Adenylate Energy Charge Levels Research Articles

Energy metabolism of juvenile scallops Nodipecten subnodosus under acute increased temperature and low oxygen availability

High temperature increases energy demand in ectotherms, limiting their physiological capability to cope with hypoxic events. The present study aimed to assess the metabolic tolerance of juvenile Nodipecten subnodosus scallops to acute hyperthermia combined with moderate hypoxia. A previous study showed that juveniles exhibited a high upper temperature limit (32 °C), but the responses of juveniles to combined hyperthermia and low dissolved oxygen are unknown. Scallops were exposed to control conditions (treatment C: 22 °C, ∼7.1 mg O2 L−1 or PO2 156.9 mmHg), acute hyperthermia under normoxia (treatment T: 30 °C, ∼6.0 mg O2 L−1 or PO2 150.9 mmHg) or acute hyperthermia plus hypoxia (treatment TH: 30 °C, ∼2.5 mg O2 L−1 or PO2 62.5 mmHg) for 18 h. In T, juveniles exhibited an enhanced oxygen consumption, together with a decrease in adenylate energy charge (AEC) and arginine phosphate (ArgP), and with no changes in metabolic enzyme activity in the muscle. In TH, scallops maintained similar AEC and ArgP levels in muscle as those observed in T treatment. This response occurred along with the accumulation of inosine monophosphate and hypoxanthine. Besides, reduced citrate synthase and pyruvate kinase activities, enhanced hexokinase activity, and a higher octopine dehydrogenase/lactate dehydrogenase ratio in the mantle indicated the onset of anaerobiosis in TH. These responses indicate that juvenile scallops showed tissue-specific compensatory responses regarding their energy balance under moderate hypoxia at high temperatures. Our results give an insight into the tolerance limit of this species to combined hyperthermia and hypoxia in its northern limit of distribution.

Effects of stunning methods on pre rigor changes in rainbow trout (Oncorhynchus mykiss) reared at two different temperatures

The effects of two stunning methods (carbon monoxide asphyxia, CO, and electroshock, E) on blood plasma parameters, rigor index, fillet pH and shape changes, ATP breakdown and Adenylate Energy Charge (AEC) in muscle immediately post mortem were investigated in rainbow trout (Oncorhynchus mykiss) kept in tanks containing water set at 8 °C or 12 °C. Both the methods here adopted induced a stress-response which, however, was not able to affect the rigor mortis development and fillet pH. The fillets from the E group showed the strongest length contraction and width increase at 48 h post mortem. The CO stunning method exhibited the highest levels of both ATP and AEC in the muscle immediately after death, equal to 2.28 µmol/g and 0.83, respectively, while 1.12 µmol/g and 0.64 values were found in the E group. In addition, we found that the water temperature might interact with the stunning method and minimise the stress response. In the present trial, the most suitable use of the CO stunning method would be coupled with 12 °C of rearing water temperature to better preserve ATP and AEC in muscles. Highlights CO stunning preserves ATP and AEC in trout muscle better than electrical stunning Water temperature might interact with the stunning and minimise the stress response CO stunning is suggested to be coupled with 12 °C of water temperature Electricity should be avoided at 8 °C of water temperature

Responses to thermal and salinity stress in wild and farmed Pacific oysters Crassostrea gigas

The Pacific oyster Crassostrea gigas was introduced from Japan to many countries in the world for oyster farming, resulting in the establishment of wild populations in intertidal zones and resource competition with local faunas. This study examined physiological responses of wild oysters and farmed oysters to thermal (15°C, 25°C, 37°C and 44°C) and salinity stress (39, 50 and 60ppt). The wild oysters produced more 72kDa heat shock proteins when the temperature increased from 15°C to 25°C and 37°C and the salinity increased from 39 to 50 and 60ppt. However, the amount of 69kDa heat shock protein was similar between farmed and wild oysters when the temperature increased from 15°C to the sublethal temperature 37°C, but it was lower in wild oysters than in farmed oysters when the temperature increased from 15°C to the lethal temperature 44°C. In the tissues, wild oysters used more glycogen to promote metabolic activities by increasing the level of AEC (adenylate energy charge). The results suggest that farmed oysters might have limited ability to cope with heat stress due to low energy reserve and glycolysis activity for HSP synthesis. This study provides experimental evidence on differential responses between wild and farmed oysters to temperature and salinity changes, leading to a better understanding on the pattern of distribution for invading oyster species in the marine environment and the adaptation of marine invertebrates to the threat of climate change.

