Ccdc11 is a novel centriolar satellite protein essential for ciliogenesis and establishment of left-right asymmetry

The establishment of left–right (L-R) asymmetry in vertebrates is dependent on the sensory and motile functions of cilia during embryogenesis. Mutations in CCDC11 disrupt L-R asymmetry and cause congenital heart disease in humans, yet the molecular and cellular functions of the protein remain unknown. Here we demonstrate that Ccdc11 is a novel component of centriolar satellites—cytoplasmic granules that serve as recruitment sites for proteins destined for the centrosome and cilium. Ccdc11 interacts with core components of satellites, and its loss disrupts the subcellular organization of satellite proteins and perturbs primary cilium assembly. Ccdc11 colocalizes with satellite proteins in human multiciliated tracheal epithelia, and its loss inhibits motile ciliogenesis. Similarly, depletion of CCDC11 in Xenopus embryos causes defective assembly and motility of cilia in multiciliated epidermal cells. To determine the role of CCDC11 during vertebrate development, we generated mutant alleles in zebrafish. Loss of CCDC11 leads to defective ciliogenesis in the pronephros and within the Kupffer’s vesicle and results in aberrant L-R axis determination. Our results highlight a critical role for Ccdc11 in the assembly and function of motile cilia and implicate centriolar satellite–associated proteins as a new class of proteins in the pathology of L-R patterning and congenital heart disease

Diversity of Life at the Geothermal Subsurface-Surface Interface: The Yellowstone Example Geophysical Monograph Series

Generally, studies of the terrestrial example of Yellowstone National Park indicate that the diversity of microbial life at the geothermal subsurface-surface interface is considerable. On the other hand, experiments in a subsurface well in Biscuit Basin suggest that the Yellowstone subsurface is highly reduced, with minimal in situ subsurface life at this location. The absence of life in the subsurface is likely due to low concentrations of available electron acceptors. Where subsurface thermal waters emerge to the surface, however, in the presence of oxidizing electron acceptors, microbial life blossoms on all growth surfaces at high temperatures. The geothermal subsurface-surface interface in the presence of both electron donors and acceptors, provides the key location for life to thrive and forms the cornerstone of the microbial ecosystem. Through molecular analyses, the identities of organisms present in a community can be determined by their phylogenetic types (phylotypes), their molecular signatures. Molecular sequences allow relationships to other life forms to be inferred. Comparisons of gene sequences of organisms and consideration of the geochemistry of a particular environment can help to explain how this geothermal system functions. Experimental results challenge some popular notions about the kinds of organisms that inhabit the geothermal realms and the energy sources that fuel them. In contrast to the popular notion that representatives of the phylogenetic domain Archaea dominate high-temperature ecosystems, members of the domain Bacteria are most abundant in the Yellowstone ecosystem. Moreover, while sulfur metabolism is generally proposed to be the primary energy source for life in this geothermal system, the main organisms identified by phylotype are related to organisms that utilize hydrogen, not sulfur, for energy. This implies that hydrogen is the main energy source that drives primary productivity in this and potentially other geothermal ecosystems. Primary dependence on hydrogen metabolism could be the common theme for high-temperature life in hydrothermal zones at mid-oceanic ridges, as well as for the earliest life on Earth and, potentially, for life on other planetary bodies

Intact polar lipidome and membrane adaptations of microbial communities inhabiting serpentinite-hosted fluids

The generation of hydrogen and reduced carbon compounds during serpentinization provides sustained energy for microorganisms on Earth, and possibly on other extraterrestrial bodies (e.g., Mars, icy satellites). However, the geochemical conditions that arise from water-rock reaction also challenge the known limits of microbial physiology, such as hyperalkaline pH, limited electron acceptors and inorganic carbon. Because cell membranes act as a primary barrier between a cell and its environment, lipids are a vital component in microbial acclimation to challenging physicochemical conditions. To probe the diversity of cell membrane lipids produced in serpentinizing settings and identify membrane adaptations to this environment, we conducted the first comprehensive intact polar lipid (IPL) biomarker survey of microbial communities inhabiting the subsurface at a terrestrial site of serpentinization. We used an expansive, custom environmental lipid database that expands the application of targeted and untargeted lipodomics in the study of microbial and biogeochemical processes. IPLs extracted from serpentinite-hosted fluid communities were comprised of >90% isoprenoidal and non-isoprenoidal diether glycolipids likely produced by archaeal methanogens and sulfate-reducing bacteria. Phospholipids only constituted ~1% of the intact polar lipidome. In addition to abundant diether glycolipids, betaine and trimethylated-ornithine aminolipids and glycosphingolipids were also detected, indicating pervasive membrane modifications in response to phosphate limitation. The carbon oxidation state of IPL backbones was positively correlated with the reduction potential of fluids, which may signify an energy conservation strategy for lipid synthesis. Together, these data suggest microorganisms inhabiting serpentinites possess a unique combination of membrane adaptations that allow for their survival in polyextreme environments. The persistence of IPLs in fluids beyond the presence of their source organisms, as indicated by 16S rRNA genes and transcripts, is promising for the detection of extinct life in serpentinizing settings through lipid biomarker signatures. These data contribute new insights into the complexity of lipid structures generated in actively serpentinizing environments and provide valuable context to aid in the reconstruction of past microbial activity from fossil lipid records of terrestrial serpentinites and the search for biosignatures elsewhere in our solar system

