A note on eggshell porosity,nest humidity and the effects of DDE in the grey heron (Ardea cinerea)

• 1.1. Water vapour conductance (G_H2O) was determined for 25 grey heron Ardea cinerea eggs in the laboratory, and in nests during natural incubation at two Scottish colonies.
• 2.2. The mean G_H2O of eggs measured in the nest which successfully hatched was 9.0 mgH;O/mmHg/day and the mean water vapour pressure gradient between egg and nest (ΔP_H2O), measured using “calibrated” duck eggs, averaged at 31 mmHg (4.13 kPa).
• 3.3. Based on eggshell porosity results, from the eggs which hatched, such a gradient would result in a loss of water from the eggs during incubation equivalent to 11% of their fresh weight.
• 4.4. Shell thickness, the number of pores/cm² of eggshell and DDE content were also determined for the 25 eggs measured in the laboratory.
• 5.5. Eggs containing high levels of DDE had thinner shells, more pores in the eggshell and a higher overall eggshell porosity.
• 6.6. The main problem posed by a high level of DDE would appear, however, not to be an excessive water loss from the egg during incubation, but rather eggshell thinning leading to a loss of the egg due to breakage in the nest.

     

In vivo administration of H2 blockers,cimetidine and ranitidine,reduced the contents of the cytochrome P450IID (CYP2D) subfamily and their activities in rat liver microsomes

• 1.1. The effects of in vivo administration of H₂ blockers, cimetidine and ranitidine (0.6 mmol/kg body weight/day, for 5 days), on several P450 isozymes, the P450IID (CYP2D) subfamily, and their monooxygenase activities in rat liver microsomes were investigated.
• 2.2. In vivo administration of cimetidine and ranitidine decreased the contents of P450 isozymes and the activities of P450-linked monooxygenase systems; i.e., benzphetamine N-demethylase, aminopyrine N-demethylase, 7-ethoxycoumarine O-deethylase, debrisoquine 4-hydroxylase and bufuralol 1'-hydroxylase.
• 3.3. The inhibitory effect on the enzymatic activities of the P450IID (CYP2D)-linked monooxygenase systems was studied by Western blot analysis with serum containing antiCYP2D6 IgG, i.e., LKM1 autoantibody. The amount of P450IID (CYP2D) in liver microsomes decreased more remarkably in the group administered ranitidine or cimetidine in vivo than in controls.
• 4.4. The effects of cimetidine and ranitidine on the activities of the P450IID (CYP2D)-linked monooxygenase systems were investigated in vitro. The activities of debrisoquine 4-hydroxylase and bufuralol 1'-hydroxylase were inhibited in vitro by cimetidine or ranitidine at a higher concentration than that on in vivo administration of either H₂ blocker.
• 5.5. The kinetic parameters for cimetidine or ranitidine as to the activities of debrisoquine 4-hydroxylase and bufuralol 1'-hydroxylase in liver microsomes were determined by means of Lineweaver-Burk plots.
• 6.6. The suppressive effects of cimetidine and ranitidine on the activities of the P450IID (CYP2D)-linked monooxygenase systems in vivo were found to be due to a decrease of the content of the P450IID (CYP2D) protein.

     

Temperature shift-induced changes in the antioxidant enzyme system of Cyanobacterium synechocystis PCC 6803

• 1.1. Effect of controlled up- and down-shifts of growth temperature on the antioxidant enzymes activities and lipid peroxidation were investigated in intact cells of Cyanobacterium synechocystis PCC 6803 acclimated at different growth temperature.
• 2.2. Algal cells grown at 36°C were treated at 20 and 43°C as down- and upward-shifts of growth temperature for 24 hr, respectively. At the down-shift of growth temperature the superoxide dismutase, catalase and glutathione peroxidase were significantly increased with concomitant decrease in protein content.
• 3.3. These parameters showed similar temperature dependencies in the up-shift of growth temperature, they were decreased significantly.
• 4.4. The increased hydroxyl (HO) radical and malonyldialdehyde (MDA) formation, when algal cells exposed to down-shift of growth temperature, supposedly due to stimulated production of superoxide radicals (O₂⁻) and hydrogen peroxide (H₂O₂) at lower temperature.