Asparagine attenuates intestinal injury, improves energy status and inhibits AMP-activated protein kinase signalling pathways in weaned piglets challenged with Escherichia coli lipopolysaccharide.

The intestine requires a high amount of energy to maintain its health and function; thus, energy deficits in intestinal mucosa may lead to intestinal damage. Asparagine (Asn) is a precursor for many other amino acids such as aspartate, glutamine and glutamate, which can be used to supply energy to enterocytes. In the present study, we hypothesise that dietary supplementation of Asn could alleviate bacterial lipopolysaccharide (LPS)-induced intestinal injury via improvement of intestinal energy status. A total of twenty-four weaned piglets were assigned to one of four treatments: (1) non-challenged control; (2) LPS+0 % Asn; (3) LPS+0·5 % Asn; (4) LPS+1·0 % Asn. On day 19, piglets were injected with LPS or saline. At 24 h post-injection, piglets were slaughtered and intestinal samples were collected. Asn supplementation improved intestinal morphology, indicated by higher villus height and villus height:crypt depth ratio, and lower crypt depth. Asn supplementation also increased the ratios of RNA:DNA and protein:DNA as well as disaccharidase activities in intestinal mucosa. In addition, Asn supplementation attenuated bacterial LPS-induced intestinal energy deficits, indicated by increased ATP and adenylate energy charge levels, and decreased AMP:ATP ratio. Moreover, Asn administration increased the activities of key enzymes involved in the tricarboxylic acid cycle, including citrate synthase, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase complex. Finally, Asn administration decreased the mRNA abundance of intestinal AMP-activated protein kinase-α1 (AMPKα1), AMPKα2, silent information regulator 1 (SIRT1) and PPARγ coactivator-1α (PGC1α), and reduced intestinal AMPKα phosphorylation. Collectively, these results indicate that Asn supplementation alleviates bacterial LPS-induced intestinal injury by modulating the AMPK signalling pathway and improving energy status.

Applying systems biology tools to study n‐butanol degradation in Pseudomonas putida KT2440

To smoothen the process of n‐butanol formation in Pseudomonas putida KT2440, detailed knowledge of the impact of this organic solvent on cell physiology and regulation is of outmost importance. Here, we conducted a detailed systems biology study to elucidate cellular responses at the metabolic, proteomic, and transcriptional level. Pseudomonas putida KT2440 was cultivated in multiple chemostat fermentations using n‐butanol either as sole carbon source or together with glucose. Pseudomonas putida KT2440 revealed maximum growth rates (μ) of 0.3 h−1 with n‐butanol as sole carbon source and of 0.4 h−1 using equal C‐molar amounts of glucose and n‐butanol. While C‐mole specific substrate consumption and biomass/substrate yields appeared equal at these growth conditions, the cellular physiology was found to be substantially different: adenylate energy charge levels of 0.85 were found when n‐butanol served as sole carbon source (similar to glucose as sole carbon source), but were reduced to 0.4 when n‐butanol was coconsumed at stable growth conditions. Furthermore, characteristic maintenance parameters changed with increasing n‐butanol consumption. 13C flux analysis revealed that central metabolism was split into a glucose‐fueled Entner–Doudoroff/pentose‐phosphate pathway and an n‐butanol‐fueled tricarboxylic acid cycle when both substrates were coconsumed. With the help of transcriptome and proteome analysis, the degradation pathway of n‐butanol could be unraveled, thus representing an important basis for rendering P. putida KT2440 from an n‐butanol consumer to a producer in future metabolic engineering studies.

