Intracellular pH-temperature interactions of hepatocytes from American eels

1983 ◽  
Vol 245 (1) ◽  
pp. R32-R37
Author(s):  
P. J. Walsh ◽  
T. W. Moon
Keyword(s):  
Intracellular Ph ◽  
Acclimation Temperature ◽  
C Cells ◽  
Medium Ph ◽  
American Eel ◽  
Temperature Changes ◽  
American Eels ◽  
Temperature Interactions

The effects of acclimation temperature and acute temperature changes on the intracellular pH (pHi) of hepatocytes isolated from the American eel, Anguilla rostrata, were studied by the measurement of the distribution ratio of dimethyloxizolidinedione (DMO). Varying the concentration of DMO (10(-7) to 10(-4) M) did not affect estimates of pHi, indicating that DMO acts as an ideal pHi probe in eel hepatocytes. In vitro studies yielded values of liver cell pHi identical to those previously measured in vivo (in vitro pHi = 7.556 +/- 0.010; in vivo pHi = 7.570 +/- 0.049 at 20 degrees C); hepatocyte pHi varied inversely with acclimation temperature (5-20 degrees C) in a manner consistent with alphastat regulation (delta pH/delta T = -0.0182 +/- 0.021). During acute temperature increases (5-20 degrees C) and decreases (20-5 degrees C) hepatocytes regulated pHi to the appropriate (acclimated) value within 30-45 min posttransfer under conditions of constant medium pH (pHe). The effects of medium pH were also studied, and although patterns of pHi regulation differed between 5 and 20 degrees C cells, a pHi difference consistent with alphastat regulation was maintained between 5 and 20 degrees C cells over the pHe range 7.8-8.3.

Artificial maturation, fertilization, and early development of the American eel (Anguilla rostrata)

2010 ◽  
Vol 88 (11) ◽  
pp. 1121-1128 ◽  
Author(s):  
K. Oliveira ◽  
W. E. Hable
Keyword(s):  
Early Development ◽  
Anguilla Rostrata ◽  
Sargasso Sea ◽  
American Eel ◽  
Important Species ◽  
Vitro Fertilization ◽  
Commercially Important ◽  
Elusive Species ◽  
American Eels

Spawning for the American eel ( Anguilla rostrata (Le Sueur, 1817)) takes place in secretive locations within the Sargasso Sea, which has thus far prevented investigations of gametogenesis and early development in this ecologically and commercially important species. Attempts to induce maturation and reproduction in this species have been few and have produced limited results, with a single report of the production of gastrula-stage embryos. Here we report the successful maturation of female American eels. Maturation occurred within 13 weeks and ovulation was induced with a single injection of 17α,20β-dihydroxy-4-pregnen-3-one (DHP). Following in vitro fertilization, embryogenesis through hatching was observed and larvae were maintained for up to 6 days. We show that a crucial factor for successful fertilization is the stage of the oocyte at the time of induced ovulation. Oocytes that had not reached the migratory nucleus stage, or had passed this stage, were not successfully fertilized. These findings demonstrate that American eel can reproduce in the laboratory and previously untestable hypotheses pertaining to the developmental biology of this elusive species can now be explored.

Macrovascular dopamine release

1996 ◽  
Vol 270 (6) ◽  
pp. R1244-R1249
Author(s):  
S. Kraschinski ◽  
A. Epple ◽  
B. Nibbio
Keyword(s):  
Stress Responses ◽  
Dopamine Release ◽  
Vena Cava ◽  
Local Stress ◽  
American Eel ◽  
Cardinal Vein ◽  
Caudal Vein ◽  
Ventral Aorta

In an animal model, the American eel, perifused elastic arteries and large veins, but not the heart and organs with extensive microvascular supply (gills and opisthonephric kidney), release spontaneously free dopamine. Only the region of the cardinal vein, which contains the adrenomedullary equivalent, also releases norepinephrine (NE) and epinephrine (E). Ca2+, KCl, and E stimulate dopamine release from the ventral aorta and caudal vein, indicating that this phenomenon is due to secretion and not to washout. E also stimulates NE release from the ventral aorta and caudal vein. In the rat, both aorta and vena cava spontaneously release dopamine and NE. Thus dopamine secretion from large blood vessels may be general in vertebrates. The dopamine response to high physiological concentrations of E in vivo and in vitro suggests that macrovascular dopamine may be involved in local stress responses.

