Interactions among pyruvate concentration, pH, and Km of pyruvate in determining in vivo Q10 values of the lactate dehydrogenase reaction

1982 ◽  
Vol 60 (6) ◽  
pp. 1293-1299 ◽  
Author(s):  
Patrick J. Walsh ◽  
George N. Somero
Keyword(s):  
Lactate Dehydrogenase ◽  
Temperature Dependent ◽  
Temperature Changes ◽  
Gillichthys Mirabilis ◽  
Constant Ph ◽  
Dehydrogenase Reaction ◽  
Regulatory Capacity ◽  
Time Courses ◽  
Q10 Values

The interactions among pyruvate concentration, the apparent Michaelis constant (Km) of pyruvate, and intracellular pH on the Q10 of the lactate dehydrogenase (LDH) reaction of white skeletal muscle of the fish Gillichthys mirabilis were studied. Experimentally determined values for pyruvate concentration and Km of pyruvate (measured under both constant pH and variable (=biologically realistic) pH were used to estimate in vivo Q10's over acclimation time courses and in acute temperature-change situations. Temperature-dependent changes in pyruvate concentration were large. The 25 °C acclimated fish had approximately twice the pyruvate concentration of 15 °C acclimated specimens, and acute temperature changes also led to higher pyruvate levels at higher temperatures. These temperature-dependent changes in pyruvate concentration prevent temperature-dependent variation in the Km of pyruvate from having Q10-reducing influences. Rather, during acclimation a relatively stable ratio of Km: [substrate] is maintained. This is viewed as important for the preservation of correct regulatory capacity for the muscle LDH reaction.

scholarly journals Temperature and muscle

1985 ◽  
Vol 115 (1) ◽  
pp. 333-344 ◽  
Author(s):  
A. F. Bennett
Keyword(s):  
Mechanical Performance ◽  
Muscle Performance ◽  
Temperature Dependent ◽  
Thermal Dependence ◽  
Rate Processes ◽  
Behavioural Performance ◽  
Q10 Values ◽  
Contraction And Relaxation

Rates of force development, contraction and relaxation of vertebrate skeletal muscle are temperature dependent with Q10 values of approximately 2. Maximal forces developed have a low or negative thermal dependence. The functional basis of these patterns is poorly understood. Muscle performance generally does not acclimate. There appears to have been some evolutionary adaptation among species and classes to different thermal regimes, such that muscles from cold-adapted species maintain better mechanical performance at low temperatures than do those from warm-adapted animals. However, rate processes remain strongly thermally dependent even in animals with low or variable body temperatures. This thermal dependence of muscle in vitro is reflected in behavioural performance: maximal force generation in vivo is temperature independent and time-dependent activities are more rapid at higher muscle temperatures.

scholarly journals Impact of Moderate Temperature Changes on Neisseria meningitidis Adhesion Phenotypes and Proteome

2016 ◽  
Vol 84 (12) ◽  
pp. 3484-3495 ◽  
Author(s):  
Martin Lappann ◽  
Andreas Otto ◽  
Madita Brauer ◽  
Dörte Becher ◽  
Ulrich Vogel ◽  
...  
Keyword(s):  
Protein Expression ◽  
Neisseria Meningitidis ◽  
Outer Membrane ◽  
Biofilm Formation ◽  
Proteome Analysis ◽  
Ambient Air ◽  
Temperature Dependent ◽  
Content Type ◽  
Temperature Changes

