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1.
Phys Rev Lett ; 130(10): 105101, 2023 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-36962036

RESUMEN

A quasilinear plasma transport theory that incorporates Fokker-Planck dynamical friction (drag) and pitch angle scattering is self-consistently derived from first principles for an isolated, marginally unstable mode resonating with an energetic minority species. It is found that drag fundamentally changes the structure of the wave-particle resonance, breaking its symmetry and leading to the shifting and splitting of resonance lines. In contrast, scattering broadens the resonance in a symmetric fashion. Comparison with fully nonlinear simulations shows that the proposed quasilinear system preserves the exact instability saturation amplitude and the corresponding particle redistribution of the fully nonlinear theory. Even in situations in which drag leads to a relatively small resonance shift, it still underpins major changes in the redistribution of resonant particles. This novel influence of drag is equally important in plasmas and gravitational systems. In fusion plasmas, the effects are especially pronounced for fast-ion-driven instabilities in tokamaks with low aspect ratio or negative triangularity, as evidenced by past observations. The same theory directly maps to the resonant dynamics of the rotating galactic bar and massive bodies in its orbit, providing new techniques for analyzing galactic dynamics.

2.
Opt Lett ; 47(10): 2498-2501, 2022 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-35561384

RESUMEN

Integrated silicon nitride waveguides of 100 nm height can achieve ultralow propagation losses below 0.1 dB/cm at the 1550 nm wavelength band but lack the scattering strength to form efficient grating couplers. An enhanced grating coupler design based on an amorphous silicon layer on top of silicon nitride is proposed and demonstrated to improve the directionality of the coupler. The fabrication process is optimized for a self-alignment process between the amorphous silicon and silicon nitride layers without increasing waveguide losses. Experimental coupling losses of 5 dB and a 3 dB bandwidth of 75 nm are achieved with both regular and focusing designs.

3.
Oecologia ; 198(3): 645-661, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-35279723

RESUMEN

Epiphyte communities comprise important components of many forest ecosystems in terms of biomass and diversity, but little is known regarding trade-offs that underlie diversity and structure in these communities or the impact that microclimate has on epiphyte trait allocation. We measured 22 functional traits in vascular epiphyte communities across six sites that span a microclimatic gradient in a tropical montane cloud forest region in Costa Rica. We quantified traits that relate to carbon and nitrogen allocation, gas exchange, water storage, and drought tolerance. Functional diversity was high in all but the lowest elevation site where drought likely limits the success of certain species with particular trait combinations. For most traits, variation was explained by relationships with other traits, rather than differences in microclimate across sites. Although there were significant differences in microclimate, epiphyte abundance, and diversity, we found substantial overlap in multivariate trait space across five of the sites. We found significant correlations between functional traits, many of which related to water storage (leaf water content, leaf thickness, hydrenchymal thickness), drought tolerance (turgor loss point), and carbon allocation (specific leaf area, leaf dry matter content). This suite of trait correlations suggests that the epiphyte community has evolved functional strategies along with a drought avoidance versus drought tolerance continuum where leaf succulence emerged as a pivotal overall trait.


Asunto(s)
Sequías , Clima Tropical , Ecosistema , Bosques , Hojas de la Planta
4.
Mol Phylogenet Evol ; 163: 107261, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34273504

RESUMEN

Located at the junction between Europe, Africa, and Asia, with distinct evolutionary origins and varied ecological and geographical settings, together with a marked history of changes in orogeny and configuration of the main river basins, turned the Eastern Mediterranean into a region of high diversity and endemism of freshwater taxa. Freshwater mussels (Bivalvia, Unionidae) from the Western Palearctic have been widely studied in their European range, but little attention has been dedicated to these taxa in the Eastern Mediterranean region and their diversity and phylogeography are still poorly understood. The present study aims to resolve the diversity, biogeography, and evolutionary relationships of the Eastern Mediterranean freshwater mussels. To that end, we performed multiple field surveys, phylogenetic analyses, and a thorough taxonomic revaluation. We reassessed the systematics of all Unionidae species in the region, including newly collected specimens across Turkey, Israel, and Iran, combining COI + 16S + 28S and COI phylogenies with molecular species delineation methods. Phylogeographical patterns were characterized based on published molecular data, newly sequenced specimens, and species distribution data, as well as ancestral range estimations. We reveal that Unionidae species richness in the Eastern Mediterranean is over 70% higher than previously assumed, counting 19 species within two subfamilies, the Unioninae (14) and Gonideinae (5). We propose two new species, Anodonta seddonisp. nov. and Leguminaia anatolicasp. nov. Six additional taxa, Unio delicatusstat. rev., Unio eucirrusstat. rev., Unio huetistat. rev., Unio sesirmensisstat. rev., Unio terminalisstat. rev. removed from the synonymy of Unio tigridis, as well as Unio damascensisstat. rev. removed from the synonymy of Unio crassus, are re-described. The nominal taxa Unio rothi var. komarowi O. Boettger, 1880 and Unio armeniacus Kobelt, 1911 are proposed as new synonyms of Unio bruguierianus, and Anodonta cyrea Drouët, 1881 and Anodonta cilicica Kobelt & Rolle, 1895 as new synonyms of Anodonta anatina. Also, the presence of Unio tumidus in the Maritza River is confirmed. The phylogeographic patterns described here are interpreted concerning major past geological events. Conservation needs and implications are presented, together with populations and species conservation priorities.


