Nutritional characterization of Mucuna pruiriens: 2. In vitro ruminal fluid fermentability of Mucuna pruriens,Mucunal-dopa and soybean meal incubated with or without l-dopa

Three in vitro experiments were conducted to determine the rumen fermentability of Mucuna (M) pruriens (24 g 3,4-dihydroxy-l-phenylalanine (l-dopa)/kg dry matter (DM) and soybean meal treated with (SBD) or without (SB) 138 g l-dopa/kg DM). Additional objectives were to determine if l-dopa inhibits rumen fermentation, and if ruminal microbes can adapt to l-dopa or M. In Experiment 1, ground (1 mm) substrates were incubated in triplicate at 38 °C in 9 ml nutrient media and 1 ml rumen fluid in a series of six, 48 h, consecutive batch cultures. The first culture was inoculated with rumen fluid from two donor cows. Subsequent cultures were inoculated with fluid (1 ml) from the previous culture. The DM digestibility (DMD, 616 g/kg vs. 540 g/kg; P<0.01) and gas production (51.7 ml/g vs. 44.2 ml/g DM; P<0.05) were higher from fermentation of M versus SB but similar for SB and SBD (540 g/kg vs. 554 g/kg and 44.2 ml/g DM vs. 43.5 ml/g DM, respectively). The slopes of the relationships between DMD (g/kg) or gas production (ml/g DM) and fermentation period were not reduced by fermenting M (−0.014 DMD slope; 2.28 gas production slope) or SBD (−0.014 DMD slope; 0.459 gas production slope), instead of SB (−0.002 DMD slope; 1.039 gas production slope), indicating microbial adaptation to M and SBD. Total volatile fatty acid concentration (VFA; 53.7, 54.9 and 54.9 mmol/l) and molar proportions of VFA were similar among substrates. Gas production kinetics of M versus SB (Experiment 2), and SB versus SBD (Experiment 3) were also measured after substrates were incubated in triplicate in buffered rumen fluid for 24 h using a non-linear exponential model to fit the data. Residual l-dopa was measured after separate fermentation of substrates in triplicate for 0, 4, 8, 16 and 24 h. Fermentation of M versus SB produced more (P<0.05) gas (250 ml/g vs. 100 ml/g DM) and total VFA (203 mmol/l vs. 180 mmol/l) and a lower (P<0.05) acetate:propionate ratio (1.35 vs. 1.87; P<0.05). Adding l-dopa to SB increased (P<0.01) gas production (92 ml/g DM vs. 200 ml/g DM), and total VFA concentration (132 mmol/l vs. 188 mmol/l), but reduced (P<0.05) gas production rate (0.08 ml/h vs. 0.05 ml/h). The concentration of l-dopa in fermented M and SBD decreased by 53 and 47%, respectively during fermentation. In conclusion, M was more fermented than SB and degradation of l-dopa during ruminal fermentation and microbial adaptation to l-dopa were confirmed. Adding l-dopa to SB did not impair ruminal fermentation.     

Effects of NaOH treatment on condensed tannin contents and gas production kinetics of tree leaves

Effects of NaOH treatment on the crude protein (CP), condensed tannin (CT) and in vitro gas production kinetics of leaves of Arbutus andrachne, Glycyrrhiza glabra L. and wheat straw were determined. Wheat straw, which is tannin-free, was used as the standard. The NaOH treatment was completed by pulverization of samples with 0, 20, 40, 60 and 80 g/L of NaOH solution in the proportion of 1 L of solution to 1 kg of sample. Gas production was determined at 3, 6, 12, 24, 48, 72 and 96 h of incubation. NaOH treatment linearly decreased (P<0.001) the CT contents of leaves of Arbutus andrachne and Glycyrrhiza glabra L. whereas NaOH treatment had no effect on the CP contents of Arbutus andrachne, Glycyrrhiza glabra L. and wheat straw. The 80 g/L NaOH treatment reduced the CT content of leaves of Arbutus andrachne and Glycyrrhiza glabra L. by 59.6% and 86.7%, respectively. NaOH treatment linearly decreased (P<0.01) gas production rate of Arbutus andrachne although it linearly increased (P<0.01) gas production rate of wheat straw. In contrast, NaOH treatment had no effect on gas production rate of leaves of Glycyrrhiza glabra L. NaOH treatment linearly decreased (P<0.001) potential gas production of leaves of Arbutus andrachne and Glycyrrhiza glabra L. whereas NaOH treatment linearly increased (P<0.001) potential gas production of wheat straw. Treatment with NaOH can be used to improve the nutritive value of tannin-free forages such as straw, but not for tannin-containing leaves.     