Neisseria meningitidis , the meningococcus, bears the potential to cause life-threatening invasive diseases, but it usually colonizes the nasopharynx without causing any symptoms. Within the nasopharynx, Neisseria meningitidis must face temperature changes depending on the ambient air temperature. Indeed, the nasopharyngeal temperature can be substantially lower than 37°C, the temperature commonly used in experimental settings. Here, we compared the levels of meningococcal biofilm formation, autoaggregation, and cellular adherence at 32°C and 37°C and found a clear increase in all these phenotypes at 32°C suggestive of a stronger in vivo colonization capability at this temperature. A comparative proteome analysis approach revealed differential protein expression levels between 32°C and 37°C, predominantly affecting the bacterial envelope. A total of 375 proteins were detected. Use of database annotation or the PSORTb algorithm predicted 49 of those proteins to be localized in the outer membrane, 21 in either the inner or outer membrane, 35 in the periplasm, 56 in the inner membrane, and 208 in the cytosol; for 6 proteins, no annotation or prediction was available. Temperature-dependent regulation of protein expression was seen particularly in the periplasm as well as in the outer and inner membranes. N eisserial h eparin b inding a ntigen (NHBA), NMB1030, and adhesin complex protein (ACP) showed the strongest upregulation at 32°C and were partially responsible for the observed temperature-dependent phenotypes. Screening of different global regulators of Neisseria meningitidis suggested that the extracytoplasmic sigma factor σ E might be involved in temperature-dependent biofilm formation. In conclusion, subtle temperature changes trigger adaptation events promoting mucosal colonization by meningococci.

Thermal dependence of muscle function

1984 ◽  
Vol 247 (2) ◽  
pp. R217-R229 ◽  
Author(s):  
A. F. Bennett
Keyword(s):  
Fiber Type ◽  
Force Generation ◽  
Maximal Velocity ◽  
Body Temperatures ◽  
Temperature Dependent ◽  
Thermal Dependence ◽  
Mammalian Muscle ◽  
Rate Processes ◽  
Q10 Values

Maximal isometric forces during both twitch and tetanus are largely temperature independent in muscles from both endothermic and ectothermic vertebrates. Anuran muscle can develop maximal force at lower temperatures than mammalian muscle. Tetanic tension is maximal at normally experienced body temperatures in a variety of animals, but twitch tension seldom is. Thermal dependence of twitch tension varies with muscle fiber type: tension decreases with increasing temperature in fast-twitch muscles and remains constant in slow-twitch muscles. In contrast to the low temperature dependence of force generation, rates of development of tension (time to peak twitch tension and tetanic rise time) and maximal velocity of shortening and power output are markedly temperature dependent, with average temperature coefficient (Q10) values of 2.0-2.5 Q10 values for rate processes of anuran muscle are only slightly lower than those of mammalian muscle. High body temperatures permit rapid rates of muscle contraction; animals active at low body temperatures do not achieve the maximal rate performance their muscles are capable of delivering. Thermal acclimation or hibernation does not appear to result in compensatory adjustments in either force generation or rate processes. In vivo, dynamic processes dependent on contractile rates are positively temperature dependent, although with markedly lower Q10 values than those of isolated muscle. Static force application in vivo is nearly temperature independent.

Temperature-Dependent Photoluminescence Spectra of PbSe Quantum Dots for Temperature Markers

2012 ◽  
Vol 482-484 ◽  
pp. 2547-2550
Author(s):  
Peng Fei Gu ◽  
Ya Nan Wang ◽  
Jia Jia Cao ◽  
Yu Yan ◽  
Tie Qiang Zhang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Temperature Sensitivity ◽  
Peak Position ◽  
Strong Temperature Dependence ◽  
Photoluminescence Spectra ◽  
Temperature Dependent ◽  
Temperature Variations ◽  
Temperature Changes ◽  
Optical Readout ◽  
Temperature Dependent Photoluminescence

We here report the temperature effect on photoluminescence(PL) spectra of PbSe quantum dots (QDs), which exhibit a strong temperature dependence on their spectra position and intensity. They potentially act as the temperature marker, sensing temperature variations and reporting temperature changes remotely through optical readout. In addition, the temperature sensitivity characterized by peak position of PbSe QDs was found to be 0.39nm/°C in a range of 10-100 °C.

