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Phytoextraction has been proposed in many papers as a low-cost method for remediating contaminated soil. However, if national regulation is based on total metal(oid) concentrations in soil, phytoextraction is generally infeasible because of the long time required for remediation. Assessing phytoextraction requires the determination of the dynamic rate of metal removal from soil. Phytoextraction may be feasible if the main goal is to reduce the soluble fraction of the metal(oid) with the goal of reducing bioavailability. However, it has been reported that there is a large mass balance mismatch between the reduction of the soluble metal fraction in contaminated soil and metal uptake by plants. Several studies report that the decrease of soluble fraction of metals in soil is higher than can be accounted for by plant uptake. In other words, studies generally overestimate the feasibility of bioavailable contaminant stripping. Therefore, a more rigorous approach is advisable to ensure that papers on bioavailable contaminant stripping include relevant information on mass balances. Furthermore, to implement the concept of bioavailable contaminant stripping, regulations must distinguish between the bioavailable fraction and the total metal concentration in soil. This article is protected by copyright. All rights reserved. Environ Toxicol Chem 2022;00:0-0. © 2022 SETAC.

Newly synthesized membrane proteins pass through the secretory pathway starting at the endoplasmic reticulum and packaged into COPII vesicles to continue to the Golgi apparatus before reaching their membrane of residence. It is known that cargo receptor proteins form part of the COPII complex and play a role in the recruitment of cargo proteins for their subsequent transport through the secretory pathway. The role of cornichon proteins is conserved from yeast to vertebrates, but it is poorly characterized in plants. To study the role of this protein in cellular traffic mechanisms in plants, the mossPhyscomitrium patenshas been selected since it can be studied at the single-cell level. Here, we studied the role of the two moss cornichon homologs in the secretory pathway. Mutant analyzes revealed that cornichon genes regulate different growth processes during the moss life cycle, by controlling auxin transport; with CNIH2 functioning as a specific cargo receptor for the auxin efflux carrier PINA, with the C-terminus of the receptor regulating the interaction and trafficking of PINA.

Diagnosis of Autism Spectrum Conditions (ASC) can be an extended procedure since ASC tend to both vary greatly across individual symptoms and diagnostic pathways with serious challenges to opportune access and diagnosis in low resource settings. We adapted the Q-CHAT-25 for use in a routine health check-ups programme at Chilean primary health clinics by developing a 10-item version of this questionnaire recruiting n = 287 (F: 112/M: 175) participants (Controls: n = 125, F: 58/M: 67; Developmental Delay: n = 149, F: 53/M: 96; Autism Spectrum Conditions: n = 13, F: 1/M: 12). Our findings show that the Q-CHAT-10 can be successfully applied in health-check programmes. The results for the Q-CHAT-10 show high internal consistency (Cronbach’s α: 0.85) and good overall performance, significantly correlating (r = 0.79, p Lay abstract Getting a diagnosis of autism can take long, because autism is different across people, but also because it depends on the way it gets diagnosed. This is especially important in poorer countries or in the case of poor people living in wealthier countries that have significant groups of disadvantaged communities. We adapted a 10-item version of the Q-CHAT-25 questionnaire for use in routine health check-ups programme in Chile and recruited 287 participants under the age of three divided into three groups: Controls (125), Developmental Delay (149) and Autism Spectrum Condition (13). Our results show that a short questionnaire for autism screening can be successfully applied in a health-check programme in poor resource settings. Our results show that our questionnaire had good overall performance, not different to its longer version, the Q-CHAT-25. Our questionnaire was autism specific, with good sensitivity and reliability, and is suitable to be used in a screening setting. This study provides evidence that the implementation of Autism Spectrum Condition screening programmes using the Q-CHAT-10 provides value for money and improves diagnosis of Autism Spectrum Condition in those participating in routine health check-up programmes in developing countries or poor areas of wealthy countries.

The concept of attitude toward soil is emerging, with a slim choice of scales available to collect hard data. There is also a dearth of standard scales to acquire precise data on students’ knowledge of soil. Therefore, the objectives of the present study were: (1) to devise appropriate scales to quantify theoretical soil knowledge and attitude toward soil, and (2) to quantify the effect of laboratory studies and fieldwork on students’ theoretical soil knowledge and attitude toward soil. The study is based on data collected from undergraduate students of the introductory soil science course. Participating students were randomly divided into two groups. Teaching of the control group (n = 38) was classroom-based, while teaching of the intervention group (n = 43) was complemented with laboratory studies and fieldwork. Our test design included a pre-test and post-test. It appears that theoretical soil knowledge and students’ attitude toward soil can be improved using classroom-based education alone, without any need for laboratory or field components. However, future studies would be needed to develop questionnaires covering hands-on soil knowledge to better gauge the impact of lab work and field classes on student learning. The present study is an important step to elaborate reliable scales suitable for quantifying students’ knowledge and attitude toward the soil. It is impossible to test academic assumptions or create theoretical foundations for soil science education without a reliable device to weigh analytical concepts.

