Influence Of Anoxia Research Articles

The trace fossil record of the Toarcian Oceanic Anoxic Event in the Iberian Massif

Trace fossil (ichnological) analysis of the Toarcian Oceanic Anoxic Event (T‐OAE) in several sections from the Iberian Massif reveals a comparatively minor incidence of this global anoxic event in the macrobenthic trace maker community. A variable trace fossil record can be recognized, involving changes in ichnodiversity, abundance and size of structures, evidencing not extinctions, but the effects of the event on the behaviour, palaeoecology and palaeobiology of trace makers. However, the influence of anoxia is only partially identified, with other palaeoenvironmental conditions—nutrient availability and substrate features, among others—being the major parameters influencing the trace maker community during the T‐OAE.

The influence of anoxia and substrate availability on N2O cycling by denitrification in the upper boundary of the oxygen minimum zone off northern Chile

The influence of anoxia and substrate availability on N₂O cycling by denitrification in the upper boundary of the oxygen minimum zone off northern Chile

NO- and H2S brain systems of the Japanese shore crab Hemigrapsus sanguineus under conditions of anoxia

The topography and dynamics of the activity of the enzymes of the synthesis of nitric oxide (NO) and hydrogen sulfide (H2S) in the brain of the Japanese shore crab Hemigrapsus sanguineus after 1, 6, and 12 h ofanoxia was studied histochemically and immunocytochemically. Changes in the activity and number of NO- and CBS-immune-positive cells that take place due to anoxia and the intensity of which depends on the duration of the influence were revealed. The fact that the balance between the nitric oxide and hydrogen sulfide systems in the brain of the crabs H. sanguineus is preserved indicates the joint participation of those systems in the central regulation of adaptive mechanisms under the influence of anoxia and, apparently, plays an important role in the adaptation of these hydrobionts to oxygen deficit.

Intracellular pH in rice and wheat root tips under hypoxic and anoxic conditions

The influence of anoxia and hypoxia on dynamic of intracellurar pH and ATP content in rice and wheat root tips was investigated with 31P-NMR spectroscopy. Both cereals responded to hypoxia similarly, by rapid cytoplasmic acidification (from pH 7.6-7.7 to 7.1), which was followed by slow partial recovery (0.3 units). Anoxia led to a dramatic pHcyt drop in tissues of both species (from pH 7.6-7.7 to less than 7.0) and partial recovery took place in rice only. In wheat, the acidification continued to pH 6.8 after 6 h of exposure. Anoxic wheat root tips were deficient in ADH induction, whereas increased activity of alcoholic fermentation enzymes took place in anoxic rice root tips, as well as in both species after hypoxic treatment. In both plants, NTP content followed the dynamics of pHcyt. There was a strong correlation between NTP content and cytoplasmic H+ activity ([H+]cyt = 10–pHcyt) for both hypoxic and anoxic conditions. In this addendum we want to focus the reader’s attention on the importance of adequate experimental design when hypoxia is under investigation and on some further perspectives of intracellular pH regulation in plants under anaerobic conditions.

IGF-I activates PKB and prevents anoxic apoptosis in Achilles tendon cells

Anoxia and apoptosis are both implicated in chronic tendon pathology, however the influence of anoxia on the viability of tendon cells is not known. The objectives of the current study were to (i) investigate the effect of oxygen withdrawal on the viability of porcine Achilles tendon cells (ATCs), and (ii) examine the ability of IGF-I, a factor with known regenerative properties in tendon, to prevent ATC death. Cultured ATCs were enclosed in an anaerobic chamber. The mechanism of cell death was examined by flow cytometry of ATCs double labeled with Annexin-V and propidium iodide (PI). Caspase activity was determined by a fluorometric assay, and nuclear morphology was examined by Hoechst staining. The cell death induced by anoxia was time-dependent, and was characterized by phosphatidylserine exposure on the outer membrane, caspase activation and DNA fragmentation. Death was inhibited by the addition of IGF-I in a dose-dependent manner. The ability of IGF-I to activate the pro-survival PKB pathway in ATCs was inhibited by LY294002, indicating the importance of PI3K in the response of ATCs to IGF-I. These data suggest that cell death induced by lack of oxygen is predominantly apoptotic and can be prevented by pro-survival IGF-I signaling. This mechanism may contribute to the beneficial effect of IGF-I on tendon.

