Redescription of the enigmatic myriapod Hanseniellachilensis (Hansen, 1903) (Symphyla, Scutigerellidae) based on scanning electron microscope images of Chilean specimens.

Hanseniellachilensis is the only myriapod of the class Symphyla known from Chile. This garden centipede, or pseudocentipede, was described more than 120 years ago based on morphologically incomplete specimens collected in central Chile, a well-known biodiversity hotspot. In this study, we redescribe this species based on morphologically complete specimens collected near the type locality using scanning electron microscope images. Our study provides the description of diagnostic characters hitherto unknown in this species such as macrochaetae of the tergites and spinnerets of the cerci. We also include a new record from central Chile and discuss the presumed presence of this species in Argentina and Madagascar.

Checklist, diversity and biogeography of ciliates (Ciliophora) from Chile.

There is a significant gap in research and knowledge on the diversity and distribution of Chilean ciliates. To tackle these issues, we used cultures and protargol preparations to describe the ciliates present in poorly explored areas. At these sites, we identified 45 ciliate morphospecies, 35 of which represent unprecedent records to Chile. Then, we brought together our records with literature data to construct a species checklist. This checklist summarises 132 years of data and describes the identity, habitat and distribution of 207 species, including 15 species potentially endemic to Chile. This checklist is far from complete: a diversity estimate suggests that at least two-thirds of the ciliate species occurring in Chile have yet to be described. The checklist is dominated by freshwater taxa because ciliates from marine, brackish and terrestrial environments have rarely been investigated in Chile. Finally, after controlling for sampling artefacts, we found that ciliates exhibit a bell-shaped latitudinal diversity gradient in Chile. This peculiar biogeographical pattern is common in Chile. Plants, animals and testate amoebae also exhibit a bell-shaped latitudinal diversity gradient in Chile. This finding suggests that the historical contingencies that drove the biogeography of the Chilean biota also shaped ciliate biogeography.

Influence of kelp forests on flow around headlands.

Kelp forests affect coastal circulation but their influence on upwelling around headlands is poorly understood. Tidal-cycle surveys off two headlands with contrasting kelp coverage illustrated the influence of kelp forests on headland upwelling. Underway acoustic Doppler current and backscatter profiles were collected simultaneously to surface water temperature. Surveys occurred along three off-headland transects in July 25-29, 2018, off Isla Natividad, located midway on the western coast of the Baja California peninsula. Flows and water temperature distributions off the headland with no kelp coverage were consistent with headland upwelling. In contrast, the kelp around the headland with dense coverage: 1) attenuated the ambient flow; 2) favored an increase in effective radius of flow curvature; 3) promoted flow ducting, which consists of enhancing flow through channels unobstructed by kelp; and 4) suppressed headland upwelling. Kelp suppressed upwelling by channeling the flow away from the headland, keeping nearshore waters warmer than offshore. PLAIN LANGUAGE ABSTRACT: This study documents a way in which biology can affect physics in coastal ocean environments. In particular, the study describes how a kelp forest suppresses the upward pumping of cool subsurface waters that is typically found around headlands. Such suppression of subsurface waters injection occurs via a process that we refer to as 'flow ducting.' In flow ducting, coastal flows are channelized through kelp gaps, concentrated in bands <30 m wide, and kept away from the morphological influences of a headland. This ducting is analogous to the tortuous flow through porous media.

Niche Conservatism Drives the Elevational Diversity Gradient in Major Groups of Free-Living Soil Unicellular Eukaryotes.

