Respiratory Electron Transport System Research Articles

Measurement of the respiratory electron transport system (ETS) activity in marine sediments:state-of-the-art and interpretation. I. Methodology and review of literature data

Measurement of the respiratory electron transport system (ETS) activity in marine sediments:state-of-the-art and interpretation. I. Methodology and review of literature data

Measurement of the respiratory electron transport system (ETS) activity in marine sediments:state-of-the-art and interpretation. II. Significance of ETS activity data

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 136:289-301 (1996) - doi:10.3354/meps136289 Measurement of the respiratory electron transport system (ETS) activity in marine sediments: state-of-the-art and interpretation. II. Significance of ETS activity data Relexans JC The activity of the respiratory electron transport system (ETSA), measured in vitro in conditions of Vmax (i.e. with saturation of electron donors and acceptors), represents the respiratory potential of all communities sampled. From analysis of surface sediments from various oceanic areas, ETSA has been found to be correlated with the biopolymer (protein, carbohydrate, lipid) content which may represent the most labile fraction of the sedimentary organic matter. ETSA results expressed at constant temperature (e.g. 20*C) can be considered as an estimator of biomass, especially of the microbial biomass which contributes, in most cases, the greatest part of the sediment respiratory potential. Original and literature data reveal discrepancies between laboratory and field experiments, so that results obtained with cultured species cannot be directly applied to natural environments. A compromise conversion factor [particulate organic carbon (POC) biomass (ug) = ETS (ul O2 h-1) x 14.3] is proposed by the author. At in situ temperature, ETSA may theoretically be converted to respiration (R), which is the actual rate of electron transfer. The R/ETSA ratio used for conversion depends strongly on the availability of food. This ratio decreases from coastal to deep areas but results show that the gradient (from 0.4 in shallow sediments to 0.05 in deep sea areas, on average) is not as steep as previously thought. Due to the lack of accuracy of the R/ETSA ratio, the use of ETSA to calculate sediment community oxygen consumption is not very promising and direct measurements of respiration are preferable. Finally, it is concluded that the most important application of the ETSA measurement in sediments is its use as an estimator of the total microbial biomass. ETS activity in sediments Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 136. Publication date: June 06, 1996 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1996 Inter-Research.

Respiratory electron transport system (ETS)-activity of the plankton and biofilm in the high-mountain lake La Caldera (Sierra Nevada, Spain)

Quantity and ETS-activity of the plankton and those of the biofilm in the high-mountain lake La Caldera (altitude: 3040 m a.s.l.) were studied in August-September, 1992 and 1993. The quantity of the biofilm, covering the bed stones sometimes reached 1 kg wet mass m -2 . Its ETS-activity exceeded by 2.5-5 times, that of the phytoplankton and, by 8.33-22 times, that of the zooplankton, projecting 1 m 2 surface area of the lake. The substrate kinetics of its ETS suggested eucaryotic property. The plankton concentrated in the deeper water in day time and elevated to the upper water layers by evenings. The daily respiratory carbon loss of the zooplankton, estimated from the ETS-activity was equivalent with 34-38 % of the planktonic primary production. The results indicated that the metabolically most active zone was forced to the profound, probably by the intensive UV-b radiation.

Toxic effect of the mosquito killer, S‐Deltamethrine, on the development and respiratory electron transport system activity of the embryos of bream (Abramis brama L.), roach (Rutilus rutilus), barbell (Barbus barbus) and pike (Esox lucius)

AbstractThe effect of the insecticide, S‐Deltamethrine (DM, LC50 for mosquito larvae: 0.02 ppb), in the concentration range between 0.025 and 2500 ppb was examined in both embryogenesis and embryonic evolution of the electron transport system (ETS) of the bream, roach, barbel and pike. A 0.025 ppb concentration of DM caused 10‐25% death of the embryos in the first 2 days of incubation.Fifty per cent of the roach embryos died by the end of a 144 h incubation period when the concentration was 0.025 ppb. In 2.5 ppb, 50% of the embryos died after 120 h. In 25 ppb, 50% death was registered after 96 h, and in 250 and 2500 ppb, 50% death was detected after 48 h. Fifty per cent of the barbel embryos died after a 48 h long incubation time in 250 and 2500 ppb. The same mortality was detected for the embryos of pike in 2500 ppb after a longer (148 and 168 h) incubation time. Half of the bream embryos died after 24 and 48 h at a concentration of 2500 ppb. Larvae showed a more sensitive response to treatments than did embryos. After hatching, 30‐84% of the larvae died in 0.025 ppb. Compared to embryos, larvae moved less in a concentration of 0.025 ppb and could not swim as easily as controls. In a concentration >0.25‐2.5 ppb, larvae were passive and often malformed. S‐Deltamethrine inhibited ETS activity in a concentration‐dependent manner. Electron transport system activity of larvae was reduced by 50% in 250 ppb concentration.

