Status of black grass (Alopecurus myosuroides) resistance to acetyl-coenzyme A carboxylase inhibitors in France

We assessed the contributions of target site‐ and non‐target site‐based resistance to herbicides inhibiting acetyl‐coenzyme A carboxylase (ACC) in Alopecurus myosuroides (black grass). A total of 243 A. myosuroides populations collected across France were analysed using herbicide sensitivity bioassay (24 300 seedlings analysed) and ACC genotyping (13 188 seedlings analysed). Seedlings resistant to at least one ACC‐inhibiting herbicide were detected in 99.2% of the populations. Mutant, resistant ACC allele(s) were detected in 56.8% of the populations. Among the five resistant ACC alleles known in A. myosuroides, alleles containing an isoleucine‐to‐leucine substitution at codon 1781 were predominant (59.5% of the plants containing resistant ACC alleles). Comparison of the results from herbicide sensitivity bioassays with genotyping indicated that more than 75% of the plants resistant to ACC‐inhibiting herbicides in France would be resistant via increased herbicide metabolism. Analysis of herbicide application records suggested that in 15.9% of the populations studied, metabolism‐based resistance to ACC‐inhibiting herbicides was mostly selected for by herbicides with other modes of action. Our study revealed the importance of non‐target site‐based resistance in A. myosuroides. Using herbicides with alternative modes of action to control populations resistant to ACC‐inhibiting herbicides, the recommended management approach, may thus be jeopardised by the widespread occurrence of metabolism‐based resistance mechanisms conferring broad‐spectrum cross‐resistance.     

Coupled ferric oxides and sulfates on the Martian surface

The Mars Exploration Rover (MER), Opportunity, showed that layered sulfate deposits in Meridiani Planum formed during a period of rising acidic ground water. Crystalline hematite spherules formed in the deposits as a consequence of aqueous alteration and were concentrated on the surface as a lag deposit as wind eroded the softer sulfate rocks. On the basis of Mars Express Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA) orbital data, we demonstrate that crystalline hematite deposits are associated with layered sulfates in other areas on Mars, implying that Meridiani-like ground water systems were indeed widespread and representative of an extensive acid sulfate aqueous system.     

Asteroid 21 Lutetia: low mass, high density

Asteroid 21 Lutetia was approached by the Rosetta spacecraft on 10 July 2010. The additional Doppler shift of the spacecraft radio signals imposed by 21 Lutetia's gravitational perturbation on the flyby trajectory were used to determine the mass of the asteroid. Calibrating and correcting for all Doppler contributions not associated with Lutetia, a least-squares fit to the residual frequency observations from 4 hours before to 6 hours after closest approach yields a mass of (1.700 ± 0.017) × 10(18) kilograms. Using the volume model of Lutetia determined by the Rosetta Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) camera, the bulk density, an important parameter for clues to its composition and interior, is (3.4 ± 0.3) × 10(3) kilograms per cubic meter.     

Les vitamines du groupe B chez les végétaux

Résumé Les parenchymes chlorophylliens, lieux de synthèses très actives, sont très riches en vitamines du groupe B, vitamines qui sont les éléments essentiels des coenzymes du métabolisme cellulaire. Dans la feuille d'épinard par exemple, on trouve, par kilogramme de substance sèche, en chiffres ronds, 20 mg de riboflavine, 14 mg de thiamine, 10 d'acide folique, 20 d'acide pantothénique, 65 d'acide nicotinique, 25 de pyridoxine. Dans un tissu étiolé comme le chou de Bruxelles, ces taux sont déjà deux fois plus faibles environ. Dans les tissus de réserve, où l'activité métabolique est très faible, les taux observés sont 10 ou 20 fois plus faibles; les vitamines restent à des taux élevés dans les germes des graines, tandis que les endospermes, les cotylédons, sont pauvres; la riboflavine devient 3 à 5 fois plus rare que la thiamine. Au moment de la germination, la riboflavine triple ou quadruple en quelques jours, les autres vitamines augmentent aussi, sauf la thiamine. Les jeunes germinations, les jeunes pousses sont des aliments riches en vitamines. Au moment de la formation du grain des céréales, les vitamines émigrent des feuilles, des tiges, vers le grain, lorsqu'il est encore jeune; le grain “laiteux” est riche en vitamines; le grain m?r, bourré d'amidon, est pauvre en vitamines. Les variétés à grains sucrés, à grains ridés, chez le ma?s, le pois, ont, pour ces raisons, à maturité, des taux de vitamines 3 à 10 fois plus élevés que les variétés amylacées. Les variétés de céréales sont d'autant plus riches en vitamines que le germe et son écusson, et aussi la couche à aleurone, sont plus gros.

