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Abstract Background Apolipoprotein E (APOE) genotypes have been suggested to influence cognitive impairment and clinical onset in presenilin-1 (PSEN1) E280A carriers for autosomal dominant Alzheimer’s disease (ADAD). Less is known about their impact on the trajectory of biomarker changes. Neurofilament light chain (NfL), a marker of neurodegeneration, begins to accumulate in plasma about 20 years prior to the clinical onset of ADAD. In this study we investigated the impact of APOE ε4 and ε2 variants on age-related plasma NfL increases and cognition in PSEN1 E280A mutation carriers. Methods We analyzed cross-sectional data from PSEN1 E280A mutation carriers and non-carriers recruited from the Alzheimer’s Prevention Initiative Registry of ADAD. All participants over 18 years with available APOE genotype, plasma NfL, and neuropsychological evaluation were included in this study. APOE genotypes and plasma NfL concentrations were characterized for each participant. Cubic spline models using a Hamiltonian Markov chain Monte Carlo method were used to characterize the respective impact of at least one APOE ε4 or ε2 allele on age-related log-transformed plasma NfL increases. Linear regression models were estimated to explore the impact of APOE ε4 and ε2 variants and plasma NfL on a composite cognitive test score in the ADAD mutation carrier and non-carrier groups. Results Analyses included 788 PSEN1 E280A mutation carriers (169 APOE ε4 + , 114 ε2 +) and 650 mutation non-carriers (165 APOE ε4 + , 80 ε2 +), aged 18–75 years. APOE ε4 allele carriers were distinguished from ε4 non-carriers by greater age-related NfL elevations in the ADAD mutation carrier group, beginning about three years after the mutation carriers’ estimated median age at mild cognitive impairment onset. APOE ε2 allele carriers had lower plasma NfL concentrations than ε2 non-carriers in both the ADAD mutation carrier and non-carrier groups, unrelated to age, and an attenuated relationship between higher NfL levels on cognitive decline in the ADAD mutation carrier group. Conclusions APOE ε4 accelerates age-related plasma NfL increases and APOE ε2 attenuates the relationship between higher plasma NfL levels and cognitive decline in ADAD. NfL may be a useful biomarker to assess clinical efficacy of APOE-modifying drugs with the potential to help in the treatment and prevention of ADAD.

En este trabajo desarrollamos una discusión que busca aclarar y fundamentar la tesis de que el voluntarismo tardo medieval, principalmente el de Duns Escoto, es un factor cuya consideración es indispensable para entender el origen del pensamiento moderno y su deriva en una cultura de la libertad y la innovación como fines en sí mismos. Por voluntarismo entendemos la concepción de la voluntad divina y también humana como una potencia que se determina a sí misma en su acto y que, en este particular sentido, es absolutamente libre, pues no reconoce otra influencia más allá de ella misma. Tanto el acto de la voluntad como su efecto se entienden entonces como un producto enteramente nuevo y original. Realizamos un análisis crítico de este voluntarismo a partir de los textos de Escoto y otros autores medievales, y un análisis histórico-filosófico de su posible influencia en la evolución de la filosofía moderna.

Leptospirosis is a zoonosis with global public health impact, particularly in poor socio-economic settings in tropical regions. Transmitted through urine-contaminated water or soil from rodents, dogs, and livestock, leptospirosis causes over a million clinical cases annually. Risk factors include outdoor activities, livestock production, and substandard housing that foster high densities of animal reservoirs. This One Health study in southern Chile examined Leptospira serological evidence of exposure in people from urban slums, semi-rural settings, and farm settings, using the Extreme Gradient Boosting algorithm to identify key influencing factors. In urban slums, age, shrub terrain, distance to Leptospira-positive households, and neighborhood housing density were contributing factors. Human exposure in semi-rural communities was linked to environmental factors (trees, shrubs, and lower vegetation terrain) and animal variables (Leptospira-positive dogs and rodents and proximity to Leptospira-positive households). On farms, dog counts, animal Leptospira prevalence, and proximity to Leptospira-contaminated water samples were significant drivers. The study underscores that disease dynamics vary across landscapes, with distinct drivers in each community setting. This case study demonstrates how the integration of machine learning with comprehensive cross-sectional epidemiological and geospatial data provides valuable insights into leptospirosis eco-epidemiology. These insights are crucial for informing targeted public health strategies and generating hypotheses for future research.

Abstract Autosomal dominant Alzheimer’s disease (ADAD) is genetically determined, but variability in age of symptom onset suggests additional factors may influence cognitive trajectories. Although apolipoprotein E (APOE) genotype and educational attainment both influence dementia onset in sporadic AD, evidence for these effects in ADAD is limited. To investigate the effects of APOE and educational attainment on age-related cognitive trajectories in ADAD, we analyzed data from 675 Presenilin-1 E280A mutation carriers and 594 non-carriers. Here we show that age-related cognitive decline is accelerated in ADAD mutation carriers who also have an APOE e4 allele compared to those who do not and delayed in mutation carriers who also have an APOE e2 allele compared to those who do not. Educational attainment is protective and moderates the effect of APOE on cognition. Despite ADAD mutation carriers being genetically determined to develop dementia, age-related cognitive decline may be influenced by other genetic and environmental factors.

Metal(loid) salts were used to treat infectious diseases in the past due to their exceptional biocidal properties at low concentrations. However, the mechanism of their toxicity has yet to be fully elucidated. The production of reactive oxygen species (ROS) has been linked to the toxicity of soft metal(loid)s such as Ag(I), Au(III), As(III), Cd(II), Hg(II), and Te(IV). Nevertheless, few reports have described the direct, or ROS-independent, effects of some of these soft-metal(loid)s on bacteria, including the dismantling of iron–sulfur clusters [4Fe-4S] and the accumulation of porphyrin IX. Here, we used genome-wide genetic, proteomic, and biochemical approaches under anaerobic conditions to evaluate the direct mechanisms of toxicity of these metal(loid)s in Escherichia coli. We found that certain soft-metal(loid)s promote protein aggregation in a ROS-independent manner. This aggregation occurs during translation in the presence of Ag(I), Au(III), Hg(II), or Te(IV) and post-translationally in cells exposed to Cd(II) or As(III). We determined that aggregated proteins were involved in several essential biological processes that could lead to cell death. For instance, several enzymes involved in amino acid biosynthesis were aggregated after soft-metal(loid) exposure, disrupting intracellular amino acid concentration. We also propose a possible mechanism to explain how soft-metal(loid)s act as proteotoxic agents.

Abstract Yellow Fever (YF), a mosquito‐borne disease, requires ongoing surveillance and prevention due to its persistence and ability to cause major epidemics, including one that began in Brazil in 2016. Forecasting based on factors influencing YF risk can improve efficiency in prevention. This study aimed to produce weekly forecasts of YF occurrence and incidence in Brazil using weekly meteorological and ecohydrological conditions. Occurrence was forecast as the probability of observing any cases, and incidence was forecast to represent morbidity if YF occurs. We fit gamma hurdle models, selecting predictors from several meteorological and ecohydrological factors, based on forecast accuracy defined by receiver operator characteristic curves and mean absolute error. We fit separate models for data before and after the start of the 2016 outbreak, forecasting occurrence and incidence for all municipalities of Brazil weekly. Different predictor sets were found to produce most accurate forecasts in each time period, and forecast accuracy was high for both time periods. Temperature, precipitation, and previous YF burden were most influential predictors among models. Minimum, maximum, mean, and range of weekly temperature, precipitation, and humidity contributed to forecasts, with optimal lag times of 2, 6, and 7 weeks depending on time period. Results from this study show the use of environmental predictors in providing regular forecasts of YF burden and producing nationwide forecasts. Weekly forecasts, which can be produced using the forecast model developed in this study, are beneficial for informing immediate preparedness measures.