     

Metabolic responses of Cassin's Finches (Carpodacus cassinii) to temperature

• 1.1. The thermal neutral zone of Cassin's Finches extends from 22 to 37.5°C.
• 2.2. Standard metabolism (40.1 Wm⁻² or 7.6kcal bird⁻¹ day⁻¹) of the 28 g birds was 89% of the value predicted for passerines measured at night.
• 3.3. At temperatures below the zone of thermal neutrality metabolism is described by the relation, Wm⁻² = 1.55–74.5°C. The coefficient of heat transfer (1.55Wm⁻²°C⁻¹) is only 58% of the value predicted for birds of this size, indicating excellent insulation.
• 4.4. At temperatures above thermal neutralzfsity metabolism is described by the relation, Wm⁻² = 2.75–62.6°C.
• 5.5. Under conditions of heat stress (44.5°C; P_H2O = 8.6 Torr) Cassin's Finches were able to dissipate up to 208% of their metabolic heat production by evaporative water loss. Maximal rate of water loss was 56 mg g⁻¹ hr⁻¹.
• 6.6. At 20°C resting fasted finches lost a mean of 4.94 ± 1.5 SD mg H₂O g⁻¹hr⁻¹.

     

Electron transport in sheep (Ovis aries) liver microsomes. Characteristics,effect of lipid peroxidation and aqueous acetone extraction

• 1.1. Activities and contents of the electron transport components of sheep (Ovis aries) liver microsomes are given. Enzymes or enzyme systems assayed are NADH-cytochrome c reductase, NADH-ferrieyanide reductase, NADH-dichlorophenol-indophenol reductase, NADH- and NADPH-neotetrazolium reductase, cytochrome b₅, cytochrome P-450 and the cyanide binding protein.
• 2.2. Prior lipid peroxidation of sheep liver microsomes did not markedly alter NADH- and NADPH-cytochrome c reductase or NADH-ferricyanide reductase activities but decreased NADPH-dependent aniline hydroxylation activity. Intermediate amounts of prior lipid peroxidation enhanced the activity of NADPH-dependent lipid peroxidation.
• 3.3. NADH-cytochrome c reductase activity of sheep liver microsomes was decreased 39–56% when 60% of the microsomal organic phosphorus was removed by acetone:water 90:10 (v/v) extraction but was not markedly altered by the removal of 25 and 44% of the microsomal organic phosphorus by acetone:water 100:4 (v/v) and acetone:water 100:7 (v/v) extractions.

     

O2-binding by the blood of the landhopper,Arcitalitrus dorrieni (Hunt) (Crustacea: Amphipoda)

• 1.1. The O₂-binding characteristics of the blood of the euterrestrial amphipod (landhopper) Arcitalitrus dorrieni have been studied.
• 2.2. The blood exhibited a low O₂ affinity, with a p₅₀ (at pH = 7.8) of 21.4 torr (10°C). Affinity decreased with an increase in temperature at constant pH (ΔH = − 79.4kJ/mol) but the Bohr factor (ΔlogP₅₀/Δ pH = −0.67) was unaffected.
• 3.3. The O₂-carrying capacity of the blood was moderate (1.51 ml/100 ml)
• 4.4. The results support the hypothesis that the blood of terrestrial amphipods is characterized by having a low affinity pigment.

     

Stimulatory effects of lung cytochrome b5 on benzphetamine N-demethylation in a reconstituted system containing lung cytochrome P450 LgM2

• 1.1. Cytochrome b5 was partially purified from sheep lung microsomes in the presence of detergents Emuigen 913 and cholate by three consecutive DEAE-cellulose and Sephadex G-100 gel filtration chromatographies.
• 2.2. The specific content ofcytochrome b5 was 16.5 nmol/mg protein and purified cytochrome b5 fractions were free of cytochrome P450, NADPH-cytochrome P450 reductase and NADH-cytochrome b5 reductase activities.
• 3.3. The influences of increasing concentrations of lung cytochrome b5 on benzphetamine N-demethylation reactions were examined in four different reconstitution systems containing lung cytochrome P 450 LgM2, lung cytochrome P450 reductase and lipid. In each system concentration of reductase was doubled with respect to former system.
• 4.4. In all systems cytochrome b 5 stimulated benzphetamine Ndemethylase activity especially when cytochrome b5 was present at 0.5:1 molar ratio with respect to cytochrome /P450 LgM2.
• 5.5. Besides, the greatest fold of increase in benzphetamine N-demethylation activity due to addition of cytochrome b5 was observed in System 1 with the lowest concentration of reductase.

