Chemical attributes of a Hapludox soil after nine years of pig slurry application

The objective of this study was to evaluate the pig slurry application effects on chemical attributes of a Hapludox soil managed under no-tillage system. Treatments consisted of 50, 100 and 200 m³ ha-1 per year of pig slurry application, and a control with replacement of P and K exported through harvested grains. Attributes related to soil chemical reaction, exchange complex, and nutrient contents were determined in soil samples collected in the ninth year of experimentation from 0 - 0.025, 0.025 - 0.05, 0.05 - 0.10, 0.10 - 0.20, 0.20 - 0.40 and 0.40 - 0.60 m soil depths. The continuous application of high doses of pig slurry on the Oxisol surface under no-tillage acidifies the soil and increases Al, P, Cu, and Zn contents down to 0.2-m depth, and K levels down to 0.6-m depth.

Molecular epidemiology of Pseudomonas aeruginosa in intensive care units over a 10-year period (1998-2007).

Pseudomonas aeruginosa is one of the leading nosocomial pathogens in intensive care units (ICUs). The source of this microorganism can be either endogenous or exogenous. The proportion of cases as a result of transmission is still debated, and its elucidation is important for implementing appropriate control measures. To understand the relative importance of exogenous vs. endogenous sources of P. aeruginosa, molecular typing was performed on all available P. aeruginosa isolated from ICU clinical and environmental specimens in 1998, 2000, 2003, 2004 and 2007. Patient samples were classified according to their P. aeruginosa genotypes into three categories: (A) identical to isolate from faucet; (B) identical to at least one other patient sample and not found in faucet; and (C) unique genotype. Cases in categories A and B were considered as possibly exogenous, and cases in category C as possibly endogenous. A mean of 34 cases per 1000 admissions per year were found to be colonized or infected by P. aeruginosa. Higher levels of faucet contamination were correlated with a higher number of cases in category A. The number of cases in category B varied from 1.9 to 20 cases per 1000 admissions. This number exceeded 10/1000 admissions on three occasions and was correlated with an outbreak on one occasion. The number of cases considered as endogenous (category C) was stable and independent of the number of cases in categories A and B. The present study shows that repeated molecular typing can help identify variations in the epidemiology of P. aeruginosa in ICU patients and guide infection control measures.

Recognition of insect eggs in Arabidopsis modulates defense responses

Plants activate direct and indirect defenses in response to insect egg deposition. In Arabidopsis thaliana, oviposition by the butterfly Pieris brassicae triggers cellular and molecular changes that are similar to the changes caused by biotrophic pathogens. Even though this innate immune response did not affect egg survival in Arabidopsis, we could show that different insect eggs elicit specific gene expression changes. Additionally, egg- induced necrosis could be observed in a variety of plants from different families ranging from dicotyledonous plants to monocots, suggesting that insect-egg detection by plants is a widespread mechanism and that different insect species contain elicitors of immune responses. Extracts from caterpillars and eggs contain elicitors that co-purified over several extraction steps. Chemical fractionation of caterpillar extracts lead to the characterisation of an active compound that was determined to be a triglyceride by NMR analysis. The exact structure of the side chains as well as the elicitor's presence in insect eggs have yet to be confirmed.We also found that the plant defense signal salicylic acid (SA) accumulates at the site of oviposition. This is unexpected, as the SA pathway controls the defense against fungal and bacterial pathogens whereas it negatively interacts with the jasmonic acid (JA) pathway, which is crucial for the defense against herbivores. Application of P. brassicae or Spodoptera littoralis egg extract onto leaves reduced the induction of insect-responsive genes after challenge with caterpillars, suggesting that egg-derived elicitors suppress plant defense. Consequently, larval growth of the generalist herbivore S. littoralis, but not of the specialist P. brassicae, was significantly higher on plants treated with egg extract than on control plants. In contrast, suppression of gene induction and enhanced S. littoralis performance were not found in the SA-deficient mutant sid2-l, indicating that SA mediates this phenomenon. These data reveal an intriguing facet of the crosstalk between SA- and JA-signalling pathways and suggest that insects have evolved a way to suppress the induction of defense genes by laying eggs that release elicitors. Additionally, we demonstrated that mutants of known crosstalk regulators, including nprl-1, tga2356, ein2-l and wrky70-l, are not affected in egg-induced suppression of herbivore defenses. JA treatment was not able to alleviate this SA/JA negative crosstalk, suggesting that this suppression operates through a novel mechanism downstream of JA biosynthesis.