scholarly journals Anoikis Resistance as a Further Trait of Acidic-Adapted Melanoma Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Silvia Peppicelli ◽  
Jessica Ruzzolini ◽  
Francesca Bianchini ◽  
Elena Andreucci ◽  
Chiara Nediani ◽  
...  
Keyword(s):  
Blood Stream ◽  
Melanoma Cells ◽  
Extracellular Ph ◽  
Cloning Efficiency ◽  
Anoikis Resistance ◽  
Additional Mechanism ◽  
Medium Ph ◽  
Aggressive Cancer

Melanoma is characterized by a low extracellular pH, which contributes to the development of an aggressive phenotype characterized by several properties as the switch to an epithelial-to-mesenchymal program, the increase of apoptotic resistance, and the migratory ability together with the development of drug resistance. Here, we demonstrate that melanoma cells grown in low pH medium (pH 6.7) for a short (24 hours) or long (at least 3 months) period equally express an anoikis resistance profile. Anoikis is a form of apoptosis prompted by loss of adhesion, particularly requested by aggressive cancer cells to metastasize. Anoikis resistance was ascertained in acidic melanoma cells either grown in agarose-coated plates or incubated in rocking conditions. Both analyses indicate that acidic cells were more able to survive in a nonadherent condition than cells grown in standard pH, an effect resulting in a more cloning efficiency and migratory ability. Ability to survive during rocking was inhibited using mTOR/NF-kB inhibitors. Finally, we checked whether characteristics related to thein vitroanoikis resistance acquired by acidic melanoma cells might be also suitable forin vivochallenge. We injected acidic melanoma cells into blood stream, and then we verify how many cells survived in blood after 15 min from the injection. Only acidic cells, transient and chronic, survived, whereas melanoma cells grown in standard pH medium did not. Overall, we have had the opportunity to demonstrate that low extracellular pH represents an additional mechanism able to promote an anoikis resistance in solid tumors.

Improved in vivo tumor therapy via host–guest complexation

2016 ◽  
Vol 4 (15) ◽  
pp. 2691-2696 ◽  
Author(s):  
Yong Yao ◽  
Yang Wang ◽  
Ruibo Zhao ◽  
Li Shao ◽  
Ruikang Tang ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Drug Delivery System ◽  
Intracellular Ph ◽  
Tumor Therapy ◽  
Controlled Drug Delivery ◽  
Water Soluble ◽  
Ph Responsive ◽  
Mesoporous Nanoparticles

A decomposable and intracellular pH-responsive drug delivery system by immobilizing a water-soluble pillar[5]arene onto hollow mesoporous nanoparticles through host–guest complexation was successfully prepared and its application in controlled drug delivery in vitro and in vivo was also investigated.

scholarly journals Requirements for Germination of Clostridium sordellii Spores In Vitro

2009 ◽  
Vol 192 (2) ◽  
pp. 418-425 ◽  
Author(s):  
Norma Ramirez ◽  
Ernesto Abel-Santos
Keyword(s):  
Spore Germination ◽  
Reproductive Tract ◽  
Female Reproductive Tract ◽  
Binding Affinities ◽  
Temperature Changes ◽  
Clostridium Sordellii ◽  
Spore Activation ◽  
Ph Range

ABSTRACT Clostridium sordellii is a spore-forming, obligately anaerobic, Gram-positive bacterium that can cause toxic shock syndrome after gynecological procedures. Although the incidence of C. sordellii infection is low, it is fatal in most cases. Since spore germination is believed to be the first step in the establishment of Bacilli and Clostridia infections, we analyzed the requirements for C. sordellii spore germination in vitro. Our data showed that C. sordellii spores require three structurally different amino acids and bicarbonate for maximum germination. Unlike the case for Bacilli species, d-alanine had no effect on C. sordellii spore germination. C. sordellii spores germinated only in a narrow pH range between 5.7 and 6.5. In contrast, C. sordellii spore germination was significantly less sensitive to temperature changes than that of the Bacilli. The analysis of the kinetics of C. sordellii spore germination showed strong allosteric behavior in the binding of l-phenylalanine and l-alanine but not in that of bicarbonate or l-arginine. By comparing germinant apparent binding affinities to their known in vivo concentrations, we postulated a mechanism for differential C. sordellii spore activation in the female reproductive tract.

