Corrigendum: Hyperarid soil microbial community response to simulated rainfall.

[This corrects the article DOI: 10.3389/fmicb.2023.1202266.].

Hyperarid soil microbial community response to simulated rainfall.

The exceptionally long and protracted aridity in the Atacama Desert (AD), Chile, provides an extreme, terrestrial ecosystem that is ideal for studying microbial community dynamics under hyperarid conditions. Our aim was to characterize the temporal response of hyperarid soil AD microbial communities to ex situ simulated rainfall (5% g water/g dry soil for 4 weeks) without nutrient amendment. We conducted replicated microcosm experiments with surface soils from two previously well-characterized AD hyperarid locations near Yungay at 1242 and 1609 masl (YUN1242 and YUN1609) with distinct microbial community compositions and average soil relative humidity levels of 21 and 17%, respectively. The bacterial and archaeal response to soil wetting was evaluated by 16S rRNA gene qPCR, and amplicon sequencing. Initial YUN1242 bacterial and archaeal 16S rRNA gene copy numbers were significantly higher than for YUN1609. Over the next 4 weeks, qPCR results showed significant increases in viable bacterial abundance, whereas archaeal abundance decreased. Both communities were dominated by 10 prokaryotic phyla (Actinobacteriota, Proteobacteria, Chloroflexota, Gemmatimonadota, Firmicutes, Bacteroidota, Planctomycetota, Nitrospirota, Cyanobacteriota, and Crenarchaeota) but there were significant site differences in the relative abundances of Gemmatimonadota and Chloroflexota, and specific actinobacterial orders. The response to simulated rainfall was distinct for the two communities. The actinobacterial taxa in the YUN1242 community showed rapid changes while the same taxa in the YUN1609 community remained relatively stable until day 30. Analysis of inferred function of the YUN1242 microbiome response implied an increase in the relative abundance of known spore-forming taxa with the capacity for mixotrophy at the expense of more oligotrophic taxa, whereas the YUN1609 community retained a stable profile of oligotrophic, facultative chemolithoautotrophic and mixotrophic taxa. These results indicate that bacterial communities in extreme hyperarid soils have the capacity for growth in response to simulated rainfall; however, historic variations in long-term hyperaridity exposure produce communities with distinct putative metabolic capacities.

Physical, chemical, and microbial feedbacks controlling brine geochemistry and lake morphology in polyextreme salar environments.

Despite the harsh environmental conditions in the world's oldest and driest desert, some salt flat or 'salar' environments in the Atacama Desert host standing bodies of water known as saline lakes. Evaporite minerals deposited within saline lakes result from the equilibrium of environmental, sedimentological, and biogeochemical processes that occur in the salar; consequently, these minerals are sensitive records of human activities and ecological, evolutionary, and geological changes. The objective of this study was to evaluate feedbacks between physical, chemical, and microbial processes that culminate in distinct trends in brine chemistry, saline lake morphology, and associated evaporite sediments. Using samples from the Puquios of the Salar de Llamara, Atacama Desert, northern Chile, an analysis of spatial gradients and vertical stratification of lake elemental chemistry and mineral saturation indices were integrated with a comprehensive analysis of lake morphology, including depth, slope gradient, substrate type, and mineralogy. Lake waters ranged from saline to hypersaline, and exhibited normal, well mixed and inverse stratification patterns, and results suggest a correlation with lake morphology in the Salar de Llamara. Saline to hypersaline lakes (>150 mS/cm) with stratified brines tended to have crystalline substrate and deep (>35 cm) and steep-sided lake morphologies, while unstratified lakes with lower electrical conductivity (<90 mS/cm and microbial substrates had gentle slopes and characteristically shallow depths (<30 cm). Differences in minor element chemistry (Mn and Sr) between saline lakes were observed on scales of meters to kilometers, and result in different accessory mineral assemblages. Quantification of the physical, chemical, and microbial feedbacks that produce the observed heterogeneity in these ecosystems provides key insight into the geochemical composition and lake morphology of saline lakes in extreme environments around the world.

