Paracellular ion transport in trout opercular epithelium models osmoregulatory effects of acid precipitation

1985 ◽  
Vol 63 (8) ◽  
pp. 1816-1822 ◽  
Author(s):  
William S. Marshall
Keyword(s):  
Brook Trout ◽  
Intercellular Junctions ◽  
Acid Precipitation ◽  
Low Ph ◽  
Low Permeability ◽  
Ion Permeation ◽  
Common Pathway ◽  
Current Voltage ◽  
Acidic Environments

The opercular epithelium of brook trout, isolated in vitro in Ussing-style membrane chambers, is used to model the effects of acid precipitation on ion balance in fish. The epithelium normally has a low permeability to sodium, chloride, and mannitol, consistent with the barrier function of the skin. Treatment of the outside surface of the epithelium with low pH (threshold pH = 3.9) reversibly reduces transepithelial resistance (Rt). Reduction of outer pH to 3.61 ± 0.05 decreases Rt and increases the efflux of ions (Na+ and Cl−) and uncharged solutes, indicating that the epithelium rapidly and reversibly becomes leaky to solutes. Simultaneous mannitol and ion fluxes indicated that a common pathway, in which the solutes moved in relation to their free solution mobilities, is opened by low pH. The results are best explained by the acid-induced opening of a simple water-filled paracellular pathway. Low pH also altered the shape of nonlinear current-voltage relations, reducing the current density required to effect a reduction in Rt. The results are consistent with a model in which the titration by low pH of Ca2+ away from structural sites in the apical "tight" junctions weakens the intercellular junctions, thus leading to increased paracellular ion permeation. The effect may account in part for increased ion loss that leads to the morbidity of fish in soft-water acidic environments.

scholarly journals The Ethanolamine Permease EutH Promotes Vacuole Adaptation ofSalmonella entericaandListeria monocytogenesduring Macrophage Infection

2018 ◽  
Vol 86 (5) ◽  
Author(s):  
Christopher J. Anderson ◽  
John Satkovich ◽  
Volkan K. Köseoğlu ◽  
Hervé Agaisse ◽  
Melissa M. Kendall
Keyword(s):  
Low Ph ◽  
Bacterial Survival ◽  
Ecological Significance ◽  
Intestinal Infection ◽  
Macrophage Infection ◽  
Content Type ◽  
Niche Adaptation ◽  
Serovar Typhimurium ◽  
Acidic Environments

ABSTRACTEthanolamine is a ubiquitous and essential molecule within a host. Significantly, bacterial pathogens exploit ethanolamine during infection to promote growth and regulate virulence. The ethanolamine permease EutH is dispensable for growthin vitrounder standard conditions, whereas EutH is required for ethanolamine utilization at low pH. These findings suggested a model in which EutH facilitates diffusion of ethanolamine into the bacterial cell in acidic environments. To date, the ecological significance of this model has not been thoroughly investigated, and the importance of EutH to bacterial growth under physiologically relevant conditions is not known. During infection, immune cells internalize invading bacteria within an acidic, nutrient-depleted vacuole called the phagosome. Here, we investigated the hypothesis that EutH promotes bacterial survival following phagocytosis. Our findings indicate that EutH is important for survival and replication of the facultative intracellular pathogensSalmonella entericaserovar Typhimurium andListeria monocytogenesduring prolonged or transient exposure to the phagosome, respectively. Furthermore, in agreement with EutH being important in the acidic environment, neutralization of the vacuole abolished the requirement for EutH. Significantly, consistent with a role for EutH in promoting intramacrophage survival, EutH was not required duringS. Typhimurium local intestinal infection but specifically conferred an advantage upon dissemination to peripheral organs. These findings reveal a physiologically relevant and conserved role for EutH in spatiotemporal niche adaptation during infection.

Egg Hatchability and Tolerance of Brook Trout (Salvelinus fontinalis) Fry at Low pH

1977 ◽  
Vol 34 (4) ◽  
pp. 574-579 ◽  
Author(s):  
John R. Trojnar
Keyword(s):  
Key Words ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Acid Precipitation ◽  
Low Ph ◽  
Lake Acidification ◽  
Differential Mortality ◽  
Egg Hatchability

Hatchability of brook trout (Salvelinus fontinalis) eggs incubated at pH 4.6, 5.0, 5.6 and 8.0 ranged from 76 to 91%. Differential mortality was experienced when subsequent swim-up fry were exposed to a different pH indicating an acclimation effect. This suggests that brook trout fry incubated at lower, but sublethal, pH levels are less likely to experience acid-induced mortality upon emergence than those incubated in spring upwellings. Key words: low pH, brook trout, egg and fry mortality, acclimation, acid precipitation, lake acidification