scholarly journals SUMOylation regulates nucleo-cytoplasmic shuttling of Elk-1

2004 ◽  
Vol 165 (6) ◽  
pp. 767-773 ◽  
Author(s):  
Sara Salinas ◽  
Anne Briançon-Marjollet ◽  
Guillaume Bossis ◽  
Marie-Aude Lopez ◽  
Marc Piechaczyk ◽  
...  
Keyword(s):  
Gene Activation ◽  
Early Gene ◽  
C Cells ◽  
Nuclear Target ◽  
Nuclear Retention ◽  
Extracellular Signals ◽  
Sumo Conjugation ◽  
Mitogen Activated Protein

The transcription factor Elk-1 is a nuclear target of mitogen-activated protein kinases and regulates immediate early gene activation by extracellular signals. We show that Elk-1 is also conjugated to SUMO on either lysines 230, 249, or 254. Mutation of all three sites is necessary to fully block SUMOylation in vitro and in vivo. This Elk-1 mutant, Elk-1(3R), shuttles more rapidly to nuclei of Balb/C cells fused to transfected HeLa cells. Coexpression of SUMO-1 or -2 strongly reduces shuttling by Elk-1 without affecting that of Elk-1(3R), indicating that SUMOylation regulates nuclear retention of Elk-1. Accordingly, overexpression of Elk-1(3R) in PC12 cells, where cytoplasmic relocalization of Elk-1 has been linked to differentiation, enhances neurite extension relative to Elk-1. The effect of Elk-1, but not of the 3R mutant, was blocked upon cotransfection with SUMO-1 or -2 and enhanced by coexpression with mutant Ubc-9. Thus, SUMO conjugation is a novel regulator of Elk-1 function through the control of its nuclear-cytoplasmic shuttling.

scholarly journals How to build a fast and highly sensitive sound detector that remains robust to temperature shifts

2019 ◽  
Author(s):  
Minghui Chen ◽  
Henrique von Gersdorff
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Auditory Information ◽  
Temperature Changes ◽  
Temporal Precision ◽  
Auditory Nerves ◽  
Afferent Fibers ◽  
Vesicle Exocytosis

AbstractFrogs must have sharp hearing abilities during the warm summer months to successfully find mating partners. This study aims to understand how frog hair cell ribbon-type synapses preserve both sensitivity and temporal precision during temperature changes. We performedin vitropatch-clamp recordings of hair cells and their afferent fibers in bullfrog amphibian papillae under room (23-25°C) and high (30-33°C) temperature. Afferent fibers exhibited a wide heterogeneity in membrane input resistance (Rin) from 100 MΩ to 1000 MΩ, which may contribute to variations in spike threshold and firing frequency. At higher temperatures, most fibers increased their frequency of action potential firing due to an increase in spontaneous EPSC frequencies. Hair cell resting membrane potential (Vrest) remained surprisingly stable during temperature increases, although both inward Ca2+current and outward K+current increased in amplitude. This increase in Ca2+current may explain the higher spontaneous EPSC frequencies. The larger “leak currents” at Vrestlowered Rinand produced higher electrical resonant frequencies. However, lower Rinshould decrease sensitivity to sound detection via smaller receptor potentials. Using membrane capacitance measurements, we suggest that hair cells can partially compensate for this reduced sensitivity by increasing exocytosis efficiency and the size of the readily releasable pool of synaptic vesicles. Furthermore, paired recordings of hair cells and their afferent fibers showed that synaptic delays become shorter and multivesicular release becomes more synchronous at higher temperatures, which should improve temporal precision. Altogether, our results explain many previousin vivoobservations on the temperature dependence of spikes in auditory nerves.Significance StatementThe vertebrate inner ear detects and transmits auditory information over a broad dynamic range of sound frequency and intensity. It achieves remarkable sensitivity to soft sounds and precise frequency selectivity. How does the ear of cold-blooded vertebrates maintain its performance level as temperature changes? More specifically, how does the hair cell to afferent fiber synapse in bullfrog amphibian papilla adjust to a wide range of physiological temperatures without losing its sensitivity and temporal fidelity to sound signals? This study usesin vitroexperiments to reveal the biophysical mechanisms that explain many observations made fromin vivoauditory nerve fiber recordings. We find that higher temperature facilitates vesicle exocytosis and electrical tuning to higher sound frequencies, which benefits sensitivity and selectivity.

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