Oxygen dependence of redox state of copper in cytochrome oxidase in vitro

1993 ◽  
Vol 74 (4) ◽  
pp. 1622-1627 ◽  
Author(s):  
Y. Hoshi ◽  
O. Hazeki ◽  
M. Tamura
Keyword(s):  
Respiratory Rate ◽  
Cytochrome Oxidase ◽  
Near Infrared ◽  
Energy State ◽  
Oxygen Affinity ◽  
Quantitative Information ◽  
Low Oxygen ◽  
Straight Line ◽  
Oxygen Concentrations

To obtain quantitative information about tissue oxygenation from near-infrared signals, the oxygen dependencies of the redox states of both heme a+a3 and copper in cytochrome oxidase of isolated mitochondria were determined at low oxygen concentrations (10(-6)-10(-9) M) using leghemoglobin as an oxygen indicator. The maximum absorbance changes caused by the aerobic-anaerobic transition measured at 830–760 nm of copper in state 3, state 4, and the uncoupled state were 10, 17, and 5% of those at 605–620 nm of heme a+a3, respectively. Thus the relative absorbance ratio of copper to heme a+a3 could be used as a sensitive indicator for the mitochondrial energy state. The oxygen concentrations required for the half-maximal reduction of heme a+a3 varied with the energy state and the respiratory rate and were 7.8 x 10(-8) and 1.6 x 10(-7) M in state 4 and state 3, respectively. In contrast, that of copper was 7.5 x 10(-8) M and was independent of both the energy state and the respiratory rate. The relationship between the percent oxidation of heme a+a3 and copper in the aerobic-anaerobic transition did not show a straight-line relationship. This was referred to as the difference in oxygen affinity between these two chromophores. The deviation from the straight line was larger in state 3 than in state 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of oxygen concentrations on developmental competence and transcriptomic profile of yak oocytes

Zygote ◽  
2020 ◽  
Vol 28 (6) ◽  
pp. 459-469
Author(s):  
Ruizhe Li ◽  
Yuzhu Luo ◽  
Jingtao Xu ◽  
Yonggang Sun ◽  
Zhijie Ma ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Enrichment Analysis ◽  
Oocyte Quality ◽  
Signalling Pathway ◽  
Developmental Competence ◽  
Low Oxygen ◽  
Transcriptomic Profile ◽  
Low Oxygen Concentration ◽  
Oxygen Concentrations

SummaryOxygen concentration influences oocyte quality and subsequent embryo development, but it remains unclear whether oxygen concentrations affect the developmental competence and transcriptomic profile of yak oocytes. In this study, we investigated the effects of different oxygen concentrations (5% versus 20%) on the developmental competence, reactive oxygen species (ROS) levels, glutathione (GSH) content, and transcriptomic profile of yak oocytes. The results showed that a low oxygen concentration significantly increased the maturation rate of yak oocytes (81.2 ± 2.2% vs 75.9 ± 1.3%) and the blastocyst quality of yak in vitro fertilized embryos. Analysis of ROS and GSH showed that a low oxygen concentration reduced ROS levels and increased the content of GSH (75.05 ± 7.1 ng/oocyte vs 50.63 ± 5.6 ng/oocyte). Furthermore, transcriptomic analysis identified 120 differentially expressed genes (DEGs) between the two groups of oocytes. Gene enrichment analysis of the DEGs indicated multiple cellular processes, including oxidative phosphorylation, transcription regulation, mitochondrial regulation, oestrogen signalling pathway, HIF-1 signalling pathway, TNF signalling pathway, were involved in the response to oxygen concentration alterations. Taken together, these results indicated that a low oxygen concentration improved the developmental competence of yak oocytes.

Controlling matrix formation and cross-linking by hypoxia in cardiovascular tissue engineering

2010 ◽  
Vol 109 (5) ◽  
pp. 1483-1491 ◽  
Author(s):  
Marijke A. A. van Vlimmeren ◽  
Anita Driessen-Mol ◽  
Marloes van den Broek ◽  
Carlijn V. C. Bouten ◽  
Frank P. T. Baaijens
Keyword(s):  
Gene Expression ◽  
Tissue Engineering ◽  
Tissue Development ◽  
Low Oxygen ◽  
Cardiovascular Tissue ◽  
Expression Levels ◽  
Cardiovascular Tissue Engineering ◽  
Gene Expression Levels ◽  
Oxygen Concentrations

