Characterization of a novel Lactobacillus species closely related to Lactobacillus johnsonii using a combination of molecular and comparative genomics methods

<p>Abstract</p> <p>Background</p> <p>Comparative genomic hybridization (CGH) constitutes a powerful tool for identification and characterization of bacterial strains. In this study we have applied this technique for the characterization of a number of <it>Lactobacillus </it>strains isolated from the intestinal content of rats fed with a diet supplemented with sorbitol.</p> <p>Results</p> <p>Phylogenetic analysis based on 16S rRNA gene, <it>recA</it>, <it>pheS</it>, <it>pyrG </it>and <it>tuf </it>sequences identified five bacterial strains isolated from the intestinal content of rats as belonging to the recently described <it>Lactobacillus taiwanensis </it>species. DNA-DNA hybridization experiments confirmed that these five strains are distinct but closely related to <it>Lactobacillus johnsonii </it>and <it>Lactobacillus gasseri</it>. A whole genome DNA microarray designed for the probiotic <it>L. johnsonii </it>strain NCC533 was used for CGH analysis of <it>L. johnsonii </it>ATCC 33200^T, <it>L. johnsonii </it>BL261, <it>L. gasseri </it>ATCC 33323^Tand <it>L. taiwanensis </it>BL263. In these experiments, the fluorescence ratio distributions obtained with <it>L. taiwanensis </it>and <it>L. gasseri </it>showed characteristic inter-species profiles. The percentage of conserved <it>L. johnsonii </it>NCC533 genes was about 83% in the <it>L. johnsonii </it>strains comparisons and decreased to 51% and 47% for <it>L. taiwanensis </it>and <it>L. gasseri</it>, respectively. These results confirmed the separate status of <it>L. taiwanensis </it>from <it>L. johnsonii </it>at the level of species, and also that <it>L. taiwanensis </it>is closer to <it>L. johnsonii </it>than <it>L. gasseri </it>is to <it>L. johnsonii</it>.</p> <p>Conclusion</p> <p>Conventional taxonomic analyses and microarray-based CGH analysis have been used for the identification and characterization of the newly species <it>L. taiwanensis</it>. The microarray-based CGH technology has been shown as a remarkable tool for the identification and fine discrimination between phylogenetically close species, and additionally provided insight into the adaptation of the strain <it>L. taiwanensis </it>BL263 to its ecological niche.</p

pVHL-mediated regulation of the anti-angiogenic protein thrombospondin-1 decreases migration of Clear Cell Renal Carcinoma Cell Lines

Thrombospondin-1 (TSP-1) is a multifunctional matrix protein with antitumor activities due in part to its ability to inhibit angiogenesis, which in turn contributes to determine the fate of many tumours. Previous studies have shown that TSP-1 expression supports normal kidney angiostasis, and decreased TSP-1 levels contribute to the angiogenic phenotype of renal cell carcinomas (RCC). The loss of the von Hippel-Lindau tumour suppressor gene (VHL) in these tumours favours stabilization of the Hypoxia Inducible Factors (HIF), which in turn contribute to adapt tumour cells to hostile environments promoting tumour progression. However, HIF-independent regulation of certain genes might also be involved. We have previously shown that TSP-1 is regulated in hypoxia in clear cell RCC (ccRCC) in a HIF-independent manner; however, the effect of VHL protein (pVHL) on TSP-1 expression has not been evaluated. Our results proved that pVHL loss or mutation in its alpha or beta domain significantly decreased TSP-1 levels in ccRCC in a HIF-independent manner. Furthermore, this regulation proved to be important for ccRCC cells behaviour showing that decreased TSP-1 levels rendered ccRCC cells more migratory. This data substantiates a unique regulation pattern for TSP-1 in a pVHL-dependent manner, which may be relevant in the aggressiveness of ccRCC.This work was supported by grants from the Spanish Government (co-funded by European Regional Development Fund, ERDF/FEDER); PI16/02166 and 2017/EEUU/03 to MJC; Red Temática de Excelencia en Investigación en Hipoxia (SAF 2017-90794-REDT) to MJ

High On/Off ratio memristive switching of manganite/cuprate bilayer by interfacial magnetoelectricity