     

IDentification of a microsomal retinoic acid synthase as a microsomal cytochrome P-450-linked monooxygenase system

• 1.1. To characterize an enzyme which metabolizes retinal in liver microsomes, several properties of the enzymatic reaction from retinal to retinoic acid were investigated using rabbit liver microsomes.
• 2.2. The maximum pH of the reaction in the liver microsomes was 7.6.
• 3.3. The K_m and V_max values for all-trans, 9-cis and 13-cis-retinals were determined.
• 4.4. The reaction proceeded in the presence of NADPH and molecular oxygen.
• 5.5. The incorporation of one atom of molecular oxygen into retinal was confirmed by using oxygen-18, showing that the reaction comprised monooxygenation, not dehydrogenation.
• 6.6. The monooxygenase activity was inhibited by carbon monoxide, phenylisocyanide and antiNADPH-cytochrome P-450 reductase IgG, but not by anti-cytochrome b₅ IgG.
• 7.7. The enzymatic activity inhibited by carbon monoxide was photoreversibly restored by light of a wavelength of around 450 nm.
• 8.8. The retinal-induced spectra of liver microsomes with three isomeric retinals were type I spectra.
• 9.9. The microsomal monooxygenase activity induced by phenobarbital or ethanol were more effective than that by 3-methylcholanthrene, clotrimazole or β-naphthoflavone.
• 10.10. These results showed that the monooxygenase reaction from retinal to retinoic acid in liver microsomes is catalyzed by a cytochrome P-450-linked monooxygenase system.

     

Properties of ferredoxin reductase and ferredoxin from the bovine corpus luteum

• 1.1. Ferredoxin reductase and ferredoxin were purified from the bovine corpus luteum and their properties compared to the corresponding adrenal proteins.
• 2.2. The luteal and adrenal proteins had similar absorbance spectra and molecular weights.
• 3.3. Evidence was obtained from spectrophotometric titrations for formation of 1:1 complexes between luteal ferredoxin reductase and ferredoxin and between ferredoxin and cytochrome P-450_scc.
• 4.4. Adrenal ferredoxin reductase and ferredoxin were equally as effective as luteal ferredoxin reductase and ferredoxin in supporting cholesterol side-chain cleavage by luteal cytochrome P-450_scc.

     

Factors affecting oxygen consumption in wild-caught yellow-bellied marmots (Marmota flaviventris)

• 1.1. All age groups gained mass during the active season, but mass-gain of adult females was delayed during lactation.
• 2.2. The relationship of body mass to metabolic rate varied widely; when the relationship was significant, R² varied from 10.3 to 72.6%. Body mass affects V_O2 more during lactation than at any other period.
• 3.3. Mean VinO₂ of adult males was higher in June than that of adult, non-lactating females.
• 4.4. V_O2 of reproductive females was significantly higher during lactation than during gestation or postlactation because specific V_O2 varied. Specific V_O2 of non-reproductive females declined over the active season.
• 5.5. Specific V_O2 of all age groups declined between the premolt and postmolt periods. The reduced maintenance costs can contribute 20–46% to daily growth.
• 6.6. Observed V_O2 was lower than the value predicted from intraspecific or interspecific Bm:M regressions.
• 7.7. V_O2 of wild-caught marmots was lower than that of marmots maintained in the laboratory, probably because of dietary differences.
• 8.8. Because basal metabolism is a stage on a food-deprivation curve, we suggest that basal metabolic rate is not an appropriate measure of the metabolic activity of free-ranging animals.

     

Effects of inhibition of nadph: cytochrome p-450 reductase on benzo(a)pyrene metabolism in mouse liver microsomes

• 1.1. Effects of antioxidants (butylated hydroxytoluene and nor-dihydroguaiaretic acid), vitamin K-related quinones (vitamin K₁ and coenzyme Q₁₀) and inorganic copper (CuSO₄), in concentrations inhibiting NADPH: cytochrome P -450 reductase, were re-examined on benzo(a)pyrene metabolism in mouse liver uninduced microsomes.
• 2.2. It was found that all these compounds decrease production of the two-electron oxygenation products of benzo(a)pyrene (monophenoles, diols) and the amounts of glucuronides in a manner parallel to their inhibitory potency against NADPH: cytochrome P-450 reductase.
• 3.3. No correlation was found between amounts of one-electron oxidation products of benzo(a)pyrene and inhibition of NADPH: cytochrome P-450 reductase.
• 4.4. Without added UDPGA the compounds studied decreased protein associated benzo(a)pyrene metabolites in parallel to the decreased overall metabolism of this polyaromatic hydrocarbon.
• 5.5. The mode of action of the studied compounds is discussed.

