The Arthrobacter arilaitensis Re117 Genome Sequence Reveals Its Genetic Adaptation to the Surface of Cheese

Arthrobacter arilaitensis is one of the major bacterial species found at the surface of cheeses, especially in smear-ripened cheeses, where it contributes to the typical colour, flavour and texture properties of the final product. The A. arilaitensis Re117 genome is composed of a 3,859,257 bp chromosome and two plasmids of 50,407 and 8,528 bp. The chromosome shares large regions of synteny with the chromosomes of three environmental Arthrobacter strains for which genome sequences are available: A. aurescens TC1, A. chlorophenolicus A6 and Arthrobacter sp. FB24. In contrast however, 4.92% of the A. arilaitensis chromosome is composed of ISs elements, a portion that is at least 15 fold higher than for the other Arthrobacter strains. Comparative genomic analyses reveal an extensive loss of genes associated with catabolic activities, presumably as a result of adaptation to the properties of the cheese surface habitat. Like the environmental Arthrobacter strains, A. arilaitensis Re117 is well-equipped with enzymes required for the catabolism of major carbon substrates present at cheese surfaces such as fatty acids, amino acids and lactic acid. However, A. arilaitensis has several specificities which seem to be linked to its adaptation to its particular niche. These include the ability to catabolize D-galactonate, a high number of glycine betaine and related osmolyte transporters, two siderophore biosynthesis gene clusters and a high number of Fe3+/siderophore transport systems. In model cheese experiments, addition of small amounts of iron strongly stimulated the growth of A. arilaitensis, indicating that cheese is a highly iron-restricted medium. We suggest that there is a strong selective pressure at the surface of cheese for strains with efficient iron acquisition and salt-tolerance systems together with abilities to catabolize substrates such as lactic acid, lipids and amino acids

Microphysical and thermodynamic phase analyses of Arctic low-level clouds measured above the sea ice and the open ocean in spring and summer

Airborne in situ cloud measurements were carried out over the northern Fram Strait between Greenland and Svalbard in spring 2019 and summer 2020. In total, 811 min of low-level cloud observations were performed during 20 research flights above the sea ice and the open Arctic ocean with the Polar 5 research aircraft of the Alfred Wegener Institute. Here, we combine the comprehensive in situ cloud data to investigate the distributions of particle number concentration N, effective diameter Deff, and cloud water content CWC (liquid and ice) of Arctic clouds below 500 m altitude, measured at latitudes between 76 and 83◦ N. We developed a method to quantitatively derive the occurrence probability of their thermodynamic phase from the combination of microphysical cloud probe and Polar Nephelometer data. Finally, we assess changes in cloud microphysics and cloud phase related to ambient meteorological conditions in spring and summer and address effects of the sea ice and open-ocean surface conditions. We find median N from 0.2 to 51.7 cm−3 and about 2 orders of magnitude higher N for mainly liquid clouds in summer compared to ice and mixed-phase clouds measured in spring. A southerly flow from the sea ice in cold air outbreaks dominates cloud formation processes at temperatures mostly below −10 ◦C in spring, while northerly warm air intrusions favor the formation of liquid clouds at warmer temperatures in summer. Our results show slightly higher N in clouds over the sea ice compared to the open ocean, indicating enhanced cloud formation processes over the sea ice. The median CWC is higher in summer (0.16 gm−3 ) than in spring (0.06 gm−3 ), as this is dominated by the available atmospheric water content and the temperatures at cloud formation level. We find large differences in the particle sizes in spring and summer and an impact of the surface conditions, which modifies the heat and moisture fluxes in the boundary layer. By combining microphysical cloud data with thermodynamic phase information from the Polar Nephelometer, we find mixed-phase clouds to be the dominant thermodynamic cloud phase in spring, with a frequency of occurrence of 61 % over the sea ice and 66 % over the ocean. Pure ice clouds exist almost exclusively over the open ocean in spring, and in summer the cloud particles are most likely in the liquid water state

MOSAiC-ACA and AFLUX - Arctic airborne campaigns characterizing the exit area of MOSAiC