Effect of Cathodic Protection on Reinforced Concrete with Fly Ash Using Electrochemical Noise.

Corrosion of steel reinforcement is the major factor that limits the durability and serviceability performance of reinforced concrete structures. Impressed current cathodic protection (ICCP) is a widely used method to protect steel reinforcements against corrosion. This research aimed to study the effect of cathodic protection on reinforced concrete with fly ash using electrochemical noise (EN). Two types of reinforced concrete mixtures were manufactured; 100% Ordinary Portland Cement (OCP) and replacing 15% of cement using fly ash (OCPFA). The specimens were under-designed protected conditions (-1000 ≤ E ≤ -850 mV vs. Ag/AgCl) and cathodic overprotection (E < -1000 mV vs. Ag/AgCl) by impressed current, and specimens concrete were immersed in a 3.5 wt.% sodium chloride (NaCl) Solution. The analysis of electrochemical noise-time series showed that the mixtures microstructure influenced the corrosion process. Transients of uniform corrosion were observed in the specimens elaborated with (OPC), unlike those elaborated with (OPCFA). This phenomenon marked the difference in the concrete matrix's hydration products, preventing Cl- ions flow and showing passive current and potential transients in most specimens.

Clinical and genetic differences between bipolar disorder type 1 and 2 in multiplex families.

The two major subtypes of bipolar disorder (BD), BD-I and BD-II, are distinguished based on the presence of manic or hypomanic episodes. Historically, BD-II was perceived as a less severe form of BD-I. Recent research has challenged this concept of a severity continuum. Studies in large samples of unrelated patients have described clinical and genetic differences between the subtypes. Besides an increased schizophrenia polygenic risk load in BD-I, these studies also observed an increased depression risk load in BD-II patients. The present study assessed whether such clinical and genetic differences are also found in BD patients from multiplex families, which exhibit reduced genetic and environmental heterogeneity. Comparing 252 BD-I and 75 BD-II patients from the Andalusian Bipolar Family (ABiF) study, the clinical course, symptoms during depressive and manic episodes, and psychiatric comorbidities were analyzed. Furthermore, polygenic risk scores (PRS) for BD, schizophrenia, and depression were assessed. BD-I patients not only suffered from more severe symptoms during manic episodes but also more frequently showed incapacity during depressive episodes. A higher BD PRS was significantly associated with suicidal ideation. Moreover, BD-I cases exhibited lower depression PRS. In line with a severity continuum from BD-II to BD-I, our results link BD-I to a more pronounced clinical presentation in both mania and depression and indicate that the polygenic risk load of BD predisposes to more severe disorder characteristics. Nevertheless, our results suggest that the genetic risk burden for depression also shapes disorder presentation and increases the likelihood of BD-II subtype development.

Bipolar multiplex families have an increased burden of common risk variants for psychiatric disorders.

Multiplex families with a high prevalence of a psychiatric disorder are often examined to identify rare genetic variants with large effect sizes. In the present study, we analysed whether the risk for bipolar disorder (BD) in BD multiplex families is influenced by common genetic variants. Furthermore, we investigated whether this risk is conferred mainly by BD-specific risk variants or by variants also associated with the susceptibility to schizophrenia or major depression. In total, 395 individuals from 33 Andalusian BD multiplex families (166 BD, 78 major depressive disorder, 151 unaffected) as well as 438 subjects from an independent, BD case/control cohort (161 unrelated BD, 277 unrelated controls) were analysed. Polygenic risk scores (PRS) for BD, schizophrenia (SCZ), and major depression were calculated and compared between the cohorts. Both the familial BD cases and unaffected family members had higher PRS for all three psychiatric disorders than the independent controls, with BD and SCZ being significant after correction for multiple testing, suggesting a high baseline risk for several psychiatric disorders in the families. Moreover, familial BD cases showed significantly higher BD PRS than unaffected family members and unrelated BD cases. A plausible hypothesis is that, in multiplex families with a general increase in risk for psychiatric disease, BD development is attributable to a high burden of common variants that confer a specific risk for BD. The present analyses demonstrated that common genetic risk variants for psychiatric disorders are likely to contribute to the high incidence of affective psychiatric disorders in the multiplex families. However, the PRS explained only part of the observed phenotypic variance, and rare variants might have also contributed to disease development.

