Treatment of murine colitis by Lactococcus lactis secreting interleukin-10

The cytokine interleukin-10 (IL-10) has shown promise in clinical trials for treatment of inflammatory bowel disease (IBD). Using two mouse models, we show that the therapeutic dose of IL-10 can be reduced by localized delivery of a bacterium genetically engineered to secrete the cytokine. Intragastric administration of IL-10-secreting Lactococcus lactis caused a 50% reduction in colitis in mice treated with dextran sulfate sodium and prevented the onset of colitis in IL-10(-/-) mice. This approach may lead to better methods for cost-effective and long-term management of IBD in humans.     

Calculating Dry Deposition and Canopy Exchange with the Canopy Budget Model: Review of Assumptions and Application to Two Deciduous Forests

The canopy budget model simulates the interaction of major ions within forest canopies based on throughfall and precipitation measurements. The model has been used for estimating dry deposition and canopy exchange fluxes in a wide range of forest ecosystems, but different approaches have been reported. We give an overview of model variations with respect to the time step, type of open-field precipitation data, and tracer ion, and discuss the strengths and weaknesses of different assumptions on ion exchange within forest canopies. To examine the effect of model assumptions on the calculated fluxes, nine approaches were applied to data from two deciduous forest plots located in regions with contrasting atmospheric deposition, i.e. a beech (Fagus sylvatica L.) plot in Belgium and a mixed sugar maple (Acer saccharum Marsh.) plot in Quebec. For both forest plots, a semi-annual time step in the model gave similar results as an annual time step. Na⁺ was found to be more suitable as a tracer ion in the filtering approach than Cl^? or ${\text{SO}}_4^{2 - } $ . Using bulk instead of wet-only precipitation underestimated the potentially acidifying deposition. To compute canopy uptake of ${\text{NH}}_4^ + $ and H⁺, ion exchange with K⁺, Ca²⁺, and Mg²⁺ as well as simultaneous cation and anion leaching should be considered. Different equations to allocate ${\text{NH}}_4^ + $ vs H⁺ uptake had most effect on the estimated fluxes of the cation that was less important at a plot. More research is needed on the relative uptake efficiency of H⁺, ${\text{NH}}_4^ + $ , and ${\text{NO}}_{_3 }^{\text{ - }} $ for varying tree species and environmental conditions.     

Eradication of sarcoptic mange from a Belgian pig breeding farm with a combination of injectable and in-feed ivermectin

Sarcoptes scabiei var suis was eradicated from a Belgian pig farm by using a combination of injections of ivermectin and ivermectin in the feed. The detection of mites in ear scrapings, and calculations of an average dermatitis score and a scratching index were used to evaluate the mange status of the pigs before and after the treatment. Before the treatment 28 per cent of ear scrapings of finishers were positive for the presence of mites, their average dermatitis score (ADS) was 0.92 and their scratching index was 2.0. There was a significant decrease in all three measurements during the year after the treatment, and one year after treatment, no mites were found in the ear scrapings; the ADS of the finishers was 0.31 and their scratching index was 0.16. Adult animals were negative for the presence of mites at all times, the ADS was below the cut-off level before and after treatment, and the scratching index decreased after treatment There was an economic improvement among the breeding sows and the fattening pigs. The feed consumption of the sows decreased by 5 per cent; rebreeding decreased by 4.55 per cent; average litter size increased by 0.33 live piglets born per litter and the farrowing index increased by 0.075 litters per sow per year. As a result, the production index increased by 1.34 more piglets weaned per sow per year. There was an immediate improvement in feed conversion during the five months after the treatment. The costs of the treatment were recovered within 3.7 months.     

Impact of decreasing throughfall depositions on soil solution chemistry at coniferous monitoring sites in northern Belgium

Impact of decreasing throughfall depositions on soil solution chemistry at three depths was examined in a Corsican pine (Pinus nigra Arn. ssp. laricio Poiret) stand in Ravels and a Scots pine (Pinus sylvestris L.) stand in Brasschaat within a time-span of 6 years (1992–1997). At Ravels depositions of sulphate, ammonium, nitrate, calcium, magnesium and sodium decreased by 463, 468, 169, 121, 63 and 169 mol_c ha⁻¹ per annum. At Brasschaat deposition reduction rates of sulphate, nitrate, calcium and magnesium were 198, 127, 134 and 46 mol_c ha⁻¹ per annum. In both stands the substantial reductions in inorganic nitrogen deposition were followed by a decline of nitrate fluxes leaving the forest floor and with the seepage water. The decrease of sulphate deposition since 1992 was only manifested by a decline in sulphate concentrations and fluxes during the first half of the measuring period. The increase at the end of the period could be ascribed to the fact that sulphate adsorption which was important between 1993 and 1995 finally ceased. A significant drop of calcium concentrations was discernible at both plots. Magnesium and potassium levels did only fall significantly at Brasschaat. The concentrations of base cations were largely driven by the concentrations of their counter anions, but were influenced by the base cation throughfall fluxes as well. Although a substantial reduction of throughfall acidity occurred, no improvement of the soil water acidity (acid neutralising capacity (ANC)) was noticed. ANC and molar Ca/Al followed decreasing trends at all depths in both plots. For ANC the decline was significant for the topsoil in Ravels. The decrease of molar cation Ca/Al ratio was significant for two out of three depths at both sites. The decrease was due to the drop in calcium concentrations and the raise of Al_tot in some horizons.     

