Phosphonate—hydrogen exchange in aqueous solutions of 2H and 3H-labelled phosphonic acid

Phosphonic acid (phosphorous acid), H — PO(OH)₂, the active breakdown product in plant tissues of the systemic anti-oomycete fungicide fosetyl-aluminium was investigated in order to assay the stability of the labelled compound. There is a strong and fast isotopic exchange in unbuffered aqueous solutions of ²H — PO(OH)₂, and therefore ³H — PO(OH)₂, so that Fenn and Coffey's experiments must be reinterpreted because these authors used a stock solution of pure labelled phosphonic acid. However, it is possible to use this last compound for biological experiments under the following conditions: (1) Keeping the dry sodium salt ³H — PO(ONa)₂. 5H₂O in small flasks (100 mg, 37 MBq each) in a vacuum desiccator for individual use without fractionation; (2) using the compound at neutral or slightly acidic pH.     

Optimum selenium levels in diets high in plant‐based feedstuffs for gilthead sea bream (Sparus aurata) fingerlings

Substitution of marine ingredients (FM‐FO) by plant protein and oil sources can modify selenium (Se) levels in feeds. Se plays an important role in the antioxidative defence by forming part of selenoproteins. Se requirements of gilthead sea bream are not accurately determined; therefore, this study was conducted to define Se supplementation levels in low FM‐FO practical diets for sea bream fingerlings. A plant‐based diet containing 0.45 mg Se/kg diet was used as the basal diet. Four other diets were supplemented to contain 0.68, 0.86, 1.00 or 1.70 mg Se/kg diet, supplied as sodium selenite. Sea bream, weighing 12.6 ± 1.4 g, were distributed in triplicate groups per diet and fed for 42 days. Se supplementation up to 1.00 mg Se/kg significantly improved the growth of sea bream, whereas further increase up to 1.70 mg Se/kg diet reduced growth. The results of this study suggest that the optimum dietary levels of sodium selenite in diets with low FM‐FO with basal levels of 0.45 mg Se/kg are around 0.94 mg Se/kg to promote growth of gilthead sea bream juveniles. On the contrary, dietary levels of 1.70 mg Se/kg were found to be excessive and caused growth reduction, increased catalase expression and hydropic degeneration in the liver.     

Modelling Compaction from On-line Measurement of Soil Properties and Sensor Draught

The finite element method was used to analyse the cutting process of a sandy loam soil with medium-deep subsoiler, used as a compaction sensor, aiming to calculate the subsoiler draught for various combinations of dry bulk density, moisture content and tillage depth. The finite element results showed that draught increased with depth and dry bulk density, whereas it decreased with moisture content. A multiple linear regression analysis was performed to establish a formula for relating subsoiler draught (dependent variable) with the three independent variables. The regression equation developed was simple and had a high determination coefficient close to 0.95. An equation for prediction of dry bulk density as a function of moisture content, depth and draught was derived from the regression equation developed. This equation was used to calculate dry bulk density, for measured depth, moisture content and draught at nine different points along a single line in a meadow field of a silty clay loam soil. The predicted dry bulk density indicated that there was a considerable variation in the degree of compaction throughout the measured line. However, the on-line depth control and measurement of moisture content still need to be integrated with the on-line measurement of draught, to govern the model suitability for performing on-line detection of the spatial distribution of soil compaction, assessed as dry bulk density.     

Oxygen isotope variations at the margin of a CAI records circulation within the solar nebula

Micrometer-scale analyses of a calcium-, aluminum-rich inclusion (CAI) and the characteristic mineral bands mantling the CAI reveal that the outer parts of this primitive object have a large range of oxygen isotope compositions. The variations are systematic; the relative abundance of (16)O first decreases toward the CAI margin, approaching a planetary-like isotopic composition, then shifts to extremely (16)O-rich compositions through the surrounding rim. The variability implies that CAIs probably formed from several oxygen reservoirs. The observations support early and short-lived fluctuations of the environment in which CAIs formed, either because of transport of the CAIs themselves to distinct regions of the solar nebula or because of varying gas composition near the proto-Sun.     