Modeling spatial pattern of dengue in North Central Mexico using survey data and logistic regression.

Dengue is a major public health concern mainly in tropical and subtropical environments worldwide. Despite several attempts to prevent this disease occurring in tropical regions of Mexico, it has not yet been controlled. This work focused on spatial modeling of confirmed dengue fever cases that occurred during the period 2010-2014 in the Huasteca Potosina region of Mexico. Multivariable Logistic Regression Modeling (MLRM) was used to determine the relationship between explanatory variables and the presence/absence of dengue. Model performance was evaluated using the area under curve (AUC) of the relative operating characteristic (ROC); AUC > 0.95. A high spatial resolution map was created to reveal the most probable patterns of dengue risk. Our results can be used for targeted control and prevention programs at local and regional levels. This methodology can be applied to other major diseases that are spatially distributed in accordance with environmental factors.

Knowledge, Attitudes, and Intentions towards HIV Pre-Exposure Prophylaxis among Nursing Students in Spain.

Human immunodeficiency virus (HIV) infection is one of the main causes of morbidity and mortality worldwide. Among the preventive approaches proposed to control this disease is pre-exposure prophylaxis (PrEP), whose effectiveness depends on the medication adherence. The aim of the present study was to determine the knowledge and attitudes about PrEP among a sample of Spanish nursing students as well as their intentions of receiving it in case it was indicated. An observational cross-sectional descriptive study was carried out. A total of 570 nursing students from the University of Santiago de Compostela (Spain), ≥18 years old and of both sexes were invited to self-complete a questionnaire between February and March 2020. A total of 352 students decided to participate in the study. Participants had low knowledge [overall knowledge score 1(0-2)] and a neutral attitude towards PrEP. The intention of receiving PrEP improved significantly after the completion of the questionnaire and the administration of information about PrEP (p = 0.039; before: 23.58% and after: 93.77%). Nursing staff play an important role in the prevention of sexually transmitted diseases, so their training in preventive strategies, such as PrEP, could help to reduce the incidence of new cases of HIV infection.

Whole-exome sequencing of 81 individuals from 27 multiply affected bipolar disorder families.

Bipolar disorder (BD) is a highly heritable neuropsychiatric disease characterized by recurrent episodes of depression and mania. Research suggests that the cumulative impact of common alleles explains 25-38% of phenotypic variance, and that rare variants may contribute to BD susceptibility. To identify rare, high-penetrance susceptibility variants for BD, whole-exome sequencing (WES) was performed in three affected individuals from each of 27 multiply affected families from Spain and Germany. WES identified 378 rare, non-synonymous, and potentially functional variants. These spanned 368 genes, and were carried by all three affected members in at least one family. Eight of the 368 genes harbored rare variants that were implicated in at least two independent families. In an extended segregation analysis involving additional family members, five of these eight genes harbored variants showing full or nearly full cosegregation with BD. These included the brain-expressed genes RGS12 and NCKAP5, which were considered the most promising BD candidates on the basis of independent evidence. Gene enrichment analysis for all 368 genes revealed significant enrichment for four pathways, including genes reported in de novo studies of autism (padj < 0.006) and schizophrenia (padj = 0.015). These results suggest a possible genetic overlap with BD for autism and schizophrenia at the rare-sequence-variant level. The present study implicates novel candidate genes for BD development, and may contribute to an improved understanding of the biological basis of this common and often devastating disease.

