Adenylate Energy Charge Values Research Articles

Altered energy status of primary cerebellar granule neuronal cultures from rats exposed to lead in the pre- and neonatal period

This paper examines the effect of pre- and neonatal exposure of rats to lead (0.1% lead acetate in drinking water, resulting in rat offspring whole blood lead concentration (Pb-B) 4 μg/dL) on the energy status of neuronal mitochondria by measuring changes in ATP, ADP, AMP, adenosine, TAN concentration, adenylate energy charge value (AEC) and mitochondrial membrane potential in primary cerebellar granule neurons (CGC) in dissociated cultures. Fluorescence studies were performed to imaging and evaluate mitochondria mass, mitochondrial membrane potential, intracellular and mitochondrial reactive oxygen species (ROS) production. The Na +/K + ATPase activity in intact CGC was measured spectrophotometrically. Our data shows that pre- and neonatal exposure of rats to Pb, even below the threshold of whole blood Pb value considered safe for people, affects the energy status of cultured primary cerebellar granule neurons through a decrease in ATP and TAN concentrations and AEC value, inhibition of Na +/K + ATPase, and increase in intracellular and mitochondrial ROS concentration. These observations suggest that even these low levels of Pb are likely to induce important alterations in neuronal function that could play a role in neurodegeneration.

Biochemical changes in oyster tissues and hemolymph during long-term air exposure

The Pacific oyster Crassostrea gigas is a sessile bivalve that inhabits the intertidal zone and therefore frequently exposed to air during the tidal cycle. It is highly adaptive to hypoxic conditions. We have studied the physiological state of oysters during long-term exposure to air. The oysters became hypoxic when exposed to air or hypoxic seawater. The 50% lethal time of oysters exposed to air at 4, 15 and 20°C was 47.8, 15.9 and 12.2 days, respectively. The hemolymph pH decreased by day 3; however, it showed a slight increase by day 5 at both 4 and 20°C. The adenylate energy charge (AEC) values decreased rapidly on the first day of air exposure in the adductor muscle, mantle, gill and body trunk, and these decreases were accompanied by decreases in ATP concentrations and increases in AMP concentrations. The AEC values in all of the tissues had fallen to below 30% by day 50 of air exposure at 4°C. These data suggest that the energy state of oysters deteriorates rapidly with air exposure. Consequently, AEC values may be useful indices of the physiological state of the oyster during long-term exposure to air.

Purine Turnover Metabolites and Selected Antioxidants in Blood of Goats during the Periparturient Period

The aim of this study was to examine the relationships between the erythrocyte concentrations of ATP, ADP, AMP, NAD+, NADP+ and adenylate energy charge (AEC) and their metabolites: inosine (Ino), hypoxanthine (Hyp), uric acid (UA), selected blood antioxidants: superoxide dismutase (SOD), glutathione reductase (GR) of goats during the periparturient period. The study was conducted on 12 clinically healthy pregnant goats (Capra hircus) - 75% genotype of the Polish noble white aged between 2-3 years. Blood was taken from the external jugular vein early in the morning before feeding and obtained twice (4 weeks and 1 week) before delivery and twice (2 and 3 weeks) after delivery. The ATP concentration did not change significantly. One week before delivery ADP, AMP and Ino concentrations were significantly higher and AEC value significantly lower compared to values in the third week after delivery (p ≤ 0.02, p ≤ 0.05, p ≤ 0.03 and p ≤ 0.01, respectively). One week before and two weeks after delivery we observed a significant increase in SOD and GR activities and an increase in NAD+ and NADP+ concentrations but a significant decrease in Hyp and UA concentrations. Constant ATP concentration and the changes in the dynamics and tendency of Hyp and UA concentrations show that in the periparturient period in goats, purine metabolism undergoes adaptive changes. The balance between resynthetic processes and adenine nucleotide degradation is retained in order to level the oxygen and energy lacks. The results of our study show that the maintenance of prooxidative homeostasis in goats of peripartal period depends mainly on enzymatic mechanisms.