Abstract This paper makes a critical review of educational and operational issues related with pandemic and postpandemic lessons in Latin American higher education institutions (LATAM HEI), as background for uncovering key elements to innovate educational practices in technology-mediated higher education. The authors adapted the reflexive pedagogy framework to conduct in depth analysis of innovation experiences mediated with educational technologies and draw conclusions for curricular and digital transformation of LATAM HEI.

La presente investigación tuvo como objetivo determinar las propiedades psicométricas de la Escala de autopercepción del nivel de logro de los estándares disciplinarios en Educación Física y la Escala de autopercepción del nivel de logro de los estándares pedagógicos y describir los resultados en una muestra de estudiantes universitarios. Metodología: fue de tipo cuantitativa, no experimental de corte transversal. La muestra estuvo constituida por 305 estudiantes de pedagogía en educación física de dos universidades de Santiago de Chile. Los resultados muestran buenos índices de validez y confiabilidad, tanto para la Escala de los Estándares Disciplinarios de Educación Física con tres dimensiones y la Escala de Estándares Pedagógicos con tres dimensiones. También se puede observar que existen diferencias por cursos, donde el estudiantado que está en el último año se presenta con mayor confianza tanto para los conocimientos disciplinarios como pedagógicos. En cuanto a la comparación por sexo, las mujeres poseen mayores niveles de autopercepción de logro. Se concluye que los instrumentos pueden ser utilizados para generar diagnósticos y remediales en el alumnado en relación con los saberes disciplinarios y pedagógicos. Se debe investigar estas variables y su relación con los modelos educativos, programas y mallas curriculares según casa de estudio. Palabras claves: estándar, pedagógicos, disciplinarios, educación física. Abstract. The present research aimed to determine the psychometric properties of the Self-perception Scale of the level of achievement on disciplinary standards in Physical Education and the Self-perception Scale of the level of achievement on pedagogical standards and to describe results in a sample of university students. Methodology: it was quantitative, not experimental cross-sectional. The sample consisted of 305 students of physical education pedagogy from two universities in Santiago de Chile. The results show good rates of validity and reliability for both the Scale of Disciplinary Standards of Physical Education with three dimensions and the Scale of Pedagogical Standards with three dimensions. It can also be observed that there are differences by course, where students who attend the last year are presented with greater confidence for both disciplinary and pedagogical knowledge. Regarding the comparison by sex, women have higher levels of self-perception of achievement. It is concluded that the instruments can be used to generate diagnoses and remedial in the students in relation to disciplinary and pedagogical knowledge. These variables should be investigated and their relationship with educational models, programs and curricula according to study house. Keywords: standard, pedagogical, disciplinary, physical education.

Abstract Background Blastocystis is a typical anaerobic colon protist in humans with controversial pathogenicity and has relation with alterations in the intestinal microbiota composition (dysbiosis), whose eventual indicator is the Firmicutes/Bacteroidetes ratio (F/B ratio); this indicator is also linked to complications such as diabetes, obesity, or inflammatory bowel disease. The present study investigated the prevalence of Blastocystis and its association with Firmicutes/Bacteroidetes ratio in healthy and metabolic diseased subjects. Methods Fecal and blood samples were collected consecutively from 200 healthy subjects and 84 subjects with metabolic disease; Blastocystis and its most frequent subtypes were identified by end-point PCR and the two most representative phyla of the intestinal microbiota Firmicutes and Bacteroidetes by real-time PCR. Results The prevalence of Blastocystis in healthy subjects was 47.0, and 65.48% in subjects with metabolic disease; the most prevalent subtype in the total population was ST3 (28.38%), followed by ST1 (14.86%), ST4, ST5, and ST7 (each one of them with 14.19% respectively), and finally ST2 (8.78%). The low F/B ratio was associated with the prevalence of Blastocystis in the two cohorts FACSA (OR = 3.78 p

Extreme acidophiles thrive in harsh environments characterized by acidic pH, high concentrations of dissolved metals and high osmolarity. Most of these microorganisms are chemolithoautotrophs that obtain energy from low redox potential sources, such as the oxidation of ferrous ions. Under these conditions, the mechanisms that maintain homeostasis of proteins (proteostasis), as the main organic components of the cells, are of utmost importance. Thus, the analysis of protein chaperones is critical for understanding how these organisms deal with proteostasis under such environmental conditions. In this work, using a bioinformatics approach, we performed a comparative genomic analysis of the genes encoding classical, periplasmic and stress chaperones, and the protease systems. The analysis included 35 genomes from iron- or sulfur-oxidizing autotrophic, heterotrophic, and mixotrophic acidophilic bacteria. The results showed that classical ATP-dependent chaperones, mostly folding chaperones, are widely distributed, although they are sub-represented in some groups. Acidophilic bacteria showed redundancy of genes coding for the ATP-independent holdase chaperones RidA and Hsp20. In addition, a systematically high redundancy of genes encoding periplasmic chaperones like HtrA and YidC was also detected. In the same way, the proteolytic ATPase complexes ClpPX and Lon presented redundancy and broad distribution. The presence of genes that encoded protein variants was noticeable. In addition, genes for chaperones and protease systems were clustered within the genomes, suggesting common regulation of these activities. Finally, some genes were differentially distributed between bacteria as a function of the autotrophic or heterotrophic character of their metabolism. These results suggest that acidophiles possess an abundant and flexible proteostasis network that protects proteins in organisms living in energy-limiting and extreme environmental conditions. Therefore, our results provide a means for understanding the diversity and significance of proteostasis mechanisms in extreme acidophilic bacteria.

Me complace presentar la nueva edición de Revista Hábitat Sustentable V12N2, sostenida por la Facultad de Arquitectura Construcción y Diseño, cuyo valioso y nutrido repertorio de artículos colabora desde la investigación a la sustentabilidad en el ambiente construido, en distintas escalas. A través de significativos aportes a la discusión en ámbitos de la economía circular de recursos materiales y ciclo de vida de los edificios, resiliencia de ciudades y edificaciones frente al cambio climático, confort ambiental, habitabilidad, movilidad urbana y suficiencia lumínica, autores y autoras de Latinoamérica (Panamá, Colombia, Brasil, Bolivia, Argentina y Chile) comparten aquí sus propuestas.

