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Microbial ureases catalyze the hydrolysis of urea to ammonia, and inhibition of these enzymes in rumen has the potential to improve urea utilization efficiency and reduce urinary nitrogen excretion. Urease activity is catalyzed by a protein complex encoded by a gene cluster, and its accessory proteins (especially UreE and UreG) play important roles in transferring nickel to the active site for urease maturation. In this study, a predominant urease gene cluster (5290 bp) from the ruminal microbial metagenome was identified. Isothermal titration calorimetry (ITC) and analytical ultracentrifugation (AUC) analyses showed that the reaction of identified UreE with UreG was endothermic, and was dominated by a hydrophobic interaction, in which each UreE dimer bound 2 M equivalents of UreG monomer to form a UreE 2 -2UreG complex. Mutagenesis analyses showed that the UreG residues Glu-23, Asp-41, Glu-46, Glu-66, Cys-70, His-72, Asp-78, and Asp-118 were involved in the GTPase activity of UreG. Furthermore, variants of Cys-70 and His-72 involved in CPH motif of UreG, as well as the nearby Glu-66 and Asp-78, not only prevented interactions with UreE, but also prevented nickel binding. These data provide additional information regarding UreG residues that may be targeted for the design of new urease inhibitors. Unlabelled Image • Identification of a predominant urease gene cluster of an uncultured ruminal bacterium • Characteristic interactions of UreE and UreG from a rumen microorganism • Identification of critical residues in UreG [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate steam explosion as a pretreatment to enhance degradation of corn stover by ruminal microbiome. The steam explosion conditions were first optimized, and then the efficacy of steam explosion was evaluated both in vitro and in vivo . Steam explosion altered the physical and chemical structure of corn stover as revealed by scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy, respectively, and increased its cellulose content while decreasing hemicellulose content. Steam-exploded corn stover also increased release of reducing sugars, rate of fermentation, and production of volatile fatty acids (VFAs) in vitro . The steam explosion treatment increased microbial colonization and in situ degradation of cellulose and hemicellulose of corn stover in the rumen of dairy cows. Steam explosion may be a useful pretreatment of corn stover to improve its nutritional value as forage for cattle, or as feedstock for biofuel production. [ABSTRACT FROM AUTHOR]

Due to overgrazing, grasslands in northern China have been severely degraded since 1980s. Grassland biomass and plant populations decreased dramatically. Application of fertilizer is a common technique for pasture management in many countries, however, it has not been widely used on China grasslands. Nitrogen (N) is an important productivity driver in grassland ecosystems, but its transportation, allocation and utilization in temperate desert steppe remained unclear. In this study, a sequential nitrogen addition experiment was conducted on a farm in southwestern Jingtai County, Gansu Province, in the transition zone between Loess Plateau and Tengger Desert. Two different grassland plots with moderate grazing (MG) and heavy grazing (HG) were fenced in 2008. N (NH 4 NO 3 ) was applied at the rate of: 12.25 g N·m −2 , 24.5 g N·m −2 , 36.75 g N·m −2 and 49 g N·m −2 , respectively. To determine the amount and distribution of nitrogen applied to the grassland, the 15 N tracer technique was adopted. The results demonstrated that the recovery rates of 15 N ranged from 3.8% to 11.7% in the plants. The nitrogen recovery amount from both shoots and roots increased significantly ( P < 0.05), while the recovery rate decreased gradually with increasing nitrogen application. The 15 N recovery from shoots under HG was much less than from MG. In one growing season, only 18.2%–8.0% of labeled 15 N was derived from fertilizer, so soil nitrogen is still the main source absorbed and utilized by plants. As much as 50.4%–84.4% labeled 15 N remained in soil, which was evenly distributed throughout 0–20 cm soil layer, and significantly increased with nitrogen application rates. The nitrogen remained in the top soil (0–10 cm) pool was much less than that of 10–20 cm layer ( P < 0.05). The nitrogen loss amounts and rates were significantly different among N treatments, which indicated that there was an increasing trend in N loss with increasing N application rates. Loss/recovery analysis showed that 12.25 g N·m −2 was the recommended application rate. This work is expected to provide the lowest risk/return ratio and produce both economic and environmental benefits for the degraded grassland in Gansu and analogus regions in China. [ABSTRACT FROM AUTHOR]