Bioactivity of Piper extracts on Tuta absoluta (Lepidoptera: Gelechiidae) in tomato

The objective of this work was to evaluate the bioactivity of ethanolic leaf extracts from four species of the genus Piper against the tomato leafminer Tuta absoluta (Lepidoptera: Gelechiidae) under laboratory conditions. The evaluated species were: P. amalago var. medium, P. glabratum, P. mikanianum, and P. mollicomum. In the initial screening assay (extract concentration of 2,000 mg L-1), all tested extracts caused significant larval mortality, particularly the extract of P. amalago var. medium; however, no extracts reduced the weight of the surviving larvae. The extract from P. amalago var. medium at the concentration of 1,011 mg L-1 caused a significant lengthening of the larval and pupal stages. The ethanolic leaf extract of P. amalago var. medium is promising for the control of T. absoluta larvae in tomato, since it exhibits acute toxicity toward these caterpillars at the concentration of 2,000 mg L-1 and affects the insect's development by reducing its survival and lengthening the larval and pupal stages.

Determination of salivary glucose in healthy adults

Objectives: Our aim in this study was to determine the concentration of salivary glucose in healthy individuals and to compare it with the capillary glycemia. Study design: Samples of unstimulated whole saliva were collected from 63 non-diabetic patients. The concentration of salivary glucose and capillary blood was measured in all of the patients. The salivary glucose was determined by enzymatic method and spectrophotometry. The data was then analyzed using the Spearman correlation test, considering values of p<0.05 to be significant. Results: The whole sample consisted of 47.6% males and 52.4% women, with an average age of 37.5±15.7 years old. The average rates of unstimulated salivary flow were 0.41±0.21 ml/min among males and 0.31±0.15 ml/min among females. No significant difference was found based on these results (p=0.078). The average blood glucose among the males studied was 100.05±13.51 mg/dL, and among females, it was 99.5±13.9 mg/dL. The average salivary glucose for the whole sample was 5.97±1.87 mg/dL, with 5.91±2.19 mg/dL among males and 5.97±1.56 mg/dL among females, respectively, without presenting any significant differences (p=0.908). The concentration of salivary glucose did not present any statistically significant correlation with the capillary glycemia (p=0.732). Conclusions: The results suggest that the concentration of salivary glucose is not dependent on capillary glycemia and that the concentration of salivary glucose does not present significant differences between the measurements for males and females.

A New Species of Sand Racer, Psammodromus (Squamata: Lacertidae), from the Western Iberian Peninsula

A new species of lacertid lizard of the genus Psammodromus is described from the Iberian Peninsula. Genetic and recently published phenotypic data support the differentiation of Psammodromus hispanicus into three, and not as previously suggested two, distinct lineages. Age estimates, lineage allopatry, the lack of mitochondrial and nuclear haplotype sharing between lineages, ecological niche divergence, and the current biogeographic distribution, indicated that the three lineages correspond to three independent species. Here, we describe a new species, Psammodromus occidentalis sp. n., which is genetically different from the other sand racers and differentiated by the number of femoral pores, number of throat scales, snout shape, head ratio, green nuptial coloration, and number of supralabial scales below the subocular scale. We also propose to upgrade the two previously recognized subspecies, Psammodromus hispanicus hispanicus Fitzinger, 1826 from central Spain and Psammodromus hispanicus edwardsianus (Dugès, 1829) from eastern Spain, to the species level: Psammodromus hispanicus stat. nov. and Psammodromus edwardsianus stat. nov. Given that the holotype of Psammodromus hispanicus was lost, we designate a neotype. We also analysed museum specimens of P. blanci, P. microdactylus and P. algirus to describe differentiation of the Psammodromus hispanicus lineages/species from their closest relatives.

