Gas-chromatographic Separation of Organic Acids and Electrophoretic Determination of Phosphatases from VA Mycorrhizal Roots

A report is given on methods for separation and identification of organic acids, including phenolic acids, and on the determination of phosphatases from VA mycorrhizal (VAM) roots. For gas-chromatographic preparation of the samples containing the organic acids silylation and methylation were tested, as well as various solvents and silylating reagents. Columns of different polarity were examined for their separation properties. Gas- chromatographic separation of the acids was incomplete on the packed column OV 7. With the capillary column PVMS 54 separation was much better, but improvements are still needed. Mycorrhiza-specific phosphatases (MSP) appearing as three bands were found by electrophoresis with porosity-gradient gels in mycorrhizal roots of Allium, Sorghum and Eupatorium plants. In these three species each MSP was located at the same position. Inoculated onion roots enzymatically digested with cellulase and pectinase showed no root-specific phosphatases, but still revealed MSP. Further improvements in electrophoresis techniques are being investigated.     

Degradation of neohesperidin dihydrochalcone by human intestinal bacteria

The degradation of neohesperidin dihydrochalcone by human intestinal microbiota was studied in vitro. Human fecal slurries converted neohesperidin dihydrochalcone anoxically to 3-(3-hydroxy-4-methoxyphenyl)propionic acid or 3-(3,4-dihydroxyphenyl)propionic acid. Two transient intermediates were identified as hesperetin dihydrochalcone 4'-beta-d-glucoside and hesperetin dihydrochalcone. These metabolites suggest that neohesperidin dihydrochalcone is first deglycosylated to hesperetin dihydrochalcone 4'-beta-d-glucoside and subsequently to the aglycon hesperetin dihydrochalcone. The latter is hydrolyzed to the corresponding 3-(3-hydroxy-4-methoxyphenyl)propionic acid and probably phloroglucinol. Eubacterium ramulus and Clostridium orbiscindens were not capable of converting neohesperidin dihydrochalcone. However, hesperetin dihydrochalcone 4'-beta-d-glucoside was converted by E. ramulus to hesperetin dihydrochalcone and further to 3-(3-hydroxy-4-methoxyphenyl)propionic acid, but not by C. orbiscindens. In contrast, hesperetin dihydrochalcone was cleaved to 3-(3-hydroxy-4-methoxyphenyl)propionic acid by both species. The latter reaction was shown to be catalyzed by the phloretin hydrolase from E. ramulus.     

3,4-Dimethylpyrazole phosphate (DMPP) – a new nitrification inhibitor for agriculture and horticulture

3,4-Dimethylpyrazole phosphate (DMPP) is a new nitrification inhibitor with highly favourable properties. It has undergone thorough toxicology and ecotoxicology tests and application-technology experiments, and has been shown to have several distinct advantages compared to the currently used nitrification inhibitors. Application rates of 0.5-1.5 kg ha^-1 are sufficient to achieve optimal nitrification inhibition. DMPP can significantly reduce NO₃^- leaching, without being liable to leaching itself. DMPP may reduce N₂O emission, apparently without a negative effect on CH₄ oxidation of the soil. The use of DMPP-containing fertilizers can improve yield. This offers the possibility of saving mineral fertilizer N, reducing the number of N-application rounds, and obtaining higher crop yields with current fertilizer-N rates.     

The suitability of ELISA for the detection of antibodies against Mycobacterium avium ssp. paratuberculosis in bulk milk samples from Rhineland-Palatinate