Two airborne field campaigns focusing on observations of Arctic mixed-phase clouds and boundary layer processes and their role with respect to Arctic amplification have been carried out in spring 2019 and late summer 2020 over the Fram Strait northwest of Svalbard. The latter campaign was closely connected to the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. Comprehensive data sets of the cloudy Arctic atmosphere have been collected by operating remote sensing instruments, insitu probes, instruments for the measurement of turbulent fluxes of energy and momentum, and dropsondes on board the AWI research aircraft Polar 5. In total, 24 flights with 111 flight hours have been performed over open ocean, the marginal sea ice zone, and sea ice. The data sets follow documented methods and quality assurance and are suited for studies on Arctic mixed-phase clouds and their transformation processes, for studies with a focus on Arctic boundary layer processes, and for satellite validation application

Caractérisation et modélisation de couches minces de 3C-SiC pour applications aux microsystèmes en environnements sévères.

Effectué dans le cadre du développement des microtechnologies pour l\u27environnement sévère, ce travail s\u27articule autour de deux axes principaux. Dans une première partie, une étude détaillée des caractéristiques physique de couches de 3C-SiC épitaxiées sur substrat silicium, est menée. Les résultats issus de cette étude portent notamment sur la maîtrises de l\u27état de contrainte résiduelle présente dans les couches de 3C-SiC élaborées en fonction des conditions d\u27épitaxie, afin d\u27approcher une contrainte quasi nulle. De plus, la faisabilité de membranes carrées auto-suspendues de 3C-SiC de 3 à 8 micromètres de côté est démontré. L\u27étude sous charge de telles structures, nous a permis d\u27extraire le module d\u27Young des différentes couches. Et d\u27avoir accès aux contraintes résiduelles présentes dans les membranes de 3C-SiC. Elle nous a également permis de mieux cerner les origines de la disparité des états de contrainte dans les couches de SiC sur pleine plaque de silicium. Dans une seconde partie, nous avons développé deux modèles de structures par éléments finis à l\u27aide du logiciel Ansys 5.4, comportant un film mince de SiC. L\u27un modélise les contraintes thermoélastiques présentes dans les couches de SiC sur pleine plaque de silicium. En comparant ce modèle simple à des résultats expérimentaux, il est possible de valider le choix des paramètres physiques issus de la littérature, utilisés pour la FEM. L\u27autre modèle FEM développé, est celui d\u27une membrane carrée auto-suspendue de 3C-SiC qui, comparé aux mesures sous charges effectuées sur structures réelles, donne des résultats très probants lorsque les contraintes résiduelles des couches sont purement thermoélastiques (à 5% près)

French Airborne Measurement Platform (PMA) cloud particle size distribution and volumic cloud particle diffusion properties dataset near Svalbard for AFLUX measurement campaign with POLAR 5 in 2019

This data set is composed of in-situ measurement of arctic cloud microphysical properties (particle size distribution and volumic cloud particle diffusion properties) observed during the AFLUX-AC3 campaign, which occurred between 19 March and 11 April 2019. These measurements were made using the 2D stereoscopic (2D-S, SPEC Inc.) and Polar Nephelometer (Gayet et al., 1997) probes from the airborne measurement platform of the Laboratoire de Météorologie Physique (CNRS/UCA, Aubière, France). There is one file per flight. All files are in NetCDF format, with a complete description of the parameters inside. A detailed list of the parameters present in the data set is added in a separate document

French Airborne Measurement Platform (PMA) cloud particle size distribution and volumic cloud particle diffusion properties dataset near Svalbard for MOSAIC-ACA measurement campaign in 2020

This data set is composed of in-situ measurement of arctic cloud microphysical properties (particle size distribution and volumic cloud particle diffusion properties) observed during the MOSAIC-ACA campaign, which occurred between August 30th and September 13th 2020. These measurements were made using the 2D stereoscopic (2D-S, SPEC Inc.) and Polar Nephelometer (Gayet et al., 1997) probes from the airborne measurement platform of the Laboratoire de Météorologie Physique (CNRS/UCA, Aubière, France). There is one file per flight. All files are in NetCDF format, with a complete description of the parameters inside. A detailed list of the parameters present in the data set is added in a separate document