Metal contamination of soil has become a serious environmental problem worldwide. Many studies have attempted to infer metal ecotoxicity from soil microbial responses. However, much of the data from these studies tends to be inconsistent and difficult to interpret. We hypothesized that microbial response would be a useful indicator of metal toxicity in soils contaminated by copper mining in Chile. Eighty-four topsoils (0-20 cm) were collected from three areas historically contaminated by copper mining (total Cu: 46-1106 mg kg

All organisms live in close association with a variety of microorganisms called microbiota. Furthermore, several studies support a fundamental role of the microbiota on the host health and homeostasis. In this context, the aim of this work was to determine the structure and diversity of the microbiota associated with the scallop Argopecten purpuratus, and to assess changes in community composition and diversity during the host immune response. To do this, adult scallops were immune challenged and sampled after 24 and 48 h. Activation of the immune response was established by transcript overexpression of several scallop immune response genes in hemocytes and gills, and confirmed by protein detection of the antimicrobial peptide big defensin in gills of Vibrio-injected scallops at 24 h post-challenge. Then, the major bacterial community profile present in individual scallops was assessed by denaturing gradient gel electrophoresis (DGGE) of 16S rDNA genes and dendrogram analyses, which indicated a clear clade differentiation of the bacterial communities noticeable at 48 h post-challenge. Finally, the microbiota structure and diversity from pools of scallops were characterized using 16S deep amplicon sequencing. The results revealed an overall modulation of the microbiota abundance and diversity according to scallop immune status, allowing for prediction of some changes in the functional potential of the microbial community. Overall, the present study showed that changes in the structure and diversity of bacterial communities associated with the scallop A. purpuratus are detected after the activation of the host immune response. Now, the relevance of microbial balance disruption in the immune capacity of the scallop remains to be elucidated.

Scientists around the world have long been searching for effective strategies to reduce the bioavailability of metals in contaminated soils. In case of metal-spiked soils, some studies have proposed gypsum as a soil amendment to alleviate metal phytotoxicity. However, for real field-collected soils, evidence on the efficacy of gypsum as a metal phytotoxicity amendment is limited. Therefore, the present study was designed to examine the effect of gypsum on plant growth in soils polluted by a copper smelter. We grew perennial ryegrass on untreated and gypsum-treated soils (at a dose of 3% by weight) under laboratory conditions. We found that gypsum had no effect on alleviating metal phytotoxicity in our soils. We also demonstrated – for the first time – that gypsum increased the concentrations of soluble metals in the soil, enhancing metal uptake by plants. The calcium ions from gypsum displace metals in the soil exchangeable complex; however, the metals do not get immobilized in soils because gypsum is a neutral salt. While our results contrast with the Terrestrial Biotic Ligand Model, that Model has never been tested on real industrially polluted soils but only on metal-spiked soils. Our main conclusion is that gypsum is ineffective in alleviating metal phytotoxicity in real industrially polluted soils and, moreover, its use is inappropriate as a soil remediation method, because it increases the environmental hazard rather than reducing it. Our study is the very first attempt to recognize that gypsum is a hazardous material when used to ameliorate soils polluted by metals.

Intellectual disability (ID) is a neurodevelopmental disorder characterized by limitations in intellec tual and adaptive functioning, of various etiologies, including genetic causes.to describe genetic studies carried out in a series of children and adolescents with ID of previously undetermined etiology, considering their phenotypic characteristics.Descriptive study of a series of patients with ID aged 6 to 18 years. Clinical records, cognitive assessment results (Wechsler -TADI), and genetic study performed were reviewed. They were classified according to phenotypic characteristics into Group 1 patients without a specific phenotype, Group 2: patients with Angel- man- and Rett-like neurodevelopmental disorders phenotype, and Group 3: patients with difficult- to-control seizures. Group 1 was studied with CMA and Groups 2 and 3 with specific genetic panels.18 patients were described, average age 11 years, male predominance, non-consanguineous parents, and with history of psychomotor retardation. Common comorbidities were epilepsy, autism spectrum disorder (ASD), and behavioral difficulties. Most had a neurological examination without focus and had TADI with very poor developmental ages. In Group 1, there was one patient with a 16p11.2 microdeletion and in Group 3 a duplication of the IQSEC2 gene was found in a patient with difficult-to-control seizures.The phenotypic characteristics allow to guide the choice of specific genetic studies in children and adolescents with ID of previously undetermined etiology to approach the etiological diagnosis.

