Editorial: biodegradable materials

This Special Issue “Biodegradable Materials” features research and review papers concerning recent advances on the development, synthesis, testing and characterisation of biomaterials. These biomaterials, derived from natural and renewable sources, offer a potential alternative to existing non-biodegradable materials with application to the food and biomedical industries amongst many others. In this Special Issue, the work is expanded to include the combined use of fillers that can enhance the properties of biomaterials prepared as films. The future application of these biomaterials could have an impact not only at the economic level, but also for the improvement of the environment

Estimation in situ de la respiration des boues activées par application d'un bilan sur l'oxygène

Dans les stations d'épuration à boues activées il est essentiel de maintenir une biomasse de bonne qualité ceci afin que l'eau soit traitée correctement. Un des paramètres caractéristiques de l'activité de la biomasse est la respiration spécifique (c'est à dire la quantité d'oxygène consommé par unité de masse de biomasse et par unité de temps). Cette respiration peut être mesurée à l'aide d'appareils spécifiques (respiromètres) ou déduite à partir de mesures réalisées en ligne. Une méthode d'analyse de données destinée à déduire la respiration spécifique à partir de mesures simples (débits et concentration en oxygène dissous) a été mise au point et testée. Grâce au faible coût de mise en oeuvre de cette technique il devient raisonnable d'utiliser la respiration spécifique comme paramètre de conduite automatisée des stations d'épuration.In activated sludge wastewater treatment plants, the activity of the biomass is essential if effluent quality standards are to be met. One of the parameters that characterizes the activity of activated sludge is the specific oxygen uptake rate (the amount of oxygen consumed per unit mass of biomass and per unit time). This rate may be measured using specialised apparatus (respirometer) or deduced from on-line measurements. A technique to deduce the specific oxygen uptake rate from simple measurements (flow rate, dissolved oxygen concentrations) has been developed and tested. This technique involves low cost probes and therefore specific oxygen uptake rate estimations may be used for treatment plant automation

Etude de la nutrition des saumons et contribution à la création d'une filière de production de saumons Label Rouge

De nombreuses études ont mesuré l'efficacité de stratégies alimentaires sur la qualité de la chair de saumons atlantique. De plus, des questions de pérennité des ressources halieutiques et de l'utilisation de ressources végétales de substitution se posent désormais en production aquacole. Cette thèse dresse un bilan des principaux paramètres influençant la qualité des saumons Atlantique, puis pose les bases scientifiques au développement d'une filière dans une démarche de développement durable environnemental et sociétal. Deux cycles d'élevage ont permis de mettre en place un nouveau cahier des charges Label Rouge. Avec une vitesse de croissance lente, le facteur k a été faible et le profil en acides gras de la chair s'est rapproché de celui des saumons sauvages, avec un ratio oméga 3/6 supérieur à 3,3. Les tests statistiques ont montré la position intermédiaire du saumon Label Rouge entre le saumon standard et le saumon sauvage

Synthetic studies towards the total synthesis of hexacyclinic acid

In the first chapter of this thesis, published works found in the literature about hexacyclinic acid and FR182877 are reported and commented. A quick summary of the previous work done in the Prunet group is also described. In the second and third chapter, a more detailed account of the work undertaken during this PhD was given. Firstly, syntheses of two ABC tricycles incorporating tert-butyl and (trimethylsilyl)ethyl esters were undertaken. These syntheses include two key steps previously developed in the group, a diastereoselective Michael addition and a Snider cyclisation. Multiple conditions for the hydrolysis of the esters were attempted but none of them gave the desired product. The main part of this work is focused on the synthesis of a CDEF model and in particular about the development of the key step, the formation of a nine-membered ring. Several DEF fragments were synthesised in short synthetic sequences and as single isomers. Six different synthetic pathways were developed in total and a novel method, a Michael/elimination reaction, was found to be a very efficient way to close the desired medium-size ring. From the nine-membered ring, regioselective reduction and palladium catalysed allylic substitution led to the formation of the CDF tricycle. Final steps of the synthesis were fruitless and led only to decomposition. A synthesis of a chiral C-ring was also developed during this PhD. Finally, another project was undertaken, not related to hexacyclinic acid. Methodology developed in the group for the diastereoselective formation of trisubstituted alkenes employing a temporary silicon-tethered ring-closing metathesis was extended to homoallylic alcohols. The first steps of the method were similar to the previous methodology but the end-game had to be modified in favour of an oxidation/reduction sequence to successfully obtain the desired products with the correct geometry. In the fourth chapter, procedures and analytical data for the synthesised compounds previously described are reported

