Biomass changes and bentho-pelagic transfers throughout the Benthic Boundary Layer in the English Channel

One hundred and eight suprabenthic hauls were taken from sixsites in the English Channel with a modified Macer-GIROQ sledgethat permitted the sampling of three kinds of organisms in thebenthic boundary layer: mesozooplankton, macrozooplankton andsuprabenthos. A complete annual cycle was sampled in the Bayof Saint-Brieuc but only spring and autumn samplings were takenfrom the other sites. Meso- and macrozooplankton biomasses wereusually higher at every site during the daytime than at night;in contrast, suprabenthic biomasses were lower during the daythan at night. However, at site 5, on pebble substrates, everyfaunistic group showed a higher biomass during the day thanat night, while at site 2 the opposite occurred. Meso- and macrozooplanktonbiomasses were at their maximum during spring whereas the highestbiomass of suprabenthos was observed from summer to autumn.Daytime exchanges were by mesozooplanktonic organisms and night-timeexchanges were by suprabenthic species, especially amphipods,mysids and large decapods. Daily transfers showed the same patternfor every faunistic group, and transfers were higher in autumnthan in spring, except at site 1 where it was similar duringboth seasons. Three groups of sites were identified from theirannual transfers: sites 1 and 3, on the Brittany coasts, withlowest annual transfers; site 2, offshorePlymouth, with thehighest transfer, and the three eastern sites (4, 5 and 6) showingsimilar annual transfers. The rate between macrobenthic productionand annual transfers was high at coarse sand and pebble siteswhere the benthic macrofauna was endobenthic and sessile, suggestinga concentration of carbon in the bottom. On the other hand,this rate was low on medium sand substrates where the benthicmacrofauna was vagile, suggesting that carbon remained concentratedin the benthic boundary layer where exchanges were most importantby the migration of both pelagic and benthic organisms in thiscompartment.     

Effect of chitin waste-based composts produced by two-phase composting on two oomycete plant pathogens

Biphasic composts were prepared by first mixing peat moss and sawdust with a nitrogen-rich biomass such as chitinous waste or cow manure and composting them until termination of the thermophilic phase. These partially stabilized composts were then amended with shrimp waste inducing a second thermophilic phase. Filter-sterilized water extracts obtained from two mature biphasic composts (SP₂W₂+S and MPW+S) reduced the growth of two oomycete plant pathogens, Phytophthora fragariae var. rubi and Pythium ultimum. Both SP₂W₂+S and MPW+S composts significantly reduce the incidence of cucumber damping-off caused by Pythium ultimum as compared to a commercial brand of compost made from shrimp waste and peat moss. Hydrolysis products of chitin were unlikely to be responsible for growth inhibition since no oligomeric forms of chitin were detected in SP₂W₂+S. The shrimp waste amendment carried out after the first thermophilic phase modified the microbial populations of biphasic composts. Following the amendment, the proportion of branched-chain microbial fatty acids typical of Gram-positive bacteria increased considerably suggesting that this group of bacteria became more prevalent within the total microbial population. These data suggests that the two-phase composting process promotes the proliferation of Gram-positive bacteria antagonistic to oomycete plant pathogens.     

Effects of a fraction from maize root exudates on haploid strains of Sporisorium reilianum f. sp. zeae

Sporisorium reilianum f. sp. zeae is the causal agent of head smut of maize. Although the main symptom of this disease is the formation of a black fungal sorus on the reproductive parts of the maize, the infection always occurs via the roots. Early infection stages are characterised by a hyphal proliferation of the fungus around the roots. In this paper, we describe effects of a fraction extracted from maize root exudates on growth of S. reilianum f. sp. zeae. The fungus grew as a yeast form on artificial medium, but in presence of these fractions, some yeasts switched to a hyphal form. In addition, an increased proliferation of the yeast form was also observed with exudates from a variety of maize susceptible to head smut. In the presence of exudates obtained from a tolerant variety of maize, proliferation of the yeast form was inhibited, whereas the induction of yeast-hypha transition was always observed. These results indicated that some molecules in root exudates could play a role in the pre-infectious stage between maize and S. reilianum f. sp. zeae.     

