Comparative genomic analysis of two Chilean Renibacterium salmoninarum isolates and the type strain ATCC 33209T

Indexación: Scopus.Two previously characterized Chilean isolates (H-2 and DJ2R), obtained from cage-cultured Atlantic salmon with clinical signs of bacterial kidney disease in southern Chile, were used (Bethke et al. 2016, 2017). The bacteria were routinely cultured in KDM-2 agar for 15–20 days at 15°C. For sequencing, genomic DNA of the two isolates was extracted using the InstaGene Purification Matrix (Bio-Rad) according to manufacturer instructions. The DJ2R genome was sequenced using an Illumina MiSeq platform with 2 ⨯ 250 paired-end reads by the AUSTRAL-omics Institute, hosted by the Universidad Austral de Chile (Valdivia, Chile). Using the same technology and parameters, H-2 genomic DNA was sequenced by the Central Support Service for Experimental Research (SCSIE, Spanish acronym) at the University of Valencia (Valencia, Spain).This work was supported by funding of the Comisión Nacional de Investigación Científica y Tecnológica (CONICYT, Chile) [Grant Numbers FONDAP No. 15110027 and FONDECYT No. 1150695]. J.B. also acknowledges support received by CONICYT [Doctoral Scholarship No. 21140421].Renibacterium salmoninarum, a slow-growing facultative intracellular pathogen belonging to the high C+G content Actinobacteria phylum, is the causative agent of bacterial kidney disease, a progressive granulomatous infection affecting salmonids worldwide. This Gram-positive bacterium has existed in the Chilean salmonid industry for >30 years, but little or no information is available regarding the virulence mechanisms and genomic characteristics of Chilean isolates. In this study, the genomes of two Chilean isolates (H-2 and DJ2R)were sequenced, and a search was conducted for genes and proteins involved in virulence and pathogenicity, andwecompare with the type strain ATCC 33209T genome. The genome sizes of H-2 and DJ2R are 3,155,332 bp and 3,155,228 bp, respectively. They genomes presented six ribosomal RNA, 46 transcription RNA, and 25 noncodingRNA, and both had the same 56.27% G+C content described for the type strain ATCC 33209 T. A total of 3,522 and 3,527 coding sequences were found for H-2 and DJ2R, respectively. Meanwhile, the ATCC 33209T type strain had 3,519 coding sequences. The in silico genome analysis revealed a genes related to tricarboxylic acid cycle, glycolysis, iron transport and others metabolic pathway. Also, the data indicated that R salmoninarum may have a variety of possible virulence-factor and antibiotic-resistance strategies. Interestingly, many of genes had high identities with Mycobacterium species, a known pathogenic Actin obacteria bacterium. In summary, this study provides the first insights into and initial steps towards understanding the molecular basis of antibiotic resistance, virulence mechanisms and host/environment adaptation in twoChilean R. salmoninarum isolates that contain proteins of which were similar to those of Mycobacterium. Furthermore, important information is presented that could facilitate the development of preventive and treatment measures against R. salmoninarum in Chile and worldwide. © The Author(s) 2018.https://academic.oup.com/gbe/article/10/7/1816/504777

Stress tolerance-related genetic traits of fish pathogen Flavobacterium psychrophilum in a mature biofilm