Molecular analysis of a novel gene cluster encoding an insect toxin in plant-associated strains of Pseudomonas fluorescens

Pseudomonas fluorescens CHA0 and the related strain Pf-5 are well-characterized representatives of rhizosphere bacteria that have the capacity to protect crop plants from fungal root diseases, mainly by releasing a variety of exoproducts that are toxic to plant pathogenic fungi. Here, we report that the two plant-beneficial pseudomonads also exhibit potent insecticidal activity. Anti-insect activity is linked to a novel genomic locus encoding a large protein toxin termed Fit (for P. fluorescensinsecticidal toxin) that is related to the insect toxin Mcf (Makes caterpillars floppy) of the entomopathogen Photorhabdus luminescens, a mutualist of insect-invading nematodes. When injected into the haemocoel, even low doses of P. fluorescens CHA0 or Pf-5 killed larvae of the tobacco hornworm Manduca sexta and the greater wax moth Galleria mellonella. In contrast, mutants of CHA0 or Pf-5 with deletions in the Fit toxin gene were significantly less virulent to the larvae. When expressed from an inducible promoter in a non-toxic Escherichia coli host, the Fit toxin gene was sufficient to render the bacterium toxic to both insect hosts. Our findings establish the Fit gene products of P. fluorescens CHA0 and Pf-5 as potent insect toxins that define previously unappreciated anti-insect properties of these plant-colonizing bacteria

Linking genetic and species diversities in a community of freshwater gastropods

Summary Biodiversity is usually studied through species or genetic diversities. To date, these two levels of diversity have remained the independent .fields of investigations of community ecologists and population geneticists. However, recent joint analyses of species and genetic diversities have suggested that common processes may underlie the two levels. Positive correlations between species diversity and genetic diversity may arise when the effects of drift and migration overwhelm selective effects. The first goal of this thesis was to make a joint investigation of the patterns of species and genetic diversity in a community of freshwater gastropods living in a floodplain habitat. The second goal was to determine, as far as possible, the relative influences of the processes underlying the patterns observed at each level. In chapter 2 we investigate the relative influences of different evolutionary forces in shaping the genetic structure of Radix balthica populations. Results revealed that the structure inferred using quantitative traits was lower or equal to the one inferred using neutral molecular markers. Consequently, the pattern of structure observed could be only due to random drift, possibly to uniform selection, but definitely not to selection for local optima. In chapter 3, we analyze the temporal variation of species and genetic diversities in five localities. An extended period of drought occurred at the end of the study period leading to decay of both species and genetic diversities. This parallel loss of diversity following a natural perturbation highlighted the role sometimes predominant of random drift over selection on patterns of biodiversity in a floodplain habitat. In chapter 4, we compare the spatial genetic structures of two sympatric species: Radix balthica and Planorbis carinatus. We found that R. balthica populations are weakly structured and have moderate to high values of gene diversity. In contrast, P. carinatus populations are highly structured and poorly diverse. Then we measured correlations between various indices of species and genetic diversity using genetic data .from the two species. We found only one significant correlation: between species richness and gene diversity of P. carinatus. This result highlights the .need to use genetic date from more than one species to infer correlations between species and genetic diversities. Overall, this thesis provided new insights into the common processes underlying patterns of species and genetic diversity. Résumé La biodiversité est généralement étudiée au niveau de la diversité génétique ou spécifique. Ces deux niveaux sont restés jusqu'à maintenant les domaines d'investigation séparés des généticiens des populations et des écologistes des communautés. Cependant, des analyses conjointes des diversités génétique et spécifique ont récemment suggéré que des processus similaires pouvaient influencer ces deux niveaux. Des corrélations positives entre les diversités génétique et spécifique pourraient être dues aux effets de migration et de dérive qui dominent les effets sélectifs. Le premier but de cette thèse était de faire une étude conjointe des diversités génétique et spécifique dans une communauté de gastéropodes d'eau douce. Le second objectif était de déterminer les influences relatives des différents processus liés à chaque niveau de diversité. Dans le chapitre 2 nous cherchons à déterminer quelles forces évolutives influencent la structure génétique de quatre populations de Radix balthica. La structure mesurée sur des traits quantitatifs s'est révélée être plus faible ou égale à celle mesurée avec des marqueurs moléculaires neutres. La structure observée pourrait ainsi être due uniquement à la dérive génétique, potentiellement à la sélection uniforme, mais en aucun cas à la sélection locale pour différents optima. Dans le chapitre 3 nous analysons la variation temporelle des diversités génétique et spécifique dans cinq localités. Une récente période de sécheresse a causé une diminution parallèle des deux niveaux de diversité. Cette perturbation à mis en évidence le rôle parfois prépondérant de la dérive par rapport à celui de la sélection dans le déterminisme de la biodiversité dans un écosytème alluvial. Dans le chapitre 4, nous comparons la structure génétique spatiale de deux espèces vivant en sympatrie : Radix balthica et Planorbis carinatus. Les populations de R. balthica sont peu structurées et présentent un niveau de diversité relativement élevé alors que celles de P. carinatus sont fortement structurées et peu diversifiées. Nous avons ensuite mesuré différentes corrélations entre les diversités génétique et spécifique, mais la seule relation significative a été trouvée entre la richesse spécifique et la diversité génétique de P. carinatus. Ainsi, cette thèse a permis de découvrir de nouveaux aspects des processus qui influencent en parallèle la diversité aux niveaux génétique et spécifique.