Influence of anoxia on the induction of mutations by phenylalanine radicals during γ-irradiation of plasmid DNA in aqueous solution

When DNA is irradiated in aqueous solution, most of the damage is inflicted by water-derived radicals. This is called the indirect effect of ionizing radiation. However in whole cells not only the primary formed water radicals play a role, because some cellular compounds form secondary radicals which can also damage DNA. It is known that the amino acid phenylalanine is able to react with water radicals, resulting in the production of secondary phenylalanine radicals which can damage and inactivate DNA. In a previous study the influence of the presence of phenylalanine during γ-irradiation of DNA in aqueous solution under oxic conditions was studied. Under anoxic irradiation conditions different amounts and types of reactive water-derived radicals are formed compared to oxic conditions and also different phenylalanine radicals are formed. Therefore, this study examines the influence of the presence of phenylalanine under anoxic conditions on the γ-radiation-induced mutation spectrum. The results indicate that phenylalanine radicals are damaging to DNA, but less effective compared to primary water radicals. On the mutational level, in the presence of phenylalanine radicals under anoxic conditions, the amount of mutations on G:C base pairs was significantly decreased as compared to oxic conditions. Furthermore, the results of this study indicate that nucleotide excision repair is involved in repair of both inactivating and mutagenic damage induced by phenylalanine radicals under anoxic conditions.

Influence of anoxia on sprouting of vegetative propagules of three species of aquatic plant propagules

Vegetative propagules ofPotamogeton pectinatus, P. gramineus, andHydrilla verticillata were exposed to aerobic or anaerobic atmospheres for 7, 14, or 21 days in the dark at 18°C or 7°C. There were no differences in the proportion of propagules sprouting due the presence or absence of oxygen. However, propagules exposed to an anaerobic atmosphere at 18°C sprouted sooner than those exposed to an aerobic atmosphere. This effect was less apparent when exposure to anaerobic conditions was at 7°C. In field experiments,Potamogeton gramineus winter buds were buried at 4 depths in Byrnes Canal sediment. Those buried for 25 days at 25 cm (where sediment redox potential is < 50 mV and conditions are likely hypoxic) showed discoloration consistent with sulfide deposition, and they sprouted more rapidly than winter buds buried at 5 or 15 cm. As the duration of burial in Byrnes Canal sediment increased, propagule sprouting time decreased. Predicting the timing of propagule sprouting in habitats with fluctuating water levels may benefit from information on seasonal changes in the oxygen status of the sediments.

The Influence of Anoxia on Plants of Saline Habitats with Special Reference to the Sulphur Cycle

Plants of saline habitats can encounter anoxic conditions to extents which vary with habitat and life form. Rhizophytes (with roots or rhizoids in a sediment) routinely have anoxia or hypoxia in their roots, rhizoids and rhizomes. Haptophytes (attached to large particles of substrate) and planophytes (unattached) are generally less prone to anoxia or hypoxia, exceptions being ice-encased polar haptophytes and estuarine and muddy shore macroscopic planophytes (pleustophytes) which can become hypoxic or anoxic as a result of burial in sediment or under new growth. A major difference between anoxia in low-salinity habitats and anoxia in saline habitats is the presence of high sulphate concentrations in most saline habitats including seawater. Use of sulphate as electron acceptor in microbial oxidation or organic carbon produces sulphide, with relatively less production of methane than in anoxic habitats with lower sulphate concentrations. In addition to its role as a toxin, 34 S/ 32 S natural abundance data show that 34 Sdepleted sulphide is directly or indirectly used as a sulphur source for roots and rhizomes of seagrasses and for the whole organism of emergent salt marsh herbs and mangroves. Granted the presence of hydrogen sulphide in the rhizosphere, its entry by lipid-solution permeation of the plasmalemma is inevitable. The balance of evidence favours the entry of hydrogen sulphide rather than the oxidation of 34 S-depleted sulphide to 34 S-depleted sulphate in an aerobic rhizosphere with subsequent entry of sulphate. © 1997 Annals of Botany Company