The Copper-containing Dissimilatory Nitrite Reductase Involved in the Denitrifying System of the Fungus Fusarium oxysporum

A copper-containing nitrite reductase (Cu-NiR) was purified to homogeneity from the denitrifying fungus Fusarium oxysporum. The enzyme seemed to consist of two subunits with almost the same M(r) value of 41,800 and contains two atoms of copper per subunit. The electron paramagnetic resonance spectrum showed that both type 1 and type 2 copper centers are present in the protein, whereas the visible absorption spectrum exhibited a sole and strong absorption maximum at 595 nm, causing a blue but not green color. The reaction product due to the Cu-NiR was mainly nitric oxide (NO), whereas a stoichiometric amount of nitrous oxide (N2O) was formed when cytochrome P-450nor was further added to the assay system. Therefore, the denitrifying (N2O forming) nitrite reductase activity that we had detected in the cell-free extract of the denitrifying cells (Shoun, H., and Tanimoto, T. (1991) J. Biol. Chem. 266, 11078-11082) could be reconstituted upon combination of the purified Cu-NiR and P-450nor. The Km for nitrite and specific activity at pH 7.0 were estimated as 49 microM and 447 mumol NO.min-1.mg protein-1, respectively. Its activity was strongly inhibited by cyanide, carbon monoxide, and diethyldithiocarbamate, whereas enormously restored by the addition of cupric ions. An azurin-like blue copper protein (M(r) = 15,000) and a cytochrome c were also isolated from the same fungus, both of which together with cytochrome c of the yeast Saccharomyces cerevisiae were effective in donating electrons to the fungal Cu-NiR. The result suggested that the physiological electron donor of the Cu-NiR is the respiratory electron transport system. The intracellular localization of Cu-NiR was investigated, and it was suggested that the Cu-NiR localizes in an organelle such as mitochondrion. These findings showed the identity in many aspects between the fungal nitrite reductase and bacterial dissimilatory Cu-NiRs. This is the first isolation of dissimilatory NiR from a eukaryote.

Respiratory electron transport system (ETS) activity in Spanish reservoirs: relationships with nutrients and seston

We examined the relationship between potential respiration rates, as measured by electron transport system (ETS) activity, standardized at a defined temperature (ETS2O). and nutrients and sestonic particles in a set of 101 Spanish reservoirs spannin a wide range of limnological characteristics. ETS activity ranged from 0.009 to 31 31 μmol e- 1−1 h−1 Among the nutrients, it was significantly correlated only with phosphorus, and only during the stratification period. During this period, the best regressor of ETS2O was the concentration of chlorophyll a (Chla), whereas during the mixing period the best regressor was particulate organic nitrogen (PON), suggesting a greater contribution of non-algal sestonic particles to total metabolism. Both the mean ETS20:PON ratio and the mean Chla:PON ratio increased systematically with increasing PON, indicating a lower relative contnbution of detrital particles to total seston as trophic state increased. In contrast, the mean ETS20:Chla ratio was constant across the range of Chla. Vertical profiles of ETS2O. Chla and PON were more coherent during the stratification period. when subsurface and metalimnetic peaks were frequent, than during the mixing period.