Sputum containing zinc enhances carbapenem resistance, biofilm formation and virulence of Pseudomonas aeruginosa.

Pseudomonas aeruginosa chronic lung infections are the leading cause of mortality in cystic fibrosis patients, a serious problem which is notably due to the numerous P. aeruginosa virulence factors, to its ability to form biofilms and to resist the effects of most antibiotics. Production of virulence factors and biofilm formation by P. aeruginosa is highly coordinated through complex regulatory systems. We recently found that CzcRS, the zinc and cadmium-specific two-component system is not only involved in metal resistance, but also in virulence and carbapenem antibiotic resistance in P. aeruginosa. Interestingly, zinc has been shown to be enriched in the lung secretions of cystic fibrosis patients. In this study, we investigated whether zinc might favor P. aeruginosa pathogenicity using an artificial sputum medium to mimic the cystic fibrosis lung environment. Our results show that zinc supplementation triggers a dual P. aeruginosa response: (i) it exacerbates pathogenicity by a CzcRS two-component system-dependent mechanism and (ii) it stimulates biofilm formation by a CzcRS-independent mechanism. Furthermore, P. aeruginosa cells embedded in these biofilms exhibited increased resistance to carbapenems. We identified a novel Zn-sensitive regulatory circuit controlling the expression of the OprD porin and modifying the carbapenem resistance profile. Altogether our data demonstrated that zinc levels in the sputum of cystic fibrosis patients might aggravate P. aeruginosa infection. Targeting zinc levels in sputum would be a valuable strategy to curb the increasing burden of P. aeruginosa infections in cystic fibrosis patients.