Perfil clínico neuropsicológico del deterioro cognitivo subtipo posible Alzheimer / Clinical and Neuropsychological Profile of Possible Alzheimer subtype neurocognitive disorder

Introducción: La enfermedad de Alzheimer se presenta con diferentes fenotipos neuropsicológicos y se considera que el deterioro de la memoria es su afectación más sobresaliente; no obstante, estudios recientes sugieren que los trastornos en las funciones ejecutivas pueden constituir marcadores muy tempranos de la enfermedad. Objetivos: Caracterizar los perfiles clínicos y neuropsicológicos que constituyen marcadores fenotípicos de los trastornos neurocognitivos subtipo posible Alzheimer. Métodos: Se realizó un estudio descriptivo y transversal de 39 enfermos con edades comprendidas entre 57-85 años, clasificados según los criterios del DSM-5, con deterioro cognitivo leve y mayor, catalogados desde el punto de vista etiológico en el subtipo posible Alzheimer. Se evaluaron múltiples dominios cognitivos (atención compleja, memoria y aprendizaje, funciones ejecutivas, lenguaje, funciones motoras y perceptuales) y se hizo una evaluación detallada de las funciones ejecutivas mediante un grupo de test neuropsicológicos específicos. Resultados: El análisis estadístico demostró que entre los dos grupos de estudio con deterioro cognitivo existen diferencias significativas en cuanto al nivel de funcionamiento cognitivo en todos los dominios explorados, excepto en la percepción y funciones motoras. Así mismo, los resultados demostraron que el nivel de rendimiento para cada función evaluada dentro del dominio de las funciones ejecutivas es significativamente diferente entre ambos grupos con deterioro cognitivo, excepto para la orientación espacial. Conclusiones: El perfil neuropsicológico del deterioro cognitivo subtipo posible Alzheimer se caracterizó por una afectación en múltiples dominios, con predominio de la disfunción ejecutiva focalizada en las áreas de la flexibilidad mental e inhibición de automatismos.

Introduction: Alzheimer disease is presented with different neuropsychological phenotypes and it is considered that the memory disorder is its most important one; however, recent studies suggest that the dysfunctions in the executive functions can constitute very early markers of the disease. Objectives: To characterize the clinical and neuropsychological profiles that constitutes phenotypical markers of the neurocognitive disorders possible Alzheimer subtype. Methods: A descriptive and cross-sectional study of 39 sick persons with ages between 57-85 years, classified according to the DSM-5 criteria, with cognitive mild and major disorder, classified from the etiological point of view in the possible Alzheimer subtype was carried out. Multiple cognitive domains were evaluated (complex attention, memory and learning, executive functions, language, motor and perceptual functions) and a detailed evaluation of the executive functions was made by means of a group of specific neuropsychological tests. Results: The statistical analysis demonstrated that comparing the two study groups with cognitive disorder, significant differences exist as for the level of cognitive performance in all the explored domains, except in the perception and motor functions. Likewise, the results demonstrated that the yielding level for each function evaluated within the domain of the executive functions is significantly different between both groups with cognitive disorder, except for the space orientation. Conclusions: The neuropsychological profile of the cognitive disorder Alzheimer possible subtype was characterized by a disorder in multiple domains, with predominance of the focused executive dysfunction in the areas of the mental flexibility and inhibition of automatisms.

The association between obesity and outcomes in acute pancreatitis: an individual patient data meta-analysis.

OBJECTIVES: There are data to suggest that obesity is associated with local and systemic complications as well as mortality in acute pancreatitis (AP). Cohort studies to date, however, have shown conflicting results from mostly unadjusted analyses. Therefore, we performed an individual patient data meta-analysis with the primary aim to investigate the association between obesity and mortality in AP. Our secondary aim was to investigate the association between obesity and necrosis, organ failure, multiple organ failure, and invasive intervention. PATIENTS AND METHODS: We systematically searched four electronic databases for prospective studies on obesity and outcomes in AP. Researchers of eligible studies were invited to share individual patient data using a standardized data collection form. All end points were investigated with a one-stage mixed effects Poisson model with random intercepts and forced entry of relevant confounders. RESULTS: We included five databases with 1302 patients, of whom 418 (32%) were obese. In total, 466 (36%) patients had necrosis, 328 (25%) had organ failure, 188 (14%) had multiple organ failure, 210 (16%) had an intervention, and 84 (7%) patients died. We found no significant association between obesity and mortality [relative risk (RR) 1.40, 95% confidence interval (CI): 0.89-2.20], necrosis (RR: 1.08, 95% CI: 0.90-1.31) or invasive intervention (RR: 1.10, 95% CI: 0.83-1.47) after adjustment for confounders. However, obesity was independently associated with the development of organ failure (RR: 1.38, 95% CI: 1.11-1.73) and multiple organ failure (RR: 1.81, 95% CI: 1.35-2.42). CONCLUSION: Obesity is independently associated with the development of organ failure and multiple organ failure in AP. However, there is no association between obesity and mortality, necrosis, and an intervention.