Abstract Background Case fatality risk (CFR), commonly referred to as a case fatality ratio or rate, represents the probability of a disease case being fatal. It is often estimated for various diseases through analysis of surveillance data, case reports, or record examinations. Reported CFR values for Yellow Fever vary, offering wide ranges. Estimates have not been found through systematic literature review, which has been used to estimate CFR of other diseases. This study aims to estimate the case fatality risk of severe Yellow Fever cases through a systematic literature review and meta-analysis. Methods A search strategy was implemented in PubMed and Ovid Medline in June 2019 and updated in March 2021, seeking reported severe case counts, defined by fever and either jaundice or hemorrhaging, and the number of those that were fatal. The searches yielded 1,133 studies, and title/abstract review followed by full text review produced 14 articles reporting 32 proportions of fatal cases, 26 of which were suitable for meta-analysis. Four studies with one proportion each were added to include clinical case data from the recent outbreak in Brazil. Data were analyzed through an intercept-only logistic meta-regression with random effects for study. Values of the I2 statistic measured heterogeneity across studies. Results The estimated CFR was 39 % (95 % CI: 31 %, 47 %). Stratifying by continent showed that South America observed a higher CFR than Africa, though fewer studies reported estimates for South America. No difference was seen between studies reporting surveillance data and studies investigating outbreaks, and no difference was seen among different symptom definitions. High heterogeneity was observed across studies. Conclusions Approximately 39 % of severe Yellow Fever cases are estimated to be fatal. This study provides the first systematic literature review to estimate the CFR of Yellow Fever, which can provide insight into outbreak preparedness and estimating underreporting.

The bioleaching process is carried out by aerobic acidophilic iron-oxidizing bacteria that are mainly mesophilic or moderately thermophilic. However, many mining sites are located in areas where the mean temperature is lower than the optimal growth temperature of these microorganisms. In this work, we report the obtaining and characterization of two psychrotolerant bioleaching bacterial strains from low-temperature sites that included an abandoned mine site in Chilean Patagonia (PG05) and an acid rock drainage in Marian Cove, King George Island in Antarctic (MC2.2). The PG05 and MC2.2 strains showed significant iron-oxidation activity and grew optimally at 20°C. Genome sequence analyses showed chromosomes of 2.76 and 2.84 Mbp for PG05 and MC2.2, respectively, and an average nucleotide identity estimation indicated that both strains clustered with the acidophilic iron-oxidizing bacterium Acidithiobacillus ferrooxidans. The Patagonian PG05 strain had a high content of genes coding for tolerance to metals such as lead, zinc, and copper. Concordantly, electron microscopy revealed the intracellular presence of polyphosphate-like granules, likely involved in tolerance to metals and other stress conditions. The Antarctic MC2.2 strain showed a high dosage of genes for mercury resistance and low temperature adaptation. This report of cold-adapted cultures of the At. ferrooxidans species opens novel perspectives to satisfy the current challenges of the metal bioleaching industry.

En tiempos en que el planeta da muestras evidentes de la sobrecarga de nuestra huella ecológica, cuando la demanda y servicios de la naturaleza supera con creces su biocapacidad, se hace urgente generar un punto de inflexión, ya que existe suficiente evidencia científica para afirmar que nos acercamos al peligroso límite del punto de no retorno.

Este artículo presenta un panorama de las diversas investigaciones e intervenciones educativas referidas a la robótica educativa y aprendizaje STEAM. Para esto se llevó a cabo una investigación documental, cualitativa interpretativa, en bases de datos especializadas. Se utilizaron los descriptores: robótica educativa, aprendizaje-robótica, STEAM-robótica, habilidades STEAM y pensamiento computacional. Como resultado se obtuvo el análisis de 105 documentos publicados del 2005 al 2019, se clasificaron de acuerdo con el idioma, ubicación geográfica, nivel educativo, tipo de estudio, temporalidad y tecnología utilizada. Las experiencias educativas se registran principalmente en el nivel primaria y secundaria. Se destacan los beneficios en cuanto al desarrollo de competencias de comunicación, trabajo en equipo, creatividad y resolución de problemas. Las metodologías didácticas empleadas son aprendizaje basado en problemas, proyectos y aprendizaje colaborativo, vivencial y lúdico, relacionadas con teorías construccionistas.

Abstract Background Berry size is considered as one of the main selection criteria in table grapes breeding programs, due to the consumer preferences. However, berry size is a complex quantitive trait under polygenic control, and its genetic determination of berry weight is not yet fully understood. The aim of this work was to perform marker discovery using a transcriptomic approach, in order to identify and characterize SNP and InDel markers associated with berry size in table grapes. We used an integrative analysis based on RNA-Seq, SNP/InDel search and validation on table grape segregants and varieties with different genetic backgrounds. Results Thirty SNPs and eight InDels were identified using a transcriptomic approach (RNA-Seq). These markers were selected from SNP/InDel found among segregants from a Ruby x Sultanina population with contrasting phenotypes for berry size. The set of 38 SNP and InDel markers was distributed in eight chromosomes. Genotype-phenotype association analyses were performed using a set of 13 RxS segregants and 41 table grapes varieties with different genetic backgrounds during three seasons. The results showed several degrees of association of these markers with berry size (10.2 to 30.7%) as other berry-related traits such as length and width. The co-localization of SNP and /or InDel markers and previously reported QTLs and candidate genes associated with berry size were analysed. Conclusions We identified a set of informative and transferable SNP and InDel markers associated with berry size. Our results suggest the suitability of SNPs and InDels as candidate markers for berry weight in seedless table grape breeding. The identification of genomic regions associated with berry weight in chromosomes 8, 15 and 17 was achieved with supporting evidence derived from a transcriptome experiment focused on SNP/InDel search, as well as from a QTL-linkage mapping approach. New regions possibly associated with berry weight in chromosomes 3, 6, 9 and 14 were identified.

Abstract Background The bacterial genus Exiguobacterium includes several species that inhabit environments with a wide range of temperature, salinity, and pH. This is why the microorganisms from this genus are known generically as polyextremophiles. Several environmental isolates have been explored and characterized for enzyme production as well as for bioremediation purposes. In this line, toxic metal(loid) reduction by these microorganisms represents an approach to decontaminate soluble metal ions via their transformation into less toxic, insoluble derivatives. Microbial-mediated metal(loid) reduction frequently results in the synthesis of nanoscale structures—nanostructures (NS) —. Thus, microorganisms could be used as an ecofriendly way to get NS. Results We analyzed the tolerance of Exiguobacterium acetylicum MF03, E. aurantiacum MF06, and E. profundum MF08 to Silver (I), gold (III), and tellurium (IV) compounds. Specifically, we explored the ability of cell-free extracts from these bacteria to reduce these toxicants and synthesize NS in vitro, both in the presence or absence of oxygen. All isolates exhibited higher tolerance to these toxicants in anaerobiosis. While in the absence of oxygen they showed high tellurite- and silver-reducing activity at pH 9.0, whereas AuCl4 − which was reduced at pH 7.0 in both conditions. Given these results, cell-free extracts were used to synthesize NS containing silver, gold or tellurium, characterizing their size, morphology and chemical composition. Silver and tellurium NS exhibited smaller size under anaerobiosis and their morphology was circular (silver NS), starred (tellurium NS) or amorphous (gold NS). Conclusions This nanostructure-synthesizing ability makes these isolates interesting candidates to get NS with biotechnological potential.