Simultaneous identification of plant stresses and diseases in arable crops using proximal optical sensing and self-organising maps

The objective of this research was to detect plant stress caused by disease infestation and to discriminate this type of stress from nutrient deficiency stress in field conditions using spectral reflectance information. Yellow Rust infected winter wheat plants were compared to nutrient stressed and healthy plants. In-field hyperspectral reflectance images were taken with an imaging spectrograph. A normalisation method based on reflectance and light intensity adjustments was applied. For achieving high performance stress identification, Self-Organising Maps (SOMs) and Quadratic Discriminant Analysis (QDA) were introduced. Winter wheat infected with Yellow Rust was successfully recognised from nutrient stressed and healthy plants. Overall performance using five wavebands was more than 99%.     

The Genome sequence of the SARS-associated coronavirus

We sequenced the 29,751-base genome of the severe acute respiratory syndrome (SARS)-associated coronavirus known as the Tor2 isolate. The genome sequence reveals that this coronavirus is only moderately related to other known coronaviruses, including two human coronaviruses, HCoV-OC43 and HCoV-229E. Phylogenetic analysis of the predicted viral proteins indicates that the virus does not closely resemble any of the three previously known groups of coronaviruses. The genome sequence will aid in the diagnosis of SARS virus infection in humans and potential animal hosts (using polymerase chain reaction and immunological tests), in the development of antivirals (including neutralizing antibodies), and in the identification of putative epitopes for vaccine development.     

The value of bat-boxes in the conservation of Pipistrellus pygmaeus in wetland rice paddies

Wetlands with rice paddies are key habitats in the conservation of biodiversity in the Mediterranean Region and are potentially suitable habitats for foraging bats, since they provide food (insects) and drinking places; nevertheless, many wetlands lack natural roosting sites. A bat-box program designed to ascertain bat-box preferences was initiated in 1999 in the Ebro Delta (NE Spain), one of the most important wetlands in Europe. A total of 69 bat-boxes of two types (single and double compartment) were placed on three supports (trees, houses, and posts) facing east or west. Pipistrellus pygmaeus occupancy rates and the number of individuals per box were monitored on 16 occasions from July 2000 to February 2004. Bat-box preferences were only detected during the breeding season. Bat abundance was higher in east-facing boxes, in double-compartment boxes, and in boxes placed on posts and houses. Boxes on natural supports (trees) were avoided. Bat-box occupancy rates were higher during the breeding season (95.6%, spring-summer) due to the formation of maternity colonies. The number of individuals in bat-boxes during the breeding season increased as the study period progressed (from summer 2000 to summer 2003), suggesting a high degree of acceptance by maternity colonies of these alternative locations. Occupancy rates observed were the highest ever reported in bat-box scientific literature. This study highlights the role of bat-box programs as useful alternative management tools for the conservation of bat populations in highly productive wetland habitats where few natural roost sites are available.     

Gas chromatographic analysis of histamine in mahi-mahi (Coryphaena hippurus)

Several authors have studied histamine using gas chromatography (GC) as a tool for quantitation, but the methods used were not always suitable depending on the kind of food. Problems frequently cited include incomplete histamine elution from the columns and peak tailing. Histamine is of interest because it is the factor common to all cases of scombroid poisoning, it has physiological and biological activity, and it is a chemical indicator of fish quality. In this study a modified GC method was used to quantify histamine in mahi-mahi (Coryphaena hippurus). Mean recovery was 67% for the GC method, compared with 90% for the AOAC fluorometric method. There was a 0.96 correlation of the GC histamine values with those of the AOAC fluorometric method. A temperature program, splitless/split injection, and analyte cleanup were essential for GC properties. Histamine retention time was 8.2 min. The method allowed peak height to be used for quantitation and simultaneous analysis of cadaverine and putrescine.