Ancestral adaptations to tropical-like climates drive most multicellular biogeography and macroecology. Observational studies suggest that this niche conservatism could also be shaping unicellular biogeography and macroecology, although evidence is limited to Acidobacteria and testate amoebae. We tracked the phylogenetic signal of this niche conservatism in far related and functionally contrasted groups of common soil protists (Bacillariophyta, Cercomonadida, Ciliophora, Euglyphida and Kinetoplastida) along a humid but increasingly cold elevational gradient in Switzerland. Protist diversity decreased, and the size of the geographic ranges of taxa increased with elevation and associated decreasing temperature (climate), which is consistent with a macroecological pattern known as the Rapoport effect. Bacillariophyta exhibited phylogenetically overdispersed communities assembled by competitive exclusion of closely related taxa with shared (conserved) niches. By contrast, Cercomonadida, Ciliophora, Euglyphida and Kinetoplastida exhibited phylogenetically clustered communities assembled by habitat filtering, revealing the coexistence of closely related taxa with shared (conserved) adaptations to cope with the humid but temperate to cold climate of the study site. Phylobetadiversity revealed that soil protists exhibit a strong phylogenetic turnover among elevational sites, suggesting that most taxa have evolutionary constraints that prevent them from colonizing the colder and higher sites of the elevation gradient. Our results suggest that evolutionary constraints determine how soil protists colonize climates departing from warm and humid conditions. We posit that these evolutionary constraints are linked to an ancestral adaptation to tropical-like climates, which limits their survival in exceedingly cold sites. This niche conservatism possibly drives their biogeography and macroecology along latitudinal and altitudinal climatic gradients.

Macronuclear Plasticity in Two South American Populations of Spirostomum (Ciliophora, Heterotrichea) Warns About its Use for Species Classification: Revision and New Insights.

Spirostomum is a widely distributed heterotrichean genus composed of well-known species with described ecology and phylogenetic affinities. The morphological classification of Spirostomum species is mostly based on the body size/shape, number of cortical granule rows and macronuclear characteristics. These features along with molecular phylogenies based on ribosomal genes divide the genus into two phylogroups, one including species with a compact macronucleus, and another including species with a moniliform macronucleus. Here, we present our observations on atypical Spirostomum specimens with unusually two distinct macronuclei and shortened adoral zone of membranelles. These atypical forms appeared in the cultures of S. minus and S. yagiui, sampled at different sites in South America (Chile and Brazil) and associated with unrelated substrate types. Morphological observations of living and stained cells, 18S rRNA gene analyses, and a thorough investigation of the literature suggest that the atypical phenotype may be a result of uncommon pathways during the conjugative process. Thus, we demonstrate that studies of ciliate natural populations and their morphological variations, especially from undersampled biogeographical regions, can reveal the boundaries of widely used morphological characters for Spirostomum taxonomy and species identification.

Ambiente Y COVID-19 EN Argentina / Environment and COVID-19 IN Argentina

INTRODUCCIÓN Si bien en Argentina la emergencia y expansión del COVID-19 tuvo lugar especialmente en los centros urbanos en virtud de la densidad poblacional, otras regiones también se han visto afectadas. Los sectores sociales más vulnerables en ámbitos urbanos y rurales, con históricas dificultades de acceso a servicios básicos de infraestructura y sistemas de salud, se han visto doblemente afectados. OBJETIVOS Analizar los impactos diferenciales de la pandemia por COVID-19 durante el período 2020-2022, considerando las transformaciones territoriales recientes, los problemas ambientales e hídricos y las experiencias de salud comunitaria en escenarios regionales específicos como la región chaqueña y el Área Metropolitana de Buenos Aires (AMBA). Método Diseño cualitativo que triangula fuentes primarias y secundarias con el desarrollo de estudios de caso en Selva (Santiago del Estero), Santa Victoria Este (Salta) y barrios populares de CABA y José C. Paz (AMBA). Resultados Las transformaciones territoriales en ambas regiones han configurado escenarios de desigualdad social, ambiental e hídrica. La distribución de la cobertura de agua y saneamiento en ambos casos margina a poblaciones rurales y barrios populares urbanos del acceso al servicio, lo que trae aparejado el uso de fuentes alternativas con problemas de calidad asociados a contaminantes naturales y/o antrópicos. Las medidas de aislamiento y cuidado dispuestas evidenciaron las consecuencias sanitarias y no sanitarias de la pandemia, en especial en poblaciones con dificultades históricas en el acceso a la salud. La investigación logró relevar procesos organizativos a nivel comunitario frente a la emergencia sanitaria y el modo en que ésta profundizó situaciones críticas preexistentes. Asimismo, y de modo paradójico, en algunas localidades las medidas de aislamiento, junto con otros dispositivos de control, socavaron experiencias comunitarias previas. DISCUSIÓN Es necesario plantear abordajes sanitarios que sean adecuados a los diversos contextos regionales y sociales y que logren revertir lógicas históricas de marginalidad. Para ello se torna central que las políticas sanitarias incorporen la participación de las comunidades locales y reconozcan las determinaciones territoriales de la salud que generan inequidad social.