Memristive switching serves as the basis for a new generation of electronic devices. Memristors are two-terminal devices in which the current is turned on and off by redistributing point defects, e.g., vacancies, which is difficult to control. Memristors based on alternative mechanisms have been explored, but achieving both the high On/Off ratio and the low switching energy desirable for use in electronics remains a challenge. Here we report memristive switching in a La_(0.7)Ca_(0.3)MnO_(3)/PrBa_(2)Cu_(3)O_(7) bilayer with an On/Off ratio greater than 103 and demonstrate that the phenomenon originates from a new type of interfacial magnetoelectricity. Using results from firstprinciples calculations, we show that an external electric-field induces subtle displacements of the interfacial Mn ions, which switches on/off an interfacial magnetic “dead” layer, resulting in memristive behavior for spin-polarized electron transport across the bilayer. The interfacial nature of the switching entails low energy cost about of a tenth of atto Joule for write/erase a “bit”. Our results indicate new opportunities for manganite/cuprate systems and other transition-metal-oxide junctions in memristive applications

Erratum: Competition between covalent bonding and charge transfer at complex-oxide interfaces [Physical Review Letters (2014) 112 (196802)]

Corrección de erratas del artículo "Competition between Covalent Bonding and Charge Transfer at Complex-Oxide Interfaces" (Juan Salafranca, Julián Rincón Javier Tornos, Carlos León, Jacobo Santamaria, Elbio Dagotto,Stephen J. Pennycook, Maria Varela)[Phys. Rev. Lett. 112, 196802 (2014)]Depto. de Estructura de la Materia, Física Térmica y ElectrónicaFac. de Ciencias FísicasTRUEpu

Role of small-sized phytoplankton in triggering an ecosystem disruptive algal bloom in a Mediterranean hypersaline coastal lagoon

Preprint2,35

Quasiparticle tunnel electroresistance in superconducting junctions

The term tunnel electroresistance (TER) denotes a fast, non-volatile, reversible resistance switching triggered by voltage pulses in ferroelectric tunnel junctions. It is explained by subtle mechanisms connected to the voltage-induced reversal of the ferroelectric polarization. Here we demonstrate that effects functionally indistinguishable from the TER can be produced in a simpler junction scheme-a direct contact between a metal and an oxide-through a different mechanism: a reversible redox reaction that modifies the oxide's ground-state. This is shown in junctions based on a cuprate superconductor, whose ground-state is sensitive to the oxygen stoichiometry and can be tracked in operando via changes in the conductance spectra. Furthermore, we find that electrochemistry is the governing mechanism even if a ferroelectric is placed between the metal and the oxide. Finally, we extend the concept of electroresistance to the tunnelling of superconducting quasiparticles, for which the switching effects are much stronger than for normal electrons. Besides providing crucial understanding, our results provide a basis for non-volatile Josephson memory devices. The non-volatile switching of tunnel electroresistance in ferroelectric junctions provides the basis for memory and neuromorphic computing devices. Rouco et al. show tunnel electroresistance in superconductor-based junctions that arises from a redox rather than ferroelectric mechanism and is enhanced by superconductivity

Modified magnetic anisotropy at LaCoO_(3)/La_(0.7)Sr_(0.3)MnO_(3) interfaces

Controlling magnetic anisotropy is an important objective towards engineering novel magnetic device concepts in oxide electronics. In thin film manganites, magnetic anisotropy is weak and it is primarily determined by the substrate, through induced structural distortions resulting from epitaxial mismatch strain. On the other hand, in cobaltites, with a stronger spin orbit interaction, magnetic anisotropy is typically much stronger. In this paper, we show that interfacing La0.7Sr0.3MnO3 (LSMO) with an ultrathin LaCoO3 (LCO) layer drastically modifies the magnetic anisotropy of the manganite, making it independent of the substrate and closer to the magnetic isotropy characterizing its rhombohedral structure. Ferromagnetic resonance measurements evidence a tendency of manganite magnetic moments to point out-of-plane suggesting non collinear magnetic interactions at the interface. These results may be of interest for the design of oxide interfaces with tailored magnetic structures for new oxide devices

Identification of a large, fast-expanding HIV-1 subtype B transmission cluster among MSM in Valencia, Spain

We describe and characterize an exceptionally large HIV-1 subtype B transmission cluster occurring in the Comunidad Valenciana (CV, Spain). A total of 1806 HIV-1 protease-reverse transcriptase (PR/RT) sequences from different patients were obtained in the CV between 2004 and 2014. After subtyping and generating a phylogenetic tree with additional HIV-1 subtype B sequences, a very large transmission cluster which included almost exclusively sequences from the CV was detected (n = 143 patients). This cluster was then validated and characterized with further maximum-likelihood phylogenetic analyses and Bayesian coalescent reconstructions. With these analyses, the CV cluster was delimited to 113 patients, predominately men who have sex with men (MSM). Although it was significantly located in the city of Valencia (n = 105), phylogenetic analyses suggested this cluster derives from a larger HIV lineage affecting other Spanish localities (n = 194). Coalescent analyses estimated its expansion in Valencia to have started between 1998 and 2004. From 2004 to 2009, members of this cluster represented only 1.46% of the HIV-1 subtype B samples studied in Valencia (n = 5/143), whereas from 2010 onwards its prevalence raised to 12.64% (n = 100/791). In conclusion, we have detected a very large transmission cluster in the CV where it has experienced a very fast growth in the recent years in the city of Valencia, thus contributing significantly to the HIV epidemic in this locality. Its transmission efficiency evidences shortcomings in HIV control measures in Spain and particularly in Valencia