Ralstonia solanacearum uses inorganic nitrogen metabolism for virulence, ATP production, and detoxification in the oxygen-limited host xylem environment.

ABSTRACTGenomic data predict that, in addition to oxygen, the bacterial plant pathogen Ralstonia solanacearum can use nitrate (NO3−), nitrite (NO2−), nitric oxide (NO), and nitrous oxide (N2O) as terminal electron acceptors (TEAs). Genes encoding inorganic nitrogen reduction were highly expressed during tomato bacterial wilt disease, when the pathogen grows in xylem vessels. Direct measurements found that tomato xylem fluid was low in oxygen, especially in plants infected by R. solanacearum. Xylem fluid contained ~25 mM NO3−, corresponding to R. solanacearum’s optimal NO3− concentration for anaerobic growth in vitro. We tested the hypothesis that R. solanacearum uses inorganic nitrogen species to respire and grow during pathogenesis by making deletion mutants that each lacked a step in nitrate respiration (ΔnarG), denitrification (ΔaniA, ΔnorB, and ΔnosZ), or NO detoxification (ΔhmpX). The ΔnarG, ΔaniA, and ΔnorB mutants grew poorly on NO3− compared to the wild type, and they had reduced adenylate energy charge levels under anaerobiosis. While NarG-dependent NO3− respiration directly enhanced growth, AniA-dependent NO2− reduction did not. NO2− and NO inhibited growth in culture, and their removal depended on denitrification and NO detoxification. Thus, NO3− acts as a TEA, but the resulting NO2− and NO likely do not. None of the mutants grew as well as the wild type in planta, and strains lacking AniA (NO2− reductase) or HmpX (NO detoxification) had reduced virulence on tomato. Thus, R. solanacearum exploits host NO3− to respire, grow, and cause disease. Degradation of NO2− and NO is also important for successful infection and depends on denitrification and NO detoxification systems.

Cold storage duration affects litchi fruit quality, membrane permeability, enzyme activities and energy charge during shelf time at ambient temperature

Storage and transport of litchi fruit at low temperature is widely practiced commercially. In this study, no pericarp browning was evident at out-turn on litchi fruit stored for 10 and 20 days at cold temperature of 3–5 °C, but fruit stored for 10 days at 3–5 °C gradually browned after 12 h of shelf time at ambient temperature of 25 °C, with the browning index (BI) being elevated to 2.5 at 24 h of shelf life. Furthermore, fruit stored for 30 days began to rot and had a decay incidence of about 30% after 24 h on the shelf. The temperature increment from 3–5 to 25 °C induced marked increases in activities of lipase, phospholipase D (PLD) and lipoxygenase (LOX). Litchi fruit stored for 10 days at 3–5 °C followed by the shelf time at 25 °C had lower activities of lipase, PLD and LOX, and also lower levels of membrane permeability, than did fruit stored for 20 and 30 days. Energy level of the pericarp tissue of cold-stored litchi fruit was similarly dependent on storage time at 3–5 °C plus shelf time at 25 °C. Adenosine triphosphate (ATP) content and adenylate energy charge (AEC) level in pericarp tissues decreased as cold storage progressed. However, ATP and adenosine diphosphate (ADP) contents, and the AEC levels, in cold-stored litchi fruit increased during shelf time at 25 °C, reaching a peak after 6 h, and then decreasing. Fruit stored for 30 days at 3–5 °C had much lower ATP content and AEC level than fruit stored for 10 and 20 days. Increased activities of lipase, PLD and LOX, and energy shortage in cold-stored pericarp tissues during subsequent shelf time at 25 °C suggest that the deterioration of membrane integrity and loss of compartmentation gives rise to accelerated browning and fruit quality deterioration.

