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Understanding the ecophysiological and nutrient-use strategies of dominant species is important for clarifying plant growth and an ecological process in their community under unbalanced N and P inputs. This study investigated effects of N and P addition [main plot: 0, 25, 50, and 100 kg(N) ha-1 year-1; subplot: 0, 20, 40, and 80 kg(P) ha-1 year-1] on leaf N and P contents (LNCa and LPCa), photosynthetic capacity (PNmax) and photosynthetic N- and P-use efficiencies (PNUE and PPUE) in three species (Stipa bungeana, Bothriochloa ischaemum, and Lespedeza davurica) in a semiarid grassland in China. At the assessing time, N addition alone significantly increased LNCa and LNCa/LPCa ratio of Stipa bungeana (C3 grass) only, while PNmax increased significantly in all three species. Under N addition, P addition caused significantly lower LNCa, but higher PNUE and PNmax in Bothriochloa ischaemum (C4 grass) and Stipa bungeana. The LNCa, PNmax, and PNUE of Lespedeza davurica (C3 legume) increased significantly after P addition regardless of N application. The LNCa/LPCa for optimum PNUE changed with species. The PNmax and PNUE of Bothriochloa ischaemum and Stipa bungeana had a peak when LNCa/LPCa attained ~ 11 and ~ 20. Lespedeza davurica tended to retain greater PNmax and PNUE at lower LNCa/LPCa. Our results indicated that the C3 grass was more sensitive to N and P addition than the C4 grass and the C3 legume in terms of leaf N and P contents and PNmax. Such interspecific variations of nutrient use in response to N and/or P addition are favorable for maintaining the diversity and the stability of the grassland community. [ABSTRACT FROM AUTHOR]

We examine a simple model of the liquid state of an electrorheological fluid, with emphasis on the role of many-particle (local-field) effects. The induced dipole moments are treated as internal degrees of freedom. The distribution function for these dipole moments is calculated self-consistently within the mean-spherical approximation (MSA). The present MSA formalism is more rigorous and slightly more general than the ‘‘mean-field’’ treatment by Adriani and Gast [Phys. Fluids 31, 2757 (1988)]. We also use a more accurate MSA correlation function which leads to numerical results suggestive of a phase transition out of the liquid state at a critical value of the dimensionless dipole interaction strength. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To investigate the expression of kir6.2 subunit of the sarcKATP channel in exercise-induced myocardial injury and to elucidate the underlying mechanism of myocardial protection by sarcKATP channels. MATERIALS AND METHODS: Healthy male Sprague Dawley(SD) rats were divided into the Control (C) and the Exhaustive Exercise (EE) group. The one-time exhaustive exercise-induced myocardial injury model was established on a treadmill at a speed of 35 m/min. Alterations in myocardial ischemia and hypoxia were examined by hematoxylin-basic fuchsin-picric acid (HBFP) staining and the concentration of cardiac Troponin I (cTnl), a sensitive and specific marker for myocardial injury, was detected using immunochemiluminescence analysis. The mRNA expression level, localization, and protein expression of sarcKATP channel subunit kir6.2 were determined by quantitative reverse transcriptase- polymerase chain reaction (qRT-PCR), immunofluorescence, and Western blot analysis, respectively. RESULTS: When compared to Group C, rats in Group EE demonstrated significantly increased areas of myocardial ischemia and hypoxia. Moreover, increased serum levels of cTnI were detected. Increased kir6.2 expression was found on the surface of cardiomyocytes and kir6.2 protein expression was also significantly increased. CONCLUSIONS: Exercise-induced myocardial injury did not result in noticeable alterations in kir6.2 mRNA expression. However, kir6.2 protein expression was significantly increased and resulted in increased numbers of sarcKATP channel openings in the myocardium, thereby further inhibiting exercise-induced myocardial injury. [ABSTRACT FROM AUTHOR]