Effects of Yucca schidigera and Quillaja saponaria with or without β 1–4 galacto-oligosaccharides on ruminal fermentation,methane production and nitrogen utilization in sheep

Effects of Quillaja saponaria extract (QSE) and Yucca schidigera extract (YSE) with or without β 1–4 galacto-oligosaccharides (GOS) on ruminal fermentation, methane production and N utilization in wether sheep were evaluated. Four wethers fitted with permanent ruminal fistulae were assigned in a 4 × 6 Youden square design experiment and fed a basal diet comprised of concentrate and Italian ryegrass hay (2:3, on a DM basis) at 55 g/kg metabolic body weight. Treatments were: (1) control (no addition of supplement); (2) 14 ml of QSE; (3) 14 ml of YSE; (4) 20 g of GOS; (5) 14 ml QSE + 20 g GOS; (6) 14 ml YSE + 20 GOS per day. Digestibility of NDFom increased (P<0.05) in sheep treated with QSE, QSE + GOS, and YSE + GOS, but was not affected by YSE or GOS. Ruminal fluid pH increased (P<0.05) in sheep administered with YSE compared with other treatments. Ammonia N and total VFA concentrations declined (P<0.001) with administration of QSE and YSE compared with the control. Propionate and acetate molar proportions were not affected, while butyrate molar proportion declined (P<0.001) with QSE alone or in combination with GOS. Digestible energy increased (P<0.05) with all treatments, except YSE. Results suggest that administration of QSE and YSE reduced ruminal ammonia N and total VFA concentration, and numerically decreased methane emissions, without having adverse effects on fiber digestion. In addition, administration of YSE, with or without GOS, numerically reduced protozoal numbers. QSE, YSE and YSE + GOS may have potential as beneficial manipulators of ruminal fermentation.     

Effect of harvest date and nitrogen fertilization rate on the nutritive value of amaranth forage (Amaranthus hypochondriacus)

This study was conducted to assess effects of harvest date (i.e., 40 and 60 d after planting) and N fertilization rate (i.e., 120, 180, 240 kg N/ha) on the nutritive value of amaranth forage (Amaranthus hypochondriacus) using a factorial experiment with a randomized complete block design. The content of dry matter (DM), crude protein (CP), true protein (TP), ether extract (EE), water soluble carbohydrates (WSC), ash-free neutral detergent fiber (NDFom), ash-free acid detergent fiber (ADFom), lignin(sa), ash, Ca, P, Na, K, oxalic acid and nitrate were determined. Soluble CP (SP) and protein fractions non-protein N (A), true protein rapidly degraded in the rumen (B₁), true protein degraded in the rumen at a moderate rate (B₂), true protein associated with the cell wall and slowly degraded in the rumen (B₃) and acid detergent insoluble CP (C) were measured according to the Cornell Net Carbohydrate and Protein System. In vitro gas production (IVGP), OM disappearance (OMD) and NDFom disappearance (NDFD) were determined using a gas production technique. Results showed that the later harvest date increased (P<0.05) DM, EE, WSC, NDFom, ADFom, lignin(sa), B₃ and C; while CP, TP, ash, Ca, P, K, SP, A, B₁, B₂, nitrate, total and soluble oxalic acid, IVGP, b (i.e., gas production from the insoluble fermentable fractions at 120 h), c (i.e., rate of gas production during incubation), OMD and NDFD decreased (P<0.05). With increasing N fertilization rate, CP, TP, EE, P, nitrate, oxalic acid, SP, A, b, OMD and NDFD increased (P<0.05), however B₂ declined (P<0.05). Increasing N fertilization increased yield, CP concentration and nutrient digestibility. At 40 d after planting use of amaranth forage as a ruminant feed is limited due to its high nitrate content. However, at 60 d, although a depression in digestibility and CP content occurred, this forage has the potential as a ruminant feed due to the much lower nitrate levels.     