Respiration and biochemical composition of sedimenting organic matter during summer in the Barents Sea

Sedimentation of particulate carbon and nitrogen, pigments (fluorometric and HPLC analysis) as well as the activity of the respiratory electron transport system in sedimented matter were studied with unpoisoned, short-term deployed sediment traps during June in the central Barents Sea. The vertical flux of sedimenting material and its biochemical composition in the central Barents Sea was different during summer compared to spring with decreased flux of organic matter and decreased relative supplies of particulate nitrogen, but increased phaeopigment concentrations. The summer situation in the Barents Sea is characterized by recycling of the bulk of the suspended matter in the upper layers, a comparatively small loss of suspended biomass, but high sinking rates of some few, large particles, presumed to be faecal pellets. Respiration calculated as a daily loss rate of carbon in the sedimented material was on average only 1.4% day −1. Loss was strongly temperature dependent. At in situ temperatures 5°C, it is necessary to estimate turnover rates for sedimenting carbon in non-poisoned traps for an accurate elemental budget of a system and for interpretation of estimates from long-term trap deployments.

Change in the activity of the respiratory electron transport system in natural phytoplankton assemblages and cultured algae

Activities of the respiratory electron transport system (ETS),14C uptake, chlorophyll and temperature were determined at a station in the center of Donghu Lake. Seasonal fluctuations in ETS-activities ranged from 100 to 460 μg O2 h−1 · L−1. Production: respiration ratio (P/R) calculated from C uptake and ETS-activity, ranged from 0.2 to 6.8. The test on cultured algae ETS-activity revealed marked differences in different growth phases. ETS activity is suggested as an indicator of lake nutrient status.

Metabolic Rates in Early Life History Stages of Elopomorph Fishes.

The respiratory electron transport system (ETS) assay was used to estimate metabolic rates in four species of eel (Anguilliformes: Ophichthidae and Congridae) leptocephali (Myrophis punctatus, Ophichthus sp., Hildebrandia flava, and one unidentified congrid) and the bonefish (Albuliformes: Albulidae: Albula sp.). Wet-weight-specific ETS values in whole-body homogenates, assayed at physiological temperatures, ranged from 4-20 {mu}-at O h-1 (g wet wt)-1. Arrhenius activation energies (Ea) ranged from 11.0-15.7 kcal mole-1. Both wet-weight-specific ETS activity and oxygen consumption rate increased approximately fivefold during metamorphosis of leptocephali of Albula sp. Wet-weight-specific ETS activity showed little change as leptocephali of M. punctatus transformed into glass eels, but increased about fivefold as glass eels metamorphosed into elvers. No significant difference was found in ETS activity measured in fresh early metamorphic leptocephali of Albula sp. and leptocephali that had been stored frozen at -70{deg}C for up to 15 months. The data suggest that metabolic rates are low in leptocephali, which implies that the demand for nutrients is also relatively low. We argue that the apparent diet of these larvae seems capable of providing a sufficient supply of nutrients under these conditions.

An intermediate nepheloid layer associated with high microbial metabolic rates and denitrification in the northwest Indian Ocean

Extensive optical, physical, chemical, and biochemical measurements made simultaneously in the northwest Indian Ocean reveal the occurrence of an intermediate nepheloid layer (INL) invariably associated with the secondary nitrite maximum. Maxima in particulate protein and the activity of the respiratory electron transport system (ETS) are also found within the INL. Since the INL persists long distances from the continental margin with an offshore intensification, it may not be related to the transport of material resuspended along the continental margin. An apparent correlation of the INL with the previously reported subsurface maximum in bacterial abundance suggests that a local increase in the abundance of bacteria may be responsible for the increased turbidity. Positive correlations of the beam attenuation anomaly with nitrite and nitrate deficit suggest that most of these bacteria may be denitrifiers. The organic carbon demand within the denitrifying layer, computed from the observed ETS activity, appears to be severalfold higher than the sinking carbon fluxes to the denitrifying layer, requiring additional modes of supply of the biodegradable organic matter. It is proposed that a bacterial maximum could be maintained with efficient utilization of the dissolved organic matter within the denitrifying waters.

N-n-alkyl-3,4-dihydroxybenzamides as inhibitors of the trypanosome alternative oxidase: activity in vitro and in vivo.

