scholarly journals Can retinal adhesion mechanisms determine cell-sorting patterns: a test of the differential adhesion hypothesis

Development ◽  
1988 ◽  
Vol 103 (1) ◽  
pp. 37-48
Author(s):  
W.A. Thomas ◽  
J. Yancey
Keyword(s):  
Cell Sorting ◽  
Cell Aggregation ◽  
Adhesion Mechanism ◽  
Differential Adhesion ◽  
Contrast Microscopy ◽  
Retinal Adhesion ◽  
Differential Adhesion Hypothesis

Embryonic chick neural retina cells possess two classes of adhesion mechanism, one Ca2+-independent, one Ca2+-dependent, responsible for short-term cell aggregation. This study investigates the role of these mechanisms in the long-term cell sorting potentially relevant to in vivo histogenesis. Retina cells are prepared either with both (E cells) or with only one mechanism (TC cells, CD; LTE cells, CI), respectively. The two types of cell preparations are differentially labelled using fluorescein or rhodamine isothiocyanate, mixed and allowed to aggregate in the presence or absence of cycloheximide at 0.5 microgram ml-1 to retard metabolic recovery of the removed adhesive mechanism. When observed by fluorescence and phase-contrast microscopy, the aggregates formed in cycloheximide show cell sorting, the cells with both mechanisms assuming a more interior position relative to those with a single adhesion mechanism. In parallel hanging-drop experiments, preformed aggregates of cells with a single adhesion mechanism are seen to spread upon aggregates of cells with both mechanisms. No sorting occurs amongst cells from a given stage prepared using any single dissociation protocol. The observed cell sorting would thus seem to derive exclusively from differential cell adhesiveness dependent upon the different dissociation conditions and maintained in the presence of cycloheximide. The experiments support the hypothesis that the dual CI and CD adhesion mechanisms in question can play a central role in governing cell-sorting behaviour during normal histogenesis.

THE ROLE OF POLYETHYLENIMINE IN ENHANCING PERFORMANCE OF GLUTAMATE BIOSENSORS

2018 ◽  
Vol 8 (3) ◽  
pp. 36-41
Author(s):  
Diep Do Thi Hong ◽  
Duong Le Phuoc ◽  
Hoai Nguyen Thi ◽  
Serra Pier Andrea ◽  
Rocchitta Gaia
Keyword(s):  
First Generation ◽  
Good Reproducibility ◽  
Complex Matrices ◽  
Long Term Stability ◽  
In Vitro Characterization ◽  
Glutamate Oxidase

Background: The first biosensor was constructed more than fifty years ago. It was composed of the biorecognition element and transducer. The first-generation enzyme biosensors play important role in monitoring neurotransmitter and determine small quantities of substances in complex matrices of the samples Glutamate is important biochemicals involved in energetic metabolism and neurotransmission. Therefore, biosensors requires the development a new approach exhibiting high sensibility, good reproducibility and longterm stability. The first-generation enzyme biosensors play important role in monitoring neurotransmitter and determine small quantities of substances in complex matrices of the samples. The aims of this work: To find out which concentration of polyethylenimine (PEI) exhibiting the most high sensibility, good reproducibility and long-term stability. Methods: We designed and developed glutamate biosensor using different concentration of PEI ranging from 0% to 5% at Day 1 and Day 8. Results: After Glutamate biosensors in-vitro characterization, several PEI concentrations, ranging from 0.5% to 1% seem to be the best in terms of VMAX, the KM; while PEI content ranging from 0.5% to 1% resulted stable, PEI 1% displayed an excellent stability. Conclusions: In the result, PEI 1% perfomed high sensibility, good stability and blocking interference. Furthermore, we expect to develop and characterize an implantable biosensor capable of detecting glutamate, glucose in vivo. Key words: Glutamate biosensors, PEi (Polyethylenimine) enhances glutamate oxidase, glutamate oxidase biosensors

Neurofilament phosphorylation

1995 ◽  
Vol 73 (9-10) ◽  
pp. 575-592 ◽  
Author(s):  
Harish C. Pant ◽  
Veeranna
Keyword(s):  
Molecular Weight ◽  
Nervous System ◽  
Nervous Tissue ◽  
Important Determinant ◽  
Neurofilament Proteins ◽  
Neurofilament Phosphorylation ◽  
Axonal Compartment