Role of ion transfer processes in acid-base regulation with temperature changes in fish

1984 ◽  
Vol 246 (4) ◽  
pp. R441-R451 ◽  
Author(s):  
N. Heisler
Keyword(s):  
Ion Transfer ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Fish Tissues ◽  
Model Calculations ◽  
Temperature Changes ◽  
Transfer Processes ◽  
Transfer Mechanisms

The contributions of transmembrane and transepithelial ion transfer processes and of nonbicarbonate buffering to the in vivo acid-base regulation have been evaluated. Model calculations were performed utilizing experimental data on transepithelial transfer of ions relevant for the acid-base regulation, the intracellular buffering properties of fish tissues, and the behavior of intracellular and extracellular pH and bicarbonate concentration with changes of temperature. The results of these studies indicate that the changes in the pK values of physiological nonbicarbonate buffers with changes in temperature support the adjustment of pH to lower values with rising temperature; however, transmembrane and transepithelial ion transfer mechanisms determine the acid-base regulation of intracellular and extracellular compartments.

Control of glycolysis in vertebrate skeletal muscle during exercise

1996 ◽  
Vol 270 (4) ◽  
pp. R821-R829 ◽  
Author(s):  
U. Krause ◽  
G. Wegener
Keyword(s):  
Gastrocnemius Muscle ◽  
Rana Temporaria ◽  
High Capacity ◽  
Repeated Exercise ◽  
Frog Rana Temporaria ◽  
Time Courses ◽  
Fructose 1,6 Bisphosphate ◽  
Assay Conditions

The gastrocnemius muscle of the frog (Rana temporaria) has a high capacity for anaerobic glycolysis from glycogen. Glycolytic metabolites and effectors of phosphofructokinase, particularly the hexose bisphosphates, were followed in muscle during exercise (swimming between 5 s and 5 min), recovery (rest for up to 2 h after 5 min of swimming), and repeated exercise (swimming for up to 60 s after 2 h of recovery). Glycogen phosphorylase and phosphofructokinase were swiftly activated with exercise. The hexose bisphosphates followed markedly different time courses. Fructose 1,6-bisphosphate was transiently increased in both exercise and repeated exercise. This appears to be an effect rather than a cause of phosphofructokinase activation. Glucose 1,6-biphosphate was accumulated only while phosphofructokinase was active and was unchanged at other times. Fructose 2,6-biphosphate showed a 10-fold transient increase on exercise in rested frogs, almost disappeared from the muscle during recovery, and did not change during repeated exercise. Fructose 2,6-biphosphate is a potent activator of phosphofructokinase in vitro under near physiological assay conditions, and it may serve this function also in vivo during exercise. Glucose 1,6-biphosphate could be an activator of phosphofructokinase in repeated exercise when fructose 2,6-biphosphate is not available.

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.

scholarly journals ATP:Mg2+ shapes condensate properties of rRNA-NPM1 in vitro nucleolus model and its partitioning of ribosomes

2021 ◽  
Author(s):  
N. Amy Yewdall ◽  
Alain A. M. André ◽  
Merlijn H. I. van Haren ◽  
Frank H. T. Nelissen ◽  
Aafke Jonker ◽  
...  
Keyword(s):  
Ribosomal Rna ◽  
Enzymatic Reaction ◽  
Atp Depletion ◽  
Gel Point ◽  
Dependent Manner ◽  
Biophysical Properties ◽  
Temperature Dependent ◽  
Quantitative Fluorescence

