Microbial indicators exhibit a high spatial heterogeneity which often masks comparison of the effects of different soil management treatments. It is therefore desirable to use a proper sampling ...design which integrates spatial heterogeneity at field level. Thus, the objectives were: (1) to study the spatial heterogeneity of biological and chemical soil variables, and (2) with obtained maps of spatial variability to test different sampling strategies to assess the usefulness of this ‘new’ soil map unit. 63 soil samples were collected according to a 10 m × 10 m grid on a 0.48 ha plot. On each of these samples, 10 variables were measured: soil water content, cation exchange capacity (CEC), organic carbon (OC) and total nitrogen (N), C/N, soil microbial biomass (SMB), labile soil organic matter (LOM), mineralisable C (C
min) and N (N
min), inverse of specific respiratory activity (1/SRA = SBM/C
min). The spatial heterogeneity of each variable was charted with geostatistics. The biological variables exhibited spatial variability of the same order of magnitude as physicochemical parameters. From the maps, zones with different levels of organic matter, microbial biomass and specific respiratory activity were identified. The spatial patterns of SMB and SRA were related to CEC (positively for SMB and negatively for SRA), pointing out the effects of soil protection on microbial biomass and availability of organic substrates. The definition of these zones for a pool of variables (OC, N, SMB, LOM, CEC) is useful at 3 levels: (1) to record the initial values of the measured variables for each plot, (2) to integrate these zones as blocks in experimental design for future experiments, and (3) to focus analysis of specific biological mechanisms such as activity of micro-organisms.
A solvent free microwave hydrodiffusion and gravity extraction (MHG) of flavonol content from onion (
Allium cepa L.) was studied. Effectiveness of this innovative method in extraction of onion total ...phenolic content, total quercetin (TQ), quercetin aglycon (QA), quercetin-3,4′-diglucoside (QDG), quercetin-4′-monoglucoside (Q4G), quercetin-3-monoglucoside (Q3G), kaempferol (KMF) and myricetin (MRT) have been evaluated and compared with conventional solvent extraction. Microwave extraction offers important advantages like shorter extraction time (23
min), cleaner feature (no solvent or water used) and extraction of valuable onion crude juice retaining fresh organoleptic properties with higher phenolic content (58.29
mg
GAE/g
DW) at optimized power (500
W). Microwave extraction resulted significant yield (81.5%) with 41.9% of flavonol contents, with better retain of remaining flavonoids (55.9%) in residues of onions. QDG (239.7
mg/100
g
DW) and Q4G (82.55
mg/100
g
DW) have been reported the main flavonol in this study. Minor quantities of QA (traces), Q3G (4.22
mg/100
g
DW) and KMF (3.99
mg/100
g
DW) were also detected in microwave onion extracts.
1
S 16257 is a new bradycardic agent. Its electropharmacological profile has been compared to that of the known bradycardic compound UL‐FS 49 (Zatebradine). Intracellular recordings of action ...potentials (APs) were performed with conventional glass microelectrodes.
2
In the rabbit isolated sino‐atrial node (SAN) tissue, S 16257 and UL‐FS 49 (1 μm, 3 μm and 10 μm) were equipotent in slowing spontaneous APs firing predominantly by decreasing the rate of diastolic depolarization (at 3 μm, – 23.8 ± 3.9% and – 27.9 ± 2.6%, respectively). For the two compounds a maximal effect was obtained at 3 μm. In these preparations, action potential duration at 50% of total repolarization (APD50) was more affected by UL‐FS 49 than S 16257 at any concentration tested (at 3 μm, + 8.9 ± 2.9% and + 29.1 ± 3.7% for S 16257 and UL‐FS 49, respectively; P ≤ 0.01).
3
To estimate the direct effects on AP duration, driven cardiac preparations were exposed to these agents. In guinea‐pig papillary muscles, paced at a frequency of 1 Hz, increasing concentrations of S 16257 or UL‐FS 49 (0.1 to 10 μm, 30 min exposure for each concentration) slightly prolonged AP repolarization. This prolongation was more marked for UL‐FS 49 (at 1 μm, + 6.1 ± 0.6% and + 11.2 ± 1.3% elevation of APD50, for S 16257 and UL‐FS 49, respectively).
4
Application of UL‐FS 49 (3 μm) to rabbit Purkinje fibres, triggered at a frequency of 0.25 Hz, induced a marked prolongation of APD50 and APD90 (+ 149.4 ± 51.2% and + 86.0 ± 15.4%, respectively). S 16257 (3 μm) induced only a weak prolongation of AP (+ 14.1 ± 5.0% and + 14.8 ± 3.3% for APD50 and APD90, respectively) significantly smaller than in the case of UL‐FS 49.