On the basis of our previous demonstration of the high inhibitory activity of a series of p-n-alkyloxybenzhydroxamic acids and n-alkyl esters of 3,4-dihydroxybenzoic acid against the trypanosome alternative oxidase in a cell-free mitochondrial preparation of Trypanosoma brucei brucei, we synthesized a series of N-n-alkyl-3,4-dihydroxybenzamides for evaluation as inhibitors of this enzyme. This class of compounds was selected with the expectation of their having similar inhibitory activity to but greater solubility than the esters and hydroxamic acids noted above and greater resistance to serum hydrolases in vivo. We predicted that such properties would allow an inhibitor of the trypanosome alternative oxidase to be coadministered with glycerol as a means of providing treatment for infections by African trypanosomes. As expected, such benzamides were both more soluble and more stable, some being more active against the target enzyme than the corresponding ester. One, N-n-butyl-3,4-dihydroxybenzamide, was selected for evaluation in vivo against T. brucei brucei. When combined with glycerol, this benzamide was found to be curative. A regimen wherein 450 mg of N-n-butyl-3,4-dihydroxybenzamide per kg and 15 g of glycerol per kg were given hourly in three divided doses cured 17 of 19 mice with established T. brucei brucei infections. This combination is more active in vivo than any other designed to block simultaneously both the unique respiratory electron transport system and the anaerobic glycolytic pathways of these pathogenic protozoa.

Activity of the respiratory electron transport system and respiration rates within the oxygen minimum layer of the Arabian Sea

Abstract Measurements of the activity of the respiratory electron transport system (ETS) at 15 stations in the Arabian Sea during the northeast monsoon (December 1988) yield high respiration rates that do not correlate with the trends in primary productivity. The rates are unlikely to be sustained by the supply of carbon associated with the sinking particles alone, and seem to suggest a major role for dissolved and/or suspended organic matter in fuelling oxygen consumption and denitrification. The data are utilized to compute a denitrification rate of 24–33 Tg N y−1 in the Arabian Sea. This estimate agrees with the estimate based on the exports of nitrate deficits outside the denitrification zone. The ventilation time of the denitrifying layer is calculated as ∼1 year.

Deleterious effects of disulfiram on the respiratory electron transport system of liver mitochondria

1. 1. The mechanism of action of disulfiram on the respiratory electron transport system of the liver mitochondria was studied in vitro. 2. 2. Disulfiram inhibited the respiration supported by malate-glutamate as well as succinate. 3. 3. Mitochondrial respiration inhibition was dependent upon alteration of —SH groups. 4. 4. The inhibitory action of disulfiram might be related to the crosslinking of several proteins of the inner mitochondrial membrane. 5. 5. The effects described above could be attributed to disulfiram per se and not to the main metabolite diethyldithiocarbamate.

Respiratory electron transport system (ETS) ? activity of the plankton and sediment in Lake Balaton (Hungary)

Respiratory electron transport system (ETS) ? activity of the plankton and sediment in Lake Balaton (Hungary)

Benthic respiratory potential with relation to sedimentary carbon quality in seagrass beds and oyster parks in the tidal flats of Arcachon Bay, France

Relationships between sedimentary organic carbon quality and the benthic response were checked in tidal sediment of Arcachon Bay, France. Pigment and easily extractable macromolecular contents were used as indicators of the quality of particulate organic carbon (POC) while respiratory electron transport system (ETS) activity was chosen as an indicator for benthic response. The study was carried out in seven stations representing strongly different facies; these stations were sampled seasonally. Total ETS-activity includes the respiratory potential of various benthic compartments (phytobenthos, meiofauna, protozoa and bacteria). The importance of each of these components was calculated using conversion factors between ETS and biomass parameters. It was shown that ETS-activity due to phytobenthos was relatively high (up to 87% of total ETS) in stations under intense hydrodynamic conditions, but low (less than 23%) in the most sheltered stations. The impact of meiofauna was very low in all stations (less than 15% of heterotrophic ETS). Total and heterotrophic ETS activities were highly correlated with either POC, macromolecular content or protein. The slopes of the curves were compared with the ratios known for living organisms. The ETS/POC ratio in sediment was much lower than that in living matter while ETS/macromolecules and especially ETS/protein in sediment were of the same order as that in living material. We conclude that the degradable organic matter, (i.e. easily extractable biopolymers) could be mainly biomass and that detrital degradable molecules could be rapidly incorporated in biomass and not accumulate.