     

Hen's egg yolk alkaline phosphatase: General characterization and kinetic stuy with inhibitors

• 1.1. The non-specific hen's egg yolk alkaline phosphatase is a metalloprotein (Zn²⁺?) composed of two identical inactive subunits.
• 2.2. A second metal site preferably binds Mg²⁺ (15-fold activation). Me(II))H₂O)H⁺, a charged arginine, and tyrosine in the active site are involved in positioning and binding of the substrate and metal ion.
• 3.3. Substrate inhibition differs with pH. This may be related to the presence of two active sites in the enzyme, one in each subunit.
• 4.4. Uncompetitive inhibition with L-phenylalanine and analogues suggests a phosphorylated intermediate.
• 5.5. Inhibition is weakly competitive with P_i strong non-competitive with PPi as compared to Mg²⁺-free PP_i, and partially competitive with arsenate.
• 6.6. The purified enzyme is stabilized and activated by amines and proteins.

     

Biomines-stimulated phosphorylation and (Na+, K+-ATPase in the gills of the chinese crab,Eriocheir sinensis

• 1.1. Subcellular distribution of (NA⁺, K⁺-ATPase and ouabain-insensitive ATPase (Mg²⁺-ATPase) are compared in branchial tissues of the euryhaline crab, Eriocheir sinensis, acclimated to fresh water.
• 2.2. Both the anterior and posterior gills contain cAMP-dependent protein kinase and endogenous protein substrate for phosphorylation.
• 3.3. Phosphorylation occurs in both “particulate” and “soluble” subcellular fractions but its stimulation by cAMP is restricted to the “soluble” fraction.
• 4.4. serotonin (5-HT) and dopamine receptors are present only in the “light particulate” fraction isolated from the posterior gills.

• 1.(a) Serotonin and dopamine have no effect on the phosphorylation observed in a subcellular fraction alone.
• 2.(b) Activation of the phosphorylation by serotonin and dopamine is found when the soluble fraction (source of cAMP-dependent protein kinase) is added to the fraction P₃ from the posterior gills.
• 3.(c) No activation occurs with the fractions P₃ as well as P₁ or P₂ (not shown) from anterior gills of fresh water crab.
• 4.(d) Cyproheptadine, a serotonin receptor antagonist, inhibits the 5-HT dependent increase in phosphorylation.
• 5.(e) The dopamine receptor antagonist, chlorpromazine, inhibits dopamine-stimulated phosphorylation.
• 6.5. Ouabain mimics the effect of cyproheptadine on the serotonin-stimulated phosphorylation found in the posterior gills.

     

The pH dependence of the affinity,kinetics and cooperativity of ligand binding to the root effect haemoglobin of the goldfish Carassius auratus

• 1.1. The binding of O₂ to goldfish haemoglobin showed a strong pH dependence P₅₀=5.5 mmHg; n = 2.4 at pH 8.0 and P₅₀ = 170 mmHg; n = 1.0 at pH 5.5 such that the protein is only 50% saturated in a solution of air equilibrated buffer at pH 5.5.
• 2.2. The binding of CO is cooperative at high pH (n = 2.8; L = 1000; K_R = 0.1 μM; K_T = 4 μM) and non-cooperative (n = 1) at pH 5.5.
• 3.3. The rate of O₂ dissociation is extremely fast and pH dependent; being 30 sec⁻¹ at pH 8.0 and 400 sec⁻¹ at pH 6.0 at 1°C. At 23°C the rate of this process is too fast to obtain accurate data using stopped-flow techniques.
• 4.4. Partial photolysis of the oxyhaemoglobin species leads to homogeneous recombination kinetics at pH 8.0 with an associated rate constant of 4.7 × 10⁷ M⁻¹ sec⁻¹. At pH < 7.5 the recombination process occurs in two steps. One rate is equal to that observed at pH 8.0. The slower process is favoured at low pH.
• 5.5. Photolysis of the CO haemoglobin complex indicates that, at high pH, combination of CO with deoxyhaemoglobin is cooperative, whilst recombination with Hb(CO)₃ is non-cooperative and occurs at a rate of 1.2 × 10⁶ M⁻¹ sec⁻¹.
• 6.6. At neutral pH recombination of CO with partially linganded haemoglobin occurs in a two-step process. The proportion contributed by each of these two steps in pH dependent.
• 7.7. The functioning of this Root effect haemoglobin is discussed in terms of the two state-model of cooperativity in which the αβ chain heterogeneity is minimal

     

Effects of 2,4-dinitrophenol on trichomonads and Entamoeba invadens

• 1.1. 2,4-Dinitrophenol (2,4-DNP) in substrate level concentrations (200 μM-1 mM) temporarily inhibits H₂ production by Tritrichomonas foetus and Trichomonas vaginalis as well as the accumulation of metronidazole, dependent on its reduction by the two trichomonad species and by Entamoeba invadens.
• 2.2. 2,4-DNP competes for the reducing equivalents which are necessary for H₂ production or for the reduction of metronidazole, thereby inhibiting these processes. 2,4-DNP is reduced to 2-amino, 4-nitrophenol.
• 3.3. 2,4-DNP in concentrations up to 800 μM has no effect on the uptake of O₂ by these organisms.
• 4.4. 2,4-DNP has some toxicity for T. foetus.