Paratuberculosis or Johne's Disease, caused by Mycobacterium avium subspecies paratuberculosis (MAP), is a notifiable disease in Germany which produces enormous economical losses in dairy farms. At present,there is no confirmed data about the actual number of infected livestock herds in Germany. A countrywide monitoring program to evaluate the prevalence in dairy herds would only be economically feasible on the basis of bulk milk testing. In this study, we evaluated two ELISA test kits (SVANOVIR Ptb-ELISA, IDEXX-M.pt. Milk test kit) for the detection of antibodies against MAP in bulk milk. First, the Paratuberculosis-status of the herd derived from the history of the farm was used as a gold standard. Paratuberculosis-negative farms were tested negative with each test, but paratuberculosis-positive or Paratuberculosis-serologically-positive farms were detected only in one case (Svanovir) or three cases (IDEXX), respectively. Even if inconclusive results are counted as positive, 82.9 % (Svanovir) or 80 % (IDEXX) of the paratuberculosis-positive or serologically paratuberculosis positive farms were not detected. Nevertheless, a re-validation of both ELISAs by means of ROC and TG-ROC analyses was attempted by searching for ideal cut-offs, optimised for bulk milk. If a high specificity was selected, no acceptable sensitivity could be reached.The best results were obtained using a sensitivity of 32.3 % at a specificity of 100 % (Svanovir). With a small change of the cut-off value, the sensitivity increased to still 57 %, but this reduced the specificity to 67 %. Similar results were obtained with the IDEXX-ELISA. We then evaluated the Svanovir-ELISA for the detection of bulk milk samples on the basis of the current paratuberculosis prevalence within 69 dairy herds from Rhineland-Palatinate using individual milk samples.When the bulk milk samples were tested in two different laboratories using the same ELISA, considerable differences in the results became evident. Nearly all samples were tested with a higher relative test result in one laboratory, which often led to differences in the classification of the prevalence levels.The estimated within-herd seroprevalences ranged between 0 % and 37 %.There was little agreement between the historical paratuberculosis herd status and the within-herd prevalence in milk serum, as reflected in a kappa-index of 0.146.To determine the sensitivity and specificity of the bulk milk ELISA by ROC and TG-ROC analysis, 116 bulk milk samples were used that had been obtained from the 69 dairy herds participating in the study. The optimal ratio of sensitivity (81 %) and specificity (77 %) relative to a "gold standard" was obtained when the cut-off was set at the 10 % level. These values for sensitivity and specificity were better than those obtained in an evaluation of the same ELISA in which the historical Paratuberculosis herd-status was used as a "gold standard." The results of this study question the suitability of the available ELISAs for bulk milk testing.Taking into account that the Svanovir-ELISA for individual milk samples has a sensitivity of 60 96% relative to the blood serum variant of the test, and that the latter has also a limited sensitivity due to the pathogenesis of paratuberculosis, the available test systems examined in this Study do not seem to be suitable for herd diagnosis by using bulk milk samples.     

Thermal imaging for assessment of maize water stress and yield prediction under drought conditions

Maize production in Thailand is increasingly suffering from drought periods along the cropping season. This creates the need for rapid and accurate methods to detect crop water stress to prevent yield loss. The study was, therefore, conducted to improve the efficacy of thermal imaging for assessing maize water stress and yield prediction. The experiment was carried out under controlled and field conditions in Phitsanulok, Thailand. Five treatments were applied, including (T1) fully irrigated treatment with 100% of crop water requirement (CWR) as control; (T2) early stress with 50% of CWR from 20 days after sowing (DAS) until anthesis and subsequent rewatering; (T3) sustained deficit at 50% of CWR from 20 DAS until harvest; (T4) late stress with 100% of CWR until anthesis and 50% of CWR after anthesis until harvest; (T5) late stress with 100% of CWR until anthesis and no irrigation after anthesis. Canopy temperature (FLIR), crop growth and soil moisture were measured at 5-day-intervals. Under controlled conditions, early water stress significantly reduced maize growth and yield. Water deficit after anthesis had no significant effect. A new combination of wet/dry sponge type reference surfaces was used for the determination of the Crop Water Stress Index (CWSI). There was a strong relationship between CWSI and stomatal conductance (R² = 0.90), with a CWSI of 0.35 being correlated to a 64%-yield loss. Assessing CWSI at 55 DAS, that is, at tasseling, under greenhouse conditions corresponded best to the final maize yield. This linear regression model validated well in both maize lowland (R² = 0.94) and maize upland fields (R² = 0.97) under the prevailing variety, soil and climate conditions. The results demonstrate that, using improved standardized references and data acquisition protocols, thermal imaging CWSI monitoring according to critical phenological stages enables yield prediction under drought stress.     

