Effect of renoguanylin on hydrogen/bicarbonate ion transport in rat renal tubules

Renoguanylin (REN) is a recently described member of the guanylin family, which was first isolated from eels and is expressed in intestinal and specially kidney tissues. In the present work we evaluate the effects of REN on the mechanisms of hydrogen transport in rat renal tubules by the stationary microperfusion method. We evaluated the effect of 1 μM and 10 μM of renoguanylin (REN) on the reabsorption of bicarbonate in proximal and distal segments and found that there was a significant reduction in bicarbonate reabsorption. In proximal segments, REN promoted a significant effect at both 1 and 10 μM concentrations. Comparing control and REN concentration of 1 μM, JHCO₃⁻, nmol cm^− 2 s^− 1 − 1,76 ± 0,11_control × 1,29 ± 0,08_{REN 10 μM}; P < 0.05, was obtained. In distal segments the effect of both concentrations of REN was also effective, being significant e.g. at a concentration of 1 μM (JHCO₃⁻, nmol cm^− 2 s⁻ 1 − 0.80 ± 0.07_control × 0.60 ± 0.06_{REN 1 μM}; P < 0.05), although at a lower level than in the proximal tubule. Our results suggest that the action of REN on hydrogen transport involves the inhibition of Na⁺/H⁺exchanger and H⁺-ATPase in the luminal membrane of the perfused tubules by a PKG dependent pathway.     

The routine metabolic rate of mulloway (Argyrosomus japonicus: Sciaenidae) and yellowtail kingfish (Seriola lalandi: Carangidae) acclimated to six different temperatures

This study compared the mass-specific routine metabolic rate (RMR) of similar sized mulloway (Argyrosomus japonicus), a sedentary species, and yellowtail kingfish (Seriola lalandi), a highly active species, acclimated at one of several temperatures ranging from 10–35 °C. Respirometry was carried out in an open-top static system and RMR corrected for seawater–atmosphere O₂ exchange using mass-balance equations. For both species RMR increased linearly with increasing temperature (T). RMR for mulloway was 5.78T − 29.0 mg O₂ kg^− 0.8 h^− 1 and for yellowtail kingfish was 12.11T − 39.40 mg O₂ kg^− 0.8 h^− 1. The factorial difference in RMR between mulloway and yellowtail kingfish ranged from 2.8 to 2.2 depending on temperature. The energetic cost of routine activity can be described as a function of temperature for mulloway as 1.93T − 9.68 kJ kg^− 0.8 day^− 1 and for yellowtail kingfish as 4.04T − 13.14 kJ kg^− 0.8 day^− 1. Over the full range of temperatures tested Q₁₀ values were approximately 2 for both species while Q₁₀ responses at each temperature increment varied considerably with mulloway and yellowtail kingfish displaying thermosensitivities indicative of each species respective niche habitat. RMR for mulloway was least thermally dependent at 28.5 °C and for yellowtail kingfish at 22.8 °C. Activation energies (E_a) calculated from Arrhenius plots were not significantly different between mulloway (47.6 kJ mol^− 1) and yellowtail kingfish (44.1 kJ mol^− 1).     

Net release of dissolved organic matter by the scleractinian coral Acropora pulchra

The net production of dissolved organic matter (DOM) and dissolved combined and free amino acids (DCAA and DFAA, respectively) by the hermatypic coral Acropora pulchra was measured in the submerged condition, and the production rates were normalized to the coral surface area, tissue biomass, and net photosynthetic rates by zooxanthellae. When normalized to the unit surface area, the production rates of dissolved organic carbon and nitrogen (DOC and DON, respectively) were 37 and 4.4 nmol cm^− 2 h^− 1, respectively. Comparing with the photosynthetic rate by zooxanthellae, which was measured by ¹³C-tracer accumulation in the soft tissue of the coral colony, the release rate of DOC corresponded to 5.4% of the daily net photosynthetic production. The tissue biomass of the coral colony was 178 µmol C cm^− 2 and 23 µmol N cm^− 2, indicating that the release of DOC and DON accounted for 0.021% h^− 1 and 0.019% h^− 1 of the tissue C and N, respectively. The C:N ratios of the released DOM (average 8.4) were not significantly different from those of the soft tissue of the coral colonies (average 7.7). While DFAA did almost not accumulate in the incubated seawater, DCAA was considerably released by the coral colonies at the rate of 2.1 nmol cm^− 2 h^− 1 on average. Calculating C and N contents of the hydrolyzable DCAA, it was revealed that about 20% and 50%–60% of the released bulk DOC and DON, respectively, were composed of DCAA.     