La musicoterapia como alternativa para el control de la agitación y sedación de pacientes con ventilación mecánica invasiva / Music therapy as an alternative to control psychomotor agitation and sedation of the patients with invasive mechanical ventilation

RESUMEN * Introducción: Se promueve la utilización de la musicoterapia para el manejo de determinados problemas de salud. Objetivo: Precisar el efecto de la musicoterapia sobre la sedación de pacientes con ventilación mecánica invasiva en la Unidad de Cuidados Intensivos del Hospital General Docente "Dr. Agostinho Neto" de Guantánamo en 2018. Método: Durante enero-diciembre de 2018, se realizó un preexperimento con la aplicación de musicoterapia. Participaron 40 pacientes durante el proceso de destete de la ventilación mecánica invasiva. Aleatoriamente, se asignaron a un grupo estudio (n=20) que se les ofreció musicoterapia y a un grupo control (n=20) que no se les ofreció esta terapéutica. Se estudiaron las modificaciones de la frecuencia cardiaca, frecuencia respiratoria, presión arterial media, dosis de sedantes y el nivel de agitación, criterios de profesionales y pacientes respecto a esta técnica. Los datos se resumieron mediante frecuencias absolutas, porcentajes, media y la desviación típica y las diferencias se evaluaron con la técnica t de Students. Resultados: La musicoterapia mejoró la presión arterial media, frecuencia cardiaca y respiratoria, disminuyó las dosis utilizadas de sedantes y mejoró la agitación en el grupo estudio (p<0,05). Los profesionales y pacientes ofrecieron criterios favorables respecto a sus bondades para el control de la agitación (p<0,05). Conclusiones: La musicoterapia es una terapia no farmacológica útil para el control de la agitación del paciente durante el proceso de destete de la ventilación mecánica invasiva.

ABSTRACT * Introduction: Music therapy is promoted as a tool to handle certain health issues. Objective: To specify the effect of music therapy in sedated patients with invasive mechanical ventilation in the intensive care unit at the General Teaching Hospital ¨Dr. Agostinho Neto¨ in Guantanamo during the year 2018. Method: From January to December, 2018, a pre-experimental application of music therapy was undertaken. 40 patients were part of the experiment, during the process of weaning from invasive mechanical ventilation. Patients were randomly selected to the studied group (n=20) or to a control group (n=20), the first being treated with music therapy while the last was not. Modifications in heart rate, respiratory rate, mean arterial pressure, sedative dose and levels of psychomotor agitation were taken into account; also listening to professionals´ and patients´ opinions on the treatment. The information gathered was sorted in absolute frequencies, percentages, mean and standard deviation, and the differences were evaluated with Student´s t-distribution. Results: Music therapy improved heart and respiratory rate, mean arterial pressure and helped to decrease the use of sedative doses; besides, it improved the agitation in the group studied (p<0.05). Patients and professionals both gave favorable opinions about the treatment and its ability to control the agitation (p<0.05). Conclusions: Music therapy constitutes a non-pharmacological form of therapy that proves effective to control agitation in patients during the process of weaning from invasive mechanical ventilation.