Pseudomonas syringae pv. actinidiae (Psa) is the causal agent of a bacterial canker in kiwifruit plants and has caused economic losses worldwide. Currently, the primary strategies to control this pathogen include the use of copper-based compounds and even antibiotics. However, the emergence of isolates of Psa that are resistant to these agrochemicals has raised the need for new alternatives to control this pathogen. Bacteriophages have been proposed as an alternative to control bacterial infections in agriculture, including Psa. Here, we show the isolation and characterization of 13 phages with the potential to control Psa infections in kiwifruit plants. The phages were characterized according to their host range and restriction fragment length polymorphism (RFLP) pattern. Four phages were selected according to their lytic effect on the bacteria and their tolerance to different environmental conditions of pH (4&ndash, 7), temperature (4&ndash, 37 &deg, C), and solar radiation exposure (30 and 60 min). The selected phages (CHF1, CHF7, CHF19, and CHF21) were sequenced, revealing a high identity with the podophage of Psa phiPSA2. In vitro assays with kiwifruit leaf samples demonstrated that the mixture of phages reduced the Psa bacterial load within three hours post-application and was able to reduce the damage index in 50% of cases. Similarly, assays with kiwifruit plants maintained in greenhouse conditions showed that these phages were able to reduce the Psa bacterial load in more than 50% of cases and produced a significant decrease in the damage index of treated plants after 30 days. Finally, none of the selected phages were able to infect the other bacteria present in the natural microbiota of kiwifruit plants. These results show that bacteriophages are an attractive alternative to control Psa infections in kiwifruit plants.

Robot-assisted Therapy (RAT) can improve the behavior of children with Autism Spectrum Disorder (ASD) in a spontaneous and entertaining way. There are no previous experiences of this type of inter vention in our country.To describe a clinical experience of using RAT and its impact on the behaviors of a group of children with ASD, in a therapeutic context.Quasi experimental clinical experience type study. 4 children with a clinical diagnosis of ASD were selected, supported by the ADOS-2 (Autism Diagnostic Observation Schedule); aged between 9 and 13 years, and normal IQ according to the WISC-III (Wechsler Intelligence Scale for Children). This study was approved by the Central Metropolitan Ethics Committee. Patients attended 10 structured robot-as sisted therapy sessions, working collaboratively in pairs. Workshop attendance and parent and child satisfaction were evaluated through surveys, the adaptive behavior with the Vineland scale, and so cial interaction with video coding guidelines.Patients presented a very good adherence and satisfaction with the activity. There was an improvement in socialization behaviors and social age. Video-coding showed an increase in social interaction and improvement in the behavior of the pa tients after attending workshops.We observed that the experience with RAT, adapted to the context of a Chilean public health center, was highly attractive and beneficial for patients with ASD, improving core symptoms such as difficulties in social interaction and behavioral problems.

The prevalence of Autism Spectrum Disorder has increased, varying between 0.5 and 1% around the world. The prevalence of ASD in Chile is unknown.To estimate the prevalence of ASD in two urban communes of Santiago, Chile.Cross-sectional epidemiological study. 272 children aged between 18-30 months who attended well-child visits at two Family Health Centers in two urban communes of Santiago participated. Consecutive sampling was used and chil dren who were already being monitored by neurology were excluded. Screening was performed using the Modified Checklist for Autism in Toddlers (M-CHAT). Those children with altered M-CHAT were evaluated by a pediatric neurologist at the San Borja Arriarán Clinical Hospital and diagnosed with ASD according to clinical criteria. The Autism Diagnostic Observation Schedule - Second Ver sion (ADOS-2) was used as a diagnostic complement. The prevalence of ASD was estimated with a 95% confidence interval.44 children had altered M-CHAT; 5 of them were clinically diagno sed with ASD. A 1.95% prevalence of ASD (95% CI 0.81-4.63) was obtained, with a sex distribution of 4 boys per 1 girl.This study is the first estimate of ASD prevalence in two communes of Santiago, Chile. A high prevalence of this condition was observed, which highlights the need for obtaining resources for an early multidisciplinary approach for these patients.

According to the Terrestrial Biotic Ligand Model, other cations might compete with Cu+2 for biotic ligand sites and provide a protective effect. In particular, evidence suggests Zn may alleviative Cu toxicity. No study, to the best of our knowledge, has focused explicitly on the alleviating effect Zn might have on Cu toxicity to soil microorganisms in field-contaminated soils. The aim of this study was to investigate the alleviating effect Zn might have on Cu toxicity to symbiotic nitrogen fixation in agricultural soils affected by copper mining in central Chile. The bioassay estimated the symbiotic nitrogen fixation capacity of a population of rhizobia in a specified soil, using the soil as inocula for Phaseolus vulgaris L. grown in a soil-less system (pots with perlite) irrigated with a sterile nitrogen-free nutrient solution. Among all soil physicochemical characteristics, the Cu/Zn ratio best explained changes in symbiotic nitrogen fixation. The effective concentration 50% (EC50) of Cu/Zn ratio for symbiotic nitrogen was equal to 1.2, with 95% confidence interval of 1.0–1.3. Symbiotic nitrogen fixation decreased with increased Cu/Zn ratio, thus suggesting that Zn alleviates Cu toxicity to nitrogen fixing microorganisms.