In vivo functionality of cardiovascular tissue engineered constructs requires in vitro control of tissue development to obtain a well developed extracellular matrix (ECM). We hypothesize that ECM formation and maturation is stimulated by culturing at low oxygen concentrations. Gene expression levels of monolayers of human vascular-derived myofibroblasts, exposed to 7, 4, 2, 1, and 0.5% O2( n = 9 per group) for 24 h, were measured for vascular endothelial growth factor (VEGF), procollagen α1(I) and α1(III), elastin, and cross-link enzymes lysyl oxidase (LOX) and lysyl hydroxylase 2 (LH2). After 4 days of exposure to 7, 2, and 0.5% O2( n = 3 per group), protein synthesis was evaluated. All analyses were compared with control cultures at 21% O2. Human myofibroblasts turned to hypoxia-driven gene expression, indicated by VEGF expression, at oxygen concentrations of 4% and lower. Gene expression levels of procollagen α1(I) and α1(III) increased to 138 ± 26 and 143 ± 19%, respectively, for all oxygen concentrations below 4%. At 2% O2, LH2 and LOX gene expression levels were higher than control cultures (340 ± 53 and 136 ± 29%, respectively), and these levels increased even further with decreasing oxygen concentrations (611 ± 176 and 228 ± 45%, respectively, at 0.5% O2). Elastin gene expression levels remained unaffected. Collagen synthesis and LH2 protein levels increased at oxygen concentrations of 2% and lower. Oxygen concentrations below 4% induce enhanced ECM production by human myofibroblasts. Implementation of these results in cardiovascular tissue engineering approaches enables in vitro control of tissue development.

scholarly journals Radiative and Non-Radiative Decay Pathways in Carbon Nanodots toward Bioimaging and Photodynamic Therapy

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 70
Author(s):  
Yujin Kim ◽  
Yoonsang Park ◽  
Seulgi Han ◽  
Wonchan Park ◽  
Mungu Kim ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Radiative Decay ◽  
Near Infrared ◽  
Energy State ◽  
Carbon Nanodots ◽  
Ros Generation ◽  
Trap States ◽  
Different Types ◽  
Energy States

The origin and classification of energy states, as well as the electronic transitions and energy transfers associated with them, have been recognized as critical factors for understanding the optical properties of carbon nanodots (CNDs). Herein, we report the synthesis of CNDs in an optimized process that allows low-temperature carbonization using ethanolamine as the major precursor and citric acid as an additive. The results obtained herein suggest that the energy states in our CNDs can be classified into four different types based on their chemical origin: carbogenic core states, surface defective states, molecular emissive states, and non-radiative trap states. Each energy state is associated with the occurrence of different types of emissions in the visible to near-infrared (NIR) range and the generation of reactive oxygen species (ROS). The potential pathways of radiative/non-radiative transitions in CNDs have been systematically studied using visible-to-NIR emission spectroscopy and fluorescence decay measurements. Furthermore, the bright photoluminescence and ROS generation of these CNDs render them suitable for in vitro imaging and photodynamic therapy applications. We believe that these new insights into the energy states of CNDs will result in significant improvements in other applications, such as photocatalysis and optoelectronics.

scholarly journals HYPOXIA AND REPRODUCTIVE HEALTH: Oxygen and development of the human placenta

Reproduction ◽  
2021 ◽  
Vol 161 (1) ◽  
pp. F53-F65 ◽  
Author(s):  
Graham J Burton ◽  
Tereza Cindrova-Davies ◽  
Hong wa Yung ◽  
Eric Jauniaux
Keyword(s):  
Oxidative Stress ◽  
Human Placenta ◽  
Epithelial Mesenchymal Transition ◽  
First Trimester ◽  
Extravillous Trophoblast ◽  
Low Oxygen ◽  
Placental Development ◽  
Mesenchymal Transition ◽  
Oxygen Concentrations

Development of the human placenta takes place in contrasting oxygen concentrations at different stages of gestation, from ~20 mmHg during the first trimester rising to ~60 mmHg at the start of the second trimester before gradually declining to ~40 mmHg at term. In view of these changes, the early placenta has been described as ‘hypoxic’. However, placental metabolism is heavily glycolytic, supported by the rich supply of glucose from the endometrial glands, and there is no evidence of energy compromise. On the contrary, the trophoblast is highly proliferative, with the physiological low-oxygen environment promoting maintenance of stemness in progenitor populations. These conditions favour the formation of the cytotrophoblastic shell that encapsulates the conceptus and interfaces with the endometrium. Extravillous trophoblast cells on the outer surface of the shell undergo an epithelial-mesenchymal transition and acquire invasive potential. Experimental evidence suggests that these changes may be mediated by the higher oxygen concentration present within the placental bed. Interpreting in vitro data is often difficult, however, due to the use of non-physiological oxygen concentrations and trophoblast-like cell lines or explant models. Trophoblast is more vulnerable to hyperoxia or fluctuating levels of oxygen than to hypoxia, and some degree of placental oxidative stress likely occurs in all pregnancies towards term. In complications of pregnancy, such as early-onset pre-eclampsia, malperfusion generates high levels of oxidative stress, causing release of factors that precipitate the maternal syndrome. Further experiments are required using genuine trophoblast progenitor cells and physiological concentrations to fully elucidate the pathways by which oxygen regulates placental development.