Metabolic biomarkers related to energy metabolism in Saudi autistic children

Objectives Energy metabolism is usually manipulated in many neurodegenerative diseases. Autism is considered a definable systemic disorder resulting in a number of diverse factors that may affect the brain development and functions both pre and post natal. The increased prevalence of autism will have enormous future public implications and has stimulated intense research into potential etiologic factors. This study aims to establish a connection between autism and the deterioration accompanied it, especially in the brain cognitive areas through a postulation of energy manipulation. Materials and methods The biochemical changes in activities of enzymes and pathways that participate in the production of ATP as the most important high-energy compound needed by the human brain were measured in Saudi autistic children. Na +/K +ATPase, ectonucleotidases (NTPDases) (ADPase and ATPase) and creatine kinase (CK), were assessed in plasma of 30 Saudi autistic patients and compared to 30 age-matching control samples. In addition, adenosine mono, di and trinucleotides (ATP, ADP, and AMP) were measured calorimetrically in the red blood cells of both groups and the adenylate energy charge (AEC) was calculated. Moreover, lactate concentration in plasma of both groups was monitored. Results The obtained data recorded 148.77% and 72.35% higher activities of Na +/K +ATPase and CK respectively in autistic patients which prove the impairment of energy metabolism in these children compared to age and sex matching healthy controls. While ADPase was significantly higher in autistic patients, ATPase were non-significantly elevated compared to control. In spite of the significant increase of Na +/K +ATPase activity in autistic patients, there was no significant difference in the levels of ATP, ADP, and AMP in both groups and the calculated AEC values were 0.814 ± 0.094 and 0.806 ± 0.081 for autistic and control groups respectively. The unchanged AEC value in autistic patients was easily correlated with the induced activity of CK and ADPase as two enzymes playing a critical role in the stabilization of AEC. Lactate as an important energy metabolite for the brain was significantly higher in autistic patients compared to control showing about 40% increase. Conclusion The present study confirmed the impairment of energy metabolism in Saudi autistic patients which could be correlated to the oxidative stress previously recorded in the same investigated samples. The identification of biochemical markers related to autism would be advantageous for earlier clinical diagnosis and intervention.

Disturbances of energetic metabolism in rat epididymal epithelial cells as a consequence of chronic lead intoxication

Adult male Wistar rats were intoxicated with 1% lead acetate (PbAc) administered in drinking water for nine months, which amounts to a period five times longer than the duration of one spermatogenesis. There were mitochondrial ultrastructure disorders of epididymal epithelial cells observed in PbAc-treated rats; also a significant lead-induced decrease in ATP concentration in epididymal epithelial cells (by 32%, P < 0.05), Adenylate Energy Charge value (AEC) (by 8%, P < 0.05) and an increase in ADP (28.5%, P < 0.05), AMP (27%, P < 0.05) and adenosine (by 56%, P < 0.05). The results were measured using high performance liquid chromatography (HPLC) and detected even at low lead concentrations in whole blood (M:7.03 μg/dL; Q1-Q3: 2.99-7.65). The function of mitochondria in cultured epididymal epithelial cells of control and PbAc-treated animals were evaluated using fluorophores: Mitotracker Green FM and JC-1. After incubation with Mitotracker Green FM, we observed active mitochondria producing bright green fluorescence in the cytoplasm of cultured epididymal epithelial cells, both in the control group and the Pb-treated animals. Incubation of cultured epididymal epithelial cells of animals from both groups produced red-orange fluorescence with the mitochondrial JC-1 probe indicating mitochondria with high membrane potential (ΔΨm > 80-100 mV) and green fluorescence in the mitochondria with low membrane potential (ΔΨm < 80 mV). The results showed that a chronic low-level exposure to lead, even without severe clinical symptoms of contamination, disrupted the ultrastructure and energy metabolism of mitochondria in epididymal epithelial cells.

Changes in the adenylate energy charge of Nippostrongylus brasiliensis and Nematodirus battus during the development of immunity to these nematodes in their host.