Regional fresh snowfall microbiology and chemistry are driven by geography in storm-tracked events, Colorado, USA

Snowfall is a global phenomenon highly integrated with hydrology and ecology. Forays into studying bioaerosols and their dependence on aeolian movement are largely constrained to either precipitation-independent analyses or in silico models. Though snowpack and glacial microbiological studies have been conducted, little is known about the biological component of meteoric snow. Through culture-independent phylogenetic and geochemical analyses, we show that the geographical location at which snow precipitates determines snowfall’s geochemical and microbiological composition. Storm-tracking, furthermore, can be used as a valuable environmental indicator to trace down what factors are influencing bioaerosols. We estimate annual aeolian snowfall deposits of up to ∼10 kg of bacterial/archaeal biomass per hectare along our study area of the eastern Front Range in Colorado. The dominant kinds of microbiota captured in an analysis of seven snow events at two different locations, one urban, one rural, across the winter of 2016/2017 included phyla Proteobacteria, Bacteroidetes, Firmicutes, and Acidobacteria, though a multitude of different kinds of organisms were found in both. Taxonomically, Bacteroidetes were more abundant in Golden (urban plain) snow while Proteobacteria were more common in Sunshine (rural mountain) samples. Chemically, Golden snowfall was positively correlated with some metals and anions. The work also hints at better informing the “everything is everywhere” hypotheses of the microbial world and that atmospheric transport of microbiota is not only common, but is capable of disseminating vast amounts of microbiota of different physiologies and genetics that then affect ecosystems globally. Snowfall, we conclude, is a significant repository of microbiological material with strong implications for both ecosystem genetic flux and general bio-aerosol theory

Diverse capacity for 2-methylhopanoid production correlates with a specific ecological niche

Molecular fossils of 2-methylhopanoids are prominent biomarkers in modern and ancient sediments that have been used as proxies for cyanobacteria and their main metabolism, oxygenic photosynthesis. However, substantial culture and genomic-based evidence now indicates that organisms other than cyanobacteria can make 2-methylhopanoids. Because few data directly address which organisms produce 2-methylhopanoids in the environment, we used metagenomic and clone library methods to determine the environmental diversity of hpnP, the gene encoding the C-2 hopanoid methylase. Here we show that hpnP copies from alphaproteobacteria and as yet uncultured organisms are found in diverse modern environments, including some modern habitats representative of those preserved in the rock record. In contrast, cyanobacterial hpnP genes are rarer and tend to be localized to specific habitats. To move beyond understanding the taxonomic distribution of environmental 2-methylhopanoid producers, we asked whether hpnP presence might track with particular variables. We found hpnP to be significantly correlated with organisms, metabolisms and environments known to support plant–microbe interactions (P-value<10^−6); in addition, we observed diverse hpnP types in closely packed microbial communities from other environments, including stromatolites, hot springs and hypersaline microbial mats. The common features of these niches indicate that 2-methylhopanoids are enriched in sessile microbial communities inhabiting environments low in oxygen and fixed nitrogen with high osmolarity. Our results support the earlier conclusion that 2-methylhopanoids are not reliable biomarkers for cyanobacteria or any other taxonomic group, and raise the new hypothesis that, instead, they are indicators of a specific environmental niche

Unexpected diversity and complexity of the Guerrero Negro hypersaline microbial mat