Influence of anoxia on free amino acid levels in blood, liver and skeletal muscles of the goldfish, Carassius aurantus L.

1. 1. Fiften free amino acids were quantified in blood, liver, white muscle and red muscle of fasting goldfish subjected to 12 hr of anoxia. Normoxic goldfish were used as controls. 2. 2. The anoxia treatment significantly raised the total pool of free amino acids in whole blood and liver. 3. 3. A general trend is observed in all the anoxic tissues: the free amino acids, for the most part, increase in absolute amounts. A strong accumulation is observed for some specific (groups of) free amino acids: alanine, the branched-chain amino acids and the aromatic free amino acids. 4. 4. Only the amide glutamine decreases substantially in the white muscle. 5. 5. These measurements indicate proteolysis of tissue proteins in anoxic goldfish and are interpreted as evidence for a coupling of glycolysis and amino acid catabolism.

Influence of anoxia, reoxygenation, and uncoupling on survival, respiration, and Trypsin-Inhibiting capacity of isolated pancreatic acinar cells

In the pathogenesis of acute pancreatitis, the events and mechanisms increasing the digestibility of the pancreatic acinar cells are widely unknown. Therefore, the possible contribution of a disturbed energy supply (provoked by anoxia or partial uncoupling) to the induction of autodigestion was studied in experiments on acinar cells isolated from the pancreas. During incubation viability, respiration under normal and maximally stimulated conditions, and trypsin-inhibiting capacity (TIC) of these cells were determined. With increasing duration of anoxia, the portion of surviving cells was strongly diminished, and the number of cells with blebs and vesicularly transformed endoplasmic reticulum was increased. Although the endogenous respiration was not influenced up to 1.5 h of anoxia, 30 min of anoxia substantially decreased the capacity of oxidative energy production. The survival curves were characterized by a self-accelerating course of cell destruction. The alteration of the cellular energy metabolism found its reflection in the decreased TIC of the cells.

Influence of anoxia on the functional activity of myocardial aminoacyl-tRNA synthetases

Influence of anoxia on the functional activity of myocardial aminoacyl-tRNA synthetases

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ＥＰに対するＡｎｏｘｉａの影響 モルモット胎仔の新生仔の比較:モルモット胎仔と新生仔の比較

Snail Distributions in Lake Erie: The Influence of Anoxia in the Southern Central Basin Nearshore Zone

Snail Distributions in Lake Erie: The Influence of Anoxia in the Southern Central Basin Nearshore Zone

Carbon Transport and Root Respiration of Split Root Systems of Phaseolus vulgaris Subjected to Short Term Localized Anoxia