The Salar de Huasco is an evaporitic basin located in the Chilean Altiplano, which presents extreme environmental conditions for life, i.e. high altitude (3800 m.a.s.l.), negative water balance, a wide salinity range, high daily temperature changes and the occurrence of the highest registered solar radiation on the planet (> 1200 W m−2). This ecosystem is considered as a natural laboratory to understand different adaptations of microorganisms to extreme conditions. Rhodobacter, an anoxygenic aerobic phototrophic bacterial genus, represents one of the most abundant groups reported based on taxonomic diversity surveys in this ecosystem. The bacterial mat isolate Rhodobacter sp. strain Rb3 was used to study adaptation mechanisms to stress-inducing factors potentially explaining its success in a polyextreme ecosystem. We found that the Rhodobacter sp. Rb3 genome was characterized by a high abundance of genes involved in stress tolerance and adaptation strategies, among which DNA repair and oxidative stress were the most conspicuous. Moreover, many other molecular mechanisms associated with oxidative stress, photooxidation and antioxidants; DNA repair and protection; motility, chemotaxis and biofilm synthesis; osmotic stress, metal, metalloid and toxic anions resistance; antimicrobial resistance and multidrug pumps; sporulation; cold shock and heat shock stress; mobile genetic elements and toxin–antitoxin system were detected and identified as potential survival mechanism features in Rhodobacter sp. Rb3. In total, these results reveal a wide set of strategies used by the isolate to adapt and thrive under environmental stress conditions as a model of polyextreme environmental resistome.

La discapacidad intelectual (DI) es un trastorno del neurodesarrollo manifestado por limitaciones en el funcionamiento intelectual y adaptativo, de etiologías diversas, dentro de las cuales se incluyen las causas genéticas.Objetivo: Describir estudios genéticos realizados en una serie de niños y adolescentes con DI de etiología previamente indeterminada, considerando sus características fenotípicas.Pacientes y Método: Estudio descriptivo de una serie de pacientes con DI de 6 a 18 años. Se revisaron registros clínicos, resultados de evaluación cognitiva (Wechsler-TADI) y estudio genético realizado. Se clasificaron según características fenotípicas en: Grupo 1 pacientes sin fenotipo específico, Grupo 2: pacientes con fenotipo de desórdenes del neurodesarrollo Angelman-Rett like y Grupo 3: pacientes con epilepsia de difícil manejo. Grupo 1 se estudió con microarray cromosómico y Grupos 2 y 3 con paneles genéticos específicos.Resultados: Se describen 18 pacientes, edad promedio 11 años, predominio sexo masculino, de padres no consanguíneos, con antecedente de retraso psicomotor. Comorbilidades frecuentes: epilepsia, rasgos de trastorno espectro autista (TEA) y dificultades conductuales. La mayoría tuvo examen neurológico sin focalidad y TADI con edades de desarrollo muy descendidas. En Grupo 1 se diagnosticó un paciente con una microdeleción 16p11.2 y en Grupo 3 se diagnosticó una duplicación del gen IQSEC2, en un paciente epiléptico de difícil manejo.Conclusiones: Las características fenotípicas permiten orientar la elección de estudios genéticos específicos en niños y adolescentes con DI de etiología previamente indeterminada para acercarse al diagnóstico etiológico.

Existe evidencia de que la terapia robótica (TR) puede mejorar la conducta de niños con Trastorno del Espectro Autista (TEA) de forma espontánea y entretenida. No hay experiencias previas de este tipo de intervenciones en nuestro país.Objetivo: Describir la experiencia clínica del uso de TR y su impacto en las conductas de un grupo de niños con TEA, en un contexto terapéutico.Pacientes y Método: Estudio de tipo experiencia clínica cuasi-experimental. Se seleccionaron 4 niños con diagnóstico clínico de TEA, complementado con ADOS 2 (Escala Observación para Diagnóstico del Autismo); edad 9-13 años y coeficiente intelectual normal con WISC-III (Escala Wechsler Inteligencia para Niños). Aprobado por Comité de Ética Metropolitano Central. Los pacientes asistieron a 10 sesiones estructuradas de terapia robótica, trabajando en duplas de manera colaborativa. Se evaluó la asistencia a talleres, la satisfacción de padres y niños mediante encuestas, la conducta adaptativa con escala de Vineland y la interacción social con pauta de codificación de video.Resultados: Se obtuvo una muy buena adherencia y satisfacción con la actividad. Se evidenció mejoría de conductas de socialización y edad social. La video-codificación mostró un incremento en la interacción social y mejoría en el comportamiento de los pacientes, luego de la asistencia a talleres.Conclusiones: Observamos que la experiencia con TR adaptada al contexto de un centro de salud público chileno fue altamente atractiva y provechosa para pacientes con TEA, mejorando síntomas ejes como son las dificultades en la interacción social y problemas conductuales.