V1 receptor in ENS mediates the excitatory effect of vasopressin on circular muscle strips of gastric body in vitro in rats

The purpose of this study was to localize vasopressin (VP) V_1a receptor in stomach and to characterize the role of VP in the regulation of gastric motility in rats. Double staining was used to locate the V_1a receptor in the gastric body of the rat. The contraction of the circular muscle strips of gastric body was monitored by a polygraph. V_1a receptor was expressed on the neurons of myenteric plexus of the gastric body. VP (10^− 10–10^− 6 M) caused a concentration-dependent contractile effect on the circular muscle strips of gastric body in vitro. V-1880 ([deamino-Pen¹, O-Me-Tyr², Arg⁸]-Vasopressin, 10^− 7 M), a V₁ receptor antagonist, inhibited the spontaneous contraction of the strips. Tetradotoxin (TTX, 10^− 6 M) and V-1880 (10^− 7 M) abolished the excitatory effect of VP. Atropine (10^− 6 M) partially inhibited VP-induced excitatory effect on the muscle strips but hexamethonium (10^− 4 M) did not influence it. These results suggest that V_1a receptor was expressed on the neurons of myenteric nerves. The cholinergic nerve was involved in the excitatory effect of VP on the contraction of gastric body.     

Production of superoxides and nitric oxide generation in haemocytes of mussel Mytilus galloprovincialis (Lmk.) after exposure to cadmium: A possible involvement of Na/H exchanger in the induction of cadmium toxic effects

The present study investigates cadmium (Cd) ability to enhance superoxides (O₂⁻) and nitric oxide (NO) production (as nitrites) in haemocytes of mussel Mytilus galloprovincialis as well as the possible involvement of Na⁺/H⁺ exchanger (NHE) in the induction of NADPH oxidase and NO synthase activity. PMA, a well-known PKC-mediated NADPH oxidase as well as NO synthase stimulator was also used, in order to verify Cd effects on both O₂⁻ and NO generation. According to the results of the present study, micromolar concentrations of Cd (0.05, 5, 10 and 50 μM) seemed to enhance O₂⁻ and NO generation in haemocytes of mussels. Moreover, O₂⁻ and NO generation in haemocytes exposed to Cd could be enhanced by its ability to induce reactive oxygen species (ROS) but respiratory burst activation as well. Inhibition of NO synthase with 10 μM l-NAME, significantly attenuated Cd ability to enhance O₂⁻ production and diminished NO generation, thus leading to the suggestion that Cd toxic effects, started at concentration of 50 μM, could enhance NADPH oxidase and NO synthase stimulation in haemocytes of mussels. NHE seems to play a regulatory role in the induction of either O₂⁻ or NO generation in haemocytes exposed to the metal, since its inhibition with the use of 10 μM EIPA significantly decrease both O₂⁻ and NO production. The involvement of NHE in the induction of O₂⁻ and NO generation, probably via PKC-mediated NADPH oxidase and NO synthase activation, is likely to be crucial to haemocytes exposed to heavy metals, such as Cd.     

Red HE7B degradation using desulfonation by Pseudomonas desmolyticum NCIM 2112

Red HE7B (RHE7B, 100 mg l⁻¹), a sulfonated azo dye, was decolorized at static condition by Pseudomonas desmolyticum NCIM 2112 in 72 h with 71% reduction in chemical oxygen demand (COD). Extracellular lignin peroxidase (LiP) has played a crucial role in breakdown of the dye by asymmetric cleavage and reductases in the initial 24 h incubation to break azo bonds of some dye molecules. Dye also induced the activity of aminopyrine N-demethylase, one of the enzymes of mixed function oxidase system. Decolorization and degradation were analyzed by using UV–vis and high-pressure liquid chromatography (HPLC). The Fourier transform infrared spectroscopy (FTIR) analysis revealed that P. desmolyticum preferred C–N and SO bonds to break down the RHE7B. GC–MS identification of 8-amino-naphthalene-1,3,6,7-tetraol and 2-hydroxyl-6-oxalyl-benzoic acid as final metabolites supports the degradation of RHE7B by desulfonation before and after ring cleavage. Aerobic degradation of amines and reduced phytotoxicity increased the applicability of this microorganism for dye removal.