Influence of urea calcium mixture supplementation on ruminal fermentation characteristics of beef cattle fed on concentrates containing high levels of cassava chips and rice straw

The purpose of this study was to evaluate the effects of various N sources in concentrates containing high levels of cassava chips, with rice straw as the basal forage, on rumen ecology, rumen microbial counts, microbial crude (CP) protein synthesis, and digestibility of nutrients. Four ruminally fistulated crossbred (Brahman × native) beef steers with initial body weight (BW) of 400 ± 40.2 kg were randomly assigned according to a 4 × 4 Latin square design. The dietary treatments were different sources of N in the concentrates and were: T1 = urea (control; urea); T2 = soybean meal (SBM); T3 = urea CaCl₂ mixture (U-Cal); T4 = urea CaSO₄ mixture (U-Cas). All steers were kept in individual pens and supplemented with concentrate at 5 g/kg of BW daily. The experiment was 4 periods, and each lasted 21 d. During the first 14 d, all steers were fed their respective diets ad libitum and for during the last 7 d, they were moved to metabolism crates for total urine and fecal collection. Dry matter intake ranged from 9.8 to 10.5 kg daily and was not altered by diet, while digestibility of NDF differed among treatments and was highest with U-Cas supplementation (P<0.05). Ruminal NH₃ N and plasma urea N with U-Cal, U-Cas, and SBM diets were lower compared with the urea supplemented group (P<0.05). Ruminal volatile fatty acid concentrations were not altered by treatments. Total viable, and cellulolytic bacteria, differed among treatments and were highest with U-Cas (9.1 × 10¹¹, and 4.0 × 10⁹ cfu/mL, respectively). In addition, efficiency of rumen microbial CP synthesis based on organic matter (OM) truly digested in the rumen was increased by SBM or U-Cal supplementation, and was highest with U-Cas supplementation (18.2 g of N/kg of OM truly digested in the rumen). Supplementation of U-Cas to a concentrate containing a high level of cassava chips improved rumen ecology and microbial CP synthesis in beef cattle, suggesting that urea calcium mixtures can replace soybean meal or urea in beef cattle diets without adverse affects on rumen fermentation and other rumen parameters.     

Seasonal variations in the chemical composition and dry matter degradability of exclosure forages in the semi-arid region of northern Ethiopia

The present study was conduced at two sites (Tembien and Wukro) in the semi-arid region of Tigray in northern Ethiopia to investigate the seasonal dynamics in the chemical composition and dry matter digestibility of grass and browse species of exclosures. The browse species studied in Tembien and Wukro had a mean crude protein (CP) value of 166 and 117 g/kg dry matter (DM), respectively. The mean in vitro dry matter digestibility (IVDMD) coefficient and predicted metabolizable energy (ME) density of the browse species were 0.72 and 9.83 MJ/kg DM, respectively at Tembien, 0.62 and 8.38 MJ/kg DM, respectively, at Wukro. Neutral detergent fibre (NDF) and acid detergent fibre (ADF) values of the browse species varied from 192 to 437 and 127 to 391 g/kg DM, respectively. Acid detergent lignin (ADL) values ranged from 36 to 190 g/kg DM. The mean CP of the grass species in Tembien and Wukro during the long rainy season was 76 and 73 g/kg DM, respectively and values declined below a critical maintenance level during the dry and short rain seasons. Mean IVDMD and ME values for the two sites were 0.41 and 0.47, and 5.38 and 6.11 MJ/kg DM, respectively. The NDF, ADF, and lignin values of the grass species were generally above 700, 400, and 70 g/kg DM, respectively. The CP, IVDMD and ME values of the mixed grass samples differed (P<0.05) among harvesting months and values ranged from 20 to 103 g/kg DM, 0.47 to 0.72 MJ/kg DM, and 6.16 to 9.91 MJ/kg DM, respectively. The browse species could be used as useful dry season protein supplements to the N deficient native grass species. Especial emphasis should be given to propagate Maerua angolensis and Cadaba farinosa at community nursery sites. Harvesting in September, rather than the current extended harvest period that took place in October and November, can considerably improve the feeding value of native grass hay for smallholder ruminant production systems.     