The influence of anoxia on carbon transport and root respiration was evaluated by applying [U-(14)C]sucrose to the foliage. Translocation patterns to the root systems of two dry edible bean genotypes (Phaseolus vulgaris L.) were examined after a 3-day exposure to aerated and nonaerated environments. Localized anoxia of root systems was simulated by growing roots in split configurations and exposing half of the system to anoxic conditions. Anoxia of the root system for 72 hours reduced the movement of (14)C label into the roots with concurrent accumulations in the hypocotyl region. The translocation of (14)C label to anoxic roots was less than 50% of the aerated controls of both genotypes. Most of the (14)C label translocated to anoxic root systems was excluded from respiratory metabolism during the 3-hour pulse/chase period and was an order of magnitude less than the aerated controls. These observations suggest that the bulk of (14)C label which entered the root during the anoxic period was unavailable for metabolism by the enzymes of glycolysis and/or was diluted by a relatively large metabolite pool. A higher percentage of (14)C label was translocated to the aerated half of the localized anoxia treatment relative to the half of the aerated controls. The proportion of (14)C label translocated to the root system in the aerated control was 20 and 16% compared to 28 and 25% in the aerated localized anoxia treatment for the genotypes Seafarer and line 31908, respectively. Line 31908 partitioned a greater percentage of (14)C-labeled compounds to the actively growing fraction of the root system in the localized anoxia treatment than did Seafarer. This suggests a greater reliance on previously stored carbohydrate for immediate root growth in Seafarer than in line 31908.

Adenylate energy charge in three marine bivalve species during anoxia

Abstract Influence of anoxia on adenylate energy charge (AEC) has been studied with three bivalve species from the Western Baltic Sea, Macoma calcarea, Cyprina islandica and Astarte borealis, which represent different levels of tolerance to anoxia, increasing in the order listed. Under normoxic conditions (10°C, 16.5%°S) the adenylate energy charge (a measure for the potentially available energy of an organism, ranging from 0 to a hypothetical maximum of 1.0) accounted to 0.80 for M. calcarea, 0.79 for C. islandica and 0.55 for A. borealis. A subsequent exposure to anoxia resulted in a decrease of AEC in all three species, with the lowest AEC measured in A. borealis, the species with the best tolerance to anoxia. To investigate the influence of temperature, experiments with M. calcarea and A. borealis were also conducted at 5 and 15 °C. It was found that an increase of temperature leads to increased AEC values in M. calcarea, but to decreased levels in A. borealis. The adaptive value of being able to lowe...

Influence of anoxia and dinitrophenol on Ca2+ efflux and phosphorylase a activity in rabbit colon smooth muscle.

It was observed in earlier studies that when the phosphorylase alpha activity of rabbit colon smooth muscle was increased by anoxia or 2,4-dinitrophenol (DNP), the calcium content of the mitochondrial fraction decreased. Despite this, under basal conditions there was no significant increase in the Ca2+ content in the fraction consisting of microsomes and cytoplasm. In the present study it was therefore investigated whether mitochondrial Ca2+ released by anoxia and DNP is translocated from the smooth muscle cells into the extracellular fluid. The Ca2+ efflux from rabbit colon into a Ca2+-free Krebs-Ringer bicarbonate buffer was measured by using a Ca2+-selective electrode. Both anoxia and DNP (6.6 X 10(-5)M) increased the Ca2+ efflux from the smooth muscle cells. The local anaesthetic D-mepivacaine, at a concentration of 1 X 10(-3)M, reduced the increase in Ca2+ efflux and simultaneously enhanced the anoxic or DNP-induced rise in phosphorylase alpha activity. The replacement of external Na+ by choline was found to reduce the basal Ca2+ efflux and to moderately increase change in the Ca2+ efflux, but the increase in phosphorylase alpha activity was greater than in the physiological buffer containing 137 mM Na+. These observations support the suggestion that anoxia and DNP, by releasing Ca2+ from the mitochondria, increase the phosphorylase alpha activity of smooth muscle.

Influence of anoxia and dinitrophenol on the phosphorylase a activity and the cyclic nucleotide content of smooth muscle.