Infection of rats with 2000 infective juveniles of Nippostrongylus brasiliensis and of lambs with 60 000 infective juveniles of Nematodirus battus results in a well-marked immunity to these nematodes in their respective host. There is a fall in the adenylate energy charge value of these nematodes during the course of these infections, reaching values of 0.37 in males and 0.27 in females of N. brasiliensis, and 0.31 in males and 0.23 in females of N. battus towards the end of the infections. In hosts given relatively small numbers of infective juveniles, the values for the nematodes removed from the hosts late in the infection remain at a relatively high level. These results indicate that the immune response of the host may affect the energy status of these nematodes, and this could help to explain their subsequent expulsion from the immune host.

Inhibition of erythrocyte phosphoribosyltransferases (APRT and HPRT) by Pb 2+: A potential mechanism of lead toxicity

Many reports show that red blood cells of people exposed to lead have a decreased ATP concentration, decreased adenylate energy charge value and many metabolic and morphological abnormalities. Since the synthesis of nucleotides in erythrocytes occurs only through salvage pathways, we hypothesized that a decrease in nucleotide concentrations may be caused by lead-induced inhibition of erythrocyte phosphoribosyltransferases: adenine APRT (EC 2.4.2.7) and hypoxanthine-guanine HPRT (EC 2.4.2.8). These enzymes enable the reutilization of purine bases (adenine, guanine, hypoxanthine) converting them to mononucleotides (AMP, GMP, IMP), substrates for the synthesis of high-energy nucleotides. To confirm the hypothesis two experiments were performed: (i) in vitro, using a lysate of human erythrocytes incubated (5, 10, 30 min) with lead ions (100 μM, 10 μM, 1 μM, 500 nM, 100 nM lead acetate) and 100 μM sodium acetate for the control, (ii) in vivo, using a lysate of rat erythrocytes taken from rats chronically exposed to lead (0.1% lead acetate in drinking water for 9 months, resulting in whole blood lead concentration 7 μg/dL). The activities of APRT and HPRT were determined using HPLC method, which allowed concurrent determination of the activity of both enzymes in erythrocyte lysates. We have shown that, lead ions: (i) moderately inhibit both phosphoribosyltransferases in erythrocytes, this influence being detectable even at very low concentrations (ii) participate in hemolysis, the intensity of which negatively correlates with the activity of phosphoribosyltransferases. Our results indicate the necessity of further research on the role of lead-induced APRT and HPRT inhibition as one of the mechanisms of lead toxicity.

A kinetic study of a ternary cycle between adenine nucleotides

In the present paper, a kinetic study is made of the behavior of a moiety-conserved ternary cycle between the adenine nucleotides. The system contains the enzymes S-acetyl coenzyme A synthetase, adenylate kinase and pyruvate kinase, and converts ATP into AMP, then into ADP and finally back to ATP. L-Lactate dehydrogenase is added to the system to enable continuous monitoring of the progress of the reaction. The cycle cannot work when the only recycling substrate in the reaction medium is AMP. A mathematical model is proposed whose kinetic behavior has been analyzed both numerically by integration of the nonlinear differential equations describing the kinetics of the reactions involved, and analytically under steady-state conditions, with good agreement with the experimental results being obtained. The data obtained showed that there is a threshold value of the S-acetyl coenzyme A synthetase/adenylate kinase ratio, above which the cycle stops because all the recycling substrate has been accumulated as AMP, never reaching the steady state. In addition, the concept of adenylate energy charge has been applied to the system, obtaining the enabled values of the rate constants for a fixed adenylate energy charge value and vice versa.

Intracellular ATP and total adenylate concentrations are critical predictors of reovirus productivity from Vero cells

The productivity of reovirus type-3 Dearing was studied in cultures of Vero cells in serum-free media. Viral productivity was dependent upon the metabolic state of the cells rather than the phase of growth at which the cells were infected. Cells at different energy states were established by 24-h incubation in nutrient-depleted media. This resulted in variable intracellular nucleotide concentrations but high cellular viability was maintained. Of the nucleotides analyzed at the time of infection only the intracellular [ATP] and total adenylate nucleotides were positively correlated with viral productivity. The correlated data followed a sigmoidal plot with an equation defined by polynomial regression analysis. Apparent threshold values of 3.2 fmol/cell and 3.3 fmol/cell were established for ATP and total adenylate, respectively, at which the viral production was 50% the maximal value. Cultures with lower ATP and total adenylate levels at the time of infection resulted in as much as a 95% reduction in overall viral titer compared to the control. The adenylate energy charge (AEC) showed a negative correlation with viral production with an AEC value >0.97 resulting in low virus productivity. Intracellular ATP or total adenylate concentration at the point of infection may be used as a predictor of viral yield in bioprocesses designed for virus/vaccine production.