El estudio Andalusian Bipolar Family (ABiF): protocolo y descripción de la muestra / The Andalusian Bipolar Family (ABiF) Study: Protocol and sample description

Introducción: Se presenta la primera descripción del estudio denominado Andalusian Bipolar Family (ABiF). Se trata de una investigación longitudinal con familias procedentes de Andalucía (España), que comenzó en 1997, con el objetivo de dilucidar las causas geneticomoleculares del trastorno afectivo bipolar. Desde entonces, esta cohorte ha contribuido a una serie de hallazgos clave, que han sido publicados en revistas internacionales. Sin embargo, el conocimiento sobre las bases genéticas del trastorno en estas familias sigue siendo limitado. Método: El estudio consta de dos fases: en la fase inicial se reclutaron 100 familias con múltiples afectados de trastorno bipolar y otros trastornos del ánimo. La segunda fase del proyecto, actualmente en curso, comenzó en 2013 con el objetivo de realizar un seguimiento de la cohorte de familias reclutadas originalmente. Los objetivos del estudio de seguimiento son: I) recoger nuevos datos clínicos longitudinales; II) realizar una evaluación neuropsicológica detallada, y III) obtener una extensa colección de biomateriales para futuros estudios moleculares. Resultados: El estudio ABiF, por tanto, generará unos recursos valiosos para futuras investigaciones sobre la etiología del trastorno afectivo bipolar; particularmente con respecto a las causas de la alta carga genética del trastorno en las familias con múltiples afectados. Discusión: Se discute el valor de este enfoque en relación con las nuevas tecnologías para la identificación de factores genéticos de alta penetrancia. Estas nuevas tecnologías incluyen la secuenciación del exoma y del genoma completo, y el uso de células madre pluripotentes inducidas u organismos modelo para la determinación de consecuencias funcionales

Introduction: Here, we present the first description of the Andalusian Bipolar Family (ABiF) Study. This longitudinal investigation of families from Andalusia, Spain commenced in 1997 with the aim of elucidating the molecular genetic causes of bipolar affective disorder. The cohort has since contributed to a number of key genetic findings, as reported in international journals. However, insight into the genetic underpinnings of the disorder in these families remains limited. Method: In the initial 1997-2003 study phase, 100 multiplex bipolar disorder and other mood disorder families were recruited. The ongoing second phase of the project commenced in 2013, and involves follow-up of a subgroup of the originally recruited families. The aim of the follow-up investigation is to generate: I) longitudinal clinical data; II) results from detailed neuropsychological assessments; and III) a more extensive collection of biomaterials for future molecular biological studies. Results: The ABiF Study will thus generate a valuable resource for future investigations into the aetiology of bipolar affective disorder; in particular the causes of high disease loading within multiply affected families. Discussion: We discuss the value of this approach in terms of new technologies for the identification of high-penetrance genetic factors. These new technologies include exome and whole genome sequencing, and the use of induced pluripotent stem cells or model organisms to determine functional consequences

Exome sequencing in large, multiplex bipolar disorder families from Cuba.