The effect of anoxia or 2,4-dinitrophenol (DNP) on the phosphorylase activity and the cyclic AMP and the cyclic GMP content was studied in smooth muscle preparations. When the aerobic conditions were changed to anaerobic in experiments on bovine mesenteric artery, there was a significant increase in the activity of phosphorylase a during the first 60 min. We had observed a reduction of the glycogen content of the artery during this time period, which accounted for about 2/3 of the increase in lactate production (Pasteur effect). Under anaerobic conditions the content of cyclic AMP in the vessel was not changed, and the increase in phosphorylase a activity was not inhibited by a blockade of adrenergic beta-receptors. DNP, which like anoxia inhibits the mitochondrial production of ATP, increased the phosphorylase a activity to the same extent as anoxia. Anoxia and DNP also enhanced the activity of phosphorylase a in pig thoracic aorta and rabbit colon smooth muscle. In thoracic aorta both anoxia and DNP produced a more transient and smaller increase in the phosphorylase a activity than in the mesenteric artery. The Pasteur effect was also relatively smaller (100%) in thoracic aorta than in mesenteric artery (400%). It is suggested that an anoxic increase in the phosphorylase a activity participates in the Pasteur effect in smooth muscle.

The influence of anoxia and ethanol on barley seed death

SUMMARYSurvival of deteriorated barley seeds in wet soil was improved by exposure to 70% oxygen compared with that in air and decreased by the imposition of anoxia. Deteriorated seeds were more sensitive to anoxia than non‐deteriorated seeds, the former died within 4 days, while the latter survived more than 7 days.Ethanol accumulated in non‐deteriorated seeds in wet soil conditions during the first 24 h and thereafter declined, while it increased to higher concentrations over 3–4 days in deteriorated seeds. High concentrations of ethanol were recorded in seeds in anaerobic conditions regardless of the level of deterioration.It was concluded that oxygen diffusion to the seeds was severely restricted in wet soil resulting in a switch to anaerobic respiration, the products of which, indicated by ethanol content, accumulated within the tissues. Non‐deteriorated seeds tolerated higher concentrations of ethanol than deteriorated seeds and the coleorhiza extruded through the covering layers more rapidly facilitating gaseous exchange, while in the latter, anaerobic products accumulated to toxic levels.

Anaerobic metabolism of goldfish,Carassius auratus (L.). Influence of anoxia on mass-action ratios of transaminase reactions and levels of ammonia and succinate

Changes in the concentrations of ammonia, glutamate, alanine, aspartate, α-ketoglutarate, oxaloacetate and succinate were measured in freeze-clamped lateralred muscle, dorsal white muscle and liver, and in rapidly cooled blood of goldfish after 12 h of anoxia. Alanine accumulation, succinate accumulation and aspartate depletion are observed in all tissues examined; in the liver the concentrations of glutamate increase and those of ammonia decrease. The mass-action ratio of the glutamate-pyruvate transaminase-catalyzed reaction stays within one order of magnitude from thermodynamic equilibrium in the direction of alanine formation. The mass-action ratio of the glutamate-oxaloacetate transaminase reaction is far from equilibrium when measured oxaloacetate concentrations are used. When levels of free oxaloacetate are calculated from LDH and MDH equilibrium constants, the mass-action ratio of glutamate-oxaloacetate transamination is close to equilibrium in the direction of aspartate formation. Since neither alanine nor glutamate decreases, and since ammonia gradients suggest a continuous ammonia production in all tissues examined, anaerobic proteolysis is assumed. A possible coupling between amino acid catabolism and ethanol production is discussed.

The influence of anoxia or oxygenation on the induction of chromosome aberrations in human lymphocytes by 15-MeV neutrons

Dicentric and total aberration yields induced in human lymphocytes by 15-MeV neutrons under conditions of oxygenation and of anoxia have been fitted to a dose-response curve using the function Y = αD + βD 2. An oxygen-enhancement ratio (OER) ranging from 3.7 at low yields to 1.6 at high yields was calculated from the co-efficients of the dicentric yield curves and evidence is presented which suggests that oxygen does not act as a dose-modifying agent in this system. High dose RBE values of 1.2 and 2.1 with respect to 250 kVp X-rays for oxygenated and anoxic conditions were also obtained. Coefficients for total aberration yield gave similar values to dicentrics for both OER and RBE