La langue bretonne à Arradon au XXe siècle

Le changement de langue, du breton au français, qui s’opère en Basse-Bretagne au XXe siècle est étudié à l’échelle d’une commune de la région vannetaise : Arradon. La démarche ethno-socio-linguistique met en relief les témoignages oraux de quelques personnes dont le breton est la langue maternelle. Des représentations théâtrales populaires, dérivées de vieux mystères en breton, sont évoquées dans cet article et témoignent d’une pratique culturelle du breton aux portes de Vannes vers 1930.Language change, from Breton to French, occuring in Western Brittany during XXth century, is studied on a village scale of the Vannes area: Arradon. Ethno-socio-linguistic approach enlighten oral accounts from a few native Breton speakers. Popular theater playing, from old breton ‘mystères’, is the topic of this paper, showing cultural practices in Breton nearby Vannes in around 1930

BLAST-EXPLORER helps you building datasets for phylogenetic analysis

<p>Abstract</p> <p>Background</p> <p>The right sampling of homologous sequences for phylogenetic or molecular evolution analyses is a crucial step, the quality of which can have a significant impact on the final interpretation of the study. There is no single way for constructing datasets suitable for phylogenetic analysis, because this task intimately depends on the scientific question we want to address, Moreover, database mining softwares such as BLAST which are routinely used for searching homologous sequences are not specifically optimized for this task.</p> <p>Results</p> <p>To fill this gap, we designed BLAST-Explorer, an original and friendly web-based application that combines a BLAST search with a suite of tools that allows interactive, phylogenetic-oriented exploration of the BLAST results and flexible selection of homologous sequences among the BLAST hits. Once the selection of the BLAST hits is done using BLAST-Explorer, the corresponding sequence can be imported locally for external analysis or passed to the phylogenetic tree reconstruction pipelines available on the Phylogeny.fr platform.</p> <p>Conclusions</p> <p>BLAST-Explorer provides a simple, intuitive and interactive graphical representation of the BLAST results and allows selection and retrieving of the BLAST hit sequences based a wide range of criterions. Although BLAST-Explorer primarily aims at helping the construction of sequence datasets for further phylogenetic study, it can also be used as a standard BLAST server with enriched output. BLAST-Explorer is available at <url>http://www.phylogeny.fr</url></p

Cinétiques de biodégradation par boues activées de la matière organique soluble d'un effluent synthétique

L'approche expérimentale choisie pour cette étude a eu pour objet de mesurer en conditions batch, les cinétiques d'élimination de la demande chimique en oxygène soluble d'un effluent synthétique mis en contact avec des boues activées d'origine différente. Les essais conduits en laboratoire ont été réalisés en faisant varier le rapport So/Xo (mg de DCO initiale par mg de matières volatiles initiales) telles que les concentrations en So et en Xo correspondent aux concentrations en DCO soluble (DCOs) et en matières volatiles (MV) rencontrées sur les stations d'épuration. Les essais ont été effectués sous aération continue à 20 °C en mettant en contact l'effluent synthétique et de la boue activée prélevée depuis 24 h et stockée à 4 °C dans l'attente de l'essai. De ce fait, la valeur de So mesurée au début de l'essai représente la concentration en DCO amenée par l'effluent synthétique (Seff) et celle amenée par l'inoculum de boue activée (Sb) représentant selon les essais de 5 à 70 % de la DCO de l'essai. Les profils de cinétique d'élimination de la DCO soluble obtenus pour différentes conditions d'essai s'ajustent, selon les valeurs de So/Xo (So/Xo variant de 0,15 à 2,17 ) à une fonction du premier ordre par rapport au substrat ou à une fonction sigmoïde. Le type de fonction cinétique d'élimination est également contrôlé par la proportion de la DCO amenée par l'inoculum.The conventional activated sludge process used for wastewater treatment removes from 80 to 95% of the total organic matter. However, a quantity of "not well identified" (particular, colloidal and soluble) organic matter is always present in the treated effluent. Reducing this residual (and improving the treatment efficiency) requires knowledge of the origin of that organic matter and especially to determine the fraction originating from the influent and the fraction generated by the biomass.This research has been conducted in batch conditions and studies the soluble COD (CODs) removal kinetics of a synthetic effluent (casein + starch + acetate + mineral salts), in contact with different activated sludge originating from six different wastewater treatment plants (loads varying from 0.06 to 1.14 kg BOD[inf]5/kg VSS. d).Experiments have been conducted with different So/Xo values (ratio between CODs initial concentration and VSS initial concentration) in order that these values correspond to the CODs and VSS values found in the plants.In accordance with GRAU et al. (1975), CECH and CHUDOBA (1983), PITTER and CHUDOBA (1990), CHUDOBA et al (1992), the So/Xo ratio is a fundamental parameter governing the kinetics reactions.Experiments have been conducted under continuous aeration at 20°C where the synthetic wastewater (500 ml) is in contact with activated sludge (200 ml) collected 24 h before and stored at 4°C until the batch is started. In this manner, the initial So is due to the CODs of the synthetic effluent (So eff=197 mg/l) and to the CODs originating from the sludge (5 to 70% of the initial CODs). The initial VSS concentration (Xo) is between 0.6 and 2.5 g/l. Kinetics of CODs removal are simulated by two functions: the first order function, where the initial rate is the maximal, and the sigmoidal function where the maximal rate is reached after a lag time (3 to 8 h).Concerning the first order functions, the degradation rate is faster when the ratio is low (So/Xo lower than 0.44). This is not the case for the sigmoidal functions. In the results of this study, the residual of COD is always lower when the degradation kinetic follows the exponential model.Our experiments show that the type of degradation kinetics (first order or sigmoidal) is not only controlled by the So/Xo parameter but also by the proportion of CODs brought by the sludge and that parameter can play a determinant role.When the proportion of CODs brought by the sludge is very large (between 41% to 46%) the degradation reactions follow the sigmoidal type. These results can possibly be explained by the low biodegradability of the polymers or molecules originating from the inoculum which has been stored during 24 h, or by the low activity of the biomass after 24 h of storage on the biodegradation of the soluble organic matte

