Evolution of Microcin V and Colicin Ia Plasmids in Escherichia coli▿

Survey results and genotypic characterization of Escherichia coli strains demonstrate that the bacteriocins colicin Ia and microcin V coassociate in a strain more often than would be expected by chance. When these two bacteriocins co-occur, they are encoded on the same conjugative plasmid. Plasmids encoding colicin Ia and microcin V are nonrandomly distributed with respect to the genomic background of the host strain. Characterization of microcin V and colicin Ia nucleotide variation, together with the backbone of plasmids encoding these bacteriocins, indicates that the association has evolved on multiple occasions and involves the movement of the microcin V operon, together with the genes iroNEDCB and iss, onto a nonrandom subset of colicin Ia plasmids. The fitness advantage conferred on cells encoding both colicin Ia and microcin V has yet to be determined

Tools for high efficiency genetic manipulation of the human pathogen Penicillium marneffei

Penicillium marneffei is an opportunistic pathogen of humans and displays a temperature dependent dimorphic transition. Like many fungi, exogenous DNA introduced by DNA mediated transformation is integrated randomly into the genome resulting in inefficient gene deletion and position-specific effects. To enhance successful gene targeting, the consequences of perturbing components of the non-homologous end joining recombination pathway have been examined. The deletion of the KU70 and LIG4 orthologs, pkuA and ligD, respectively, dramatically enhanced the observed homologous recombination frequency leading to efficient gene deletion. While Δ pkuA was associated with reduced genetic stability over-time, Δ ligD represents a suitable recipient strain for downstream applications and combined with a modified Gateway TM system for the rapid generation of gene deletion constructs, this represents an efficient pipeline for characterizing gene function in P. marneffei. © 2012 Elsevier Inc

MATLAS project - Advanced methods of materials engineering in diagnostics of art works after renovation by means of shaped, high-energy laser radiation pulses

Projekt MATLAS PL0259, realizowany w ramach Mechanizmu Finansowego EOG/Norweskiego Mechanizmu Finansowego, w Obszarze Priorytetowym "Konserwacja Europejskiego Dziedzictwa Kultury", został z powodzeniem rozpoczęty w lipcu 2008 r. Naukowe cele projektu obejmują opracowanie metod diagnostyki powierzchni dzieł sztuki wykonanych z metali (stopów) w celu ich bezpiecznej renowacji laserowej, opracowanie systemu laserowego zdolnego do generacji impulsów o wymaganym w renowacji, kontrolowanym kształcie i czasie trwania oraz analizy zjawisk indukowanych przez impulsy laserowe na powierzchni obiektów historycznych. Artykuł przedstawia uczestniczące w projekcie ośrodki naukowe, projekt i wykonanie laserowego systemu czyszczącego oraz metodykę badań eksperymentalnych. Podsumowuje on również najnowsze wyniki projektu oraz przedstawia metalowe dzieła sztuki wybrane do badań, wraz z ich analizami historycznymi i strukturalnymi.MATLAS project PL0259 successfully started in July 2008 under the EEA Financial Mechanism/ Norwegian Financial Mechanism and in the Key Priority Section "Conservation of European Cultural Heritage". The scientific aims of the project include: development of diagnostic methods for analysis of metal (alloy) artworks surfaces for safe laser renovation; development of a laser system capable of generating pulses with controlled shape and time duration required for renovation, and analysis of phenomena induced by laser pulses in the treated surfaces of historical objects. The paper presents participating scientific teams, design and realization of laser cleaning system and methodology of experimental investigations. It also summarizes the latest project results and presents metal artworks selected for examination with their historical and structural analysis

(100) facets of gamma-Al2O3: The Active Surfaces for Alcohol Dehydration Reactions

Temperature programmed desorption (TPD) of ethanol, as well as ethanol and methanol dehydration reactions were studied on gamma-Al2O3 in order to identify the active catalytic sites for alcohol dehydration reactions. Two high temperature (> 473 K) desorption features were observed following ethanol adsorption. Samples calcined at T a parts per thousand currency sign 473 K displayed a desorption feature in the 523-533 K temperature range, while those calcined at T a parts per thousand yen 673 K showed a single desorption feature at 498 K. These two high temperature desorption features correspond to the exclusive formation of ethylene on the Lewis (498 K) and Bronsted acidic (similar to 525 K) sites. The amount of ethylene formed under conditions where the competition between water and ethanol for adsorption sites is minimized is identical over the two surfaces. Furthermore, a nearly 1-to-1 correlation between the number of under-coordinated Al3+ ions on the (100) facets of gamma-Al2O3 and the number of ethylene molecules formed in the ethanol TPD experiments on samples calcined at T a parts per thousand yen 673 K was found. Titration of the penta-coordinate Al3+ sites on the (100) facets of gamma-Al2O3 by BaO completely eliminated the methanol dehydration reaction activity. These results demonstrate that in alcohol dehydration reactions on gamma-Al2O3, the (100) facets are the active catalytic surfaces. The observed activities can be linked to the same Al3+ ions on both hydrated and dehydrated surfaces: penta-coordinate Al3+ ions (Lewis acid sites), and their corresponding -OH groups (Bronsted acid sites), depending on the calcination temperatureclose363