• Dietary supplementation of isoflavone in cows enhances milk antioxidant capacity. • Milk from cows feeding red clover isoflavone improves antioxidant capacity of mice. • Changing animal diets is a natural and effective strategy for developing functional foods. Red clover (Trifolium pratense) isoflavone was supplemented to dairy cows, and antioxidant capacity of milk was assessed. Treated cows increased the activities of antioxidant enzymes, reduced production of oxidation products, and enhanced the concentrations of vitamin E and vitamin C. Moreover, milk fatty acid profile was positive influenced by 8 g/kg red clover isoflavone, with changes in the lower saturated and higher unsaturated fatty acids. We further demonstrated the efficacy of antioxidant capacity of milk in mice, found that milk from cows feeding red clover isoflavone increased the expressions of antioxidant enzymes, and alleviated lipopolysaccharide (LPS)-stimulated tissue damage of duodenum and jejunum, which was related to upregulated metabolism pathways of carbohydrate, lipid, and amino acid, as well as downregulated inflammatory related pathways. Together, dietary supplementation of red clover isoflavone is an effective way to improve milk antioxidant capacity, providing a natural strategy for developing functional foods. [ABSTRACT FROM AUTHOR]

[Display omitted] • A ratiometric fluorescent probe for TBHQ detection based on NCPDs and AuNCs was first established. • The ratio of fluorescence intensity at 480 nm to 630 nm was monitored as analytical signal response. • The fluorescent color changed from red to orange red to green with the TBHQ concentration. • The method had high selectivity, sensitivity, wide linear range towards TBHQ assay. • The method had great application potential in the field of food safety monitoring and inspection. A novel ratiometric fluorescent probe based on non-conjugated polymer dots (NCPDs) and gold nanocluster (AuNCs) was constructed to determine tert -butylhydroquinone (TBHQ). The probe exhibited dual emission peaks at 480 nm and 630 nm under 370 nm excitation. The fluorescence of AuNCs was quenched by TBHQ due to strong electrostatic interactions, whereas the emission of NCPDs increased. The ratio of fluorescence intensity at 480 nm to 630 nm (F 480 / F 630) was monitored as analytical signal response. The probe have been utilized for the detection of TBHQ with good linear relationship in the range of 0.2 to 60 μg/mL. The limit of detection (LOD) and the limit of quantitation (LOQ) were 0.048 μg/mL and 0.159 μg/L, respectively. Three levels of spiked-in TBHQ concentrations were obtained with recovery rates from 80 % to 102 %. The present study provided an effective ratiometric fluorescence method for selective screening of TBHQ in food samples. [ABSTRACT FROM AUTHOR]

Abstract: Bifunctional Fe3O4@MgSiO3 sub-microspheres with superparamagnetic property and high affinity toward metal ions were successfully synthesized via a solvothermal method using Fe3O4@SiO2 as a self-template, and well characterized by means of TEM, XRD, FT-IR, VSM and N2 adsorption isotherms. The as-prepared Fe3O4@MgSiO3 sub-microspheres were then assessed as the adsorbent for Pb2+ removal in water, and various factors influencing the adsorption of Pb2+ were investigated including pH, equilibrium time and initial metal ion concentration. The results indicated that Fe3O4@MgSiO3 sub-microspheres had a mean diameter of 220nm and high superparamagnetic cores, which endowed them with useful magnetic responsivity. Moreover, the large specific surface was beneficial for their strong affinity toward toxic metal ions. The pseudo-second-order equation could describe well the adsorption kinetics with correlation coefficients greater than 0.999. The maximum adsorption capacity for Pb2+ was calculated to be 242.1mg/g based on Langmuir model. Furthermore, the as-prepared Fe3O4@MgSiO3 showed an acceptable reusability using NaOH or Mg2+ solution as the desorbing agent. All information gives an indication that the as-prepared sub-microspheres show their potential as the adsorbent for highly efficient removal of heavy metal ions in wastewater. [Copyright &y& Elsevier]

Abstract The milk fat globule membrane (MFGM) plays an important role in stabilizing fat in the aqueous phase, and the components of this membrane are involved in multiple biological functions. Here, we investigated changes in the protein composition of the MFGM fraction between raw and heated whole milk using a label free proteomic approach. In total, 612 MFGM-related proteins were identified in all groups. Compared with raw milk, the number of proteins that were not identified in the MFGM fraction was increased from pasteurized milk to ultra-high-temperature milk, whereas the number of milk proteins incorporated into the MFGM fraction was similar among heated groups. The abundances of several milk proteins (β-lactoglobulin and β-casein) were increased in the heated milk groups in a temperature-dependent manner. From our functional analysis, proteins that were not identified in the MFGM fraction of heated milk were mainly associated with multiple biological functions. These findings provided novel insights into the effects of heat procedures on MFGM protein components and their potential physiological functions, thereby yielding data on the appropriate heating procedures to use for raw milk. Graphical abstract Unlabelled Image Highlights • Distinct protein properties were identified in different types of heated whole milk. • Heat caused downregulation of proteins of milk fat globule membranes. • Milk proteins were incorporated into milk fat globule membranes following heating. [ABSTRACT FROM AUTHOR]

