Identification and characterization of the dif Site from Bacillus subtilis

Bacteria with circular chromosomes have evolved systems that ensure multimeric chromosomes, formed by homologous recombination between sister chromosomes during DNA replication, are resolved to monomers prior to cell division. The chromosome dimer resolution process in Escherichia coli is mediated by two tyrosine family site-specific recombinases, XerC and XerD, and requires septal localization of the division protein FtsK. The Xer recombinases act near the terminus of chromosome replication at a site known as dif (Ecdif). In Bacillus subtilis the RipX and CodV site-specific recombinases have been implicated in an analogous reaction. We present here genetic and biochemical evidence that a 28-bp sequence of DNA (Bsdif), lying 6° counterclockwise from the B. subtilis terminus of replication (172°), is the site at which RipX and CodV catalyze site-specific recombination reactions required for normal chromosome partitioning. Bsdif in vivo recombination did not require the B. subtilis FtsK homologues, SpoIIIE and YtpT. We also show that the presence or absence of the B. subtilis SPβ-bacteriophage, and in particular its yopP gene product, appears to strongly modulate the extent of the partitioning defects seen in codV strains and, to a lesser extent, those seen in ripX and dif strains

FLOSS in an industrial economics perspective

National audienceThe spread of free/libre open source software (FLOSS) represents one of the most important developments in the Information Technology (IT) industry in recent years. Within the context of a knowledge-based economy, this sort of approach appears exemplary for a growing number of industrial activities in which the amount of knowledge that has to be mastered is too large for a single agent, however powerful. Considering knowledge as a mutual resource requires a rethinking of the value chain concept, since cash flow is derived from use of the knowledge base (services, complementary products), not from the knowledge itself. In a classical industrial economics perspective, this reshaping of the value chain must be analyzed not only at the global ecosystem level (who produces what, between firms and universities, users and producers, etc.), but also at the industry level (once the industrys role has been identified, how does it organize itself?). Various points of view have been proposed, but researchers have generally studied either the involvement of firms in a community or the integration of FLOSS into their market strategy, but not both. In this article, we argue for a more structured and global analysis, based on the tools of industrial economics, and thus starting from the basic conditions of the computer market and of the buyers competence in software development (the dominant users skill). This conceptual framework helps to distinguish the different types of corporate behavior we see in the FLOSS ecosystem and more specifically their varying degrees of involvement.Ces dernières années, la diffusion du logiciel libre, ou open source, représente une des évolutions les plus importantes de l’industrie des technologies de l’information. Dans un contexte d’une économie basée sur la connaissance, ce modèle apparaît comme exemplaire pour de nombreuses industries, où la quantité de connaissance qu’il faut maîtriser est trop grande pour être maîtrisée par un seul agent, même puissant. Considérer la connaissance comme une ressource partagée implique de repenser le concept de chaîne de valeur, car la richesse est générée par les usages de cette base de connaissance (services, produits complémentaires) et non plus de la connaissance par elle-même. Si l’on se place dans une perspective d’économie industrielle « classique », cette restructuration de la valeur doit être étudiée au niveau de l’écosystème global (qui produit quoi entre les entreprises et les universités, entre les utilisateurs et les producteurs, etc.), mais aussi au niveau industriel (une fois que le rôle de l’industrie est compris, comment celle-ci s’organise). De nombreuses explications ont été proposées, mais, la plupart du temps, les chercheurs étudient soit l’implication des entreprises dans les communautés, soit l’intégration du logiciel libre dans leurs stratégies commerciales, rarement les deux. Dans cet article, nous défendons l’idée d’une approche plus structurée et globale, partant des conditions initiales du marché de l’informatique et des compétences des acheteurs en terme de développement logiciel (les compétences de l’utilisateur « représentatif »). Ce cadre conceptuel permet d’éclairer les différents comportements des entreprises que l’on constate dans l’écosystème libre, et spécifiquement la variation de leur implication

Jean Prouvé and Konrad Wachsmann. Two Ways of Using the Scale Model as a Tool for Projecting

