Influence of protein concentration on the sulphur‐containing amino acid requirement of broiler chickens 1

1. Two experiments were conducted with male broiler chickens from 3 to 6 weeks of age to determine the effect of dietary protein content on the requirement for sulphur amino acids (SAA). In experiment 1, 0, 0.5, 1.0 or 1.5 g DL‐methionine/kg were added to diets calculated to contain 200, 240 or 280 g protein/kg. In experiment 2, 0, 0.6, 1.2 or 1.8 g DL‐methionine/kg were added to diets calculated to contain 160, 180 or 200 g protein/kg.

2. In experiment 1, the SAA requirement for body weight gain increased as dietary protein content increased. Regression analysis indicated a requirement of 38 g SAA/kg protein.

3. In experiment 2 in which lysine supplementation provided a minimum of 10 g/kg, the requirement for SAA per unit of diet increased only slightly as protein concentration increased indicating that below 200 g protein/kg of diet, the SAA requirement increases per unit of protein with supplementation of the second‐limiting amino acid.

4. Abdominal fat percentage declined in a linear manner with each increment of SAA added to diets containing 160 to 200 g protein/kg. Adding methionine to diets containing 240 or 280 g protein/kg did not affect abdominal fat content. A lower limit of abdominal fat was achieved with a protein concentration of 240 g/kg.

5. It is concluded that the requirement for SAA of finishing broiler chickens is directly related to protein content at concentrations of 200 or more g protein/kg but increases per unit of protein at lower protein concentrations when a minimum lysine concentration is specified. Abdominal fat content reaches a minimum between 200 and 240 g protein/kg of a maize‐soyabean meal diet regardless of SAA content.     

Factors affecting the transfer of immunoglobulin G1 into the milk of Holstein cows

Immunoglobulin (Ig) G1 concentrations in milk from Holstein cows was measured to determine if transfer and concentration was influenced by production factors (lactation number, stage of lactation, daily milk production), milk composition (milk fat, protein, lactose, and total solids content) or by serum IgG1 concentration. Two hundred and ninety-nine Chinese Holstein cows were randomly selected from four herds containing a total of more than 1600 lactating animals. The concentration of IgG1 in the milk and serum was determined by ELISA.Milk IgG1 concentrations varied between 0.030 and 0.614 mg/mL and significantly correlated with lactation number, stage of lactation, daily milk production and somatic cell count. The IgG1 mass was found to highly correlate with lactation number, stage of lactation, daily milk production and milk protein content. Lactation number had the highest positive direct relationship with IgG1 concentration.     

Determination of cinnamyl anthranilate in perfume, cologne, and toilet water by liquid chromatography with fluorescence detection

A liquid chromatographic method with fluorescence detection was developed for the determination of cinnamyl anthranilate in perfumes and other fragrance compositions. The method was evaluated by conducting recovery studies of 10 different commercial fragrance compositions to which cinnamyl anthranilate had been added at levels of 0.1, 0.5, and 1.0 mg/mL. Recoveries ranged from 91 to 103% with a mean of 97% and a standard deviation of +/- 3.3%.     

Protein conformational dynamics probed by single-molecule electron transfer

Electron transfer is used as a probe for angstrom-scale structural changes in single protein molecules. In a flavin reductase, the fluorescence of flavin is quenched by a nearby tyrosine residue by means of photo-induced electron transfer. By probing the fluorescence lifetime of the single flavin on a photon-by-photon basis, we were able to observe the variation of flavin-tyrosine distance over time. We could then determine the potential of mean force between the flavin and the tyrosine, and a correlation analysis revealed conformational fluctuation at multiple time scales spanning from hundreds of microseconds to seconds. This phenomenon suggests the existence of multiple interconverting conformers related to the fluctuating catalytic reactivity.     

Effects of initial epidemic conditions, sporulation rate, and spore dispersal gradient on the spatio-temporal dynamics of plant disease epidemics

ABSTRACT A stochastic model that simulates the spread of disease over space and time was developed to study the effects of initial epidemic conditions (number of initial inocula and their spatial pattern), sporulation rate, and spore dispersal gradient on the spatio-temporal dynamics of plant disease epidemics. The spatial spread of disease was simulated using a half-Cauchy distribution with median dispersal distance mu (units of distance). The rate of temporal increase in disease incidence (beta(I), per day) was influenced jointly by mu and by the sporulation rate lambda (spores per lesion per day). The relationship between beta(I) and mu was nonlinear: the increase in beta(I) with increasing mu was greatest when mu was small (i.e., when the dispersal gradient was steep). The rate of temporal increase in disease severity of diseased plants (beta(S)) was affected mainly by lambda: beta(S) increased directly with increasing lambda. Intraclass correlation (kappa(t)), the correlation of disease status of plants within quadrats, increased initially with disease incidence, reached a peak, and then declined as disease incidence approached 1.0. This relationship was well described by a power-law model that is consistent with the binary form of the variance power law. The amplitude of the model relating kappa(t) to disease incidence was affected mainly by mu: kappa(t) decreased with increasing mu. The shape of the curve was affected mainly by initial conditions, especially the spatial pattern of the initial inocula. Generally, the relationship of spatial autocorrelation (rho(t,k)), the correlation of disease status of plants at various distances apart, to disease incidence and distance was well described by a four-parameter power-law model. rho(t,k) increased with disease incidence to a maximum and then declined at higher values of disease incidence, in agreement with a power-law relationship. The amplitude of rho(t,k) was determined mainly by initial conditions and by mu: rho(t,k) decreased with increasing mu and was lower for regular patterns of initial inocula. The shape of the rho(t,k) curve was affected mainly by initial conditions, especially the spatial pattern of the initial inocula. At any level of disease incidence, autocorrelation declined exponentially with spatial lag; the degree of this decline was determined mainly by mu: it was steeper with decreasing mu.     

