Adsorption of Cadmium and Zinc onto Micaceous Minerals: Effect of Siderophore Desferrioxamine B

The mobility, bioavailability, and environmental fate of heavy metals in soil are controlled by their adsorption onto soil minerals and solid organic matter. The adsorption is strongly affected by the presence of various low-molecular-weight organic acids. In this study, effect of hydroxamate siderophore desferrioxamine B (DFOB) on cadmium (Cd) and zinc (Zn) adsorption onto two micaceous clay minerals, muscovite and phlogopite, was evaluated in batch experiments. Results showed that the presence of DFOB diminished the adsorption of Cd and Zn onto both minerals, particularly under neutral to alkaline pH conditions. For instance, at pH 8.2, the presence of DFOB caused a decrease in the adsorption of Zn onto phlogopite by nearly 50%. The equilibrium adsorption of Cd and Zn was satisfactorily described using Freundlich isotherm. The adsorption isotherms showed that the affinity of Cd and Zn onto the minerals decreased in the presence of DFOB. For example, at pH 8.0, the presence of siderophore caused a decrease in the Freundlich adsorption isotherm coefficient K_F for Zn adsorption onto muscovite and phlogopite from 4.60 to 0.07 L g^-1 and from 3.56 to 0.36 L g^-1, respectively. These findings confirm the potential influence of siderophore on the fate of Cd and Zn in arid soils containing substantial contributions of micaceous silicate minerals.     

Effects of electron beam irradiation on dry matter degradation of wheat straw in the rumen

The effect of electron beam irradiation at doses of 100, 200 and 300 kGy on ruminal dry matter degradation kinetics of wheat straw was investigated. Samples were irradiated by electron beam irradiator under identical conditions of temperature and humidity. Nylon bags of untreated or irradiated wheat straw were suspended in the rumen of three Taleshi steers for up to 96 h and resulting data were fitted to non-linear degradation model to calculate degradation parameters of dry matter. Results show that the washout fractions of dry matter increased linearly (p<0.001), but potentially degradable fraction and degradation rate decreased linearly (p<0.001) by electron beam irradiation. As a consequence, the effective degradability of dry matter increased linearly (p<0.001) with increasing irradiation dose. Electron beam irradiation at doses of 100, 200 and 300 kGy increased the effective degradability of dry matter at rumen outflow rate of 0.05/h by about 7, 15 and 18%, respectively. In the condition of this study, electron beam irradiation at dose of 200 kGy appeared to be a suitable dose for improving dry matter degradability of wheat straw in the rumen.     

Antioxidant properties of peel and pulp hydro extract in ten Persian pomegranate cultivars

This study compares the antioxidant activity of ten different pomegranate cultivars grown in Iran using the ferric reducing power assay (FRAP assay), which is based on the reduction of a ferric-tripyridyl triazine complex to its ferrous, colored form in the presence of antioxidants. Aqueous solutions of known Fe(+2) concentration, in the range of 100-1000 micromol L(-1) were used for calibration. The results showed that among pulp and peel fractions the sour alac and sweet white peel cultivars had more FRAP value respectively. The pomegranate peel extract had markedly higher antioxidant capacity than the pulp extract. The peel extract of sweet white peel cultivar appeared to have more potential as a health supplement rich in natural antioxidants compared to the pulp and peel extracts of other pomegranate cultivars.     

Tolerance of Strawberry Cultivars to Terbacil

Field experiments were conducted to evaluate the tolerance of strawberry cultivars to terbacil. Treatments (84, 168, and 336 g ha^–1) were applied at either dormant stage or 3–4 leaf. Initial crop injury at 1 and 3 weeks after treatment (WAT) ranged between 0% and 43%; all cultivars fully recovered at 6 WAT. Terbacil applied at 168 g ha^–1 at dormant stage caused approximately 20% yield reduction in ‘Brunswick’, ‘Darselect’, and ‘Honeoye’, which was not observed with other treatments. A negative impact of the herbicide on yield of these cultivars is an unlikely outcome when sprayed at 3–4 leaf stage.     

Effects of seasonal variation,group size and sex on the activity budget and diet composition of the addax antelope

Behaviour and diet composition are critical elements in conservation biology within the scope of reintroduction programs. Here we focused on addax (Addax nasomaculatus), a Critically Endangered antelope species, in the Jbil National Park, Tunisia. In this study, we advanced the hypothesis that season, day period, sex and social structure have an effect on the activity budgets and diet composition of addax. Three groups were selected (large group, adult pair and solitary male). Resting, moving, grazing, vigilance and other behaviours were recorded during two seasons (dry and wet) and in the morning and the afternoon. In addition, faecal samples were collected. The results indicate that season and day period were the main factors affecting the activity budgets. The resting behaviour increased from the wet to the dry season, and from morning to afternoon. The grazing and moving behaviours increased during the wet season and decreased from morning to afternoon. Addax select a mixed diet composed of perennial and herbaceous plant species notably during the wet season. In addition, we observed that addax modify their behaviour according to the season and forage availability. This represents an adaptive strategy to survive in a desert climate with a stochastic low-resource environment and depending on ambient climatic conditions.     

Dietary but not in ovo feeding of Silybum marianum extract resulted in an improvement in performance,immunity and carcass characteristics and decreased the adverse effects of high temperatures in broilers

1. A total of 360 fertile eggs from a broiler breeder strain (Ross 308) were used for in ovo feeding (IOF) of 0, 100 and 200 mg/kg Silybum marianum water extract at 17.5 d of incubation.

2. After hatching, 240 chicks were transferred to the experimental cages. The diets consisted of two types; one of them without extract and the other one containing 100 mg/kg of Silybum marianum extract. Then chicks were exposed to elevated temperatures 4°C above optimum from 7 to 28 d of age for 4 h per d and after 28 d they were kept at optimum temperature. The chicks were divided into 6 treatments with 4 replicates as a completely randomised 2 × 3 factorial design.