Author Posting. © The Author(s), 2006. This is the author's version of the work. It is posted here by permission of American Society for Microbiology for personal use, not for redistribution. The definitive version was published in Applied and Environmental Microbiology 72 (2006): 3685-3695, doi:10.1128/AEM.72.5.3685-3695.2006.We applied nucleic acids-based molecular methods, combined with estimates of biomass (ATP), pigments and microelectrode measurements of chemical gradients, to map microbial diversity vertically on the mm-scale in a hypersaline microbial mat from Guerrero Negro, Baja California Sur, Mexico. To identify the constituents of the mat, small-subunit ribosomal RNA genes were amplified by PCR from community genomic DNA extracted from layers, cloned and sequenced. Bacteria dominated the mat and displayed unexpected and unprecedented diversity. The majority (1336) of 1586 bacterial 16S rRNA sequences generated were unique, representing 752 species (≥97% rRNA sequence identity) in 42 of the main bacterial phyla, including 15 novel candidate phyla. The diversity of the mat samples differentiated according to the chemical milieu defined by concentrations of O2 and H2S. Chloroflexi formed the majority of the biomass by percentage of bulk rRNA and of clones in rRNA gene libraries. This result contradicts the general belief that Cyanobacteria dominate these communities. Although Cyanobacteria constituted a large fraction of the biomass in the upper few mm (>80% of total rRNA and photosynthetic pigments), Chloroflexi sequences were conspicuous throughout the mat. Filamentous Chloroflexi were identified by fluorescent in-situ hybridization within the polysaccharide sheaths of the prominent cyanobacterium Microcoleus chthonoplastes in addition to free-living in the mat. The biological complexity of the mat far exceeds that observed in other polysaccharide-rich microbial ecosystems, such as human and mouse distal guts, and suggests that positive feedbacks exist between chemical complexity and biological diversity.R. Ley was supported in part by an NRC- NASA Astrobiology Institutes Post Doctoral Associateship, J. Spear by an Agouron Institute postdoctoral fellowship. This work was supported by the NASA Cooperative Agreement with the University of Colorado Center for Astrobiology to N. R. Pace

Low-Temperature Sulfidic-Ice Microbial Communities, Borup Fiord Pass, Canadian High Arctic

A sulfur-dominated supraglacial spring system found at Borup Fiord Pass (BFP), Ellesmere Island, Nunavut, Canada, is a unique sulfur-on-ice system expressed along the toe of a glacier. BFP has an intermittent flowing, subsurface-derived, glacial spring that creates a large white-yellow icing (aufeis) that extends down-valley. Over field campaigns in 2014, 2016, and 2017, numerous samples were collected and analyzed for both microbial community composition and aqueous geochemistry. Samples were collected from multiple site types: spring discharge fluid, aufeis (spring-derived ice), melt pools with sedimented cryoconite material, and mineral precipitate scrapings, to probe how microbial communities differed between site types in a dynamic freeze/thaw sulfur-rich system. Dissolved sulfate varied between 0.07 and 11.6 mM and was correlated with chloride concentrations, where the fluids were saltiest among spring fluids. The highest sulfate samples exhibited high dissolved sulfide values between 0.22 and 2.25 mM. 16S rRNA gene sequencing from melt pool and aufeis samples from the 2014 campaign were highly abundant in operational taxonomic units (OTUs) closely related to sulfur-oxidizing microorganisms (SOM; Sulfurimonas, Sulfurovum, and Sulfuricurvum). Subsequent sampling 2 weeks later had fewer SOMs and showed an increased abundance of the genus Flavobacterium. Desulfocapsa, an organism that specializes in the disproportionation of inorganic sulfur compounds was also found. Samples from 2016 and 2017 revealed that microorganisms present were highly similar in community composition to 2014 samples, primarily echoed by the continued presence of Flavobacterium sp. Results suggest that while there may be acute events where sulfur cycling organisms dominate, a basal community structure appears to dominate over time and site type. These results further enhance our knowledge of low-temperature sulfur systems on Earth, and help to guide the search for potential life on extraterrestrial worlds, such as Europa, where similar low-temperature sulfur-rich conditions may exist

Spatial and temporal dynamics at an actively silicifying hydrothermal system

Steep Cone Geyser is a unique geothermal feature in Yellowstone National Park (YNP), Wyoming, actively gushing silicon-rich fluids along outflow channels possessing living and actively silicifying microbial biomats. To assess the geomicrobial dynamics occurring temporally and spatially at Steep Cone, samples were collected at discrete locations along one of Steep Cone’s outflow channels for both microbial community composition and aqueous geochemistry analysis during field campaigns in 2010, 2018, 2019, and 2020. Geochemical analysis characterized Steep Cone as an oligotrophic, surface boiling, silicious, alkaline-chloride thermal feature with consistent dissolved inorganic carbon and total sulfur concentrations down the outflow channel ranging from 4.59 ± 0.11 to 4.26 ± 0.07 mM and 189.7 ± 7.2 to 204.7 ± 3.55 μM, respectively. Furthermore, geochemistry remained relatively stable temporally with consistently detectable analytes displaying a relative standard deviation &lt;32%. A thermal gradient decrease of ~55°C was observed from the sampled hydrothermal source to the end of the sampled outflow transect (90.34°C ± 3.38 to 35.06°C ± 7.24). The thermal gradient led to temperature-driven divergence and stratification of the microbial community along the outflow channel. The hyperthermophile Thermocrinis dominates the hydrothermal source biofilm community, and the thermophiles Meiothermus and Leptococcus dominate along the outflow before finally giving way to more diverse and even microbial communities at the end of the transect. Beyond the hydrothermal source, phototrophic taxa such as Leptococcus, Chloroflexus, and Chloracidobacterium act as primary producers for the system, supporting heterotrophic growth of taxa such as Raineya, Tepidimonas, and Meiothermus. Community dynamics illustrate large changes yearly driven by abundance shifts of the dominant taxa in the system. Results indicate Steep Cone possesses dynamic outflow microbial communities despite stable geochemistry. These findings improve our understanding of thermal geomicrobiological dynamics and inform how we can interpret the silicified rock record