Jean Prouvé y Konrad Wachsmann pertenecieron a una época convulsa en la que los ideales de la arquitectura se vieron modificados y nuevas variables entraron en juego. La dimensión técnico–constructiva recuperó protagonismo a su vez que la industrialización comenzó a influenciar en las construcciones del momento caracterizadas por su expresión tectónica. Maquetas a escala, así como prototipos de tamaño real, fueron utilizadas por Prouvé y Wachsmann como una herramienta fundamental en el proceso creativo. El presente artículo analiza las diferencias en el empleo de la maqueta y las estrategias de proyecto utilizadas por ambos arquitectos a través del análisis de dos obras, el Aeroclub de Roland Garros (1935) de Jean Prouvé y el Mobilar Structure (1939) de Konrad Wachsmann.Jean Prouvé and Konrad Wachsmann belonged to a convulsive period in which the ideals of architecture were modified and new variables came into play. The technique–constructive dimension regained prominence at a time when industrialization began to influence the constructions of that time, characterised by their tectonic expression. Together with real–size prototypes, Prouvé and Wachsmann employed scale models as fundamental tools in their creative process. This article explores the differences in the use of the model and projecting strategies through the analysis of two works: the Roland Garros flying club (1935) by Jean Prouvé and Mobilar Structure (1939) by Konrad Wachsmann

Net Zero Residential Design for Solar CalPoly

The Department of Energy (DOE) confirmed Team Solar Cal Poly from California Polytechnic State University, San Luis Obispo, as a competitor in the 2015 Solar Decathlon in February 2014. The Solar Decathlon is a biennial collegiate competition to construct a net-zero home and operate it for a week of “normal use”. Solar Cal Poly needed assistance with passive and active HVAC systems for the design, and thermal load models. The competition will take place in Irvine, CA [33.67⁰, 117.82⁰ W] from September 27 – October 3, 2015. After the completion, a potential final location for the house will be Santa Ynez, CA [34.61⁰ N, 120.09⁰ W]. Ms. Willis assisted with a climate study for both locations and research passive and active HVAC systems and design elements for Team Solar Cal Poly. She modeled the final summer design in DesignBuilder to calculate the heating and cooling loads. The heating load was calculated to be 26.7 kBTU/h. The cooling load was calculated to be 2-tons. A mini-split HVAC system was selected for the final summer design based off the calculated heating and cooling loads. For this design, the Fujitsu Hybrid Halcyon Flex met the minimum requirements, and was a multi-zone system that could condition all three major spaces of the design. This report provides a summary of information and the basic design process for future Solar Decathlon designs considerations

Alcayota Gum Films: Experimental Reviews

Polysaccharides obtained from plant have been investigated for the develop-ment of edible/biodegradable non petrochemical-based packaging materials. Alcayota (Curcubita ficifolia) is the fruit of a creeping plant such as waterme-lon and melon. It is the fruit of a creeping plant such as watermelon and me-lon. After separating the pulp from the husk and seeds it is dried and ground to obtain a flour. Different alcayota flour is made to hydrolyze then. Alkaline hydrolysis is released to extraction of alcayota gum and is purified by hy-droalcoholic solutions. The films were prepared from water solution of hy-drolyzed alcayota gum (AlcOH). AlcOH film present properties are mainly due to the strong hydrophilicity. In order to improve water resistance, the films were modified using glutaraldehyde (Glu), in order to make the water insoluble film. The crosslinked films providing a low water vapor permeability (WVP) and high mechanical properties expressed in elastic modulus. The X-ray diffraction showed amorphous and shift to lower dspacing, i.e. at lower distances between the polysaccharide chains. These crosslinked membranes exhibit excellent water resistance, low O2 permeation, which make them very useful in selecting biodegradable polymer and films.Fil: Zanon, Marisa. Universidad Nacional de San Luis; ArgentinaFil: Masuelli, Martin Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; Argentin

The Second Conference on Lunar Bases and Space Activities of the 21st Century, volume 1