Neurofilament proteins (NFPs) are highly phosphorylated molecules in the axonal compartment of the adult nervous system. The phosphorylation of NFP is considered an important determinant of filament caliber, plasticity, and stability. This process reflects the function of NFs during the lifetime of a neuron from differentiation in the embryo through long-term activity in the adult until aging and environmental insult leads to pathology and ultimately death. NF function is modulated by phosphorylation–dephosphorylation in each of these diverse neuronal states. In this review, we have summarized some of these properties of NFP in adult nervous tissue, mostly from work in our own laboratory. Identification of sites phosphorylated in vivo in high molecular weight NFP (NF-H) and properties of NF-associated and neural-specific kinases phosphorylating specific sites in NFP are described. A model to explain the role of NF phosphorylation in determining filament caliber, plasticity, and stability is proposed.Key words: neurofilament proteins, phosphorylation, kinases, phosphatases, regulators, inhibitors, multimesic complex, domains.

scholarly journals Short-term and long-term role of platelet activating factor as a mediator of in vivo platelet aggregation.

Circulation ◽  
1993 ◽  
Vol 88 (3) ◽  
pp. 1205-1214 ◽  
Author(s):  
P Golino ◽  
G Ambrosio ◽  
M Ragni ◽  
I Pascucci ◽  
M Triggiani ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activating Factor ◽  
Short Term

Correlation between magnesium and potassium contents in muscle: role of Na(+)-K+ pump

1993 ◽  
Vol 264 (2) ◽  
pp. C457-C463 ◽  
Author(s):  
I. Dorup ◽  
T. Clausen
Keyword(s):  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Deficient Diet ◽  
Young Rats ◽  
Wide Range ◽  
86Rb Influx

In young rats fed a Mg(2+)-deficient diet for 3 wk, Mg2+ and K+ contents in soleus and extensor digitorum longus muscles were significantly reduced and closely correlated. In isolated soleus muscles, Mg2+ depletion induced an even more pronounced loss of K+, and Mg2+ and K+ contents were correlated over a wide range (r = 0.95, P < 0.001). Extracellular Mg2+ (0-1.2 mM) caused no change in total or ouabain-suppressible 86Rb influx. After long-term incubation in Ca(2+)-Mg(2+)-free buffer with EDTA and EGTA, cellular Mg2+ and K+ contents were reduced by 35 and 15%, respectively, without any reduction in ATP and total or ouabain-suppressible 86Rb influx. In Mg(2+)-depleted muscles 42K efflux was increased by up to 42%, and repletion with Mg2+ produced a graded decrease. We conclude that Mg2+ and K+ contents are closely correlated in muscles Mg2+ depleted in vivo or in vitro and that neither extracellular nor moderate intracellular Mg2+ depletion affects total or Na(+)-K+ pump-mediated K+ influx. The reduced K+ content may rather be related to increased K+ efflux from the muscles.

scholarly journals Role of epigenetic effectors in maintenance of the long-term persistent bystander effect in spleen in vivo

2007 ◽  
Vol 28 (8) ◽  
pp. 1831-1838 ◽  
Author(s):  
Igor Koturbash ◽  
Alex Boyko ◽  
Rocio Rodriguez-Juarez ◽  
Robert J. McDonald ◽  
Volodymyr P. Tryndyak ◽  
...  
Keyword(s):  
Bystander Effect

scholarly journals Dynamics of intravital concentration of amino acid metabolites in human brain in post-traumatic period

2019 ◽  
Vol 484 (2) ◽  
pp. 238-242
Author(s):  
N. A. Semenova ◽  
P. E. Menshchikov ◽  
A. V. Manzhurtsev ◽  
M. V. Ublinskiy ◽  
T. A. Akhadov ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Amino Acid ◽  
Human Brain ◽  
Leading Role ◽  
Acid Metabolites ◽  
Post Traumatic ◽  
First Time