Biomass and respiratory ETS activity of microplankton in the Barents Sea

The activity of the respiratory electron transport system (ETS) of microplankton was measured in the Central Barents Sea during summer 1988. In vitro ETS activity increased with assay temperature between 0 and 2°C, as reported for other enzyme systems in plankton. The higher in situ activities were observed near the surface (upper 10-25 m) and were associated with chlorophyll a maxima. Respiratory activity in the upper 60 m accounted for 40-60% of the total column respiration. The activities (0-100 m) were lower than oxygen consumption rates reported in the Canadian Arctic, mainly due to lower phytoplankton biomass. They were higher than ETS activity measured in the Weddell Sea (Antarctic Ocean). A high detrital versus total microplankton mass accounted for the low activity related to particulate organic carbon (POC). In general, the levels of respiratory ETS activity were in the range reported for temperate oligotrophic oceanic regions.

Influence of temperature on respiratory ETS-activity of micro-organisms from Admiralty Bay, King George Island, Antarctica

This study describes the respiratory ETS-activity of surface water in an Antarctic coastal area and analyses the effect of temperature on the ETS-activity of organisms living in a consistently low-temperature regime. Secchi disk visibility, temperature, particulate ATP, respiratory electron-transport-system (ETS) activity and bacterial numbers were estimated at ten stations, nine in Admiralty Bay and one off the coast of King George Island in Bransfield Strait in December 1990 and in January 1991. Admiralty Bay was not ice-free in December. Here lower bacterial numbers, ATP and ETS-activities and higher visibilities were found than at the Bransfield Strait station. The lower visibility and higher biomass values and respiration activities in Bransfield Strait can be explained by an earlier start of the primary production in the Strait than in the Bay. In the Bay, at some stations low visibility was not correlated with high values of biomass or activity; the turbidity was caused by material imported from the land to the Bay by meltwater from the ice and snow. In the Bay, the respiratory ETS activity at substrate saturation of the surface layers varied between 6 and 13 μg C·dm −3·d −1 in December and between 5 and 14 μg C·dm −3·d −1 in January, while in Bransfield Strait the values for December and January were 54 and 17 μg C·dm −3·d −1, respectively. The effect of temperature on the respiration activity of the microbial ecosystem of Admiralty Bay (King George Island, Antarctica) was investigated. The temperature optimum of the respiration activity was between 20 and 25°C, and the activation energy calculated from the Arrhenius curve was 75 KJ·mol −1 (=18 Kcal·mol −1), i.e. a strong response to small temperature changes.

Chlorophyll a and respiratory electron transport system activity in microplankton from the surface waters of the western Mediterranean

The distribution of microplankton biomass and the metabolism of surface waters in the western Mediterranean are shown to be strongly associated with the circulation. Chlorophyll a and respiratory electron transport system (ETS) activity of microplankton were measured in surface waters during the Western Mediterranean Circulation Experiment in May and June 1986. Biological signatures, defined by satellite and surface ship measurements, defined complex circulation patterns of surface waters between the Alboran Basin and the Straits of Sicily. Close correlation was found between the distribution of in situ measured surface chlorophyll, ETS activity, ETS/Chl ratio (chlorophyll‐specific ETS activity), salinity, and temperature with satellite‐derived chlorophyll and surface temperature. High ETS/Chl ratios were found located in frontal regions of the Algerian Current and encircling a large anticyclonic eddy. Statistical correlations were performed on in situ and synoptic satellite data. Results show positive correlation between chlorophyll and ETS activity and ETS/Chl ratio and temperature. Excellent correlations were found between in situ chlorophyll and chlorophyll derived from the coastal zone color scanner. Improved statistical correlations were observed by separation of the surface waters based on their salinity into Modified Atlantic Water (MAW) (S < 37) and Mediterranean surface waters (S > 37). MAW with higher chlorophyll and metabolic activity is shown to characterize the circulation of the Algerian Current. The differences in the statistical correlations of these water masses indicate that regional circulation significantly influences the biological functions of microplankton populations.

The importance of self-oxidation in decomposition and its dependence on the pH of the environment

The aim of this work is to introduce and to test the hypothesis that pH-dependent self-oxidation of dead organic matter by its own respiratory electron transport system /ETS/ can be an important alternative process to active decomposition by microorganisms. An important event of the pH-dependent self-oxidation is the opening of cell walls and envelopes of decaying cells providing free opportunity for equilibration the internal and external pH.

Respiratory electron transport system activity as a measure of the effect of toxicants on a natural freshwater phytoplankton community.

Respiratory electron transport system activity as a measure of the effect of toxicants on a natural freshwater phytoplankton community.