Asunto(s)
Bivalvos , Unio , Unionidae , Animales , Agua Dulce , Filogenia , Unionidae/genética
5.
Conserv Biol ; 35(5): 1367-1379, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34355419

RESUMEN

Theidentification of key biodiversity areas (KBA) was initiated by the International Union for Conservation of Nature in 2004 to overcome taxonomic biases in the selection of important areas for conservation, including freshwater ecosystems. Since then, several KBAs have been identified mainly based on the presence of trigger species (i.e., species that trigger either the vulnerability and or the irreplaceability criterion and thus identify a site as a KBA). However, to our knowledge, many of these KBAs have not been validated. Therefore, classical surveys of the taxa used to identify freshwater KBAs (fishes, molluscs, odonates, and aquatic plants) were conducted in Douro (Iberian Peninsula) and Sebou (Morocco) River basins in the Mediterranean Biodiversity Hotspot. Environmental DNA analyses were undertaken in the Moroccan KBAs. There was a mismatch between the supposed and actual presence of trigger species. None of the trigger species were found in 43% and 50% of all KBAs surveyed in the Douro and Sebou basins, respectively. Shortcomings of freshwater KBA identification relate to flawed or lack of distribution data for trigger species. This situation results from a misleading initial identification of KBAs based on poor (or even inaccurate) ecological information or due to increased human disturbance between initial KBA identification and the present. To improve identification of future freshwater KBAs, we suggest selecting trigger species with a more conservative approach; use of local expert knowledge and digital data (to assess habitat quality, species distribution, and potential threats); consideration of the subcatchment when delineating KBAs boundaries; thoughtful consideration of terrestrial special areas for conservation limits; and periodic field validation.


Alarming decline of freshwater trigger species in western Mediterranean Key Biodiversity Areas Resumen La identificación de las áreas clave de biodiversidad (ACB) fue iniciada por la Unión Internacional para la Conservación de la Naturaleza en 2004 con el objetivo de sobreponerse a los sesgos taxonómicos en la selección de áreas importantes para la conservación, incluyendo los ecosistemas de agua dulce. Desde entonces, varias ACB han sido identificadas principalmente con base en la presencia de especies desencadenantes (es decir, especies que desencadenan el criterio de vulnerabilidad o de carácter irremplazable y por lo tanto identifican a un sitio como una ACB). Sin embargo, a nuestro conocimiento, muchas de estas ACB no han sido validadas. Por lo tanto, los censos clásicos de taxones utilizados para identificar las ACB de agua dulce (peces, moluscos, odonatos y plantas acuáticas) fueron realizados en las cuencas de los ríos Duero (Península Ibérica) y Sebou (Marruecos) en el Punto Caliente de Biodiversidad del Mediterráneo. Realizamos análisis de ADN ambiental en las ACB de Marruecos. Hubo una discrepancia entre la supuesta presencia y la actual presencia de especies desencadenantes. Ninguna de las especies desencadenantes se encontró en 43% y 50% de las ACB censadas en las cuencas del Duero y del Sebou, respectivamente. Las deficiencias en la identificación de las ACB de agua dulce están relacionadas con la carencia de datos o datos erróneos sobre la distribución de las especies desencadenantes. Esta situación resulta en una identificación inicial engañosa de las ACB con base en información ecológica deficiente (o incluso incorrecta) o también puede deberse al incremento en las perturbaciones humanas ocurridas entre la identificación de la ACB y el presente. Para mejorar la identificación de ACB de agua dulce en el futuro, sugerimos que la selección de especies desencadenantes se realice con un enfoque más conservador; que se usen el conocimiento local de los expertos y los datos digitales (para evaluar la calidad del hábitat, la distribución de las especies y las amenazas potenciales); que se consideren las subcuencas cuando se delimiten las fronteras de las ACB; que se consideren cuidadosamente las áreas de especies terrestres para los límites de conservación; y que se realicen validaciones periódicas de campo.


