Direct prediction of site-specific lime requirement of arable fields using the base neutralizing capacity and a multi-sensor platform for on-the-go soil mapping

Precision Agriculture - Liming agricultural fields is necessary for counteracting soil acidity and is one of the oldest operations in soil fertility management. However, the best management...     

Beta-N-methylamino-l-alanine: LC-MS/MS Optimization,Screening of Cyanobacterial Strains and Occurrence in Shellfish from Thau,a French Mediterranean Lagoon

β-N-methylamino-l-alanine (BMAA) is a neurotoxic non-protein amino acid suggested to be involved in neurodegenerative diseases. It was reported to be produced by cyanobacteria, but also found in edible aquatic organisms, thus raising concern of a widespread human exposure. However, the chemical analysis of BMAA and its isomers are controversial, mainly due to the lack of selectivity of the analytical methods. Using factorial design, we have optimized the chromatographic separation of underivatized analogues by a hydrophilic interaction chromatography coupled to tandem mass spectrometry (HILIC-MS/MS) method. A combination of an effective solid phase extraction (SPE) clean-up, appropriate chromatographic resolution and the use of specific mass spectral transitions allowed for the development of a highly selective and sensitive analytical procedure to identify and quantify BMAA and its isomers (in both free and total form) in cyanobacteria and mollusk matrices (LOQ of 0.225 and 0.15 µg/g dry weight, respectively). Ten species of cyanobacteria (six are reported to be BMAA producers) were screened with this method, and neither free nor bound BMAA could be found, while both free and bound DAB were present in almost all samples. Mussels and oysters collected in 2009 in the Thau Lagoon, France, were also screened, and bound BMAA and its two isomers, DAB and AEG, were observed in all samples (from 0.6 to 14.4 µg/g DW), while only several samples contained quantifiable free BMAA.     

Effects of temporal floral resource availability and non-crop habitats on broad bean pollination

Landscape Ecology - Flowering plants can enhance wild insect populations and their pollination services to crops in agricultural landscapes, especially when they flower before the focal crop....     

Effect of gamma-sterilization and autoclaving on soil organic matter structure as studied by solid state NMR, UV and fluorescence spectroscopy

Sterilized soil is often used, for example in degradation studies, sorption experiments, microbiological tests and plant test systems, to distinguish between microbial processes and abiotic reactions. The most commonly used technique for sterilization is autoclaving of the soil. Another technique is irradiation with high‐level gamma radiation (γ‐radiation). One major drawback of sterilization procedures is the possible alteration of the structure of soil components, for example the organic matter. A change in the chemical structure of the soil organic matter can cause different reactions in the above‐mentioned experiments and hence interfere with the aim of clearly distinguishing between biotic and abiotic processes. Two soils (Gleyic Cambisol and Orthic Luvisol) were sterilized by two γ‐irradiation procedures (4 kGy hour^?1 for 9 hours and 1.3 kGy hour^?1 for 27 hours) and repeated autoclaving at 121°C. Gentle physical aggregate fractionation of the sterilized soils revealed a decrease in the aggregation of the soil, which was reflected in an increase of the clay fraction. Subsequent analysis of the aqueous phase revealed much more dissolved organic matter (DOM) in the γ‐sterilized and autoclaved soils than in the untreated soils. Ultraviolet (UV) and fluorescence spectra of the DOM showed a decrease in the aromaticity and polycondensation of the dissolved organic carbon (DOC). ¹³C cross‐polarization/magic‐angle spinning nuclear magnetic resonance (¹³C‐CP/MAS NMR) spectra of the unfractionated soils and their respective soil fractions before and after sterilization showed that the most important change occurred in the carbohydrate and N‐alkyl region, the main components of microorganisms. In general, the impact of the sterilization method was stronger for autoclaving. The γ‐sterilized soils and fractions displayed both fewer and smaller changes in the soil organic matter.     

