Experimental infection of a bovine model with human isolates of Mycobacterium avium subsp. paratuberculosis

Mycobacterium avium subsp. paratuberculosis (Map), the etiologic agent of Johne's disease (JD) in ruminants, has been implicated in the pathogenesis of Crohn's disease (CD) in humans. We developed a bovine ileal cannulation model to facilitate comparison of the immune response to Map and the mechanisms of pathogenesis in cattle and humans. Initial studies showed a T cannula could be maintained for up to a year in calves without inducing inflammation or adversely affecting intestinal function. Map introduced through the cannula established a persistent low level of infection without inflammation. Infection elicited an immune response to Map antigens detectable by flow cytometry. Further studies now show the cannulation model can be used with cows during the later stage of infection, affording access to the target tissue at all stages of infection. The studies also revealed no difference in infectivity or immunogenicity of isolates of Map obtained from cattle or humans with CD. Comparison of the immune response to Map during the early and late stages of infection using PCR, flow cytometry and QRT-PCR, showed the immune response early in the disease process is dominated by CD4 T cells. A CD8 response is delayed but comparable at later stages of infection. Genes for pro-inflammatory cytokines IFN-γ and the recently identified genes encoding IL-17 and IL-22 are up regulated in infected animals. These findings reveal that both human and bovine isolates of Map can establish infection and induce similar immune responses in a bovine model. They also reveal the cytokine responses elicited in cattle are similar to those implicated in CD pathogenesis.     

Exploring Ground Vegetation Change for Different Deposition Scenarios and Methods for Estimating Critical Loads for Biodiversity Using the ForSAFE-VEG Model in Switzerland and Sweden

The ForSAFE-VEG model was used to investigate the impacts of climate change and air pollution scenarios on soil chemistry and ground vegetations composition. In particular, the model involves a ground vegetation model incorporating plant changes to ambient site conditions in terms of climate and chemistry, but the model also incorporate competition between the different plant groups. The model was validated against observed values and reproduced observations of tree growth, soil chemistry, and ground vegetation compositions to satisfaction. The results show that the ground vegetation reacts strongly to changes in air pollution, in particular nitrogen as well as to climate change with major shifts in plant composition. A procedure for estimating critical loads for nitrogen, using ground vegetation biodiversity as criterion, was tested and the method seems operable. It suggests that if we want to protect the present biodiversity of the ground vegetation, this will face significant difficulties because of permanent climate change that induced changes in the ecosystem. We conclude that the reference state for ground vegetation biodiversity is rather to be sought for in the future, hopefully using models, than in the past or present.     

Cochliomyia hominivorax myiasis in a colony of stray cats (Felis catus Linnaeus, 1758) in Rio de Janeiro, RJ

Cochliomyia hominivorax infestation in domestic cats of an urban colony in the city of Rio de Janeiro is described. The overall prevalence over the period 2001-2005 was 12.5%. Only adult cats were found infested and among these, most cases were observed in males (28%) (p < or = 0.05). The most frequently infested areas of the cats' bodies were the face and nape of the neck. Most lesions were found on the front part of the body of adult males (80%), suggesting that myiasis occur in consequence of competitive fighting wounds.     

Multi-step ahead soil temperature forecasting at different depths based on meteorological data: Integrating resampling algorithms and machine learning models

Direct soil temperature (ST) measurement is time-consuming and costly;thus,the use of simple and cost-effective machine learning (ML) tools is helpful.In this study,ML approaches,including KStar,instance-based K-nearest learning (IBK),and locally weighted learning (LWL),coupled with resampling algorithms of bagging (BA) and dagging (DA)(BA-IBK,BA-KStar,BA-LWL,DA-IBK,DA-KStar,and DA-LWL) were developed and tested for multi-step ahead (3,6,and 9 d ahead) ST forecasting.In addition,a linear regress...     

Boron Nutrition of Four Sweet Pepper Cultivars Grown in Boron-Deficient Soil

ABSTRACT

In a greenhouse study, boron (B) application significantly increased dry-matter yield of sweet pepper (Capsicum annum L.) cultivars (‘California Wonder,’ ‘Anahein,’ ‘Narwala,’ and ‘2573’) grown in a B-deficient (hot-water extractable, 0.28 B mg kg^?1), calcareous soil of the Shujabad series (Typic Ustochrepts). Five rates of B, ranging from 0 to 8 mg B kg^?1 soil, were applied as H₃BO₃ along with adequate basal fertilization of nitrogen (N), phosphorus (P), potassium (K), and zinc (Zn). Four plants of sweet pepper were transplanted in each pot, two of which were harvested after three weeks of transplanting and the other two after six weeks. Maximum crop biomass was produced with ～1 mg B kg^?1, but application of higher rates proved toxic, resulting in dry-matter yield reductions. The four cultivars significantly differed in relative growth rate (RGR) and relative accumulation rate of B (RARB). Cultivar ‘2573’ showed the highest RGR while ‘Anahein’ showed the highest RARB. Relative accumulation rate was positively correlated (R² = 0.83) with dry-matter yield of four cultivars. Critical B concentration in sweet pepper whole shoots was 69 mg B kg^?1 for three-week-old plants and 49 mg B kg^?1 for six-week-old plants.     