Adenylate Nucleotides and 2,3-Biphosphoglycerate Concentration in Erythrocytes of Growing Wielkopolska Stallions

The aim of this study was to examine the relationships between the concentrations of adenylate nucleotides (ATP, ADP, AMP), total nucleotide pool (TAN), adenylate energy charge (AEC) and 2,3-biphosphoglycerate (2,3-BPG) in the erythrocytes of young horses in the period of their rapid growth and development. The studies were conducted on 10 young Wielkopolska breed stallions for two years; Group A: 1-month-old, Group B: 3-month-old, Group C: 6-month-old, Group D: 1-year-old, and Group E: 2-year-old. ATP, ADP and AMP concentrations in the erythrocytes were determined by HPLC. 2,3-BPG was determined using the Calbiochem USA kit. We observed that erythrocyte ATP, ADP, AMP and TAN concentrations significantly decreased with age (p &lt; 0.001), while 2,3-BPG concentration and AEC values significantly increased with age. A significant correlation between the ATP and TAN concentrations was found within all the examined groups (p &lt; 0.05). A significant correlation was also found between ATP concentration and AEC values (except 12 month-old stallions). Moreover, an age-dependent negative correlation between ATP and 2,3-BPG (r = -0.81) was found. The conclusion is that the adenylate energy charge and erythrocyte 2,3-BPG variables in the Wielkopolska stallions mainly depend on age, thus warranting the use of specific age-related reference values for this breed's foals.

The effect of new non-cross resistant antitumour agents on the energy state of human erythrocytes.

Multidrug resistance (MDR) of tumour cells is related to the overexpression of ATP-dependent pumps responsible for the active efflux of antitumour agents out of resistant cells. Benzoperimidine and anthrapyridone compounds exhibit comparable cytotoxic activity against sensitive and MDR tumour cells. They diffuse extremely rapidly across the plasma membrane and render the ATP-dependent efflux inefficient. Such uptake could disturb an energy metabolism of normal cells possessing an elevated level of ATP-dependent proteins, especially erythrocytes having a high level of the MRP1, MRP4 and MRP5 proteins. In this study the effect of five antitumour agents: benzoperimidine (BP1), anthrapyridones (CO1, CO7) and reference drugs used in the clinic: doxorubicin (DOX) and pirarubicin (PIRA), on the energetic state in human erythrocytes has been examined. These compounds have various types of structure and kinetics of cellular uptake (slow--DOX, CO7, moderate--PIRA, fast--BP1, CO1) resulting in their different ability to saturate ATP-dependent transporters. The energetic state of erythrocytes was examined by determination of purine nucleotide contents (ATP, ADP, AMP), NAD(+) and values of adenylate energy charge (AEC) using an HPLC method. It was found that the level of nucleotides as well as the AEC value of erythrocytes were not changed during 24 h of incubation with these agents independently of their structure and ability to saturate ATP-dependent pumps. This is a very promising result in view of their potential use in the clinic as antitumour drugs against multidrug resistant cancers.