Abstract Background Gibberellins (GA3) are the most sprayed growth regulator for table grape production worldwide, increasing berry size of seedless varieties through pericarp cell expansion. However, these treatments also exacerbate berry drop, which has a detrimental effect on the postharvest quality of commercialized clusters. Several studies have suggested that pedicel stiffening caused by GA3 would have a role in this disorder. Nevertheless, transcriptional and phenotypic information regarding pedicel responses to GA3 is minimal. Results Characterization of responses to GA3 treatments using the lines L23 and Thompson Seedless showed that the former was up to six times more susceptible to berry drop than the latter. GA3 also increased the diameter and dry matter percentage of the pedicel on both genotypes. Induction of lignin biosynthesis-related genes by GA3 has been reported, so the quantity of this polymer was measured. The acetyl bromide method detected a decreased concentration of lignin 7 days after GA3 treatment, due to a higher cell wall yield of the isolated fractions of GA3-treated pedicel samples which caused a dilution effect. Thus, an initial enrichment of primary cell wall components in response to GA3 was suggested, particularly in the L23 background. A transcriptomic profiling was performed to identify which genes were associated with these phenotypic changes. This analysis identified 1281 and 1787 genes differentially upregulated by GA3 in L23 and cv. Thompson Seedless, respectively. Concomitantly, 1202 and 1317 downregulated genes were detected in L23 and cv. Thompson Seedless (FDR

Yellow fever (YF) is an endemic mosquito-borne disease in Brazil, though many locations have not observed cases in recent decades. Some locations with low disease burden may resemble locations with higher disease burden through environmental and ecohydrological characteristics, which are known to impact YF burden, motivating increased or continued prevention measures such as vaccination, mosquito control or surveillance. This study aimed to use environmental characteristics to estimate vulnerability to observing high YF burden among all Brazilian municipalities. Vulnerability was defined in three categories based on yearly incidence between 2000 and 2017: minimal, low and high vulnerability. A cumulative logit model was fit to these categories using environmental and ecohydrological predictors, selecting those that provided the most accurate model fit. Per cent of days with precipitation, mean temperature, biome, population density, elevation, vegetation and nearby disease occurrence were included in best-fitting models. Model results were applied to estimate vulnerability nationwide. Municipalities with highest probability of observing high vulnerability was found in the North and Central-West (2000–2016) as well as the Southeast (2017) regions. Results of this study serve to identify specific locations to prioritize new or ongoing surveillance and prevention of YF based on underlying ecohydrological conditions.

Introduction: Hepatic encephalopathy (HE) is the most common neuropsychiatric syndrome secondary to portal hypertension. It usually responds to medical treatment, but sometimes HE is refractory (RHE) to usual treatment. In some patients it may be important to consider management alternatives. Endovascular therapy (ET) could be a therapeutic option in selected cases that is performed with very low frequency and the evidence is scarce. Objectives: To present our experience in the management of RHE with ET. Methods: The pre and post-procedure clinical characteristics of 10 patients with RHE undergoing splenic vein embolization (n: 5) or porto-systemic bypass embolization (n: 5) between 2009-2019 were retrospectively analyzed. Results: 7/10 were men, average age 67 years (62-79), in 70% the cause of cirrhosis was NASH, the Child Pugh average score was B (8 points), (6-11) and MELD-Na was 13 points, (9-20), in 5 patients the ammonia prior to the procedure was 134 mmol / l (range: 90-180, VN

Dormancy is an adaptive strategy developed by temperate perennial crops to protect overwinter tissues from unfavorable environmental conditions. Sweet cherry (Prunus avium L.), a member of the Rosaceae family, requires chilling to overcome dormancy. The time of harvest is directly correlated with chilling requirements in sweet cherries. Consequently, early and late season varieties have low and high chilling requirements, respectively. There is evidence that the expression of dormancy-related genes is regulated by DNA methylation. In this work, methylation-sensitive amplified polymorphism (MSAP) was applied to study genome-wide DNA methylation changes associated with dormancy in two low-chill varieties, ‘Royal Dawn’ and ‘Glen Red’, and one high-chill variety, ‘Kordia’. Our primary results suggest that the occurrence of progressive DNA demethylation is associated with chilling accumulation during dormancy in the three varieties, independent of their chilling requirements. Genes were identified with different methylation status changes, detected by MSAP, related to cell wall remodeling and energy metabolism. Several MSAP profiles among the varieties were observed, suggesting that fine epigenetic control is required to coordinate hormonal and environmental signals that induce dormancy and its release.

Blastocystis is a parasite commonly found in the gut of humans and animals; there are 22 known subtypes (STs). STs 1-9 and 12 have been found in humans. This parasite has a faecal-oral route of transmission; its high infection prevalence in developing countries is due to poor hygiene practices, exposure to infected animals, and intake of contaminated water or food. Its pathogenicity has not been established, because it has been found in symptomatic and asymptomatic patients. The goal of this study was to analyze the frequency of Blastocystis and its subtypes (1, 2, 3, 4, 5, and 7), and assess the relationship between these subtypes and abdominal pain and distension. 202 university students participated in this study. A questionnaire was applied to assess the gastrointestinal symptoms, and subsequently the students were asked to provide faecal samples. The presence of parasites was determined by optical microscopy. Blastocystis-positive samples had their DNA extracted and end-point PCR was performed to corroborate the presence of Blastocystis and determine its subtypes. Among the samples, 47.03% were positive according to PCR analysis. The most prevalent subtypes were ST3 (29.79%), ST4 (16.84%), and ST1 (14.89%). We found a relationship between ST1 and abdominal pain (OR = 0.196; CI = 0.0533–0.7318; p = 0.015), and between ST4 and abdominal distension (OR = 0.2928; CI = 0.1017–0.8429; p = 0.023). However, the presence of this parasite and the probable relationship with gastrointestinal symptoms suggest the need to determine its role within intestinal microbiota in order to confirm whether its eradication is really necessary or not.

In the last few years, scattered experiences of the application of additive manufacturing in the construction of buildings using 3D printing with robots or automated equipment have emerged around the world. These use a variety of procedures and suggest relevant advantages for the construction industry. In order to identify the different processes and features in development in this field and to guide future research and applications, this article presents a review of the literature on the main aspects involved in the use of 3D printing in the construction sector. The review includes state-of-the-art material mixtures, printing technologies, and potential uses, as well as a novel analysis of building strategies, management systems, and benefits stated about this new approach for construction. It reveals progressive experimentation regarding diverse features, with challenges related to the consolidation of procedures and this technology’s readiness to participate in the building market.

Corneal biomechanics aims to establish the physico-mathematical bases that allow for predicting the corneal response to physiological and pathological situations by creating models of tissue behavior. Determining the characteristic parameters of these models is a formidable challenge in the biomechanical modeling process. To contribute to corneal tissue characterization, an experimental set-up was designed, built and tested to study corneal behavior by applying changes in pressure. The elastic constants of porcine corneas were determined, and a Young’s modulus of 0.188 MPa and 26.22% hysteresis were obtained. A computational cornea model was developed to analyze the influence of different factors. Minor variations in the applied conditions were found for apical displacement and pachymetry, and the corneal behavior was reproduced. However, the optical power behavior was affected by variations in the applied conditions, and the experimentally obtained data could not be reproduced. Despite its importance, this parameter has not been analyzed in-depth by other studies, which shows that the quality of a biomechanical cornea model should not be evaluated only by apical displacement.