These papers comprise a peer-review selection of presentations by authors from NASA, LPI industry, and academia at the Second Conference (April 1988) on Lunar Bases and Space Activities of the 21st Century, sponsored by the NASA Office of Exploration and the Lunar Planetary Institute. These papers go into more technical depth than did those published from the first NASA-sponsored symposium on the topic, held in 1984. Session topics covered by this volume include (1) design and operation of transportation systems to, in orbit around, and on the Moon, (2) lunar base site selection, (3) design, architecture, construction, and operation of lunar bases and human habitats, and (4) lunar-based scientific research and experimentation in astronomy, exobiology, and lunar geology

Physical and antimicrobial properties of biofilms containing natural antimicrobial agents

Thesis (Master)--Izmir Institute of Technology, Biotechnology, Izmir, 2008Includes bibliographical references (leaves: 83-94)Text in English; Abstract: Turkish and Englishxii, 94 leavesThe goal of this study is to evaluate physical and antimicrobial properties of biopolymers prepared from gluten (WG) and methyl cellulose (MC) with incorporation of activated lactoferrin (ALF), rosemary extract (RE) and natamycin (NA). The effectiveness of agents and antimicrobial films were investigated by agar disc diffusion method. Mechanical and water vapor permeability (WVP) of antimicrobial films were also examined. Film structure was investigated by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). Application of films was studied on Kashar cheese inoculated with target molds during 30 days storage at 10oC.ALF and RE did not show inhibitory activity against tested microorganisms.Minimum inhibitory concentration (MIC) of NA was found 750 ppm against Aspergillus niger and Penicillium roquefortii. Both films containing NA showed antifungal activity concentrations at and above 2 and 1 mg NA/10 g film solution (fs) against A. niger and P. roquefortii, respectively. RE in combination with NA reduced MIC of NA against A. niger to 1.5 mg NA/10g fs in both films. FTIR spectroscopy did not indicate any interaction between NA and both films. SEM observations showed that NA crystallizes at high concentrations in biopolymers. There was no significant change in WVP of films containing NA. Incorporation of NA to WG film did not cause major changes in its mechanical properties. Reduction in tensile strength of MC films was observed at high NA concentration. Application studies demonstrated the efficacy of WG and MC films including NA against A. niger and P.roquefortii inoculated on Kashar cheese

