Effect of dietary β-glucan on growth performance,fecal microbial shedding and immunological responses after lipopolysaccharide challenge in weaned pigs

Two experiments (Exp.) were conducted to evaluate the effects of β-glucan inclusion in the diet on growth performance and immune function after lipopolysaccharide (LPS) challenge. In Exp. 1, a total of 40 weaned pigs (progeny of Landrace×Yorkshire sows by Duroc) with an initial body weight (BW) of 7.89 ± 0.84 kg (21 ± 2 d) of age) were used in a 28-day (d) experiment to determine the effects of dietary β-glucan on growth performance. Pigs were allotted randomly to two treatments consisting of addition of 0 or 0.1 g β-glucan/kg diet with four replicate pens per treatment and five pigs per pen. Growth performance was not affected by β-glucan supplementation throughout the experiment. However, dietary β-glucan reduced (P<0.05) the number of fecal Escherichia coli. In Exp. 2, a total of 20 weaned barrows (6.22 ± 0.25 kg of BW and 21 ± 2 d of age) individually raised in metabolic cages were used to evaluate immunological responses following LPS challenge. Pigs were fed 0 or 0.1 g β-glucan/kg diet for 42 d. At the end of the trial, half of the pigs (n = 5) from each treatment were injected intraperitoneal with E. coli LPS at a concentration of 100 μg/kg BW and the other half were injected with sterile saline solution. Treatments were arranged as a 2×2 factorial, with the main effect of LPS challenge (saline vs. LPS) and β-glucan supplementation (0 g/kg vs. 0.1 g/kg). After LPS injection, blood was taken at 0, 2, 4, 6, 8 and 12 hours (h) for the blood cell counts and blood inflammatory response. Dietary β-glucan increased (P<0.05) leukocytes counts at 4, 6 and 8 h, and blood lymphocyte concentrations at 2, 4 and 6 h and LPS challenge increased (P<0.05) counts of leukocytes at 2, 4, 6 and 8 h and blood lymphocyte at 2 and 4 h post-challenge. The rectal temperature was increased (P<0.05) at 2, 4, 6 and 8 h after LPS challenge. Dietary β-glucan reduced (P<0.05) and LPS challenge increased (P<0.05) blood plasma tumor necrosis factor-α (TNF-α) concentration at 2 and 4 h post-challenge. Dietary β-glucan increased (P<0.05) the concentration of the cluster of differentiation antigens 4 cells (CD4⁺) at 2, 4 and 6 h, and of 8 (CD8⁺) at 4 and 6 h post-challenge, respectively. The LPS challenge increased (P<0.05) CD4⁺ and CD8⁺ cell concentrations at 2, 4 and 6 h post-challenge. The CD4⁺:CD8⁺ ratio was reduced (P<0.05) by LPS challenge but was increased (P<0.05) by dietary β-glucan at 2, 4, 6 and 8 h post-challenge. In conclusion, dietary β-glucan decreased E. coli numbers but did not affect growth performance in weaned pigs and may offer benefits on immune function in weaned pigs challenged with LPS.     

Feruloyl esterase production by Aspergillus terreus CECT 2808 and subsequent application to enzymatic hydrolysis

Ferulic acid esterases (FAE) were produced by Aspergillus terreus CECT 2808 from vine trimming shoots (VTS) and corn cob. Later, the fungal extracts thus obtained were used to enzymatically release ferulic acid (FA) from both substrates. Our findings showed a higher FAE activity in the enzymatic extracts produced on corn cob (0.070 ± 0.004 U/mL). Nevertheless, the enzymatic extracts produced on VTS demonstrated a better performance for FA release from both corn cob (2.05 ± 0.01 mg/g) and VTS (0.19 ± 0.003 mg/g). This result was probably because of the higher xylanase/FAE ratio determined in VTS extract. Therefore, an additional assay was carried out by supplementing corn cob extract with a commercial xylanase to test the influence of FAE/xylanase ratio in FA release. The results revealed the relevance of the FAE/xylanase ratio for an optimal FA release.     