Intracellular concentrations of N acetyaspartate (NAA), aspartate (Asp) and glutamate (Glu) were determined for the first time in human brain in vivo, and the effect of severe traumatic brain injury on NAA synthesis in acute and late post-traumatic period was investigated. In MRI‑negative frontal lobes one day after injury Asp and Glu levels were found to decrease by 45 and 35%, respectively, while NAA level decreased by only 16%. A negative correlation between NAA concentration and the ratio of Asp/Glu concentrations was found. In the long-term period, Glu level returned to normal, Asp level remained below normal by 60%, NAA level was reduced by 65% relative to normal, and Asp/Glu ratio significantly decreased. The obtained results revealed leading role of the neuronal aspartate-malate shuttle in violation of NAA synthesis.

scholarly journals Rac signaling in osteoblastic cells is required for normal bone development but is dispensable for hematopoietic development

Blood ◽  
2012 ◽  
Vol 119 (3) ◽  
pp. 736-744 ◽  
Author(s):  
Steven W. Lane ◽  
Serena De Vita ◽  
Kylie A. Alexander ◽  
Ruchan Karaman ◽  
Michael D. Milsom ◽  
...  
Keyword(s):  
Bone Growth ◽  
Bone Development ◽  
Long Bone ◽  
Perivascular Niche ◽  
Hematopoietic Stem ◽  
Hsc Niche ◽  
Rac1 Gtpase

Abstract Hematopoietic stem cells (HSCs) interact with osteoblastic, stromal, and vascular components of the BM hematopoietic microenvironment (HM) that are required for the maintenance of long-term self-renewal in vivo. Osteoblasts have been reported to be a critical cell type making up the HSC niche in vivo. Rac1 GTPase has been implicated in adhesion, spreading, and differentiation of osteoblast cell lines and is critical for HSC engraftment and retention. Recent data suggest a differential role of GTPases in endosteal/osteoblastic versus perivascular niche function. However, whether Rac signaling pathways are also necessary in the cell-extrinsic control of HSC function within the HM has not been examined. In the present study, genetic and inducible models of Rac deletion were used to demonstrate that Rac depletion causes impaired proliferation and induction of apoptosis in the OP9 cell line and in primary BM stromal cells. Deletion of Rac proteins caused reduced trabecular and cortical long bone growth in vivo. Surprisingly, HSC function and maintenance of hematopoiesis in vivo was preserved despite these substantial cell-extrinsic changes. These data have implications for therapeutic strategies to target Rac signaling in HSC mobilization and in the treatment of leukemia and provide clarification to our evolving concepts of HSC-HM interactions.

scholarly journals The tight junctions protein Claudin-5 limits endothelial cell motility

2020 ◽  
pp. jcs.248237
Author(s):  
Zhenguo Yang ◽  
Shuilong Wu ◽  
Federica Fontana ◽  
Yanyu Li ◽  
Wei Xiao ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Cell Motility ◽  
Dorsal Aorta ◽  
Aortic Endothelial Cells ◽  
Differential Adhesion ◽  
Adhesive Forces

Steinberg's differential adhesion hypothesis suggests that adhesive mechanisms are important for sorting of cells and tissues during morphogenesis (Steinberg, 2007). During zebrafish vasculogenesis, endothelial cells sort into arterial and venous vessel beds but it is unknown whether this involves adhesive mechanisms. Claudins are tight junction proteins regulating the permeability of epithelial and endothelial tissue barriers. Previously, the roles of Claudins during organ development have exclusively been related to their canonical functions in determining paracellular permeability. Here, we use atomic force microscopy to quantify Claudin-5-dependent adhesion and find that this strongly contributes to the adhesive forces between arterial endothelial cells. Based on genetic manipulations, we reveal a non-canonical role of Claudin-5a during zebrafish vasculogenesis, which involves the regulation of adhesive forces between adjacent dorsal aortic endothelial cells. In vitro and in vivo studies demonstrate that loss of Claudin-5 results in increased motility of dorsal aorta endothelial cells and in a failure of the dorsal aorta to lumenize. Our findings uncover a novel role of Claudin-5 in limiting arterial endothelial cell motility, which goes beyond its traditional sealing function during embryonic development.

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