Purpose: This study aims to analyze travel choices made by air transportation users in multi airport regions because it is a crucial component when planning passenger redistribution policies. The purpose of this study is to find a utility function which makes it possible to know the variables that influence users’ choice of the airports on routes to the main cities in the Colombian territory. Design/methodology/approach: This research generates a Multinomial Logit Model (MNL), which is based on the theory of maximizing utility, and it is based on the data obtained on revealed and stated preference surveys applied to users who reside in the metropolitan area of Aburrá Valley (Colombia). This zone is the only one in the Colombian territory which has two neighboring airports for domestic flights. The airports included in the modeling process were Enrique Olaya Herrera (EOH) Airport and José María Córdova (JMC) Airport. Several structure models were tested, and the MNL proved to be the most significant revealing the common variables that affect passenger airport choice include the airfare, the price to travel the airport, and the time to get to the airport. Findings and Originality/value: The airport choice model which was calibrated corresponds to a valid powerful tool used to calculate the probability of each analyzed airport of being chosen for domestic flights in the Colombian territory. This is done bearing in mind specific characteristic of each of the attributes contained in the utility function. In addition, these probabilities will be used to calculate future market shares of the two airports considered in this study, and this will be done generating a support tool for airport and airline marketing policies.

Han pasado casi seis meses de la publicación de nuestro último número, junio 2019, donde nada hacía presagiar el escenario que vivimos hoy en el país. Un Chile convulsionado, con una explosión social sin precedente, resultado de una crisis multidimensional acumulada en el tiempo basada principalmente en una abismante desigualdad social, económica y ambiental, los pilares fundamentales de los principios de la sustentabilidad.

Significant differences in softening rate have been reported between melting flesh in peach and nectarine varieties. This trait seems to be controlled by several genes. We aimed to identify candidate genes involved in fruit softening rate by integrating quantitative trait loci (QTL) and expression QTL (eQTL) analyses, comparing siblings with contrasting softening rates. We used a segregating population derived from nectarine cv. ‘Venus’ selfing, which was phenotyped for softening rate during three seasons. Six siblings with high (HSR) and six with low softening rate (LSR) were sequenced using RNA-Seq. A group of 5,041 differentially expressed genes was identified. Also, we found a QTL with a LOD (logarithm of odds) score of 9.7 on LG4 in all analyzed seasons. Furthermore, we detected 1,062 eQTLs, of which 133 were found co-localizing with the identified QTL. Gene Ontology (GO) analysis showed ‘Response to auxin’ as one the main over-represented categories. Our findings suggest over-expression of auxin biosynthetic related genes in the HSR group, which implies a higher expression and/or accumulation of auxin, thereby triggering fast softening. Conversely, the LSR phenotype might be explained by an altered auxin-homeostasis associated with low auxin levels. This work will contribute to unraveling the genetic mechanisms responsible for the softening rate in peaches and nectarines and lead to the development of molecular markers.

Las muertes provocadas por la contaminación ambiental son un problema de salud pública en incremento. La mayoría de las muertes prematuras provocadas por la contaminación son enfermedades no transmisibles, como enfermedad pulmonar obstructiva crónica, diabetes tipo 2, enfermedades cardiovasculares y cáncer. Estas son consideradas enfermedades complejas por su multicausalidad y los diversos mecanismos involucrados en su aparición y evolución. El conocimiento del mecanismo de producción de la enfermedad, y la identificación de biomarcadores asociados a enfermedad está avanzando gracias al avance de la tecnología, y específicamente de la tecnología aplicada a medición e interpretación de componentes moleculares: las tecnologías “ÓMICAS”. Estas han permitido identificar causas celulares de algunas enfermedades complejas: variantes genéticas de susceptibilidad o protección a agentes contaminantes (Genómica), así como cambios sobre el ADN (Epigenómica) y sus efectos en el proceso de transcripción de genes específicos de reparación, metabolismo o bien RNA no codificante asociado a enfermedades (Transcriptómica); además la Proteómica y la Metabolómica aportan constante información sobre las proteínas y metabolitos involucrados en los procesos de enfermedad. Paralelo al desarrollo de las tecnologías ómicas ha evolucionado la bioinformática, que ha permitido la interpretación de los resultados de mediciones de cientos de moléculas para organizarlos en redes que traducen las relaciones entre ellas. Las tecnologías ómicas se aplican principalmente para determinar modelos de riesgo de enfermedad en base a estudios poblacionales, pero también la información del genoma, transcriptoma, el epigenoma, el microbioma, el proteoma y el metaboloma se utilizarán para ayudar a descifrar la enfermedad a fin de facilitar el pronóstico y guiar el tratamiento de pacientes, ayudando a la medicina individualizada y medicina de precisión. Sin embargo, su aplicación clínica está aún limitada por el costo y las implicaciones técnicas, regulatorias y éticas.

Microorganism survival in the presence of toxic substances such as metal(loid)s lies chiefly on their ability to resist (or tolerate) such elements through specific resistance mechanisms. Among them, toxicant reduction has attracted the attention of researchers because metal(loid)-reducing bacteria are being used to recover and/or decontaminate polluted sites. Particularly, our interest is to analyze the toxicity of gold and tellurium compounds for the environmental microorganism Enterobacter cloacae MF01 and also to explore the generation of nanostructures to be used in future biotechnological processes. Resistance of E. cloacae MF01 to gold and tellurium salts as well as the putative mechanisms involved -both in aerobic and anaerobic growth conditions- was evaluated. These metal(loid)s were selected because of their potential application in biotechnology. Resistance to auric tetrachloride acid (HAuCl4) and potassium tellurite (K2TeO3) was assessed by determining areas of growth inhibition, minimum inhibitory concentrations, and growth curves as well as by viability tests. E. cloacae MF01 exhibited higher resistance to HAuCl4 and K2TeO3 under aerobic and anaerobic conditions, respectively. In general, their toxicity is mediated by the generation of reactive oxygen species and by a decrease of intracellular reduced thiols (RSH). To assess if resistance implies toxicant reduction, intra- and extra-cellular toxicant-reducing activities were evaluated. While E. cloacae MF01 exhibited intra- and extra-cellular HAuCl4-reducing activity, tellurite reduction was observed only intracellularly. Then, Au- and Te-containing nanostructures (AuNS and TeNS, respectively) were synthesized using crude extracts from E. cloacae MF01 and their size, morphology, and chemical composition was evaluated.

Cardiac fibroblasts (CFs) contribute to theinflammatory response to tissue damage, secreting both pro- and anti-inflammatory cytokines and chemokines. Interferon beta (IFN-β) induces the phosphorylation of signal transducer and activator of transcription (STAT) proteins through the activation of its own receptor, modulating the secretion of cytokines and chemokines which regulate inflammation. However, the role of IFN-β and STAT proteins in modulating the inflammatory response of CF remains unknown. CF were isolated from adult male rats and subsequently stimulated with IFN-β to evaluate the participation of STAT proteins in secreting chemokines, cytokines, cell adhesion proteins expression and in their capacity to recruit neutrophils. In addition, in CF in which the TRL4 receptor was pre-activated, the effect of INF-β on the aforementioned responses was also evaluated. Cardiac fibroblasts stimulation with IFN-β showed an increase in STAT1, STAT2, and STAT3 phosphorylation. IFN-β stimulation through STAT1 activation increased proinflammatory chemokines MCP-1 and IP-10 secretion, whereas IFN-β induced activation of STAT3 increased cytokine secretion of anti-inflammatory IL-10. Moreover, in TLR4-activated CF, IFN-β through STAT2 and/or STAT3, produced an anti-inflammatory effect, reducing pro-IL-1β, TNF-α, IL-6, MCP-1, and IP-10 secretion; and decreasing neutrophil recruitment by decreasing ICAM-1 and VCAM-1 expression. Altogether, our results indicate that IFN-β exerts both pro-inflammatory and anti-inflammatory effects in non-stimulated CF, through differential activation of STAT proteins. When CF were previously treated with an inflammatory agent such as TLR-4 activation, IFN-β effects were predominantly anti-inflammatory.

