Association of mitochondrial lysyl-tRNA synthetase with HIV-1 GagPol involves catalytic domain of the synthetase and transframe and integrase domains of Pol

Aim. Analyze the interaction between Lysyl-tRNA synthetase (LysRS) and HIV-1 GagPol to know whether a particular N-terminal sequence of mitochondrial LysRS triggers a specific recognition with GagPol. Methods. Yeast two-hybrid analysis, immunoprecipitation. Results. We have shown that LysRS associates with the Pol domain of GagPol. Conclusions. A model of the assembly of the LysRS:tRNA₃Lys:GagPol packaging complex is proposed. Keywords: tRNA₃Lys, lysyl-tRNA synthetase, HIV-1, packaging.Мета. Встановити, чи може N-кінцева послідовність, яка є специфічною для мітохондріальної форми лізил-тРНК синтетази, забезпечувати взаємодію цього ферменту з білком GagPol ВІЛ-1. Методи. Двогібридна дріжджова система, імунопреципітація. Результати. Ми показали що лізил-тРНК синтетаза взаємодіє з доменом Pol білка Gag. Висновки. Запропоновано модель утворення комплексу ЛізРС:тРНК₃Ліз:GagPol. Ключові слова: тРНК₃Ліз, лізил-тРНК синтетаза, ВІЛ-1, збирання віріона.Цель. Выяснить, может ли N-концевая последовательность, являющаяся специфичной для митохондриальной формы лизилтРНК синтетазы, обеспечивать взаимодействие этого фермента с белком GagPol ВИЧ-1. Методы. Двугибридная дрожжевая система, иммунопреципитация Результаты. Мы показали, что лизил-тРНК синтетаза взаимодействует с доменом Pol белка Gag. Выводы. Предложена модель образования комплекса ЛизРС:тРНК₃Лиз:GagPol. Ключевые слова: тРНК₃Лиз, лизил-тРНК синтетаза, ВИЧ-1, сборка вириона

The \u3csup\u3e18\u3c/sup\u3eO-Signal Transfer from Water Vapour to Leaf Water and Assimilates Varies Among Plant Species and Growth Forms

The 18O signature of atmospheric water vapour (δ18OV) is known to be transferred via leaf water to assimilates. It remains, however, unclear how the 18O‐signal transfer differs among plant species and growth forms. We performed a 9‐hr greenhouse fog experiment (relative humidity ≥ 98%) with 18O‐depleted water vapour (−106.7‰) on 140 plant species of eight different growth forms during daytime. We quantified the 18O‐signal transfer by calculating the mean residence time of O in leaf water (MRTLW) and sugars (MRTSugars) and related it to leaf traits and physiological drivers. MRTLW increased with leaf succulence and thickness, varying between 1.4 and 10.8 hr. MRTSugars was shorter in C3 and C4 plants than in crassulacean acid metabolism (CAM) plants and highly variable among species and growth forms; MRTSugars was shortest for grasses and aquatic plants, intermediate for broadleaf trees, shrubs, and herbs, and longest for conifers, epiphytes, and succulents. Sucrose was more sensitive to δ18OV variations than other assimilates. Our comprehensive study shows that plant species and growth forms vary strongly in their sensitivity to δ18OV variations, which is important for the interpretation of δ18O values in plant organic material and compounds and thus for the reconstruction of climatic conditions and plant functional responses

Updating the Dual C and O Isotope—Gas-exchange Model: A Concept to Understand Plant Responses to the Environment and Its Implications for Tree Rings

The combined study of carbon (C) and oxygen (O) isotopes in plant organic matter has emerged as a powerful tool for understanding plant functional responses to environmental change. The approach relies on established relationships between leaf gas exchange and isotopic fractionation to derive a series of model scenarios that can be used to infer changes in photosynthetic assimilation and stomatal conductance driven by changes in environmental parameters (CO2, water availability, air humidity, temperature, nutrients). We review the mechanistic basis for a conceptual model, in light of recently published research, and discuss where isotopic observations do not match our current understanding of plant physiological response to the environment. We demonstrate that (1) the model was applied successfully in many, but not all studies; (2) although originally conceived for leaf isotopes, the model has been applied extensively to tree-ring isotopes in the context of tree physiology and dendrochronology. Where isotopic observations deviate from physiologically plausible conclusions, this mismatch between gas exchange and isotope response provides valuable insights into underlying physiological processes. Overall, we found that isotope responses can be grouped into situations of increasing resource limitation versus higher resource availability. The dual-isotope model helps to interpret plant responses to a multitude of environmental factors

Biodiversidad fitoplanctónica y variables abióticas del embalse Escaba (Tucumán, Argentina)