Citric acid improves growth performance and phosphorus digestibility in Beluga (Huso huso) fed diets where soybean meal partly replaced fish meal

A 2 × 3 factorial experiment was conducted to evaluate the effect of partial substitution of dietary fish meal with soybean meal and citric acid (CA) supplementation on growth, food utilization, muscle composition and nutrient digestibility of Beluga, Huso huso. Three isonitrogenic and isoenergetic diets, as SBM₁ (soybean meal protein (SBP):fishmeal protein (FP) = 1:3), SBM₂ (SBP:FP = 2:3) and SBM₃ (SBP:FP = 1:1) containing two levels of CA (0 and 30 g kg⁻¹) were fed to triplicate groups of fish for 8 weeks. The results revealed that adding CA increased (P<0.05) the weight gain (WG), specific growth rate (SGR) and protein efficiency ratio (PER) and decreased (P<0.05) food conversion rate (FCR) whereas partial substitution of fishmeal with soybean meal decreased (P<0.05) growth performance. Partial replacement of fishmeal with SBM (P=0.021) as well as CA supplementation (P=0.019) and their interaction (P<0.001) affected hepatosomatic index (HSI). No differences (P>0.05) were observed for viscerosomatic index (VSI) among treatments (P>0.05). No differences (P>0.05) were detected in moisture, protein of muscle sample among treatments, but lipid content was reduced (P<0.05) while ash content increased (P=0.035) by CA. Soybean meal decreased (P<0.05) nutrient digestibility, whereas CA improved apparent protein and phosphorus (P) digestibility (P=0.011 and P<0.001 respectively). No interaction (P<0.05) between levels of SBM and CA was found on these parameters. Results of the present study indicate that Beluga has a limited ability to utilize SBM as a protein source in practical diets whereas CA can improve growth and nutrient utilization in Beluga.     

Rapid down-regulation of mitochondrial fat metabolism in human muscle after training cessation is dissociated from changes in insulin sensitivity

The association between impairment in mitochondrial muscle fat oxidative capacity (OX_FA) and occurrence of insulin resistance was examined in 14 healthy trained men (age, 24 ± 4 yr) submitted to 4 weeks of training cessation. Training stop induced a significant decrease in mRNA levels of proteins involved in muscle fat metabolism, particularly PPARα (−58%, P < 0.01) and PGC-1α (−30%, P < 0.05), a 21% reduction in OX_FA (P < 0.01), and reduced fat oxidation during moderately intense exercise (P < 0.05). In contrast, there was no significant alteration in insulin sensitivity. In conclusion, decline in OX_FA is a rapid metabolic event following training cessation. It is involved in the regulation of whole body fat balance but not in the deterioration of insulin sensitivity.     

Effect of feed restriction or feeding high-fibre diet during the rearing period on body composition, serum parameters and productive performance of rabbit does

This study evaluated the effect of different feeding regimes from 11 weeks of age to first parturition on feed intake, leptin, non-esterified fatty acids (NEFA) and total protein serum levels, as well as productive performance in young rabbit does. In addition, body composition was estimated by bioimpedance analysis. Thirty-six 11-week-old does were randomly distributed in three groups. The AL-C group was fed ad libitum a control diet containing 350 g neutral detergent fibre (aNDFom)/kg, 11.6 MJ digestible energy (DE)/kg and 173 g crude protein (CP)/kg, and the does were inseminated at 16 weeks of age. The R-C group was fed 150 g/d of the same diet until 16 weeks of age, one week before artificial insemination (AI) at 17 weeks of age, and then fed ad libitum. The AL-F group was fed a diet containing 475 g aNDFom/kg, 9.4 MJ DE/kg and 174 g CP/kg ad libitum, and was inseminated at 17 weeks of age. During rearing (11-16 weeks), does in the R-C group had the lowest DE (1.54 MJ/d; P<0.003) and digestible protein (DP, 17.9 g/d; P<0.001) intake, as well as the lowest protein (172 g/kg; P<0.05) and energy (5.9 MJ/kg) body contents, leptin concentration at 16 weeks of age (2.48 ng/ml; P<0.001) and fertility (P<0.02) at first AI. Daily feed intake during pregnancy and lactation, as well as prolificacy and litter weight, were similar among groups. The highest percentage of body fat was observed for all the does when were inseminated for the first time (135 g/kg; P<0.001), consistent with the highest leptin (4.48 ng/ml; P<0.001) and total protein serum levels (6.87 g/dl; P<0.001) at this time. Serum NEFA level around parturition was higher (P<0.05) in groups AL-C and R-C (1.11 and 0.85 mmol/l) than in group AL-F (0.71 mmol/l), suggesting a lower lipid mobilization that tended to improve fertility rate for AL-F does on day 11 post-parturition (P<0.09). In conclusion, feed restriction during the rearing period delays reproductive development in young rabbits. In nulliparous does, ad libitum feeding during rearing with a high-fibre diet allows a similar productive performance to that of feeding with a less fibrous diet. Nevertheless, the use of high fibre diets during rearing does not affect feed intake throughout the first pregnancy and lactation.     