Starch-protein active films for food preservation

Tesis por compendioThe overall objective of the doctoral thesis was the development of starch-based (S) biodegradable active films for food packaging applications, by applying both casting method and thermoprocessing. Different blends of S with protein material have been studied in order to improve the functional properties of the films or confer antimicrobial/antioxidant activity. The following protein materials were used: powder buttermilk (BM); lactoferrin (LF) and/or lysozyme (LZ), and bovine gelatin (BG). Ethyl lauroyl arginate (LAE, E243) was also incorporated as antimicrobial compound. Likewise, S:BG blend films, either with or without LAE, with previously oxidized S, have been studied to enhance the crosslinking of polymer chains and to improve the film properties. The films have been characterized as to their functional properties as packaging material, their antioxidant and/or antimicrobial properties, as well as their capacity for preserving different food systems, in terms of lipid oxidation and microbial spoilage. Blends of S with BM gave rise to films with a heterogeneous structure, in which the formation of a protein gel was observed when BM dispersion was heated with S at 90 ºC for 30 min. The heat treatment promoted an increase in the resistance to break and stretchability of films, together with a decrease in water vapour permeability. Only those films subjected to heat treatment exhibited antioxidant activity, probably due to the release of active peptides as a result of high temperatures. However, no antilisterial activity was observed for any film containing BM. The incorporation of LF and/or LZ into S films, obtained by the casting method, led to a partial compatibility between polymers, thus affecting the microstructure of S films, as well as leading to an rise in the glass transition temperature. Films with proteins were less extensible, especially when LF was incorporated. All of the films tested were effective at controlling the progress of lipid oxidation in pork lard, whereas only films with LF/LZ blend reduced the growth of coliforms in minced pork meat, as a result of their synergistic action. Films based on S and BG blends (1:1) were obtained by both casting method and thermo-processing. Phase separation of both polymers (stratified structure or separated domains of both polymers, respectively) was observed in both cases. The incorporation of LZ, but mainly LAE, into films, enhanced the compatibility between polymers. Thermo-processed films were more permeable to water vapour and oxygen, less rigid and resistant and more stretchable, in comparison with those films obtained by casting. While LAE incorporation improved the water vapour barrier capacity, it worsened the oxygen barrier properties, contrary to the effect produced by LZ. All films with LAE exhibited high antilisterial activity. Films based on oxidized S and BG (1:1), obtained by casting, showed a high polymer compatibility, and crosslinking between the polymer chains occurred due to the carbonyl-amino condensation reaction. As a result, the water uptake ability of the films decreased and the mechanical and barrier properties improved, although film browning was induced due to the formation of Maillard compounds. LAE incorporation implied its involvement in condensation reactions, due to its bi-functional character (carbonyl-amino), thus affecting crosslinking and the film properties. These reactive processes progressed throughout storage time, leading to an increase in the mechanical resistance and browning of the films. The obtained Maillard compounds conferred antimicrobial capacity on the films, which increased as the storage time progressed. The application of blend films of native or oxidized S and BG with LAE, for the purposes of preserving vacuum packaged chicken breast fillets, extended the shelf-life through the inhibition of bacterial growth (total viable counts; psicrotrophic, anaerobic,lactic acid bacteria and coliforms). Samples packaged iEl objetivo general de la presente tesis doctoral se basa en el desarrollo de films activos biodegradables a base de almidón (S) para su aplicación en sistemas de envasado de alimentos, por medio de dos métodos diferentes de obtención, método en húmedo por extensión y secado (casting) y método en seco (termoprocesado). Se estudiaron mezclas de S con diferentes materiales proteicos, con fin de disminuir la alta higroscopicidad de los films de S y su retrogradación a lo largo del tiempo de almacenamiento y mejorar sus propiedades funcionales, así como conferirles actividad antimicrobiana/antioxidante. Los materiales proteicos utilizados fueron los siguientes: suero de mantequilla en polvo (BM); lactoferrina (LF) y/o lisozima (LZ), y gelatina bovina (BG). El etil lauroil arginato (LAE, E243) fue también incorporado como compuesto antimicrobiano. Asimismo, se estudiaron los films mezcla de S con BG, con y sin LAE incorporado, habiendo oxidado previamente el S, para así potenciar el entrecruzado de las cadenas poliméricas y mejorar las propiedades de los films. Estos fueron caracterizados en sus propiedades funcionales como material de envase, sus propiedades antioxidantes y/o antimicrobianas, así como por su capacidad de conservación de diferentes sistemas alimentarios, en términos de su oxidación lipídica y deterioro microbiológico. Las mezclas de S con BM dieron lugar a películas con una estructura heterogénea, en las que se observó la formación de un gel proteico como resultado del calentamiento de la dispersión BM con S a 90 ºC durante 30 min. El tratamiento térmico promovió un aumento de la resistencia a la rotura y extensibilidad de los films, junto con una disminución en la permeabilidad al vapor de agua. Sólo las películas sometidas a tratamiento térmico y homogeneización con cizalla mostraron actividad antioxidante, probablemente debido a la liberación de péptidos activos en consecuencia de la alta temperatura y fuerza de cizalla