Involvement of store-operated Ca2 + entry in activation of AMP-activated protein kinase and stimulation of glucose uptake by M3 muscarinic acetylcholine receptors in human neuroblastoma cells

G_q/11-coupled muscarinic acetylcholine receptors (mAChRs) belonging to M₁, M₃ and M₅ subtypes have been shown to activate the metabolic sensor AMP-activated protein kinase (AMPK) through Ca^2 +/calmodulin-dependent protein kinase kinase-β (CaMKKβ)-mediated phosphorylation at Thr172. However, the source of Ca^2 + required for this response has not been yet elucidated. Here, we investigated the involvement of store-operated Ca^2 + entry (SOCE) in AMPK activation by pharmacologically defined M₃ mAChRs in human SH-SY5Y neuroblastoma cells. In Ca^2 +-free medium the cholinergic agonist carbachol (CCh) caused a transient increase of phospho-Thr172 AMPK that rapidly ceased within 2 min. Conversely, in the presence of extracellular Ca^2 + CCh-induced AMPK phosphorylation lasted for at least 180 min. The SOCE modulator 2-aminoethoxydiphephenyl borate (2-APB), at a concentration (50 μM) that suppressed CCh-induced intracellular Ca^2 + ([Ca^2 +]_i) plateau, inhibited CCh-induced AMPK phosphorylation. CCh triggered the activation of the endoplasmic reticulum Ca^2 + sensor stromal interaction molecule (STIM) 1, as indicated by redistribution of STIM1 immunofluorescence into puncta, and promoted the association of STIM1 with the SOCE channel component Orai1. Cell depletion of STIM1 by siRNA treatment reduced both CCh-induced [Ca^2 +]_i plateau and AMPK activation. M₃ mAChRs increased glucose uptake and this response required extracellular Ca^2 + and was inhibited by 2-APB, STIM1 knockdown, CaMKKβ and AMPK inhibitors, and adenovirus infection with dominant negative AMPK. Thus, the study provides evidence that SOCE is required for sustained activation of AMPK and stimulation of downstream glucose uptake by M₃ mAChRs and suggests that SOCE is a critical process connecting M₃ mAChRs to the control of neuronal energy metabolism.     

Effects of corn distillers dried grains with solubles and xylanase on growth performance and digestibility of diet components in broilers

The objective of this study was to investigate the effect of corn distillers dried grains with solubles (cDDGS) and xylanase in corn-based diets on growth performance and digestibility of diet components in broiler chickens. The experiment was a 3×4 factorial design with diets containing 3 levels of cDDGS (0, 100 and 200 g/kg) and 4 levels of xylanase (0, 1200, 2400 and 3600 U/kg). The diets were fed to 720 Cobb 500 chicks for 42 days. Excreta was collected at 18–21 days to measure coefficients of total tract apparent digestibility (CTTAD) and ileal digesta was collected at 42 days to measure coefficients of ileal apparent digestibility (CIAD). Dietary cDDGS caused poor (P<0.05) feed conversion ratio (FCR) of broilers from 1 to 21 and 22 to 42 days, but increased (P<0.05) feed intake (FI) at 1–21 days. Inclusion of xylanase increased (P<0.05) FI by 4–5% at 1–21 days, and did not affect (P≥0.05) FCR in either period. In the two growing periods, cDDGS decreased (P<0.05) the CTTAD of dry matter (DM), and the CIAD of DM and hemicelluloses, whereas xylanase increased (P<0.05) the digestibility of DM and hemicellulose by 5% and 20%, respectively. There were significant interactions (P<0.05) between cDDGS and xylanase for BWG and energy digestibility. In comparison with the 100 g/kg cDDGS diet, the inclusion of 200 g/kg cDDGS led to poorer (P<0.05) FCR at 22–42 days, and lower (P<0.05) CTTAD of DM at 18–21 days. There were no differences (P≥0.05) in most growth parameters between the doses of xylanase at 1200, 2400 and 3600 U/kg. Xylanase at 2400 U/kg increased (P<0.05) CTTAD of DM compared with the lower dose, but 3600 U/kg xylanase showed no further improvement (P≥0.05) on digestibility measurements. The results suggest that supplementing xylanase to diets containing cDDGS can improve growth performance and digestibility of diet components in broilers.     

Proton production from nitrogen transformation drives stream export of base cations in acid-sensitive forested watersheds