Bipolar disorder (BD) is a major psychiatric illness affecting around 1% of the global population. BD is characterized by recurrent manic and depressive episodes, and has an estimated heritability of around 70%. Research has identified the first BD susceptibility genes. However, the underlying pathways and regulatory networks remain largely unknown. Research suggests that the cumulative impact of common alleles with small effects explains only around 25-38% of the phenotypic variance for BD. A plausible hypothesis therefore is that rare, high penetrance variants may contribute to BD risk. The present study investigated the role of rare, nonsynonymous, and potentially functional variants via whole exome sequencing in 15 BD cases from two large, multiply affected families from Cuba. The high prevalence of BD in these pedigrees renders them promising in terms of the identification of genetic risk variants with large effect sizes. In addition, SNP array data were used to calculate polygenic risk scores for affected and unaffected family members. After correction for multiple testing, no significant increase in polygenic risk scores for common, BD-associated genetic variants was found in BD cases compared to healthy relatives. Exome sequencing identified a total of 17 rare and potentially damaging variants in 17 genes. The identified variants were shared by all investigated BD cases in the respective pedigree. The most promising variant was located in the gene SERPING1 (p.L349F), which has been reported previously as a genome-wide significant risk gene for schizophrenia. The present data suggest novel candidate genes for BD susceptibility, and may facilitate the discovery of disease-relevant pathways and regulatory networks.

Sarcoma primario de páncreas: una indicación infrecuente de duodenopancreatectomía cefálica / Primary sarcoma of the páncreas: An unusual indication for pancreaticoduodenectomy

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Correction to: A thiotrophic microbial community in an acidic brine lake in Northern Chile.

In Table 1 of the original article, the unit mg/L was incorrectly published as ng/L in the aluminum, chloride, sulphate and OM columns.

A thiotrophic microbial community in an acidic brine lake in Northern Chile.

The endorheic basins of the Northern Chilean Altiplano contain saline lakes and salt flats. Two of the salt flats, Gorbea and Ignorado, have high acidic brines. The causes of the local acidity have been attributed to the occurrence of volcanic native sulfur, the release of sulfuric acid by oxidation, and the low buffering capacity of the rocks in the area. Understanding the microbial community composition and available energy in this pristine ecosystem is relevant in determining the origin of the acidity and in supporting the rationale of conservation policies. Besides, a comparison between similar systems in Australia highlights key microbial components and specific ones associated with geological settings and environmental conditions. Sediment and water samples from the Salar de Gorbea were collected, physicochemical parameters measured and geochemical and molecular biological analyses performed. A low diversity microbial community was observed in brines and sediments dominated by Actinobacteria, Algae, Firmicutes and Proteobacteria. Most of the constituent genera have been reported to be either sulfur oxidizing microorganisms or ones having the potential for sulfur oxidation given available genomic data and information drawn from the literature on cultured relatives. In addition, a link between sulfur oxidation and carbon fixation was observed. In contrast, to acid mine drainage communities, Gorbea microbial diversity is mainly supported by chemolithoheterotrophic, facultative chemolithoautotrophic and oligotrophic sulfur oxidizing populations indicating that microbial activity should also be considered as a causative agent of local acidity.

Adalimumab for Induction of Histological Remission in Moderately to Severely Active Ulcerative Colitis.

BACKGROUND: Histological remission represents a target distinct from endoscopic healing in ulcerative colitis (UC) and seems a better predictor of clinical outcomes. AIMS: The aim of this study was to assess the ability of adalimumab to achieve histological remission in UC patients. METHODS: Single-center, retrospective, open-label study of patients treated with adalimumab. Eligible patients were anti-TNF naïve adults with moderately to severely active UC. The Mayo score including endoscopy was performed at baseline and weeks 8 and 52. Histological activity was scored using the Geboes Index. The primary endpoint was histological remission, defined as a Geboes grade ≤ 3.0, at week 52. RESULTS: We included 34 patients. At week 8, 6 of 34 patients (17.6%) achieved histological remission. At week 52, 9 patients (26.5%, intention to treat; 31%, per protocol) had histological remission. Patients had a significant and progressive reduction in the most severe subgrades of Geboes Index from baseline at weeks 8 and 52. At weeks 8 and 52, 50 and 61.8% of patients achieved mucosal healing (Mayo endoscopic subscore 0-1). All patients who achieved histological remission also had mucosal healing. At week 8, 85.3 and 20.6% of patients achieved clinical response (decrease in Mayo score ≤ 3 points) or remission (Mayo score ≤ 2), respectively. At week 52, the corresponding values were 67.6 and 52.9%, respectively. At week 52, agreement between histological remission and mucosal healing was fair (kappa 0.293). Agreement between histological remission and Mayo endoscopic subscore 0 was good (kappa 0.71). CONCLUSIONS: Adalimumab was able to achieve histological remission in anti-TNF naïve patients with moderately to severely active UC.