Asunto(s)
Conservación de los Recursos Naturales , Ecosistema , Animales , Biodiversidad , Peces , Agua Dulce , Humanos
6.
J Appl Microbiol ; 131(4): 1942-1957, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-33709536

RESUMEN

AIMS: In-vitro/In-vivo evaluation of cholesterol-lowering probiotic strain Lactobacillus paracasei DTA81 and the possible connection with the gut microbiota modulation. METHODS AND RESULTS: In the present study, strain DTA81 has been evaluated for the possible influence on blood lipid and glucose concentrations, modulation of the immune system, gastrointestinal survivability and modulation of gut microbiota in BALB/c mice receiving a high-fat diet. After 6 weeks of treatment, a significant reduction of total cholesterol and fasting blood sugar (FBS) among animals treated with L. paracasei DTA81 has been recorded. Comparison of colon tissue levels of different cytokines revealed a significant reduction of the inflammatory cytokine interleukin-6. The comparison of gut microbiota using the 16S rRNA approach indicated that the treatment with L. paracasei DTA81 significantly increased the taxa Bacteroidetes and Coprococcus. Moreover, the genome of DTA81 was sequenced for the in-silico assessment, and the analysis indicated the presence of cholesterol assimilation-related genes as well as the absence of negative traits such as transmissible antibiotic resistance genes, plasmids and prophage regions. CONCLUSION: The outcome of this study revealed the in-vitro and in-vivo properties of L. paracasei DTA81 and the possible mechanism between consumption of this strain, the abundance of Bacteriodetes/Coprococcus taxa, immunomodulatory activity and the subsequent reduction of cholesterol/FBS in BALB/c mice. SIGNIFICANCE AND IMPACT OF THE STUDY: Lactobacillus paracasei DTA81 as a non-pharmacological potential probiotic supplement can influence metabolic homeostasis in individuals, particularly those adopting high-fat diets, and it can contribute to reduce coronary heart disease.


Asunto(s)
Microbioma Gastrointestinal , Lacticaseibacillus paracasei , Probióticos , Animales , Colesterol , Dieta Alta en Grasa , Ratones , Ratones Endogámicos BALB C , ARN Ribosómico 16S/genética
7.
Mol Phylogenet Evol ; 146: 106755, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32028028

RESUMEN

Freshwater mussels (Bivalvia: Unionidae) is a diverse family with around 700 species being widespread in the Northern Hemisphere and Africa. These animals fulfill key ecological functions and provide important services to humans. Unfortunately, populations have declined dramatically over the last century, rendering Unionidae one of the world's most imperiled taxonomic groups. In Far East Asia (comprising Japan, Korea, and Eastern Russia), conservation actions have been hindered by a lack of basic information on the number, identity, distribution and phylogenetic relationships of species. Available knowledge is restricted to studies on national and sub-national levels. The present study aims to resolve the diversity, biogeography and evolutionary relationships of the Far East Asian Unionidae in a globally comprehensive phylogenetic and systematic context. We reassessed the systematics of all Unionidae species in the region, including newly collected specimens from across Japan, South Korea, and Russia, based on molecular (including molecular species delineation and a COI + 28S phylogeny) and comparative morphological analyses. Biogeographical patterns were then assessed based on available species distribution data from the authors and previous reference works. We revealed that Unionidae species richness in Far East Asia is 30% higher than previously assumed, counting 43 species (41 native + 2 alien) within two Unionidae subfamilies, the Unioninae (32 + 1) and Gonideinae (9 + 1). Four of these species are new to science, i.e. Beringiana gosannensissp. nov., Beringiana fukuharaisp. nov., Buldowskia kamiyaisp. nov., and Koreosolenaia sitgyensisgen. & sp. nov. We also propose a replacement name for Nodularia sinulata, i.e. Nodularia breviconchanom. nov. and describe a new tribe (Middendorffinaiini tribe nov.) within the Unioninae subfamily. Biogeographical patterns indicate that this fauna is related to that from China south to Vietnam until the Mekong River basin. The Japanese islands of Honshu, Shikoku, Kyushu, Hokkaido, and the Korean Peninsula were identified as areas of particularly high conservation value, owing to high rates of endemism, diversity and habitat loss. The genetically unique species within the genera Amuranodonta, Obovalis, Koreosolenaiagen. nov., and Middendorffinaia are of high conservation concern.