The biogeochemical cycles of nitrogen (N) and base cations (BCs), (i.e., K⁺, Na⁺, Ca²⁺, and Mg²⁺), play critical roles in plant nutrition and ecosystem function. Empirical correlations between large experimental N fertilizer additions to forest ecosystems and increased BCs loss in stream water are well demonstrated, but the mechanisms driving this coupling remain poorly understood. We hypothesized that protons generated through N transformation (PPR_N)—quantified as the balance of NH₄⁺ (H⁺ source) and NO₃⁻ (H⁺ sink) in precipitation versus the stream output will impact BCs loss in acid-sensitive ecosystems. To test this hypothesis, we monitored precipitation input and stream export of inorganic N and BCs for three years in an acid-sensitive forested watershed in a granite area of subtropical China. We found the precipitation input of inorganic N (17.71 kg N ha⁻¹ year⁻¹ with 54% as NH₄⁺–N) was considerably higher than stream exported inorganic N (5.99 kg N ha⁻¹ year⁻¹ with 83% as NO₃⁻–N), making the watershed a net N sink. The stream export of BCs (151, 1518, 851, and 252 mol ha⁻¹ year⁻¹ for K⁺, Na⁺, Ca²⁺, and Mg²⁺, respectively) was positively correlated (r = 0.80, 0.90, 0.84, and 0.84 for K⁺, Na⁺, Ca²⁺, and Mg²⁺ on a monthly scale, respectively, P < 0.001, n = 36) with PPR_N (389 mol ha⁻¹ year⁻¹) over the three years, suggesting that PPR_N drives loss of BCs in the acid-sensitive ecosystem. A global meta-analysis of 15 watershed studies from non-calcareous ecosystems further supports this hypothesis by showing a similarly strong correlation between ∑BCs output and PPR_N (r = 0.89, P < 0.001, n = 15), in spite of the pronounced differences in environmental settings. Collectively, our results suggest that N transformations rather than anions (NO₃⁻ and/or SO₄²⁻) leaching specifically, are an important mediator of BCs loss in acid-senstive ecosystems. Our study provides the first definitive evidence that the chronic N deposition and subsequent transformation within the watershed drive stream export of BCs through proton production in acid-sensitive ecosystems, irrespective of their current relatively high N retention. Our findings suggest the N-transformation-based proton production can be used as an indicator of watershed outflow quality in the acid-sensitive ecosystems.     

Rumen microbial responses in fermentation characteristics and production of CLA and methane to linoleic acid in associated with malate or fumarate

An in vitro incubation in batch was conducted to investigate the effect of propionate precursor (malate or fumarate) on fermentation characteristics, and production of CLA and methane by rumen microbes when incubated with linoleic acid (C_18:2). Sixty milligrams of C_18:2 alone (LA), 60 mg C_18:2 with 24 mM malic acid (M-LA), or 60 mg C_18:2 with 24 mM fumaric acid (F-LA) was added to 150 ml culture solution consisting of 75 ml strained rumen fluid and 75 ml McDougall's artificial saliva. Culture solution for incubation was also made without malate, fumarate, and C_18:2 (control). Two grams of feed consisting of 1.4 g concentrate and 0.6 g ground alfalfa (DM basis) was also added to the culture solution of each treatment. An in vitro incubation in batch was made anaerobically in a shaking incubator for up to 12 h at 39 °C.The pH of the culture solution was increased (P<0.0001) in M-LA or F-LA treatments from 3 h to 12 h compared with the control and LA treatments. At 12 h incubation, the concentration of total VFA in the culture solution was higher (P<0.01) in M-LA and F-LA than in control and LA treatments. Concentration of C₃ by M-LA and F-LA was increased at 3 h (P<0.01), 6 h (P<0.01) and 12 h (P<0.01) compared with control and LA. However, no difference in C₃ concentration was observed between control and LA, or between M-LA and F-LA. Accumulated total gas produced for up to 12 h incubation was increased (P<0.01) by M-LA or F-LA compared with the control. Accumulated total methane produced for up to 12 h incubation, however, was greatly reduced (P<0.01) by all the supplements compared with control, and its production from M-LA or F-LA was smaller than the LA. The M-LA or F-LA also increased (P<0.05–<0.001) the concentrations of cis9, trans11-CLA for all incubation times and trans10, cis12-CLA at 1 h (P<0.01), 3 h (P<0.05), and 12 h (P<0.05) incubation times compared with LA.It can be concluded that malate and fumarate, as propionate precursors, act as alternative electron sinks and may compete with CH₄ generation and bio-hydrogenation of C_18:2 in the utilization of metabolic H₂. The highest CLA concentration at the early incubation stage (1 h) was accompanied by reduced propionate proportion. Linoleic acid is also considered one of the potential alternatives to suppress CH₄ generation.     

Biochemical properties of a β-mannanase and a β-xylanase produced by Ceriporiopsis subvermispora during biopulping conditions

One mannanase and one of the three xylanases produced by Ceriporiopsis subvermispora grown on Pinus taeda wood chips were characterized. A combination of ion exchange chromatography and SDS-PAGE data revealed the existence of a high-molecular-weight mannanase of 150 kDa that was active against galactoglucomannan and xylan. Its activity was optimal at pH 4.5. The K_m value with galactoglucomannan as substrate was 0.50 mg ml^?1. One xylanase with molecular mass of 79 kDa was also purified and characterized. Its activity was optimal at 60 °C and pH 8.0. Its K_m value with birchwood xylan as substrate was 1.65 mg ml^?1. Both the mannanase and the 79 kDa xylanase displayed relatively high activity on carboxymethyl cellulose. The sensitivity of the xylanase and mannanase to various salts was evaluated. None of the tested salts inhibited the xylanase, but Mn⁺², Fe⁺³, and Cu⁺² were strong inhibitors for the mannanase.     