CDP, CIP and PIP In-situ arctic cloud microphysical properties observed during ACLOUD-AC3 campaign in June 2017

This data set is composed of in-situ measurement of arctic cloud microphysical properties observed during the ACLOUD-AC3 campaign which occurred during June 2017. These measurements were made using the CDP, CIP and PIP probes from the airborne measurement platform of the Laboratoire de Météorologie Physique (CNRS/UCA, Aubière, France). There is one file per flight. All files are in NetCDF format with a complete description of the parameters inside. A detailed description of the data processing will be done in an upcoming data paper

Characterization of Arctic mixed phase clouds at regional and small scales

International audiencePrevious observations suggest that Mixed Phase Clouds (MPC) occur frequently in the Arctic and often persist for many days due to a combination of local processes (microphysical and radiative for instance) and larger scale meteorological conditions. These low-level liquid containing clouds exert a large influence on the surface radiative fluxes and feedbacks on Arctic climate. However, understanding the spatial phase distribution within MPC remains a challenge.In this study, the MPC macrophysical and microphysical properties are investigated at a regional scale using CloudSat and CALIPSO observations (2007-2010) and at smaller scale with airborne in situ measurements performed in the Svalbard region.Results show that MPCs have a mean frequency of occurrence ranging from 30% (end of winter) to 55% (in autumn) in the Arctic. In the Svalbard region, the frequencies of occurrence are significantly higher with values ranging from 45% to 60%. MPCs are especially located at low altitudes, below 3000m, where their occurrence reaches 90%, particularly in winter, spring and autumn. Moreover, results highlight that MPCs are statistically more frequent over open sea than sea ice or land. These observations also allow us to assess how already performed small scale airborne measurements are representative of the variety of clouds encountered in the Arctic. In situ measurements (44 vertical profiles obtained during ASTAR, POLARCAT, SORPIC) are statistically analyzed to derive representative profiles of MPC microphysical and optical properties (optical depth, liquid/water fraction, ice crystals habit). These analyses should contribute to a better understanding of processes occurring in arctic MPC

Arctic mixed phase clouds properties based on airborne in situ and remote sensing measurements

Clouds radiation feedback processes in Polar Regions have been identified as key uncertainties in the prediction of global climate in GCMs. To better understand clouds-radiation interactions in these regions, knowledge of arctic clouds properties has to be improved. In particular, mixed phased clouds, which frequently occur in Arctic, present a large variety of physical characteristics and involve very complex microphysical and dynamical processes between liquid and ice phases, currently not yet well understood, and poorly documented. In order to improve the knowledge of arctic clouds properties, the Laboratoire de Météorologie Physique (LaMP) is involved from several years in several airborne measurement campaigns dedicated to the study of arctic clouds (ASTAR 2004, ASTAR 2007, POLARCAT 2008, SORPIC 2010), providing optical and microphysical in situ measurements from a unique combination of airborne probes (CPI, Polar néphélomètre, PMS FFS-100, 2D-S, Nevzorov...). Furthermore, the airborne radar/lidar system RALI from LATMOS will provide in addition active remote sensing measurements. This study will present a statistical analysis of arctic mixed phase clouds optical and microphysical properties based on these in situ measurements, representing more than 40 flights. The first main objective of this study is to investigate the ice particles and clouds droplets growth processes into the clouds, and their interaction with radiation. The second main objective is to provide accurate profiles of relevant clouds parameters to contribute to the improvement of clouds representation in global and mesoscale models and to improve airborne and spatial remote sensing retrievals algorithms (CALIPSO, CloudSat, EarthCare...). These relevant parameters are for example the thermodynamic phase, geometrical characteristics (height, thickness), and optical and microphysical properties (asymmetry parameters, optical depth, liquid/water fraction, ice crystals morphology, size and concentration, IWC...)

Expression Analysis in Grapevine by In Situ Hybridization and Immunohistochemistry

International audienc