Indexación: Scopus.Flavobacterium psychrophilum is the causative agent of bacterial cold-water disease and rainbow trout fry syndrome, and hence this bacterium is placed among the most important salmonid pathogens in the freshwater aquaculture industry. Since bacteria in biofilms differ substantially from free-living counterparts, this study sought to find the main differences in gene expression between sessile and planktonic states of F. psychrophilum LM-02-Fp and NCMB1947T, with focus on stress-related changes in gene expression occurring during biofilm formation. To this end, biofilm and planktonic samples were analyzed by RNA sequencing to detect differentially expressed candidate genes (DECGs) between the two growth states, and decreasing the effects of interstrain variation by considering only genes with log2-fold changes ≤ -2 and ≥ 2 at Padj-values = 0.001 as DECGs. Overall, 349 genes accounting for ~15% of total number of genes expressed in transcriptomes of F. psychrophilum LM-02-Fp and NCMB1947T (n = 2327) were DECGs between biofilm and planktonic states. Approximately 83 and 81% of all up- and down-regulated candidate genes in mature biofilms, respectively, were assigned to at least one gene ontology term; these were primarily associated with the molecular function term "catalytic activity." We detected a potential stress response in mature biofilms, characterized by a generalized down-regulation of DECGs with roles in the protein synthesis machinery (n = 63, primarily ribosomal proteins) and energy conservation (seven ATP synthase subunit genes), as well as an up-regulation of DECGs involved in DNA repair (ruvC, recO, phrB1, smf, and dnaQ) and oxidative stress response (cytochrome C peroxidase, probable peroxiredoxin, and a probable thioredoxin). These results support the idea of a strategic trade-offbetween growth-related processes and cell homeostasis to preserve biofilm structure and metabolic functioning. In addition, LDH-based cytotoxicity assays and an intraperitoneal challenge model for rainbow trout fry agreed with the transcriptomic evidence that the ability of F. psychrophilum to form biofilms could contribute to the virulence. Finally, the reported changes in gene expression, as induced by the plankton-to-biofilm transition, represent the first transcriptomic guideline to obtain insights into the F. psychrophilum biofilm lifestyle that could help understand the prevalence of this bacterium in aquaculture settings.https://www.frontiersin.org/articles/10.3389/fmicb.2018.00018/ful

Plasma processes in the preparation of lithium-ion battery electrodes and separators

Abstract: Lithium-ion batteries (LIBs) are the energy storage devices that dominate the portable electronic market. They are now also considered and used for electric vehicles and are foreseen to enable the smart grid. Preparing batteries with high energy and power densities, elevated cycleability and improved safety could be achieved by controlling the microstructure of the electrode materials and the interaction they have with the electrolyte over the working potential window. Selecting appropriate precursors, reducing the preparation steps and selecting more efficient synthesis methods could also significantly reduce the costs of LIB components. Implementing plasma technologies can represent a high capital investment, but the versatility of the technologies allows the preparation of powdered nanoparticles with different morphologies, as well as with carbon and metal oxide coatings. Plasma technologies can also enable the preparation of binder-free thin films and coatings for LIB electrodes, and the treatment of polymeric membranes to be used as separators. This review paper aims at highlighting the different thermal and non-thermal plasma technologies recently used to synthesize coated and non-coated active materials for LIB cathodes and anodes, and to modify the surface of separators

Clinical considerations on the posology of direct oral anticoagulants

Los anticoagulantes dicumarínicos han demostrado su eficacia en pacientes con fibrilación auricular no valvular. Sin embargo, presentan desventajas como la necesidad de ajustar la dosis y la interacción con fármacos y alimentos. Por su parte, los anticoagulantes orales de acción directa se presentan como una alternativa eficaz y segura con un manejo clínico menos complejo. Existe un considerable debate sobre los criterios de selección de las pautas posológicas de los anticoagulantes orales de acción directa. Las diferencias entre ellos y sus pautas de administración han despertado dudas sobre los criterios de selección clínicos, farmacocinéticos y farmacodinámicos que avalan dicha posología. Esta revisión analiza de forma crítica las evidencias disponibles y su impacto en la selección final del esquema posológic

An algebraic approach to the minimum-cost multi-impulse orbit transfer problem

A purely algebraic formulation (i.e., polynomial equations only) of the minimum-cost multi-impulse orbit-transfer problem without time constraints is presented, while keeping all the variables with a precise physical meaning. General algebraic techniques are applied to solve these equations (resultants, Gröbner bases, etc.) in several situations of practical interest of different degrees of generality. For instance, a proof of the optimality of the Hohmann transfer for the minimum-fuel two-impulse circular-to-circular orbit-transfer problem is provided. Finally, a general formula is also provided for the optimal two-impulse in-plane transfer between two rotated elliptical orbits under a mild symmetry assumption on the two points where the impulses are applied (which, it is conjectured, can be removed)