La prevalencia del Trastorno del Espectro Autista (TEA) ha aumentado, variando entre 0,5 y 1% alrededor del mundo. Se desconoce la prevalencia de TEA en Chile.Objetivo: Estimar la prevalencia de Trastorno del Espectro Autista en 2 comunas urbanas de Santiago de Chile.Sujetos y Método: Estudio epidemiológico transversal. Participaron 272 niños entre 18-30 meses que asistían a control sano en dos Centros de Salud Familiar de dos comunas urbanas de la capital. Se utilizó un muestreo consecutivo y se excluyeron los niños que ya estaban siendo controlados por neurología. Se realizó un tamizaje mediante el Cuestionario de Autismo en Niños - Modificado (MCHAT). Los niños con MCHAT alterado fueron evaluados por neuropediatra en el Hospital Clínico San Borja Arriarán y diagnosticados con Trastorno del Espectro Autista de acuerdo a criterio clínico. Se administró la Escala de Observación para el Diagnóstico del Autismo - Segunda Versión (ADOS-2) como complemento diagnóstico. Se estimó la prevalencia de Trastorno del Espectro Autista con intervalo de confianza a 95%.Resultados: 44 niños tuvieron M-CHAT alterado; de ellos 5 fueron diagnosticados clínicamente con Trastorno del Espectro Autista. Se obtuvo una prevalencia de Trastorno del Espectro Autista de 1,95% (IC95% 0,81-4,63), con una distribución por sexo de 4 niños por 1 niña.Conclusiones: Esta es la primera estimación de prevalencia de Trastorno del Espectro Autista en dos comunas de Santiago, Chile. Se obtuvo una alta prevalencia de esta condición, lo que deja en evidencia la necesidad de obtener recursos para el abordaje multidisciplinario precoz de estos pacientes.

Chile as a major international Cu producer faces serious soil contamination issues in mining areas. Currently Chile does not have any specific law governing the maximum permissible concentrations of metals in soils to protect ecosystems and human health. Chile heavily relies on the use of environmental laws of 14 foreign countries; the choice of the country depends on the similarity of its environmental conditions with those in Chile. In this study, we used an online database to compare the similarity of Chilean rocks to those in foreign countries. Likewise, we performed soil sampling and determined the background concentrations of Cu, As, Pb, and Zn in soils of the Aconcagua basin, the largest river basin in the Valparaiso Region of central Chile. The results showed that geochemical patterns in Chile have the greatest resemblance to New Zealand, Mexico, and Italy. The background Cu concentration in the Aconcagua basin (134 mg kg−1) exceeded the legislated limits of New Zealand (100 mg kg−1) and Italy (120 mg kg−1), whereas the background Zn concentration (200 mg kg−1) exceeded the legislated limit of Italy (150 mg kg−1). Due to the elevated natural abundance of Cu and Zn in Chile, international laws should not be applied in Chile for the assessment of soil contamination. In addition, we assessed ecological risk using the results of our previous studies obtained by analyzing native field-contaminated soils of the Valparaiso region. In the Aconcagua basin, Cu posed high risk for plants in 11% of the samples, whereas As posed high risk for earthworms in 48% of the samples. We suggest that future studies are required to search for other organisms that can serve as biomarkers of metal toxicity because our previous studies were limited to plants and earthworms. Importantly, As posed high risk to human health in 25% of the samples in our study. There is a need for future studies to demonstrate empirically an association between soil As and children's blood As in order to establish the national threshold values of soil As to protect human health. We conclude that there is an urgent need in Chile to advance from the current approach of adapting foreign laws to developing Chilean sovereign environmental legislation.

In recent years, Chilean kiwifruit production has been affected by the phytopathogen Pseudomonas syringae pv. actinidiae (Psa), which has caused losses to the industry. In this study, we report the genotypic and phenotypic characterization of 18 Psa isolates obtained from Chilean kiwifruits orchards between 2012 and 2016 from different geographic origins. Genetic analysis by multilocus sequence analysis (MLSA) using four housekeeping genes (gyrB, rpoD, gltA, and gapA) and the identification of type III effector genes suggest that the Chilean Psa isolates belong to the Psa Biovar 3 cluster. All of the isolates were highly homogenous in regard to their phenotypic characteristics. None of the isolates were able to form biofilms over solid plastic surfaces. However, all of the isolates formed cellular aggregates in the air–liquid interface. All of the isolates, except for Psa 889, demonstrated swimming motility, while only isolate Psa 510 demonstrated swarming motility. The biochemical profiles of the isolates revealed differences in 22% of the tests in at least one Psa isolate when analyzed with the BIOLOG system. Interestingly, all of the isolates were able to produce indole using a tryptophan-dependent pathway. PCR analysis revealed the presence of the genes aldA/aldB and iaaL/matE, which are associated with the production of indole-3-acetic acid (IAA) and indole-3-acetyl-3-L-lysine (IAA-Lys), respectively, in P. syringae. In addition, IAA was detected in the cell free supernatant of a representative Chilean Psa strain. This work represents the most extensive analysis in terms of the time and geographic origin of Chilean Psa isolates. To our knowledge, this is the first report of Psa being able to produce IAA. Further studies are needed to determine the potential role of IAA in the virulence of Psa during kiwifruit infections and whether this feature is observed in other Psa biovars.

The export of membrane proteins along the secretory pathway is initiated at the endoplasmic reticulum after proteins are folded and packaged inside this organelle by their recruiting into the coat complex COPII vesicles. It is proposed that cargo receptors are required for the correct transport of proteins to its target membrane, however, little is known about ER export signals for cargo receptors. Erv14/Cornichon belong to a well conserved protein family in Eukaryotes, and have been proposed to function as cargo receptors for many transmembrane proteins. Amino acid sequence alignment showed the presence of a conserved acidic motif in the C-terminal in homologues from plants and yeast. Here, we demonstrate that mutation of the C-terminal acidic motif from ScErv14 or OsCNIH1, did not alter the localization of these cargo receptors, however it modified the proper targeting of the plasma membrane transporters Nha1p, Pdr12p and Qdr2p. Our results suggest that mistargeting of these plasma membrane proteins is a consequence of a weaker interaction between the cargo receptor and cargo proteins caused by the mutation of the C-terminal acidic motif.