Asunto(s)
Unionidae/clasificación , Animales , Evolución Biológica , Agua Dulce , Japón , Corea (Geográfico) , Filogenia , Filogeografía , Federación de Rusia , Unionidae/genética
8.
Med Oral Patol Oral Cir Bucal ; 24(5): e588-e594, 2019 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-31433390

RESUMEN

BACKGROUND: Determine the behavior of the maxillofacial trauma of adults treated in 3 tertiary care centers in the central zone of Chile. MATERIAL AND METHODS: descriptive, cross-sectional, multicenter study, based on the prospective records of maxillofacial trauma cases attended between May 2016 and April 2017 by dental and maxillofacial clinical teams of Adult Emergency Units of hospitals Dr. Sótero del Río (metropolitan region), Carlos Van Buren and Dr. Gustavo Fricke (region V). Age, sex, date of occurrence, type of trauma according to ICD-10, etiology, legal medical prognosis and associated injuries were recorded, stratifying by sex and age. Chi square and unpaired Wilcoxon tests were used to compare by groups. RESULTS: 2.485 cases and 3.285 injuries were investigated. The male: female ratio was 1.7: 1 with age under 30 predominant, followed by older adults. Variability was observed in the yearly, weekly and daily presentation. The highest frequencies were in January and September, weekends and at night. The main etiologies were violence (42.3%), falls (13.1%) and road traffic crashes (12.9%) with differences by age and sex (p <0.05). 31,9% of the injuries occurred in hard tissue, being fractures in nasal bones predominant (S02.2). CONCLUSIONS: the profile of the maxillofacial trauma in Chile seems to be mixed by age, affecting young people and the elderly. The male sex predominates; the main cause, which varies by age group, is violence. Their surveillance is possible from hospital emergency records.


Asunto(s)
Accidentes de Tránsito , Traumatismos Maxilofaciales , Adolescente , Anciano , Chile , Estudios Transversales , Femenino , Humanos , Masculino , Estudios Retrospectivos , Violencia
9.
Mol Phylogenet Evol ; 100: 322-332, 2016 07.
Artículo en Inglés | MEDLINE | ID: mdl-27118180

RESUMEN

The Potomida genus (Bivalvia, Unionida) has a Circum-Mediterranean distribution and like other freshwater mussel species, its populations have suffered dramatic declines. Although this genus is currently considered as monotypic, it has a long history of taxonomic revisions and presently many aspects of its systematics and evolutionary history are unclear. We sampled a total of 323 individuals from 39 different sites across the Potomida genus distribution, and sequenced two mitochondrial (16S rDNA and Cytochrome c Oxidase Subunit I) and one nuclear (28S rDNA) genes to clarify its phylogeny and phylogeographic history. Our results show that the genus includes two well-supported clades, one comprising solely the western Mediterranean species Potomida littoralis, and the other including two eastern Mediterranean species, the Greek endemic P. acarnanica and the Anatolian and Middle Eastern P. semirugata. We suggest that Potomida started radiating during the upper Miocene, and that both vicariance and dispersal events shaped the diversification and distribution of the genus along the Mediterranean region. P. littoralis is further divided in two mitochondrial lineages, one restricted to Europe and the other occurring mostly in North Africa. Moreover, some European basins present both lineages in sympatry. The conservation status of the three recognized species should be reevaluated, particularly P. acarnanica, since it is restricted to two Greek river basins presenting a high risk of extinction. Overall, our results clarify some important gaps in knowledge concerning the phylogeny, phylogeography and evolution of the Potomida genus in the Mediterranean region with important taxonomical, ecological and conservational implications.


