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Type 3 secretion system of Pseudomonas aeruginosa
No full textPseudomonas aeruginosa is an opportunistic pathogen, mainly affecting severe patients, such as those in intensive care units (ICUs). High levels of antibiotic resistance and a long battery of virulence factors characterise this pathogen. Among virulence factors, the T3SS (Type 3 Secretion Systems) are especially relevant, being one of the most important virulence factors in P. aeruginosa. T3SS are a complex “molecular syringe” able to inject different effectors in host cells, subverting cell machinery influencing immune responses, and increasing bacterial survival rates. While T3SS have been largely studied and the molecular structure and main effector functions have been established, a series of questions and further points remain to be clarified or established. The key role of T3SS in P. aeruginosa virulence has resulted in the search for T3SS-targeting molecules able to impair their functions and subsequently improve patient outcomes. This review aims to summarise the most relevant features of the P. aeruginosa T3SS. © 2021 Elsevier GmbHConsejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Study of the surface properties and particle-particle interactions in oleic acid-coated Fe3O4 nanoparticles
No full textMagnetite (Fe3O4) nanoparticles coated with organic material are of considerable importance in various areas of engineering, as well as in biomedicine. Several papers show drastic changes in the magnetic properties related to the surface effects and the particle-particle interactions strength. However, there is no consensus about the origin or mechanisms that produce these changes, which could be different depending on the particle size and shape, coating efficiency and particle-particle interaction strength. Aiming to shed light on these issues, oleic acid (OA) coated Fe3O4 nanoparticles with different sizes were synthesized by a thermal decomposition method. Structural and microscopic results revealed Fe3O4 nanoparticles with good crystallinity and almost-spherical or polyhedral shapes depending on the solvent used for the synthesis. Infrared (FTIR) spectroscopy indicated OA molecules attached to the surface of Fe3O4 NPs via bidentate (chelating and/or bridging) bonds; meanwhile, thermogravimetric analysis confirmed the presence of weakly and strongly bonded OA molecules, suggesting a successful coating of Fe3O4 NPs. Magnetization (M) vs. magnetic field (H) curves are consistent with a core/shell structure formed by magnetite/defective magnetite (maghemite) phases, in consistency with FTIR spectroscopy. It was determined lower saturation magnetization values than that expected for bulk magnetite, which was assigned to the likely presence of a fraction of iron ions in low-spin (LS) states in the defective magnetite (maghemite) layer at the particles surface. The magnetic results evidence that depending on the amount of OA coating, it is possible to tune the particle-particle separation distance, avoid particles agglomeration and particle-particle interactions. The temperature dependence of magnetization reveals the presence of non-interacting and interacting NPs. Meanwhile, AC magnetic susceptibility measurements are consistent with those results and provide features related to superparamagnetic (SPM) behavior, assigned to the non-interacting NPs, and interacting SPM behavior, assigned to the interacting NPs, whose interaction strength is not enough to lead to a spin-glass like behavior. © 2021 Elsevier B.V.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Mazzaella canaliculata comb. nov. based on Chondrus canaliculatus (Gigartinaceae, Rhodophyta) from Peru and Chile
No full textChondrus canaliculatus is a red seaweed endemic to Peru and Chile. The name currently represents the only species classified in Chondrus from the southern hemisphere. Based on previous phylogenetic analyses, C. canaliculatus is polyphyletic with respect to Chondrus and possesses unique morpho-anatomical features that distinguish it from other genera in the Gigartinaceae. In this study, expanded phylogenetic analyses using rbcL and COI sequences, a combined data set, and morphological details were further examined to address the taxonomy and evolutionary systematics of C. canaliculatus. Genetic analyses placed C. canaliculatus well within the genus Mazzaella and therefore Mazzaella canaliculata comb. nov. is proposed. Mazzaella canaliculata is distinguished from the other Mazzaella from the southern hemisphere by its dichotomous branching, secondary filaments that persist and leave a well-defined involucre, the absence of terminal tubular cells, and tetrasporangia that are borne from secondary filaments from inner cortical and outer medullary cells. The distributional range of M. canaliculata is extended from the central coast of Peru, Bahía de Pucusana, Lima (12° S) to Chiloé, Chile (41° S). This study contributes to the systematics of the Gigartinaceae and formally validates a problematic species based on a combined analysis of molecular, morphological and anatomical data using recently field collected specimens. Copyright © 2021 Magnolia PressConsejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Taxonomy of Centropomus Lacépède, 1802 (Perciformes: Centropomidae), with focus on the Atlantic species of the genus
No full textCentropomus Lacépède, 1802 comprises 13 species of the fishes popularly knows as snooks, distributed in both Atlantic and Pacific coasts of America. Despite several studies on the group, conflicting taxonomic classifications still exist, including overlapping diagnostic characters, rendering species diagnoses extremely difficult. Herein, we review the taxonomy of Centropomus to elucidate species identities, redefine their diagnoses and to assess interspecific relationships based on the examination of 376 specimens. The study included complementary approaches, as analyses of external morphologic characters, linear and geometric morphometrics, and molecular analyses. Forty-nine characters were used for external morphology, 17 discrete plus 32 linear measurements. Shape and size were analyzed through geometric morphometrics of 185 specimens in lateral view. Partial sequences of the gene cytochrome c oxidase I were obtained for 129 specimens representing 11 species. Based on the consistent results retrieved from the morphologic and molecular analyses, we recognized six species of Centropomus from the Atlantic coast (C. ensiferus, C. irae, C. parallelus, C. pectinatus, C. poeyi and C. undecimalis). Centropomus mexicanus is treated as a junior synonym of C. parallelus. Six species from the Pacific coast are also tentatively recognized (C. armatus, C. medius, C. nigrescens, C. robalito, C. unionensis, and C. viridis), however further studies on the Pacific species are still needed. Information on type material, diagnosis, distribution, and taxonomic comments are provided for each species. An identification key to the species of Centropomus is presented. Copyright © 2021 Magnolia PressConsejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Generalized fractal dimensions of invariant measures of full-shift systems over compact and perfect spaces: Generic behavior