The effects of NH4+ and NO3− on growth,resource allocation and nitrogen uptake kinetics of Phragmites australis and Glyceria maxima

The effects of NH₄⁺ or NO₃⁻ on growth, resource allocation and nitrogen (N) uptake kinetics of two common helophytes Phragmites australis (Cav.) Trin. ex Steudel and Glyceria maxima (Hartm.) Holmb. were studied in semi steady-state hydroponic cultures. At a steady-state nitrogen availability of 34 μM the growth rate of Phragmites was not affected by the N form (mean RGR = 35.4 mg g⁻¹ d⁻¹), whereas the growth rate of Glyceria was 16% higher in NH₄⁺-N cultures than in NO₃⁻-N cultures (mean = 66.7 and 57.4 mg g⁻¹ d⁻¹ of NH₄⁺ and NO₃⁻ treated plants, respectively). Phragmites and Glyceria had higher S/R ratio in NH₄⁺ cultures than in NO₃⁻ cultures, 123.5 and 129.7%, respectively.Species differed in the nitrogen utilisation. In Glyceria, the relative tissue N content was higher than in Phragmites and was increased in NH₄⁺ treated plants by 16%. The tissue NH₄⁺ concentration (mean = 1.6 μmol g fresh wt⁻¹) was not affected by N treatment, whereas NO₃⁻ contents were higher in NO₃⁻ (mean = 1.5 μmol g fresh wt⁻¹) than in NH₄⁺ (mean = 0.4 μmol g fresh wt⁻¹) treated plants. In Phragmites, NH₄⁺ (mean = 1.6 μmol g fresh wt⁻¹) and NO₃⁻ (mean = 0.2 μmol g fresh wt⁻¹) contents were not affected by the N regime. Species did not differ in NH₄⁺ (mean = 56.5 μmol g⁻¹ root dry wt h⁻¹) and NO₃⁻ (mean = 34.5 μmol g⁻¹ root dry wt h⁻¹) maximum uptake rates (V_max), and V_max for NH₄⁺ uptake was not affected by N treatment. The uptake rate of NO₃⁻ was low in NH₄⁺ treated plants, and an induction phase for NO₃⁻ was observed in NH₄⁺ treated Phragmites but not in Glyceria. Phragmites had low K_m (mean = 4.5 μM) and high affinity (10.3 l g⁻¹ root dry wt h⁻¹) for both ions compared to Glyceria (K_m = 6.3 μM, affinity = 8.0 l g⁻¹ root dry wt h⁻¹). The results showed different plasticity of Phragmites and Glyceria toward N source. The positive response to NH₄⁺-N source may participates in the observed success of Glyceria at NH₄⁺ rich sites, although other factors have to be considered. Higher plasticity of Phragmites toward low nutrient availability may favour this species at oligotrophic sites.     

Effect of peppermint (Mentha piperita) oil on in vitro methanogenesis and fermentation of feed with buffalo rumen liquor

The effect of inclusion of peppermint (Mentha piperita) oil (at 0, 0.33, 1.0 and 2.0 μl/ml of incubation medium) on gas and methane production, fermentation of feed and microbial profile was studied in in vitro gas production test, using 200 mg of wheat straw and concentrate mixture in equal proportion as substrate in a 100 ml graduated syringe. The buffalo rumen liquor was used as inoculum and the observations were recorded at 24 h of incubation. Methane emission was reduced (P<0.001) by 19.9%, 46.0% and 75.6% at 0.33, 1.0 and 2.0 μl levels, respectively. The concentration (mM/100 ml) of total volatile fatty acids was reduced (P<0.01) by inclusion of peppermint oil at higher levels (1.0 and 2.0 μl) whereas at 0.33 μl level there was no effect. The proportion of acetate increased (P<0.05) and that of propionate decreased (P<0.001) at 1.0 and 2.0 μl levels of peppermint oil. There was a fall (P<0.001) in carboxymethylcellulase and xylanase activities and the inhibition increased with the increasing level of peppermint oil which resulted in a dose dependent decrease (P<0.05) in in vitro true digestibility of feed. At 0.33 μl level of peppermint oil, the population density of total bacteria was similar to that of control but fungi, Ruminococcus flavefaciens and methanogens increased by 4-, 6- and 2-folds, respectively, as determined with real-time PCR. At 1.0 and 2.0 μl levels the population density of total bacteria, fungi, Fibrobacter succinogens and methanogens decreased drastically and fell below the control values. The numbers of holotrichs and spirotrichs were reduced (P<0.001) by increasing dose of peppermint oil. The higher doses of peppermint oil were toxic for the rumen microbes but the lower levels could be further explored in in vivo experiments as rumen modifier to reduce methanogenesis.     