Bothriochloa ischaemum L. is an important species in many temperate regions, but information about the interactive effects of water stress and fertilization on its photosynthetic characteristics was inadequate. A pot experiment was conducted to investigate the effects of three water [80% (HW), 40% (MW), and 20% (LW) of field capacity (FC)] and four fertilization regimes [nitrogen (N), phosphorus (P), nitrogen with phosphorus (NP), and no fertilization] on leaf photosynthesis. Leaf gas exchange and photosynthetic light-response curves were measured at the flowering phase of B. ischaemum. Water stress decreased not only the leaf gas-exchange parameters, such as net photosynthetic rate ( PN), stomatal conductance ( gs), transpiration rate ( E), and water-use efficiency (WUE) of B. ischaemum, but also downregulated PN-photosynthetically active radiation (PAR) curve parameters, such as light-saturated net photosynthetic rate ( PNmax), apparent quantum efficiency (AQE), and light compensation point (LCP). Fertilization (N, P, and NP) enhanced the daily mean PN values and PNmax under the HW regime. Addition of N (either alone or with P) improved the photosynthetic capacity of B. ischaemum under the MW and LW regimes by increasing PN, PNmax, and AQE and reducing dark respiration rate and LCP, but the addition of P alone did not significantly improve the photosynthetic performance. Decline in PN under each fertilization regime occurred during the day and it was caused mainly by nonstomatal limitation. Our results indicated that water was the primary limiting factor for photosynthesis in B. ischaemum, and that appropriate levels of N fertilization improved its potential photosynthetic capacity under water-deficit conditions. [ABSTRACT FROM AUTHOR]

Perennial forage legumes, particularly lucerne ( Medicago sativa L.), play a significant role in crop/livestock mixed farming systems in the semiarid region of the Loess Plateau of China as stock feed and a source of nitrogen for subsequent crops. However, there is evidence that lucerne reduces soil water deep in the soil profile, thereby reducing subsequent crop productivity. From 2004 to 2010, this study evaluated the forage productivity and water use of two locally adapted perennial legume species, milk vetch ( Astragalus adsurgens Pall.) and bush clover ( Lespedeza davurica S.), compared with lucerne. The 7-year total and average annual forage yield of milk vetch were 56 and 8 t ha−1 and bush clover was 42 and 6 t ha−1, respectively, significantly lower than lucerne at 91 and 13 t ha−1. However, despite lower water-use efficiencies (16 and 12 kg ha−1 mm−1 for milk vetch and bush clover, respectively, compared to 22 kg ha−1 mm−1 for lucerne), the total 7-year water use in milk vetch and bush clover was 3500 mm and 3490 mm, respectively, which was 135-140 mm less than lucerne. After 7 years, lucerne had extracted water from the upper 5 m soil, whereas bush clover used water mainly from the upper 2 m of the soil profile and milk vetch still had some water available below 3 m. We conclude that while the locally adapted forage legumes were not as productive as lucerne as a source of fodder in mixed cropping/livestock system in this region, they use less water, which may be advantageous in drier regions. [ABSTRACT FROM AUTHOR]

Poly(ℇ-caprolactone) was characterized by size exclusion chromatography on-line with a right-angle laser-light scattering photometer and a four-capillary bridge design differential viscometer (SEC/RI/RALLS/DV) in tetrahydrofuran (THF) at 25°C. The dependence of intrinsic viscosity and radius of gyration of poly(ℇ-caprolactone) on molecular weight was established, and Flory's characteristic ratio C ∞ was calculated for this polymer from these data. The results show that THF is a good solvent for poly(ℇ-caprolactone). Poly(ℇ-caprolactone) exhibits a random-coil conformation in THF, and SEC with online RALLS and DV detectors offer an easy way to obtain information on chain flexibility. The C ∞ results are in good accord with previously reported values for this polymer. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effects of shackling and wing flapping on stress, postmortem metabolism, AMP-activated protein kinase (AMPK), and quality of broiler pectoralis major. Before slaughter, a total of 80 Arbor Acres broilers was randomly categorized into 2 replicate pens (40 broilers per pen) and each pen randomly divided into 2 groups (shackling, T; control, C). Corticosterone, creatine kinase, and lactate dehydrogenase were determined on blood plasma parameters. Pectoralis major were removed after evisceration and used for determination of energy metabolism, meat quality, and AMPK phosphorylation. In this study, shackling and wing flapping increased (P  < 0.05) plasma corticosterone level, creatine kinase activity, and lactate dehydrogenase activity. Shackling and wing flapping increased (P  < 0.05) AMPKα(Thr172) and acetyl-CoA carboxylase (ACC) phosphorylation, followed by rapid glycolysis and accumulation of lactic acid, and leading to a fast pH decline in the initial postmortem meat. Shackling and wing flapping have an adverse effect on final meat quality, which increased (P  < 0.05) muscle lightness, drip loss, and cooking loss. The results indicate that antemortem shackling and wing flapping increased stress and AMPKα(Thr172) phosphorylation, which may accelerate glycolysis and lead to a low water-holding capacity of broiler meat. [ABSTRACT FROM AUTHOR]