Effect of aggregation on potassium flux in a structured soil

The effect of aggregation on nutrient release by diffusion has been determined for potassium for a well structured P horizon of a Vertic Cambisol. The results clearly demonstrate that homogenization of soil material produces an increase of the potassium release by diffusion compared to that from single natural aggregates. The bigger the aggregates are the smaller is the potassium release related to unit mass per unit time, because of the longer flow paths in bigger aggregates. If the results are related to unit surface, bigger aggregates deliver significantly more potassium because of the smaller inter-aggregate surfaces. Differences between potassium release out of differently sized aggregates further depend on the kind of extraction liquid. Values of the effective diffusion coefficient for potassium are smaller for single aggregates than for undisturbed soil samples.     

Fusarium langsethiae and mycotoxin contamination in oat grain differed with growth stage at inoculation

European Journal of Plant Pathology - High levels of mycotoxins are occasionally observed in Norwegian oat grain lots. Mycotoxins of primary concern in Norwegian oats are deoxynivalenol (DON)...     

Synthesis and Cytotoxicity Evaluation of Spirocyclic Bromotyrosine Clavatadine C Analogs

Marine-originated spirocyclic bromotyrosines are considered as promising scaffolds for new anticancer drugs. In a continuation of our research to develop potent and more selective anticancer compounds, we synthesized a library of 32 spirocyclic clavatadine analogs by replacing the agmatine, i.e., 4-(aminobutyl)guanidine, side chain with different substituents. These compounds were tested for cytotoxicity against skin cancer using the human melanoma cell line (A-375) and normal human skin fibroblast cell line (Hs27). The highest cytotoxicity against the A-375 cell line was observed for dichloro compound 18 (CC₅₀ 0.4 ± 0.3 µM, selectivity index (SI) 2). The variation of selectivity ranged from SI 0.4 to reach 2.4 for the pyridin-2-yl derivative 29 and hydrazide analog of 2-picoline 37. The structure–activity relationships of the compounds in respect to cytotoxicity and selectivity toward cancer cell lines are discussed.     

Assessing the effects of subtropical forest fragmentation on leaf nitrogen distribution using remote sensing data

Subtropical forest loss resulting from conversion of forest to other land-cover types such as grassland, secondary forest, subsistence crop farms and small forest patches affects leaf nitrogen (N) stocks in the landscape. This study explores the utility of new remote sensing tools to model the spatial distribution of leaf N concentration in a forested landscape undergoing deforestation in KwaZulu-Natal, South Africa. Leaf N was mapped using models developed from RapidEye imagery; a relatively new space-borne multispectral sensor. RapidEye consists of five spectral bands in the visible to near infra-red (NIR) and has a spatial resolution of 5 m. MERIS terrestrial chlorophyll index derived from the RapidEye explained 50 % of the variance in leaf N across different land-cover types with a model standard error of prediction of 29 % (i.e. of the observed mean leaf N) when assessed on an independent test data. The results showed that indigenous forest fragmentation leads to significant losses in leaf N as most of the land-cover types (e.g. grasslands and subsistence farmlands) resulting from forest degradation showed lower leaf N when compared to the original indigenous forest. Further analysis of the spatial variation of leaf N revealed an autocorrelation distance of about 50 m for leaf N in the fragmented landscape, a scale corresponding to the average dimension of subsistence fields (2,781 m²) in the region. The availability of new multispectral sensors such as RapidEye thus, moves remote sensing closer to widespread monitoring of the effect of tropical forest degradation on leaf N distribution.     

Correlation of antigen-specific IFN-γ responses of fresh blood samples from Mycobacterium avium subsp. paratuberculosis infected heifers with responses of day-old samples co-cultured with IL-12 or anti-IL-10 antibodies

Paratuberculosis is a chronic infection of the intestine of ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). Early stage MAP infection can be detected by measuring cell-mediated immune responses using the interferon gamma (IFN-γ) assay. Whole blood samples are cultured overnight with specific MAP antigens followed by quantification of IFN-γ by ELISA. It is recommended that the time interval from sampling to culture does not exceed eight hours but addition of the co-stimulating cytokine interleukin 12 (IL-12) or anti-IL-10 antibodies to culture have been demonstrated to enhance IFN-γ responses of cultures stimulated with Johnin purified protein derivative (PPDj). Here we examined the correlation of IFN-γ production in response to PPDj and 15 recombinant antigens in day-old blood samples from heifers 10-21 months of age from a MAP infected herd with addition of either recombinant bovine IL-12 or anti-bovine IL-10 antibody with IFN-γ production in sample day samples. IFN-γ responses of sample day samples showed high correlation with responses to some antigens in day-old samples with addition of IL-12 or anti-IL-10 antibodies to cultures, indicating that day-old protocols can be applied as an alternative to the conventional IFN-γ protocol. Immunogenicity of the novel antigens was generally low for day-old samples. The most promising antigen using the day-old protocol with addition of IL-12 was latency protein LATP-2 as correlations, immunogenicity and diagnostic specificity collectively was high. The latency protein LATP-1 was the most promising antigen in the day-old protocol with addition of anti-IL-10 antibodies.     

Use of the johnin PPD interferon-gamma assay in control of bovine paratuberculosis

Although the interferon-gamma (IFN-γ) assay for measurements of cell-mediated immune (CMI) responses to paratuberculosis PPD (johnin) has been available for close to 20 years, the assay has not yet emerged as the long desired test to identify infected animals at an early time point. Among other issues, this relates to problematic interpretation of the test results and maybe an over-expectation of what can be deducted from this kind of test given the chronic nature and slow development of infection of paratuberculosis. Over a number of years a modified IFN-γ assay with addition of recombinant bovine IL-12 to the PPDj stimulation of blood samples from the heifer group in more than 20 Danish dairy herds which also perform surveillance of MAP antibodies in milk have been performed. The results indicate that IFN-γ assay results are specific for paratuberculosis, but the IFN-γ assay result of an individual animal cannot establish whether the animal is infected or predict the future progression of disease in this animal. The IFN-γ assay should thus be used on a group of animals to test the level of exposure to paratuberculosis bacteria the animals have experienced, and thereby assist in maintaining rational in-herd management procedures and in the establishment of paratuberculosis status of a given herd. Indeed, for any diagnostic test applied in paratuberculosis, both the diagnostic target condition and the purpose of the diagnostic testing must be considered before any meaningful estimates of sensitivity or specificity can be given.