Ultrastructural studies on the interaction of haemophilus influenzae with human endothelial cells in vitro

1990 ◽  
Vol 48 (3) ◽  
pp. 636-637
Author(s):  
D.J.P. Ferguson ◽  
M. Virji ◽  
H. Kayhty ◽  
E.R. Moxon
Keyword(s):  
Endothelial Cells ◽  
Haemophilus Influenzae ◽  
Intercellular Junctions ◽  
Blood Stream ◽  
Ultrastructural Studies ◽  
Endothelial Barriers ◽  
Serotype B ◽  
Meningitis In Children ◽  
Respiratory Epithelial

Haemophilus influenzae is a human pathogen which causes meningitis in children. Systemic H. influenzae infection is largely confined to encapsulated serotype b organisms and is a major cause of meningitis in the U.K. and elsewhere. However, the pathogenesis of the disease is still poorly understood. Studies in the infant rat model, in which intranasal challenge results in bacteraemia, have shown that H. influenzae enters submucosal tissues and disseminates to the blood stream within minutes. The rapidity of these events suggests that H. influenzae penetrates both respiratory epithelial and endothelial barriers with great efficiency. It is not known whether the bacteria penetrate via the intercellular junctions, are translocated within the cells or carried across the cellular barrier in 'trojan horse' fashion within phagocytes. In the present studies, we have challenged cultured human umbilical cord_vein endothelial cells (HUVECs) with both capsulated (b+) and capsule-deficient (b-) isogenic variants of one strain of H. influenzae in order to investigate the interaction between the bacteria and HUVEC and the effect of the capsule.

Morphilogy and Ultrastructure of in Vitro Cultures of Aortic Endothelial Cells Interacting with Antibodies

1979 ◽  
Author(s):  
S. Korach ◽  
D. Ngo
Keyword(s):  
Endothelial Cells ◽  
Cell Surface ◽  
Vascular Endothelial Cells ◽  
Intercellular Junctions ◽  
Cell Types ◽  
Endothelial Damage ◽  
Antibody Concentration ◽  
High Yields ◽  
Scanning Em

Adult pig aortas, sectioned longitudinally, were incubated in 0.1% collagenase-PBS (15 mn, 37°C). Gentle scraping of the lumenal surface resulted in high yields (3-4 x 106 cell/aorta) of viable endothelial cells, essentially devoid of other cell types by morphological and immunochemical (F VIII-antigen) criteria. Confluent monolayers were incubated for various times (5 mn to 1 wk) with decomplemented rabbit antisera raised against pig endothelial cells. Changes in cell morphology appeared to depend on antibody concentration rather than on duration of contact with antiserum. High concentrations of antiserum (5 to 20%) led to cytoplasmic shredding, bulging of cells and extensive vacuolization, whereas at lower concentrations, cells appeared almost normal. Transmission EM studies by the indirect immunoperoxydase method showed antibodies reacting with unfixed cells to be distributed all over the upper cell surface, in the outer parts of intercellular junctions, and within numerous pinocytotic vesicles. Much weaker reactions could also be seen at the lower cell surface. When viewed under the Scanning EM, antiserum-treated endothelial cells also disclosed antibody concentration-dependent bulging and release of cells from their substrate. In vitro studies of gradual modifications of vascular endothelial cells acted upon by antibodies should provide a better understanding of the structural and biochemical processes underlying endothelial damage and detachment.

scholarly journals Plectin ensures intestinal epithelial integrity and protects colon against colitis

2021 ◽  
Vol 14 (3) ◽  
pp. 691-702
Author(s):  
Alzbeta Krausova ◽  
Petra Buresova ◽  
Lenka Sarnova ◽  
Gizem Oyman-Eyrilmez ◽  
Jozef Skarda ◽  
...  
Keyword(s):  
Mechanical Stability ◽  
Intestinal Barrier ◽  
Intercellular Junctions ◽  
Protein Profiling ◽  
Cell Junctions ◽  
Intestinal Barrier Function ◽  
Intestinal Epithelial ◽  
Critical Determinant ◽  
In Vitro Feeding