Redox behavior of cytochrome oxidase in the rat brain measured by near-infrared spectroscopy

1997 ◽  
Vol 83 (6) ◽  
pp. 1842-1848 ◽  
Author(s):  
Yoko Hoshi ◽  
Osamu Hazeki ◽  
Yasuyuki Kakihana ◽  
Mamoru Tamura
Keyword(s):  
Infrared Spectroscopy ◽  
Rat Brain ◽  
Cytochrome Oxidase ◽  
Near Infrared Spectroscopy ◽  
Oxygen Delivery ◽  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Redox Behavior ◽  
Hypoxic Conditions

Hoshi, Yoko, Osamu Hazeki, Yasuyuki Kakihana, and Mamoru Tamura. Redox behavior of cytochrome oxidase in the rat brain measured by near-infrared spectroscopy. J. Appl. Physiol. 83(6): 1842–1848, 1997.—Using near-infrared spectroscopy, we developed a new approach for measuring the redox state of cytochrome oxidase in the brain under normal blood-circulation conditions. Our algorithm does not require the absorption coefficient of cytochrome oxidase, which differs from study to study. We employed this method for evaluation of effects of changes in oxygen delivery on cerebral oxygenation in rats. When fractional inspired oxygen was decreased in a stepwise manner from 100 to <10%, at which point the concentration of oxygenated hemoglobin ([HbO2]) decreased by ∼60%, cytochrome oxidase started to be reduced. Increases in arterial [Formula: see text] under hyperoxic conditions caused an increase in [HbO2], whereas further oxidation of cytochrome oxidase was not observed. The dissociation of the responses of hemogloblin and cytochrome oxidase was also clearly observed after the injection of epinephrine under severely hypoxic conditions; that is, cytochrome oxidase was reoxidized with increasing blood pressure, whereas hemoglobin oxygenation was not changed. These data indicated that oxygen-dependent redox changes in cytochrome oxidase occur only when oxygen delivery is extremely impaired. This is consistent with the in vitro data of our previous study.

Energy-dependent redox state of hemea +a 3 and copper of cytochrome oxidase in perfused rat brain in situ

1998 ◽  
Vol 275 (4) ◽  
pp. C1022-C1030 ◽  
Author(s):  
Akira Matsunaga ◽  
Yasutomo Nomura ◽  
Satoshi Kuroda ◽  
Mamoru Tamura ◽  
Jun Nishihira ◽  
...  
Keyword(s):  
Rat Brain ◽  
Cytochrome Oxidase ◽  
Time Course ◽  
Near Infrared ◽  
Control Level ◽  
Oxygen Affinity ◽  
Global Ischemia ◽  
Slow Phase ◽  
Redox Behavior ◽  
Rapid Phase

Using the blood-free perfused rat brain, we examined the redox behavior of cytochrome oxidase of two chromophores, heme a + a 3 and copper. When perfusate inflow was stopped to induce global ischemia, the reduction of heme a + a 3 was triphasic, with a rapid phase, a slow phase, and a second rapid phase. In contrast, the reduction of copper was monophasic after the rapid phase of heme a + a 3. The triphasic reduction of heme a + a 3 was diminished by energy-depleting treatments, such as addition of an uncoupler. The time course of the reduction of copper was not affected by the energy depletion. During global ischemia the decrease in creatine phosphate nearly paralleled the reduction of heme a + a 3, whereas ATP remained at the control level until ∼60% of heme a + a 3 was reduced in the rapid phase. In the slow phase, ATP started to decrease with the reduction of copper. The redox behavior of copper was similar to the slow phase of the reduction of heme a+ a 3 because of the higher oxygen affinity of copper than of heme a + a 3. Therefore, the rapid phase of the reduction of heme a + a 3 can be used as an alarm before a decrease in ATP, whereas the reduction of copper indicates a decrease in ATP under severe hypoxia. Thus the copper signal in noninvasive near-infrared spectroscopy is a useful parameter for the clinical setting.