Asunto(s)
Bivalvos/genética , Animales , Secuencia de Bases , ADN Mitocondrial/genética , Complejo IV de Transporte de Electrones/genética , Evolución Molecular , Agua Dulce , Especiación Genética , Región Mediterránea , Tipificación de Secuencias Multilocus , Filogenia , Filogeografía , ARN Ribosómico 16S/genética
10.
Sci Total Environ ; 864: 161073, 2023 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-36572307

RESUMEN

Information about biotic interactions (e.g. competition, predation, parasitism, diseases, mutualism, allelopathy) is fundamental to better understand species distribution and abundance, ecosystem functioning, and ultimately guide conservation efforts. However, conservation planning often overlooks these important interactions. Here, we aim to demonstrate a new framework to include biotic interactions into Marxan. For that, we use freshwater mussels and fish interaction (as mussels rely on fishes to complete their life cycle) in the Douro River basin (Iberian Peninsula) as a case study. While doing that, we also test the importance of including biotic interactions into conservation planning exercises, by running spatial prioritisation analysis considering either: 1) only the target species (freshwater mussels); 2) freshwater mussels and their obligatory hosts (freshwater fishes); 3) freshwater mussels, fishes and their interactions. With this framework we found that biotic interactions tend to be underrepresented when the data on both freshwater mussels and fishes is not simultaneously included in the spatial prioritisation. Overall, the priority areas selected across all scenarios are mostly located in the western part of the Douro River basin, where most freshwater mussels and fishes still occur. Given the low overlap of priority areas identified here and the current Natura 2000 network, our approach may be useful for establishing (or enlarging) protected areas, especially in light of the EU Biodiversity Strategy for 2030. Also, this work may provide guidance for future habitat restoration and management of main threats to freshwater biodiversity.


Asunto(s)
Conservación de los Recursos Naturales , Ecosistema , Animales , Biodiversidad , Agua Dulce , Ríos , Peces
11.
Mol Phylogenet Evol ; 64(3): 582-91, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22634241

RESUMEN

The origin of Saharan biodiversity is poorly understood, in part because the geological and paleoclimatic events that presumably shaped species diversity are still controversial, but also because few studies have explored causal explanations for the origin of Saharan diversity using a phylogenetic framework. Here, we use mtDNA (16S and ND4 genes) and nDNA (MC1R and CMOS genes) to infer the relationships and biogeographic history of North African agamas (genus Agama). Agamas are conspicuous, diverse and abundant African lizards that also occur in the Saharan xeric and mesic environments. Our results revealed the presence of three Agama lineages in North Africa: one Afrotropical, one Sahelo-Saharan, and one broadly distributed in North Africa and mainly Saharan. Southern Mauritania contains the highest known diversity, with all three lineages present. Results suggest that agamas colonized the Sahara twice, but only one lineage was able to radiate and diversify there. Species in the Saharan lineage are mostly allopatric, and their splitting, genetic diversity and distribution are greatly explained by mountain ranges. One species in this lineage has colonized the Mediterranean climatic zone (A. impalearis), and another one the Sahel savannah (A. boueti). The other lineage to colonize the Sahara corresponds to A. boulengeri, an eminently Sahelian species that also inhabits Saharan mountain ranges in Mauritania and Mali. Phylogenetic analyses indicate that allopatric montane populations within some currently recognized species are also genetically divergent. Our study therefore concludes that vicariant speciation is a leading motor of species diversification in the area: Inside the Sahara, associated to mountain-ranges isolated by dune seas and bare plains; outside, associated to less harsh climates to the North and South. Paleoclimatic oscillations are suggested as causal explanations of the vicariant distribution and origin of species. Agamas are thought to have colonized northern Africa during wet periods, with subsequent dry periods fragmenting species distribution and leading to allopatric populations associated to milder and wetter climates in the Mediterranean, Sahel, and in Saharan mountains, in an island-model fashion. Finally, our results support the synonymization of A. castroviejoi with A. boueti, the reciprocal monophyly of all other North African agamas, and suggest one candidate species within A. boulengeri.


Asunto(s)
Clima Desértico , Especiación Genética , Lagartos/clasificación , Filogenia , África del Norte , Animales , Biodiversidad , ADN Mitocondrial/genética , Lagartos/genética , Filogeografía , Alineación de Secuencia , Análisis de Secuencia de ADN
12.
Mol Microbiol ; 73(1): 20-31, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19508285

RESUMEN

In Bacillus subtilis, the transcription factor PerR is an iron dependant sensor of H(2)O(2). The sensing mechanism relies on a selective metal catalysed oxidation of two histidine residues of the regulatory site. Here we present the first crystal structure of the active PerR protein in complex with a Mn(2+) ion. In addition, X-ray absorption spectroscopy experiments were performed to characterize the corresponding iron form of the protein. Both studies reveal a penta-coordinate arrangement of the regulatory site that involves three histidines and two aspartates. One of the histidine ligand belongs to the N-terminal domain. Binding of this residue to the regulatory metal allows the protein to adopt a caliper-like conformation suited to DNA binding. Since this histidine is conserved in all PerR and a vast majority of Fur proteins, it is likely that the allosteric switch induced by the regulatory metal is general for this family of metalloregulators.