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Summary The chlorophyll parenchymes, highly active centres of synthesis, are very rich in “B”-vitamins. These vitamins constitute the essential substances of the coenzyme of the cell metabolism. In the spinach leaf e.g., one finds approximately 20 mg of riboflavine, 14 mg of thiamine, 10 mg of folic acid, 20 mg of panthotenic acid, 65 mg of nicotinic acid, and 25 mg of pyridoxine per 1 kg of dry matter. In etiolated tissue, such as brussel sprouts, these values are already approx. twice lower. In reserve tissue, where there is only very little metabolic activity, the ascertained values are by 10–20 times lower. In grain germs, on the other hand, the vitamin values are extremely high; there is, however, a scarcity in endosperms and in cotyledons. Riboflavine will be found 3–5 times less often than thiamine. During germination, riboflavine will multiply threefold or fourfold, and that within a few days time. The other vitamin values are also increased except for thiamine. Both young germs and young sprouts as foodstuff are very rich in vitamins. As the grain is developing, the vitamins wander off from the leaves and stalks to the grain, as long as that grain is still young. Thus, the “lacteous” grain is rich in vitamins. The ripened grain is rich in starch, but poor in vitamins. Therefore, in the case of maize (corn) and peas, sugar and rippled varieties, when ripe, have vitamin values that are approximately 3 to 10 times above those of amylaceous varieties. The bigger the germ, the husk and the aleurone layer are in varieties of cereals, the richer in vitamins they will be.

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Zusammenfassung Die Chlorophyll-Parenchyme, sehr aktive Synthese-Zentren, sind sehr reich an Vitaminen der B-Gruppe. Diese Vitamine sind die wesentlichen Bestandteile der Coenzyme des Zell-Stoffwechsels. Im Spinatblatt z.B. findet man in 1 kg Trockensubstanz rund 20 mg Riboflavin, 14 mg Thiamin, 10 mg Fols?ure, 20 mg Pantothens?ure, 65 mg Nikotins?ure und 25 mg Pyridoxin. In etiolierten Geweben, wie z.B. beim Rosenkohl, sind diese Werte schon ungef?hr zweimal niedriger. In Reservegeweben, wo die Stoffwechselaktivit?t sehr gering ist, sind die beobachteten Werte 10 oder 20 mal geringer. In Kornkeimlingen sind die Vitaminwerte sehr hoch; sie liegen jedoch sehr niedrig im Endosperm und in den Cotyledonen. Riboflavin findet sich in drei bis fünfmal geringeren Mengen als Thiamin. Beim Keimen verdreifacht oder vervierfacht sich das Riboflavin in wenigen Tagen. Auch die übrigen Vitaminwerte steigen an, mit Ausnahme des Thiamins. Die jungen Keimlinge und die jungen Triebe sind sehr vitaminreiche Nahrungsmittel. Bei der Bildung des Getreidekorns wandern die Vitamine aus den Bl?ttern und Stengeln ab zum Korn, sofern bezw. solange es noch jung ist. Das “milchige” Korn ist reich an Vitaminen. Das reife Korn ist voller St?rke, aber vitaminarm. Zucker- und Runzelmais-Sorten und Mark-Erbsen haben daher bei Reife Vitaminwerte, die drei bis zehnmal h?her liegen als st?rkereiche Sorten. Die Getreidesorten sind umso reicher an Vitaminen, je gr?sser der Keimling, Randund Aleuronschichten der Caryopsen sind.