Determination of the adenylate energy charge (AEC) as a tool to determine the physiological status of macroalgal tissues after UV exposure

M. Hünken, U. Karsten and C. Wiencke. 2005. Determination of the adenylate energy charge (AEC) as a tool to determine the physiological status of macroalgal tissues after UV exposure. Phycologia 44: 249–253.A method was developed to extract adenine nucleotides AMP, ADP, and ATP from marine macroalgal tissue to gain information on the cellular energy charge. Quantification was carried out by high performance liquid chromatography (HPLC). Three species from the rocky shore of the island of Helgoland (German Bight) were examined: Laminaria saccharina (Phaeophyta), Chondrus crispus (Rhodophyta), and Ulva lactuca (Chlorophyta). In L. saccharina and C. crispus, the adenylate energy charge (AEC) was determined in different thallus regions. AEC varied in relation to tissue age and function. Higher AEC values typically occurred in thallus regions with meristematic activity. Furthermore, L. saccharina and U. lactuca were exposed to UV-A and elevated UV-B radiation. The AEC was calculated and the maximal quantum yield of photosystem II (Fv/Fm) was determined as indicators for UV stress. In both species, the AEC remained at high values (0.72 ± 0.04), while Fv/Fm dropped rapidly. The results show that the photosynthesis of the phaeophyte is more resistant to UV radiation than the chlorophyte.

Adenylates in the soil microbial biomass at different temperatures

Five soils from temperate sites (Germany; 2 arable and 3 grassland) were incubated aerobically at 5, 10, 15, 20, 25, 35, and 40 °C for 8 days. Soils were analysed for soil microbial biomass C, biomass N, AMP, ADP, and ATP to determine whether the increase in the ATP-to-microbial biomass C ratio with increasing temperature was either due to an increase in the adenylate energy charge (AEC) or de novo synthesis of ATP, or both. Around 80% of the variance in microbial biomass C and biomass N was explained by differences in soil properties, only 7% by the temperature treatments. Averaging the data of all 5 soils for each incubation temperature, the microbial biomass C content decreased with increasing temperature from 15 to 40 °C continuously by 2.5 μg g −1 soil °C −1 after 8-days' incubation. However, this decrease was not accompanied by a similar decrease in microbial biomass N. The average microbial biomass C/N ratio was 6.8. Between 54 and 76% of the variance in AMP, ADP, ATP and the sum of adenylates was explained by differences in soil properties and between 14 (ADP) and 27% (ATP) by the temperature treatments. However, temperature effects on AMP and ADP were variable and inconsistent. In contrast, ATP and consequently also the sum of adenylates increased continuously from 5 to 30 °C followed by a decline to 40 °C. The AEC showed similarly a small, but significant increase with increasing temperature from 0.73 to 0.85 at 30 °C. Consequently, the majority of the variance, i.e. roughly 60% in AEC values, but also in ATP-to-microbial biomass C ratios was explained by the incubation temperature. The mean ATP-to-microbial biomass C ratio increased from 4.7 μmol g −1 at 5 °C to a 2.5 fold maximum of 12.0 μmol g −1 at 35 °C. This increase was linear with a rate of 0.26 μmol ATP g −1 microbial biomass C °C −1. The energy for the extra ATP produced during temperature increase is probably derived from an accelerated turnover of endocellular C reserves in the microbial biomass.

The effect of lead ions on the energy metabolism of human erythrocytes in vitro

The aim of this work was to evaluate the influence of chronic exposure to lead ions on the parameters of energetic status of human erythrocytes in vitro. Umbilical cord erythrocytes were incubated with lead acetate at final lead ion concentrations ranging from 10 to 200 μg/dl. ATP, ADP, AMP, adenosine, GTP, GDP, GMP, guanosine, IMP, inosine, hypoxanthine, NAD and NADP concentrations in erythrocytes were determined using HPLC. Scanning electron micrographs of erythrocytes were taken. The mean concentrations of ATP, GTP, NAD and NADP, and mean values of adenylate energy charge (AEC) and GEC in cells incubated at the presence of lead ions were significantly lower after 20 h of incubation. Concentrations of purine degradation products (Ado, Guo, Ino) and Hyp were significantly higher. It is suggested that lead ions affect the energy metabolism of erythrocytes. Morphological changes in erythrocytes correspond to the increase of lead ions in the incubation mixture and to the decrease of ATP concentration in erythrocytes. A decrease in NAD and ATP concentration in erythrocytes could be a sensitive indicator of energy process disturbance, useful in monitoring in case of chronic lead exposure.

