Effects of bioaerosol exposure on work-related symptoms among Swiss sawmill workers

Objective: Exposure to bioaerosols in the occupational environment of sawmills could be associated with a wide range of health effects, in particular respiratory impairment, allergy and organic dust toxic syndrome. The objective of the study was to assess the frequency of medical respiratory and general symptoms and their relation to bioaerosol exposure. Method: Twelve sawmills in the French part of Switzerland were investigated and the relationship between levels of bioaerosols (wood dust, airborne bacteria, airborne fungi and endotoxins), medical symptoms and impaired lung function was explored. A health questionnaire was distributed to 111 sawmill workers. Results: The concentration of airborne fungi exceeded the limit recommended by the Swiss National Insurance (SUVA) in the twelve sawmills. This elevated fungi level significantly influenced the occurrence of bronchial syndrome (defined by cough and expectorations). No other health effects (irritations or respiratory effects) could be associated to the measured exposures. We observed that junior workers showed significantly more irritation syndrome (defined by itching/running nose, snoring and itching/red eyes) than senior workers. Lung function tests were not influenced by bioaerosol levels nor dust exposure levels. Conclusion: Results suggest that occupational exposure to wood dust in a Swiss sawmill does not promote a clinically relevant decline in lung function. However, the occurrence of bronchial syndrome is strongly influenced by airborne fungi level

Diffraction microtomography with sample rotation: influence of a missing apple core in the recorded frequency space

Diffraction microtomography in coherent light is foreseen as a promising technique to image transparent living samples in three dimensions without staining. Contrary to conventional microscopy with incoherent light, which gives morphological information only, diffraction microtomography makes it possible to obtain the complex optical refractive index of the observed sample by mapping a three-dimensional support in the spatial frequency domain. The technique can be implemented in two configurations, namely, by varying the sample illumination with a fixed sample or by rotating the sample using a fixed illumination. In the literature, only the former method was described in detail. In this report, we precisely derive the three-dimensional frequency support that can be mapped by the sample rotation configuration. We found that, within the first-order Born approximation, the volume of the frequency domain that can be mapped exhibits a missing part, the shape of which resembles that of an apple core. The projection of the diffracted waves in the frequency space onto the set of sphere caps covered by the sample rotation does not allow for a complete mapping of the frequency along the axis of rotation due to the finite radius of the sphere caps. We present simulations of the effects of this missing information on the reconstruction of ideal objects.Comment: 7 pages, 11 figures, presented at Focus On Microscopy 200

Paenibacillus melissococcoides sp. nov., isolated from a honey bee colony affected by European foulbrood disease.

A novel, facultatively anaerobic, Gram-stain-positive, motile, endospore-forming bacterium of the genus Paenibacillus, designated strain 2.1T, was isolated from a colony of Apis mellifera affected by European foulbrood disease in Switzerland. The rod-shaped cells of strain 2.1T were 2.2–6.5 μm long and 0.7–1.1 μm wide. Colonies of strain 2.1T were orange-pigmented under oxic growth conditions on solid basal medium at 35–37 °C. Strain 2.1T showed catalase and cytochrome c oxidase activity. Its polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, aminophospholipid and phospholipid. The only respiratory quinone was menaquinone 7, and the major cellular fatty acids were anteiso-C15 : 0, anteiso-C17 : 0, iso-C15 : 0, iso-C17 : 0 and palmitic acid (C16 : 0), which is consistent with other members of the genus Paenibacillus. The G+C content of the genomic DNA of strain 2.1T was 53.3 mol%. Phylogenetic analyses based on the 16S rRNA gene sequence similarity showed that strain 2.1T was closely related to Paenibacillus dendritiformis LMG 21716T (99.7 % similarity) and Paenibacillus thiaminolyticus DSM 7262T (98.8 %). The whole-genome average nucleotide identity between strain 2.1T and the type strains of P. dendritiformis and P. thiaminolyticus was 92 and 91 %, respectively, and thus lower than the 95 % threshold value for delineation of genomic prokaryotic species. Based on the results of phylogenetic, genomic, phenotypic and chemotaxonomic analyses we propose the name Paenibacillus melissococcoides sp. nov. for this novel Paenibacillus species. The type strain is 2.1T (=CCOS 2000T=DSM 113619T=LMG 32539T)