Scientific relevance of the paper

This is the first report on degradation of Red HE7B by oxidative enzymes and on further degradation by desulfonation before and after ring cleavage.     

Biodeterioration of some herbal raw materials by storage fungi and aflatoxin and assessment of Cymbopogon flexuosus essential oil and its components as antifungal

Deterioration of raw materials of six medicinal plants viz. Terminalia arjuna, Acorus calamus, Rauvolfia serpentina, Holarrhena antidysenterica, Withania somnifera and Boerhaavia diffusa was examined. Some of the contaminated raw materials were found to be deteriorated by toxigenic strains of Aspergillus flavus and contain aflatoxin B₁ (41.0–95.4 μg kg⁻¹) which is above the permissible limit. Essential oil of Cymbopogon flexuosus and its components was found efficient in checking fungal growth and aflatoxin production. C. flexuosus essential oil absolutely inhibited the growth of A. flavus and aflatoxin B₁ production at 1.3 μl ml⁻¹ and 1.0 μl ml⁻¹ respectively. The individual oil components were more efficacious than the Cymbopogon oil as such which emphasizes masking of their efficacy when combined together. Eugenol exhibited potent antifungal and aflatoxin inhibitory activity at 0.3 μl ml⁻¹ and 0.1 μl ml⁻¹ respectively. Eugenol was found superior over some prevalent synthetic antimicrobials and exhibited broad fungitoxic spectrum against some biodeteriorating moulds. Prospects of exploitation of the oil and its components as acceptable plant based antimicrobials in qualitative as well as quantitative control of biodeterioration of herbal raw materials have been discussed.     

Kinetics of ammonium, nitrate and phosphorus uptake by Canna indica and Schoenoplectus validus

Canna indica L. is an upright perennial rhizomatous herb, and Schoenoplectus validus (Vahl) A. Löve and D. Löve is a tall, perennial, herbaceous sedge. The nutrient uptake kinetics of C. indica and S. validus were investigated using the modified depletion method after plants were grown for 4 weeks in simulated secondary-treated wastewater. The maximum uptake rate (I_max) and Michaelis–Menten constant (K_m) were estimated by iterative curve fitting. The I_max for NH₄N (623 μmol g⁻¹ dry root weight h⁻¹) was significantly higher than that for NO₃N (338 μmol g⁻¹ dry root weight h⁻¹) in S. validus. In contrast, no difference was observed in C. indica. The I_max values for NO₃N and NH₄N were higher in S. validus than in C. indica. A significantly lower K_m was detected for NO₃N uptake in C. indica (385 μmol L⁻¹) compared to that in S. validus (1908 μmol L⁻¹). The I_max for PO₄P did not differ between the plant species. The K_m for PO₄P was significantly higher in C. indica (157 μmol L⁻¹) than in S. validus (60 μmol L⁻¹). In conclusion, we found that S. validus preferred NH₄N over NO₃N, had greater capacity for N uptake and higher affinity for PO₄P, but C. indica had greater affinity for NO₃N. Nutrient uptake capacity is likely related to habitat preference, and is influenced by the structure of roots and rhizomes.     