Nos complace presentar un nuevo número de revista Hábitat Sustentable, el cual recoge un repertorio de artículos que, desde una perspectiva latino e iberoamericana, aportan conocimiento relevante en ámbitos de la eficiencia energética y sustentabilidad ambiental. Destacamos, además, que esta divulgación coincide, con el exitoso lanzamiento en nuestra Universidad del primer Centro Interdisciplinario para la Productividad y Construcción Sustentable, Nodo Sur. CIPYCS, cofinanciado por CORFO y liderado por la UBB, Pontificia Universidad Católica, Universidad de Talca y Universidad Católica del Norte, en colaboración con otra importante red de universidades y empresas nacionales. Esta importante iniciativa, única en Latinoamérica, centra sus objetivos y focos estratégicos en el desarrollo de nuevos materiales, sistemas constructivos y productos sustentables; construcción en madera, productividad, calidad y resiliencia. En general, en el desarrollo de productos con atributos diferenciadores de sustentabilidad y productividad, en línea con los desafíos país en dichas materias. Esta apuesta, busca ser un vehículo que aglutina conocimientos y capacidades habilitantes para un conocimiento transferible, otro aporte sin duda de la investigación aplicada a la sustentabilidad del ambiente construido y calidad de vida de las personas.

Microbes are suitable candidates to recover and decontaminate different environments from soluble metal ions, either via reduction or precipitation to generate insoluble, non-toxic derivatives. In general, microorganisms reduce toxic metal ions generating nanostructures (NS), which display great applicability in biotechnological processes. Since the molecular bases of bacterial reduction are still unknown, the search for new -environmentally safe and less expensive- methods to synthesize NS have made biological systems attractive candidates. Here, 47 microorganisms isolated from a number of environmental samples were analyzed for their tolerance or sensitivity to 19 metal(loid)s. Ten of them were highly tolerant to some of them and were assessed for their ability to reduce these toxicants in vitro. All isolates were analyzed by 16S rRNA gene sequencing, fatty acids composition, biochemical tests and electron microscopy. Results showed that they belong to the Enterobacter, Staphylococcus, Acinetobacter, and Exiguobacterium genera. Most strains displayed metal(loid)-reducing activity using either NADH or NADPH as cofactor. While Acinetobacter schindleri showed the highest tellurite (TeO32-) and tetrachloro aurate (AuCl4-) reducing activity, Staphylococcus sciuri and Exiguobacterium acetylicum exhibited selenite (SeO32-) and silver (Ag+) reducing activity, respectively. Based on these results, we used these bacteria to synthetize, in vivo and in vitro Te, Se, Au, and Ag-containing nanostructures. On the other hand, we also used purified E. cloacae glutathione reductase to synthesize in vitro Te-, Ag-, and Se-containing NS, whose morphology, size, composition, and chemical composition were evaluated. Finally, we assessed the putative anti-bacterial activity exhibited by the in vitro synthesized NS: Te-containing NS were more effective than Au-NS in inhibiting Escherichia coli and Listeria monocytogenes growth. Aerobically synthesized TeNS using MF09 crude extracts showed MICs of 45- and 66- μg/ml for E. coli and L. monocytogenes, respectively. Similar MIC values (40 and 82 μg/ml, respectively) were observed for TeNS generated using crude extracts from gorA-overexpressing E. coli. In turn, AuNS MICs for E. coli and L. monocytogenes were 64- and 68- μg/ml, respectively.

Hantavirus disease in America has been recognizable because of its rapid progression in clinical cases, occurrence in previously healthy young adults, and high case fatality rate. Hantavirus disease has been proposed now to define the diversity of clinical manifestations. Since 1995, a total of 902 cases of hantavirus pulmonary syndrome have been reported in Chile, caused by Andes virus (ANDV), with overall fatality of 32%. This report describes the sero-epidemiology of hantavirus in apparently healthy people in rural and urban slum communities from southern Chile. Ten of 934 samples yielded a positive result resulting in a seroprevalence of 1.07% (95% confidence intervals: 0.05%–2.0%). A higher proportion of positive samples was found among individuals from rural villages (1.3%) and slums (1.5%) compared with farms (0.5%). Seropositivity was associated with age (p = 0.011), low education level (p = 0.006) and occupations linked to the household (homemaker, retired, or student) (p = 0.016). No evidence of infection was found in 38 sigmodontinae rodents trapped in the peri-domestic environment. Our findings highlight that exposure risk was associated with less documented risk factors, such as women in slum and rural villages, and the occurrence of infection that may have presented as flu-like illness that did not require medical attention or was misdiagnosed.

Los endofenotipos son rasgos presentes antes de la aparición de un trastorno y podrían ser útiles para identificar genes de susceptibilidad. Se determinó si personas con esquizofrenia y sus familiares de primer grado no afectados tenían un desempeño menor que los controles en la Tarea de Multitransformación de Expresión Emocional, que mide reconocimiento de emociones faciales. Las personas con esquizofrenia y sus familiares mostraron menor sensibilidad o requirieron más intensidad para identificar emociones que los controles. La exactitud para identificar emociones fue similar entre familiares y controles, pero menor en aquellos con esquizofrenia. Esto sugiere que la sensibilidad para el reconocimiento de emociones faciales es un endofenotipo de la esquizofrenia.

Sumario

Summary: Background: Leptospirosis is a globally important zoonotic disease caused by pathogenic Leptospira, and outbreaks typically follow heavy rainfall and flooding. This study examined the knowledge and perceptions concerning leptospirosis, factors associated with environmental hygiene and sanitation, and the presence of Leptospira in water samples from households with or without a history of the disease in the parish of St. Mary, Jamaica. Methods: The study employed a cross-sectional design in 43 communities within the parish of St. Mary, Jamaica between September 2008 and March 2009. Households that had at least one confirmed case of leptospirosis during the 2005 or 2007 outbreaks were assessed for living conditions, environmental hygiene, and for knowledge and risk perceptions about leptospirosis. A parallel sampling scheme was used for households with no reported cases during the outbreak years. Results: Almost 97% of the participants reported having heard of leptospirosis; however, less than 40% of respondents from households with a history of leptospirosis agreed that leptospirosis was a problem in the parish. Among households without a history of leptospirosis, this perception was greater in urban/peri-urban households than in rural households (59% vs. 21%; p = 0.04). Risk behaviors or living conditions were common; however, there was a high level of awareness about the health risks associated with flooding. Among households with history of leptospirosis, the perception that nothing can be done to control rodents was significantly higher (p