Do specific antimicrobial stewardship interventions have an impact on carbapenem resistance in Gram-negative bacilli? A multicentre quasi-experimental ecological study: time-trend analysis and characterization of carbapenemases

CarbaPIRASOA team.[Background] Carbapenem-resistant Gram-negative bacilli (CR-GNB) are among the most threatening microorganisms worldwide and carbapenem use facilitates their spread. Antimicrobial stewardship programmes (ASPs) can help to optimize the use of antibiotics. This study evaluates the impact of a multifaceted educational ASP on carbapenem use and on the epidemiology of CR-GNB.[Methods] We conducted a quasi-experimental, time-series study in seven hospitals, from January 2014 to September 2018. The key intervention was composed of educational interviews promoting the appropriate use of carbapenems. The primary endpoints were carbapenem consumption and incidence density (ID) of CR-GNB. All non-duplicated CR-GNB clinical isolates were tested using phenotypic assays and PCR for the presence of carbapenemases. Joinpoint regression and interrupted time-series analyses were used to determine trends.[Results] A decrease in carbapenem consumption throughout the study period [average quarterly percentage change (AQPC) −1.5%, P < 0.001] and a −8.170 (−16.064 to −0.277) level change following the intervention were observed. The ID of CR-Acinetobacter baumannii decreased (AQPC −3.5%, P = 0.02) and the overall ID of CR-GNB remained stable (AQPC −0.4%, P = 0.52). CR-GNB, CR-Pseudomonas aeruginosa and CR-A. baumannii IDs per hospital correlated with the local consumption of carbapenems. The most prevalent carbapenem resistance mechanisms were OXA-23 for CR-A. baumannii (76.1%), OXA-48 for CR-Klebsiella pneumoniae (66%) and no carbapenemases for CR-P. aeruginosa (91.7%). The epidemiology of carbapenemases was heterogeneous throughout the study, especially for carbapenemase-producing Enterobacteriaceae.[Conclusions] In conclusion, a multifaceted, educational interview-based ASP targeting carbapenem prescribing reduced carbapenem use and the ID of CR-A. baumannii.This work was funded by the Spanish Infectious Diseases and Clinical Microbiology Society (SEIMC).Peer reviewe

Human milk and mucosal lacto- and galacto-N-biose synthesis by transgalactosylation and their prebiotic potential in Lactobacillus species

Lacto-N-biose (LNB) and galacto-N-biose (GNB) are major building blocks of free oligosaccharides and glycan moieties of glyco-complexes present in human milk and gastrointestinal mucosa. We have previously characterized the phospho-β-galactosidase GnbG from Lactobacillus casei BL23 that is involved in the metabolism of LNB and GNB. GnbG has been used here in transglycosylation reactions, and it showed the production of LNB and GNB with N-acetylglucosamine and N-acetylgalactosamine as acceptors, respectively. The reaction kinetics demonstrated that GnbG can convert 69 ± 4 and 71 ± 1 % of o-nitrophenyl-β-D-galactopyranoside into LNB and GNB, respectively. Those reactions were performed in a semi-preparative scale, and the synthesized disaccharides were purified. The maximum yield obtained for LNB was 10.7 ± 0.2 g/l and for GNB was 10.8 ± 0.3 g/l. NMR spectroscopy confirmed the molecular structures of both carbohydrates and the absence of reaction byproducts, which also supports that GnbG is specific for β1,3-glycosidic linkages. The purified sugars were subsequently tested for their potential prebiotic properties using Lactobacillus species. The results showed that LNB and GNB were fermented by the tested strains of L. casei, Lactobacillus rhamnosus (except L. rhamnosus strain ATCC 53103), Lactobacillus zeae, Lactobacillus gasseri, and Lactobacillus johnsonii. DNA hybridization experiments suggested that the metabolism of those disaccharides in 9 out of 10 L. casei strains, all L. rhamnosus strains and all L. zeae strains tested relies upon a phospho-β-galactosidase homologous to GnbG. The results presented here support the putative role of human milk oligosaccharides for selective enrichment of beneficial intestinal microbiota in breast-fed infants