     

Libri novi

Ohne Zusammenfassung     

Antimicrobial drug susceptibility of Staphylococcus intermedius clinical isolates from canine pyoderma

A total of 50 Staphylococcus intermedius strains isolated in France from canine pyodermas in 2002 were investigated for their susceptibility to various antimicrobial drugs. Antimicrobial susceptibility was assessed using a 2-fold serial dilution method in Mueller-Hinton agar, and the minimal inhibitory concentrations (MICs) were determined. About 62% of the 50 strains tested were producers of beta-lactamase and categorized as penicillin-resistant. About 26% demonstrated resistance to sulphonamides, 46% to oxytetracycline, 30% to chloramphenicol, 28% to streptomycin, kanamycin, neomycin or erythromycin, 22% to clindamycin, 6% to doxycycline, 2% to gentamicin, enrofloxacin, marbofloxacin or pradofloxacin. Acquired resistance was not observed to a clavulanic acid-amoxicillin combination, oxacillin, cephalosporins (cephalexin, ceftiofur and cefquinome), trimethoprim, a sulphamethoxazole-trimethoprim combination and florfenicol. About 42% were simultaneously resistant to three or more antimicrobial classes (multiresistance). All isolates with acquired resistance to erythromycin were also resistant to streptomycin and neomycin/kanamycin. About 22% of isolates exhibited cross-resistance between erythromycin and clindamycin and all clindamycin-resistant isolates also exhibited resistance to erythromycin. Resistance to penicillin, oxytetracycline and chloramphenicol was also positively associated with resistance to erythromycin and streptomycin.     

Principes et applications de la chromatographie en phase vapeur

Resumé La chromatographie en phase vapeur ne doit pas être considérée comme une distillation fractionnée, mais comme une séparation des constituants d'un mélange basée sur un phénomène d'adsorption des différentes substances à l'état de vapeur sur la paroi du tube, conformément `a la th%eorie émise par HenriDevaux.L'auteur passe en revue les avantages présentés par cette méthode qu'il a lui-même pratiquée longuement: à savoir sa grande sensibilité, rendant possible la séparation de quantités de l'ordre de 10-⁷g; sa grande rapidité, permettant d'effectuer certaines analyses, exigeant autrefois plusieurs jours, en quelques minutes; sa réproductibilité et sa fidélité; l'absence de phénomènes d'azéotropie, et la possibilité qu'elle donne de séparer des isomères de position.La chromatographie en phase vapeur a permis notamment de réaliser des progrès substanciels dans l'analyse des corps gras, du sang humain, et l'identification de certains alcools jusqu'alors insoupçonnés, dans les phénomènes de fermentation.

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Summary Vapour-phase chromatography should not be considered as a fractional distillation but as a separation of the constituents of a mixture, based on the phenomenon of adsorption of different substances as vapours on the walls of the tube, in conformity with the theory exposed by HenriDevaux. The author reviews the advantages offered by this method, put into practice by him a long time, i.e.: its great sensibility, making possible the isolation of quantities as minute as 10^–7 g; its speed, making possible some analyses that would normally have taken several days, in a few minutes; its reproducibility and fidelity; the absence of any phenomenon of azeotropy, and the possibility to separate positional isomers.Vapour-phase chromatography has rendered possible, more particularly, substancial advances in the analysis of fats, human blood, in the perfume industry, and the identification of certain alcohols, the precense of which has been up to now unsuspected, in fermentation phenomena.

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Zusammenfassung Die Chromatographie in der Dampfphase soll nicht als eine fraktionierte Destillation aufgefaßt werden, sondern vielmehr als ein Trennverfahren der Bestandteile einer Mischung auf Grund eines Adsorptionseffektes auf der Rohrwandung der verschiedenen Substanzen in gasförmigen Zustand, entsprechend der Theorie von H.Devaux. Der Autor erklärt die Vorzüge dieser Analysenmethode, welche er gründlich angewandt hat; große Empfindlichkeit, die Quantitäten in der Größenordnung von 10-⁷ g zu trennen erlaubt, große Schnelligkeit, so daß gewisse Analysen, die früher mehrere Tage erforderten, in wenigen Minuten durchgeführt werden können, Wiederholbarkeit und treue Wiedergabe, Fortfall azeotropischer Einflüsse, Trennung der Isomere.Die Chromatographie in der Dampfphase bringt unter anderem wesentliche Fortschritte für die Analysenergebnisse der Fette und Öle, des menschlichen Blutes, für die Feststellung bestimmter Alkohole in Gärungsprozessen.

     

Deux Associations Internationales pour la recherche scientifique dans le domaine de la chimie végétale

Sans résumé