Morbilidad y mortalidad por disfunción renal aguda en la unidad de terapia intensiva del Hospital General Docente Dr. Agostinho Neto / Morbidity and mortality for acute kidney failure in the intensive care unit of the General Teaching Hospital ¨Dr. Agostinho Neto¨

RESUMEN Introducción: En el Hospital General Docente "Dr. Agostinho Neto", de Guantánamo, no se ha caracterizado la problemática del daño renal agudo en la unidad de terapia intensiva. Objetivo: caracterizar esta afección en pacientes ingresados en la citada unidad en el periodo 2018-2019. Método: Se realizó un estudio descriptivo, retrospectivo y longitudinal, aprobado por el comité de ética. El universo de estudio se constituyó por el total de pacientes con este diagnóstico según la clasificación Acute Kidney Injury Network (AKIN). Se estudiaron las características de los pacientes (edad, sexo, comorbilidad, etiología, estadía en la unidad de terapia intensiva, necesidad de hemodiálisis, estado al egreso) y del daño renal agudo (estadio según los criterios de la escala AKIN). Resultados: En el 35,6 % de los pacientes se diagnosticó esta enfermedad, sobre todo en hombres (56,7 %) y con edad de 66,3 ± 24,3 años. El 41,4 % padeció hipertensión arterial sistémica. En el 48,9 % la enfermedad se presentó un en estadio 1, y en el 69,4 % la sepsis fue la principal causa. La mortalidad al egreso hospitalario fue de 16,4 %, y a los 30 días fue de 25,4 %. Se realizó hemodiálisis al 13,8 % de los pacientes, en los que el riesgo de muerte fue superior. Conclusiones: En la unidad de terapia intensiva es elevada la proporción de pacientes con daño renal agudo y resulta útil la escala que se utilizó para el diagnóstico y la evaluación de la gravedad y el pronóstico de los pacientes afectados.

ABSTRACT Introduction: Acute kidney injury in the intensive care unit in the General Teaching Hospital ¨Dr. Agostinho Neto¨ in Guantanamo has not been characterized. Objective: To characterize this disease in patients in the intensive care unit in the mentioned institution in the period 2018-2019. Method: A descriptive, retrospective and longitudinal study was undertaken, all approved by the ethics committee. The study population was made out of the total amount of the patients diagnosed according to the classification of the Acute Kidney Injury Network (AKIN). The variables taken into account were: age, gender, comorbidity, etiology, time in the intensive care unit, requirement for hemodialysis and status of the patient at the time of discharge, plus the stages of the acute kidney injury according to the AKIN scale. Results: Acute kidney injury was diagnosed in the 35.6% of the patients, especially in male patients (56.7%) with ages between 66.3 ± 24.3 years. 41.4% of the patients suffered of systemic arterial hypertension. Stage 1 was found in the 48.9% of the cases, and sepsis was the main cause in 69.4%. Mortality at the time of discharge represented the 16.4%; and after the following 30 days went up to 25.4%. Hemodialysis was required in the 13.8% of the patients; in wich the risk of death was significatively higher. Conclusions: There is a high number of patients with acute kidney injury in the intensive care unit, and it was really useful the scale implemented for diagnosis and evaluation of the severity of the condition and the prognosis of the patients.

Daño renal agudo en pacientes con ventilación mecánica invasiva, Guantánamo 2018-2019 / Acute kidney injury in patients with invasive mechanical ventilation in Guantanamo, 2018-2019

RESUMEN Introducción: El daño renal agudo es una complicación frecuente en las Unidades de Terapia Intensiva, sobre todo en pacientes con ventilación mecánica. Objetivo: Caracterizar el daño renal agudo en los pacientes tratados con ventilación mecánica invasiva en la Unidad de Terapia Intensiva del Hospital General Docente "Dr. Agostinho Neto" durante el periodo 2108-2019. Método: Se realizó un estudio descriptivo, retrospectivo y longitudinal, que se aprobó por el Comité de Ética. El universo de estudio se constituyó por el total de pacientes con este diagnóstico según la clasificación Acute Kidney Injury Network (AKIN). Se estudiaron las características de los pacientes (necesidad y duración de la VAM, necesidad de hemodiálisis, estado al egreso) y del daño renal agudo (estadio y etiología). Resultados: El 47,5 % de los pacientes tratados con este soporte vital presentó un daño renal agudo, sobre todo los que la demandaron por siete o más días (68,4 %). El riesgo de muerte fue superior en los pacientes que requirieron ventilación mecánica o hemodiálisis. En los pacientes con daño renal estadio 2 y 3 de la clasificación que se utilizó presentaron un riesgo tres veces o más superior comparado con los que no necesitaron estas terapias. La sepsis (69,4 %) fue la principal causa del daño renal agudo. Conclusiones: El uso de ventilación mecánica invasiva y la presentación de un daño renal agudo son condiciones con una fuerte asociación, juntas y separadas se correlacionan con la mortalidad.

