Phosphorus desorption and isotope exchange kinetics in agricultural soils

To improve phosphorus (P) fertilization and environmental assessments, a better understanding of release kinetics of solid-phase P to soil solution is needed. In this study, Fe (hydr)oxide-coated filter papers (Fh papers), isotopic exchange kinetics (IEK) and chemical extractions were used to assess the sizes of fast and slowly desorbing P pools in the soils of six long-term Swedish field experiments. The P desorption data from the Fh-paper extraction of soil (20 days of continual P removal) were fitted with the Lookman two-compartment desorption model, which estimates the pools of fast (Q₁) and slowly (Q₂) desorbing P, and their desorption rates k₁ and k₂. The amounts of isotope-exchangeable P (E) were calculated (E_1min to E_{>3 months}) and compared with Q₁ and Q₂. The strongest relationship was found between E_{1 min} and Q₁ (r² = .87, p < .01). There was also an inverse relationship between the IEK parameter n (the rate of exchange) and k₁ (r² = .52, p < .01) and k₂ (r² = .52, p < .01), suggesting that a soil with a high value of n desorbs less P per time unit. The relationships between these results show that they deliver similar information, but both methods are hard to implement in routine analysis. However, Olsen-extractable P was similar in magnitude to Q₁ (P-Olsen = 1.1 × Q₁ + 2.3, r² = .96), n and k₁ were related to P-Olsen/P-CaCl₂, while k₂ was related to P-oxalate/P-Olsen. Therefore, these extractions can be used to estimate the sizes and desorption rates of the different P pools, which could be important for assessments of plant availability and leaching.     

Toll‐like receptor and related cytokine mRNA expression in bovine corpora lutea during the oestrous cycle and pregnancy

Improving our understanding of the mechanisms controlling the corpus luteum (CL) and its role in regulating the reproductive cycle should lead to improvements in the sustainability of today's global animal industry. The corpus luteum (CL) is a transient endocrine organ composed of a heterogeneous mixture steroidogenic, endothelial and immune cells, and it is becoming clear that immune mechanisms play a key role in CL regulation especially in luteolysis. Toll‐like receptors (TLR) mediate innate immune mechanisms via the production of pro‐inflammatory cytokines, especially within various tissues, although the role of TLR within CL remains unknown. Thus, the objectives of this study were to characterize TLR mRNA expression in the CL during the oestrous cycle and in pregnancy (day 30–50), and to examine the role of TLR signalling in luteal cells. Corpora lutea were collected at various stages of the cycle and pregnancy and analysed for TLR and cytokine mRNA expression. In addition, luteal cells were cultured with the TLR4 ligand (lipopolysaccharide, LPS) for 24 h to evaluate the role of TLR4 in regulating luteal function. Toll‐like receptors 1, 2, 4, 6, tumour necrosis factor alpha (TNF), interferon gamma (IFN‐G), and interleukin (IL)‐12, mRNA expressions were greatest in regressing CL compared with earlier stages (p < .05), whereas no change was observed for IL‐6 mRNA expression. Cytokine mRNA expression in cultured luteal cells was not altered by LPS. Based on these data, one or more of the TLRs found within the CL may play a role in luteolysis, perhaps via pro‐inflammatory cytokine mRNA expression.     

In situ observations of a high-pressure phase of H2O Ice

A previously unknown solid phase of H2O has been identified by its peculiar growth patterns, distinct pressure-temperature melting relations, and vibrational Raman spectra. Morphologies of ice crystals and their pressure-temperature melting relations were directly observed in a hydrothermal diamond-anvil cell for H2O bulk densities between 1203 and 1257 kilograms per cubic meter at temperatures between -10 degrees and 50 degreesC. Under these conditions, four different ice forms were observed to melt: two stable phases, ice V and ice VI, and two metastable phases, ice IV and the new ice phase. The Raman spectra and crystal morphology are consistent with a disordered anisotropic structure with some similarities to ice VI.     

Infection of gnotobiotic calves with Escherichia coli o157:h7 strain A84.

Six colostrum-deprived, hysterotomy-derived calves were maintained under sterile conditions and fed a milk replacer diet. At five days of age, five of the calves were dosed orally with 10(9) cfu of Escherichia coli O157:H7 strain A84. They were killed after, one, two, six, 12 and 24 days, and samples were taken for bacteriological and pathological examination. The sixth uninfected control calf was killed at seven days of age and matched samples were taken for pathological comparison. The animals remained normal throughout the observation period. Bacteriological data indicated a heavy bacterial load of strain A84 throughout the gastrointestinal tract but the bacterium was not found in liver, kidney or muscle. No evidence of 'attaching and effacing' lesions in the small or large intestine was found although there was a mild inflammatory response in the intestinal tract, consisting mainly of infiltrating eosinophils.     