ICChI, a glycosylated chitinase from the latex of Ipomoea carnea

A multi-functional enzyme ICChI with chitinase/lysozyme/exochitinase activity from the latex of Ipomoea carnea subsp. fistulosa was purified to homogeneity using ammonium sulphate precipitation, hydrophobic interaction and size exclusion chromatography. The enzyme is glycosylated (14–15%), has a molecular mass of 34.94 kDa (MALDI–TOF) and an isoelectric point of pH 5.3. The enzyme is stable in pH range 5.0–9.0, 80 °C and the optimal activity is observed at pH 6.0 and 60 °C. Using p-nitrophenyl-N-acetyl-β-d-glucosaminide, the kinetic parameters K_m, V_max, K_cat and specificity constant of the enzyme were calculated as 0.5 mM, 2.5 × 10⁻⁸ mol min⁻¹ μg enzyme⁻¹, 29.0 s⁻¹ and 58.0 mM⁻¹ s⁻¹ respectively. The extinction coefficient was estimated as 20.56 M⁻¹ cm⁻¹. The protein contains eight tryptophan, 20 tyrosine and six cysteine residues forming three disulfide bridges. The polyclonal antibodies raised and immunodiffusion suggests that the antigenic determinants of ICChI are unique. The first fifteen N-terminal residues G–E–I–A–I–Y–W–G–Q–N–G–G–E–G–S exhibited considerable similarity to other known chitinases. Owing to these unique properties the reported enzyme would find applications in agricultural, pharmaceutical, biomedical and biotechnological fields.     

In vivo real-time measurement of superoxide anion radical with a novel electrochemical sensor

The dynamics of superoxide anion (O₂⁻) in vivo remain to be clarified because no appropriate method exists to directly and continuously monitor and evaluate O₂⁻ in vivo. Here, we establish an in vivo method using a novel electrochemical O₂⁻ sensor. O₂⁻ generated is measured as a current and evaluated as a quantified partial value of electricity (Q_part), which is calculated by integration of the difference between the baseline and the actual reacted current. The accuracy and efficacy of this method were confirmed by dose-dependent O₂⁻ generation in xanthine–xanthine oxidase in vitro in phosphate-buffered saline and human blood. It was then applied to endotoxemic rats in vivo. O₂⁻ current began to increase 1 h after lipopolysaccharide, and Q_part increased significantly for 6 h in endotoxemic rats, in comparison to sham-treated rats. These values were attenuated by superoxide dismutase. The generation and attenuation of O₂⁻ were indirectly confirmed by plasma lipid peroxidation with malondialdehyde, endothelial injury with soluble intercellular adhesion molecule-1, and microcirculatory dysfunction. This is a novel method for measuring O₂⁻ in vivo and could be used to monitor and treat the pathophysiology caused by excessive O₂⁻ generation in animals and humans.     

L-Amino acid oxidase from Naja naja oxiana venom

A new l-amino acid oxidase (LAAO) was isolated from the Central Asian cobra Naja naja oxiana venom by size exclusion, ion exchange and hydrophobic chromatography. The N-terminal sequence and the internal peptide sequences share high similarity with other snake venom l-amino acid oxidases, especially with those isolated from elapid venoms. The enzyme is stable at low temperatures (− 20 °C, − 70 °C) and loses its activity by heating at 70 °C. Specific substrates for the isolated protein are l-phenylalanine, l-tryptophan, l-methionine and l-leucine. The enzyme has antibacterial activity inhibiting the growth of Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria. N. naja oxiana LAAO dose-dependently inhibited ADP- or collagen-induced platelet aggregation with IC₅₀ of 0.094 μM and 0.036 μM, respectively. The antibacterial and anti-aggregating activity was abolished by catalase.     

Leaf chlorophyll fluorescence, reflectance, and physiological response to freshwater and saltwater flooding in the evergreen shrub, Myrica cerifera