Relation between respiration, ATP content, and Adenylate Energy Charge (AEC) after incubation at different temperatures and after drying and rewetting

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Impact of root morphology on metabolism and oxygen distribution in roots and rhizosphere from two Central Amazon floodplain tree species.

Adaptation to prolonged flooding was investigated using cuttings of two tree species from the Central Amazon white-water floodplain (Várzea). Morphological features and oxygen distribution patterns were correlated with metabolic changes under hypoxia, such as alterations in alcohol dehydrogenase (ADH) activity and adenylate energy charge (AEC) of root cells. Salix martiana (Leyb.) was able to react to hypoxic growth conditions with formation of adventitious roots rich in lysigenous aerenchyma, which facilitates root aeration by longitudinal oxygen transport and rhizosphere oxidation by radial oxygen loss (ROL). The oxygen concentration on the surface of adventitious roots of S. martiana reached 2-3 mg O2 L-1. The low resistance to gas exchange in Salix roots was reflected by low ADH activities, which ranged between 0.03-0.1 μmol NADH mg -1 min-1, and AEC values of 0.8-1 under hypoxic conditions. Adventitious roots were also formed by Tabernaemontana juruana ([Markgr.] Schumann ex. J.F. Macbride) during growth under low-oxygen conditions, although at a later stage. The gas-space continuum in roots of T. juruana was less pronounced, resulting in a 10-fold lower oxygen concentration in the root cortex under oxygen stress compared with adventitious roots of Salix. The lower oxygen content was reflected in 6-fold higher ADH activities and decreased AEC values. ROL occurred only at the non-suberized root tip, suggesting that the suberized hypodermis functions as a barrier against gas exchange between the root and the rhizosphere. These findings indicate that different strategies of adaptation to low oxygen levels are realized in the two species under investigation that occur naturally in the same ecosystem but inhabit different elevation sites.

THE PROTECTIVE POTENCY OF VITAMINS E AND C IN METHANOL-INDUCED OXIDATIVE STRESS AND RETINOTOXICITY

The protective effects of vitamins E and C against methanol-induced free radical production with its subsequent tissue injury in liver and retina of male albino rats were assessed. The rats were divided into four groups: (1) control, (2) antioxidant (Ao) control group receiving 5 mg of each vitamin, E and C, (3) daily ip-injected methanol (2 mL/kg b.wt.) group, killed after three and six doses, and (4) Ao/methanol group administered the vitamins 3 weeks prior to and along with methanol injection and killed as the latter group [Sharpe et al. Methanol Optic Neuropathy: A Histopathological Study. Neurology 1982, 32 (10), 1093–1100].Methyl alcohol drastically altered the Ao defense system and energy status of rat liver, where highly significant depletion of glutathione levels and inhibition of superoxide dismutase activity, concurrent with significant increase in thiobarbituric acid reactive substances indicating marked elevation in lipid peroxidation. These effects were reversed when the vitamins were administered denoting their role in promoting the Ao defense system. Furthermore, they also increased the methanol-induced depletion in adenylate energy charge, phosphate potential, and ATP values. The amelioration in the energy status as a result of vitamins E and C supplementation suggests that their role as Aos is effective in relieving the impaired oxidative phosphorylation in order to increase the energy demand under physiologically stressful conditions.Histopathological and ultrastructural results of rat retina confirmed the protective effect of Ao vitamins. As compared to the methanol-intoxicated group, the protected group showed preservation of the membranous structures of the retinal cells, especially mitochondria that assumed their normal shape. This may be attributed to the inhibition of free radical production and lipid peroxidation and subsequently minimum degree of tissue damage. Amelioration of mitochondrial structure reflected the improvement of impaired oxidative phosphorylation of intoxicated animals with an approximately normal level of energy demand. This suggests that Ao vitamins may alter the retinotoxic effects of methanol by promoting the internal Ao defense system and preserving the energy status of the animal.

