Aix-Marseille University

About: Aix-Marseille University is a education organization based out in Marseille, France. It is known for research contribution in the topics: Population & Galaxy. The organization has 24326 authors who have published 54240 publications receiving 1455416 citations. The organization is also known as: University Aix-Marseille & université d'Aix-Marseille.

Filming Biomolecular Processes by High-Speed Atomic Force Microscopy

Abstract: In the history of science and technology, researchers have always undertaken endeavors to enhance the degree of “directness of measurement”. With “directness of measurement”, we conceptualize that the essence of the object under investigation, the structure, dynamics, and function of biological samples in the scope of this Review, is entirely and straightforwardly assessed by the measurement, bypassing hypotheses and intricate data analysis. When the degree of measurement directness is low, conclusions derived from the gleaned data often differ depending on the formulation of hypotheses, analysis models, and the data interpretation. That is why conceptual consensus about a specific issue of the studied object is rarely reached based on indirect data. This is often the case for studies of structure–function relationship of proteins. Previously, scientists had to understand distinct qualities of proteins by measuring a sample containing a huge number of molecules. The results are ensemble-averaged quantities (often at equilibrium) that provide only limited information on the proteins of study. Proteins are dynamic in nature and work at the single-molecule level. Protein molecules fluctuate, undergo structural changes, bind to and dissociate from interaction partners, and traverse a range of energy and chemical states during molecular action. Most, if not all, of these dynamics and their statistical distributions are convoluted and hidden in ensemble averaging measurements. To overcome the limitations of ensemble measurements, single-molecule biophysics was developed more than two decades ago, with the use of fluorescence microscopy,1,2 optical spectroscopy,3,4 and optical and magnetic tweezers,5,6 whose performances were further improved by the advancements of improved optical microscopes, lasers, electronics, computers, and high-sensitivity video cameras and sensors. Using these techniques, our understanding of the functional mechanism of proteins has made significant steps forward. Moreover, super-resolution optical microscopy techniques bypassing the diffraction limit for fluorophore localization have recently been added to fluorescence microscopy.7−9 However, the degree of directness of measurement is still limited, because the protein molecules themselves are invisible in these single-molecule measurements. Protein structure is typically studied by X-ray crystallography, electron microscopy (EM), and nuclear magnetic resonance (NMR) spectroscopy. To date, these techniques have revealed detailed three-dimensional structures of over 94 000 proteins (Protein Data Bank (PDB), http://www.rcsb.org/pdb/home/home.do), with a growth rate of about 8000 novel structures per year (2010–2013). Yet, these techniques make use of ensemble averaging, and, more seriously, the obtained structures are merely limited to static snapshots of fixed conformations. Thus, the simultaneous and direct observation of structure, dynamics, and function of single protein molecules has long been infeasible, and hence the materialization of a technique allowing such an observation has long been awaited in biological sciences. An ideal microscopy technique that allows simultaneous observation of structure, dynamics, and function of single protein molecules has to meet all of the following conditions (see Table 1): (i) in-liquid specimen imaging, (ii) high spatial resolution, (iii) high temporal resolution, (iv) low invasiveness to the specimen, and (v) direct imaging of the specimen without the use of markers (in other words, resolving the structure of the specimen itself). Although efforts have been made to develop environmental electron microscopy techniques capable of observing unstained biological specimens in solutions,10 the strong electron dose that is required to achieve high contrast and spatial resolution instantaneously denatures the sample. Achieving the above-described goals by EM is a highly difficult, if not impossible, task. Conventional atomic force microscopy11 (AFM) meets most of the above-mentioned conditions, except for the third condition, that is, high temporal resolution, and the fourth condition, that is, low invasiveness, is only moderately satisfied. Table 1 Feasibility Comparison of Three Types of Microscopy

The VIMOS-VLT deep survey - Evolution of the galaxy luminosity function up to z = 2 in first epoch data

Abstract: We investigate the evolution of the galaxy luminosity function from the VIMOS-VLT Deep Survey (VVDS) from the present to z=2 in five (U, B, V, R and I) rest-frame band-passes. We use the first epoch VVDS deep sample of 11,034 spectra selected at 17.5 <= I_{AB} <= 24.0, on which we apply the Algorithm for Luminosity Function (ALF), described in this paper. We observe a substantial evolution with redshift of the global luminosity functions in all bands. From z=0.05 to z=2, we measure a brightening of the characteristic magnitude M* included in the magnitude range 1.8-2.5, 1.7-2.4, 1.2-1.9, 1.1-1.8 and 1.0-1.6 in the U, B, V, R and I rest-frame bands, respectively. We confirm this differential evolution of the luminosity function with rest-frame wavelength, from the measurement of the comoving density of bright galaxies (M < M*(z=0.1)). This density increases by a factor of around 2.6, 2.2, 1.8, 1.5, 1.5 between z=0.05 and z=1 in the U, B, V, R, I bands, respectively. We also measure a possible steepening of the faint-end slope of the luminosity functions, with \\Delta\\alpha ~ -0.3 between z=0.05 and z=1, similar in all bands.

Epidemiology and morbidity of regional anesthesia in children : a follow-up one-year prospective survey of the French-Language Society of Paediatric Anaesthesiologists (ADARPEF)

Abstract: BACKGROUND: The French-Language Society of Paediatric Anaesthesiologists (ADARPEF) designed a 1-year prospective, multicenter and anonymous study to update both epidemiology and morbidity of regional anesthesia in children. METHODS: From November 2005 to October 2006, data from participating hospitals were recorded using an identification form, a data recording form, and a complication form. Information collected included the characteristics of the hospitals, the number and type of regional anesthetics (RA), the age of the involved children as well as the incidence, and type of complications. RESULTS: Data collected in 47 institutions included 104,612 pure general anesthesias (GAs), 29,870 GAs associated with regional blocks, and 1262 pure regional blocks. Central blocks accounted for 34% of all RA. Peripheral blocks (66%) were upper or lower limb blocks (29% of peripheral blocks), trunk blocks, and face blocks (71%). In children aged ≤3 years, the percentage of central blocks was similar to the peripheral ones (45% vs 55), while in older children, peripheral blocks were more than four times used than central ones. Complications (41 involving 40 patients) were rare and usually minor. They did not result in any sequelae. The study revealed an overall rate of complication of 0.12%; CI 95% [0.09-0.17], significantly six times higher for central than for peripheral blocks. CONCLUSIONS: As a result of the low rate of complications, RA techniques have a good safety profile and can be used to provide postoperative analgesia. In addition, the results should encourage anesthesiologists to continue to use peripheral instead of central (including caudal) blocks as often as possible when appropriate.

The Rosa genome provides new insights into the domestication of modern roses.

Abstract: Roses have high cultural and economic importance as ornamental plants and in the perfume industry. We report the rose whole-genome sequencing and assembly and resequencing of major genotypes that contributed to rose domestication. We generated a homozygous genotype from a heterozygous diploid modern rose progenitor, Rosa chinensis ‘Old Blush’. Using single-molecule real-time sequencing and a meta-assembly approach, we obtained one of the most comprehensive plant genomes to date. Diversity analyses highlighted the mosaic origin of ‘La France’, one of the first hybrids combining the growth vigor of European species and the recurrent blooming of Chinese species. Genomic segments of Chinese ancestry identified new candidate genes for recurrent blooming. Reconstructing regulatory and secondary metabolism pathways allowed us to propose a model of interconnected regulation of scent and flower color. This genome provides a foundation for understanding the mechanisms governing rose traits and should accelerate improvement in roses, Rosaceae and ornamentals.