Effect of temperature and starvation upon survival strategies of Pseudomonas fluorescens CHA0: comparison with Escherichia coli

Microorganisms in aquatic systems are exposed to continuous modifications in their environmental conditions. In these systems, both autochthonous and allochthonous bacteria respond to adverse conditions by expressing viable but nonculturable phenotype. On the basis of this common response, the behaviour of a few species is extrapolated to others. We compared the survival strategies of Escherichia coli (allochthonous, mesophile bacterium) and Pseudomonas fluorescens CHA0 (ubiquitous, psychrotrophic bacteria) under nonoptimal temperature and nutrient deprivation. In the absence of nutrients, the effect of temperature on the loss of culturability did not show a common pattern. Whereas the survival of E. coli had an inverse relationship with temperature, whereas for P. fluorescens a direct relationship between temperature and T?? values was only established in the range 5-15°C, with an inverse relationship at higher temperatures. When the subproteome of the outer membrane of P. fluorescens was comparatively analysed, starvation was not the main source of change. The most relevant modifications were due to variations in temperature. OprF, the major surface protein of the genus Pseudomonas, showed a high expression in nonculturable as well as culturable populations under all the adverse situations analysed. We therefore propose OprF as a suitable marker for Pseudomonas detection in the environment.     

Epigenetic activation of SOX11 in lymphoid neoplasms by histone modifications

Recent studies have shown aberrant expression of SOX11 in various types of aggressive B-cell neoplasms. To elucidate the molecular mechanisms leading to such deregulation, we performed a comprehensive SOX11 gene expression and epigenetic study in stem cells, normal hematopoietic cells and different lymphoid neoplasms. We observed that SOX11 expression is associated with unmethylated DNA and presence of activating histone marks (H3K9/14Ac and H3K4me3) in embryonic stem cells and some aggressive B-cell neoplasms. In contrast, adult stem cells, normal hematopoietic cells and other lymphoid neoplasms do not express SOX11. Such repression was associated with silencing histone marks H3K9me2 and H3K27me3. The SOX11 promoter of non-malignant cells was consistently unmethylated whereas lymphoid neoplasms with silenced SOX11 tended to acquire DNA hypermethylation. SOX11 silencing in cell lines was reversed by the histone deacetylase inhibitor SAHA but not by the DNA methyltransferase inhibitor AZA. These data indicate that, although DNA hypermethylation of SOX11 is frequent in lymphoid neoplasms, it seems to be functionally inert, as SOX11 is already silenced in the hematopoietic system. In contrast, the pathogenic role of SOX11 is associated with its de novo expression in some aggressive lymphoid malignancies, which is mediated by a shift from inactivating to activating histone modifications.     

The Ras/MAPK pathway is required for generation of iNKT cells

iNKT cells derive from CD4(+)CD8(+) DP thymocytes, and are selected by thymocyte-thymocyte interactions through signals from their invariant Vα14-Jα18 TCR and from the costimulatory molecules SLAMF1 and SLAMF6. Genetic studies have demonstrated the contribution of different signaling pathways to this process. Surprisingly, current models imply that the Ras/MAPK pathway, one of the critical mediators of conventional αβ T cell positive selection, is not necessary for iNKT cell development. Using mice defective at different levels of this pathway our results refute this paradigm, and demonstrate that Ras, and its downstream effectors Egr-1 and Egr-2 are required for positive selection of iNKT cells. Interestingly our results also show that there are differences in the contributions of several of these molecules to the development of iNKT and conventional αβ T cells.     