Functional relationships of nodulation response and biomass production at nursery stages of two fast-growing, leguminousmultipurpose tree species in Bangladesh: Albizia saman and Leucaena leucocephala

This study was carried out to assess the relationship of the status of nodulation （i.e., the number of nodules, their shape and size） in root and biomass production of plant growth parameters （i.e., number of leaves, root and shoot lengths, root biomass and shoot biomass） in Albizia saman and Leucaena leucocephala. The assessment started 60 days after seeding. The study revealed that nodulation response and biomass production in both species showed significant dif- ferences over time （p 〈 0.05） in all variables except in the root-shoot ratio （oven-dry） of L. leucocephala. The study also showed significant differences （p 〈 0.05） in nodule formation and biomass production at the end of the study period be- tween the two species except in the number of nodules and leaves and the green root-shoot ratio. There were strong pos- itive correlations between nodule formation and biomass production, i.e., the number of nodules and the age of plants, the number of nodules and leaves, as well as the number of nodules and biomass （root biomass and shoot biomass） in both species. The results obtained using principal component analysis （PCA） and correlation coefficients of the different characteristics of nodulation and biomass production were similar in both species. The PCA showed that shoot biomass （shoot green weight and shoot oven-dry weight） is positively correlated with PC1 （with an eigenvalue of 7.50） and root length is positively correlated with PC2 （with an eigenvalue of 0.19） in the case of A. saman. In the case of L. leucocephala, the PCA revealed that root biomass （root green weight and root oven-dry weight）, shoot biomass and shoot length are also positively correlated with PC1, while nodule formation and the number of leaves are positively correlated with PC2 （with an eigenvalue PC1 of 6.92 and PC2 of 0.49）.     

Influence of Nitric Oxide Application on Some Biochemical Aspects,Endogenous Hormones,Minerals and Phenolic Compounds of Vicia faba Plant Grown under Arsenic Stress

Arsenic is a non-essential and toxic heavy metal, which can cause physiological disorder in plants. The present study was undertaken to examine the possible roles of sodium nitroprusside (SNP, a donor of NO) in protection against oxidative damage due to arsenic (As) toxicity in faba bean (Vicia faba L.) plants. In this study, we measured physiochemical parameters (photosynthetic pigments, lipid peroxidation, endogenous hormones, minerals and phenolic contents) in faba bean plants exposed to AS (100, 200 and 400 µM) alone or combined with NO (100 µM). The results showed that application of all concentrations of arsenic (100, 200 and 400 µM) induced decrease on growth parameters, seed yield, photosynthetic pigments, phytohormones, minerals contents (N^3?, P^3?, K⁺, Ca²⁺?and Mg²⁺) as compared to control plants but increased lipid peroxidation, Na?⁺ and total phenolic compounds fraction. Foliar application of 100 µM NO reversed the inhibition induced by As treatment. In addition, arsenic was undetected in harvested seeds at all applied concentrations of arsenic. Therefore, it could be concluded that NO might account for the alleviating effect of As stress on Vicia faba plants.     

Effects of deficit irrigation scheduling on yields and soil water balance of irrigated maize

This paper presents the findings of the effect of some selected deficit irrigation scheduling practices on irrigated maize crop in a sub-catchment in south western part of Tanzania. Field experiments, in which maize (TMV1-ST) variety was planted under total irrigation, were conducted during the dry seasons of 2004 and 2005. Surface irrigation method was used and the crop was planted in basins. The seasonal water applied ranged from 400 to 750 mm. Soil moisture content from both cropped and bare soils, leaf area index, dry matter, and grain yields were measured. The dry matter yield ranged between 6,966 and 12,672 kg/ha, and grain yields obtained were between 1,625 and 4,349 kg/ha. The results showed that deficit irrigation at any crop growth stage of the maize crop led to decrease in dry matter and grain yields, seasonal evapotranspiration and deep percolation. Deficit irrigation in any one growth stage of the maize crop only seems to affect grain production and no significant effect on biomass production, but deficit irrigation that spanned across two or more growth stages affect both biomass and grain production drastically. Crop water use efficiency (WUE) and Irrigation water use efficiency (IWUE) were strongly influenced by the number of growth stages in which deficit irrigations were applied and how critical the growth stages were to moisture stress rather than the amount of irrigation water applied. While maximum WUE was obtained under full irrigation, maximum IWUE was obtained in the deficit irrigation treatment at vegetative growth stage, which suggest that IWUE may be improved upon by practicing deficit irrigation at the vegetative growth stage of the maize crop.