High endemicity of Q fever in French Guiana: A cross sectional study (2007–2017)

Q fever (QF) is a zoonosis caused by Coxiella burnetii (Cb). French Guiana (FG) had a high incidence but no data have been published since 2006. The objective of this study was to update the incidence and epidemiological data on QF in FG. A retrospective study of all FG Q fever serodiagnosis between 2007 and 2017 was carried out. Among the 695 patients included, the M/F sex-ratio was 2.0 and the median age of 45.3 years (IQR 33.7–56.3). The annual QF incidence rate was 27.4 cases (95%CI: 7.1–47.7) per 100,000 inhabitants ranging from 5.2 in 2007 to 40.4 in 2010. Risk factors associated with Q fever compared to general population were male gender, being born in mainland France, an age between 30 to 59 years-old and a residence in Cayenne and surroundings. The incidence of QF in FG remains high and stable and the highest in the world.     

PHYSIOLOGICAL RESPONSES TO TEMPERATURE AND IRRADIANCE IN SPIROGYRA (ZYGNEMATALES, CHAROPHYCEAE)1

Spirogyra Link (1820) is an anabranched filamentous green alga that forms free-floating mats in shallow waters. It occurs widely in static waters such as ponds and ditches, sheltered littoral areas of lakes, and stow-flowing streams. Field observations of its seasonal distribution suggest that the 70-μm-wide filament form of Spirogyra should have a cool temperature and high irradiance optimum for net photosynthesis. Measurements of net photosynthesis and respiration were marie at 58 combinations of tight and temperature in a controlled environment facility. Optimum conditions were 25°C and 1500 μmol photons m⁻² s⁻¹, at which net photosynthesis averaged 75.7 mg O₂ gdm⁻¹ h⁻¹. Net photosynthesis was positive at temperatures from 5° to 35°C at most irradiances except at combinations of extremely low irradiances and high temperatures (7 and 23 μmol photons m⁻² s⁻¹ at 30°C and 7, 23, and 35 μmol photons m⁻² s⁻¹ at 35°C). Respiration rates increased with both temperature and prior irradiance. Light-enhanced respiration rates were significantly greater than dark respiration rates following irradiances of 750 μmol photons m⁻² s⁻¹ or greater. Polynomials were fitted to the data to generate response surfaces; such response surfaces can be used to represent net photosynthesis and respiration in ecological models. The data indicate that the alga can tolerate the cool water and high irradiances characteristic of early spring but cannot maintain positive net photosynthesis under conditions of high temperature and low light (e.g. when exposed to self-shading ).     

Individual variation in migratory and exploratory movements and habitat use by adult red deer (<Emphasis Type="Italic">Cervus elaphus</Emphasis> L.) in a mountainous temperate forest

Using data from a global positioning system (GPS), seven adult red deer (Cervus elaphus L.) were tracked in the Parc National des Cévennes, southern France, between November 1998 and December 2000 to assess the factors affecting large-range movement patterns and habitat use. The home range varied from a single compact area for females to three distinct seasonal ranges for males, which used alternative migratory strategies (i.e. non-, downward- and upward-migrants). The migrants used mainly southerly and easterly aspects, and wintered in areas having steeper slopes than were used during summer or the rut season. For males, the time of rut migration was mid-September and they finally entered wintering ranges from mid-December to the beginning of January. Exploratory behaviour (i.e. individuals found outside the limits of their familiar area but returning to it a few days later) occurred in both sexes and for all individuals monitored during at least a 6-month period. Velocity and efficiency of exploratory movements were higher than usual movements. During these exploratory movements, hinds may have used different landscape attributes (elevation, slope, canopy cover) while stags did not. These results provide new empirical information that could be used for building and applying broad-scale spatial and landscape use models in ecological research.     