Asunto(s)
Bacillus subtilis/metabolismo , Proteínas Bacterianas/metabolismo , Peróxido de Hidrógeno/metabolismo , Proteínas Represoras/metabolismo , Bacillus subtilis/genética , Proteínas Bacterianas/genética , Sitios de Unión , Regulación Bacteriana de la Expresión Génica , Magnesio/metabolismo , Modelos Moleculares , Estructura Cuaternaria de Proteína , Proteínas Represoras/genética , Análisis Espectral , Rayos X
13.
Plant Dis ; 93(6): 666, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-30764426

RESUMEN

China tree (Melia azedarach L.), originally from Asia, is an exotic deciduous species in Brazil and is used as an ornamental shade tree in the southern region of the country. Since 2005, plants displaying yellowing, little leaves, witches' broom, and decline have been observed in the State of Rio Grande do Sul. In the streets and avenues of the capital city of Porto Alegre, there are approximately 173 tree species and China tree (6.57% of all trees) is among the top 10 (80,000 China trees and most are symptomatic). Plants with those symptoms are very distinctive and have been found also in the cities of Livramento, Rio Grande, Santa Maria, and Vacaria, places located in seashore areas, and along highways everywhere in the state. The high incidence seems to be related to drought during the last few years. These symptoms are typical of a disease identified by yellowing or decline of China tree associated with phytoplasma and previously reported in the neighboring countries of Argentina, Paraguay, and Bolivia (2). To demonstrate the presence of phytoplasma in diseased trees and to confirm its identity, total DNA was extracted from China tree leaf midribs collected from 10 symptomatic and three asymptomatic plants. Nested PCR was performed with the P1/P7 primer pair in the primary PCR to amplify a 1.8-kb fragment encompassing the 16S rRNA gene, the 16S-23S spacer region, and the 5' end of the 23S rRNA gene, while the secondary PCR was primed by the R16F2n/R16R2 primer pair to amplify a 1.2-kb fragment of the 16S rRNA gene from the 1.8-kb fragment (3,4). DNA fragments of 1.2 kb amplified from nested PCR were analyzed by restriction fragment length polymorphism with restriction enzymes AluI, HhaI, HpaII, KpnI, MboI, MseI, and RsaI, revealing identical profiles for each amplicon and demonstrating that a phytoplasma belonging to group 16SrIII, subgroup B (16SrIII-B) (1) was associated consistently with all symptomatic plants. BLAST analysis revealed 99% identity among these cloned 1.2-kb sequences and representative sequences of phytoplasmas affiliated with group 16SrIII (GenBank Accession Nos. AY081817 and AF147706). A majority consensus sequence representing the phytoplasma found in China trees was selected and deposited in GenBank (Accession No. FJ404775). These results were confirmed by observation with transmission electron microscopy of pleomorphic bodies 400 to 2,000 nm in diameter in the phloem sieve tubes of all symptomatic trees. No phytoplasma was detected or visualized in asymptomatic samples. These results corroborate those from studies conducted in neighboring countries that demonstrated the association between phytoplasmas of group 16SrIII and decline of China trees (1). In conclusion, the current study revealed that a phytoplasma affiliated with group 16SrIII-B is associated with the decline of China tree in Brazil, a disease previously described based solely on symptoms (2). The incidence and severity of the disease are enough to prevent further use of these trees as landscape plants in southern Brazil. References: (1) J. D. Arneodo et al. J. Phytopathol. 155:70, 2007. (2) M. Dalbosco et al. Fitopatol. Bras. 30(Suppl.):177, 2005. (3) S. Deng and C. Hiruki. J. Microbiol. Methods 14:53, 1991. (4) C. D. Smart et al. Appl. Environ. Microbiol. 62:2988, 1996.