Nucleoli have viscoelastic gel-like condensate dynamics that are not well represented in vitro. Nucleoli models, such as those formed by nucleophosmin 1 (NPM1) and ribosomal RNA (rRNA), exhibit condensate dynamics orders of magnitude faster than in vivo nucleoli. Here we show that an interplay between magnesium ions (Mg2+) and ATP governs rRNA dynamics, and this ultimately shapes the physical state of these condensates. Using quantitative fluorescence microscopy, we demonstrate that increased RNA compaction occurs in the condensates at high Mg2+ concentrations, contributing to the slowed RNA dynamics. At Mg2+ concentrations above 7 mM, rRNA is fully arrested and the condensates are gels. Below the critical gel point, NPM1-rRNA droplets age in a temperature-dependent manner, suggesting that condensates are viscoelastic materials, undergoing maturation driven by weak multivalent interactions. ATP addition reverses the dynamic arrest of rRNA, resulting in liquefaction of these gel-like structures. Surprisingly, ATP and Mg2+ both act to increase partitioning of NPM1-proteins as well as rRNA, which influences the partitioning of small client molecules. By contrast, larger ribosomes form a halo around NPM1-rRNA coacervates when Mg2+ concentrations are higher than ATP concentrations. Within cells, ATP levels fluctuate due to biomolecular reactions, and we demonstrate that a dissipative enzymatic reaction can control the biophysical properties of in vitro condensates through depletion of ATP. This enzymatic ATP depletion also reverses the formation of the ribosome halos. Our results illustrate how cells, by changing local ATP concentrations, may regulate the state and client partitioning of RNA-containing condensates such as the nucleolus.

scholarly journals Mutations affecting the tRNA-splicing endonuclease activity of Saccharomyces cerevisiae.

Genetics ◽  
1988 ◽  
Vol 118 (4) ◽  
pp. 609-617
Author(s):  
M Winey ◽  
M R Culbertson
Keyword(s):  
Growth Defect ◽  
Temperature Sensitive ◽  
Gene Products ◽  
Endonuclease Activity ◽  
Temperature Dependent ◽  
Direct Role ◽  
Trna Splicing

Abstract Two unlinked mutations that alter the enzyme activity of tRNA-splicing endonuclease have been identified in yeast. The sen1-1 mutation, which maps on chromosome 12, causes temperature-sensitive growth, reduced in vitro endonuclease activity, and in vivo accumulation of unspliced pre-tRNAs. The sen2-1 mutation does not confer a detectable growth defect, but causes a temperature-dependent reduction of in vitro endonuclease activity. Pre-tRNAs do not accumulate in sen2-1 strains. The in vitro enzyme activities of sen1-1 and sen2-1 complement in extracts from a heterozygous diploid, but fail to complement in mixed extracts from separate sen1-1 and sen2-1 haploid strains. These results suggest a direct role for SEN gene products in the enzymatic removal of introns from tRNA that is distinct from the role of other products known to affect tRNA splicing.

scholarly journals In Vivo Enzymes Activities of Some Ru(II) Compounds with N-Alkylphenothiazines

2016 ◽  
Vol 66 (4) ◽  
pp. 497-508
Author(s):  
P. Milena Krstić ◽  
Z. Sunčica Borozan ◽  
P. Sofija Sovilj ◽  
R. Sanja Grgurić-Šipka ◽  
M. Jelena Oljarević
Keyword(s):  
Antioxidant Activity ◽  
Enzyme Activity ◽  
Lactate Dehydrogenase ◽  
Normal Activity ◽  
Protective Effects ◽  
Toxic Compounds ◽  
Physiological Conditions ◽  
Positive Effects ◽  
Ldh Activity

Abstract The purpose of the present study was to investigate and compare the effects of two ruthenium complexes with trifluoperazine on acethylcholinesterase enzyme activity and lactate dehydrogenase levels in vivo under physiological conditions in rats blood. Complexes 1 and 2 showed positive effects on acethylcholinesterase at all doses and did not disturb its normal activity. Total LDH activity was inhibited in the presence of both complexes, but Ru(II) complexes showed different effects on the activity of LDH isoenzymes. The activities of LDH1 and LDH2 isoenzymes were decreased in all applied doses of the complex 2, while the activity of LDH2 reduced using complex 1 in the same doses. Results of the present study suggest the neuro- and cardio protective potential of oral administration of complexes 1 and 2, as non-toxic compounds under physiological conditions. These protective effects are the result of their potent antioxidant activity.

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