The lymphocyte receptor CD6 interacts with syntenin-1, a scaffolding protein containing PDZ domains

CD6 is a type I membrane glycoprotein expressed on thymocytes, mature T and B1a lymphocytes, and CNS cells. CD6 binds to activated leukocyte cell adhesion molecule (CD166), and is considered as a costimulatory molecule involved in lymphocyte activation and thymocyte development. Accordingly, CD6 partially associates with the TCR/CD3 complex and colocalizes with it at the center of the mature immunological synapse (IS) on T lymphocytes. However, the signaling pathway used by CD6 is still mostly unknown. The yeast two-hybrid system has allowed us the identification of syntenin-1 as an interacting protein with the cytoplasmic tail of CD6. Syntenin-1 is a PDZ (postsynaptic density protein-95, postsynaptic discs large, and zona occludens-1) domain-containing protein, which functions as an adaptor protein able to bind cytoskeletal proteins and signal transduction effectors. Mutational analyses showed that certain amino acids of the most C-terminal sequence of CD6 (-YDDISAA) and the two postsynaptic density protein-95, postsynaptic discs large, and zona occludens-1 domains of syntenin-1 are relevant to the interaction. Further confirmation of the CD6-syntenin-1 interaction was obtained from pull-down and co-immunoprecipitation assays in mammalian cells. Image analyses also showed that syntenin-1 accumulates at CD6 caps and at the IS. Therefore, we propose that syntenin-1 may function as a scaffolding protein coupling CD6 and most likely other lymphocyte receptors to cytoskeleton and/or signaling effectors during IS maturation.     

Antioxidant and antimicrobial properties of ethanolic extract fromLepista nuda (Bull.) Cooke

Antioxidant capacity and antimicrobial activities ofLepista nuda (Bull.) Cooke extracts obtained with ethanol were investigated. Four complementary test systems, namely DPPH free radical scavenging, β-carotene/linoleic acid systems, total phenolic compounds and total flavonoid concentration, have been used. Linoleic, acid inhibition values ofL. nuda ethanolic extract, BHA and α-to copherol standards were found to be 84.3% 98.9% and 99.2% respectively in the concentration of 160μg/ml. Total flavonoid amount was 8.21 ± 0.56 μg mg^?1 quercetin equivalent while the phenolic compound amount was 48.01 ± 0.29 μg mg^?1 pyrocatechol equivalent in the extract. The antimicrobial activity ofL. nuda extract was testedin vitro by using the agar-well diffusion method. TheL. nuda extract showed antibacterial activity againstMicrococcus flavus, Micrococcus luteus, Bacillus cereus, Yersinia enterocolitica, Staphylococcus aureus, Salmonella enteritidis andEscherichia coli. TheL. nuda extract did not exhibit antican didal activity againstCandida albicans. The extracts could be suitable as antimicrobial and antioxidativeagents in the food industry.     

Foliar application of urea to “Sauvignon Blanc” and “Merlot” vines: doses and time of application

A careful control of the N nutritional status of grapevines can have a determining effect on wine characteristics; therefore a suitable management of N fertilization might allow some wine parameters to be modified, thereby improving product quality. The aim of this study was to determine the effect of foliar application of urea at different doses and different times of the growing season on the parameters of Sauvignon Blanc and Merlot grape juice. The research described herein involved Sauvignon Blanc and Merlot grapevines (V. vinifera L.) at a commercial vineyard and was conducted over 2 years. In the first year, N treatment involved a foliar application at a dose of 10 kg N ha^?1 during veraison, whereas in the second year it involved a foliar urea application at two doses (10 and 50 kg N ha^?1) and at three different times—3 weeks before veraison, during veraison and 3 weeks after veraison. In this second year, the urea applied at a dose of 10 kg N ha^?1 was isotopically labelled with 1% ¹⁵N. Chemical parameters, yeast assimilable N, amino acid content, amino acid profile and N isotopic composition were determined for all treatments. Grape and grape-juice parameters for Merlot were found to be more affected by N fertilization than for Sauvignon Blanc and were also more affected during the second year than during the first year, thus indicating that the climatic characteristics of each campaign could affect these parameters. The yeast assimilable N in grape juice was found to be higher for late applications of foliar urea, with application of the higher dose of urea during veraison increasing the amino acid and proline contents in both varieties. The isotopic analysis data showed that the urea applied to leaves was transferred to the berries, with the maximum translocation in Sauvignon Blanc occurring for the post-veraison treatment and in Merlot for the veraison treatment. We can therefore conclude that foliar application of urea could modify grape juice quality and could therefore be used as a tool for obtaining quality wines.     