No full textIn this paper, we show that, for topological dynamical systems with a dense set (in the weak topology) of periodic measures, a typical (in Baire's sense) invariant measure has, for each q>0, zero lower q-generalized fractal dimension. This implies, in particular, that a typical invariant measure has zero upper Hausdorff dimension and zero lower rate of recurrence. Of special interest is the full-shift system (X,T) (where X=Mℤ is endowed with a sub-exponential metric and the alphabet M is a compact and perfect metric space), for which we show that a typical invariant measure has, for each q>1, infinite upper q-correlation dimension. Under the same conditions, we show that a typical invariant measure has, for each s∈(0,1) and each q>1, zero lower s-generalized and infinite upper q-generalized dimensions. © 2021 Walter de Gruyter GmbH, Berlin/Boston 2021.Fondo Nacional de Desarrollo Científico y Tecnológico - Fondecy
Metabolomic approach of the antiprotozoal activity of medicinal Piper species used in Peruvian Amazon
No full textEthnopharmacological relevance: In the Peruvian Amazon as in the tropical countries of South America, the use of medicinal Piper species (cordoncillos) is common practice, particularly against symptoms of infection by protozoal parasites. However, there is few documented information about the practical aspects of their use and few scientific validation. The starting point of this work was a set of interviews of people living in six rural communities from the Peruvian Amazon (Alto Amazonas Province) about their uses of plants from Piper genus: one community of Amerindian native people (Shawi community) and five communities of mestizos. Infections caused by parasitic protozoa take a huge toll on public health in the Amazonian communities, who partly fight it using traditional remedies. Validation of these traditional practices contributes to public health care efficiency and may help to identify new antiprotozoal compounds. Aims of study: To record and validate the use of medicinal Piper species by rural people of Alto Amazonas Province (Peru) and annotate active compounds using a correlation study and a data mining approach. Materials and methods: Rural communities were interviewed about traditional medication against parasite infections with medicinal Piper species. Ethnopharmacological surveys were undertaken in five mestizo villages, namely: Nueva Arica, Shucushuyacu, Parinari, Lagunas and Esperanza, and one Shawi community (Balsapuerto village). All communities belong to the Alto Amazonas Province (Loreto region, Peru). Seventeen Piper species were collected according to their traditional use for the treatment of parasitic diseases, 35 extracts (leaves or leaves and stems) were tested in vitro on P. falciparum (3D7 chloroquine-sensitive strain and W2 chloroquine-resistant strain), Leishmania donovani LV9 strain and Trypanosoma brucei gambiense. Assessments were performed on HUVEC cells and RAW 264.7 macrophages. The annotation of active compounds was realized by metabolomic analysis and molecular networking approach. Results: Nine extracts were active (IC50 ≤ 10 μg/mL) on 3D7 P. falciparum and only one on W2 P. falciparum, six on L. donovani (axenic and intramacrophagic amastigotes) and seven on Trypanosoma brucei gambiense. Only one extract was active on all three parasites (P. lineatum). After metabolomic analyses and annotation of compounds active on Leishmania, P. strigosum and P. pseudoarboreum were considered as potential sources of leishmanicidal compounds. Conclusions: This ethnopharmacological study and the associated in vitro bioassays corroborated the relevance of use of Piper species in the Amazonian traditional medicine, especially in Peru. A series of Piper species with few previously available phytochemical data have good antiprotozoal activity and could be a starting point for subsequent promising work. Metabolomic approach appears to be a smart, quick but still limited methodology to identify compounds with high probability of biological activity. © 2020 Elsevier B.V.Fondo Nacional de Desarrollo Científico y Tecnológico - Fondecy
Finite-Expansivity and N-Shadowing
No full textWe prove that every finite-expansive homeomorphism with the shadowing property has a kind of stability. This stability will be good enough to imply both the shadowing property and the denseness of periodic points in the chain recurrent set. Next we analyze the N-shadowing property which is really stronger than the multishadowing property in Cherkashin and Kryzhevich (Topol Methods Nonlinear Anal 50(1): 125–150, 2017). We show that an equicontinuous homeomorphism has the N-shadowing property for some positive integer N if and only if it has the shadowing property. © 2021, Sociedade Brasileira de Matemática.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Enhanced antibiotic resistance as a collateral COVID-19 pandemic effect?
No full textIt explains the usefulness of antimicrobials, the actions they carry out to apply them against the spread of COVID-19 and claim the delay generated by the lack of adequate knowledge of the usefulness of antibiotics in the population.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
dPyx: herramienta de apoyo a la evaluación de repositorios
No full textPresenta dPyx, plataforma de software libre que facilitará la autoevaluación de los repositorios bajo estándares y lineamientos de la Guía ALICIA, con el fin de recabar la información de cada institución y su comparación de crecimiento a lo largo del tiempo
Mitos y realidades de la praxis cualitativa: libro de ponencias
No full textReúne las ponencias presentadas por investigadores Latinoamericanos sobre los Mitos y realidades de la praxis cualitativa, las mismas que fueron expuestas en el Seminario Virtual del mismo nombre, evento que fuera organizado por Recursos para la Investigación en diciembre del año 2020