5
These results show that S 16257 slows the rate of spontaneous AP firing in isolated SAN mainly by a reduction of the diastolic depolarization of the cells, which suggests an inhibition of the pace‐maker current (If). S 16257 and UL‐FS 49 are equipotent in their bradycardic effect but S 16257 is more specific as it induces less increase in myocardial repolarization time.
Tillage modifies soil structure and crop residue distribution and in turn affects the ability of soil micro-organisms to degrade soil organic matter and release nutrients for crop growth. In organic ...farming, soil microbiological activity is of primary importance as nutrient supply is mainly dependent on the degradation of soil organic matter by soil micro-organisms. The aim of this work was therefore to study, in organic farming, the effects of four tillage systems mouldboard ploughing (MP), shallow mouldboard ploughing (SMP), reduced tillage (RT) and shallow soil tillage (ST) on soil structure, soil microbial biomass (SMB) and its potential activity (Cmin) during the first year following the treatments. To study simultaneously the effects of soil structure modifications and crop residue distribution on SMB and Cmin, we adopted a sampling scheme based on a morphological description of soil profiles. We distinguished and sampled compacted and non-compacted clods (Δ and Γ clods) at three depths (0-5, 5-15 and 15-30 cm). This method enabled us to have a precise estimation of the effects of tillage treatments on SMB and Cmin. MP reduced compacted zones and limited unfavourable conditions for microbial growth and enabled a homogenous distribution of SMB in the soil profile. At the opposite, the ST increased compacted zones in the soil profile and limited SMB development below the top few centimetres. The SMP and the RT systems appeared as intermediate techniques. RT seemed to be a conservation tillage technique which could be used in organic farming.
Durant la Renaissance, le dialogue est partout, dans tous les champs du savoir et de l'expression « littéraire » comme dans tous les pays d'Europe. Ses formes sont d'une déconcertante diversité, ...s'adaptant et se déployant selon des temporalités elles-mêmes très variables. L'on pourrait s'amuser à dire, en partant du constat qu'il faut attendre le dernier tiers du XVIe siècle pour voir apparaître ses premières théorisations (Carlo Sigonio, Sperone Speroni, Torquato Tasso), que, pendant longtemps, s'il est partout, le dialogue n'est à proprement parler nulle part : il reste sans territoire défini, ni même sans doute définissable, dans l'univers des genres de l'écrit et a fortiori dans ses relevés cartographiques. Sans territoire circonscrit au sens propre non plus, puisque né dans sa forme « moderne » en Italie (avec Pétrarque comme initiateur), mais en un âge que caractérisent la densité et la continuité des échanges entre lettrés de différentes « nations », il semble étendre inexorablement et durablement son aire d'extension. Absolument et définitivement sans territoire ? L'observateur attentif pourra cependant distinguer des « couleurs locales » : outre le cas, italien, le mieux connu sans doute, le plus logiquement marqué par des studia humanitatis, y aurait-il un filon espagnol, marqué par un esprit de sérieux couplé à la promotion résolue des langues vulgaires, castillan au premier chef, et volontiers tourné vers les horizons géographiques nouveaux ? Une veine française, très sensible à l'hybridation, voire à la déconstruction ? Et qu'en est-il des aires laissées de côté, l'anglophone notamment ?
The selective dopamine D3 receptor agonist, 7-OH-DPAT ((+)-7-hydroxy-2-(di-n-propylamino)tetralin) and the novel naphthofurane, S 14297 ((+)-7-(N,N-dipropylamino)-5,6,7,8-tetrahydro- ...naphtho(2,3b)dihydro,2,3-furane), bound with high affinity and selectivity to recombinant, human dopamine D3 versus D2 receptors stably transfected into Chinese hamster ovary cells: Ki values = 2 versus 103 nM for 7-OH-DPAT and 13 versus 297 nM for S 14297. In contrast, the putative dopamine D3 receptor antagonist, AJ 76 (cis-(+)-5-methoxy-1-methyl-2-(n- propylamino)tetralin), displayed low affinity and selectivity for dopamine D3 versus D2 sites (70 versus 154 nM). 7-OH-DPAT (0.01-0.16 mg/kg s.c.) provoked hypothermia in rats, an action abolished by S 14297 (0.04-0.63 mg/kg s.c.) and, less potently, by AJ 76 (0.16-2.5 mg/kg s.c.). S 14297 (20.0 mg/kg s.c.) did not modify prolactin secretion. These data suggest that dopamine D3 receptors mediate hypothermia in the rat and that S 14297 acts as a selective antagonist at these sites.