ABSTRACT Introduction: Acute kidney injury is a very common complication in the intensive care units, especially in patients with invasive mechanical ventilation. Objective: To characterize acute kidney damage in patients with invasive mechanical ventilation in the intensive care unit at the General Teaching Hospital ¨Dr. Agostinho Neto¨ within the period 2018-2019. Method: A descriptive, retrospective and longitudinal study approved by the Ethics Committee was carried out. The study population was constituted by the total of patients with the diagnosis, according to the Acute Kidney Injury Network (AKIN). Characteristics and variables like: reason for the invasive mechanical ventilation, its duration, hemodialysis, and status of the patient at time of discharge were taken into account, along with the characteristics of the kidney injury (stages and etiology). Results: 47.5 % of the patients treated with life support showed acute kidney injury, especially the ones with more than a week of mechanical ventilation (68.4 %). The risk of death was higher in the patients with mechanical ventilation and hemodialysis. In the patients with stage 2 and 3 of the scale used for kidney injury presented 3 times more risk compared to those who did not require these treatments. Sepsis was the main cause of acute kidney injury (69.4 %). Conclusions: the use of invasive mechanical ventilation and acute kidney injury are deeply related to each other, both of them constitute main issues in the variables of mortality.

Dispersal limitations and historical factors determine the biogeography of specialized terrestrial protists.

Recent studies show that soil eukaryotic diversity is immense and dominated by micro-organisms. However, it is unclear to what extent the processes that shape the distribution of diversity in plants and animals also apply to micro-organisms. Major diversification events in multicellular organisms have often been attributed to long-term climatic and geological processes, but the impact of such processes on protist diversity has received much less attention as their distribution has often been believed to be largely cosmopolitan. Here, we quantified phylogeographical patterns in Hyalosphenia papilio, a large testate amoeba restricted to Holarctic Sphagnum-dominated peatlands, to test if the current distribution of its genetic diversity can be explained by historical factors or by the current distribution of suitable habitats. Phylogenetic diversity was higher in Western North America, corresponding to the inferred geographical origin of the H. papilio complex, and was lower in Eurasia despite extensive suitable habitats. These results suggest that patterns of phylogenetic diversity and distribution can be explained by the history of Holarctic Sphagnum peatland range expansions and contractions in response to Quaternary glaciations that promoted cladogenetic range evolution, rather than the contemporary distribution of suitable habitats. Species distributions were positively correlated with climatic niche breadth, suggesting that climatic tolerance is key to dispersal ability in H. papilio. This implies that, at least for large and specialized terrestrial micro-organisms, propagule dispersal is slow enough that historical processes may contribute to their diversification and phylogeographical patterns and may partly explain their very high overall diversity.

Diagnóstico e intervención médica en la debilidad muscular adquirida / Diagnóstico e intervenção médica na fraqueza muscular adquirida / Diagnosis and medical intervention in acquired muscle weakness

Introducción: la debilidad adquirida del paciente en la Unidad de Terapia Intensiva es un problema que le provoca deficiencias en su estado físico y funcional. Objetivo: sistematizar contenidos esenciales relacionados con la debilidad adquirida del paciente en la Unidad de Terapia Intensiva. Método: en el Hospital General Docente Dr. Agostinho Neto, entre enero y septiembre de 2019 se hizo una revisión narrativa sobre el tema a través de una búsqueda en bases de datos electrónicas (Biblioteca Virtual en Salud, LILACS, PubMed, SciELO, RedALyC, Scopus). Se localizaron 135 documentos y se eligieron 25 relevantes para el objetivo de la revisión. La información se estructuró en los siguientes aspectos sobre la debilidad adquirida del paciente en la Unidad de Terapia Intensiva: definición, antecedentes históricos, epidemiología, fisiopatología, diagnóstico e intervención médica. Resultados: se identificaron controversias sobre los criterios diagnósticos precisos, el protocolo de actuación para su prevención y rehabilitación y la carencia de un instrumento para estratificar el riesgo de esta complicación. Conclusiones: se sistematizaron las bases para la preparación de los profesionales en el diagnóstico, la prevención de la debilidad adquirida del paciente en la Unidad de Terapia Intensiva y su rehabilitación(AU)