Tyrosine-sulfate isosteres of CCR5 N-terminus as tools for studying HIV-1 entry

The HIV-1 co-receptor CCR5 possesses sulfo-tyrosine (TYS) residues at its N-terminus (Nt) that are required for binding HIV-1 gp120 and mediating viral entry. By using a 14-residue fragment of CCR5 Nt containing two TYS residues, we recently showed that CCR5 Nt binds gp120 through a conserved region specific for TYS moieties and suggested that this site may represent a target for inhibitors and probes of HIV-1 entry. As peptides containing sulfo-tyrosines are difficult to synthesize and handle due to limited stability of the sulfo-ester moiety, we have now incorporated TYS isosteres into CCR5 Nt analogs and assessed their binding to a complex of gp120-CD4 using saturation transfer difference (STD) NMR and surface plasmon resonance (SPR). STD enhancements for CCR5 Nt peptides containing tyrosine sulfonate (TYSN) in complex with gp120-CD4 were very similar to those observed for sulfated CCR5 Nt peptides indicating comparable modes of binding. STD enhancements for phosphotyrosine-containing CCR5 Nt analogs were greatly diminished consistent with earlier findings showing sulfo-tyrosine to be essential for CCR5 Nt binding to gp120. Tyrosine sulfonate-containing CCR5 peptides exhibited reduced water solubility, limiting their use in assay and probe development. To improve solubility, we designed, synthesized, and incorporated in CCR5 Nt peptide analogs an orthogonally functionalized azido tris(ethylenoxy) l-alanine (l-ate-Ala) residue. Through NMR and SPR experiments, we show a 19-residue TYSN-containing peptide to be a functional, hydrolytically stable CCR5 Nt isostere that was in turn used to develop both SPR-based and ELISA assays to screen for inhibitors of CCR5 binding to gp120-CD4.     

In vivo gamma-tocopherol supplementation decreases systemic oxidative stress and cytokine responses of human monocytes in normal and asthmatic subjects

We have recently reported that gamma-tocopherol (gammaT) reduces allergen- and zymosan-induced inflammation using rodent models. As an initial step in extending these observations to humans, we conducted an open-label, Phase I dosing study of two doses (one or two capsules daily for 1 week) of a gamma-tocopherol-rich preparation containing 623 mg of gamma-tocopherol, 61.1 mg of d-alpha-tocopherol, 11.1 mg of d-beta-tocopherol (11.1 mg), and 231 mg of d-sigma-tocopherol per capsule. Endpoints for this study include serum levels of 5-nitro-gamma-tocopherol, as a marker of oxidative stress, and changes in serum gamma-, alpha-, and delta-tocopherol and gamma-2'-carboxyethyl-6-hydroxychroman (CEHC) 6 and 24 h after the first dose and after 1 week of treatment. To assess the biological activity of this treatment, we obtained peripheral blood mononuclear cells at baseline and after 1 week of treatment with two capsules of a gamma-tocopherol-rich preparation/day and examined the inflammatory cytokine response of these cells in culture to ex vivo endotoxin/LPS (0.01 ng/ml) challenge. We also monitored a number of safety endpoints to examine how well this preparation is tolerated in eight normal volunteers (four allergic and four nonallergic) and eight allergic asthmatics. We further obtained human monocytes from a subset of these volunteers and treated them ex vivo with gammaT, alphaT, gamma-CEHC, and alpha-CEHC and assessed their actions on LPS-induced degradation of IkappaBalpha and JNK signaling and ROS generation. As detailed herein, this open-label study demonstrates that gamma-tocopherol-enriched supplementation decreased systemic oxidative stress, increased serum levels of gamma-tocopherol, and inhibited monocyte responses to LPS without any adverse health effects. Further, in vitro treatment of human monocytes with gamma-CEHC and alpha-CEHC inhibits ROS generation and LPS-induced degradation of IkappaB and JNK activation.     

Prion Fibrils of Ure2p Assembled under Physiological Conditions Contain Highly Ordered, Natively Folded Modules

The difference between the prion and the non-prion form of a protein is given solely by its three-dimensional structure, according to the prion hypothesis. It has been shown that solid-state NMR can unravel the atomic-resolution three-dimensional structure of prion fragments but, in the case of Ure2p, no highly resolved spectra are obtained from the isolated prion domain. Here, we demonstrate that the spectra of full-length fibrils of Ure2p interestingly lead to highly resolved solid-state NMR spectra. Prion fibrils formed under physiological conditions are therefore well-ordered objects on the molecular level. Comparing the full-length NMR spectra with the corresponding spectra of the prion and globular domains in isolation reveals that the globular part in particular shows almost perfect structural order. The NMR linewidths in these spectra are as narrow as the ones observed in crystals of the isolated globular domain. For the prion domain, the spectra reflect partial disorder, suggesting structural heterogeneity, both in isolation and in full-length Ure2p fibrils, although to different extents. The spectral quality is surprising in the light of existing structural models for Ure2p and in comparison to the corresponding spectra of the only other full-length prion fibrils (HET-s) investigated so far. This opens the exciting perspective of an atomic-resolution structure determination of the fibrillar form of a prion whose assembly is not accompanied by significant conformational changes and documents the structural diversity underlying prion propagation.