Effect of capture method on the physiology and nucleotide breakdown products in the Norway lobster (Nephrops norvegicus)

The effects of capture method (creel and trawl) and trawling time (15, 60 and 150 min) were assessed in Norway lobsters by measuring stress-related metabolites together with nucleotide breakdown products. Furthermore, mechanical damage was scored in the animals captured by trawl. Capture method had a clear impact on the nucleotide profile in the Norway lobster muscle. In rested and creel-caught animals the main nucleotide was ATP, while in trawled animals the main nucleotide was AMP. According to these results the Adenylate Energy Charge (AEC) was lower in trawled animals compared with creel-caught animals, while trawling time did not affect AEC levels significantly. Stress-related and anaerobic metabolites together with muscle pH indicated that trawled animals, even at the shortest time tested, were using anaerobic metabolism. In the haemolymph, l-lactate increased with a delay compared with muscle, suggesting that the concentration of l-lactate in the muscle provides a more immediate measure of capture-stress in this species. Although physiological measures were similar for short and long tows, physical damage increased in long trawls. Further studies should elucidate whether the different physiological stresses and the physical damage that occur during capture could compromise the live transport of trawled animals, and if quality measures could thus be affected.

Regulation on Energy Metabolism and Protection on Mitochondria ofPanax GinsengPolysaccharide

Panax ginseng C A Meyer (PG) is one of the most popular qi-invigorating herbal medicine and has been used to promote health, vitality, and longevity in China. Although PG has been used in traditional Chinese medicine for millennia, its qi-invigorating activities still lack convincing evidence. We investigated the effects of Panax ginseng polysaccharide (PGP) on energy metabolism and mitochondrial protection. The chronic hypoxia model was set up. Lipid peroxidation product malondialdehyde (MDA) was assayed by thiobarbituric acid (TBA) colorimetry. Mice liver mitochondria were isolated by differential centrifugation. The spectrophotometric method was used to measure the swelling of mitochondria. The levels of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) in liver cells were determined by reversed-phase high performance liquid chromatography (RP-HPLC), adenylate energy charge (AEC), total adenylate pool (TAP), ATP/ADP and ATP/AMP ratio were calculated. The creatine kinase (CK) activities in mice skeletal muscle were determined by a commercial monitoring kit. The result showed that PGP could inhibit mitochondrial injury and swelling induced by Fe(2+)-L-Cys in a concentration-dependent manner. PGP which was administered by oral gavage daily for 10 days could inhibit the formation of MDA in mice brain, increase levels of ATP, ADP, TAP and AEC, ratio of ATP/ADP and ATP/AMP in liver cells, increase CK activities in mice skeletal muscle under chronic hypoxia condition. These results indicate that PGP protect mitochondria by inhibiting mitochondrial swelling, and improving energy metabolism. PGP functions as a preventive antioxidant by increasing CK activities. Therefore, PGP had the pharmaceutical activities of antihypoxia, antioxidation and improving energy status.

Short‐term anoxia treatment maintains tissue energy levels and membrane integrity and inhibits browning of harvested litchi fruit

AbstractPericarp browning is the main limitation to the postharvest storage, handling and marketing life of litchi fruit. Pre‐storage treatment with pure N2 gas is potentially effective in reducing skin browning and maintaining eating quality of litchis. To better understand inhibition of pericarp browning by a short period of anoxia, adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) levels, adenylate energy charge and membrane permeability were investigated. Litchi fruit were exposed to pure N2 gas for 6 h and then kept in closed but vented containers for 6 days in the dark at 25 °C and 95–100% relative humidity. Changes in the mentioned fruit physiology and biochemistry parameters and in browning index were measured. ATP concentration and adenylate energy charge decreased rapidly and membrane permeability (relative leakage) increased gradually during storage. Fruit exposed to N2 gas exhibited higher concentrations of ATP, ADP and AMP and adenylate energy charge levels, and lower levels of browning index and membrane permeability, compared to control (non‐N2‐treated) fruit. Greater differences in ATP and ADP concentrations and adenylate energy charge levels of pericarp tissues between N2‐treated and control fruit were more manifest after 4 and 6 days of storage, in association with significant differences at the 5% level in the pericarp browning index. It is suggested that pre‐storage anoxia treatment maintains membrane integrity of pericarp tissues, with high ATP and ADP concentrations and high adenylate energy charge levels. Thus, the loss of cellular compartmentalization (mixing of enzymes and substrates) that leads to enzymatic browning of litchi fruit pericarp is delayed. Copyright © 2007 Society of Chemical Industry