Introduction: the patient's acquired weakness in the Intensive Care Unit is a problem that causes deficiencies in his physical and functional state. Objective: systematize essential contents related to the patient's acquired weakness in the Intensive Care Unit. Method: in the General Teaching Hospital "Dr. Agostinho Neto", between January and September 2019, a narrative review of the subject was made through a search in electronic databases (Virtual Health Library, LILACS, PubMed, SciELO, RedALyC, Scopus). 135 documents were located and 25 relevant for the purpose of the review were chosen. The information was structured in the following aspects about the patient's acquired weakness in the Intensive Care Unit: definition, historical background, epidemiology, pathophysiology, diagnosis and medical intervention. Results: controversies were identified about the precise diagnostic criteria, the protocol of action for its prevention and rehabilitation and the lack of an instrument to stratify the risk of this complication. Conclusions: the bases for the preparation of the professionals in the diagnosis, the prevention of the acquired weakness of the patient in the Intensive Care Unit and its rehabilitation were systematized(AU)

Introdução: a fragilidade adquirida pelo paciente na Unidade de Terapia Intensiva é um problema que causa deficiências no seu estado físico e funcional. Objetivo: sistematizar conteúdos essenciais relacionados à fraqueza adquirida do paciente na Unidade de Terapia Intensiva. Método: no Hospital Geral de Ensino "Dr. Agostinho Neto", entre janeiro e setembro de 2019, foi realizada uma revisão narrativa do assunto através de uma busca em bases de dados eletrônicas (Biblioteca Virtual em Saúde, LILACS, PubMed, SciELO, RedALyC, Scopus). Foram localizados 135 documentos e escolhidos 25 relevantes para a finalidade da revisão. As informações foram estruturadas nos seguintes aspectos sobre a fragilidade adquirida pelo paciente na Unidade de Terapia Intensiva: definição, histórico, epidemiologia, fisiopatologia, diagnóstico e intervenção médica. Resultados: foram identificadas controvérsias sobre os critérios diagnósticos precisos, o protocolo de ação para sua prevenção e reabilitação e a falta de um instrumento para estratificar o risco dessa complicação. Conclusões: foram sistematizadas as bases para o preparo dos profissionais no diagnóstico, a prevenção da fragilidade adquirida do paciente na Unidade de Terapia Intensiva e sua reabilitação(AU)

Genetic Diversity and Distribution of Blastocystis Subtype 3 in Human Populations, with Special Reference to a Rural Population in Central Mexico.

Blastocystis subtype 3 (ST3) is a parasitic protist found in the digestive tract of symptomatic and asymptomatic humans around the world. While this parasite exhibits a high prevalence in the human population, its true geographic distribution and global genetic diversity are still unknown. This gap in knowledge limits the understanding of the spread mechanisms, epidemiology, and impact that this parasite has on human populations. Herein, we provided new data on the geographical distribution and genetic diversity of Blastocystis ST3 from a rural human population in Mexico. To do so, we collected and targeted the SSU-rDNA region in fecal samples from this population and further compared its genetic diversity and structure with that previously observed in populations of Blastocystis ST3 from other regions of the planet. Our analyses reveled that diversity of Blastocystis ST3 showed a high haplotype diversity and genetic structure to the world level; however, they were low in the Morelos population. The haplotype network revealed a common widespread haplotype from which the others were generated recently. Finally, our results suggested a recent expansion of the diversity of Blastocystis ST3 worldwide.

Soil protists: a fertile frontier in soil biology research.