Dinitrogen fixation and dissolved organic nitrogen fueled primary production and particulate export during the VAHINE mesocosm experiment (New Caledonia lagoon)

International audienceIn the oligotrophic ocean characterized by nitrate (NO − 3) depletion in surface waters, dinitrogen (N 2) fixation and dissolved organic nitrogen (DON) can represent significant nitrogen (N) sources for the ecosystem. In this study, we deployed large in situ mesocosms in New Caledonia in order to investigate (1) the contribution of N 2 fixation and DON use to primary production (PP) and particle export and (2) the fate of the freshly produced particulate organic N (PON), i.e., whether it is preferentially accumulated and recycled in the water column or exported out of the system. The mesocosms were fertilized with phosphate (PO 3− 4) in order to prevent phosphorus (P) limitation and promote N 2 fixation. The diazotrophic community was dominated by diatom–diazotroph associations (DDAs) during the first part of the experiment for 10 days (P1) followed by the unicel-lular N 2-fixing cyanobacteria UCYN-C for the last 9 days (P2) of the experiment. N 2 fixation rates averaged 9.8 ± 4.0 and 27.7 ± 8.6 nmol L −1 d −1 during P1 and P2, respectively. NO − 3 concentrations ( 0.05) during P1 (9.0 ± 3.3 %) and P2 (12.6 ± 6.1 %). However, the e ratio that quantifies the efficiency of a system to export particulate organic carbon (POC export) compared to PP (e ratio = POC export / PP) was significantly higher (p 0.05) from the total amount of PON exported (0.10 ± 0.04 µmol L −1), suggesting a rapid and probably direct export of the recently fixed N 2 by the DDAs. During P2, both PON concentrations and PON export increased in the mesocosms by a factor 1.5–2. Unlike in P1, this PON production was not totally explained by the new N provided by N 2 fixation. The use of DON, whose concentrations decreased significantly (p < 0.05) from 5.3 ± 0.5 µmol L −1 to 4.4 ± 0.5 µmol L −1 , appeared to be the missing N source. The DON consumption (∼ 0.9 µmol L −1) during P2 is higher Published by Copernicus Publications on behalf of the European Geosciences Union. 4100 H. Berthelot et al.: Dinitrogen fixation and dissolved organic nitrogen fueled primary production than the total amount of new N brought by N 2 fixation (∼ 0.25 µmol L −1) during the same period. These results suggest that while DDAs mainly rely on N 2 fixation for their N requirements, both N 2 fixation and DON can be significant N sources for primary production and particulate export following UCYN-C blooms in the New Caledonia lagoon and by extension in the N-limited oceans where similar events are likely to occur

First occurrence of the Ichnogenus Selenichnites from the Middle Jurassic Strata of the Skoura Syncline (Middle Atlas, Morocco); Palaeoecological and palaeoenvironmental context

© 2015 Académie des sciences. Mesozoic strata of North Africa yield the first occurrence of the ichnogenus Selenichnites. The trace fossils occur on the top surface of a sandy carbonate deposit in the axis of a Middle Atlas syncline (Skoura Syncline, NE Morocco). The ichnofossil-bearing horizon belongs to the Late Bajocian-Early Bathonian Ich Timellaline/Bou Akrabene Formation. The trace fossils are crescent-shaped and the best preserved exhibits a posterior central axial impression (possible telson tail impression). They are interpreted as feeding burrows (fodinichnia) or hiding depressions of Xiphosurids or Limulids (horseshoe crabs) on a sandy carbonate substrate beneath a veneer of muddy deposits. The sedimentological character suggests a relatively protected shallow water subtidal palaeoenvironment preceding the Bathonian regression of the Atlas domain. This discovery provides the first evidence of xiphosurans or xiphosuran-like organisms inhabiting the southern shores of the Tethys in the Middle Jurassic

First occurrence of the Ichnogenus Selenichnites from the Middle Jurassic Strata of the Skoura Syncline (Middle Atlas, Morocco); Palaeoecological and palaeoenvironmental context