aplicada Sin embargo, no se observó actividad antilisteria para ninguno de los films con BM. La incorporación de LF y/o LZ en films de S condujo a una compatibilidad parcial entre polímeros, afectando así a la microestructura de los films de S, y produciendo un aumento de la temperatura de transición vítrea y disminución de la capacidad de alargamiento de los films, especialmente cuando se incorporó LF. Todos los films resultaron eficaces en el control del progreso de la oxidación lipídica de la manteca de cerdo, mientras que sólo las películas con mezcla LF/LZ redujeron el crecimiento de coliformes en carne picada de cerdo, como resultado de su acción sinérgica. Los films basados en la mezcla S y BG (1: 1) fueron obtenidos por casting y termo-moldeado y compresión, llevando a la separación de fases entre ambos polímeros (estructura esratificada o separación de dominios de ambos polímeros, respectivamente). La incorporación de LZ, y principalmente de LAE, en los films, aumentó la compatibilidad entre ambos polímeros. Los films termoprensados fueron más permeables al vapor de agua y al oxígeno, menos rígidos y resistentes y más extensibles, en comparación con aquellos obtenidos por casting. La incorporación de LAE mejoró la capacidad de barrera contra el vapor de agua, mientras que incurrió en un empeoramiento de la barrera frente al oxígeno, contrariamente al efecto producido por la LZ. Los films con LAE, moldeados o termoprensados, mostraron una alta eficacia antilisteria. Los films basados en S oxidado y BG (1: 1), fueron obtenidos por casting y mostraron una alta compatibilidad polimérica, lo cual condujo al entrecruzado de las cadenas como resultado de la reacción de condensación carbonilo-amino producida entre ambos polímeros. En consecuencia, la capacidad de absorción de agua de los films disminuyó y se mejoraron las propiedades mecánicas y de barrera, aunque también se indujo a un pardeamiento de los films, indicandoL'objectiu general de la tesi doctoral és el desenvolupament de films actius biodegradables a base de midó (S) per a la seua aplicació en sistemes d'envasat d'aliments, amb l'utitització del mètode d'extensió i assecat (casting) i termoprocessat (barrejat en fos i termo-compressió). Es van estudiar barreges de S amb diferents materials proteics, per millorar les propietats funcionals dels films o conferir activitat antimicrobiana. Els materials protèics utilitzats van ser: sèrum de mantega en pols (BM); lactoferrina (LF) i/o lisozima (LZ), i gelatina bovina (BG). L'ètil lauroil arginat (LAE, E243) va ser també incorporat com a compost antimicrobià. Així mateix, es van estudiar els films barreja de S amb BG, amb i sense LAE, havent oxidat prèviament el S, per potenciar l'entrecreuat de les cadenes polimèriques i millorar les propietats dels films. Aquests van ser caracteritzats en les seues propietats funcionals com a material d'envàs, les seues propietats antioxidants i/o antimicrobianes, així com en la seua capacitat de conservació en diferents sistemes alimentaris, en termes de la seua oxidació lipídica i deteriorament microbià. Les barreges de S amb BM van donar lloc a films amb una estructura heterogènia, en què es va observar la formació d'un gel protèic com a resultat del calfament de la dispersió BM amb S a 90 ºC durant 30 min. El tractament tèrmic va promoure un augment de la resistència al trencament i extensibilitat dels films, juntament amb una disminució en la permeabilitat al vapor d'aigua. Només el films sotmesos a tractament tèrmic van mostrar activitat antioxidant, probablement a causa de l'alliberament de pèptids actius com a conseqüència de l'alta temperatura. No obstant això, no es va observar activitat antilisteria per cap dels films amb BM. La incorporació de LF i/o LZ en films de S obtinguts per casting va donar lloc a una compatibilitat parcial entre polímers, afectant a la microestructura dels films de S, i produint un augment de la temperatura de transició vítria. Els films amb les proteïnes van ser menys extensibles, especialment quan es va incorporar LF. Tots els films van resultar eficaços en el control de l'oxidació lipídica de la mantega de porc, mentre que només el films amb barreja LF/LZ van reduir el creixement de coliforms en carn picada de porc, com a resultat de la seua acció sinèrgica. Els films amb barreges S i BG (1: 1) van ser obtinguts per casting i termo-processat. En tots dos casos es va observar separació de fases entre els dos polímers (estructura estratificada o separació de dominis d'ambdós polímers, respectivament). La incorporació de LZ, i principalment de LAE, en els films, va augmentar la compatibilitat entre tots dos polímers. Els films termo-processats van ser més permeables al vapor d'aigua i l'oxigen, menys rígids i resistents i més extensibles, en comparació amb els obtinguts per càsting. La incorporació de LAE va millorar la capacitat de barrera al vapor d'aigua, a l'hora que va disminuir la capacitat de barrera davant l'oxigen, contràriament a l'efecte produït per la LZ. Tots els films amb LAE, van mostrar una alta capacitat antilisteria. Els films amb S oxidat i BG (1: 1), van ser obtinguts per casting i van mostrar una alta compatibilitat dels polímers, tot produint entrecreuat de les cadenes com a resultat de la reacció de condensació carbonil-amino. En conseqüència, va disminuir la capacitat d'absorció d'aigua dels films i es van millorar les propietats mecàniques i de barrera, encara que es va promoure l'enfosquiment dels films, cosa que indica la formació de compostos de Maillard. La incorporació de LAE va implicar la seua participació en les reaccions de condensació, a causa del seu caràcter bi-funcional (carbonil-amino), el que va afectar a l'entrecreuat i les propietats dels films. Aquests processos reactius van progressar al llarg del temps d'emmagatzematge, donant lloc a un augment de lMoreno Marro, O. (2017). Starch-protein active films for food preservation [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/80616TESISCompendi