BACKGROUND:Leptospirosis is a neglected zoonosis affecting animals and humans caused by infection with Leptospira. The bacteria can survive outside of hosts for long periods of time in soil and water. While identification of Leptospira species from human cases and animal reservoirs are increasingly reported, little is known about the diversity of pathogenic Leptospira species in the environment and how surveillance of the environment might be used for monitoring and controlling disease. METHODS AND FINDINGS:Water samples (n = 104) were collected from the peri-domestic environment of 422 households from farms, rural villages, and urban slums participating in a broader study on the eco-epidemiology of leptospirosis in the Los Rios Region, Chile, between October 2010 and April 2012. The secY region of samples, previously detected as pathogenic Leptospira by PCR, was amplified and sequenced. Sequences were aligned using ClustalW in MEGA, and a minimum spanning tree was created in PHYLOViZ using the goeBURST algorithm to assess sequence similarity. Sequences from four clinical isolates, 17 rodents, and 20 reference strains were also included in the analysis. Overall, water samples contained L. interrogans, L. kirschneri, and L. weilii, with descending frequency. All species were found in each community type. The distribution of the species differed by the season in which the water samples were obtained. There was no evidence that community-level prevalence of Leptospira in dogs, rodents, or livestock influenced pathogen diversity in the water samples. CONCLUSIONS:This study reports the presence of pathogenic Leptospira in the peri-domestic environment of households in three community types and the differences in Leptospira diversity at the community level. Systematic environmental surveillance of Leptospira can be used for detecting changes in pathogen diversity and to identify and monitor contaminated areas where an increased risk of human infection exists.

The tellurium oxyanion tellurite (TeO32-) is extremely harmful for most organisms. It has been suggested that a potential bacterial tellurite resistance mechanism would consist of an enzymatic, NAD(P)H-dependent, reduction to the less toxic form elemental tellurium (Te0). To date, a number of enzymes such as catalase, type II NADH dehydrogenase and terminal oxidases from the electron transport chain, nitrate reductases, and dihydrolipoamide dehydrogenase (E3), among others, have been shown to display tellurite-reducing activity. This activity is generically referred to as tellurite reductase (TR). Bioinformatic data resting on some of the abovementioned enzymes enabled the identification of common structures involved in tellurite reduction including vicinal catalytic cysteine residues and the FAD/NAD(P)+-binding domain, which is characteristic of some flavoproteins. Along this line, thioredoxin reductase (TrxB), alkyl hydroperoxide reductase (AhpF), glutathione reductase (GorA), mercuric reductase (MerA), NADH: flavorubredoxin reductase (NorW), dihydrolipoamide dehydrogenase, and the putative oxidoreductase YkgC from Escherichia coli or environmental bacteria were purified and assessed for TR activity. All of them displayed in vitro TR activity at the expense of NADH or NADPH oxidation. In general, optimal reducing conditions occurred around pH 9-10 and 37 °C.Enzymes exhibiting strong TR activity produced Te-containing nanostructures (TeNS). While GorA and AhpF generated TeNS of 75 nm average diameter, E3 and YkgC produced larger structures (> 100 nm). Electron-dense structures were observed in cells over-expressing genes encoding TrxB, GorA and YkgC.

Estudio descriptivo, transversal, realizado en Santiago de Chile. Tuvo como objetivo evaluar el razonamiento científico y comunicación oral y escrita en el licenciado en enfermería. Muestra constituida por 37 estudiantes licenciados en la carrera de enfermería. La investigación fue diseñada en tres etapas: I) creación y validación del instrumento; II) capacitación del equipo de docentes participantes para la aplicación uniforme del instrumento; III) aplicación del instrumento y análisis de datos. Los principales resultados muestran porcentajes diferentes de competencia obtenidos por los licenciados en enfermería, prevaleciendo el logro del razonamiento científico (83,16%); seguido de la comunicación oral y escrita (78,37%). Esta investigación muestra la utilidad para las Escuelas de Enfermería de implementar un sistema para evaluar el perfil de egresados del grado de licenciado en enfermería que garantice la calidad de la formación.

BACKGROUND:Leptospirosis is an epidemic-prone neglected disease that affects humans and animals, mostly in vulnerable populations. The One Health approach is a recommended strategy to identify drivers of the disease and plan for its prevention and control. In that context, the aim of this study was to analyze the distribution of human cases of leptospirosis in the State of Rio Grande do Sul, Brazil, and to explore possible drivers. Additionally, it sought to provide further evidence to support interventions and to identify hypotheses for new research at the human-animal-ecosystem interface. METHODOLOGY AND FINDINGS:The risk for human infection was described in relation to environmental, socioeconomic, and livestock variables. This ecological study used aggregated data by municipality (all 496). Data were extracted from secondary, publicly available sources. Thematic maps were constructed and univariate analysis performed for all variables. Negative binomial regression was used for multivariable statistical analysis of leptospirosis cases. An annual average of 428 human cases of leptospirosis was reported in the state from 2008 to 2012. The cumulative incidence in rural populations was eight times higher than in urban populations. Variables significantly associated with leptospirosis cases in the final model were: Parana/Paraiba ecoregion (RR: 2.25; CI95%: 2.03-2.49); Neossolo Litolítico soil (RR: 1.93; CI95%: 1.26-2.96); and, to a lesser extent, the production of tobacco (RR: 1.10; CI95%: 1.09-1.11) and rice (RR: 1.003; CI95%: 1.002-1.04). CONCLUSION:Urban cases were concentrated in the capital and rural cases in a specific ecoregion. The major drivers identified in this study were related to environmental and production processes that are permanent features of the state. This study contributes to the basic knowledge on leptospirosis distribution and drivers in the state and encourages a comprehensive approach to address the disease in the animal-human-ecosystem interface.

Con excepcional satisfacción presentamos el octavo número de revista Hábitat Sustentable. Queremos destacar y agradecer el gran interés mostrado en cada convocatoria. Esto da cuenta de que vamos por el camino correcto, asumiendo un compromiso permanente en mejorar la gestión de nuestra publicación. La cobertura y la difusión de este quehacer divulgativo continúan avanzando tras haber sido invitados a sumarnos a la Plataforma Open Access de Revistas Científicas Electrónicas Españolas y Latinoamericanas.

