Herd-level risk factors associated with the presence of Phage type 21/28 E. coli O157 on Scottish cattle farms

Background  

E. coli O157 is a bacterial pathogen that is shed by cattle and can cause severe disease in humans. Phage type (PT) 21/28 is a subtype of E. coli O157 that is found across Scotland and is associated with particularly severe human morbidity.     

Abscisic acid triggers whole-plant and fruit-specific mechanisms to increase fruit calcium uptake and prevent blossom end rot development in tomato fruit

Calcium (Ca) uptake into fruit and leaves is dependent on xylemic water movement, and hence presumably driven by transpiration and growth. High leaf transpiration is thought to restrict Ca movement to low-transpiring tomato fruit, which may increase fruit susceptibility to the Ca-deficiency disorder, blossom end rot (BER). The objective of this study was to analyse the effect of reduced leaf transpiration in abscisic acid (ABA)-treated plants on fruit and leaf Ca uptake and BER development. Tomato cultivars Ace 55 (Vf) and AB2 were grown in a greenhouse environment under Ca-deficit conditions and plants were treated weekly after pollination with water (control) or 500 mg l(-1) ABA. BER incidence was completely prevented in the ABA-treated plants and reached values of 30-45% in the water-treated controls. ABA-treated plants had higher stem water potential, lower leaf stomatal conductance, and lower whole-plant water loss than water-treated plants. ABA treatment increased total tissue and apoplastic water-soluble Ca concentrations in the fruit, and decreased Ca concentrations in leaves. In ABA-treated plants, fruit had a higher number of Safranin-O-stained xylem vessels at early stages of growth and development. ABA treatment reduced the phloem/xylem ratio of fruit sap uptake. The results indicate that ABA prevents BER development by increasing fruit Ca uptake, possibly by a combination of whole-plant and fruit-specific mechanisms.     

Metabolic response of Platynota stultana pupae during and after extended exposure to elevated CO(2) and reduced O(2) atmospheres

The metabolic response of Platynota stultana pupae to elevated CO(2) and reduced O(2) atmospheres was measured using microcalorimetry. Initial measurements at 20 degrees C immediately upon placement in controlled atmosphere indicated a decrease in metabolic heat rate (MHR) of 27, 45, 56, 56, and 72% in an atmosphere of 5, 10, 20, 40, and 79% CO(2), respectively, and a decrease of 20, 50, 66 and 100% under 6, 2, 1, and 0% O(2). With extended exposure to controlled atmospheres, MHR increased under 5, 10, and 20% CO(2) and 6 and 2% O(2); however, the increase was greater and occurred more rapidly with lower CO(2) and higher O(2) concentration. The MHR at 40 and 79% CO(2) remained at the initial reduced level for 8 and 6 days, respectively, then decreased with longer exposure. The MHR of pupae held under 1 and 0% O(2) remained at the initial reduced level for 22 days. Upon transfer to air, the MHR of pupae increased from the reduced levels and then decreased. When the MHR decreased by no more than 30%, as a result of controlled atmosphere treatment, the pupae still developed into adults. However, when the MHR decreased by more than 50%, the energy supply was insufficient and the pupae died. Pupa mortality was comparable between 5% CO(2) and 6% O(2), and 10% CO(2) and 2% O(2). The MHR was reduced less under 20% CO(2) than under 2 or 1% O(2); however, the pupae were more susceptible to 20% CO(2) than 2 or 1% O(2). These and other data indicate an increased toxicity of high CO(2) over low O(2) atmospheres that may be related to an increase in membrane permeability as a result of CO(2) treatment.     

Tomato Fruit Cell Wall Synthesis during Development and Senescence : In Vivo Radiolabeling of Wall Fractions Using [C]Sucrose

The pedicel of tomato fruit (Lycopersicon esculentum Mill., cv `Rutgers') of different developmental stages from immature-green (IG) to red was injected on the vine with 7 microcuries [¹⁴C(U)]sucrose and harvested after 18 hours. Cell walls were isolated from outer pericarp and further fractionated yielding ionically associated pectin, covalently bound pectin, hemicellulosic fraction I, hemicellulosic fraction II, and cellulosic fraction II. The dry weight of the total cell wall and of each cell wall fraction per gram fresh weight of pericarp tissue decreased after the mature-green (MG) stage of development. Incorporation of radiolabeled sugars into each fraction decreased from the IG to MG3 (locules jellied but still green) stage. Incorporation in all fractions increased from MG3 to breaker and turning (T) and then decreased from T to red. Data indicate that cell wall synthesis continues throughout ripening and increases transiently from MG4 (locules jellied and yellow to pink in color) to T, corresponding to the peak in respiration and ethylene synthesis during the climacteric. Synthesis continued at a time when total cell wall fraction dry weight decreased indicating the occurrence of cell wall turnover. Synthesis and insertion of a modified polymer with removal of other polymers may produce a less rigid cell wall and allow softening of the tissue integrity during ripening.     