A Monte Carlo approach to the inverse problem of diffuse pollution risk in agricultural catchments

The hydrological and biogeochemical processes that operate in catchments influence the ecological quality of freshwater systems through delivery of fine sediment, nutrients and organic matter. Most models that seek to characterise the delivery of diffuse pollutants from land to water are reductionist. The multitude of processes that are parameterised in such models to ensure generic applicability make them complex and difficult to test on available data. Here, we outline an alternative - data-driven - inverse approach. We apply SCIMAP, a parsimonious risk based model that has an explicit treatment of hydrological connectivity. we take a Bayesian approach to the inverse problem of determining the risk that must be assigned to different land uses in a catchment in order to explain the spatial patterns of measured in-stream nutrient concentrations. We apply the model to identify the key sources of nitrogen (N) and phosphorus (P) diffuse pollution risk in eleven UK catchments covering a range of landscapes. The model results show that: 1) some land use generates a consistently high or low risk of diffuse nutrient pollution; but 2) the risks associated with different land uses vary both between catchments and between nutrients; and 3) that the dominant sources of P and N risk in the catchment are often a function of the spatial configuration of land uses. Taken on a case-by-case basis, this type of inverse approach may be used to help prioritise the focus of interventions to reduce diffuse pollution risk for freshwater ecosystems. (C) 2012 Elsevier B.V. All rights reserved.

Divergent and narrower climatic niches characterize polyploid species of European primroses in Primula sect. Aleuritia

Aim It is hypothesized that the ecological niches of polyploids should be both distinct and broader than those of diploids - characteristics that might have allowed the successful colonization of open habitats by polyploids during the Pleistocene glacial cycles. Here, we test these hypotheses by quantifying and comparing the ecological niches and niche breadths of a group of European primroses. Location Europe. Methods We gathered georeferenced data of four related species in Primula sect. Aleuritia at different ploidy levels (diploid, tetraploid, hexaploid and octoploid) and used seven bioclimatic variables to quantify niche overlap between species by applying a series of univariate and multivariate analyses combined with modelling techniques. We also employed permutation-based tests to evaluate niche similarity between the four species. Niche breadth for each species was evaluated both in the multivariate environmental space and in geographical space. Results The four species differed significantly from each other in mono-dimensional comparisons of climatological variables and occupied distinct habitats in the multi-dimensional environmental space. The majority of the permutation-based tests either indicated that the four species differed significantly in their habitat preferences and ecological niches or did not support significant niche similarity. Furthermore, our results revealed narrower niche breadths and geographical ranges in species of P. sect. Aleuritia at higher ploidy levels. Main conclusions The detected ecological differentiation between the four species of P. sect. Aleuritia at different ploidy levels is consistent with the hypothesis that polyploids occupy distinct ecological niches that differ from those of their diploid relative. Contrary to expectations, we find that polyploid species of P. sect. Aleuritia occupy narrower environmental and geographical spaces than their diploid relative. These results on the ecological niches of closely related polyploid and diploid species highlight factors that potentially contribute to the evolution and distribution of polyploid species.

Investigation phytochimique des plantes aquatiques Potamogeton pectinatus L., P. lucens L., P. perfoliatus L. et P. crispus L. (Potamogetonaceae)