Protists include all eukaryotes except plants, fungi and animals. They are an essential, yet often forgotten, component of the soil microbiome. Method developments have now furthered our understanding of the real taxonomic and functional diversity of soil protists. They occupy key roles in microbial foodwebs as consumers of bacteria, fungi and other small eukaryotes. As parasites of plants, animals and even of larger protists, they regulate populations and shape communities. Pathogenic forms play a major role in public health issues as human parasites, or act as agricultural pests. Predatory soil protists release nutrients enhancing plant growth. Soil protists are of key importance for our understanding of eukaryotic evolution and microbial biogeography. Soil protists are also useful in applied research as bioindicators of soil quality, as models in ecotoxicology and as potential biofertilizers and biocontrol agents. In this review, we provide an overview of the enormous morphological, taxonomical and functional diversity of soil protists, and discuss current challenges and opportunities in soil protistology. Research in soil biology would clearly benefit from incorporating more protistology alongside the study of bacteria, fungi and animals.

Environmental filtering and phylogenetic clustering correlate with the distribution patterns of cryptic protist species.

The community composition of any group of organisms should theoretically be determined by a combination of assembly processes including resource partitioning, competition, environmental filtering, and phylogenetic legacy. Environmental DNA studies have revealed a huge diversity of protists in all environments, raising questions about the ecological significance of such diversity and the degree to which they obey to the same rules as macroscopic organisms. The fast-growing cultivable protist species on which hypotheses are usually experimentally tested represent only a minority of the protist diversity. Addressing these questions for the lesser known majority can only be inferred through observational studies. We conducted an environmental DNA survey of the genus Nebela, a group of closely related testate (shelled) amoeba species, in different habitats within Sphagnum-dominated peatlands. Identification based on the mitochondrial cytochrome c oxidase 1 gene, allowed species-level resolution as well as phylogenetic reconstruction. Community composition varied strongly across habitats and associated environmental gradients. Species showed little overlap in their realized niche, suggesting resource partitioning, and a strong influence of environmental filtering driving community composition. Furthermore, phylogenetic clustering was observed in the most nitrogen-poor samples, supporting phylogenetic inheritance of adaptations in the group of N. guttata. This study showed that the studied free-living unicellular eukaryotes follow to community assembly rules similar to those known to determine plant and animal communities; the same may be true for much of the huge functional and taxonomic diversity of protists.

Geographical distance and local environmental conditions drive the genetic population structure of a freshwater microalga (Bathycoccaceae; Chlorophyta) in Patagonian lakes.

The patterns and mechanisms underlying the genetic structure of microbial populations remain unresolved. Herein we investigated the role played by two non-mutually exclusive models (i.e. isolation by distance and isolation by environment) in shaping the genetic structure of lacustrine populations of a microalga (a freshwater Bathycoccaceae) in the Argentinean Patagonia. To our knowledge, this was the first study to investigate the genetic population structure in a South American microorganism. Population-level analyses based on ITS1-5.8S-ITS2 sequences revealed high levels of nucleotide and haplotype diversity within and among populations. Fixation index and a spatially explicit Bayesian analysis confirmed the occurrence of genetically distinct microalga populations in Patagonia. Isolation by distance and isolation by environment accounted for 38.5% and 17.7% of the genetic structure observed, respectively, whereas together these models accounted for 41% of the genetic differentiation. While our results highlighted isolation by distance and isolation by environment as important mechanisms in driving the genetic population structure of the microalga studied, none of these models (either alone or together) could explain the entire genetic differentiation observed. The unexplained variation in the genetic differentiation observed could be the result of founder events combined with rapid local adaptations, as proposed by the monopolisation hypothesis.

First freshwater member ever reported for the family Bathycoccaceae (Chlorophyta; Archaeplastida) from Argentinean Patagonia revealed by environmental DNA survey.

