The automated determination of glucosamine,galactosamine, muramic acid,and mannosamine in soil and root hydrolysates by HPLC

Amino sugars make a significant contribution to soil organic N and are mainly of microbial origin. The most important amino sugars in soil are glucosamine, galactosamine, muramic acid, and mannosamine. A method was developed for the simultaneous determination of these four amino sugars by high‐performance reverse‐phase liquid chromatography in standard solutions, soil and root hydrolysates. Pre‐column derivatization with o‐phthaldialdehyde (OPA) was used in an automated sample injector with thermostatic regulation of the reagent at 4 °C. The separation of the four amino sugars was fully satisfactory and was not disturbed by other fluorescent components in the soil and root hydrolysates.     

Soil and Sediment Geochemistry of the Iron Quadrangle, Brazil

Soils and sediments around gold ore deposit and mining sites in the Iron Quadrangle present positive As anomalies (median concentrations > 100 mg kg^-1) and wide ranges (< 20 to > 2000 mg kg^-1) even in densely populated areas. These anomalies can be related to geological structures, to hydrothermal ore deposits and to their continuous exploitation over the past three centuries. The paper presents new data on both As geochemistry and soil and sediment geochemistry in general, and discusses consequences of the encountered anomalies, their reasons and potential effects and how they compare with current screening and threshold values. While surface soil As-val-ues are reproducible at a given site, sediment anomalies show a strong seasonal variation that can be explained by tropical hydrologicai variances. Suggestions are presented on how to minimize the As-load in densely populated areas that might otherwise pose a potential health risk.     

Target-selected inactivation of the zebrafish rag1 gene

The zebrafish has become a favorite organism for genetic analysis of vertebrate development, but methods for generating mutants by reverse genetic approaches have been lacking. We report a method to obtain stable mutants of a gene based on knowledge of the gene sequence only. Parental fish were mutagenized with N-ethyl-N-nitrosourea; in 2679 F1 fish, the rag1 gene was analyzed for heterozygous mutations by resequencing. In total, we found 15 mutations: 9 resulted in amino acid substitutions and 1 resulted in a premature stop codon. This truncation mutant was found to be homozygous viable and defective in V(D)J joining. Although presumably immune deficient, these homozygous rag1 mutant fish are able to reach adulthood and are fertile. As sperm samples from all 2679 F1 fish were collected and cryopreserved, we have in principle generated a mutant library from which mutants of most zebrafish genes can be isolated.     

Beitrag zur Bestimmung der relativen Resistenz gegen Potato Virus X (PVX) an In-vitro-Pflanzen der Kartoffel

Zusammenfassung In-vitro-Pflanzen von PVX-resistenten (‘Schwalbe’, ‘Karella N’) und--anf?lligen Genotypen (‘Turbella N’, ‘Ogonjok’) in unsteriler Kultur auf Kiessubstrat wurden mechanisch inokuliert (Isolat PVX-‘Erstling’, Glasst?bchen). Eine quantitative Absch?tzung der relativen Viruskonzentration mittels ELISA 7...42 Tage nach der Inokulation (dpi) ergab bei den resistenten Genotypen im Mittel von 5 Versuchen mit 82 und 83% (70...90%) einen gegenüber den anf?lligen Formen (19 und 20%, 0...40%) signifikant h?heren Anteil Pflanzen mit gehemmter Virusvermehrung (E_{405 nm}≤1,0). Eine damit übereinstimmende Einstufung erfuhren die 4 geprüften Genotypen bei Absch?tzung der relativen Viruskonzentration an prim?rinfizierten Topf- und sekund?rinfizierten Freilandpflanzen.

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Summary The suitability of in vitro plants for determining relative (quantitative) PVX resistance was examined using resistant (‘Schwalbe’, ‘Karella N’) and susceptible (‘Turbella N’, ‘Ogonjok’) genotypes. They were grown in non-sterile gravel augmented with 2 ml of 0.45% Wopil solution (a mixture of nutrient salts with trace elements; VEB Chemiekombinat, Bitterfeld, DDR) and mechanically inoculated (glass rod) with the ‘Erstling’ isolate of PVX. The relative virus concentration in 10–15 in vitro plantlets of each genotype was estimated quantitatively using ELISA after 7, 14, 21, 28, 35 and 42 days (Fig. 1). The resistant genotypes had significantly higher proportions of plants with restricted virus multiplication (E_{405 nm}≤1.0) than the susceptible ones: means over five experiments were 82 and 83% for the resistant genotypes (70...90%) and 19 and 20% for the susceptible (0...40%)-Fig. 2. Estimation of the virus concentration in primary infected pot and secondary infected field plants of the four tested genotypes showed good agreement with established resistance rankings.

     

Using near-infrared hyperspectral images on subalpine fir board. Part 1: Moisture content estimation

Abstract

In this study, moisture content (MC) images of subalpine fir (abies lasiocarpa Hook) boards were derived from near-infrared hyperspectral images in the 947–1637 nm range. One hundred and seven cubic samples with the size of 4 cm were prepared from 14 boards. All samples were dried to various MCs during several steps until being completely dried. Hyperspectral images and weight measurements were acquired over each sample at each drying step. The samples have MC ranging from 1% to 137% (dry basis). The images were first calibrated into reflectance. Then, bad pixels were found and replaced by a corrected value using a median filter. A modified version of the boxplot method was used to find abnormal spectra that were then removed. The remaining spectra were converted into absorbance spectra. They were then split into a calibration and a validation data-set according to the boards they were extracted from to build and validate a partial least squares (PLS) regression model between the near-infrared absorbance spectra and the measured MCs. The PLS model was applied first to the sample images, then to the whole board images in order to produce 2D images of MC.     

Host Range of Tropical and Sub-tropical Isolates of Polymyxa graminis

The host range of Polymyxa graminis isolates originating from peanut clump-infested areas in India (Andhra Pradesh and Rajasthan), Pakistan and Senegal was studied on monocotyledonous and dicotyledonous cultivated species, using known quantities of sporosori as inoculum. Profuse multiplication occurred only on some graminaceous species, but the various isolates showed different host specificity. All the isolates produced high infection on sorghum and pearl millet, and all but one isolate from Rajasthan infected maize. Wheat, rye and barley were susceptible to some of the tested isolates. The isolates from Rajasthan and Pakistan produced moderate to severe infection on at least one of these species. On rice, groundnut and sugar beet, only traces of infection by some isolates were detected, whereas no infection was observed on mustard and sunflower. Differences of susceptibility in Pennisetum spp. and Sorghum spp. were demonstrated. The variations in host specificity among isolates from peanut clump-infested areas may result from an adaptation of P. graminis populations to various biotopes. The implications of these results for the management of peanut clump disease are discussed. A comparison of the host ranges of isolates of P. graminis and P. betae from temperate areas demonstrated that distinct types of Polymyxa might be identified based on their relative ability to multiply on susceptible species. Nevertheless, overlapping in the host ranges among the different Polymyxa types, characterised by distinct ecological and genomic features, raises doubts about the host range as a classification criterion for the Polymyxa genus.