Effect of dose and route of administration of thyroid releasing hormone (TRH) on the concentration of prolactin (PRL) and thyroxine (T4) in cyclic gilts

Our objective was to examine the ability of thyroid releasing hormone (TRH) to stimulate not only the release of the thyroid hormones, but also prolactin (PRL) in the female pig. An experiment was conducted to determine the effect of dose and route of administration of TRH on the concentration of PRL and thyroxine (T4) in cyclic gilts. Six gilts were injected with 0, 5, 25, 125, and 625 micrograms TRH and fed 0, 5, 2.5, 12.5 and 62.5 mg TRH. Gilts received TRH once daily. During the 10-day treatment period, route of TRH administration alternated between i.v. injection and feeding. The dose of TRH progressed from the lowest to the highest. Blood samples were taken prior to TRH injection and thereafter at 15-min intervals for 3 hr. Sampling continued for an additional 3 hr at 30-min intervals when TRH was fed. Concentrations of PRL and T4 were determined by radioimmunoassay. Intravenous injection of gilts with 125 and 625 micrograms TRH resulted in an increase in PRL from 0 to 15 min (P less than .05). All doses of TRH given i.v. elevated T4 over a 2-hr period (P less than .01). TRH failed to increase PRL when TRH was fed (P greater than .5). The feeding of 62.5 mg TRH elevated T4 from 0 to 6 hr (P less than .01). Thus, TRH injection increased PRL rapidly and T4 gradually. When TRH was fed, only a gradual elevation in T4 was observed. We conclude that TRH can elicit the release of both PRL and T4 in the cyclic gilt, but magnitude and duration of the PRL and T4 response depends on the dose and route of TRH administration.     

Gradient differences in soil metal solubility and uptake by shoots and roots of wheat (T. aestivum)

The aim of this research was to identify and quantify gaps in currents methods and models for predicting the plant availability of selected nutrient and contaminant metals (Cu, Ni, Zn, Cd) in soil. This study investigated relationships between the relative solubility of Cu, Ni, Zn, and Cd determined by six extraction methods with short-term uptake by shoots and roots of wheat (Triticum aestivum). For Cu, Ni, and Cd, relationships between solubility and plant uptake were found to be different for shoots and roots, with Cu and Ni solubility being more closely correlated with root uptake compared with shoot uptake. Correlation coefficients for Cd concentrations in shoot and root tissue for all six solubility methods were poor (r ²?<?0.5), while corresponding results for Zn explained more than 50 % of shoot variation but less than 50 % of root variation. Soil Cu solubility explained up to 85 % of variation in root uptake compared with 42–55 % for shoot uptake. These results clearly demonstrated that purely chemical and passive diffusion mechanisms were inadequate predictors of Cd uptake by shoots and roots, together with Cu uptake by shoots. Thus further attempts at refining soil metal bioavailability assays based solely on chemical extraction without consideration of plant responses are unlikely to improve prediction of plant uptake.     

The Influence of Maca (<Emphasis Type="Italic">Lepidium meyenii</Emphasis>) on Antioxidant Status,Lipid and Glucose Metabolism in Rat

This work focused on the effect of maca on lipid, anti-oxidative, and glucose parameters in hereditary hypertriglyceridemic (HHTg) rat. Maca (1%) was administred to rats as a part of a high-sucrose diet (HSD) for 2 weeks. Rosiglitazone (0.02%) was used as a positive control. Maca significantly decreased the levels of VLDL (very low density lipoproteins), LDL (low density lipoproteins), and total cholesterol, and also the level of TAG (triacylglycerols) in the plasma, VLDL, and liver. Maca, as well as rosiglitazone, significantly improved glucose tolerance, as the decrease of AUC (area under the curve) of glucose showed, and lowered levels of glucose in blood. The activity of SOD (superoxide dismutase) in the liver, the GPX (glutathione peroxidase) in the blood, and the level of GSH (glutathione) in liver increased in all cases significantly. Results demonstrate that maca seems to be promising for a positive influence on chronic human diseases (characterized by atherogenous lipoprotein profile, aggravated antioxidative status, and impaired glucose tolerance), and their prevention.     

Development of single-dispenser pheromone suppression of Epiphyas postvittana, Planotortrix octo and Ctenopseustis obliquana in New Zealand stone fruit orchards

BACKGROUND: Pheromones of two native leafrollers of economic importance to the New Zealand horticulture industry, Planotortrix octo [(Z)‐8‐tetradecenyl acetate and tetradecyl acetate] and Ctenopseustis obliquana [(Z)‐5‐tetradecenyl acetate and (Z)‐8‐tetradecenyl acetate], were reinvestigated and combined with pheromone of Epiphyas postvittana [light‐brown apple moth, (E)‐11‐tetradecenyl actetate and (E, E)‐9,11‐tetradecen‐1‐yl acetate] to develop a single dispenser for mating disruption of three pest species for integrated pest management. RESULTS: Additional compounds identified from pheromone gland extracts were characterised as repellents for P. octo. However, for C. obliquana from Central Otago, a change in ratio of (Z)‐5‐tetradecenyl acetate and (Z)‐8‐tetradecenyl acetate and the addition of three compounds found in the gland (dodecyl acetate, tetradecyl acetate and hexadecanal) led to a significant improvement in catch over previous lures. Males from Central Otago showed antennal electrophysiological responses to hexadecanal, unlike C. obliquana from Auckland, which did not. Three multiple‐species disruption blends were devised in a single dispenser to target E. postvittana, P. octo and C. obliquana. Disruption of traps was recorded in single‐tree replicates with all three blends, but the five‐component blend was overall most effective at disruption and was deployed area wide in commercial orchard plots. CONCLUSIONS: Deployment of single dispensers into commercial stone fruit orchards led to disruption of trapping for the three species and measurable reductions in insecticide use in cherries, peaches and nectarines without increased fruit damage (assessed in apricots). Copyright © 2011 Society of Chemical Industry