Overexpression of β2AR improves contractile function and cellular survival in rabbit cardiomyocytes under chronic hypoxia

Chronic hypoxia usually evokes sustained release of endogenous neurohormones, leading to β₂-adrenergic receptor (β₂AR) desensitization and downregulation of expression, which impacts cellular contractility. We investigated whether exogenous β₂AR could compensate for the functional deficiency of β₂AR in rabbit cardiomyocytes under chronic hypoxia, and whether this led to improved contractility and cellular survival.A surgical experimental model of cyanotic heart disease was established in rabbits. Adv.hβ₂AR was transfected into cardiomyocytes isolated from animals subjected to 6-week systemic hypoxia. The levels of cellular contractile function, protein expression of hβ₂AR, p-Akt, p-Erk, and caspase-3, and cellular survival pre- and post-Adv.hβ₂AR delivery were determined.In the cyanotic cells, decreased shortening and lengthening of TPC and R50 were evident. Cellular diastolic functioning showed greater deterioration compared to the systolic function (P < 0.05). In cyanotic cells, the positive inotropic response to isoproterenol was decreased (P < 0.01), low levels of cellular survival were found, protein levels of β₂AR, p-Akt, and p-Erk were downregulated, and protein levels of caspase-3 were upregulated. After Adv.hβ₂AR delivery, enhanced contractile function was achieved (P < 0.01), TPC and R50 levels recovered up to 99% and 81.7% of the normal control levels, respectively (P < 0.05), and cellular survival improved (P < 0.01).Our results demonstrate that overexpression of the β₂AR gene in cardiomyocytes exposed to chronic hypoxia provides significant catecholamine-dependent inotropic support and cellular protection.     

Effect of zinc supplementation from two sources on growth,nutrient utilization and immune response in male crossbred cattle (Bos indicus×Bos taurus) bulls

To investigate effects of Zn supplementation on performance, mineral balance and immune response, 15 male crossbred cattle (Bos indicus×Bos taurus) bulls of about 14 ± 0.4 months of age and weighing 226.0 ± 9.1 kg were divided in to three groups of five. Bulls in the control group were fed wheat straw and a concentrate mixture (basal diet with 32.5 mg Zn/kg dry matter (DM)), and in ZnSO₄ and ZnProp groups 35 mg Zn/kg DM was added through Zn sulphate and Zn propionate, respectively. All bulls were fed their respective treatment diets for 180 days. Daily feed intake was recorded and bulls were weighed at every 15 days to determine change in body weight (BW). After 120 days of feeding, bulls were vaccinated with Brucella abortus strain 19, and cell mediated and humoral immune responses were assessed between 120 and 148 days of experimental feeding. After 150 days of feeding, a metabolism study of 6 days duration was completed to determine nutrient digestibility and mineral balances (i.e., Ca, P, Zn, Cu, Fe and Mn). Intake of total DM, digestibility of DM, crude protein, ether extract, neutral detergent fibre and acid detergent fibre, N balance, average daily gain, feed: gain did not differ between the groups. Intake, excretion and balance of Ca, P, Zn, Cu, Fe and Mn also did not differ between the groups. However, retention of Zn was higher (P<0.001) in the ZnProp group. Bulls supplemented with Zn propionate had higher cell mediated (P<0.01) and humoral (P<0.05) immune response, while there was no alteration in immune response due to Zn sulphate supplementation. Results indicate that a diet containing about 32.5 mg Zn/kg DM was adequate to support normal growth and digestibility, but a better immune response occurred when Zn propionate was added to the diet at 35 mg/kg DM versus Zn sulphate.     

