In tropical agroecosystems, limited N availability remains a major impediment to increasing yield. A 15N-recovery experiment was conducted in 13 diverse tropical agroecosystems. The objectives were to determine the total recovery of one single 15N application of inorganic or organic N during three to six growing seasons and to establish whether the losses of N are governed by universal principles. Between 7 and 58% (average of 21%) of crop N uptake duringthe first growing season was derived from fertilizer. On average, 79% of crop N was derived from the soil. When 15N-labeled residues were applied, in the first growing season 4% of crop N was derived from the residues. Average recoveries of 15N- labeled fertilizer and residue in crops after the first growing season were 33 and 7%, respectively. Corresponding recoveries in the soil were 38 and 71 %. An additional 6% of the fertilizer and 9.1 % of the residue was recovered by crops during subsequent growing seasons. There were no significant differences in total 15N recovery (average 54%) between N from fertilizer and N from residue. After five growing seasons, more residue N (40%) than fertilizer N (18%) was recovered in the soil, better sustaining the soil organic matter N content. Long-term total recoveries of 15N-labeled fertilizer or residue in the crop and soil were similar. Soil N remained the primary source of N for crops. As higher rainfall and temperature tend to cause higher N losses, management practices to improve N use efficiency and reduce losses in wet tropical regions will remain a challenge.

/pdf/multiseason-recoveries-of-organic-and-inorganic-nitrogen-15-4f0y1nfsb8.pdf

Multiseason Recoveries of Organic and Inorganic Nitrogen-15 in Tropical Cropping Systems

Ganoderma lucidum is a medicinal fungus belonging to the Polyporaceae family which has long been known in Japan as Reishi and has been used extensively in traditional Chinese medicine. We report the isolation and identification of the 26-oxygenosterols ganoderol A, ganoderol B, ganoderal A, and ganoderic acid Y and their biological effects on cholesterol synthesis in a human hepatic cell line in vitro. We also investigated the site of inhibition in the cholesterol synthesis pathway. We found that these oxygenated sterols from G. lucidum inhibited cholesterol biosynthesis via conversion of acetate or mevalonate as a precursor of cholesterol. By incorporation of 24,25-dihydro-[24,25-3H2]lanosterol and [3-3H]lathosterol in the presence of ganoderol A, we determined that the point of inhibition of cholesterol synthesis is between lanosterol and lathosterol. These results demonstrate that the lanosterol 14α-demethylase, which converts 24,25-dihydrolanosterol to cholesterol, can be inhibited by the 26-oxygenosterols from G. lucidum. These 26-oxygenosterols could lead to novel therapeutic agents that lower blood cholesterol.

Effect of 26-Oxygenosterols from Ganoderma lucidum and Their Activity as Cholesterol Synthesis Inhibitors

Detection and Diversity of Fungi from Environmental Samples: Traditional Versus Molecular Approaches.- Functional Genomic Approaches for Mycorrhizal Research.- Automated Fluoroscence Sequencing and Troubleshooting.- mRNA Quantitation Using Real Time PCR.- Laboratory Practice for the Production of Polyclonal and Monoclonal Antibodies.- Modern Techniques for Analyzing Immunological Responses.- Transcriptome Analysis.- RNAi Technology: a Tool for Functional Validation of Novel Genes.- Molecular Matchmaking: Techniques for Biomolecular Interactions.- Environmental Proteomics: Extraction and Identification of Protein in Soil.- DGGE and RISA Protocols for Microbial Community Analysis in Soil.- Soil Microbial Community Structure and Function Assessed by FAME, PLFA and DGGE - Advantages and Limitations.- Measurement of Microbial Biomass and Activity in Soil.- Immuno-Technology for the Localization of Acid Phosphatase Using Native Gel Bands in Piriformospora indica and Other Soil Microorganisms.- Use of Short Oligonucleotide Primers in Random Amplified Polymorphic DNA Techniques for Species Identification.- Co-Cultivation with Sebacinales.- Quantitative Histochemistry: a Forgotten Tool with New Applications.- Ion Cyclotron Resonance Fourier Transform Mass Spectrometry for Non-Targeted Metabolomics of Molecular Interactions in the Rhizosphere.- Application of Terminal-Restriction Fragment Length Polymorphism for MolecularAnalysis of Soil Bacterial Communities.- Molecular Symbiotic Analysis Between Arabiopsis thaliana and Piriformospora indica.- Biophysical Phenomics Reveals Functional Building Blocks of Plants Systems Biology: a Case Study for the Evaluation of the Impact of Mycorrhization with Piriformospora indica.- Analysis of the Plant Protective Potential of the Root Endophytic Fungus Piriformospora indica in Cereals.- Members of Sebacinales Confer Resistance Against Heavy Metal Stress in Plants.- Screening of Plant Growth-Promoting Rhizobacteria.- Research Methods in Arbuscular Mycorrhizal Fungi.- Field Trials of Bioinoculants.

Advanced techniques in soil microbiology

Metabolomic fingerprinting enabled by ambient mass spectrometry employing a direct analysis in real time (DART) ion source coupled to a medium–high resolution/accurate mass time-of-flight mass spectrometer (TOFMS) was used as a tool for differentiation between chickens fed by feed that contained 5–8 % (w/w) of chicken bone meal (a banned component) and those representing a reference group, i.e. grown otherwise under the same conditions. In the first step, the sample extraction and DART–TOFMS instrumental conditions were optimized to obtain the broadest possible representation of ionizable compounds occurring in the extracts obtained from chicken muscle and feed on which experimental animals were grown. To this end, a simultaneous (all-in-one) extraction procedure was developed employing water and cyclohexane mixture as the extraction solvents. Under these conditions both polar as well as non-polar metabolites were isolated within a single extraction step. In the next step, metabolomic fingerprints of a large set of chicken muscle and feed extracts were acquired. In the final phase, the experimental data were statistically evaluated using principal component analysis and orthogonal partial least squares discriminant analysis. In general, differentiation of chicken muscle according to diet (feed with and without the addition of chicken bone meal) was feasible. Additional experiments conducted after 6 months confirmed applicability of this approach. Correct classification was obtained based on the assessment of polar as well as non-polar extracts fingerprints. However, the analysis of non-polar extracts showed that the pattern of triacylglycerols is more prone to seasonal variability and/or type of raw materials used during feed preparation which obscures the bone meal impact to some extent.

Application of direct analysis in real time ionization–mass spectrometry (DART–MS) in chicken meat metabolomics aiming at the retrospective control of feed fraud

Matrix-assisted laser desorption/ionization with time-of-flight mass spectrometry is used to examine the formation of N-pyroglutamate (pGlu) in single, identified neurons from Aplysia. Six pGlu peptides are identified in the R3-14 and the R15 neurons that result from in vivo processing of peptides containing either Glu or Gln at their respective N-termini. Moreover, we show that Glu-derived pGlu is not a sample collection or measurement artifact. The pGlu peptides are detected in isolated cell bodies, regenerated neurites in culture, interganglionic connective nerves, cell homogenates, and collected releasates. We also demonstrate that R3-14 cells readily convert a synthetic N-Glu peptide to its pGlu analogue, indicating the presence of novel enzymatic activity.

https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1471-4159.1999.0720676.x

Formation of N-pyroglutamyl peptides from N-Glu and N-Gln precursors in Aplysia neurons.

Mass Spectrometry Analysis

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