The shifting ground of swidden agriculture on Palawan Island,the Philippines

Recent literature describing the process and pathways of the agrarian transition in Southeast Asia suggests that the rise of agricultural intensification and the growth of commodity markets will lead to the demise of swidden agriculture. This paper offers a longitudinal overview of the conditions that drive the agrarian transition amongst indigenous swidden cultivators and migrant paddy farmers in central Palawan Island, the Philippines. In line with regional agrarian change, we describe how a history of conservation policies has criminalized and pressured swidden farmers to adopt more intensive “modern” agricultural practices. We examine how indigenous swidden cultivators adjust their practice in response to recent changes in policies, security of harvests, and socio-cultural values vis-à-vis intensification. Rather than suggest that this transition will lead to the demise of swidden, results reveal that farmers instead negotiate a shifting ground in which they lean on and value swidden as a means of negotiating agrarian change.     

Combining metal oxide affinity chromatography (MOAC) and selective mass spectrometry for robust identification of <Emphasis Type="Italic">in vivo</Emphasis> protein phosphorylation sites

Background  

Protein phosphorylation is accepted as a major regulatory pathway in plants. More than 1000 protein kinases are predicted in the Arabidopsis proteome, however, only a few studies look systematically for in vivo protein phosphorylation sites. Owing to the low stoichiometry and low abundance of phosphorylated proteins, phosphorylation site identification using mass spectrometry imposes difficulties. Moreover, the often observed poor quality of mass spectra derived from phosphopeptides results frequently in uncertain database hits. Thus, several lines of evidence have to be combined for a precise phosphorylation site identification strategy.     

Suppression of cytokine-inducible nitric oxide synthesis during intraperitoneal Meth A tumor growth

Nitric oxide (NO*) synthesis is induced within many tumors. The time course of NO* synthesis was evaluated during intra-peritoneal Meth A fibrosarcoma progression. While increasing macrophage recruitment into ascites was noted, inducible nitric oxide synthase (iNOS) antigen and function peaked between days 3-6 after tumor implantation. The capacity of cells to respond to LPS and IFNgamma stimulation was markedly depressed on day 9 and 11. Cellular proliferation correlated in an inverse fashion with levels of NO* synthesis. Electron paramagnetic resonance spectroscopy and nitrotyrosine immunostaining failed to show accumulation of characteristic target cell lesions induced by NO*. These findings lead us to conclude that NO* production was increasingly suppressed during Meth A tumor progression. Depression of NO* production did not correlate with levels of the inhibitory cytokines TGFbeta and IL-10, but could be partially overcome by addition of sepiapterin (a tetrahydrobiopterin prodrug). Thus, depletion of essential co-factors necessary for iNOS function may contribute to depressed NO* responses during cancer progression.     

Sustaining livelihoods in a palm oil enclave: Differentiated gendered responses in East Kalimantan,Indonesia

With large tracts of forested land planned for, or already converted to, industrial palm oil concessions, there is a need to better understand the gendered implications for, and responses by, communities affected by such landscape change. This paper examines the differentiated gendered responses and livelihood strategies of Dayak Modang women and men in a hamlet in East Kalimantan, Indonesia, surrounded by industrial palm oil plantations. Informed by feminist political ecology, we investigate how the compounding impact of industrial oil palm – the basis and outcome of enclavement – curtails livelihood options and reinforces gender differentiation in terms of access to and use of customary resources. Gendered inequalities and food insecurity dynamics emerge as a result. We show how, however, that despite gendered exclusions, Dayak Modang women use their own knowledge and practices to diversify livelihoods to negotiate emerging constraints over resource access and use. Our paper demonstrates that ways in which Dayak women ‘sustain livelihoods’ reflects forms of everyday negotiations and resistance to intensifying constraints over life and livelihood.