The physiological implications of urease inhibitors on N metabolism during germination of Pisum sativum and Spinacea oleracea seeds

The development of new nitrogen fertilizers is necessary to optimize crop production whilst improving the environmental aspects arising from the use of nitrogenous fertilization as a cultural practice. The use of urease inhibitors aims to improve the efficiency of urea as a nitrogen fertilizer by preventing its loss from the soil as ammonia. However, although the action of urease inhibitors is aimed at the urease activity in soil, their availability for the plant may affect its urease activity. The aim of this work was therefore to evaluate the effect of two urease inhibitors, namely acetohydroxamic acid (AHA) and N-(n-butyl) thiophosphoric triamide (NBPT), on the germination of pea and spinach seeds. The results obtained show that urease inhibitors do not affect the germination process to any significant degree, with the only process affected being imbibition in spinach, thus also suggesting different urease activities for both plants. Our findings therefore suggest an activity other than the previously reported urolytic activity for urease in spinach. Furthermore, of the two inhibitors tested, NBPT was found to be the most effective at inhibiting urease activity, especially in pea seedlings.     

Differences between Neandertal and modern human infant and child growth models

Studying the emergence of distinctive human growth patterns is essential to understanding the evolution of our species. The large number of Neandertal fossils makes this species the best candidate for a comparative study of growth patterns in archaic and modern humans. Here, Neandertal height growth during infancy and early childhood is described using a mathematical model. Height growth velocities for individuals five years old or younger are modelled as age functions based on different estimates of height and age for a set of ten Neandertal infants and children. The estimated heights of each Neandertal individual are compared with those of two modern human populations based on longitudinal and cross-sectional data. The model highlights differences in growth velocity during infancy (from the age of five months onward). We find that statural growth in Neandertal infants is much slower than that seen in modern humans, Neandertal growth is similar to modern humans at birth, but decreases around the third or fourth month. The markedly slower growth rates of Neandertal infants may be attributable to ontogenetic constraints or to metabolic stress, and contribute to short achieved adult stature relative to modern humans.     

A model for small‐scale seed bank and standing vegetation connection along time

Since inter‐annual climatic variability influences composition and structure of seed bank and extant vegetation, it is expected that it also affects the relationship between both compartments at small scales along time. We hypothesize that seed bank and aboveground vegetation are closely and sequentially linked at small spatial and time scales. We conducted a field spatially explicit investigation to explore the spatial and temporal relationship between both compartments. Abundance, composition and spatial structure at different small‐scales of seed bank and aboveground vegetation were analysed through 100 permanent plots during two consecutive (dry and wet) periods of growth. Following a conceptual transition path model, we analysed changes in correlation values in composition and spatial aggregation between both compartments along time including seasonal variations of seed bank. Shape of spatial structures were evaluated using partial Mantel correlograms. Annuals and perennials guilds were studied separately. During the wet year, annuals increased their aerial spatial aggregation and cover, whereas the opposite happened for perennials. Density and spatial aggregation of the seed bank increased for both guilds in the two seasons following the rain period, especially in annuals. The clumped structure of the transient seed bank is a consequence of the addition of spatial structure of extant vegetation and the persistent seed bank. Expression of the persistent seed bank is much lower during the dry period for the annual guild. In spite of the strong yearly variability, the community maintained a highly structured spatiotemporal pattern. The mechanisms promoting this stability differed for annual and perennial guilds. Temporal persistence in perennials relied mainly in established plants longevity, whereas annual guild persistence depended solely on seed bank. This tight structure was coherent with the existence of successional dynamics in the community, although persistent seed bank could moderate the pace. Longer term studies of seed bank–standing vegetation dynamics are required to fully understand this process.