Photosynthesis, water relations, chlorophyll fluorescence, and leaf reflectance were used to evaluate stress due to freshwater and saltwater flooding in the evergreen coastal shrub, Myrica cerifera, under controlled conditions. M. cerifera forms large monospecific thickets that facilitate scaling up from leaf-level measurements to the landscape. Based on physiological responses, stress began by day 3 in flooded plants treated with 5, 10, and 15 g L⁻¹ salinity, as seen by significant decreases in stomatal conductance and net photosynthesis relative to control plants. Decreases in physiological measurements occurred by day 9 in freshwater flooded plants. Visible signs of stress occurred by day 5 for plants treated with 15 g L⁻¹, day 8 for flooded plants exposed to 10 g L⁻¹, and day 10 for those treated with 5 g L⁻¹ salinity. Significant differences in light-adapted fluorescence yield () were observed by day 3 in plants flooded with 5, 10, and 15 g L⁻¹ salinity and day 6 in freshwater flooded plants. Non-photochemical quenching (Φ_NPQ) increased with decreasing . In comparison, statistical differences in dark-adapted fluorescence yield (F_v/F_m) were observed by day 12 in plants flooded with 5, 10, and 15 g L⁻¹ salinity, well after visible signs of stress were apparent. Fluorescence parameters were successful at detecting and distinguishing both freshwater and saltwater flooding stress. A positive, linear correlation (r² = 0.80) was observed between and the physiological reflectance index (PRI). Xanthophyll-cycle dependent energy dissipation appears to be the underlying mechanism in protecting photosystem II from excess energy in saltwater flooded plants. was useful in detecting stress-induced changes in the photosystem before any visible signs of damage were evident at the leaf-level. This parameter may be linked to hyperspectral reflectance data for rapid detection of stress at the canopy-level.     

Catalase activity and rhythmic patterns in mouse brain, kidney and liver

To protect tissues from damaging effects of reactive oxygen species (ROS), organisms possess enzymatic and non-enzymatic antioxidant systems. Cytosolic-enzyme catalase (CAT) is a component of the antioxidant defence system that reduces hydrogen peroxide (H₂O₂) to water (H₂O). The aim of this study was to assess the variation of antioxidant enzyme CAT activity in brain, kidney and liver of adult male mice according to tissue-specific and temporal patterns within a 24-h period (12:12 L/D). The CAT activity was assayed at 4-h intervals. The Cosinor test programme was used to detect and confirm the best corresponding rhythm. In liver, the circadian rhythm of CAT was associated with ultradian components. The prominent circadian rhythm (with a period τ = 24 h) showed a peak located at the middle of the dark phase, more precisely  17 HALO (Hours After Light Onset). In kidney, only a circadian rhythm of CAT was validated with a peak time located at  17 HALO. However, in brain, the time pattern of CAT activity showed two peak times at  1 and  17 HALO, illustrating the existence of an ultradian rhythm (with a period τ = 12 h). The results showed significant organ differences with the highest activity in liver, compared with kidney (− 89%) and brain (− 98%). This might be related to several factors such as their respective physiological function, the risk of exposure to oxidative damage and the balance between synthesis and degradation of proteins during “normal metabolism”. Moreover, CAT activity revealed differences in time-related changes across a 24-h period that were more obvious in peak levels between the three tissues.     

Peculiarities of the antioxidant and radioprotective effects of hydrated C60 fullerene nanostuctures in vitro and in vivo

Aqueous solutions of highly stable supramolecular donor–acceptor complexes of chemically nonmodified pristine C₆₀ fullerene molecules with H₂O molecules (hydrated C₆₀ fullerene–C₆₀HyFn) and their labile nano-sized clusters were examined for their antioxidant effects on removal of hydroxyl radicals (OH) and protecting DNA against oxidative damage induced by ionizing radiation in vitro. The suppressing influence of C₆₀HyFn on the formation of OH-radicals in water exposed to X-rays at doses of 1–7 Gy was assessed by determination of oxidation levels of coumarin-3-carboxylic acid. C₆₀HyFn demonstrates apparent antiradical activity in vitro in the range of concentrations of 10⁻¹¹–10⁻⁶ M. Paradoxically, the OH-removing efficacy of C₆₀HyFn was in reverse correlation with fullerene concentration. It was hypothesized that the antiradical action of C₆₀HyFn in water medium generally is due to a “nonstoichiometric” mechanism, supposedly to a hydrated free radical recombination (self-neutralization), which is catalyzed by specific water structures ordered by C₆₀HyFn. With the use of 8-oxoguanine as a marker of oxidative damage to DNA, it has been demonstrated that C₆₀HyFn in concentrations of 10⁻⁷–10⁻⁶ M protects nucleic acids against radical-induced damage. The second part of the present study was aimed to evaluate the overall radioprotective efficacy of C₆₀HyFn in doses of 0.1 or 1 mg/kg b.w. injected intraperitoneally to mice either 1 h before or 15 min after lethal dose exposure of the X-ray (7 Gy) irradiation. Survival rate of the mice was observed at 30 day intervals after irradiation, while the weight gains of experimental animals were monitored as well. The most significant protective effect was demonstrated when 1 mg/kg dosage of C₆₀HyFn was administered before irradiation. The outcome of the substance testing is 15% survival rate of irradiated animals at 30 days of observation, and prevention of noticeable weight loss characteristic for radiation impact, versus unprotected control animals. In conclusion, results of the study obviate that the apparent protective action of C₆₀HyFn in vivo is determined by its considerable ability to decrease X-ray-generated reactive oxygen species. Based on the results and that neat C₆₀ is nontoxic, actually in the hydrated form, without side effects and with sufficient radioprotective effects in low doses, C₆₀HyFn may be considered as a novel antioxidant agent, which substantially diminishes the harmful effects of ionizing radiation.     