Nature and modulation of the higher order chromatin fibre

The bulk of eukaryotic cellular DNA is compacted into chromatin, a nucleoprotein complex that is responsible for packaging DNA into the nucleus and regulating gene transcription. The chromatin fibre is a dynamic structure which is able to accommodate the many complex processes which occur simultaneously in a living cell. The fundamental building blocks of the lower order chromatin fibre have been studied extensively, providing us with a detailed understanding of the structures present; much is known about how these structures are modulated to allow processes like gene transcription and replication to occur in an organised fashion. In contrast to our detailed knowledge of the fundamental building blocks of chromatin, little is known about the conformation of the higher order chromatin fibre. This lack of understanding is due, predominantly, to the inaccessibility of the higher order fibre for study, and that much of the research to date has considered the conformation of the higher order fibre to be uniform. In this project I have analysed and modulated the higher order chromatin fibre to assess the role this fibre plays in the regulation of cellular processes.The conformation of the higher order chromatin fibre is often thought to change during the differentiation of cells. To study this alteration in conformation I have undertaken a detailed analysis of the higher order chromatin fibre from cells with different differentiation potentials and during their differentiation process. Using a hydrodynamic sedimentation approach to assess the conformation of the chromatin fibre I was unable to find any differences in its conformation. However, I have found that these chromatin fibres do have inherent differences in their nuclease sensitivities, suggesting that although the overall conformation of the fibres are similar, there are chromatin- related differences between cells with various differentiation potentials.To study the uniformity of the higher order chromatin fibre at different chromosomal locations I have analysed the chromatin structure found at centromeres to determine whether there is an alteration in the conformation of the chromatin fibre, which might affect the function of centromeres. My results clearly show that in mouse and human cells the chromatin fibre found at inner centromeric regions is more compact than the chromatin fibre present at outer centromeric regions, and in turn this is more compact than the bulk chromatin fibre. To determine the molecular basis for this, I have analysed acetylated centromeric heterochromatin from embryonic stem (ES) cells and heterochromatin associated with undermethylated centromeric DNA from F9 cells. My results demonstrate that this special chromatin architecture found at centromeres appears to be independent of histone acetylation and DNA methylation.To establish whether an alteration in the chromatin conformation will alter a cell's differentiation potential I have expressed histone H5, a replacement linker histone normally found in nucleated erythrocytes, in pluripotential ES cells. My results show that the constitutive expression of H5 in ES cells causes substantial cell death. I have therefore constructed a regulated, tetracycline based, histone H5 expression system in ES cells, but I was unable to express H5 in a controlled manner to investigate the underlying chromatin structure of these cells. In addition, I expressed histone H5 DNA -binding mutants in ES cells which also caused substantial cell death. I was therefore unable to determine whether the cellular phenotype obtained from expressing H5 in ES cells was due to an alteration in chromatin structure or a non- specific effect from expressing a positively charged molecule. As a first step towards studying the expression of linker histones in living cells and during development, I constructed and analysed a green fluorescent protein (GFP)- histone H5 fusion. As for histone H5, the GFP -H5 fusion protein is correctly expressed in a variety of cell types, but is lethal to cells when expressed at high levels for longer periods of time

Mustang Daily, Poly Royal Special Edition Section II, April 22, 1977

Student newspaper of California Polytechnic State University, San Luis Obispo, CA.https://digitalcommons.calpoly.edu/studentnewspaper/3557/thumbnail.jp