Tagosodes orizicolus (Homoptera: Delphacidae) is one of the main constraints of the rice production in the Neotropics. This planthopper produces severe damages as a phloem feeder, causes mechanical injury during oviposition and vectors the rice hoja blanca virus (RHBV). The main objective of this study was to determine the genetic diversity of T. orizicolus populations from three rice growing regions of Costa Rica, using RAPDs. Individuals from Guanacaste, Parrita, San Carlos and Cali-Colombia, as outgroup, were analyzed using the random primers. Phenetic relationships revealed that the Costa Rican populations were clearly separated from Cali-Colombia, sharing less than 25% similarity. Costa Rican populations were divided into two main branches separated at 30% similarity. The first branch included Guanacaste and San Carlos and the second displayed Parrita. In relation to similarity indexes within groups, the Guanacaste cluster showed the highest (over 50%) and Cali-Colombia was the most diverse (28%). The correspondence analysis confirmed the clusters of the phenogram and showed close interactions between the Parrita and San Carlos populations. The genetic separation observed could be the result of the geographic isolation among populations, but it could also be explained by the infection with the rickettsia Wolbachia pipientis. This bacterium causes cytoplasmic incompatibility in its host, which results in non-viable progeny when infected males mate with non-infected females, or when insects hosting different strains of Wolbachia mate. Then, a search for Wolbachia in previously described populations of T. orizicolus was initiated. The presence of the bacteria was analyzed by PCR with 16S rDNA-specific primers for Wolbachia. The PCR analyses revealed infections of 86% in the population of San Carlos, 96% in Guanacaste, 37% in Parrita and 100% in Cali-Colombia. Crosses between individuals of T. orizicolus from Parrita and Guanacaste were performed for testing cytoplasmic incompatibility. When infected males were crossed with non-infected females within the same population, a significant reduction in progeny number was obtained as well as when crosses between infected individuals belonging to different populations were performed. These experiments showed cytoplasmic incompatibility not only caused by the presence of Wolbachia within the population, but also by the presence of different strains of the bacteria between populations. Rev. Biol. Trop. 52(3): 795-806. Epub 2004 Dic 15.Tagosodes orizicolus (Homoptera: Delphacidae) es uno de las principales plagas de arroz en el Neotrópico, ya que se alimenta de la savia del floema, realiza incisiones durante la oviposición que dañan los haces vasculares de las hojas y es el vector del virus de la hoja blanca del arroz (RHBV). El objetivo de esta investigación es determinar la diversidad genética de las poblaciones de T. orizicolus de las principales zonas arroceras del Costa Rica. Para ello se analizaron mediante RAPDs individuos de las población de Guanacaste, Parrita y San Carlos y como grupo externo Cali-Colombia. El fenograma mostró que los individuos agruparon de acuerdo a su localidad, observándose que las tres poblaciones costarricenses se separaron de la Colombiana, compartiendo menos del 25% de similaridad. Las poblaciones costarricenses se separaron en dos brazos principales a un 30% de similaridad: el primero incluyó Guanacaste y San Carlos, mientras que el segundo lo constituyó Parrita. El conglomerado de Guanacaste mostró un índice de similaridad del 50% entre individuos mientras que la población de Cali-Colombia fue la más diversa (28%). Finalmente, el análisis de correspondencia confirmó los conglomerados observados en el fenograma y mostró una interacción cercana entre las poblaciones de Parrita y San Carlos. La separación genética observada podría ser el resultado del aislamiento geográfico entre poblaciones pero también podría explicarse por la infección con la rickettsia Wolbachia pipientis. Esta bacteria causa incompatibilidad citoplasmática en sus hospederos, lo cual resulta en una progenie no viable en los cruces entre machos infectados con hembras no infectadas, o cuando ocurren cruces entre insectos infectados con diferentes cepas de Wolbachia. Otro objetivo de esta invsetigación fue determinar por PCR la presencia de Wolbachia en las poblaciones antes mencionadas, utilizando iniciadores específicos para el rADN 16S. Dicho análisis reveló infecciones del 86% en la población de San Carlos, un 96% en Guanacaste, un 37% en Parrita y un 100% en Cali-Colombia. Con el fin de determinar si se presenta incompatibilidad citoplasmática, se llevaron a cabo cruces entre individuos de T. orizicolus de Parrita y Guanacaste. Se observó una reducción significativa en la progenie en los cruces entre machos infectados y hembras no infectadas de una misma población, así como, en los cruces entre individuos infectados pertenecientes a poblaciones diferentes. Estos resultados mostraron incompatibilidad citoplasmática, no sólo causada por la presencia de Wolbachia, sino también por la presencia de diferentes cepas de la bacteria entre poblaciones de T. orizicolus.

El presente artículo muestra resultados acerca de la determinación de la energía contenida y la huella de carbono asociadas al proceso de fabricación de hormigones, en una planta premezcladora en la región del Biobío, Chile, a través de un Análisis de Ciclo de Vida simplificado. El inventario ambiental consideró primordialmente: transporte de materias primas, proceso de dosificación, carguío y despacho de los principales insumos materiales. Para todas estas actividades se cuantificaron consumos energéticos y emisiones de CO2 durante un año de producción, excluyendo consumo energético y huella de carbono corporativa. Al aplicar el “inventario ciclo de vida” (ICV), según IS0 14.040-2006, el caso de estudio mostró que para producir un metro cúbico de hormigón premezclado se requieren 342 MJ, lo que genera una huella de carbono de 26 Kg/CO2. Al comparar este resultado con bases de datos internacionales, el mismo caso demostró ser un 37,5% más bajo en energía contenida y más de un 50% inferior en emisiones de CO2. Esta investigación permitió concluir que el proceso unitario con mayor impacto ambiental desde el punto de vista del consumo energético y emisiones de CO2, está constituido por los transportes indirectos de las materias primas, principalmente áridos, que representan un 46% del total del sistema estudiado.

We investigated the production of ammonium by the photodegradation of dissolved organic matter (DOM) in the coastal upwelling system off central Chile (36°S). The mean penetration of solar radiation (Z1%) between April 2011 and February 2012 was 9.4 m, 4.4 m and 3.2 m for Photosynthetically Active Radiation (PAR; 400-700 nm), UV-A (320-400 nm) and UV-B (280-320 nm), respectively. Ammonium photoproduction experiments were carried out using exudates of DOM obtained from cultured diatom species (Chaetoceros muelleri and Thalassiosira minuscule) as well as natural marine DOM. Diatom exudates showed net photoproduction of ammonium under exposure to UVR with a mean rate of 0.56±0.4 µmol L(-1) h(-1) and a maximum rate of 1.49 µmol L(-1) h(-1). Results from natural marine DOM showed net photoproduction of ammonium under exposure to PAR+UVR ranging between 0.06 and 0.2 µmol L(-1) h(-1). We estimated the potential contribution of photochemical ammonium production for phytoplankton ammonium demand. Photoammonification of diatom exudates could support between 117 and 453% of spring-summer NH4(+) assimilation, while rates obtained from natural samples could contribute to 50-178% of spring-summer phytoplankton NH4(+) requirements. These results have implications for local N budgets, as photochemical ammonium production can occur year-round in the first meters of the euphotic zone that are impacted by full sunlight.

Los desórdenes músculo-esqueléticos son la principal causa de enfermedad profesional en Colombia. Objetivo: fue caracterizar la presencia de síntomas osteomusculares y factores derivados de carga física en trabajadores de una Institución Prestadora de Servicios de Salud de primer nivel en la ciudad de Buga, Colombia. Metodología: Estudio observacional, descriptivo de corte transversal en la población de 39 trabajadores de la empresa en el año 2010. Se recolectaron datos socio-demográficos y laborales. Los síntomas osteomusculares fueron evaluados con el Cuestionario Nórdico de Kourinca. Los factores derivados de carga física fueron determinados con la OSHA Checklist y con el método RULA. Resultados: Los síntomas osteomusculares más prevalentes en los últimos 12 meses fueron: dolor en cuello (70.3%), dolor en dorso (64.9%) y dolor en muñecas y manos (51.4%). En la evaluación de los trabajadores que utilizan computador en el trabajo (n=29) con OSHA Checklist se encontró que pueden existir problemas en área de trabajo en el 75.9%, silla en el 55.2%, accesorios 27.6% y en postura de trabajo en el 24.1%. En la evaluación de trabajadores que no utilizan computador en el trabajo (n=8) por el método RULA se observó que el 55.6% pueden requerir cambios en la tarea y el 44.4 % requieren el rediseño de la tarea. Conclusiones: La prevalencia de síntomas osteomusculares y la carga física obtenida sugiere que esta población está a riesgo de sufrir patología osteomuscular.