Soil tillage modifies the location of crop residues and soil structure and affects microbial populations and activities such as mineralization of soil organic matter. The aim of this work was to ...compare the effect of two tillage systems (traditional mouldboard ploughing, LT, and reduced tillage, TR) on crop residues distribution and soil structure as well as their consequences on soil microbial biomass (BM), the potential activity of C mineralization (Cmin) and soil bacterial community structure (through T-RFLP). In order to study simultaneously the effects of soil structure modifications and crop residues distribution on these microbial parameters we used a stratified sampling scheme based on a morphological characterisation of soil structure (figure 1 and 2). Compacted and non compacted clods (respectively named Δ and Γ clods) were distinguished and sampled at three depths : 0-7, 7-17 and 17-30 cm. BM and Cmin were homogeneously distributed in the soil profile in the LT treatment, whereas they showed a vertical stratification in TR (figure 3). Our sampling scheme pointed out that BM and Cmin were affected by both burying depth of crop residues and soil structure. They decreased with soil compaction, but this effect appeared only in soil layers where crop residues were buried, suggesting that these microbial parameters are modified firstly by organic matter availability and secondly by soil structure. Bacterial community structure was also modified by crop residues distribution and soil compaction (figure 4). Indeed, the bacterial community structure of the 0-7 cm soil layer differed markedly from the others soil layers, for LT and TR. However, the bacterial community structure exhibited a high spatial variability at the field scale and further studies are needed to investigate the effects of soil tillage on soil microbial communities.
El trabajo del suelo modifica la repartición de los residuos de cultivo y la estructura del suelo y afecta en consecuencia los microorganismos del suelo (número, estructura genética de las poblaciones) así que las funciones que aseguran enl primero plano la mineralización de la materia orgánica. El objetivo está estudiar el efecto de estas modificaciones generadas por dos técnicas contrastadas de trabajo del suelo : una labranza tradicional (LT) y un trabajo del suelo reducido (TR). Las variables estudiadas están biomasa microbiana del suelo (BM), el potencial de mineralización del carbono (Cmin) y la estructura de las comunidades bacterianas del suelo evaluada por T-RFLP. Con el fin de tomar en cuenta el efecto simultáneo de las modificaciones de la estructura del suelo y de las de la repartición de los residuos de cultivo, se adoptó una estrategia de muestreo estratificada al seno del perfil de cultivo. Para eso, se midieron los indicadores microbianos en terrones compactados y no compactados (respectivamente llamados Δ y Γ) tomados a tres profundidades (0-7, 7-17 y 17-30 cm). La BM y el Cmin se reparten de manera homogénea en la profundidad de la labranza para LT mientras que presentan une estratificación vertical en TR. El nivel de compactación del suelo modifica igualmente estas variables que disminuyen al seno de los horizontes donde se entierran los residuos de cultivo. Por otra parte, se modificó la estructura de las comunidades bacterianas igualmente por la profundidad de enterramiento de los residuos de cultivo y por la estructura del suelo. Sin embargo, este indicador parece afectado por una variabilidad espacial importante, cuyo no se controlan todos los factores. Los efectos del trabajo del suelo sobre las comunidades microbianas merecerían un estudio mas profundizado.
Le travail du sol modifie la répartition des résidus de culture et la structure du sol et affecte par conséquent les microorganismes du sol (nombre, structure génétiques des populations) ainsi que les fonctions qu’ils assurent au premier rang desquelles la minéralisation de la matière organique. L’objectif est d’étudier l’effet de ces modifications engendrées par deux techniques contrastées de travail du sol : un labour traditionnel (LT) et un travail réduit (TR). Les variables étudiées sont la biomasse microbienne du sol (BM), le potentiel de minéralisation u carbone (Cmin) et la structure des communautés bactériennes du sol évaluée par T-RFLP. Afin de prendre en compte l’effet simultané des modifications de la structure du sol et celles de la répartition des résidus de culture, une stratégie d’échantillonnage stratifiée au sein du profil cultural a été adoptée. Pour cela, les indicateur microbiens ont été mesurés sur des mottes compactées et non-compactées (respectivement baptisées Δ et Γ) prélevées à 3 profondeurs : 0-7, 7-17 et 17-30 cm. La BM et le Cmin sont répartis de façon homogène sur la profondeur de labour pour LT tandis qu’ils présentent une stratification verticale en TR. Le niveau de tassement des communautés bactériennes est modifié également par la profondeur d’enfouissement des résidus de culture et par la structure du sol. Cependant, cet indicateur semble affecté par une variabilité spatiale importante, dont on ne maîtrise pas tous les facteurs. Les effets du travail du sol sur les communautés microbiennes mériteraient une étude plus approfondie.
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