The effect of benzoic acid concentration on nitrogen metabolism,manure ammonia and odour emissions in finishing pigs

A complete randomised block design experiment was conducted to investigate the effects of benzoic acid inclusion level on nitrogen (N) metabolism, and manure ammonia (NH₃) and odour emissions in finishing pigs. Sixteen boars (64 kg live weight ± 1.5 kg) were assigned to one of four dietary treatments (T) varying in benzoic acid concentration: (T1) 0 g benzoic acid/kg (as fed); (T2) 10 g benzoic acid/kg; (T3) 20 g benzoic acid/kg; (T4) 30 g benzoic acid/kg. Animals were housed in individual metabolism crates and feed was provided ad libitum. All diets were formulated to have similar concentration of digestible energy and ileal digestible lysine with benzoic acid replacing wheat in the diet. There was a linear decrease in NH₃ emission (P<0.001), as the dietary benzoic acid concentration increased (141.4 mg/g versus 40.5 mg/g N intake (S.E.M. 12.1) over the 240-h storage period). However, there was no effect (P>0.05) of benzoic acid on odour concentration. Urinary nitrogen (N) excretion, total N excretion and the urinary:faecal N ratio were linearly reduced (P<0.05) with increasing benzoic acid inclusion. Furthermore, N retention increased linearly (P<0.05) as benzoic acid concentration increased from 0 g/kg to 30 g/kg in the diet. In conclusion, the inclusion of benzoic acid in the diet of finishing pigs has the potential to reduce total and urinary N excretion and the urinary to faecal N ratio. This was mirrored by reductions in manure NH₃ emissions in the benzoic acid supplemented treatments.     

Glucose isomerase production on a xylan-based medium by Bacillus thermoantarcticus

Effects of medium components on intracellular glucose isomerase (GI) production were investigated by Bacillus thermoantarcticus. The highest GI activity was obtained as 1630 U dm^?3 in the medium containing (g dm^?3): 10.6, birchwood-xylan; 5.6, yeast extract; 5.9 (NH₄)₂SO₄ at T = 55 °C in 33 cm^?3 shake-flasks. When birchwood-xylan was replaced with oat spelt- or beechwood-xylan, GI activity decreased to 1372 and 1308 U dm^?3, respectively. Effects of pH at uncontrolled-pH (pH_UC = 6.0) and controlled-pH (pH_C = 6.0) operations, and oxygen transfer at the air inlet rate of 0.5 vvm and agitation rates of 300, 500 and 700 min^?1, were investigated in 3.0 dm³ bioreactor system with 1.65 dm³ working volume in the designed medium. The highest GI activity was attained at 500 min^?1, 0.5 vvm, pH_UC = 6 as 1840 U dm^?3 where cell concentration was 2.3 g dm^?3. The use of agricultural waste xylan, as the carbon source resulted in concomitant production of xylanase and GI. The highest xylanase activity was attained as 9300 U dm^?3 at 500 min^?1 and 0.5 vvm. K_La varied between 0.008–0.033 s^?1 whereas the highest oxygen uptake rate was 0.002 mmol dm^?3 s^?1. Initially biochemical reaction limitations were effective; thereafter, mass transfer resistances became more effective.     

Effects of supplemental urea sources and feeding frequency on ruminal fermentation,fiber digestion,and nitrogen balance in beef steers

The objective of two experiments was to evaluate non-protein N supplementation with protected urea sources in terms of rumen fermentation products, nutrient digestibility, and N balance in ruminally fistulated beef steers (initial bodyweight 239 ± 18 kg) fed switchgrass hay. Experiment 1 compared urea with Optigen II^®, and Experiment 2 compared urea with RumaPro^®. In both experiments, supplements (400 g/kg of daily dietary dry matter) were fed once daily or every 2 h in a balanced design. Supplements contained soybean hulls, corn grain, vitamins, and minerals as well as non-protein N sources. Non-protein N provided 0.18 g/g of dietary N. Switchgrass hay was fed once daily, at the same time as the supplement in the once-daily treatments. Dry matter intake (4.1 kg/d in Experiment 1, 4.5 kg/d in Experiment 2), dry matter digestibility (P<0.25, 0.58 ± 0.014 g/g in Experiment 1, 0.58 ± 0.010 g/g in Experiment 2), N balance (P<0.83, 11.3 ± 1.9 g/d in Experiment 1, 11.8 ± 3.6 g/d in Experiment 2), ruminal ammonia concentrations (P<0.29, 15.2 ± 1.4 mM in Experiment 1, 11.8 ± 0.6 mM in Experiment 2), and ruminal short-chain fatty acid concentrations (P<0.13, 77.7 ± 3.0 mM in Experiment 1, 75.4 ± 3.0 mM in Experiment 2) were not affected by feeding protected urea sources. Providing a steady supply of ruminally degradable N by feeding supplement every 2 h vs once daily decreased ruminal ammonia concentrations by approximately one-half by 4 h after feeding hay (P<0.01 in both experiments) and increased (P<0.02 in Experiment 1, P<0.08) in Experiment 2) apparent digestibility of dry matter (0.58–0.62 in Experiment 1, 0.56–0.61 in Experiment 2) and dietary fiber components.     

