentration and combination of excipients, commonly used in self-emulsifying drug delivery systems (SEDDS), on inhibition of human efflux transporter ABCC2 (MRP2). METHODS: Ten commonly used excipients of SEDDS with inhibitory effect on MRP2 including Cremophor® EL, Cremophor® RH, Pluronic® F127, Maisine® 35-1, β-cyclodextrin, Labrasol®, Pluronic® F68, PEG 2000, PEG 400 and Transcutol® were studied with the Caco-2 cell model. Six excipients with inhibitory effect including Cremophor® EL, Cremophor® RH, Pluronic® F127, PEG 2000, PEG 400 and Transcutol® were further analyzed using the MRP2 vesicle assay and ATPase activity assay. Ultra-performance liquid-chromatography tandem mass spectrometry was used to measure scutellarin as the MRP2 substrate. RESULTS: In studying concentration-dependent effects, five excipients including Cremophor® EL, Cremophor® RH, Pluronic® F127, Maisine® 35-1 and β-cyclodextrin showed concentration-dependent decrease in efflux ratio of scutellarin. The other five excipients did not show such phenomenon, and their inhibitory effects were restricted to be above to certain critical or minimum concentrations. In studying combined effects, PEG 2000 and Pluronic® F127 both showed combined effect with Cremophor® EL on inhibiting MRP2. However, some combinations of excipients such as PEG 400　and Transcutol® with Cremophor® EL increased the scutellarin efflux ratio and decreased the transport of scutellarin and ATPase activity, compared to Cremophor® EL alone. CONCLUSION: The above results suggest that appropriate choice of excipients according to their concentration-dependent and combined effects on MRP2 inhibition can facilitate formulation of SEDDS for improving the bioavailability of drugs that are MRP2 substrates. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

EQUIVALENT CNN CELL MODELS AND PATTERNS

2003 ◽  
Vol 13 (05) ◽  
pp. 1055-1161 ◽  
Author(s):  
MAKOTO ITOH ◽  
LEON O. CHUA
Keyword(s):  
Genetic Algorithms ◽  
Wave Propagation ◽  
Pattern Formation ◽  
Discrete Time ◽  
Cell Model ◽  
Formation Mechanisms ◽  
Associative Memories ◽  
Cell Models ◽  
Canonical Models ◽  
Constrained Conditions

In this paper, canonical isolated CNN cell models are proposed by using implicit differential equations. A number of equivalent but distinct CNN cell models are derived from these canonical models. Almost every known CNN cell model can be classified into one or more groups via constrained conditions. This approach is also applied to discrete-time CNN cell models. Pattern formation mechanisms are investigated from the viewpoint of equivalent templates and genetic algorithms. A strange wave propagation phenomenon in nonuniform CNN cells is also presented in this paper. Finally, chaotic associative memories are proposed.

scholarly journals Down-Regulation of Inpp5e Associated With Abnormal Ciliogenesis During Embryonic Neurodevelopment Under Inositol Deficiency

2021 ◽  
Vol 12 ◽  
Author(s):  
Huixuan Yue ◽  
Shen Li ◽  
Jiaxing Qin ◽  
Tingting Gao ◽  
Jianjun Lyu ◽  
...  
Keyword(s):  
Primary Cilia ◽  
Cell Model ◽  
Gas Chromatography Mass Spectrometry ◽  
Enzyme Linked Immunosorbent Assay ◽  
Inositol Polyphosphate ◽  
Cell Models ◽  
Down Regulation ◽  
Nih3t3 Cells ◽  
Expression Levels ◽  
Brain Tissues