Peatlands effectively retain heavy metals and prevent stream and watershed contamination. Sulfate reduction is considered the most significant process of metal immobilization in natural wetlands and microbial sulfate reduction is the presumed mechanism that results in the precipitation of metal sulfides. In this study, we examined the biogeochemical mechanisms involved in zinc retention and accumulation in a metalliferous peatland of western New York. In the reducing conditions of these peatlands zinc sulfides occurred as framboidal aggregates of sphalerite and polytypic wurtzite (2nH, n ⩾ 2) nanocrystallites associated with bacterial cells and organic matter. Bacterial cells were co-located with ZnS inside peat particles where the microenvironment remained anoxic. The peat zinc sulfide was depleted in 34S isotopes relative to the sulfate supplied to the peatland by 18–34 per mill, implicating its biological formation. Extraction of microbial community DNA from peat samples yielded diverse PCR amplicons from dissimilatory sulfite reductase (dsrAB) genes, indicating varied bacterial taxa capable of reducing forms of oxidized sulfur. Nanocrystals with distinct structural features were observed in samples containing contrasting dsrAB sequences. The results of this investigation provide clear evidence that microorganisms can influence the chemical forms of heavy metals in peatland environments. Our findings also provide insight into the conditions necessary to promote the immobilization of chalcophile elements in engineered systems for the treatment of acid mine drainage and wastewater effluents.

Spatial relationships between concentrations of Cd, Fe, Mn, S, and Zn and bacterial genes for dissimilatory sulfate reduction were studied in soils of the Manning peatland region in western New York. Peat cores were collected within a field exhibiting areas of Zn phytotoxicity, and pH and elemental concentrations were determined with depth. The oxidation states of S were estimated using S-XANES spectroscopy. Soil microbial community DNA was extracted from peat soils for ribosomal RNA intergenic spacer analysis (RISA) of diversity profiles with depth. To assess the presence of sulfate-reducing microorganisms (SRM), DNA extracts were also used as templates for PCR detection of dsrAB genes coding for dissimilatory (bi)-sulfite reductase. Elemental distributions, S redox speciation, and detection of dsrAB genes varied with depth and water content. The pH of peat soils increased with depth. The highest concentrations of Zn, Cd, and S occurred at intermediate depths, whereas Mn concentrations were highest in the topmost peat layers. Iron showed a relatively uniform distribution with depth. Concentrations of redox sensitive elements, S and Mn, but not Fe, seemed to respond to variations in water content and indicated vertical redox stratification in peat cores where topmost peats were typically acidic and oxidizing and deeper peats were typically circumneutral and reducing. Even then, S-XANES analyses showed that surface peats contained >50% of the total S in reduced forms while deep peats contained generally

Most copper bioleaching plants operate with a high concentration of sulfate salts, caused by the continuous addition of sulfuric acid and the recycling of the leaching solution. Since the bacteria involved in bioleaching have been generally isolated at low sulfate concentrations, the bacterial population present in the high-sulfate (150 g l −1 ) leaching solution, employed in a copper production plant, was investigated. The iron-oxidizing bacteria able to grow in the leaching solution were enriched by several batch cultivations and, after serial dilution, an abundant bacterial strain was isolated. This strain, called LA, exhibited a relatively constant rate of iron-oxidation in media containing sulfate ions at concentrations ranging from 10 to 150 g l −1 . Culture collection strains of Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans showed limited abilities to grow at sulfate ion concentrations higher than 70 g l −1 . In spite of its tolerance to high sulfate concentrations, strain LA was as sensitive to NaCl as A. ferrooxidans . Comparative sequence analysis of the 16S rRNA gene of strain LA indicated that it is phylogenetically related to strains described as Leptospirillum ferrooxidans . Bacterial community DNA restriction patterns of 16S rRNA genes suggested that strain LA was a minor component of the bacterial population present in leaching solution, but is abundant in ore leached with this solution.