14.
Materials (Basel) ; 12(7)2019 Apr 04.
Artículo en Inglés | MEDLINE | ID: mdl-30987382

RESUMEN

Additive manufacturing has revolutionized the manufacturing paradigm in recent years due to the possibility of creating complex shaped three-dimensional parts which can be difficult or impossible to obtain by conventional manufacturing processes. Among the different additive manufacturing techniques, wire and arc additive manufacturing (WAAM) is suitable to produce large metallic parts owing to the high deposition rates achieved, which are significantly larger than powder-bed techniques, for example. The interest in WAAM is steadily increasing, and consequently, significant research efforts are underway. This review paper aims to provide an overview of the most significant achievements in WAAM, highlighting process developments and variants to control the microstructure, mechanical properties, and defect generation in the as-built parts; the most relevant engineering materials used; the main deposition strategies adopted to minimize residual stresses and the effect of post-processing heat treatments to improve the mechanical properties of the parts. An important aspect that still hinders this technology is certification and nondestructive testing of the parts, and this is discussed. Finally, a general perspective of future advancements is presented.

15.
Braz J Biol ; 78(3): 509-516, 2018 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-29995113

RESUMEN

Typha domingensis (cattail) is a native macrophyte known by its capacity to tolerate several heavy metals effects and the potential use for phytoremediation. However, in despite that cadmium (Cd) is one of the most toxic pollutants; its effects in T. domingensis biology remain uninvestigated. Thus, the objective of this study was to study the tolerance of T. domingensis to cadmium contamination by evaluating its growth, Cd uptake, leaf anatomy and gas exchange. The experiment was designed using three cadmium concentrations (0, 10 and 50 µM) and ten replicates for 90 days. The cadmium uptake, growth, gas exchange, chlorophyll content and leaf anatomy were evaluated. Data was submitted to ANOVA and Scott-Knott test for P<0.05. Typha domingensis accumulates Cd proportionally to its concentration on the solution and the content of this metal was higher in roots as compared to shoots. Plants showed no significant modifications on growth parameters such as the biomass production, number of leaves, number of clones and the biomass allocation to organs. The photosynthesis, transpiration and chlorophyll content were not modified by Cd. Most anatomical traits evaluated were not modified by the metal but the stomatal density and the proportion of vascular tissues were reduced under 50 µM of Cd. In despite, the leaf anatomy showed no toxicity evidences for any Cd level. The absence of growth reduction and the stability of anatomical and physiological traits give insight about the Cd tolerance of this species. Therefore, T. domingensis is able to overcome Cd toxicity and shows potential for phytoremediation.


Asunto(s)
Cadmio/metabolismo , Hojas de la Planta/metabolismo , Typhaceae/crecimiento & desarrollo , Typhaceae/metabolismo , Biodegradación Ambiental , Biomasa , Cadmio/toxicidad , Clorofila/química , Clorofila/metabolismo , Relación Dosis-Respuesta a Droga , Fotosíntesis/fisiología , Hojas de la Planta/química , Raíces de Plantas/química , Raíces de Plantas/metabolismo
16.
Genome Announc ; 6(4)2018 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-29371355

RESUMEN

The genome sequence of Rhizobium sullae strain HCNT1, isolated from root nodules of the legume Hedysarum coronarium growing in wild stands in Tuscany, Italy, is described here. Unlike other R. sullae strains, this isolate features a truncated denitrification pathway lacking NO/N2O reductase activity and displaying high sensitivity to nitrite under anaerobic conditions.

17.
Dalton Trans ; 47(9): 3119-3127, 2018 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-29313540

RESUMEN

In this work, a carbon replica derived from a vinylbenzenesulfonate-intercalated layered double hydroxide (CR-LDH) was applied to remove the Dicamba organochlorine herbicide from aqueous solution. The samples were characterized by several experimental techniques such as X-ray diffraction (XRD), thermogravimetric analysis coupled with differential scanning calorimetry and mass spectrometry (TGA-DSC-MS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Raman spectroscopy, N2 adsorption/desorption and zeta potential analysis. The CR-LDH sample presents a very high specific surface area (2345 m2 g-1). The adsorption experiment typically followed the Langmuir isotherm model and the adsorption kinetics was best fitted with a pseudo second-order model. The maximum adsorption capacity of Dicamba herbicide onto CR-LDH was 279 mg g-1. CR-LDH presented a higher adsorption capacity than other carbon adsorbent materials reported in the literature.

