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1.
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 ± 0,11control × 1,29 ± 0,08REN 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 ± 0.07control × 0.60 ± 0.06REN 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. 相似文献
2.
Igor Pirozzi Mark A. Booth 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2009,152(4):586-592
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 (Ea) calculated from Arrhenius plots were not significantly different between mulloway (47.6 kJ mol− 1) and yellowtail kingfish (44.1 kJ mol− 1). 相似文献
3.
Yasuaki Tanaka Toshihiro Miyajima Yu Umezawa Takeshi Hayashibara Hiroshi Ogawa Isao Koike 《Journal of experimental marine biology and ecology》2009,377(2):101-106
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. 相似文献
4.
The purpose of this study was to localize vasopressin (VP) V1a 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 V1a receptor in the gastric body of the rat. The contraction of the circular muscle strips of gastric body was monitored by a polygraph. V1a 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 V1a 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. 相似文献
5.
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. 相似文献
6.
Satish Kalme Gajanan Ghodake Sanjay Govindwar 《International biodeterioration & biodegradation》2007,60(4):327-333
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. 相似文献7.
Ashok Kumar Ravindra Shukla Priyanka Singh Nawal Kishore Dubey 《International biodeterioration & biodegradation》2009,63(6):712-716
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. 相似文献
8.
Kinetics of ammonium, nitrate and phosphorus uptake by Canna indica and Schoenoplectus validus 总被引:1,自引:0,他引:1
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 (Imax) and Michaelis–Menten constant (Km) were estimated by iterative curve fitting. The Imax 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 Imax values for NO3N and NH4N were higher in S. validus than in C. indica. A significantly lower Km was detected for NO3N uptake in C. indica (385 μmol L−1) compared to that in S. validus (1908 μmol L−1). The Imax for PO4P did not differ between the plant species. The Km 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. 相似文献
9.
Ashok Kumar Patel Vijay Kumar Singh Ravi Prakash Yadav A.J.G. Moir Medicherla V. Jagannadham 《Phytochemistry》2009,70(10):1210-1216
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 Km, Vmax, Kcat 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. 相似文献
10.
Motoki Fujita Ryosuke Tsuruta Shunji Kasaoka Kenji Fujimoto Ryo Tanaka Yasutaka Oda Masahiro Nanba Masatsugu Igarashi Makoto Yuasa Toshikazu Yoshikawa Tsuyoshi Maekawa 《Free radical biology & medicine》2009,47(7):1039-1048
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 (Qpart), 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 Qpart 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. 相似文献
11.
Samel M Tõnismägi K Rönnholm G Vija H Siigur J Kalkkinen N Siigur E 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2008,149(4):572-580
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. 相似文献
12.
Julie C. Naumann Donald R. Young John E. Anderson 《Environmental and Experimental Botany》2008,63(1-3):402-409
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 (ΦNPQ) increased with decreasing . In comparison, statistical differences in dark-adapted fluorescence yield (Fv/Fm) 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. 相似文献
13.
Sani M Sebaï H Gadacha W Boughattas NA Reinberg A Mossadok BA 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2006,145(3-4):331-337
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. 相似文献
14.
Grigory V. Andrievsky Vadim I. Bruskov Artem A. Tykhomyrov Sergey V. Gudkov 《Free radical biology & medicine》2009,47(6):786-793
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. 相似文献
15.
Jason D. Allen Elizabeth M. Miller Earl Schwark Jennifer L. Robbins Brian D. Duscha Brian H. Annex 《Nitric oxide》2009,20(4):231-237
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 VO2peak (p 0.05). ΔNO2− and BAFMD were the strongest independent predictors of VO2peak in multivariate linear regression. These findings suggest ΔNO2− discriminates severity of cardiovascular disease risk, is related to endothelial function and predicts exercise capacity. 相似文献
16.
Jaqueline Inês Alves de Andrade Eduardo Akifumi Ono Glauber Cruz de Menezes Elenice Martins Brasil Rodrigo Roubach Elisabeth Criscuolo Urbinati Marcos Tavares-Dias Jaydione Luiz Marcon Elizabeth Gusmo Affonso 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2007,146(4):576
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. 相似文献
17.
A. K. McConnell E. S. G. Semple C. T. M. Davies 《European journal of applied physiology and occupational physiology》1993,66(4):332-337
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. 相似文献
18.
Western equatorial Pacific planktic foraminiferal fluxes and assemblages during a La Niña year (1999) 总被引:1,自引:0,他引:1
Makoto Yamasaki Akira Sasaki Motoyoshi Oda Hanako Domitsu 《Marine Micropaleontology》2008,66(3-4):304-319
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. 相似文献
19.
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 (ks) 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. 相似文献