Soil nitrate accumulation explains the nonlinear responses of soil CO2 and CH4 fluxes to nitrogen addition in a temperate needle-broadleaved mixed forest

The responses of soil-atmosphere carbon (C) exchange fluxes to growing atmospheric nitrogen (N) deposition are controversial, leading to large uncertainty in the estimated C sink of global forest ecosystems experiencing substantial N inputs. However, it is challenging to quantify critical load of N input for the alteration of the soil C fluxes, and what factors controlled the changes in soil CO₂ and CH₄ fluxes under N enrichment. Nine levels of urea addition experiment (0, 10, 20, 40, 60, 80, 100, 120, 140 kg N ha⁻¹ yr⁻¹) were conducted in the needle-broadleaved mixed forest in Changbai Mountain, Northeast China. Soil CO₂ and CH₄ fluxes were monitored weekly using the static chamber and gas chromatograph technique. Environmental variables (soil temperature and moisture in the 0–10 cm depth) and dissolved N (NH₄⁺-N, NO₃⁻-N, total dissolved N (TDN), and dissolved organic N (DON)) in the organic layer and the 0–10 cm mineral soil layer were simultaneously measured. High rates of N addition (≥60 kg N ha⁻¹ yr⁻¹) significantly increased soil NO₃⁻-N contents in the organic layer and the mineral layer by 120%-180% and 56.4%-84.6%, respectively. However, N application did not lead to a significant accumulation of soil NH₄⁺-N contents in the two soil layers except for a few treatments. N addition at a low rate of 10 kg N ha⁻¹ yr⁻¹ significantly stimulated, whereas high rate of N addition (140 kg N ha⁻¹ yr⁻¹) significantly inhibited soil CO₂ emission and CH₄ uptake. Significant negative relationships were observed between changes in soil CO₂ emission and CH₄ uptake and changes in soil NO₃⁻-N and moisture contents under N enrichment. These results suggest that soil nitrification and NO₃⁻-N accumulation could be important regulators of soil CO₂ emission and CH₄ uptake in the temperate needle-broadleaved mixed forest. The nonlinear responses to exogenous N inputs and the critical level of N in terms of soil C fluxes should be considered in the ecological process models and ecosystem management.     

Response in root morphology and nutrient contents of Myriophyllum spicatum to sediment type

Sediment may play an important role during the submerged macrophyte decline in the eutrophication progress. In order to investigate the response in root morphology and nutrient contents of submerged macrophytes Myriophyllum spicatum to sediment, five sediment types were treated and used (five types of sediment were used in the experiment: treatment 1 was nature sediment + sand, a 50:50 (v/v) mixture, treatment 2 was the studied sediment only, treatment 3 was sediment + nitrogen (N, NH₄Cl 400 mg kg^?1), treatment 4 was sediment + phosphorus (P, NaH₂PO₄ 300 mg kg^?1); treatment 5 was sediment + phosphorus (P, NaH₂PO₄ 600 mg kg^?1)). The results show that the root N content was only significantly affected by adding N in sediments and P was elevated by adding N and P. The root mass and its percentage increased at first, the peak values were reached at 35 d, and then decreased. The root growth was restrained by adding sand and N in sediments, root senescence process was delayed at the later experimental time by adding P in sediments. The increase of root volume showed a similar trend to that of root growth, except for plant with P addition where root volume remained high after 35 d. The root volume decreased while the main root number increased significantly by adding sand in sediments. The mean root length and main root diameter were reduced by adding P in sediments. The compatible sediment nutrient condition is necessary to restore submerged macrophytes in a degraded shallow lake ecosystem, and the effect of sediment on the root morphology and nutrient content is one of the important aspects restricting the restoration of submerged macrophytes.     

