First posted January 19, 2021 For additional information, contact: Alaska Regional Director4210 University DriveAnchorage, AK 99508907–786–7091 The U.S. Geological Survey (USGS), in collaboration with university, Federal, Tribal, and independent partners, conducts fundamental research on the distribution, vulnerability, and importance of permafrost in arctic and boreal ecosystems. Scientists, land managers, and policy makers use USGS data to help make decisions for development, wildlife habitat, and other needs. Native villages and cities can forecast landscape change and where soils are vulnerable to thaw with more certainty. The scientific community can use USGS data to develop scenarios of future permafrost change.
A dark-green-pigmented marine bacterium, previously designated D2, which produces components that are inhibitory to common marine fouling organisms has been characterized and assessed for taxonomic assignment. Based on direct double-stranded sequencing of the 16S rRNA gene, D2T was found to show the highest similarity (93%) to members of the genus Pseudoalteromonas. The G+C content of D2T is 42 mol%, and it is a facultatively anaerobic rod and oxidase-positive. D2T is motile by a sheathed polar flagellum, exhibited non-fermentative metabolism and required sodium ions for growth. The strain was not capable of using citrate, fructose, sucrose, sorbitol and glycerol but it utilizes mannose and maltose and hydrolyses gelatin. The molecular evidence, together with phenotypic characteristics, showed that this bacterium which produces an antifouling agent constitutes a new species of the genus Pseudoalteromonas. The name Pseudoalteromonas tunicata is proposed for this bacterium, and the type strain is D2T (= CCUG 26757T).
Abstract The impact of permafrost thaw on hydrologic, thermal, and biotic processes remains uncertain, in part due to limitations in subsurface measurement capabilities. To better understand subsurface processes in thermokarst environments, we collocated geophysical and biogeochemical instruments along a thaw gradient between forested permafrost and collapse‐scar bogs at the Alaska Peatland Experiment site near Fairbanks, Alaska. Ambient seismic noise monitoring provided continuous high‐temporal resolution measurements of water and ice saturation changes. Maps of seismic velocity change identified areas of large summertime velocity reductions nearest the youngest bog, indicating potential thaw and expansion at the bog margin. These results corresponded well with complementary borehole nuclear magnetic resonance measurements of unfrozen water content with depth, which showed permafrost soils nearest the bog edges contained the largest amount of unfrozen water along the study transect, up to 25% by volume. In situ measurements of methane within permafrost soils revealed high concentrations at these bog‐edge locations, up to 30% soil gas. Supra‐permafrost talik zones were observed at the bog margins, indicating talik formation and perennial liquid water may drive lateral bog expansion and enhanced permafrost carbon losses preceding thaw. Comparison of seismic monitoring with wintertime surface carbon dioxide fluxes revealed differential responses depending on time and proximity to the bogs, capturing the controlling influence of subsurface water and ice on microbial activity and surficial emissions. This study demonstrates a multidisciplinary approach for gaining new understanding of how subsurface physical properties influence greenhouse gas production, emissions, and thermokarst development.
A 15-month-old boy presented with hypertension, edema, heavy proteinuria, gross hematuria and renal insufficiency. A renal biopsy was consistent with classical membranoproliferative glomerulonephritis type I. Although usually thought of as a disease in older children and young adults, membranoproliferative glomerulonephritis can occur as early as the second year of life.
Indirect immunofluorescence was used to quantify the seasonal variation of four halophilic aerobic Antarctic bacteria in Antarctic saline lakes from July 1990 to January 1991. Antibodies were raised against type strains from the Australian Collection of Antarctic Microorganisms. During summer, all four serogroups were identified in the aerobic waters of lakes with total dissolved salts above 61%. Maximal abundances of Halomonas meridiana, H. subglaciescola and Flavobacterium gondwanense serogroups were observed at discrete depths within the water column in the two most hypersaline lakes at about midsummer, coincident with the time of maximum sunlight and the commencement of the summer thaw. At this time the Halomonas spp. serogroups comprised up to 40% of the total bacteria and the F. gondwanense serogroup up to 10% of the total bacteria. The F. salegens serogroup was in low numbers (>2% of total bacteria) in some aerobic waters. Up to 2% of the total bacterial populations in the lakes were autofluorescent or stained non-specifically. Dissolved organic carbon values were measured throughout the sampling period and correlated well with total bacterial numbers but not with changes in species composition. Change in species abundance, as indicated by immunofluorescence, was not reflected in the total bacterial count, indicating compositional change of the total bacterial population.
