Raman microspectroscopy as an identification tool within the phylogenetically homogeneous 'Bacillus subtilis' group

Vibrational methods have multiple advantages compared to more classic, chemotaxonomic and even molecular microbial tools for the identification of bacteria. Nevertheless, their definite breakthrough in diagnostic microbiology laboratories is determined by their identification potential. This paper reports on the profound evaluation of Raman spectroscopy to identify closely related species by means of 68 Bacillus strains that are assigned or closely related to the phylogenetically homogeneous ‘Bacillus subtilis’-group (sensu stricto). These strains were chosen to represent biological variation within the selected species and to create a realistic view on the possibilities of this technique

The evaluation resulted in 49/54 correct identifications at the species level for intern and 15/19 for extern testing. The correct identification of strains, which were not represented in the training set, supports the potential as an identification tool within the ‘B. subtilis group’. Considering the vague borderline between the species studied, Raman spectroscopy can be regarded here as a promising application for identifications at the species level.     

Stimulated Raman microscopy (CARS): From principles to applications

A new technique in microscopy is now available which permits to image specific molecular bonds of chemical species present in cells and tissues. The so called Coherent Anti-Stokes Raman Scattering (CARS) approach aims at maximizing the light matter interaction between two laser pulses and an intrinsic molecular vibrational level. This is possible through a non linear process which gives rise to a coherent radiation that is greatly enhanced when the frequency difference between the two laser pulses equals the Raman frequency of the aimed molecular bond. Similar to confocal microscopy, the technique permits to build an image of a molecular density within the sample but doesn't require any labelling or staining since the contrast uses the intrinsic vibrational levels present in the sample. Images of lipids in membranes and tissues have been reported together with their spectral analysis. In the case of very congested media, it is also possible to use a non invasive labelling such as deuterium which shifts the molecular vibration of the C-H bond down to the C-D bond range which falls in a silent region of the cell and tissue vibrational spectra. Such an approach has been used to study lipid phase in artificial membranes. Although the technique is still under development, CARS has now reach a maturity which will permit to bring the technology at a commercial stage in the near future. The last remaining bottleneck is the laser system which needs to be simplified but solutions are now under evaluation. When combined with others more conventional techniques, CARS should give its full potential in imaging unstained samples and like two photons techniques has the potential of performing deep tissues imaging.     

Effects of noise on inner ear

The effects of noise on health depend both on individual factors and characteristics of sound exposure. In case of acoustic trauma, reversible or irreversible lesions of inner ear components are possible. Most often there is immediately an acute tinnitus and hearing loss. Audiometric tests demonstrate hearing loss on the high frequency, generally focused on 4 kHz. Immediate treatment is recommended even there is no currently indicator of the ability to restore hearing. New perspectives on treatment are directed to local treatment and/or using new procedure as antioxidative treatment. Occupational and leisure are the two conditions in which chronic exposure to noise is found. Detection and prevention of noise-induced hearing loss is easier in case of industrial workers than in case of noise exposition for musicians and other sounds and stage technicians or concert managers, and of course non-professional with exposure to amplified music.     

Monitoring Bacterial Community of Human Gut Microbiota Reveals an Increase in Lactobacillus in Obese Patients and Methanogens in Anorexic Patients

Background

Studies of the bacterial communities of the gut microbiota have revealed a shift in the ratio of Firmicutes and Bacteroidetes in obese patients. Determining the variations of microbial communities in feces may be beneficial for the identification of specific profiles in patients with abnormal weights. The roles of the archaeon Methanobrevibacter smithii and Lactobacillus species have not been described in these studies.

Methods and Findings

We developed an efficient and robust real-time PCR tool that includes a plasmid-based internal control and allows for quantification of the bacterial divisions Bacteroidetes, Firmicutes, and Lactobacillus as well as the methanogen M. smithii. We applied this technique to the feces of 20 obese subjects, 9 patients with anorexia nervosa, and 20 normal-weight healthy controls. Our results confirmed a reduction in the Bacteroidetes community in obese patients (p<0.01). We found a significantly higher Lactobacillus species concentration in obese patients than in lean controls (p = 0.0197) or anorexic patients (p = 0.0332). The M. smithii concentration was much higher in anorexic patients than in the lean population (p = 0.0171).