Protective effect of β-casomorphin-7 on cardiomyopathy of streptozotocin-induced diabetic rats via inhibition of hyperglycemia and oxidative stress

β-Casomorphin-7 (β-CM-7) is regarded as the most representative milk-derived bioactive peptide. The present work studies the efficacy of β-CM-7 against myocardial injury in streptozotocin-induced diabetic rats, focusing on the following assays: (1) the level of blood glucose and advanced glycosylation end product (AGE), the activity of lactate dehydrogenase (LDH) in serum; (2) the level of hydrogen peroxide (H₂O₂), the activity of Na⁺K⁺-ATPase, Ca²⁺Mg²⁺-ATPase and enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) in myocardial tissue; (3) the protein expression of glucose transporter-4 (GLUT-4) in myocardial tissue. It showed that with the influence of β-CM-7, the levels of blood glucose of β-CM-7 treatment group decreased markedly compared with model group (P < 0.01) accompanied with their alleviated symptoms of diabetes. In the antioxidant and oxidant levels, β-CM-7 treatment group signified a remarkable increase in the activity of GSH-Px, SOD and CAT of the anti-oxidation system and meanwhile demonstrated a considerable reduction in H₂O₂ content (all P < 0.05) in comparison with model group. We also found both the content of AGE and the activity of LDH of β-CM-7 treated group considerably reduced while the content of GLUT-4 and the activity of Na⁺K⁺-ATPase and Ca²⁺Mg²⁺-ATPase of β-CM-7 treated group increased obviously (P < 0.05). Meanwhile the cardiac indexes were significantly lessened. Thus our assay validates that the remedy employing β-CM-7 may treat diabetic cardiomyopathy with high efficacy predominantly associated with the mechanism that β-CM-7 ameliorates myocardial energy metabolism and abates free-radical-mediated oxidative stress in blood and myocardium.     

Plasma levels of intermedin (adrenomedullin-2) in healthy human volunteers and patients with heart failure

Intermedin/adrenomedullin-2 (IMD) is a member of the adrenomedullin/CGRP peptide family. Less is known about the distribution of IMD than for other family members within the mammalian cardiovascular system, particularly in humans. The aim was to evaluate plasma IMD levels in healthy subjects and patients with chronic heart failure. IMD and its precursor fragments, preproIMD_25–56 and preproIMD_57–92, were measured by radioimmunoassay in 75 healthy subjects and levels of IMD were also compared to those of adrenomedullin (AM) and mid-region proadrenomedullin_45–92 (MRproAM_45–92) in 19 patients with systolic heart failure (LVEF < 45%). In healthy subjects, plasma levels (mean + SE) of IMD (6.3 + 0.6 pg ml⁻¹) were lower than, but correlated with those of AM (25.8 + 1.8 pg ml⁻¹; r = 0.49, p < 0.001). Plasma preproIMD_25–56 (39.6 + 3.1 pg ml⁻¹), preproIMD_57–92 (25.9 + 3.8 pg ml⁻¹) and MRproAM_45–92 (200.2 + 6.7 pg ml⁻¹) were greater than their respective bioactive peptides. IMD levels correlated positively with BMI but not age, and were elevated in heart failure (9.8 + 1.3 pg ml⁻¹, p < 0.05), similarly to MRproAM_45–92 (329.5 + 41.9 pg ml⁻¹, p < 0.001) and AM (56.8 + 10.9 pg ml⁻¹, p < 0.01). IMD levels were greater in heart failure patients with concomitant renal impairment (11.3 + 1.8 pg ml⁻¹) than those without (6.5 + 1.0 pg ml⁻¹; p < 0.05). IMD and AM were greater in patients receiving submaximal compared with maximal heart failure drug therapy and were decreased after 6 months of cardiac resynchronization therapy. In conclusion, IMD is present in the plasma of healthy subjects less abundantly than AM, but is similarly correlated weakly with BMI. IMD levels are elevated in heart failure, especially with concomitant renal impairment, and tend to be reduced by high intensity drug or pacing therapy.     

Assessment of the efficacy of varying experimental exogenous fibrolytic enzymes using in vitro fermentation characteristics