Safflower seeds in corn silage and alfalfa hay based early lactation diets: A practice within an optimum forage choice

Safflower seed (SS), Carthamus tinctorius L., has the highest concentration of linoleic acid among 80 oilseeds. It was hypothesized that an Iranian variety of SS can be effectively fed with cottonseeds (CS) to maintain feed intake, energy metabolism and productivity of early lactation cows under negative energy balance. Our objective was to determine effects of feeding diets containing 100 g whole CS with (1) no SS (SS0), (2) 75 g CS + 25 g SS (SS25), or (3) 50 g CS + 50 g SS (SS50), per kg of dietary DM, on feed intake, rumen fermentation, blood metabolites and milk production of early lactation cows fed diets based on a uniform mixtures of alfalfa hay and corn silage. Nine multiparous early lactation Holstein cows (46 ± 7 d in milk) were used in a replicated 3 × 3 Latin square design study with three 21-d periods. Each period had 14 d of adaptation and 7 d of data collection. Dietary inclusion of SS did not affect (P>0.10) DM intake, rumen pH and concentrations of ammonia and VFA, blood concentrations of insulin, non-esterified fatty acids, urea and triglycerides, and milk production. Adding SS linearly reduced blood glucose (P=0.05) and beta-hydroxybutyric acid (P<0.05), and increased blood total cholesterol (P<0.01) and low-density lipoproteins (P<0.05) concentrations. Results demonstrated that SS as an economical and rich source of essential fatty acids can be included up to 50 g/kg of dietary DM alongside CS for early lactation cows without affecting feed intake while maintaining rumen fermentation, peripheral energy supply and milk production.     

Abscisic acid root and leaf concentration in relation to biomass partitioning in salinized tomato plants

Salinization is one of the most important causes of crop productivity reduction in many areas of the world. Mechanisms that control leaf growth and shoot development under the osmotic phase of salinity are still obscure, and opinions differ regarding the Abscisic acid (ABA) role in regulation of biomass allocation under salt stress. ABA concentration in roots and leaves was analyzed in a genotype of processing tomato under two increasing levels of salinity stress for five weeks: 100 mM NaCl (S10) and 150 mM NaCl (S15), to study the effect of ABA changes on leaf gas exchange and dry matter partitioning of this crop under salinity conditions. In S15, salinization decreased dry matter by 78% and induced significant increases of Na⁺ and Cl⁻ in both leaves and roots. Dry matter allocated in different parts of plant was significantly different in salt-stressed treatments, as salinization increased root/shoot ratio 2-fold in S15 and 3-fold in S15 compared to the control. Total leaf water potential (Ψ_w) decreased from an average value of approximately −1.0 MPa, measured on control plants and S10, to −1.17 MPa in S15. In S15, photosynthesis was reduced by 23% and stomatal conductance decreased by 61%. Moreover, salinity induced ABA accumulation both in tomato leaves and roots of the more stressed treatment (S15), where ABA level was higher in roots than in leaves (550 and 312 ng g⁻¹ fresh weight, respectively). Our results suggest that the dynamics of ABA and ion accumulation in tomato leaves significantly affected both growth and gas exchange-related parameters in tomato. In particular, ABA appeared to be involved in the tomato salinity response and could play an important role in dry matter partitioning between roots and shoots of tomato plants subjected to salt stress.     