Effects of oxygen concentration on the metabolism of

1989 ◽  
Vol 1 (2) ◽  
pp. 99 ◽  
Author(s):  
NK Khurana ◽  
RG Wales
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Concentration ◽  
Glycogen Content ◽  
Carbon Dioxide Production ◽  
Morphological Development ◽  
Low Oxygen ◽  
Beneficial Effects ◽  
Low Oxygen Concentration ◽  
Oxygen Concentrations

The utilization of the acid-soluble glycogen pool in pulse-labelled embryos was significantly enhanced during 24- and 48-h chase culture under low oxygen concentrations of 5, 2.5 and 1%. The lower the oxygen tension the greater was the turnover in the pool. The morphological development of embryos was equally as good at very low oxygen concentrations as when embryos were cultured in 5-20% oxygen. Reduction in oxygen concentration enhanced the oxidative utilization of substrate, as measured by rate of carbon dioxide production. The present study could provide an explanation for the discrepancy in glycogen content between mouse blastocysts developing in utero and in vitro and for the reported beneficial effects of low oxygen concentration during development of embryos in culture.

Respiration and Adaptation to the Terrestrial Habitat in the Land Hermit Crab Coenobita Clypeatus

1979 ◽  
Vol 79 (1) ◽  
pp. 265-281
Author(s):  
BRIAN R. McMAHON ◽  
WARREN W. BURGGREN
Keyword(s):  
Oxygen Content ◽  
Oxygen Affinity ◽  
Low Oxygen ◽  
Land Crabs ◽  
Terrestrial Habitats ◽  
Simulated Rain ◽  
Oxygen Tensions ◽  
Saturated Oxygen

The frequencies of heart (fH) and scaphognathite (ventilatory = fBC) pumping, and responses to hypoxia, hypercapnia and wetting (simulated rain), as well as oxygen consumption (MOO2), pre- and postbranchial haemolymph oxygen tension (POO2), oxygen content (COO2), carbon dioxide content (CCOCO2) and pH were measured in adult land crabs Coenobita clypeatus. There was a large increase in f8C in response to both hypoxia and wetting but a smaller increase in response to even severe hypercapnia. Some evidence suggests that ventilation via the scaphognathites may have been supplemented by a second (branchiostegal) pump when ventilatory requirement was high. fH was less responsive to either hypoxia or hypercapnia, but decreased with severe exposure to either. Haemolymph oxygen tensions were low (Pα,Oα,O2 = 14, PvOvO2 = 8) but haemocyanin oxygen affinity was high in vivo (P50 = 10 torr at 23°C) and postbranchial haemocyanin was 60–80% saturated. Oxygen content was also high allowing adequate oxygen release to the tissues despite the low oxygen tensions. ΔP50/Δt = 0.37 torr/Δ °C, log ΔP50/ΔpH = - 0.84 torr/pH unit, both determined in vitro were lower than literature values for marine and littoral species. As in other terrestrial species, CCOCO2 and PCOCO2, (calculated) were high, as were both bicarbonate and non-bicarbonate buffering capacities. Water loss was less (0–08% body weight. h−1) in Coenobita than in other terrestrial crustaceans, this resulting from the protection of the adopted shell. Results obtained from Coenobita are compared with those from other terrestrial and littoral crabs to illustrate the influence of the adopted shell on the degree of modification needed to enter terrestrial habitats.

pH and haemoglobin oxygen affinity in blood from the Antarctic cod Dissostichus mawsoni

1977 ◽  
Vol 67 (1) ◽  
pp. 77-88
Author(s):  
J. Qvist ◽  
R. E. Weber ◽  
A. L. DeVries ◽  
W. M. Zapol
Keyword(s):  
Molecular Mechanisms ◽  
Oxygen Affinity ◽  
Oxygen Binding ◽  
Low Oxygen ◽  
Binding Properties ◽  
Dissostichus Mawsoni ◽  
Blood Ph ◽  
The Antarctic ◽  
Low Oxygen Affinity

Blood pH in the antarctic cod (Dissostichus mawsoni) and in two Trematomus species, occlrring at --1-9 degrees C, is extremely high (approximately 8-2 to 8-3). This supports and extends Rahn's (1966) model for the temperature-pH relationship in cold-blooded vertebrates. The blood of D. mawsoni shows a low oxygen affinity (P50 approximately equal to 14-5 mmHg at pH 8–16 and −1-9 degrees C). Despite normal in vitro temperature and pH sensitivities, blood P50 increases only slightly when live fish are temperature-stressed (+ 4-0 degrees C), or become acidotic as a result of agitational stress (blood pH 7–71), primarily as a result of compensatory decreases in blood ATP levels. Oxygen-binding properties of ‘stripped’ (cofactor-free) solutions of D. mawsoni haemoglobin were measured in attempts to elucidate the molecular mechanisms involved in the function of the pigment.

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