The inositol polyphosphate-5-phosphatase E (Inpp5e) gene is located on chromosome 9q34.3. The enzyme it encodes mainly hydrolyzes the 5-phosphate groups of phosphatidylinositol (3,4,5)-trisphosphate (PtdIns (3,4,5) P3) and phosphatidylinositol (4,5)-bisphosphate (PtdIns (4,5)P2), which are closely related to ciliogenesis and embryonic neurodevelopment, through mechanisms that are largely unknown. Here we studied the role of Inpp5e gene in ciliogenesis during embryonic neurodevelopment using inositol-deficiency neural tube defects (NTDs) mouse and cell models. Confocal microscopy and scanning electron microscope were used to examine the number and the length of primary cilia. The dynamic changes of Inpp5e expression in embryonic murine brain tissues were observed during Embryonic Day 10.5–13.5 (E 10.5–13.5). Immunohistochemistry, western blot, polymerase chain reaction (PCR) arrays were applied to detect the expression of Inpp5e and cilia-related genes of the embryonic brain tissues in inositol deficiency NTDs mouse. Real-time quantitative PCR (RT-qPCR) was used to validate the candidate genes in cell models. The levels of inositol and PtdIns(3,4) P2 were measured using gas chromatography-mass spectrometry (GC-MS) and enzyme linked immunosorbent assay (ELISA), respectively. Our results showed that the expression levels of Inpp5e gradually decreased in the forebrain tissues of the control embryos, but no stable trend was observed in the inositol deficiency NTDs embryos. Inpp5e expression in inositol deficiency NTDs embryos was significantly decreased compared with the control tissues. The expression levels of Inpp5e gene and the PtdIns (3,4) P2 levels were also significantly decreased in the inositol deficient cell model. A reduced number and length of primary cilia were observed in NIH3T3 cells when inositol deficient. Three important cilia-related genes (Ift80, Mkks, Smo) were down-regulated significantly in the inositol-deficient NTDs mouse and cell models, and Smo was highly involved in NTDs. In summary, these findings suggested that down-regulation of Inpp5e might be associated with abnormal ciliogenesis during embryonic neurodevelopment, under conditions of inositol deficiency.

scholarly journals Inhibitory Effect of Edeine on Gametogenesis in Chlamydomonas reinhardtii

1993 ◽  
Vol 59 (10) ◽  
pp. 1805-1805
Author(s):  
Shigeki Sawayama ◽  
Yoshihiko Sako ◽  
Yuzaburo Ishida
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Inhibitory Effect

scholarly journals Anti-Allergic Potential of Cinnamaldehyde via the Inhibitory Effect of Histidine Decarboxylase (HDC) Producing Klebsiella pneumonia

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5580
Author(s):  
Lorina I. Badger-Emeka ◽  
Promise Madu Emeka ◽  
Krishnaraj Thirugnanasambantham ◽  
Hairul Islam M. Ibrahim
Keyword(s):  
Mast Cell ◽  
Cell Activation ◽  
Histidine Decarboxylase ◽  
Cell Model ◽  
In Vitro Study ◽  
Inhibitory Effect ◽  
Mast Cell Activation ◽  
Klebsiella Pneumonia ◽  
Immunological Disorder

Allergy is an immunological disorder that develops in response to exposure to an allergen, and histamines mediate these effects via histidine decarboxylase (HDC) activity at the intracellular level. In the present study, we developed a 3D model of Klebsiella pneumoniae histidine decarboxylase (HDC) and analyzed the HDC inhibitory potential of cinnamaldehyde (CA) and subsequent anti-allergic potential using a bacterial and mammalian mast cell model. A computational and in vitro study using K. pneumonia revealed that CA binds to HDC nearby the pyridoxal-5′-phosphate (PLP) binding site and inhibited histamine synthesis in a bacterial model. Further study using a mammalian mast cell model also showed that CA decreased the levels of histamine in the stimulated RBL-2H3 cell line and attenuated the release of β-hexoseaminidase and cell degranulation. In addition, CA treatment also significantly suppressed the levels of pro-inflammatory cytokines TNF-α and IL-6 and the nitric oxide (NO) level in the stimulated mast cells. A gene expression and Western blotting study revealed that CA significantly downregulated the expressions of MAPKp38/ERK and its downstream pro-allergic mediators that are involved in the signaling pathway in mast cell cytokine synthesis. This study further confirms that CA has the potential to attenuate mast cell activation by inhibiting HDC and modifying the process of allergic disorders.

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