Dans le cadre de la recherche de nouveaux composés naturels, les métabolites secondaires de plantes aquatiques indigènes, les potamots Potamogeton pectinatus L., P. lucens L., P. perfoliatus L. et P. crispus L. (Potamogetonaceae), ont été étudiés. Par leur position écologique et évolutive particulière entre environnement terrestre et aquatique, les plantes aquatiques ou macrophytes pourraient en effet avoir sélectionné des composés avec des caractéristiques originales. Les extraits dichlorométhaniques (apolaires) des potamots ont été analysés par HPLCUV, HPLC-MS, HPLC-RMN et GC-MS, et testés contre diverses cibles biologiques. Sur la base de ces résultats, les extraits apolaires de P. pectinatus et P. lucens ont été étudiés de manière plus approfondie. Ils ont été fractionnés sur des colonnes ouvertes et par VLC, LPLC, MPLC, CPC et HPLC semi-préparative. Une partie de leurs constituants ont été isolés et leurs structures déterminées par des méthodes spectroscopiques, en particulier par RMN et par MS. Quinze composés ont été ainsi isolés de P. pectinatus et P. lucens, dont sept sont des nouveaux produits naturels. Parmi ces quinze produits, neuf sont des diterpènes ent-labdanes contenant un noyau furane ou un groupe lactonique, dont six sont décrits ici pour la première fois. Certains de ces diterpènes ont montré une activité algicide, ce qui indique une de leurs fonctions possible dans les potamots, et un de ces labdanes, le méthyl-15,16-époxy-12-oxo-8(17),13(16),14-ent-labatrièn-19-oate, a également des propriétés anti-inflammatoires. Les composés présents dans les extraits méthanoliques (polaires) n?ont pas été isolés, mais quatorze d?entre eux ont pu être identifiés par HPLC-UV, HPLC-MS et HPLCRMN. Une majorité de ces constituants sont des flavonoïdes connus, des dérivés glycosylés de l?apigénine, la lutéoline et le chrysoériol, également présents en tant qu?aglycones. Plusieurs ent-labdanes glycosylés ont pu être également identifiés dans ces extraits, parmi lesquels un nouveau composé dont la structure a pu être partiellement déterminée. En conclusion, ce travail a permis de mieux connaître la phytochimie de plusieurs plantes aquatiques de Suisse, et d?isoler de nouveaux produits naturels avec des propriétés biologiques et pharmacologiques intéressantes.<br/><br/>The secondary metabolites of Swiss freshwater plants, the pondweeds Potamogeton pectinatus L., P. lucens L., P. perfoliatus L. and P. crispus L. (Potamogetonaceae), were investigated. Because of their peculiar habitat, in-between aquatic and terrestrial life, aquatic plants should produce secondary metabolites with original chemical or biological features. Their apolar extracts were analysed by HPLC-UV, HPLC-MS, HPLC-NMR and GCMS, and were tested with different bioassays. Based on these results, the apolar extracts of P. pectinatus and P. lucens were investigated more extensively. They were fractionated on open columns, and by VLC, LPLC, MPLC, CPC and semi-preparative HPLC. Their constituents were isolated and their structures elucidated by spectroscopic methods as MS and NMR. Fifteen compounds could be isolated from P. pectinatus and P. lucens, and seven were new natural products. Nine of them were ent-labdane diterpenes with a furan moiety or a lactone group, and six of these labdanes were reported here for the first time as natural products. Some of these diterpenes showed an algaecide effect. This activity indicated their potential ecological function in pondweeds. One compound, methyl-15,16-epoxy-12-oxo-8(17),13(16),14-ent-labatrien-19-oate, revealed also some anti-inflammatory properties. The constituents of polar extracts were not isolated, but fourteen of them could be identified by HPLC-UV, HPLC-MS and HPLC-NMR. The major part of these compounds was known flavonoids as apigenin, lutolin, chrysoeriol and their glycosylated derivatives. Several glycosylated ent-labdanes were also identified, and the structure of a new labdane dihexoside was partially elucidated. In conclusion this study allowed a better knowledge of the phytochemistry of Swiss aquatic plants, and the isolation of new natural products with interesting biological and pharmacological properties.

Investigation of interaction between native and impurity defects in ZnSe

Zinc selenide is a prospective material for optoelectronics. The fabrication of ZnSe­based light-emitting diodes is hindered by complexity of p-type doping of the component materials. The interaction between native and impurity defects, the tendency of doping impurity to form associative centres with native defects and the tendency to self-compensation are the main factors impeding effective control of the value and type of conductivity. The thesis is devoted to the study of the processes of interaction between native and impurity defects in zinc selenide. It is established that the Au impurity has the most prominent amphoteric properties in ZnSe among Cu, Ag and Au impurities, as it forms a great number of both Au; donors and Auz„ acceptors. Electrical measurements show that Ag and Au ions introduced into vacant sites of the Zn sublattice form simple single-charged Agz„+ and Auzn+ states with d1° electron configuration, while Cu ions can form both single-charged Cuz„ (d1) and double-charged Cuzr`+ (d`o) centres. Amphoteric properties of Ag and Au transition metals stimulated by time are found for the first time from both electrical and luminescent measurements. A model that explains the changes in electrical and luminescent parameters by displacement of Ag ions into interstitial sites due to lattice deformation forces is proposed. Formation of an Ag;-donor impurity band in ZnSe samples doped with Ag and stored at room temperature is also studied. Thus, the properties of the doped samples are modified due to large lattice relaxation during aging. This fact should be taken into account in optoelectronic applications of doped ZnSe and related compounds.