Impact of cycloheximide addition on adenylates in soil

Cycloheximide inhibits specifically the ribosomal protein synthesis of eukaryotic cells, i.e. the metabolism of soil fungi. We measured cycloheximide effects on adenylates in 20 different soils (0–10 cm depth) from arable, grass and forest land with a large variety of soil properties. The aims were (1) to assess the interactions between cycloheximide effects and soil properties and (2) to prove the relationship between cycloheximide effects on ATP and the ergosterol-to-microbial biomass C ratio, which is an indicator for the fungal proportion of the total microbial biomass. The adenylates ATP, ADP and AMP were measured 6 h after adding either 10 mg cycloheximide per gram soil in combination with 24 mg talcum per gram soil or 24 mg talcum per gram soil solely. The medians of the relative increases in AMP and ADP were 45 and 25% and the medians of the relative decreases in ATP and adenylates were −36 and −12%. These changes in adenylate composition lead to a cycloheximide-induced relative decrease in the adenylate energy charge level of 15%. The relative decrease in ATP content after cycloheximide addition was significantly correlated with the ATP-to-microbial biomass C ratio, but not with the ergosterol-to-microbial biomass C ratio. The absolute increase in ADP and the absolute decrease in ATP were affected by the clay content according to principal component analysis. The reduction of the ATP-to-microbial biomass C ratio indicates that this ratio had the potential of being an important ecotoxicological indicator of direct toxic effects of organic pollutants on soil microorganisms.

Soil biochemical and microbial indices in wet tropical forests: Effects of deforestation and cultivation

AbstractLittle information is available about the long‐term effects of deforestation and cultivation on biochemical and microbial properties in wet tropical forest soils. In this study, we evaluated the general and specific biochemical properties of soils under evergreen, semi‐evergreen, and moist deciduous forests and adjacent plantations of coconut, arecanut, and rubber, established by clear felling portions of these forests. We also examined the effects of change in land use on microbial indices and their interrelationships in soils.Significant differences between the sites occurred for the biochemical properties reflecting soil microbial activity. Microbial biomass C, biomass N, soil respiration, N mineralization capacity, ergosterol, levels of adenylates (ATP, AMP, ADP), and activities of dehydrogenase and catalase were, in general, significantly higher under the forests than under the plantations. Likewise, the activities of various hydrolytic enzymes such as acid phosphomonoesterase, phosphodiesterase, casein‐protease, BAA‐protease, β‐glucosidase, CM‐cellulase, invertase, urease, and arylsulfatase were significantly higher in the forest soils which suggested that deforestation and cultivation markedly reduced microbial activity, enzyme synthesis and accumulation due to decreased C turnover and nutrient availability. While the ratios of microbial biomass C : N and microbial biomass C : organic C did not vary significantly between the sites, the ratios of ergosterol : biomass C and ATP : biomass C, qCO2 and AEC (Adenylate Energy Charge) levels were significantly higher in the forest sites indicating high energy requirements of soil microbes at these sites.

Effects of Exogenous donor of nitric oxide - sodium nitroprusside on energy production of rat reticulocytes.