Specific pathogen-free ducks are important high-grade laboratory animals, with a key role in research related to poultry biosecurity, production, and breeding. However, the genetic characteristics of experimental duck varieties remain poorly explored. Herein we performed whole-genome resequencing to construct a single nucleotide polymorphism genetic map of the genomes of 3 experimental duck varieties [Jinding ducks (JD), Shaoxing ducks (SX), and Fujian Shanma ducks (SM)] to determine their genetic characteristics and identify selection signatures. Subsequent analyses of population structure and genetic diversity revealed that each duck variety formed a monophyletic group, with SM showing richer genetic diversity than JD and SX. Further, on exploring shared selection signatures, we found 2 overlapping genomic regions on chromosome Z of all experimental ducks, which comprised immune response-related genes (IL7R and IL6ST). Moreover, growth and skeletal development (IGF1R and GDF5), meat quality (FoxO1), and stress resistance (HSP90B1 and Gpx8-b) candidate gene loci were identified in strongly selected signatures specific to JD, SM, and SX, respectively. Our results identified the population genetic basis of experimental ducks at the whole-genome level, providing a framework for future molecular investigations of genetic variations and phenotypic changes. We believe that such studies will eventually contribute to the management of experimental animal resources. [ABSTRACT FROM AUTHOR]

Commercial milk products worldwide come not only from cows, but also from goats, buffaloes, camels, and yaks. Milk from non-bovine animals is important culturally and economically. Pseudomonas spp. are frequently linked to milk spoilage under storage temperatures. The objectives of this study were to identify Pseudomonas spp. isolated from goat, buffalo, camel, and yak milks, and to measure proteolytic activity of Pseudomonas spp. under different storage temperatures. Raw milk samples of goat (n = 50), buffalo (n = 25), camel (n = 25), and yak (n = 25) were collected from 5 provinces in China. Pseudomonas spp. were analyzed by Pseudomonas-specific 16S, universal 16S rRNA, and rpoB gene sequence analyses. Proteolytic activity on milk agar, quantification via the trinitrobenzenesulfonic acid assay at 2°C, 4°C, 7°C, 10°C and 25°C, as well as alkaline peptidase gene (aprX) identification were performed to ascertain the proteolytic activity of these isolates. Pseudomonas spp. were found in 46 samples out of total 125 samples. A total of 67 Pseudomonas spp. were identified. Of Pseudomonas isolates, we obtained extracellular peptidase activity in 7 (10.4%) at 2°C, 17 (25.4%) at 4°C, 24 (35.8%) at 7°C, 39 (58.2%) at 10°C, and 41 (61.2%) at 25°C. The results revealed that a wide diversity of Pseudomonas spp. were present in different non-bovine raw milks, with the ability to produce peptidases at storage temperatures. However, proteolytic activity varied widely among the peptidase-positive isolates. A majority of isolates from yak milk had high proteolytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Triple mode detection of nitrite based on MnO 2 NPs and CQDs were developed. • The ratiometric absorbance of dual wavelength was employed in the spectrophotometry. • A free APP PhotoMetrix was used for smartphone-based colorimetry. • The proposed method performed well in high-salt samples without pretreatment columns. • The proposed method was validated with standard Griess spectrophotometric method. A triple-mode colorimetric and fluorescent sensing scheme based on manganese dioxide nanoparticles (MnO 2 NPs) and carbon quantum dots (CQDs) were developed to determine nitrite. MnO 2 NPs can oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) into a blue oxidation product (TMBox), which is further oxidized into a yellow diimine derivative by nitrite. The ratio of absorbance at 652 nm to 452 nm was monitored as signal response for UV–vis detection mode. A "turn-off" CQDs fluorescence probe was also constructed for fluorescent detection mode. Smartphone tool kit was used to capture the color of sample for smartphone-based measurement. Various analytical performance under different detection modes were obtained and compared. The proposed methods were applied to food samples with satisfactory recoveries (83.3–106 %). The results were validated with AOAC standard spectrophotometric method. The current triple-mode detection were accurate, convenient, low-cost and fast for analyzing nitrite in foods and water samples on-site. [ABSTRACT FROM AUTHOR]