     

The dependence of oxygen consumption of the common whelk (Buccinum undatum) on hypoxia,salinity and air exposure

• 1.1. Oxygen consumption of low salinity (20‰) acclimated whelks decreases markedly upon acute exposure to hypoxia (P_WO₂ = 35 Torr), but almost regenerates its original level within 48 hr exposure to the hypoxic condition.
• 2.2. This ability to regain the original level of oxygen consumption is not seen in high salinity (35‰) acclimated whelks.
• 3.3. Oxygen consumption in air at 10°C is more than twice the rate shown by low salinity acclimated whelks in normoxic water (P_WO₂ = 150 Torr).
• 4.4. Q₁₀ for oxygen consumption in air is about 1.0 in the temperature range 10–20°C.

     

Oxygen uptake in larval bollworms (Heliothis zea) infected with the fungus Nomuraea rileyi

• 1.1. Healthy 6- to 12-day-old Heliothis zea (bollworm) larvae showed a mean oxygen uptake of 3.1 μl O₂/mg body wt per hr.
• 2.2. Similar larvae infected with the fungus Nomuraea rileyi had a mean uptake of 4.01 μl O₂/mg per hr.
• 3.3. The weights of the two groups of insects did not differ.
• 4.4. T-test showed a significant (P < 0.01) difference in oxygen uptake between healthy and infected larvae.

     

Cellular and intracellular localization of catalase and acid phosphatase in the midgut of Lumbricus terrestris L.: A cell fractionation study

• 1.1. Cellular and intracellular localization of catalase and acid phosphomonoesterase in the midgut of Lumbricus terrestris was studied by use of tissue fractionation.
• 2.2. At least 60–70% of the catalase resides in the chloragocyte cytosol and the remaining 30–40% resides in gut epithelium peroxisomes.
• 3.3. One of the main functions of the chloragocyte catalase is probably scavenging for H₂O₂ arising from the interaction between blood heme-protein and oxygen.
• 4.4. A simple method for the histochemical detection of cytosol catalase is proposed.
• 5.5. About 10% of the gut acid phosphatase resides in chloragocyte lysosomes. The chloragosomes contain no acid phosphatase.

     

An alkaline phosphatase from Thermus sp strain Rt41A

• 1.1. A thermostable orthophosphoric monoester phosphohydrolase (EC 3.1.3.1) from Thermus sp strain Rt41A has been purified 400-fold to give a specific activity of 25 U/mg at 60°C in IM diethanolamine (pH 11.1).
• 2.2. The enzyme has a M_r of 160,000 and is trimeric.
• 3.3. The half-life of the enzyme is 5 min at 85°C.
• 4.4. The enzyme has a wide specificity for a number of phosphate monoesters.
• 5.5. The H_m of the enzyme is pH dependent, so the pH optimum of the enzyme is affected by the substrate concentration.
• 6.6. The enzyme is inhibited 50% by 20 mM Ca²⁺ or Mg²⁺.
• 7.7. The K_i for phosphate, EDTA-di sodium salt and arsenate (in 1 M diethanolamine, pH 11.1) is approx 1.2, 1.6 and 4mM respectively.
• 8.8. Urea (200 mM) is not inhibitory.

     

Responses of mixed-function oxygenase and antioxidase enzyme system of Mytilus sp. to organic pollution

• 1.1. Mixed-function oxidase (MFO) system components (cytochrome P-450, “418-peak”, cytochrome b₅ and NADPH-cytochrome c (P-450) reductase) and inducible antioxidant enzymes (catalase, Superoxide dismutase (SOD), glutathione peroxidase (GPX) and DT-diaphorase) has been determined in digestive glands of mussels (Mylilus galloprovincialis) collected from three Mediterranean coastal locations, exhibiting an organic pollution gradient.
• 2.2. Cytochrome P-450, the “418-peak”, catalase and SOD showed a good correlation with whole body tissue PAHs and, to a lower extent, with PCBs.
• 3.3. Microsomal NADPH-dependent DT-diaphorase, but not the NADH-dependent microsomal enzyme or the cytosolic DT-diaphorases, was indicated to increase with pollution exposure.
• 4.4. The application of such measurements to environmental monitoring is discussed. Given the magnitude of differences observed, and the state of knowledge on enzyme function and mechanisms of toxicity, a multiparameter approach is considered to offer current and future potential for detecting the impact of organic pollution on bivalve molluscs.