Introduction Heavy Metals in Contaminated Soils: A Review of Sources, Chemistry, Risks and Best Available Strategies for Remediation, Raymond A. Wuana and Felix E. Okieimen Heavy Metal Contamination Leaching Behavior of Heavy Metals and Transformation of Their Speciation in Polluted Soil Receiving Simulated Acid Rain, Shun-an Zheng, Xiangqun Zheng, and Chun Chen Spatially Explicit Analysis of Metal Transfer to Biota: Influence of Soil Contamination and Landscape, Clementine Fritsch, Michael Coeurdassier, Patrick Giraudoux, Francis Raoul, Francis Douay, Dominique Rieffel, Annette de Vaufleury, and Renaud Scheifler Heavy Metal Contamination of Soil and Sediment in Zambia, Yoshinori Ikenaka, Shouta M. M. Nakayama, Kaampwe Muzandu, Kennedy Choongo, Hiroki Teraoka, Naoharu Mizuno, and Mayumi Ishizuka Human Exposure Pathways of Heavy Metals in a Lead-Zinc Mining Area, Jiangsu Province, China, Chang-Sheng Qu, Zong-Wei Ma, Jin Yang, Yang Liu, Jun Bi, and Lei Huang Analysis and Assessment of Heavy Metal Contamination Integrated Assessment of Heavy Metal Contamination in Sediments from a Coastal Industrial Basin, NE China, Xiaoyu Li, Lijuan Liu, Yugang Wang, Geping Luo, Xi Chen, Xiaoliang Yang, Bin Gao, and Xingyuan He A Determination of Metallothionein in Larvae of Freshwater Midges (Chironomus riparius) Using Brdicka Reaction, Ivo Fabrik, Zuzana Ruferova, Klara Hilscherova, Vojtech Adam, Libuse Trnkova, and Rene Kizek Multivariate Statistical Assessment of Heavy Metal Pollution Sources of Groundwater Around a Lead and Zinc Plant, Abbas Ali Zamani, Mohammad Reza Yaftian, and Abdolhossein Parizanganeh Assessment of Heavy Metal Contamination of Agricultural Soil around Dhaka Export Processing Zone (DEPZ), Bangladesh: Implication of Seasonal Variation and Indices, Syed Hafizur Rahman, Dilara Khanam, Tanveer Mehedi Adyel, Mohammad Shahidul Islam, Mohammad Aminul Ahsan, and Mohammad Ahedul Akbor Remediation of Heavy Metal Contamination Phytoremediation of Heavy Metals: A Green Technology, P. Ahmadpour, F. Ahmadpour, T. M. M. Mahmud, Arifin Abdu, M. Soleimani, and F. Hosseini Tayefeh Assessment of the Efficacy of Chelate-Assisted Phytoextraction of Lead by Coffeeweed (Sesbania exaltata Raf.), Gloria Miller, Gregorio Begonia, Maria Begonia, Jennifer Ntoni, and Oscar Hundley Sustainable Sources of Biomass for Bioremediation of Heavy Metals in Waste Water Derived from Coal-Fired Power Generation, Richard J. Saunders, Nicholas A. Paul, Yi Hu, and Rocky de Nys Characterization of the Metabolically Modified Heavy Metal-Resistant Cupriavidus metallidurans Strain MSR33 Generated for Mercury Bioremediation, Luis A. Rojas, Carolina Yanez, Myriam Gonzalez, Soledad Lobos, Kornelia Smalla, and Michael Seeger A Ferritin from Dendrorhynchus zhejiangensis with Heavy Metals Detoxification Activity, Chenghua Li, Zhen Li, Ye Li, Jun Zhou, Chundan Zhang, Xiurong Su, and Taiwu Li Index

Background Copper mining has led to Cu pollution in agricultural soils. In this report, the effects of Cu pollution on bacterial communities of agricultural soils from Valparaiso region, central Chile, were studied. Denaturing gradient gel electrophoresis (DGGE) of the 16S rRNA genes was used for the characterization of bacterial communities from Cu-polluted and non-polluted soils. Cu-resistant bacterial strains were isolated from Cu-polluted soils and characterized. Results DGGE showed a similar high number of bands and banding pattern of the bacterial communities from Cu-polluted and non-polluted soils. The presence of copA genes encoding the multi-copper oxidase that confers Cu-resistance in bacteria was detected by PCR in metagenomic DNA from the three Cu-polluted soils, but not in the non-polluted soil. The number of Cu-tolerant heterotrophic cultivable bacteria was significantly higher in Cu-polluted soils than in the non-polluted soil. Ninety two Cu-resistant bacterial strains were isolated from three Cu-polluted agricultural soils. Five isolated strains showed high resistance to copper (MIC ranged from 3.1 to 4.7 mM) and also resistance to other heavy metals. 16S rRNA gene sequence analyses indicate that these isolates belong to the genera Sphingomonas, Stenotrophomonas and Arthrobacter. The Sphingomonas sp. strains O12, A32 and A55 and Stenotrophomonas sp. C21 possess plasmids containing the Cu-resistance copA genes. Arthrobacter sp. O4 possesses the copA gene, but plasmids were not detected in this strain. The amino acid sequences of CopA from Sphingomonas isolates (O12, A32 and A55), Stenotrophomonas strain (C21) and Arthrobacter strain (O4) are closely related to CopA from Sphingomonas, Stenotrophomonas and Arthrobacter strains, respectively. Conclusions This study suggests that bacterial communities of agricultural soils from central Chile exposed to long-term Cu-pollution have been adapted by acquiring Cu genetic determinants. Five bacterial isolates showed high copper resistance and additional resistance to other heavy metals. Detection of copA gene in plasmids of four Cu-resistant isolates indicates that mobile genetic elements are involved in the spreading of Cu genetic determinants in polluted environments.