A germination study of herbicide-resistant field poppies in Spain

Field poppy, Papaver rhoeas L., is a very common weed in winter cereals in North-Eastern Spain. Its control is becoming difficult due to expanding herbicide resistance. To control field poppies there are alternative strategies such as non-chemical control that take into account the weed emergence period. However, there is a lack of knowledge of P. rhoeas emergence patterns in semi-arid conditions. Thus, here we conducted pot experiments on the emergence of P. rhoeas. We aimed to describe the emergence period and to quantify the emergence of a susceptible and of a herbicide-resistant P. rhoeas population at two locations in Catalonia, Spain, from 1998 to 2001 and until 2004 at one of them. Therefore, pots containing seeds of both populations were established at the two locations and emergence was recorded monthly. We studied the origin of the population, the sowing location, the effect of cultivation and the sowing year. First, we found that the main emergence peaks in our experiments occurred in autumn, accounting for between 65.7 and 98.5% of the annual emergence from October to December, and only little emergence was recorded in spring. This emergence pattern is different from those found in the literature corresponding to Northern European countries, where in some cases main flushes occur only in autumn, in spring and winter or only in spring. The emergence was mainly affected by cultivation, but the effect of light stimulus was observed several months later. As a consequence, cultivation should be done in early autumn, promoting emergence during the whole autumn and winter so that emerged seedlings can be controlled before sowing a spring crop. Second, most experiments showed that the emergence was significantly higher in the first autumn than in the following seasons, e.g. 4.1% emergence in the first year and only 2.1, 2.3, 0.5 and 0.6% new emergence at one of the locations for the second, third, fourth and fifth years. Thus, after having a severe P. rhoeas infestation causing a big seed rain, emergence should be stimulated by autumn cultivation in the following season and seedlings controlled by trying to deplete the soil seed bank as much as possible. Despite the fact that emergence will be staggered throughout several years and that there was a significant relationship between rainfall and emergence, so that dry years will cause a smaller emergence rate of the weed, these findings define a cultural management strategy to reduce P. rhoeas infestations and to contribute to integrated weed management strategies combining it with other tools.

Epithelial sodium transport and its control by aldosterone: the story of our internal environment revisited.

Transcription and translation require a high concentration of potassium across the entire tree of life. The conservation of a high intracellular potassium was an absolute requirement for the evolution of life on Earth. This was achieved by the interplay of P- and V-ATPases that can set up electrochemical gradients across the cell membrane, an energetically costly process requiring the synthesis of ATP by F-ATPases. In animals, the control of an extracellular compartment was achieved by the emergence of multicellular organisms able to produce tight epithelial barriers creating a stable extracellular milieu. Finally, the adaptation to a terrestrian environment was achieved by the evolution of distinct regulatory pathways allowing salt and water conservation. In this review we emphasize the critical and dual role of Na(+)-K(+)-ATPase in the control of the ionic composition of the extracellular fluid and the renin-angiotensin-aldosterone system (RAAS) in salt and water conservation in vertebrates. The action of aldosterone on transepithelial sodium transport by activation of the epithelial sodium channel (ENaC) at the apical membrane and that of Na(+)-K(+)-ATPase at the basolateral membrane may have evolved in lungfish before the emergence of tetrapods. Finally, we discuss the implication of RAAS in the origin of the present pandemia of hypertension and its associated cardiovascular diseases.