The effects of the sodium nitroprusside (SNP), a nitric oxide (NO) donor clinically used in the treatment of hypertensive emergencies on the energy production of rat reticulocytes were investigated. Rat reticulocyte-rich red blood cell suspensions were aerobically incubated without (control) or in the presence of different concentrations of SNP (0.1, 0.25, 0.5, 1.0 mM). SNP decreased total and coupled, but increased uncoupled oxygen consumption. This was accompanied by the stimulation of glycolysis, as measured by increased glucose consumption and lactate accumulation. Levels of all glycolytic intermediates indicate stimulation of hexokinase-phosphofructo kinase (HK-PFK), glyceraldehyde 3-phosphate dehydrogenase (GAPD) and pyruvate kinase (PK) activities in the presence of SNP. Due to the decrease of coupled oxygen consumption in the presence of SNP, ATP production via oxidative phosphorylation was significantly diminished. Simultaneous increase of glycolytic ATP production was not enough to provide constant ATP production. In addition, SNP significantly decreased ATP level, which was accompanied with increased ADP and AMP levels. However, the level of total adenine nucleotides was significantly lower, which was the consequence of increased catabolism of adenine nucleotides (increased hypoxanthine level). ATP/ADP ratio and adenylate energy charge level were significantly decreased. In conclusion, SNP induced inhibition of oxidative phosphorylation, stimulation of glycolysis, but depletion of total energy production in rat reticulocytes. These alterations were accompanied with instability of energy status.

Biochemical and behavioural effects of hydraulic dredging on the target species Chamelea gallina

This study is focused on evaluating biological effects on the target species Chamelea gallina as a result of repeated exploitation of clam beds by hydraulic dredging. A biomarker approach was adopted and two physiological indices were applied: adenylate energy charge (AEC) (biochemical level) and reburrowing behaviour (organism level). The aim was to investigate the biological response to various types of fishing, i.e., commercial systems using water at high pressures (HP), and experimental systems at lower pressures (LP) in the field, and to evaluate the response of clams to mechanical stress in the laboratory. Field results showed that HP-treated clams exhibited significantly lower levels of AEC compared with LP treatments. A similar trend was shown by reburrowing behaviour; HP-treated clams reburrowed less. Laboratory results were less clear: a very low level of AEC was measured in both control and treated clams. These poor conditions in foot muscle did not indicate worsening at organism level, as no dead or dying clams were recorded throughout the experiment. However, repeated mechanical stress reduced the percentage of reburrowing clams, which suggested that harvesting may affect reburrowing behaviour.

Energy Metabolism of Erythrocytes in Lambs Chronically Exposed to Fluorine Compounds

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Physiological response ofPectinatus frisingensis,a beer spoilage bacterium,to mild heat treatments

Genus Pectinatus is strictly anaerobic bacteria described as a new beer spoilage flora. The physiological response of Pectinatus frisingensis to increasing heat treatments has been studied. Cell death occurred at temperatures higher than 50°C and increased with time. During heat treatment at 50°C, a potassium efflux of more than 50% of the internal potassium was measured at pH 6.2 in starving bacteria, whereas a small transient potassium efflux was measured with a similar 50°C treatment in energized cell suspensions. At beer pH values (pH 4.0), potassium content of P. frisingensis cells was not changed by a moderate heat treatment. Internal pH values of cells were only slightly (0.1 pH unit) decreased upon heat treatments. In contrast, membrane potential value was lowered by a heat treatment at pH 6.2 in deenergized cells, while only a transient decrease of delta was measured with glucose in the medium. A moderate heat treatment at 50°C had no effect on the membrane potential value at pH 4.0, even after 1 h of treatment. In addition, compared with a high level of adenylate energy charge (AEC) measured in energized cell suspensions, an AEC of 0.7 was routinely measured in starving cell suspensions. Moderate heat treatments at pH 4.0 lowered the AEC of cells to 0.6. The physiological response of P. frisingensis to mild heat treatments demonstrated a significant ability of the cell to maintain internal homeostasis at pH conditions encountered in beer.Key words: Pectinatus, thermal death, beer spoilage, homeostasis.