3. There was no effect of IOF of Silybum marianum extract on hatchability, body weight (BW) of hatched chicks or hatched chick BW/initial egg weight ratio. Chickens fed on the diet containing the extract had the highest feed intake, daily weight gains (DWGs), final BW and lowest feed conversion ratio.

4. At 28 d, the weights of heart, spleen and bursa of birds in the treatment groups given extract were higher, but abdominal fat weights were lower. At 42 d in those fed extract in the diet, the weights of spleen and bursa were higher and abdominal fat weights were lower than the other groups.

5. No differences were observed between groups in body temperature before application of the higher temperature but at 21 d and 28 d the body temperature of chicks given the Silybum marianum extract was lower than the other treatments during the elevated temperatures.

6. In birds fed on the extract in the diet, HDL and cholesterol concentrations were lowest at 28 d, whereas blood glucose levels were higher in the other treatments. At 42 d the cholesterol concentration was significantly lower in birds given extract in their diet.

7. These results indicated that dietary feeding of Silybum marianum extract resulted in an improvement in performance, immunity and carcass characteristics and decreased the adverse effects of the higher temperatures, specifically in reducing blood fat reduction, but IOF of the extract did not have an effect.

     

Comparison of distribution of virulence determinants in clinical and environmental isolates of Vibrio cholera

Background: The virulence of a pathogenic Vibrio cholerae is dependent on a discrete set of genetic determinants. In this study, we determined the distribution of virulence determinants among the clinical and environmental isolates of V. cholerae. Methods: The antibiotic resistance profiles of the isolates were determined using standard disk diffusion assay. PCR assay was performed to analyze the presence of toxin genes of ctx, zot and ace. The composition of cholera toxin encoding element (CTX) region flanking of the V. cholerae isolates was also analyzed. Results: All of the clinical isolates (100%) showed a complete set of virulence genes and also the attachment site of the filamentous bacteriophage CTXphi. None of the environmental isolates contained the virulence genes and the attachment site of the CTXphi. Analysis of the flanking regions including the toxin-linked cryptic element and repeat in toxin genes revealed their integrity in the clinical isolates while in the environmental isolates they were absent or contained incomplete sequences. Comparison of the antibiotic resistance assay of the environmental and clinical isolates showed a significant difference in the resistance profiles of the isolates obtained from the two sites. High rates of resistance to co-trimoxosol, streptomycin and chloramphenicol were found with clinical isolates. Conclusion: The absence of all virulence determinants in the environmental strains may suggest that certain ecological features must be present for V. cholerae to acquire a complete set of virulence determinants and to turn them into pathogenic strains.     

Metal Extractability in Binary and Multi-metals Spiked Calcareous Soils

In the present study, a laboratory experiment was designed to compare the 0.01 M calcium chloride (CaCl₂) and diethylenetriaminepentaacetic acid (DTPA) extraction methods for their ability to predict cadmium (Cd), copper (Cu), iron (Fe), Manganese (Mn), nickel (Ni), and zinc (Zn) availability and mobility in five calcareous soils. The soils were spiked with different amounts of metals (0, 50, 100, 200, and 400 mg kg^?1) both in binary (Cu and Zn; Ni and Cd; Fe and Mn) and in multi-systems (Cd, Cu, Fe, Mn, Ni, and Zn) and incubated for 1 months at field capacity. In metal-spiked soils, both extraction methods showed a linear relationship of extractable to total metals for all soils. The fraction of total metals extracted by DTPA was much higher than the fraction extracted by CaCl₂, which was attributed to the formation of soluble metal-complexes in the complexing extracts calculated by the Visual Minteq program. DTPA extraction method showed higher selectivity for Cu over other metals both in binary and in multi-systems. Different order of metals extractability was found in binary and multi-systems for both extraction methods. Solid/solution distribution coefficient (K_d) was calculated by the ratio of the solid phase to soil solution concentration of metals extracted by CaCl₂ or DTPA extraction methods. Both in binary and in multi-systems, the average K_d (l kg^?1) of metals by soils were in the order of Mn (5398) > Fe (4413) > Zn (3376) > Cu (2520) > Ni (969) > Cd (350) in the CaCl₂-extractable metals and Fe (35) ≥ Ni (34) > Zn (18) > Mn (11.2) > Cu (6.3) > Cd (4) in the DTPA-extractable metals. Results showed that among the six studied metals, Cd had the lowest K_d, implying a relative higher mobility in these calcareous soils. The Visual Minteq indicated that in the CaCl₂-extraction method and in both binary and multi-systems the dominant species for Cu, Mn, Ni, and Zn were Cu²⁺, Mn²⁺, Ni²⁺ and Zn²⁺, respectively, while for Cd and Fe, the dominant species were CdCl⁺ and Fe(OH)²⁺, respectively.     

Adjusted friction correction factors for center-pivots with an end-gun

A new method for calculating total friction head loss in center-pivots with an operational end-gun was developed. The proposed methodology is based on adjusting the previous friction correction factors for center-pivots with end-guns in order to correct their paradoxes and shortcomings. Equations presented in the current work are developed for center-pivots with a finite number of outlets along the lateral and constant outlet spacing and discharge as well as constant discharge and variable spacing. The proposed formulas depend on the number of outlets along the supply pipeline, the exponent of velocity term in the friction formula used and the distance that water is jetted by the end-gun. All equations reduce to the well-established equations for the friction correction factor when the end-gun is turned off. The equations presented here compare well to the stepwise friction calculation method, yet correct slight errors in the way that these friction correction factors were calculated in the past.