A5007741305- Polar Research and Ecology
- Microbial Community Ecology and Physiology
- Cryospheric studies and observations
- Methane Hydrates and Related Phenomena
- Arctic and Antarctic ice dynamics
- Climate change and permafrost
- Indigenous Studies and Ecology
- Diatoms and Algae Research
- Marine and coastal ecosystems
- Geology and Paleoclimatology Research
- Biocrusts and Microbial Ecology
- thermodynamics and calorimetric analyses
- Astro and Planetary Science
- Planetary Science and Exploration
- Genomics and Phylogenetic Studies
- Lichen and fungal ecology
- Per- and polyfluoroalkyl substances research
- Food Industry and Aquatic Biology
- Atmospheric chemistry and aerosols
- Muscle metabolism and nutrition
- Physiological and biochemical adaptations
- Chemical Analysis and Environmental Impact
- Winter Sports Injuries and Performance
- Ion-surface interactions and analysis
- Pharmacological Effects of Medicinal Plants
University of Washington
2006-2025
Johns Hopkins University Applied Physics Laboratory
2008-2025
University of Washington Applied Physics Laboratory
2008-2019
Seattle University
1998-2019
Institute of Biological, Environmental and Rural Sciences
2018
Aberystwyth University
2018
Earth and Space Research
2005-2007
NASA Astrobiology Institute
2004
Kiel University
1998
ABSTRACT Arctic wintertime sea-ice cores, characterized by a temperature gradient of −2 to −20°C, were investigated better understand constraints on bacterial abundance, activity, and diversity at subzero temperatures. With the fluorescent stains 4′,6′-diamidino-2-phenylindole 2HCl (DAPI) (for DNA) 5-cyano-2,3-ditoyl tetrazolium chloride (CTC) O 2 -based respiration), abundances total, particle-associated (>3-μm), free-living, actively respiring bacteria determined for ice-core samples...
Abstract Microbial populations and activity within sea ice have been well described based on bulk measurements from melted sea-ice samples. However, melting destroys the micro-environments matrix does not allow for examination of microbial at a spatial scale relevant to organism. Here, we describe development new method allowing microscopic observations bacteria localized three-dimensional network brine inclusions in under situ conditions. Conventional bacterial staining procedures, using...
Psychro-active bacteria, important constituents of polar ecosystems, have a unique ability to remain active at temperatures below 0 degrees C, yet it is not known what extent the composition their outer cell surfaces aids in low-temperature viability. In this study, aqueous suspensions five strains Arctic psychro-active marine bacteria (PAMB) (mostly sea-ice isolates), were characterized by surface-enhanced Raman spectroscopy (SERS) and compared with SERS spectra from E. coli P. aerigunosa....
Snow overlays the majority of Greenland Ice Sheet (GrIS). However, there is very little information available on microbiological assemblages that are associated with this vast and climate-sensitive landscape. In study, structure diversity snow microbial from two regions western GrIS ice margin were investigated through sequencing small subunit ribosomal RNA genes. The origins microbiota by examining correlations to molecular data obtained marine, soil, freshwater atmospheric environments...
Few halophilic strains have been examined in detail for their culturability and metabolic activity at subzero temperatures, within the ice matrix, over longer term. Here, we examine three Arctic with varied salinity tolerances: Colwellia psychrerythraea str. 34H (Cp34H), Psychrobacter sp. 7E (P7E), Halomonas 3E (H3E). As a proxy biosignatures, observable cells, activity, recoverability on 12-month incubations −5, −10 −36 °C. To further develop life-detection strategies, also study short-term...
Since the discovery of perchlorates in martian soils, astrobiologists have been curious if and how life could survive these low-water, high-salt environments. Perchlorates induce chaotropic oxidative stress but can also confer increased cold tolerance some extremophiles. Though bacterial survival has demonstrated at subzero temperatures perchlorate solution, proteomic analysis cells growing an environment like regolith brines—perchlorate with temperatures—has yet to be demonstrated. By...
Abstract. Even though studies of Arctic ice forming particles suggest that a bacterial or viral source derived from open leads could be important for formation in clouds (Bigg and Leck, 2001), the nucleation potential most polar marine psychrophiles viruses has not been examined under conditions more closely resembling those atmosphere. In this paper, we activity (INA) several representative Antarctic sea-ice isolates Colwellia phage virus. High-resolution spectra were obtained droplets...
The mechanisms that allow psychrophilic bacteria to remain metabolically active at subzero temperatures result from form and function of their proteins. We present first proteomic evidence physiological changes the marine psychrophile Colwellia psychrerythraea 34H (Cp34H) after exposure (-1, -10°C in ice) through 8 weeks. Protein abundance was compared between different treatments understand effects temperature time, independently jointly, within cells transitioning to, being maintained ice....
Abstract. Field investigations of the properties heavily melted “rotten” Arctic sea ice were carried out on shorefast and drifting off coast Utqiaġvik (formerly Barrow), Alaska, during melt season. While no formal criteria exist to qualify when becomes rotten, objective this study was sample melting at point which its structural optical are sufficiently advanced beyond peak summer Baseline data physical (temperature, salinity, density, microstructure) (light scattering) recorded in May June...
ABSTRACT We examined the Arctic bacterium Colwellia psychrerythraea strain 34H for motility at temperatures from −1 to −15°C by using transmitted-light microscopy in a temperature-controlled laboratory. The results, showing −10°C, indicate much lower be permissive of than previously reported (5°C), with implications microbial activity frozen environments.
Colwellia psychrerythraea is a marine psychrophilic bacterium known for its remarkable ability to maintain activity during long-term exposure extreme subzero temperatures and correspondingly high salinities in sea ice. These microorganisms must have adaptations both salinity low temperature survive, be metabolically active, or grow the Here, we report on an experimental design that allowed us monitor culturability, cell abundance, proteomic signatures of C. strain 34H (Cp34H) brines...
The quantitative role of carbon‐rich compounds for bacterial carbon demand can vary with nutrient availability. This study is the first to investigate effect concentrations on uptake a compound (glucose) along naturally occurring gradient. Seawater was collected from varying depths at six stations across gradient between nutrient‐poor North Pacific gyre and nutrient‐rich sub‐ Arctic gyre. Ambient free glucose, glucose uptake, production, were determined Incubations carried out determine...
Abstract. Field investigations of the properties heavily melted "rotten" Arctic sea ice were carried out on shorefast and drifting off coast Utqiaġvik (formerly Barrow), Alaska during melt season. While no formal criteria exist to qualify when becomes "rotten", objective this study was sample melting at point where its structural optical are sufficiently advanced beyond peak summer Baseline data physical (temperature, salinity, density, microstructure) (light scattering) recorded in May June...
Abstract. Even though studies of Arctic ice forming particles suggest that a bacterial or viral source derived from open leads could be important for cloud formation in the (Bigg and Leck, 2001), nucleation potential most polar marine psychrophiles viruses has not been examined under conditions more closely resembling those atmosphere. In this paper, we activity (INA) several representative Antarctic sea-ice isolates Colwellia phage virus. High-resolution spectra were obtained droplets...
To better understand constraints on bacteria at extremely low temperatures in ice, we describe here the adaptation of methods previously developed for sea ice to high magnification imaging within fluid inclusions Arctic lake under insitu conditions. Bacterial staining procedures, using DNA-specific fluorescent stain DAPI, epifluorescence microscopy and image analysis were applied lake-ice sections situ temperature (-5°C). Abundances total, attached, free-living metabolically active also...