The Andalusian Bipolar Family (ABiF) Study: Protocol and sample description. / El estudio Andalusian Bipolar Family (ABiF): protocolo y descripción de la muestra.

INTRODUCTION: Here, we present the first description of the Andalusian Bipolar Family (ABiF) Study. This longitudinal investigation of families from Andalusia, Spain commenced in 1997 with the aim of elucidating the molecular genetic causes of bipolar affective disorder. The cohort has since contributed to a number of key genetic findings, as reported in international journals. However, insight into the genetic underpinnings of the disorder in these families remains limited. METHOD: In the initial 1997-2003 study phase, 100 multiplex bipolar disorder and other mood disorder families were recruited. The ongoing second phase of the project commenced in 2013, and involves follow-up of a subgroup of the originally recruited families. The aim of the follow-up investigation is to generate: i) longitudinal clinical data; ii) results from detailed neuropsychological assessments; and iii) a more extensive collection of biomaterials for future molecular biological studies. RESULTS: The ABiF Study will thus generate a valuable resource for future investigations into the aetiology of bipolar affective disorder; in particular the causes of high disease loading within multiply affected families. DISCUSSION: We discuss the value of this approach in terms of new technologies for the identification of high-penetrance genetic factors. These new technologies include exome and whole genome sequencing, and the use of induced pluripotent stem cells or model organisms to determine functional consequences.

Biomarkers and Metabolic Patterns in the Sediments of Evolving Glacial Lakes as a Proxy for Planetary Lake Exploration.

Oligotrophic glacial lakes in the Andes Mountains serve as models to study the effects of climate change on natural biological systems. The persistent high UV regime and evolution of the lake biota due to deglaciation make Andean lake ecosystems potential analogues in the search for life on other planetary bodies. Our objective was to identify microbial biomarkers and metabolic patterns that represent time points in the evolutionary history of Andean glacial lakes, as these may be used in long-term studies as microscale indicators of climate change processes. We investigated a variety of microbial markers in shallow sediments from Laguna Negra and Lo Encañado lakes (Región Metropolitana, Chile). An on-site immunoassay-based Life Detector Chip (LDChip) revealed the presence of sulfate-reducing bacteria, methanogenic archaea, and exopolymeric substances from Gammaproteobacteria. Bacterial and archaeal 16S rRNA gene sequences obtained from field samples confirmed the results from the immunoassays and also revealed the presence of Alpha-, Beta-, Gamma-, and Deltaproteobacteria, as well as cyanobacteria and methanogenic archaea. The complementary immunoassay and phylogenetic results indicate a rich microbial diversity with active sulfate reduction and methanogenic activities along the shoreline and in shallow sediments. Sulfate inputs from the surrounding volcanic terrains during deglaciation may explain the observed microbial biomarker and metabolic patterns, which differ with depth and between the two lakes. A switch from aerobic and heterotrophic metabolisms to anaerobic ones such as sulfate reduction and methanogenesis in the shallow shores likely reflects the natural evolution of the lake sediments due to deglaciation. Hydrodynamic deposition of sediments creates compartmentalization (e.g., sediments with different structure and composition surrounded by oligotrophic water) that favors metabolic transitions. Similar phenomena would be expected to occur on other planetary lakes, such as those of Titan, where watery niches fed by depositional events would be surrounded by a "sea" of hydrocarbons. Key Words: Glacier lakes-Sedimentation-Prokaryotic metabolisms and biomarkers-Deglaciation-Life detection-Planetary exploration. Astrobiology 18, 586-606.