Plasma nitrite response and arterial reactivity differentiate vascular health and performance

NO is crucial for endothelial function and vascular health. Plasma nitrite (NO₂⁻) is the main oxidation product of NO and has been shown to reflect changes in eNOS activity. We hypothesized that plasma NO₂⁻ response to physical exercise stress along with physiological endothelial function would be reduced with increasing severity of vascular disease. Subject groups were: (a) risk factors but no vascular disease (RF); (b) Type 2 diabetes with no vascular disease (DM); (c) diagnosed peripheral arterial disease (PAD); and (d) DM + PAD. Venous blood was drawn at rest and 10 min following maximal exercise. Plasma samples were analyzed by reductive chemiluminescence. Brachial diameters were imaged prior to, during and following 5 min of forearm occlusion (BAFMD). There were no differences in resting plasma NO₂⁻ or BA diameters between groups. The PAD groups had lower age adjusted BAFMD responses (p  0.05). Within group analysis revealed an increase in NO₂⁻ in the RF group (+39.3%), no change in the DM (−15.51%), and a decrease in the PAD (−44.20%) and PAD + DM (−39.95%). This was maintained after adjusting for age and VO_2peak (p  0.05). ΔNO₂⁻ and BAFMD were the strongest independent predictors of VO_2peak in multivariate linear regression. These findings suggest ΔNO₂⁻ discriminates severity of cardiovascular disease risk, is related to endothelial function and predicts exercise capacity.     

Influence of diets supplemented with vitamins C and E on pirarucu (Arapaima gigas) blood parameters

This study evaluated the influence of diets supplemented with 500, 800, 1200 mg kg^− 1 of vitamin C (ascorbic acid or AA) and vitamin E (α-tocopherol or α-T) on the physiological responses of pirarucu fed for 2 months. Weight and mortality were not affected by dietary vitamin type or their concentrations. Significant increase (p < 0.05) on the red blood cells count was obtained on treatments with 800 and 1200 mg AA kg^− 1 and on the hemoglobin concentration on treatment with 500 mg α-T kg^− 1 relatively to control. Mean corpuscular volume presented a significant decrease (p < 0.05) on treatment with 800 and 1200 mg AA kg⁻¹ when compared to control. Mean corpuscular hemoglobin concentration was significantly high (p < 0.05) on treatment with 500 mg α-T kg^− 1. Only in vitamin C treatments, we noticed a significant increase (p < 0.05) in the number of leucocytes relative to control. All fish in the vitamin-supplemented treatments, except 500 mg AA kg^− 1, had high total protein values compared to control. Fish treated with 800 or 1200 mg α-T kg^− 1 also showed increases in plasma glucose concentrations. Our results suggest that 800 and 1200 mg AA kg^− 1 are probably the most suitable concentrations for pirarucu diets, although high vitamin E diets are not necessary for quantitative leucocyte increases for this species.     