Conclusions

Lactobacillus species are widely used as growth promoters in the farm industry and are now linked to obesity in humans. The study of the bacterial flora in anorexic patients revealed an increase in M. smithii. This increase might represent an adaptive use of nutrients in this population.     

Specific Expression of BMP2/4 Ortholog in Biomineralizing Tissues of Corals and Action on Mouse BMP Receptor

Bone morphogenetic proteins (BMPs) are members of the transforming growth factor β superfamily, and have been identified by their ability to induce bone formation in vertebrates. The biomineral-forming process, called biomineralization, is a widespread process, present in all kingdoms of living organisms and among which stony corals are one of the major groups of calcifying animals. Here, we report the presence of a BMP2/4 ortholog in eight species of adult corals. The synthesis of such a protein by the calcifying epithelium of corals suggests that coral BMP2/4 plays a role in skeletogenesis, making BMP the first common protein involved in biomineralization among Eumetazoans. In addition we show that recombinant coral BMP2/4 is able to inhibit human BMP2-induced osteoblastic differentiation in mesenchymal C2C12 cells. We suggest that this inhibition results from a competition between coral BMP2/4 and human BMP2, indicating conservation of binding affinity of BMP and its receptor during evolution from corals to vertebrates. Further studies are needed to understand interactions between coral BMP2/4 and its receptors, and, thus, the action of BMP2/4 in adult corals. Nucleotide sequence of the coral BMP2/4 genes cloned in this study is available in the GenBank under the accession number EU785981 (Stylophora pistillata) and EU785982 (Acropora sp.).     

Metagenomic approach studying the taxonomic and functional diversity of the bacterial community in a mesotrophic lake (Lac du Bourget – France)

The main goals of this work were to identify the metabolic pathways of the bacterial community in a lacustrine ecosystem and to establish links between taxonomic composition and the relative abundances of these metabolic pathways. For this purpose, we analysed a 16S rRNA gene library obtained by gene amplification together with a sequence library of both insert ends on c . 7700 fosmids. Whatever the library used, Actinobacteria was the most abundant bacterial group, followed by Proteobacteria and Bacteroidetes . Specific aquatic clades such as acI and acIV ( Actinobacteria ) or LD12 and GOBB-C201 ( Alphaproteobacteria ) were found in both libraries. From comparative analysis of metagenomic libraries, the metagenome of this lake was characterized by overrepresentation of genes involved in the degradation of xenobiotics mainly associated with Alphaproteobacteria . Actinobacteria were mainly related to metabolic pathways involved in nucleotide metabolism, cofactors, vitamins, energy, replication and repair. Betaproteobacteria appeared to be characterized by the presence of numerous genes implicated in environmental information processing (membrane transport and signal transduction) whereas glycan and carbohydrate metabolism pathways were overrepresented in Bacteroidetes . These results prompted us to propose hypotheses on the ecological role of these bacterial classes in lacustrine ecosystems.     

Consequence of omitting or adding a meal in man on body composition, food intake, and metabolism

Objective: To investigate in man the consequence on body composition and related biological and metabolic parameters of omitting or adding a meal. Research Methods and Procedures: Twenty‐four young normal‐weight male subjects were recruited, 12 usual four‐meal and 12 usual three‐meal eaters, differing only in the consumption of an afternoon meal. They omitted or added a fourth meal during a 28‐day habituation period and were asked to report their intake on three 3‐day occasions. Before and after this habituation period, subjects participated in a session with a time‐blinded procedure, and blood was collected continuously from lunch to the spontaneously requested dinner. Body composition, respiratory quotient, and biochemical parameters were measured in the late evening preceding each session. Results: Omitting a meal was followed by increases in fat mass (360 ± 115 grams, p < 0.05), late evening leptin concentration (20.7 ± 11.0%, p < 0.05), and respiratory quotient (3.7 ± 1.4%, p < 0.05). Increase in the percentage of dietary fat during the habituation period (+4.1 ± 2.0%, p < 0.05) was correlated with fat mass (r = 0.66, p < 0.05). Adding a meal had no effect, but, in both groups, the change in energy content at this fourth eating occasion was correlated with the change in adiposity. Discussion: Our results suggest that adiposity may increase when young lean male subjects switch from a four‐ to a three‐meal pattern by removing their usual afternoon meal. This effect could be partly mediated by a change in the macronutrient composition of the diet.