This study evaluated a series of recombinant, single activity experimental enzyme products including 13 endoglucanases (END) and 10 xylanases (XY), for their potential to improve in vitro ruminal degradation of alfalfa hay in two experiments. Based on the endoglucanase or xylanase enzymatic activities measured using complex substrates at the optimal conditions (pH 5.4, 37 °C) for the enzymes, a dose level (1 unit/g dry matter [DM]) was chosen for addition of enzymes to substrate. Enzyme products, re-suspended with water, were added to alfalfa hay (0.5 or 1.0 g DM) in culture vials in six replications. Anaerobic buffer medium (20 or 40 ml) adjusted to pH 6.0 and strained ruminal fluid (5 or 10 ml) were sequentially added to the vials and incubated for 18 h. Headspace gas production (GP) was measured throughout the incubation, and degradability of organic matter (OMD) and fibre and volatile fatty acid (VFA) concentrations were determined after 18 h of incubation. The enzyme products had a wide range of added endoglucanase or xylanase activities when determined using pure substrates and physiological conditions typical of the rumen (pH 6.0, 39 °C). In experiment 1, many END, and some XY, products increased GP and OMD. The correlation between added endoglucanase activity determined at ruminal conditions and OMD improvement was high (r = 0.71; P<0.01), whereas added activity of xylanase was not associated with OMD improvement. Two END and two XY products selected from experiment 1 were further assessed because they substantially improved GP and OMD. In experiment 2, all enzyme treatments, alone or in combination, increased total GP and DM and fibre degradabilities (P<0.05). However, the combinations of END and XY did not increase degradation of alfalfa beyond that of the component enzymes. Total VFA production was not affected by enzyme treatments although some products changed the acetate to propionate ratio. Experimental exogenous enzyme products with either endoglucanase or xylanase activity substantially improved in vitro ruminal degradation of alfalfa hay, but further improvement by combining these activities did not occur.     

The effects of calcium sulphate on growth,membrane stability and nutrient uptake of tomato plants grown under salt stress

A pot experiment was carried out with tomato (Lycopersicon esculentum Mill.) cv. “Target F1” in a mixture of peat, perlite, and sand (1:1:1) to investigate the effects of supplementary calcium sulphate on plants grown at high NaCl concentration (75 mM). The treatments were: (i) control (C), nutrient solution alone; (ii) salt treatment (C + S), 75 mM NaCl; (iii) salt plus calcium treatment 1 (C + S + Ca1), 75 mM NaCl plus additional mixture of 2.5 mM CaSO₄ in nutrient solution; (iv) salt plus calcium treatment 2 (C + S + Ca2), 75 mM NaCl plus additional mixture of 5 mM CaSO₄ in nutrient solution. The plants grown under salt stress produced low dry matter, fruit weight, and relative water content than those grown in standard nutrient solution. Supplemental calcium sulphate added to nutrient solution containing salt significantly improved growth and physiological variables affected by salt stress (e.g. plant growth, fruit yield, and membrane permeability) and also increased leaf K⁺, Ca²⁺, and N in tomato plants. The effects of supplemental CaSO₄ in maintaining membrane permeability, increasing concentrations of Ca²⁺, N, and K⁺ and reducing concentration of Na⁺ (because of cation competition in root zone) in leaves could offer an economical and simple solution to tomato crop production problems caused by high salinity.     

Carbon and nitrogen metabolism of an eutrophication tolerative macrophyte,Potamogeton crispus,under NH4+ stress and low light availability

Submersed macrophytes in eutrophic lakes often experience high NH₄⁺ concentration and low light availability in the water column. This study found that an NH₄⁺–N concentration of 1 mg L^?1 in the water column apparently caused physiological stress on the macrophyte Potamogeton crispus L. The plants accumulated free amino acids (FAA) and lost soluble carbohydrates (SC) under NH₄⁺ stress. These stressful effects of NH₄⁺ were exacerbated under low light availability. Shading significantly increased NH₄⁺ and FAA contents and dramatically decreased SC and starch contents in the plant shoots. At an NH₄⁺–N concentration of 1 mg L^?1 in the water column, neither growth inhibition nor NH₄⁺ accumulation was observed in the plant tissues of P. crispus under normal light availability. The results showed that 1 mg L^?1 NH₄⁺–N in the water column was not toxic to P. crispus in a short term. To avoid NH₄⁺ toxicity, active NH₄⁺ transportation out of the cell may cost energy and thus result in a decline of carbohydrate. When NH₄⁺ inescapably accumulates in the plant cell, i.e. under NH₄⁺ stress and shading, NH₄⁺ is scavenged by FAA synthesis.     

Ionic luminescent cyclometalated Ir(III) complexes with polypyridine co-ligands

Two novel ligands containing a functionalized N ∧ N chelating moiety (pbpy-OBut and tpy-COOH, respectively) were treated with [Ir(ppy)₂(μ-Cl)]₂ (ppy = 2-(2-pyridyl)phenyl), leading to the cationic cyclometalated complexes [Ir(ppy)₂(pbpy-OBut)]⁺ (2) (pbpy-OBut = 4-{4′-(4-phenyloxy)-6′-phenyl-2,2′-bipyridyl}butene) and [Ir(ppy)₂(tpy-COOH)]⁺ (3) (tpy-COOH = 4′-(4-carboxyphenyl)-2,2′:6′,2″-terpyridine). Complexes 2 and 3 exhibit intense room temperature luminescence both in solution and as solid films. Assignment of the emissive behavior to a ³LLCT (ppy-to-N ∧ N) excited state is proposed.