AbstractPlectin, a highly versatile cytolinker protein, provides tissues with mechanical stability through the integration of intermediate filaments (IFs) with cell junctions. Here, we hypothesize that plectin-controlled cytoarchitecture is a critical determinant of the intestinal barrier function and homeostasis. Mice lacking plectin in an intestinal epithelial cell (IEC; PleΔIEC) spontaneously developed colitis characterized by extensive detachment of IECs from the basement membrane (BM), increased intestinal permeability, and inflammatory lesions. Moreover, plectin expression was reduced in the colons of ulcerative colitis (UC) patients and negatively correlated with the severity of colitis. Mechanistically, plectin deficiency in IECs led to aberrant keratin filament (KF) network organization and the formation of dysfunctional hemidesmosomes (HDs) and intercellular junctions. In addition, the hemidesmosomal α6β4 integrin (Itg) receptor showed attenuated association with KFs, and protein profiling revealed prominent downregulation of junctional constituents. Consistent with the effects of plectin loss in the intestinal epithelium, plectin-deficient IECs exhibited remarkably reduced mechanical stability and limited adhesion capacity in vitro. Feeding mice with a low-residue liquid diet that reduced mechanical stress and antibiotic treatment successfully mitigated epithelial damage in the PleΔIEC colon.

scholarly journals Furin Processing and Proteolytic Activation of Semliki Forest Virus

2003 ◽  
Vol 77 (5) ◽  
pp. 2981-2989 ◽  
Author(s):  
Xinyong Zhang ◽  
Martin Fugère ◽  
Robert Day ◽  
Margaret Kielian
Keyword(s):  
Conformational Changes ◽  
Secretory Pathway ◽  
Semliki Forest Virus ◽  
Fusion Reaction ◽  
Low Ph ◽  
Protein Fusion ◽  
Proteolytic Activation ◽  
Control Virus

ABSTRACT The alphavirus Semliki Forest virus (SFV) infects cells via a low-pH-dependent membrane fusion reaction mediated by the E1 envelope protein. Fusion is regulated by the interaction of E1 with the receptor-binding protein E2. E2 is synthesized as a precursor termed “p62,” which forms a stable heterodimer with E1 and is processed late in the secretory pathway by a cellular furin-like protease. Once processing to E2 occurs, the E1/E2 heterodimer is destabilized so that it is more readily dissociated by exposure to low pH, allowing fusion and infection. We have used FD11 cells, a furin-deficient CHO cell line, to characterize the processing of p62 and its role in the control of virus fusion and infection. p62 was not cleaved in FD11 cells and cleavage was restored in FD11 cell transfectants expressing human furin. Studies of unprocessed virus produced in FD11 cells (wt/p62) demonstrated that the p62 protein was efficiently cleaved by purified furin in vitro, without requiring prior exposure to low pH. wt/p62 virus particles were also processed during their endocytic uptake in furin-containing cells, resulting in more efficient virus infection. wt/p62 virus was compared with mutant L, in which p62 cleavage was blocked by mutation of the furin-recognition motif. wt/p62 and mutant L had similar fusion properties, requiring a much lower pH than control virus to trigger fusion and fusogenic E1 conformational changes. However, the in vivo infectivity of mutant L was more strongly inhibited than that of wt/p62, due to additional effects of the mutation on virus-cell binding.

scholarly journals Impact of the acidic environment on gene expression and functional parameters of tumors in vitro and in vivo

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Mandy Rauschner ◽  
Luisa Lange ◽  
Thea Hüsing ◽  
Sarah Reime ◽  
Alexander Nolze ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Death ◽  
Western Blot ◽  
Tumor Cell ◽  
Low Ph ◽  
Strong Increase ◽  
Acidic Ph ◽  
The Impact

Abstract Background The low extracellular pH (pHe) of tumors resulting from glycolytic metabolism is a stress factor for the cells independent from concomitant hypoxia. The aim of the study was to analyze the impact of acidic pHe on gene expression on mRNA and protein level in two experimental tumor lines in vitro and in vivo and were compared to hypoxic conditions as well as combined acidosis+hypoxia. Methods Gene expression was analyzed in AT1 prostate and Walker-256 mammary carcinoma of the rat by Next Generation Sequencing (NGS), qPCR and Western blot. In addition, the impact of acidosis on tumor cell migration, adhesion, proliferation, cell death and mitochondrial activity was analyzed. Results NGS analyses revealed that 147 genes were uniformly regulated in both cell lines (in vitro) and 79 genes in both experimental tumors after 24 h at low pH. A subset of 25 genes was re-evaluated by qPCR and Western blot. Low pH consistently upregulated Aox1, Gls2, Gstp1, Ikbke, Per3, Pink1, Tlr5, Txnip, Ypel3 or downregulated Acat2, Brip1, Clspn, Dnajc25, Ercc6l, Mmd, Rif1, Zmpste24 whereas hypoxia alone led to a downregulation of most of the genes. Direct incubation at low pH reduced tumor cell adhesion whereas acidic pre-incubation increased the adhesive potential. In both tumor lines acidosis induced a G1-arrest (in vivo) of the cell cycle and a strong increase in necrotic cell death (but not in apoptosis). The mitochondrial O2 consumption increased gradually with decreasing pH. Conclusions These data show that acidic pHe in tumors plays an important role for gene expression independently from hypoxia. In parallel, acidosis modulates functional properties of tumors relevant for their malignant potential and which might be the result of pH-dependent gene expression.