The presence of iron, used both as a nutrient and as an electron acceptor, was demonstrated to give an advantage to Escherichia coli bacteria in drinking water. Slight additions of ferrous sulfate to water with initial low iron concentrations led to a significant increase in the number of E. coli bacteria. The presence of ferric oxide in water under anaerobic conditions increased bacterial cultivability.

A washed suspension of the bacteria Escherichia coli, pre-grown on a complex culture medium, was stored in sterilized drinking water for 21 days at 25 degrees C in glass flasks in order to assess the effect of iron corrosion products on the persistenceof the bacteria in drinking water. Four conditions were tested: aerobic with 50 mM lepidocrocite (gamma-FeOOH, an insoluble iron corrosion product), anaerobic with 50 mM lepidocrocite, aerobic without lepidocrocite and anaerobic without lepidocrocite. The survival of E. coli was monitored by their cultivability and their membrane integrity (propidium iodide staining). When the samples were not supplemented with the iron oxide, the cultivability and cell integrity of the bacteria were dramatically altered: from the 10(7) initially added, only 10 CFU ml(-1) remained after 21 days; 90% of the cells exhibited membrane alteration after 2 weeks of storage. In contrast, bacteria with lepidocrocite preserved their cultivability and integrity over the 21 days of storage. In the presence of di-oxygen and without iron oxide, the alteration of cell cultivability was more pronounced than that in anaerobic conditions, suggesting that oxidative stress was part of the phenomenon. When the cells were pre-grown in a growth medium supplemented by a large excess of an easily available form of iron (ferric-citrate), the cells stored a higher amount of iron and persisted one week longer in the iron-free drinking water than cells pre-grown in the standard growth medium. Therefore, in an oligotrophic environment like drinking water, E. coli cells can find the ability to survive a long time through the presence of iron corrosion products. The necessity of controlling the corrosiveness of drinking water for sanitary reasons is therefore emphasized by this study.

BACKGROUND: Mercury-polluted environments are often contaminated with other heavy metals. Therefore, bacteria with resistance to several heavy metals may be useful for bioremediation. Cupriavidus metallidurans CH34 is a model heavy metal-resistant bacterium, but possesses a low resistance to mercury compounds. METHODOLOGY/PRINCIPAL FINDINGS: To improve inorganic and organic mercury resistance of strain CH34, the IncP-1β plasmid pTP6 that provides novel merB, merG genes and additional other mer genes was introduced into the bacterium by biparental mating. The transconjugant Cupriavidus metallidurans strain MSR33 was genetically and biochemically characterized. Strain MSR33 maintained stably the plasmid pTP6 over 70 generations under non-selective conditions. The organomercurial lyase protein MerB and the mercuric reductase MerA of strain MSR33 were synthesized in presence of Hg(2+). The minimum inhibitory concentrations (mM) for strain MSR33 were: Hg(2+), 0.12 and CH(3)Hg(+), 0.08. The addition of Hg(2+) (0.04 mM) at exponential phase had not an effect on the growth rate of strain MSR33. In contrast, after Hg(2+) addition at exponential phase the parental strain CH34 showed an immediate cessation of cell growth. During exposure to Hg(2+) no effects in the morphology of MSR33 cells were observed, whereas CH34 cells exposed to Hg(2+) showed a fuzzy outer membrane. Bioremediation with strain MSR33 of two mercury-contaminated aqueous solutions was evaluated. Hg(2+) (0.10 and 0.15 mM) was completely volatilized by strain MSR33 from the polluted waters in presence of thioglycolate (5 mM) after 2 h. CONCLUSIONS/SIGNIFICANCE: A broad-spectrum mercury-resistant strain MSR33 was generated by incorporation of plasmid pTP6 that was directly isolated from the environment into C. metallidurans CH34. Strain MSR33 is capable to remove mercury from polluted waters. This is the first study to use an IncP-1β plasmid directly isolated from the environment, to generate a novel and stable bacterial strain useful for mercury bioremediation.

Microbiological bioassays of nitrification and nitrogen mineralization have been used for evaluation of soil quality on metal-contaminated soils. We evaluated the effectiveness of nitrification and nitrogen mineralization bioassays as quality indicators of soil degradation caused by metal contamination. We performed standard tests based on protocols of ISO 14238 (2012) and ISO 15685 (2012) on 90 soil samples collected from agricultural areas in central Chile that were historically contaminated by mining activities. Potential nitrification rate (PNR) was best explained by pH and organic matter content (OM) (R²=0.32), while nitrogen mineralization (Nmin) was best explained by OM and clay content (R²=0.44). Following normalization of the bioassays responses with respect to OM yielded significant correlations between PNR and pH and total Cu content (R²=0.22), and between Nmin and clay and total Cu contents (R²=0.19). However, inasmuch as total Cu content improved the regression model showing the inhibitory effect of Cu in both bioassays, it accounted for a mere small proportion of the variance. This was despite the wide range of Cu contents in the soils studied (51-2878 mg kg-1). Hence, due to the known sensitivity of the nitrification and nitrogen mineralization process to physicochemical characteristics of soils, these bioassays seem to have limited applicability for metal toxicity assessment in metal-contaminated soils.