A simple and low cost assay for total iron in various samples based on dispersive liquid-liquid microextraction (DLLME) coupled with digital scanning image analysis was proposed. Orthogonal experiment design was utilized to optimize the amount of extraction solvent and disperser solvent, O-phenanthroline concentration and buffer pH. Under the optimum conditions, the calibration curve was linear over the range of 0.047–1.0 μg mL −1 (R 2 > 0.99) of iron. The limit of detection (LOD) for iron was 14.1 μg L −1 and limit of quantification (LOQ) was 46.5 μg L −1 . The relative standard deviations for seven replicate determinations of 0.5 μg mL −1 of iron was 3.75%. The method was successfully applied for analysis of total iron in water and food samples without using any spectral instrument and it could have a potential industrial impact in developing fast and portable devices to analyze the iron content in water and certain foods. [ABSTRACT FROM AUTHOR]

A novel microvolume UV–vis spectrophotometry method was proposed for the rapid determination of total iron coupling with an efficient pretreatment method known as dispersive liquid–liquid microextraction (DLLME). The basis of the method is a quantitative colorimetric reaction between ferrous iron and 2-(5-bromo-2-pyridylazo)-5-(diethyl amino) phenol (5-Br-PADAP) after the reduction of Fe(III) to Fe(II) by using ascorbic acid as reducing agent. Parameters related to the efficiency of microextraction, such as pH, complexant concentration, the volume ratio of disperser solvent and extraction solvent were discussed and optimized in detail. Under the optimized conditions, the absorbance was in proportion to iron concentration in the range of 5–400 μg L −1 with a correlation coefficient ( R ) of 0.9993. The limit of detection (LOD) and limit of quantitation (LOQ) were 1.5 μg L −1 and 5.2 μg L −1 , respectively. The relative standard deviation (RSD) for samples were 1.37– 4.42% ( n = 3). Good recoveries of iron were obtained in the range of 95.4–103.2% in food samples, 96.9–103.6% in water samples and 98.8–102.3% in Certified Reference Material. The proposed method was rapid, reliable and high-selective for the determination of total iron in food and water samples. [ABSTRACT FROM AUTHOR]

• Changes in whey proteomes depending on the lactation stage and parity identified. • Differences in whey proteome related to the lactation stage and parity revealed. • Heparanase and syntenin may serve as biomarkers of specific lactation stages. • Hemoglobin, β-lactoglobulin, and apolipoprotein E associated with the parity. • Most of the altered proteins involved in response to stimulus and protein metabolic process. Milk yield and several components of milk that are affected by physiological factors have been widely investigated. However, the effects of lactation stage and parity on bovine milk whey proteins have not been well elucidated. To aid in unraveling the proteome profile and exploring the protein biosynthesis of mammary glands, a label-free proteomic approach was used to characterize whey proteomes depending on the lactation stage and parity of dairy cows. The results of this study show that the abundances of several proteins, such as early lactation protein, syntenin, and heparanase, were associated with specific stages of the lactation cycle; this was evidenced by a principal component analysis. In addition, several proteins, such as hemoglobin subunits beta and alpha, β-lactoglobulin, CD320, and apolipoprotein E, corresponded to the parity of the dairy cows and were herein considered as useful biomarkers to distinguish different parities. Most of the differentially expressed proteins from specific lactation stages and parity milk groups were annotated in the response to stimulus and protein metabolic processes. The findings reveal that developmental changes in whey proteomes correspond to lactation stages and parities, which in turn provides new insight into the underlying implications of the production of specific proteins to meet the health benefits of offspring and host, and allow us to explore the mechanisms of protein biosynthesis in mammary glands associated with physiological changes in dairy cows. [ABSTRACT FROM AUTHOR]

Antibiotics are increasingly found in dairy products. To ensure consumer safety, rapid screening methods which are accurate and cost-effective are highly in demand. A multiplexed detection technology was tested for quantification of these four kinds of antibiotics simultaneously in milk. The visual microarray technology based on enzyme-linked immunosorbent assays was utilized in this method, which can detect multiple target molecules simultaneously. This colorimetric technology provides direct results that can be detected using common commercial microplate scanners. The limit of detection (LOD) were calculated as 3.30, 3.39, 2.42 and 4.88 μg kg−1 for quinolones, tetracycline, lincomycin and streptomycin, respectively. The limits of quantity (LOQ) were defined as 8.97, 8.43, 5.36 and 10.97 μg kg−1 for quinolones, tetracycline, lincomycin and streptomycin, respectively. The accuracy of method was also adequate for these four substances with the recovery rates ranging from 77.6% to 116.4% were obtained for the detection of practical samples. According to our evaluation, this methodology can be used for rapid screening of antibiotics in internal quality control programs in dairy industry. • The multiplexed detection method for testing veterinary antibiotics in milk were evaluation. • The ELISA-based visualization microarray chip technique using 96-well microplate. • The limit of detection are less than the MRL established in China, the CAC and the EU. • The accuracy of method was adequate for these four veterinary antibiotics. [ABSTRACT FROM AUTHOR]