scholarly journals Role of HMGB1 in apoptosis-mediated sepsis lethality

2006 ◽  
Vol 203 (7) ◽  
pp. 1637-1642 ◽  
Author(s):  
Shixin Qin ◽  
Haichao Wang ◽  
Renqi Yuan ◽  
Hui Li ◽  
Mahendar Ochani ◽  
...  
Keyword(s):  
Severe Sepsis ◽  
High Mobility ◽  
Organ Damage ◽  
The United States ◽  
Apoptotic Cells ◽  
Caspase Inhibitor ◽  
Common Pathway ◽  
The Third

Severe sepsis, a lethal syndrome after infection or injury, is the third leading cause of mortality in the United States. The pathogenesis of severe sepsis is characterized by organ damage and accumulation of apoptotic lymphocytes in the spleen, thymus, and other organs. To examine the potential causal relationships of apoptosis to organ damage, we administered Z-VAD-FMK, a broad-spectrum caspase inhibitor, to mice with sepsis. We found that Z-VAD-FMK–treated septic mice had decreased levels of high mobility group box 1 (HMGB1), a critical cytokine mediator of organ damage in severe sepsis, and suppressed apoptosis in the spleen and thymus. In vitro, apoptotic cells activate macrophages to release HMGB1. Monoclonal antibodies against HMGB1 conferred protection against organ damage but did not prevent the accumulation of apoptotic cells in the spleen. Thus, our data indicate that HMGB1 production is downstream of apoptosis on the final common pathway to organ damage in severe sepsis.

Retardation and Recovery of Growth in Brook Trout Fry (Salvelinus fontinalis) Exposed for Various Durations to Acidified Water

1986 ◽  
Vol 43 (10) ◽  
pp. 2048-2050 ◽  
Author(s):  
W. H. Tam ◽  
P. D. Payson ◽  
R. J. J. Roy
Keyword(s):  
Growth Inhibition ◽  
Growth Rates ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Low Ph ◽  
Fish Growth ◽  
Control Fish ◽  
Treated Fish ◽  
Test Fish ◽  
Neutral Water

Brook trout fry (Salvelinus fontinalis) were exposed to pH 4.66 for various durations up to 141 d and then returned to neutral water. Growth of test fish was in general significantly lower than that of control fish for exposures up to days 45–78. In four of six groups of acid-treated fish, growth eventually recovered and the growth rates were not different from that of control fish. The results suggested that growth inhibition was induced early in the exposure to sublethally low pH and that recovery in the latter phase of the experiment occurred whether pH remained acidic or was readjusted to neutral.

Lipidated Methotrexate Microbubbles: A Promising Rheumatoid Arthritis Theranostic Medicine Manipulated via Ultrasonic Irradiation

2021 ◽  
Vol 17 (7) ◽  
pp. 1293-1304
Author(s):  
Zhuofei Zhao ◽  
Xiaona Lin ◽  
Lulu Zhang ◽  
Xia Liu ◽  
Qingwen Wang ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
De Novo ◽  
Low Ph ◽  
Curative Effect ◽  
Inflammatory Microenvironment ◽  
Raw 264.7 Cell ◽  
Infection Focus ◽  
Raw 264.7 Cell Line

De novo designed lipidated methotrexate was synthesized and self-assembled into microbubbles for targeted rheumatoid arthritis theranostic treatment. Controlled lipidatedmethotrexate delivery was achieved by ultrasound-targetedmicrobubble destruction technique. Methotrexate was dissociated inflammatory microenvironment of synovial cavity, owing to representive low pH and enriched leucocyte esterase. We first manipulated methotrexate controlled release with RAW 264.7 cell line in vitro and further verified with rheumatoid arthritis rabbits in vivo. Results showed that lipidated methotrexate microbubbles precisely affected infection focus and significantly enhanced rheumatoid arthritis curative effect comparing with dissociative methotrexate. This study indicates that lipidated methotrexate microbubbles might be considered as a promising rheumatoid arthritis theranostics medicine.

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