Physical and biological variables affecting seabird distributions during the upwelling season of the northern California Current

Author Posting. © The Authors, 2004. This is the author's version of the work. It is posted here by permission of Elsevier B. V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 52 (2005): 123-143, doi:10.1016/j.dsr2.2004.08.016.As a part of the GLOBEC-Northeast Pacific project, we investigated variation in the abundance of marine birds in the context of biological and physical habitat conditions in the northern portion of the California Current System (CCS) during cruises during the upwelling season 2000. Continuous surveys of seabirds were conducted simultaneously in June (onset of upwelling) and August (mature phase of upwelling) with ocean properties quantified using a towed, undulating vehicle and a multi-frequency bioacoustic instrument (38-420 kHz). Twelve species of seabirds contributed 99% of the total community density and biomass. Species composition and densities were similar to those recorded elsewhere in the CCS during earlier studies of the upwelling season. At a scale of 2-4 km, physical and biological oceanographic variables explained an average of 25% of the variation in the distributions and abundance of the 12 species. The most important explanatory variables (among 14 initially included in each multiple regression model) were distance to upwelling-derived frontal features (center and edge of coastal jet, and an abrupt, inshore temperature gradient), sea-surface salinity, acoustic backscatter representing various sizes of prey (smaller seabird species were associated with smaller prey and the reverse for larger seabird species), and chlorophyll concentration. We discuss the importance of these variables in the context of what factors may be that seabirds use to find food. The high seabird density in the Heceta Bank and Cape Blanco areas indicate them to be refuges contrasting the low seabird densities currently found in most other parts of the CCS, following decline during the recent warm regime of the Pacific Decadal Oscillation.Support from National Science Foundation Grant OCE-0001035, National Oceanic and Atmospheric Administration (NOAA)/Woods Hole Oceanographic Institution-CICOR Grant NA17RJ1223 is gratefully acknowledged

Ischaemic stroke, haemorrhage and mortality in elderly patients with chronic kidney disease newly started on anticoagulation for atrial fibrillation: a population-based study from UK primary care

Objective To assess the association between anticoagulation, ischaemic stroke, gastrointestinal and cerebral haemorrhage, and all cause mortality in older people with atrial fibrillation and chronic kidney disease. Design Propensity matched, population based, retrospective cohort analysis from January 2006 through December 2016. Setting The Royal College of General Practitioners Research and Surveillance Centre database population of almost 2.73 million patients from 110 general practices across England and Wales. Participants Patients aged 65 years and over with a new diagnosis of atrial fibrillation and estimated glomerular filtration rate (eGFR) of <50 mL/min/1.73m2, calculated using the chronic kidney disease epidemiology collaboration creatinine equation. Patients with a previous diagnosis of atrial fibrillation or receiving anticoagulation in the preceding 120 days were excluded, as were patients requiring dialysis and recipients of renal transplants. Intervention Receipt of an anticoagulant prescription within 60 days of atrial fibrillation diagnosis. Main outcome measures Ischaemic stroke, cerebral or gastrointestinal haemorrhage, and all cause mortality. Results 6977 patients with chronic kidney disease and newly diagnosed atrial fibrillation were identified, of whom 2434 were on anticoagulants within 60 days of diagnosis and 4543 were not. 2434 pairs were matched using propensity scores by exposure to anticoagulant or none and followed for a median of 506 days. The crude rates for ischaemic stroke and haemorrhage were 4.6 and 1.2 after taking anticoagulants and 1.5 and 0.4 in patients who were not taking anticoagulant per 100 person years, respectively. The hazard ratios for ischaemic stroke, haemorrhage, and all cause mortality for those on anticoagulants were 2.60 (95% confidence interval 2.00 to 3.38), 2.42 (1.44 to 4.05), and 0.82 (0.74 to 0.91) compared with those who received no anticoagulation. Conclusion Giving anticoagulants to older people with concomitant atrial fibrillation and chronic kidney disease was associated with an increased rate of ischaemic stroke and haemorrhage but a paradoxical lowered rate of all cause mortality. Careful consideration should be given before starting anticoagulants in older people with chronic kidney disease who develop atrial fibrillation. There remains an urgent need for adequately powered randomised trials in this population to explore these findings and to provide clarity on correct clinical management