Hepatic adenylate energy charge levels in patients with hepatoma after hepatic artery embolization.

AIM:To evaluate hepatic energy charge levels of the patients with hepatoma after hepatic artery embolization and its relation to postoperative complications.METHODS:Sixty-nine patients with hepatoma were continuously measured for their arterial blood ketone body ratio (AKBR) and compared with their postoperative clinical course or conventional liver function test after various hepatic artery embolization.RESULTS:AKBR in high radiation dose or jaundice group drastically decreased at 1-3 days and recovered slowly. Patients were classified into three groups according to the value of AKBR: group A (35 cases), AKBR remained higher than 0.7; group B (31 cases), AKBR had transiently dropped to 0.4-0.7 and then increased to preoperative value; and group C (3 cases), AKBR decreased steadily to below 0.4.The occurrence rate of various complications were 5.7%, 32.3% and 100% in the three groups, respectively (P < 0.005).CONCLUSION:The AKBR which reflects hepatic mitochondria redox state is more reliable as a direct indicator to assess hepatic tolerance for embolization than routine liver function test.

Time-related effects of intoxication with cadmium and mercury in the red wood ant

Biochemical and physiological effects of prolonged feeding of the ant Formica aquilonia, in natural conditions with excess of cadmium or mercury, were studied. In all developmental stages metals caused the time-dependent increase of AMP, parallel with a decrease of ATP and the pool size of adenylates. This was reflected by a low adenylate energy charge (AEC) index and accompanied by an inhibition of ATPases. Despite the fall in the adenylate pool of workers, the levels of adenylate energy charge confirmed their ability to maintain energetic balance. Prolonged access to food highly contaminated with Cd, or Cd with Hg, diminished these adaptive abilities, but pre-adaptive reactions (not correlated with the metal load) were induced. Activity patterns of enzymes involved in energy metabolism showed metal dependent inhibitory effects, but repeated contamination evoked some compensatory mechanisms, both in workers and in the pupal stage from the next generations. Cadmium (indirectly) stimulated the esterases and free radical scavengers. Compensatory mechanisms were insufficient in insects contaminated with both Hg and Cd, even causing family disappearance, through increased mortality and migration to other colonies. Compensatory mechanisms expressed by the adult workers appeared to be of a phenotypic origin

Effect of Storage Temperature on Stress Levels in Live Clams (Paphies donacina; tuatua)

Live New Zealand subtidal clams (Paphies donacina; tuatua) were stored in polyethylene-lined polystyrene boxes in an air chiller at 4oC and 0oC. Stress levels were monitored by measuring the accumulation of two glycolytic metabolites, D-lactate and octopine, and by measuring changes in adenylate energy charge (AEC). Tuatua mortalities were higher during storage at 0°C. Storage temperature affected the rate of D-lactate production and the ability to maintain AEC. D-lactate and/or AEC levels are useful indices of live quality during post harvest handling when product is stored out of sea water.

Expression of functional proteins of cDNA encoding rice nucleoside diphosphate kinase (NDK) in Escherichia coli and organ-related alteration of NDK activities during rice seed germination (Oryza sativa L.).

The GST (glutathione S-transferase)-NDK (nucleoside diphosphate kinase) fusion protein was expressed in Escherichia coli. The GST-NDK protein was capable of transferring gamma-phosphate from ATP to nucleoside diphosphates such as GDP, CDP, TDP and UDP. Western blot analysis using anti-NDK antibody indicated that NDK in endosperm gradually decreased during 36 h of imbibition. On the contrary, NDK in embryo increased during the same period. NDK activities in both tissues were in accord with these observations. Whereas the NDK protein in roots of rice seedlings during 7 days of imbibition remained constant, in shoots it declined after 5 days of imbibition. Thus, NDK may play a significant role in the cellular event modulated by adenylate energy charge level.