Assessing phenotypic,biochemical, and molecular diversity in coriander (<Emphasis Type="Italic">Coriandrum sativum</Emphasis> L.) germplasm

Our goals for this research were to elucidate phenotypic and biochemical diversity in coriander (Coriandrum sativum L.) populations maintained at the North Central Regional Plant Introduction Station in Ames, IA, and examine relationships between amplified fragment length polymorphism (AFLP) markers and patterns of phenotypic and biochemical diversity. Phenotypic and biochemical traits were evaluated, and analyses of variance and mean comparisons were performed on the resulting data sets. Euclidean distances from phenotypic (PD) and biochemical (BD) data were estimated, and modified Rogers’ distances (RD) were estimated for 80 polymorphic AFLP markers. These data were subjected to cluster analyses (CA) and principal components analyses (PCA), to reveal patterns among populations, and to analyses of molecular variance (AMOVA) for grouping patterns from PD and BD by using the 80 polymorphic AFLP markers. Resulting phenotypic, biochemical, and molecular distance matrices were also compared by applying Mantel tests. Our results describe significant differences among populations for all the phenotypic traits, and dendrograms obtained from PD and BD revealed complex phenetic patterns, as did groups from PCA. The primary seed essential oils and nearly all fatty-acid components were identified and their abundance measured; the primary chemical constituents of corresponding PCA groups are described herein. Molecular evidence supported phenotypic and biochemical subgroups. However, variation attributed among subgroups and groups was very low (∼4–6%), while variation among populations within groups was intermediate (∼24–26%), and that within populations was large (∼69–70%), reflecting weak differentiation among subgroups and groups, which was confirmed by values for fixation indices. Phenotypic subgroups described in this study differed somewhat from previous infraspecific classifications. Weak correlations were found between the phenotypic and biochemical matrices and between the biochemical and AFLP matrices. No correlation was found between the phenotypic and AFLP matrices. These results may be related to coriander’s phenotypic plasticity, its wide range in lifecycle duration, its predominantly allogamous reproductive biology, a human-selection process focused on special traits that may be controlled by few genes, and the widespread trade of coriander seeds as a spice, which may result in dynamic, poorly differentiated molecular variation, even when phenotypic and biochemical differentiation is easily documented. The U. S. Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.     

Elemental compositions of comet 81P/Wild 2 samples collected by Stardust

We measured the elemental compositions of material from 23 particles in aerogel and from residue in seven craters in aluminum foil that was collected during passage of the Stardust spacecraft through the coma of comet 81P/Wild 2. These particles are chemically heterogeneous at the largest size scale analyzed ( approximately 180 ng). The mean elemental composition of this Wild 2 material is consistent with the CI meteorite composition, which is thought to represent the bulk composition of the solar system, for the elements Mg, Si, Mn, Fe, and Ni to 35%, and for Ca and Ti to 60%. The elements Cu, Zn, and Ga appear enriched in this Wild 2 material, which suggests that the CI meteorites may not represent the solar system composition for these moderately volatile minor elements.     

Colonizing Islands of water on dry land—on the passive dispersal of fish eggs by birds

The vast majority of global freshwater ecosystems are small lakes with less than 100 m² surface area. These lakes are often unconnected to other water bodies but frequently host fish populations. Existing explanations for how fish colonize such remote habitats often involve birds as vectors transporting fish eggs as propagules. In this study, we aim to quantify the prevalence of these explanations among relevant societal groups as well as their scientific knowledge basis. We analyzed entries in online blogs and forums and surveyed the opinions of local stakeholders and decision makers using a questionnaire. To collect published scientific knowledge, we conducted a structured literature review. Our results reveal a discrepancy between commonly found beliefs and the empirical knowledge supporting those beliefs: Dispersal of fish eggs by water birds was overall the most frequent explanation online and in the questionnaire. In the scientific literature, however, we found hardly any empirical research on passive fish egg dispersal. We propose research directions for how to close this gap of knowledge and suggest that future empirical studies on passive fish egg dispersal may be inspired by existing work on passive dispersal in aquatic invertebrates. Mitigating the belief‐evidence discrepancy on fish dispersal will be essential to better understand the patterns of fish biodiversity across landscapes, to counteract its losses, and inform management strategies for invasive fish species.