Brucella microti: the genome sequence of an emerging pathogen

<p>Abstract</p> <p>Background</p> <p>Using a combination of pyrosequencing and conventional Sanger sequencing, the complete genome sequence of the recently described novel <it>Brucella </it>species, <it>Brucella microti</it>, was determined. <it>B. microti </it>is a member of the genus <it>Brucella </it>within the <it>Alphaproteobacteria</it>, which consists of medically important highly pathogenic facultative intracellular bacteria. In contrast to all other <it>Brucella </it>species, <it>B. microti </it>is a fast growing and biochemically very active microorganism with a phenotype more similar to that of <it>Ochrobactrum</it>, a facultative human pathogen. The atypical phenotype of <it>B. microti </it>prompted us to look for genomic differences compared to other <it>Brucella </it>species and to look for similarities with <it>Ochrobactrum</it>.</p> <p>Results</p> <p>The genome is composed of two circular chromosomes of 2,117,050 and 1,220,319 base pairs. Unexpectedly, we found that the genome sequence of <it>B. microti </it>is almost identical to that of <it>Brucella suis </it>1330 with an overall sequence identity of 99.84% in aligned regions. The most significant structural difference between the two genomes is a bacteriophage-related 11,742 base pairs insert only present in <it>B. microti</it>. However, this insert is unlikely to have any phenotypical consequence. Only four protein coding genes are shared between <it>B. microti </it>and <it>Ochrobactrum anthropi </it>but impaired in other sequenced <it>Brucella</it>. The most noticeable difference between <it>B. microti </it>and other <it>Brucella </it>species was found in the sequence of the 23S ribosomal RNA gene. This unusual variation could have pleiotropic effects and explain the fast growth of <it>B. microti</it>.</p> <p>Conclusion</p> <p>Contrary to expectations from the phenotypic analysis, the genome sequence of <it>B. microti </it>is highly similar to that of known <it>Brucella </it>species, and is remotely related to the one of <it>O. anthropi</it>. How the few differences in gene content between <it>B. microti </it>and <it>B. suis </it>1330 could result in vastly different phenotypes remains to be elucidated. This unexpected finding will complicate the task of identifying virulence determinants in the <it>Brucella </it>genus. The genome sequence of <it>B. microti </it>will serve as a model for differential expression analysis and complementation studies. Our results also raise some concerns about the importance given to phenotypical traits in the definition of bacterial species.</p

Identification of post-transcriptionally regulated Xenopus tropicalis maternal mRNAs by microarray

Cytoplasmic control of the adenylation state of mRNAs is a critical post-transcriptional process involved in the regulation of mRNAs stability and translational efficiency. The early development of Xenopus laevis has been a major model for the study of such regulations. We describe here a microarray analysis to identify mRNAs that are regulated by changes in their adenylation state during oogenesis and early development of the diploid frog Xenopus tropicalis. The microarray data were validated using qRT–PCR and direct analysis of the adenylation state of endogenous maternal mRNAs during the period studied. We identified more than 500 mRNAs regulated at the post-transcriptional level among the 3000 mRNAs potentially detected by the microarray. The mRNAs were classified into nine different adenylation behavior categories. The various adenylation profiles observed during oocyte maturation and early development and the analyses of 3′-untranslated region sequences suggest that previously uncharacterized sequence elements control the adenylation behavior of the newly identified mRNAs. These data should prove useful in identifying mRNAs with important functions during oocyte maturation and early development