La fonction de partition de Minc et une conjecture de Segal pour certains spectres de Thom

On construit dans cet article une résolution injective minimale dans la catégorie \U des modules instables sur l'algèbre de Steenrod modulo $2$, de la cohomologie de certains spectres obtenus à partir de l'espace de Thom du fibré, associé à la représentation régulière réduite du groupe abélien élémentaire $(\Z/2)^n$, au dessus de l'espace $B(\Z/2)^n$. Les termes de la résolution sont des produits tensoriels de modules de Brown-Gitler $J(k)$ et de modules de Steinberg $L_n$ introduits par S. Mitchell et S. Priddy. Ces modules sont injectifs d'après J. Lannes et S. Zarati, de plus ils sont indécomposables. L'existence de cette résolution avait été conjecturée par Jean Lannes et le deuxième auteur. La principale indication soutenant cette conjecture était un résultat combinatoire de G. Andrews : la somme alternée des séries de Poincaré des modules considérées est nulle

A simple, effective, green method for regioselective 3-acylation of unprotected indoles

A fast and green method is developed for regioselective acylation of indoles in the 3-position without the need for protection of the NH position. The method is based on Friedel-Crafts acylation using acid anhydrides. The method has been optimized, and Y(OTf)3 in catalytic amounts is found to be the best catalyst together with the commercially available ionic liquid [BMI]BF4 (1-butyl-3-methylimidazolium tetrafluoro-borate) as solvent. The reaction is completed in a very short time using monomode microwave irradiation. The catalyst can be reused up to four times without significant loss of activity. A range of substituted indoles are investigated as substrates, and thirteen new compounds have been synthesized

Development of freshwater prawn (Macrobrachium rosenbergii) seed production and culture technology in the Mekong Delta Region of Vietnam: A review of the JIRCAS Project at Cantho University.

The Mekong Delta of Vietnam is a region rich in aquatic resources having high potential for aquaculture development. Inland aquaculture in the Mekong Delta has greatly increased since the last decade. Fish culture carried out in combination with other agricultural activities such as animal husbandry and rice cultivation, and intensive aquaculture in ponds and cages have been the dominant forms of fish production. However, the giant freshwater prawn, Macrobrachium rosenbergii, has recently become a species of economic significance and the target of aquaculture activity in the Mekong Delta. M. rosenbergii is cultured throughout the region in the rice fields, ponds, orchard gardens and in pens along river banks. The major constraints in this industry are seed supply and culture techniques, becoming the major obstacles for the further development of the culture of this species. In a collaborative research project implemented between the Japan International Research Center for Agricultural Sciences (JIRCAS) and Cantho University (CTU) since 1994, studies have been carried out on various aspects relating to the establishment of M. rosenbergii seed production and culture technology. The project is now in the middle of its second phase and has generated a great deal of scientific and practical information. This paper presents an overview of the achievements of this project

Titanium dioxide - activated carbon composite for photoelectrochemical degradation of phenol

In this study, titanium dioxide (TiO2) and titanium dioxide – activated carbon composite (TiO2–AC) were prepared by sol-gel method for photoelectrochemical (PEC) applications. Characterization of the materials was performed by scanning electron microscope, energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, X-ray diffraction, and diffuse reflectance spectroscopy. The results show that TiO2 was successfully loaded on activated carbon (AC), producing TiO2–AC with 2.61 eV of bandgap energy, lower than that of TiO2 (3.15 eV). Photoanodes based on TiO2 and TiO2–AC were fabricated and applied to PEC experiments for phenol degradation. In comparison with the TiO2 photoanode, the TiO2–AC one exhibited superior photocatalytic activity, which was indicated by a high current density and effective phenol removal. A mechanism of phenol PEC degradation on the TiO2–AC photoanode was proposed, which includes interaction between protonated phenol and active sites bearing oxygen on the photoanode surface. A kinetic model according to this mechanism was also established and fitted to experimental findings, resulting in rate constants of elementary reactions

Metabolic and evolutionary patterns in the extremely acidophilic archaeon Ferroplasma acidiphilum YT

Ferroplasmaceae represent ubiquitous iron-oxidising extreme acidophiles with a number of unique physiological traits. In a genome-based study of Ferroplasma acidiphilum YT, the only species of the genus Ferroplasma with a validly published name, we assessed its central metabolism and genome stability during a long-term cultivation experiment. Consistently with physiology, the genome analysis points to F. acidiphilum YT having an obligate peptidolytic oligotrophic lifestyle alongside with anaplerotic carbon assimilation. This narrow trophic specialisation abridges the sugar uptake, although all genes for glycolysis and gluconeogenesis, including bifunctional unidirectional fructose 1,6-bisphosphate aldolase/phosphatase, have been identified. Pyruvate and 2-oxoglutarate dehydrogenases are substituted by ‘ancient’ CoA-dependent pyruvate and alpha-ketoglutarate ferredoxin oxidoreductases. In the lab culture, after ~550 generations, the strain exhibited the mutation rate of ≥1.3 × 10−8 single nucleotide substitutions per site per generation, which is among the highest values recorded for unicellular organisms. All but one base substitutions were G:C to A:T, their distribution between coding and non-coding regions and synonymous-to-non-synonymous mutation ratios suggest the neutral drift being a prevalent mode in genome evolution in the lab culture. Mutations in nature seem to occur with lower frequencies, as suggested by a remarkable genomic conservation in F. acidiphilum YT variants from geographically distant populations