Ventilatory responses to exercise and carbon dioxide in elderly and younger humans

The present investigation examined the relationship between CO₂ sensitivity [at rest (S _R) and during exercise (S _E)] and the ventilatory response to exercise in ten elderly (61–79 years) and ten younger (17–26 years) subjects. The gradient of the relationship between minute ventilation and CO₂ production ( _E/ CO₂) of the elderly subjects was greater than that of the younger subjects [mean (SEM); 32.8 (1.6) vs 27.3 (0.4); P<0.01]. At rest, S _R was lower for the elderly than for the younger group [10.77 (1.72) vs 16.95 (2.13) 1 · min^–1 · kPa^–1; 1.44 (0.23) vs 2.26 (0.28) 1 · min^–1 · mmHg^–1; P<0.05], but S _E was not significantly different between the two groups [17.85 (2.49) vs 19.17 (1.62) l · min^–1 · kPa^–1; 2.38 (0.33) vs 2.56 (0.21) 1 · min^–1 · mmHg^–1]. There were significant correlations between both S _R and S _E, and _E/ CO₂ (P<0.05; P<0.001) for the younger group, bot none for the elderly. The absence of a correlation for the elderly supports the suggestion that _E/ CO₂ is not an appropriate index of the ventilatory response to exercise for elderly humans.     

Western equatorial Pacific planktic foraminiferal fluxes and assemblages during a La Niña year (1999)

A correlation between foraminiferal community dynamics and environmental conditions may provide a basis for establishing paleoclimatic proxies. We studied planktic foraminiferal shell fluxes and assemblages in samples collected in three time-series sediment trap deployments in the western equatorial Pacific under La Niña conditions from January to November 1999. Eleven species contributed about 90% of the total flux in all traps. Two sites (MT1, MT3) in the Western Pacific Warm Pool region (WPWP) were characterized by common occurrences of the species Globigerinoides ruber, Globigerinoides sacculifer, Globigerinoides tenellus, and Neogloboquadrina dutertrei. Site MT5 farther to the east in the equatorial upwelling region had common occurrences of Globigerina bulloides, Globigerinita glutinata, and Pulleniatina obliquiloculata. Very high abundances of G. bulloides and G. glutinata at MT5 indicate that equatorial upwelling (EU) occurred during the 1999 La Niña. The two western sites have similar assemblage compositions, but MT1 ( 135°E) has the highest fluxes (up to  3800 tests m^− 2 day^− 1), whereas MT3 ( 145° E) has fluxes below  2200 tests m^− 2 day^− 1. Relatively high fluxes (up to  3000 tests m^− 2 day^− 1) occur at site MT5 ( 176° E), where upwelling occurred.The differences in faunal composition in the WPWP and EU might be attributable to differences in the way in which nutrients are supplied to the phytoplankton: large amounts of suspended material are supplied to the WPWP by advection of waters passing through the coastal region of an archipelago, whereas upwelling of nutrient-rich waters enhances primary production in the EU. At the westernmost site in the WPWP, a peak in the G. bulloides flux coincided with southward flow of the New Guinea Coastal Current (NGCC) in late February, but the highest G. ruber flux coincided with northward flow of this current in late May. Thus, the differences in species dominance at this location may be caused by monsoon-driven variability in the flow direction of the NGGC.     

Graphitized macroporous carbon microarray with hierarchical mesopores as host for the fabrication of electrochemical biosensor

A novel graphitized ordered macroporous carbon (GMC, pore size 380 nm) with hierarchical mesopores (2–30 nm) and high graphitization degree was prepared by nickel-catalyzed graphitization of polystyrene arrays. The obtained GMC possessed high specific surface area, large pore volume, and good electrical conductivity, which was explored for the enzyme entrapment and biosensor fabrication by a facile method. With advantages of novel nanostructure and good electrical conductivity, direct electrochemistry of hemoglobin (a model protein) was observed on the GMC-based biocomposite with a formal potential of −0.36 V (vs. Ag/AgCl) and an apparent heterogeneous electron transfer rate constant (k_s) of 1.2 s⁻¹ in pH 7.0 buffer. Comparative studies revealed that GMC offered significant advantages over carbon nanotubes (CNTs) in facilitating direct electron transfer of entrapped Hb. The fabricated biosensor exhibited good sensitivity (101.6 mA cm⁻² M⁻¹) and reproducibility, wide linear range (1–267 μM), low detection limit (0.1 μM), and good long-term stability for H₂O₂ detection. GMC proved to be a promising matrix for enzyme entrapment and biosensor fabrication, and may find wide potential applications in biomedical detection and environmental analyses.