Con el propósito de analizar la composición fitoplanctónica y variables fisicoquímicas del embalse Escaba, se realizaron muestreos estacionales desde agosto/10 a mayo/12 en la zona limnética (ZL) y desembocaduras de sus tributarios: ríos Chavarría, Las Moras, El Chorro y Singuil (RS). Para la obtención de las muestras se siguieron protocolos convencionales. El agua fue bicarbonatada-cálcica-sódica, alcalina, con temperaturas de 12,5-28 ºC, detectándose una estratificación térmica en primavera y verano. Se obtuvieron los siguientes valores para las variables físico-químicas medidas: transparencia entre 0,12-4,1m, conductividad eléctrica (CE) 83-218 μS/cm, oxígeno disuelto (OD) 2,7-14,5 mg/l, DBO5 <5-183 mg/l, nitrato <0,5-7 mg/l, ortofosfato <0,015-0,22 mg/l y biomasa 6-2511 μg/l de clorofila a. En la relación N/P se observó una deficiencia de fósforo principalmente para verano-otoño. El fitoplancton estuvo representado por especies de Bacillariophyceae (77), Chlorophyta (41), Cyanobacteria (12), Euglenophyta (5) y Dinophyta (1). La densidad algal (ind/ml) varió de 84 (ZL fondo-ago/10) a 6924 (RS-mar/11). La diversidad específica fluctuó entre 0-3,98. Mediante modelos lineales generalizados con distribución binomial negativa se analizaron las variaciones en las abundancias de los grupos algales en función de las estaciones del año, sitios y variables fisicoquímicas. Sólo se registraron cambios con CE, OD, DBO5, compuestos nitrogenados y ortofosfato. Según los resultados la dominancia de Ceratium hirundinella en todas las temporadas coincidió con bajas concentraciones de NO3- con excepción de noviembre 2011 donde sobresalieron las Chlorophyta. Asimismo, los elevados valores de biomasa fueron indicativos de una condición hipertrófica avalada por el nitrógeno total, el fósforo total y transparencia.Fil: Tracanna, Beatriz Concepcion. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Limnología del Noroeste Argentino; Argentina. Fundación Miguel Lillo. Dirección de Botánica. Instituto de Ficología; ArgentinaFil: Martinez de Marco, S.. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Limnología del Noroeste Argentino; Argentina. Fundación Miguel Lillo. Dirección de Botánica. Instituto de Ficología; ArgentinaFil: Taboada, María de Los Ángeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Limnología del Noroeste Argentino; Argentina. Fundación Miguel Lillo. Dirección de Botánica. Instituto de Ficología; ArgentinaFil: Alderete, M.. Fundación Miguel Lillo. Dirección de Botánica. Instituto de Ficología; ArgentinaFil: Mirande, V.. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Limnología del Noroeste Argentino; Argentina. Fundación Miguel Lillo. Dirección de Botánica. Instituto de Ficología; ArgentinaFil: Isasmendí, S.. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Limnología del Noroeste Argentino; ArgentinaVII Congreso Argentino de LimnologíaSan Miguel de TucumanArgentinaUniversidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel LilloFundación Miguel Lill

COMPUTER SIMULATIONS OF POSSIBLE FUTURES FOR TWO FLOCKS OF WHOOPING CRANES

We conducted computer simulations using the program VORTEX (version 7) to project population sizes, growth rates, genetic diversity, and probabilities of extinction over the next 100 years for 2 flocks of whooping cranes (Grus americana), the Aransas/Wood Buffalo population and the experimental Florida population. Standard runs based on best estimates of demographic. genetic, and environmental parameter values were used as a baseline to which several alternative scenarios were compared. Results generally supported the conclusion of the earlier Population Viability Assessment (Mirande et al. 1991) that the AransaslWood Buffalo population will continue to grow steadily with less than a 1 % probability of extinction. It was noted, however, that a combination of negative factors such as shrinking habitat and increased probabilities of catastrophes accompanied by increased mortality rates could put this population at risk. Results for the Florida population were less optimistic. The standard run produced a population growth rate (r) of only 0.0026 for the next 100 years, and this shifted down to -0.0001 over a 200-year time frame. Adult mortality in this flock would have to be about 20% lower than the predicted value (10%) in order to raise growth rates to above r = 0.02. Amount and duration of supplementation of the Florida flock had minimal impacts on the long-tenn growth rate of the flock. It is the enduring rates of mortality, breeding, and disease risk that will have major effects on this population. For example, if disease risks tum out to be greater than the best-estimate scenario, this population could face a relatively high risk of extinction (17%). The formula for success in Florida is lower adult mortality, lower age of first breeding, lower disease risk, and higher productivity than the best-guess estimates. Fortunately, there are some potential management interventions (e.g., predator control, vaccines and health monitoring, selective introductions to balance the sex ratio of the flock) that may be able to push the odds in favor of success

Genomic evolution of staphylococcus aureus during artificial and natural colonization of the human nose