18.
Transplant Proc ; 39(7): 2095-8, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17889104

RESUMEN

INTRODUCTION: Epidemiological studies have shown that demographic, clinical, and histological donor characteristics influence renal function after transplantation, but whether these variables are independent predictors has not been established. The aim of this study was to evaluate the relative contribution of different donor variables on glomerular filtration rates (GFRs) at 3 months. PATIENTS AND METHODS: We analyzed single renal transplants performed at our center from January 2000 to July 2004. Donor variables included age, gender, weight and height, cause of death, duration of brain death, serum creatinine at admission and preprocurement, history of arterial hypertension or diabetes mellitus, and smoking habit. Donor chronic damage score was calculated in preimplantation biopsies as was the addition of interstitial fibrosis, fibrous intimal thickening, and glomerulosclerosis (<10% = 0, >10% = 1). Donor and recipient GFRs were calculated according to the Cockroft-Gault formula. RESULTS: We analyzed 202 transplants obtained from 113 deceased donors. A renal biopsy was available in 111 transplants. Recipient GFR at 3 months correlated negatively with donor age (R = -0.32, P < .01) and donor chronic damage score (R = 0.32, P < .01). GFR was lower among recipients of female versus male donors (50 +/- 15 vs 60 +/- 20 mL/min; P < .01). Donor cerebrovascular accident death (53 +/- 19 vs 63 +/- 19 mL/min; P < .01) and hypertension (48 +/- 16 vs 59 +/- 20 mL/min; P < .01) were also associated with lower GFR at 3 months. There was a positive correlation between GFR at admission, GFR preprocurement, and GFR at 3 months (R = 0.32 and R = 0.18 respectively; P < .01). Stepwise regression analysis included chronic damage score, GFR at admission, and donor gender but not donor age as independent predictors of GFR at 3 months (R = 0.50; P < .01). CONCLUSION: Donor structural and functional parameters are independent predictors of renal function at 3 months.


Asunto(s)
Tasa de Filtración Glomerular/fisiología , Trasplante de Riñón/fisiología , Donantes de Tejidos , Adolescente , Adulto , Anciano , Biopsia , Cadáver , Causas de Muerte , Femenino , Humanos , Riñón/patología , Trasplante de Riñón/patología , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Estudios Retrospectivos , Trasplante Homólogo , Resultado del Tratamiento
20.
Nucleic Acids Res ; 28(7): 1555-63, 2000 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-10710422

RESUMEN

Emphasis was placed in this work on the assessment of biological features of 2,2,4-triaminooxazolone, a major one-electron and(. )OH-mediated oxidation product of guanine. For this purpose, two oligonucleotides that contain a unique oxazolone residue were synthesized. Herein we report the mutagenic potential of oxazolone during in vitro DNA synthesis and its behavior towards DNA repair enzymes. Nucleotide insertion opposite oxazolone, catalyzed by Klenow fragment exo(-)and Taq polymerase indicates that the oxazolone lesion induces mainly dAMP insertion. This suggests that the formation of oxazolone in DNA may lead to G-->T transversions. On the other hand, oxazolone represents a blocking lesion when DNA synthesis is performed with DNA polymerase beta. Interestingly, DNA repair experiments carried out with formamidopyrimidine DNA N -glycosylase (Fpg) and endonuclease III (endo III) show that oxazolone is a substrate for both enzymes. Values of k (cat)/ K (m)for the Fpg-mediated removal of oxidative guanine lesions revealed that 8-oxo-7,8-dihydroguanine is only a slightly better substrate than oxazolone. In the case of endo III-mediated cleavage of modified bases, the present results suggest that oxazolone is a better substrate than 5-OHC, an oxidized pyrimidine base. Finally, MALDI-TOF-MS analysis of the DNA fragments released upon digestion of an oxazolone-containing oligonucleotide by Fpg gave insights into the enzymatic mechanism of oligonucleotide cleavage.


Asunto(s)
Daño del ADN , Reparación del ADN , ADN/biosíntesis , ADN/efectos de los fármacos , Desoxirribonucleasa (Dímero de Pirimidina) , Proteínas de Escherichia coli , Oxazolona/toxicidad , Secuencia de Bases , ADN-Formamidopirimidina Glicosilasa , Endodesoxirribonucleasas/metabolismo , Técnicas In Vitro , Cinética , Mutágenos/toxicidad , N-Glicosil Hidrolasas/metabolismo , Oligodesoxirribonucleótidos/química , Oligodesoxirribonucleótidos/metabolismo , Oxazolona/química , Oxazolona/metabolismo
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