Conversion of Uric Acid into Ammonium in Oil-Degrading Marine Microbial Communities: a Possible Role of Halomonads

Uric acid is a promising hydrophobic nitrogen source for biostimulation of microbial activities in oil-impacted marine environments. This study investigated metabolic processes and microbial community changes in a series of microcosms using sediment from the Mediterranean and the Red Sea amended with ammonium and uric acid. Respiration, emulsification, ammonium and protein concentration measurements suggested a rapid production of ammonium from uric acid accompanied by the development of microbial communities containing hydrocarbonoclastic bacteria after 3 weeks of incubation. About 80 % of uric acid was converted to ammonium within the first few days of the experiment. Microbial population dynamics were investigated by Ribosomal Intergenic Spacer Analysis and Illumina sequencing as well as by culture-based techniques. Resulting data indicated that strains related to Halomonas spp. converted uric acid into ammonium, which stimulated growth of microbial consortia dominated by Alcanivorax spp. and Pseudomonas spp. Several strains of Halomonas spp. were isolated on uric acid as the sole carbon source showed location specificity. These results point towards a possible role of halomonads in the conversion of uric acid to ammonium utilized by hydrocarbonoclastic bacteria.With exception of XH and JC, all authors were supported by the FP7 Project ULIXES (FP7-KBBE-2010-266473). This work was further funded by grant BIO2011-25012 from the Spanish Ministry of the Economy and Competitiveness. FM was supported by Università degli Studi di Milano, European Social Fund (FSE) and Regione Lombardia (contract BDote Ricerca^). DD acknowledges support of KAUST, King Abdullah University of Science and Technology. PG acknowledges the support of the European Commission through the project Kill-Spill (FP7, Contract Nr 312139).Peer Reviewe

Bioprospecting reveals class III ω-transaminases converting bulky ketones and environmentally relevant polyamines

Amination of bulky ketones, particularly in (R) configuration, is an attractive chemical conversion; however, known ω-transaminases (ω-TAs) show insufficient levels of performance. By applying two screening methods, we discovered 10 amine transaminases from the class III ω-TA family that were 38% to 76% identical to homologues. We present examples of such enzymes preferring bulky ketones over keto acids and aldehydes with stringent (S) selectivity. We also report representatives from the class III ω-TAs capable of converting (R) and (S) amines and bulky ketones and one that can convert amines with longer alkyl substituents. The preference for bulky ketones was associated with the presence of a hairpin region proximal to the conserved Arg414 and residues conforming and close to it. The outward orientation of Arg414 additionally favored the conversion of (R) amines. This configuration was also found to favor the utilization of putrescine as an amine donor, so that class III ω-TAs with Arg414 in outward orientation may participate in vivo in the catabolism of putrescine. The positioning of the conserved Ser231 also contributes to the preference for amines with longer alkyl substituents. Optimal temperatures for activity ranged from 45 to 65°C, and a few enzymes retained ≥50% of their activity in water-soluble solvents (up to 50% [vol/vol]). Hence, our results will pave the way to design, in the future, new class III ω-TAs converting bulky ketones and (R) amines for the production of high-value products and to screen for those converting putrescine

Multilocus sequence typing of Cryptococcus neoformans var. grubii from Laos in a regional and global context.

Cryptococcosis causes approximately 180 000 deaths each year in patients with human immunodeficiency virus (HIV). Patients with other forms of immunosuppression are also at risk, and disease is increasingly recognized in apparently immunocompetent individuals. Cryptococcus neoformans var. grubii, responsible for the majority of cases, is distributed globally. We used the consensus ISHAM Multilocus sequence typing (MLST) scheme to define the population structure of clinical C. neoformans var. grubii isolates from Laos (n = 81), which we placed into the global context using published MLST data from other countries (total N = 1047), including a reanalysis of 136 Vietnamese isolates previously reported. We observed a phylogeographical relationship in which the Laotian population was similar to its neighbor Thailand, being dominated (83%) by Sequence Types (ST) 4 and 6. This phylogeographical structure changed moving eastwards, with Vietnam's population consisting of an admixture of isolates dominated by the ST4/ST6 (35%) and ST5 (48%) lineages. The ST5 lineage is the predominant ST reported from China and East Asia, where it accounts for >90% of isolates. Analysis of genetic distance (Fst) between different populations of C. neoformans var. grubii supports this intermediate structure of the Vietnamese population. The pathogen and host diversity reported from Vietnam provide the strongest epidemiological evidence of the association between ST5 and HIV-uninfected patients. Regional anthropological genetic distances suggest diversity in the C. neoformans var. grubii population across Southeast Asia is driven by ecological rather than human host factors. Where the ST5 lineage is present, disease in HIV-uninfected patients is to be expected

Screening and Characterization of Novel Polyesterases from Environmental Metagenomes with High Hydrolytic Activity against Synthetic Polyesters

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