Long-term (13 years) measurements of SO2 fluxes over a forest and their control by surface chemistry

Long-term fluxes of sulphur dioxide (SO₂) have been measured over a mixed suburban forest subjected to elevated SO₂ concentrations. The net exchange was shown to be highly dynamic with substantial periods of both upward and downward fluxes observed in excellent conditions for flux measurement. Upward fluxes constituted 30% of selected fluxes and appeared more frequently when the canopy was acidic. Upward fluxes were shown to be due to desorption from a drying surface or when ambient levels declined after periods of increased SO₂ exposure.The long term average SO₂ flux (F) was −59 ng SO₂ m⁻² s⁻¹ for the period 1997-2009 corresponding to an average SO₂ concentration of 12.3 μg SO₂ m⁻³ and a deposition velocity υ_d of 5 mm s⁻¹. The smallest deposition fluxes and υ_d were measured in dry conditions (−42 ng m⁻² s⁻¹ and 3.5 mm s⁻¹, resp.), which represented 57% of all cases. Wet canopies were more efficient sinks for SO₂ and a dew-wetted canopy had a smaller υ_d (6 mm s⁻¹) than a rain-wetted canopy (ca 10 mm s⁻¹). Seasonal variability reflected differences in chemical climate or canopy buffering properties. During the summer half-year when surface acidity was low due to higher NH₃/SO₂ ratios, a higher deposition efficiency (υ_d/υ_dmax) and lower non-stomatal resistance (R_w) were observed compared to winter conditions. Comparisons of R_c for different combinations of canopy wetness and surface acidity categories emphasized the importance of both factors in regulating the non-stomatal sinks of SO₂. Increased surface water acidity gradually led to a lower υ_d/υ_dmax and an increased R_c for all considered canopy wetness categories. The smallest υ_d/υ_dmax ratio and highest R_c were obtained for a dry canopy with high surface acidity. Conversely, a rain-wetted canopy was the most efficient sink for SO₂. The canopy sink strength was further enhanced by high friction velocities (u_*), optimizing the mechanical mixing into the canopy. Long-term trends were strongly coupled to changes in the NH₃/SO₂ ratio, which has clearly enhanced the deposition efficiency of SO₂ in recent years.     

Soil Water Chemistry and Revegetation of a Limed Clearcut in a Nitrogen Saturated Forest

A clearcut stand of Pinus sylvestris in Flanders (Belgium) was limed with 3 ton/ha dolomite and reforested with Acer pseudoplatanus and Fagus sylvatica. Soil water monitoring revealed an overall decrease of ion concentrations and an annual peak in September due to seasonal nitrification. Liming reduced concentrations of NO₃ ^- and Al³⁺ and raised concentrations of K⁺ and Mg²⁺ and the molar ratio of (Ca+Mg)/Al. Liming also stimulated release of SO₄ ^2-, which prevented a rise of pH, except during nitrification peaks. Liming had no effect on height increment of Fagus but stimulated Acer, which suffered from severe deficiencies of calcium (Ca), magnesium (Mg), potassium (K), and phosphorus (P) without treatment. Nitrogen (N) was not growth-limiting for Fagus or Acer and liming had no effect on N concentrations in leaves of both species. Liming had a strong impact on ground vegetation. Nutrient-demanding species expanded while species that tolerate nutrient-poor conditions decreased. It is argued that changes in ground vegetation had a greater impact on reduction of NO₃ ^- concentration in soil water than increased tree growth.     

Relationships Between Crown Condition of Beech (Fagus sylvatica L.) and Throughfall Chemistry

A two-step regression procedure was used to predict the impact of throughfall chemistry on the defoliation of Fagus sylvatica L. over a 10-year-monitoring period at three plots in northern Belgium. The impact of throughfall chemistry on crown condition was examined after accounting for influences of site, stand, climate and diseases. In a first step, defoliation was regressed on site, stand, climate and disease parameters. The residual defoliation of this standard set was correlated with 27 throughfall variables. Climatic variables of the year preceding the year of crown assessment accounted for 79% of the variation in current defoliation. Site, stand and disease factors were not included and were still part of the residual defoliation. The study of the residual defoliation revealed that high throughfall depositions of sulphate and ammonium and high throughfall ratios of SO₄/Mg enhanced defoliation.