Effects of sodium and magnesium sulfate in drinking water on mallard ducklings

One-day-old mallard (Anas platyrhynchos) ducklings were given drinking water for up to 28 days that contained concentrations of sodium and/or magnesium similar to those found in saline wetlands. Growth, tissue development, and biochemical characteristics of these ducklings were compared to those reared on fresh water. Much of the ingested salt was excreted by passage of voluminous fluid excreta. This effect occurred in birds given water with as little as 500 ppm Mg or 1,000 ppm Na. The supraorbital salt gland was active within 4 days in ducklings drinking water containing greater than or equal to 1,500 ppm of Na. Feather growth was decreased in ducklings drinking water with greater than or equal to 1,500 ppm of either Na or Mg. Ducklings drinking water with 3,000 ppm of either ion, or 1,500 ppm of each, grew more slowly than control birds. Ducklings drinking water with 3,000 ppm of either Na or Mg had reduced thymus size and bone breaking strength. Those drinking water with 3,000 ppm of Mg, or 3,100 ppm Na and 1,300 ppm Mg also had less trabecular bone and enlarged adrenals. Birds drinking the latter water had an elevated concentration of Na and calcium, and a decreased concentration of phosphorus and chloride in their serum, and elevated plasma protein levels. Ducklings reared on fresh or slightly saline water adapted very poorly to an abrupt change to more saline water (specific conductivity = 15,250 microns hos/cm) at 14 days of age. These birds stopped eating, became inactive and some died within 3 days; survivors had many tissue and biochemical abnormalities at 20 days of age. The level of salinity in these trials was similar to that in "brackish" or "moderately saline" wetlands and lower than that previously found to have effects on growth and feathering of ducklings. Many of the sublethal effects were subtle and non-specific manifestations of stress, and would be difficult to detect in wild ducklings on saline wetlands.     

Waist Circumference as a Screening Tool for Cardiovascular Risk Factors: Evaluation of Receiver Operating Characteristics (ROC)

To evaluate the receiver operating characteristics (ROC) to determine the cutoffs of waist circumference as a potential population directed screening tool for hypercholesterolaemia (≥6.5 mmol/L), low high density lipoprotein cholesterol (<0.9 mmol/L), and hypertension (treated and/or systolic ≥160 and/or diastolic blood pressure ≥95 mmHg), in 2183 men and 2698 women aged 20 to 59 years selected at random from Dutch civil registries. Main outcome measures: Height, weight, body mass index (BMI), waist circumference, total plasma cholesterol and high density lipoprotein cholesterol concentrations, and blood pressure. Results: ROC curves showed that sensitivity equalled specificity at waist circumferences between 93–95 cm in men and 81–84 cm in women for identifying individual risk factors, and 92 cm in men and 81 cm in women for identifying those with at least one risk factor. Sensitivity and specificity were equal at levels between 61% to 69% for identifying individual risk factors, with positive predictions (56.8% in men and 37.8% in women) within 2% of those using previously defined ‘Action Level 1’ of waist circumference 94 cm in men and 80 cm in women (58.8% in men and 37.4% in women). Risk prediction by anthropometric methods was relatively low: ROC areas for identifying each risk factor by waist varied from 55% to 60%, and reached about 65% for identifying at least one risk factor. Height accounted for less than 03% of variance in waist circumference. Using BMI at 25 kg/m² gave similar prediction to waist, but its combination with waist did not improve predictive values. Conclusions: Measurement of waist circumference ‘Action Level 1’ at 94 cm (37 inches) in men and 80 cm (32 inches) in women could be adopted as a simpler valid alternative to BMI for health promotion, to alert those at risk of cardiovascular disease, and as a guide to risk avoidance by self-weight management     

Peatland vascular plant functional types affect dissolved organic matter chemistry

Aims

The readily available global rock phosphate (P) reserves may be depleted within the next 50–130 years warranting careful use of this finite resource. We develop a model that allows us to assess a range of P fertiliser and soil management strategies for Barley in order to find which one maximises plant P uptake under certain climate conditions.

Methods

Our model describes the development of the P and water profiles within the soil. Current cultivation techniques such as ploughing and reduced till gradient are simulated along with fertiliser options to feed the top soil or the soil right below the seed.

Results

Our model was able to fit data from two barley field trials, achieving a good fit at early growth stages but a poor fit at late growth stages, where the model underestimated plant P uptake. A well-mixed soil (inverted and 25 cm ploughing) is important for optimal plant P uptake and provides the best environment for the root system.

Conclusions

The model is sensitive to the initial state of P and its distribution within the soil profile; experimental parameters which are sparsely measured. The combination of modelling and experimental data provides useful agricultural predictions for site specific locations.