Development of cesium phosphotungstate salt and chitosan composite membrane for direct methanol fuel cells

A novel composite membrane has been developed by doping cesium phosphotungstate salt (Cs_xH_3−xPW₁₂O₄₀ (0 ≤ x ≤3), Cs_x-PTA) into chitosan (CTS/Cs_x-PTA) for application in direct methanol fuel cells (DMFCs). Uniform distribution of Cs_x-PTA nanoparticles has been achieved in the chitosan matrix. The proton conductivity of the composite membrane is significantly affected by the Cs_x-PTA content in the composite membrane as well as the Cs substitution in PTA. The highest proton conductivity for the CTS/Cs_x-PTA membranes was obtained with x = 2 and Cs₂-PTA content of 5 wt%. The value is 6 × 10⁻³ S cm⁻¹ and 1.75 × 10⁻² S cm⁻¹ at 298 K and 353 K, respectively. The methanol permeability of CTS/Cs₂-PTA membrane is about 5.6 × 10⁻⁷, 90% lower than that of Nafion-212 membrane. The highest selectivity factor (φ) was obtained on CTS/Cs₂-PTA-5 wt% composite membrane, 1.1 × 10⁴/S cm⁻³ s. The present study indicates the promising potential of CTS/Cs_x-PTA composite membrane as alternative proton exchange membranes in direct methanol fuel cells.     

Growth characteristics of Botryococcus braunii 765 under high CO2 concentration in photobioreactor

To understand the potential of cultivating Botryococcus braunii with flue gas (normally containing high CO₂) for biofuel production, growth characteristics of B. braunii 765 with 2-20% CO₂ aeration were investigated. The results showed that the strain could grow well without any obvious inhibition under all tested CO₂ concentrations with an aeration rate of 0.2 vvm, even without any culture pH adjustment (ranged from 6.0 to 8.0). The maximum biomass among all conditions was 2.31 g L⁻¹ on 25th day at 20% CO₂. Hydrocarbon content and algal colony size increased with the increase of CO₂ concentration. A negative correlation between algal biomass and culture total phosphorus was observed (from −0.828 to −0.911, P < 0.01). Additionally, 2% sodium hypochlorite solution was used for photobioreactor sterilization to cultivate B. braunii.     

Cyanobacterial cytochrome cM: Probing its role as electron donor for CuA of cytochrome c oxidase

It is well known that efficient functioning of photosynthetic (PET) and respiratory electron transport (RET) in cyanobacteria requires the presence of either cytochrome c₆ (Cytc₆) or plastocyanin (PC). By contrast, the interaction of an additional redox carrier, cytochrome c_M (Cytc_M), with either PET or RET is still under discussion. Here, we focus on the (putative) role of Cytc_M in cyanobacterial respiration. It is demonstrated that genes encoding the main terminal oxidase (cytochrome c oxidase, COX) and cytochrome c_M are found in all 44 totally or partially sequenced cyanobacteria (except one strain). In order to check whether Cytc_M can act as electron donor to COX, we investigated the intermolecular electron transfer kinetics between Cytc_M and the soluble Cu_A domain (i.e. the donor binding and electron entry site) of subunit II of COX. Both proteins from Synechocystis PCC6803 were expressed heterologously in E. coli. The forward and the reverse electron transfer reactions were studied yielding apparent bimolecular rate constants of (2.4 ± 0.1) × 10⁵ M^− 1 s^− 1 and (9.6 ± 0.4) × 10³ M^− 1 s^− 1 (5 mM phosphate buffer, pH 7, 50 mM KCl). A comparative analysis with Cytc₆ and PC demonstrates that Cytc_M functions as electron donor to Cu_A as efficiently as Cytc₆ but more efficient than PC. Furthermore, we demonstrate the association of Cytc_M with the cytoplasmic and thylakoid membrane fractions by immunobloting and discuss the potential role of Cytc_M as electron donor for COX under stress conditions.     

Correlation between grass carp (Ctenopharyngodon idella) resistance to grass carp reovirus and the genetic insert-deletion polymorphisms in promoter and intron of RIG-I gene