We characterized molecularly the first freshwater member ever reported for the family Bathycoccaceae in Lake Musters (Argentinean Patagonia). Members of this family are extremely numerous and play a key ecological role in marine systems as primary producers. We cloned a fragment comprising the SSU rRNA gene+ITS region from environmental DNA using specific mamiellophyte primers. The unique SSU rRNA gene sequence obtained clustered robustly with Bathycoccus prasinos. Analysis of the two-dimensional structure of the ITS region showed the presence of a typical supplementary helix in the ITS-2 region, a synapomorphy of Bathycoccaceae, which confirmed further its phylogenetic placement. We finally discuss the possible causes for the presence of this organism in Lake Musters.

Microbial eukaryote communities exhibit robust biogeographical patterns along a gradient of Patagonian and Antarctic lakes.

Microbial eukaryotes play important roles in aquatic ecosystem functioning. Unravelling their distribution patterns and biogeography provides important baseline information to infer the underlying mechanisms that regulate the biodiversity and complexity of ecosystems. We studied the distribution patterns and factors driving diversity gradients in microeukaryote communities (total, abundant, uncommon and rare community composition) along a latitudinal gradient of lakes distributed from Argentinean Patagonia to Maritime Antarctica using both denaturing gradient gel electrophoresis (DGGE) and high-throughput sequencing (Illumina HiSeq). DGGE and abundant Illumina operational taxonomic units (OTUs) showed both decreasing richness with latitude and significant differences between Patagonian and Antarctic lakes communities. In contrast, total richness did not change significantly across the latitudinal gradient, although evenness and diversity indices were significantly higher in Patagonian lakes. Beta-diversity was characterized by a high species turnover, influenced by both environmental and geographical descriptors, although this pattern faded in the rare community. Our results suggest the co-existence of a 'core biosphere' containing reduced number of abundant/dominant OTUs on which classical ecological rules apply, together with a much larger seedbank of rare OTUs driven by stochastic and reduced dispersal processes. These findings shed new light on the biogeographical patterns and forces structuring inland microeukaryote composition across broad spatial scales.

Cinderella's helping pigeons of the microbial world: The potential of testate amoebae for identifying cryptotephra.

Cryptotephra (particles <125µm) is a key record for monitoring past and current volcanic activity. However, its extraction from the host sediment and analysis is often long and difficult because of its small size. Finding a simple method to extract cryptotephra from environmental samples would therefore make its analysis much easier. We hypothesized that arcellinid testate amoebae may hold such a potential. These free-living shelled protists are among the earliest microorganisms to colonize volcanic tephra, and build their shell by agglutinating minerals from their environment. We analyzed by X-ray Spectrometry the mineral signature of tephra from the 2011 Puyehue-Cordon Caulle Volcanic Complex (Chile) eruption ash fallout and compared it to that of the shells of 51 individual testate amoebae (three individuals from each of 17 species) from 13 samples collected at different distances from the active vent. The mineral composition of particles within shells closely matched that of similar size class particles from their environment. The capacity of testate amoebae to randomly use mineral grains from their environment makes it possible to use their shells to assess the mineral composition of cryptotephra from soil, peat or sediment samples. Testate amoebae therefore represent the microbial world's version of Cinderella's helping pigeons.

Checklist, diversity and distribution of testate amoebae in Chile.

Bringing together more than 170 years of data, this study represents the first attempt to construct a species checklist and analyze the diversity and distribution of testate amoebae in Chile, a country that encompasses the southwestern region of South America, countless islands and part of the Antarctic. In Chile, known diversity includes 416 testate amoeba taxa (64 genera, 352 infrageneric taxa), 24 of which are here reported for the first time. Species-accumulation plots show that in Chile, the number of testate amoeba species reported has been continually increasing since the mid-19th century without leveling off. Testate amoebae have been recorded in 37 different habitats, though they are more diverse in peatlands and rainforest soils. Only 11% of species are widespread in continental Chile, while the remaining 89% of the species exhibit medium or short latitudinal distribution ranges. Also, species composition of insular Chile and the Chilean Antarctic territory is a depauperated subset of that found in continental Chile. Nearly, the 10% of the species reported here are endemic to Chile and many of them are distributed only within the so-called Chilean biodiversity hotspot (ca. 25° S-47° S). These findings are here thoroughly discussed in a biogeographical and evolutionary context.