Staphylococcus aureus can colonize the human vestibulum nasi for many years. It is unknown whether and, how S. aureus adapts to this ecological niche during colonization. We determined the short (1 and 3 months) and mid-term (36 months) genomic evolution of S. aureus in natural carriers and artificially colonized volunteers. Eighty-five S. aureus strains were collected from 6 natural carriers during 3 years and 6 artificially colonized volunteers during 1 month. Multi-locus sequence typing (MLST) and single nucleotide polymorphism (SNP) analysis based on whole-genome sequencing (WGS) were carried out. Mutation frequencies within resident bacterial populations over time were quantified using core genome SNP counts (comparing groups of genomes) and pairwise SNP divergence assessment (comparing two genomes from strains originating from one host and sharing identical MLST). SNP counts (within 1-3 months) in all naturally colonizing strains varied from 0 to 757 (median 4). These strains showed random and independent patterns of pairwise SNP divergence (0 to 44 SNPs, median 7). When the different core genome SNP counts over a period of 3 years were considered, the median SNP count was 4 (range 0-26). Host-specific pairwise SNP divergence for the same period ranged from 9 to 57 SNPs (median 20). During short term artificial colonization the mutation frequency was even lower (0-7 SNPs, median 2) and the pairwise SNP distances were 0 to 5 SNPs (median 2). Quantifying mutation frequencies is important for the longitudinal follow-up of epidemics of infections and outbreak management. Random pattern of pairwise SNP divergence between the strains isolated from single carriers suggested that the WGS of multiple colonies is necessary in this context. Over periods up to 3 years, maximum median core genome SNP counts and SNP divergence for the strains studied were 4 and 20 SNPs or lower. During artificial colonization, where median core genome SNP and pairwise SNP distance scores were 2, there is no early stage selection of different genotypes. Therefore, we suggest an epidemiological cut off value of 20 SNPs as a marker of S. aureus strain identity during studies on nasal colonization and also outbreaks of infection

A tryptophan-rich peptide acts as a transcription activation domain

<p>Abstract</p> <p>Background</p> <p>Eukaryotic transcription activators normally consist of a sequence-specific DNA-binding domain (DBD) and a transcription activation domain (AD). While many sequence patterns and motifs have been defined for DBDs, ADs do not share easily recognizable motifs or structures.</p> <p>Results</p> <p>We report herein that the N-terminal domain of yeast valyl-tRNA synthetase can function as an AD when fused to a DNA-binding protein, LexA, and turn on reporter genes with distinct LexA-responsive promoters. The transcriptional activity was mainly attributed to a five-residue peptide, WYDWW, near the C-terminus of the N domain. Remarkably, the pentapeptide <it>per se </it>retained much of the transcriptional activity. Mutations which substituted tryptophan residues for both of the non-tryptophan residues in the pentapeptide (resulting in W₅) significantly enhanced its activity (~1.8-fold), while mutations which substituted aromatic residues with alanine residues severely impaired its activity. Accordingly, a much more active peptide, pentatryptophan (W₇), was produced, which elicited ~3-fold higher activity than that of the native pentapeptide and the N domain. Further study indicated that W₇mediates transcription activation through interacting with the general transcription factor, TFIIB.</p> <p>Conclusions</p> <p>Since W₇shares no sequence homology or features with any known transcription activators, it may represent a novel class of AD.</p

Two new species of Odontostilbe historically hidden under O. microcephala (Characiformes: Cheirodontinae)

Specimens historically identified as Odontostilbe microcephala from the upper rio Paraná and Andean piedmont tributaries of the río Paraguay are reviewed and split in three species. We found that the distribution of O. microcephala is restricted to the Andean slope of the río Paraguay basin. The species is distinguished from congeners with subterminal mouth by the elongate body, usually 10-12 gill rakers on upper branch and smaller horizontal orbital diameter (24.6-32.8 % HL, mean 28.7%). Specimens from upper rio Paraná constitute two new species, diagnosed from other Cheirodontinae by the presence of mesopterygoid teeth, grouped on median portion and forming a continuous row. The new species are distinguished from each other by having premaxillary teeth with five cusps vs. nine cusps and by the number of lamellae in left and right sides of central median raphe of olfactory rosette with 20-21 vs. 11-12.Espécimes historicamente identificados com Odontostilbe microcephala do rio Paraná e tributários do río Paraguay, foram revisados e separados em três espécies. A distribuição de O. microcephala é restrita ao sopé andino da bacia do río Paraguay. A espécie é distinta das congêneres com boca subterminal pela forma alongada, geralmente 10-12 rastros branquiais no ramo superior e menor diâmetro horizontal da órbita (24,6-32,8 % CC, média 28,7%). Espécimes do alto rio Paraná constituem duas espécies novas diagnosticadas de outros Cheirodontinae pela presença de dentes no mesopterigoide, agrupados em sua porção média e formando uma fileira continua. As novas espécies distinguem-se por ter dentes premaxilares com cinco cúspides vs. nove cúspides e pelo número de lamelas nos lados esquerdo e direito da rafe central da roseta olfativa com 20-21 vs. 11-12