© 2015 Académie des sciences.Mesozoic strata of North Africa yield the first occurrence of the ichnogenus Selenichnites. The trace fossils occur on the top surface of a sandy carbonate deposit in the axis of a Middle Atlas syncline (Skoura Syncline, NE Morocco). The ichnofossil-bearing horizon belongs to the Late Bajocian-Early Bathonian Ich Timellaline/Bou Akrabene Formation. The trace fossils are crescent-shaped and the best preserved exhibits a posterior central axial impression (possible telson tail impression). They are interpreted as feeding burrows (fodinichnia) or hiding depressions of Xiphosurids or Limulids (horseshoe crabs) on a sandy carbonate substrate beneath a veneer of muddy deposits. The sedimentological character suggests a relatively protected shallow water subtidal palaeoenvironment preceding the Bathonian regression of the Atlas domain. This discovery provides the first evidence of xiphosurans or xiphosuran-like organisms inhabiting the southern shores of the Tethys in the Middle Jurassic

Comparative Genomics and Description of Putative Virulence Factors of Melissococcus plutonius, the Causative Agent of European Foulbrood Disease in Honey Bees.

In Europe, approximately 84% of cultivated crop species depend on insect pollinators, mainly bees. Apis mellifera (the Western honey bee) is the most important commercial pollinator worldwide. The Gram-positive bacterium Melissococcus plutonius is the causative agent of European foulbrood (EFB), a global honey bee brood disease. In order to detect putative virulence factors, we sequenced and analyzed the genomes of 14 M. plutonius strains, including two reference isolates. The isolates do not show a high diversity in genome size or number of predicted protein-encoding genes, ranging from 2.021 to 2.101 Mbp and 1589 to 1686, respectively. Comparative genomics detected genes that might play a role in EFB pathogenesis and ultimately in the death of the honey bee larvae. These include bacteriocins, bacteria cell surface- and host cell adhesion-associated proteins, an enterococcal polysaccharide antigen, an epsilon toxin, proteolytic enzymes, and capsule-associated proteins. In vivo expression of three putative virulence factors (endo-alpha-N-acetylgalactosaminidase, enhancin and epsilon toxin) was verified using naturally infected larvae. With our strain collection, we show for the first time that genomic differences exist between non-virulent and virulent typical strains, as well as a highly virulent atypical strain, that may contribute to the virulence of M. plutonius. Finally, we also detected a high number of conserved pseudogenes (75 to 156) per genome, which indicates genomic reduction during evolutionary host adaptation

Ultraviolet refractometry using field-based light scattering spectroscopy

Accurate refractive index measurement in the deep ultraviolet (UV) range is important for the separate quantification of biomolecules such as proteins and DNA in biology. This task is demanding and has not been fully exploited so far. Here we report a new method of measuring refractive index using field-based light scattering spectroscopy, which is applicable to any wavelength range and suitable for both solutions and homogenous objects with well-defined shape such as microspheres. The angular scattering distribution of single microspheres immersed in homogeneous media is measured over the wavelength range 260 to 315 nm using quantitative phase microscopy. By least square fitting the observed scattering distribution with Mie scattering theory, the refractive index of either the sphere or the immersion medium can be determined provided that one is known a priori. Using this method, we have measured the refractive index dispersion of SiO2 spheres and bovine serum albumin (BSA) solutions in the deep UV region. Specific refractive index increments of BSA are also extracted. Typical accuracy of the present refractive index technique is ≤0.003. The precision of refractive index measurements is ≤0.002 and that of specific refractive index increment determination is ≤0.01 mL/g.Hamamatsu CorporationNational Science Foundation (DBI-0754339)National Center for Research Resources of the National Institutes of Health (P41-RR02594-18

Processing–structure–property relations of chemically bonded phosphate ceramic composites

ABSTRACT: Mechanical properties and microstructures of a chemically bonded phosphate ceramic (CBPC) and its composite with 1⋅0 wt% graphite nanoplatelets (GNPs) reinforcement have been investigated. Microstructure was identified by using optical and scanning electron microscopes, X-ray tomography, and X-ray diffraction. In addition, weight loss of the resin at room temperature was studied. The microstructure characterization shows that CBPC is itself a composite with several crystalline (wollastonite and brushite) and amorphous phases. SEM and micro tomography show a homogeneous distribution of crystalline phases. Bending and compression strength of the CBPC was improved by reducing bubbles via preparation in vacuum