RIG-I (retinoic acid-inducible gene I) is an essential cytosolic pathogen recognition receptor that binds to a variety of viral RNA or DNA to induce type I interferons. In the present study, insert–deletion polymorphisms in promoter and introns of CiRIG-I (Ctenopharyngodon idella RIG-I) were explored, their associations with resistance/susceptibility to grass carp reovirus (GCRV) were analyzed. To this end, genomic sequence of CiRIG-I gene was obtained, and twenty pairs of primers were prepared for the detection of insert–deletion polymorphisms. Five insert–deletion mutations were found, a 2-bp mutation and an 8-bp mutation existed in the promoter and other three sizes in 74 bp, 146 bp and 53 bp were sited in the intron 8. After a challenge experiment, only the genotype and allele of − 740 insert–deletion mutation in the promoter and allele of 6804 insert–deletion mutation were significantly associated with resistance/susceptibility to GCRV among the five mutations (P < 0.05). To further identify this correlation, another independent challenge test was carried out. The result revealed that the cumulative mortality in ins/ins genotype individuals (43.75%) at − 740 insert–deletion mutation was significantly lower than that in ins/del (72.09%) and del/del (74.19%) genotypes (P < 0.05). Linkage disequilibrium and haplotype analysis showed 6610 insert–deletion mutation and 6804 insert–deletion mutation were linkage disequilibrium. The haplotype ins–ins (6610ins–6804ins) was significantly susceptible to GCRV, and ins–del (6610ins–6804del) was significantly resistant to GCRV (P < 0.05). Those could be potential gene markers for the future molecular selection of strains that are resistant to GCRV.     

Linkage of cation binding and folding in human telomeric quadruplex DNA

Formation of DNA quadruplexes requires monovalent cation binding. To characterize the cation binding stoichiometry and linkage between binding and folding, we carried out KCl titrations of Tel22 (d[A(GGGTTA)₃]), a model of the human telomere sequence, using a fluorescent indicator to determine [K⁺]_free and circular dichroism to assess the extent of folding. At [K⁺]_free = 5 mM (sufficient for > 95% folding), the apparent binding stoichiometry is 3K⁺/Tel22; at [K⁺]_free = 20 mM, it increased to 8-10K⁺/Tel22. Thermodynamic analysis shows that at [K⁺]_free = 5 mM, K⁺ binding contributes approximately − 4.9 kcal/mol for folding Tel22. The overall folding free energy is − 2.4 kcal/mol, indicating that there are energetically unfavorable contributions to folding. Thus, quadruplex folding is driven almost entirely by the energy of cation binding with little or no contribution from other weak molecular interactions.     

Chemical composition and rumen degradability of three corn hybrids treated with insecticides against the European corn borer (Ostrinia nubilalis)

This experiment determined the chemical composition, rumen degradability (aNDF in stalks and starch in kernels) and in vitro gas production of kernels from three corn hybrids treated (TT) or not treated (control, CTR) with insecticides against the European corn borer (ECB, Ostrinia nubilalis). Two whole-plant silage hybrids belonging to the FAO rating 600 and 700 maturity class (S600 and S700, respectively) and one selected for grain production (G600, FAO rating 600, Dekalb-Monsanto Agricoltura S.p.A., Lodi, Italy) were sown in two main plots (TT and CTR) of an experimental field. Two subsequent treatments of pyrethroids (25 and 1.2 g/ha of cyfluthrin and deltamethrin, respectively) were applied to the TT plots. The insecticide treatment reduced the number of damaged plants (4.5 broken plants/plot versus 0.3 broken plants/plot, P<0.01) and increased the total grain yield by 11% (13.8 t/ha versus 12.4 t/ha), while hybrids did not differ. ECB larvae which bored into the stalk tunnels modified the chemical composition of stalks and kernels. In stalks, total sugars content (i.e. glucose, fructose, sucrose) was about twice that in TT versus CTR plants (123 g/kg versus 60 g/kg DM, P<0.01), while aNDF content was higher in CTR stalks (765 versus 702 g/kg DM, P<0.01). DM degradability after 48 h of incubation of stalks was higher in TT than in CTR, both in vitro (0.360 versus 0.298, P<0.01) and in situ (0.370 versus 0.298, P<0.05), while there were no differences in aNDF degradability. Kernels from TT plots contained less DM (615 g/kg versus 651 g/kg, P<0.01) and more CP (84 g/kg and 78 g/kg DM, P<0.05) than those from CTR plots, while in situ rumen starch disappearance and in vitro gas production were similar. Corn hybrid selected for yield of grain (G600) differed from S600 and S700 due to a higher (P<0.01) content of aNDF, ADF and lignin(sa) in the stalks, and a higher starch content (696 g/kg versus 674 and 671 g/kg DM, P<0.01) and CP (87 g/kg versus 77 and 76 g/kg DM, P<0.05) in grain. The G600 hybrid produced stalks with a lower (P<0.01) aNDF rumen degradability than the S600 and S700.