Correlation of the highest-energy cosmic rays with nearby extragalactic objects

Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 x 10(19) electron volts and the positions of active galactic nuclei (AGN) lying within approximately 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest-energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.     

Combined effect of biochar and soil moisture on soil chemical properties and microbial community composition in microplastic-contaminated agricultural soil

Accumulation of microplastics (MPs) in agricultural environments has caused growing concern in recent years because of its detrimental impacts on soil quality, crop productivity and ecosystem function. This study was conducted to assess the impact of biochar on soil chemical and microbial properties in a MP-contaminated soil under two moisture regimes. Soil was contaminated with 1% (w/w) of low-density polyethylene MPs. Four types of standard biochar, that is, oil seed rape (OSR) biochar produced at 550°C (OSR 550) and 700°C (OSR 700) and soft wood pellet (SWP) biochar produced at 550°C (SWP 550) and 700°C (SWP 700), were applied at a rate of 5% (w/w). The control was maintained without MP addition. The samples were incubated in soil with two moisture regimes, that is, at 30% and 70% of the water holding capacity, and the soil chemical and microbiological properties were assessed after 100 days of incubation. OSR biochar application significantly increased soil pH (8.53–8.81) and electrical conductivity (0.51–0.58 dS/m) in both moisture regimes. The effect of biochar application on soil enzyme activity and microbial community composition did not show a clear trend. However, SWP 700 biochar improved soil enzyme activity compared with that of the control and improved bacterial diversity and evenness compared with those of other biochars, which was attributed to the high surface area available for microbial colonization. Low soil moisture content significantly reduced enzyme activity and bacterial richness even with biochar amendment, except for SWP 550 biochar. This study implies the suitability of biochar for improvement of soil quality in MP contaminated soil under both moisture regimes. However, further long-term studies are needed to get a clear understanding on the impact of different types of biochar on MP-contaminated soil.     

Effect of temperature regime on germination of seed of perennial ryegrass (Lolium perenne)

Perennial ryegrass ( Lolium perenne L.) is one of the most valuable temperate pasture grasses in the world. Understanding seed germination in response to temperature can help determine its optimal seeding times. Germination tests for two cultivars of perennial ryegrass (cv. 'Turfstar' and cv. 'Transtar') were conducted by applying thirty-six constant and alternating temperature regimes, ranging from 5 to 40°C (16 h night/8 h day). Responses in germination rate to these temperature regimes were then used to construct a quadratic response surface, giving estimated germination rates with confidence intervals at P  ≤   0·05 for both cultivars. Optimum germination rate occurred over a range of regimes: 15/25, 20/25, 20/30 and 25/30°C. Furthermore, a wide range in diurnal alternating temperatures resulted in maximum seed germination rate for cv. 'Transtar', while no constant temperature regime supported maximum germination rate for cv. 'Turfstar'. A temperature-dependent germination rate function for perennial ryegrass was developed which could be used in the future to predict location-specific optimum seeding times when national or regional monthly temperature data are available.     

Requirement of CHROMOMETHYLASE3 for maintenance of CpXpG methylation

Epigenetic silenced alleles of the Arabidopsis SUPERMAN locus (the clark kent alleles) are associated with dense hypermethylation at noncanonical cytosines (CpXpG and asymmetric sites, where X = A, T, C, or G). A genetic screen for suppressors of a hypermethylated clark kent mutant identified nine loss-of-function alleles of CHROMOMETHYLASE3 (CMT3), a novel cytosine methyltransferase homolog. These cmt3 mutants display a wild-type morphology but exhibit decreased CpXpG methylation of the SUP gene and of other sequences throughout the genome. They also show reactivated expression of endogenous retrotransposon sequences. These results show that a non-CpG DNA methyltransferase is responsible for maintaining epigenetic gene silencing.     

Effects of phenylalanine and threonine oligopeptides on milk protein synthesis in cultured bovine mammary epithelial cells

This study was conducted to investigate the effects of phenylalanine (Phe) and threonine (Thr) oligopeptides on α_s1 casein gene expression and milk protein synthesis in bovine mammary epithelial cells. Primary mammary epithelial cells were obtained from Holstein dairy cows and incubated in Dulbecco's modified Eagle's medium‐F12 medium (DMEM/F12) containing lactogenic hormones (prolactin and glucocorticoids). Free Phe (117 μg/ml) was substituted partly with peptide‐bound Phe (phenylalanylphenylalanine, phenylalanyl threonine, threonyl‐phenylalanyl‐phenylalanine) in the experimental media. After incubation with experimental medium, cells were collected for gene expression analysis and medium was collected for milk protein or amino acid determination. The results showed that peptide‐bound Phe at 10% (11.7 μg/ml) significantly enhanced α_s1 casein gene expression and milk protein synthesis as compared with equivalent amount of free Phe. When 10% Phe was replaced by phenylalanylphenylalanine, the disappearance of most essential amino acids increased significantly, and gene expression of peptide transporter 2 and some amino acid transporters was significantly enhanced. These results indicate that the Phe and Thr oligopeptides are important for milk protein synthesis, and peptide‐bound amino acids could be utilised more efficiently in milk protein synthesis than the equivalent amount of free amino acids.