Heavy metal contamination and physiological variability in the Brazilian mangrove crabs Ucides cordatus and Callinectes danae (Crustacea: Decapoda)

Physiological studies were made on the crabs Ucides cordatus (L.) and Callinectes danae sampled from populations living in “polluted” mangroves on the southeast littoral of Brazil. Analysis of Cu, Cd, Zn, and Fe of sediments and crab tissues showed interspecific differences in tissue concentrations, and significantly higher levels of Cu, Cd, and Zn in “polluted” populations compared to “unpolluted” crabs living in uncontaminated mangrove in the same geographical area. Individuals of both species from the polluted site showed significantly greater capacities for regulating blood osmotic concentrations at low salinity (9‰). However, U. cordatus showed a reduced hypo-regulatory ability in 34‰S. Differences in ionoregulation were also seen. “Polluted”C. danae showed significantly higher Na/ K-ATPase levels in posterior gills compared to “unpolluted” crabs. Oxygen consumption rates (M˙O2) were elevated in U. cordatus, but depressed in C. danae from the “polluted” population. Individuals of both species from this site showed significantly lower O:N ratios, mainly because of an increased net efflux of ammonia. Adenylate energy charge (AEC) values of muscle and hepatopancreas in “unpolluted” and “polluted” populations of both species were not significantly different. These physiological differences are discussed in relation to the known acute physiological and metabolic effects of heavy metals in crustaceans, and interpretated in the light of possible adaptive changes following long-term exposure to contamination.

Adenylates and adenylate-energy charge in submerged and planktonic cultures of Salmonella enteritidis and Salmonella typhimurium

Adenine nucleotide values and adenylate energy charge (AEC) were measured during the growth of Salmonella enteritidis and Salmonella typhimurium as submerged colonies in agarose gel and gelatin gel, and as planktonic cells in broth. Growth in all three systems showed similar trends with a ten-fold decrease in total adenylate pool during exponential growth, before attaining a fairly stable value throughout stationary phase. AEC values were generally low, (≈0.66), but did rise slightly during stationary phase. The large proportion of dead cells during early exponential phase may have contributed to the adenosine diphosphate and adenosine monophosphate pools, through cell lysis or excretion, and it is suggested that this was likely to account for the low values of AEC. In agarose and gelatin gelled cultures the percentage of adenosine triphosphate (ATP) in relation to the total adenylates showed random fluctuations. This was contrary to the broth culture where percentage ATP was highest after 12 h and the data formed a smooth curve. These data demonstrated that considerable physiological heterogeneity exists within a colony of bacteria growing in a gel matrix and by analogy a food material also, and that AEC is a poor indicator of cell viability in such systems.

The effect of soaking injury in seeds ofPhaseolus vulgarisL. on germination, respiration and adenylate energy charge

AbstractSubmergingPhaseolus vulgariscv. Top Crop seed in air-saturated water for 16 h markedly depresses subsequent germination. This is termed soaking injury. The postulate by Norton (1986) that soak-injured seeds merely run out of available energy was investigated. Soaking in air-saturated water reduced the total respiration (VT; in terms of O2uptake) of excised axes and cotyledons resulting in lower ATP levels. The contribution of both the mitochondrial cytochrome respiratory pathway (VCYT) and the alternative respiratory pathway (VALT) to the total respiration (VT) was significantly lower in these axes. However, the adenylate energy charge (AEC) values for both axes and cotyledons excised from soak-injured seeds did not drop below 0.6, the threshold value indicating death of plant material. Differences between the ultrastructure of mitochondria in the radicle tips of axes from unsoaked and water-soaked seeds were observed. However, the capacity to operate the Krebs cycle was similar in all axes and soak-injured seeds were still capable of germinating when the testas were removed or the seeds dried. This means that axes contained a sufficient amount of carbohydrates and potential energy to germinate after soaking. Moreover, soak-injured seeds produced ethanol at a rate which was five times higher than that of unsoaked control seeds, both during the soaking and post-soaking periods. Together with the low rate of oxygen consumption by soak-injured seeds during the same soaking and incubation time, it appears that soak-injured seeds lack the potential to switch from an anaerobic to an aerobic respiration pattern causing low ATP levels in these axes. It is speculated that the latter seems to be the result of limited pyruvate supply, probably due to accelerated and prolonged fermentation or futile combustion through other pathways or both.