Sulfur oxidation and reduction are coupled to nitrogen fixation in the roots of the salt marsh foundation plant Spartina alterniflora.

Heterotrophic activity, primarily driven by sulfate-reducing prokaryotes, has traditionally been linked to nitrogen fixation in the root zone of coastal marine plants, leaving the role of chemolithoautotrophy in this process unexplored. Here, we show that sulfur oxidation coupled to nitrogen fixation is a previously overlooked process providing nitrogen to coastal marine macrophytes. In this study, we recovered 239 metagenome-assembled genomes from a salt marsh dominated by the foundation plant Spartina alterniflora, including diazotrophic sulfate-reducing and sulfur-oxidizing bacteria. Abundant sulfur-oxidizing bacteria encode and highly express genes for carbon fixation (RuBisCO), nitrogen fixation (nifHDK) and sulfur oxidation (oxidative-dsrAB), especially in roots stressed by sulfidic and reduced sediment conditions. Stressed roots exhibited the highest rates of nitrogen fixation and expression level of sulfur oxidation and sulfate reduction genes. Close relatives of marine symbionts from the Candidatus Thiodiazotropha genus contributed ~30% and ~20% of all sulfur-oxidizing dsrA and nitrogen-fixing nifK transcripts in stressed roots, respectively. Based on these findings, we propose that the symbiosis between S. alterniflora and sulfur-oxidizing bacteria is key to ecosystem functioning of coastal salt marshes.

Massive peatland carbon banks vulnerable to rising temperatures.

Peatlands contain one-third of the world's soil carbon (C). If destabilized, decomposition of this vast C bank could accelerate climate warming; however, the likelihood of this outcome remains unknown. Here, we examine peatland C stability through five years of whole-ecosystem warming and two years of elevated atmospheric carbon dioxide concentrations (eCO2). Warming exponentially increased methane (CH4) emissions and enhanced CH4 production rates throughout the entire soil profile; although surface CH4 production rates remain much greater than those at depth. Additionally, older deeper C sources played a larger role in decomposition following prolonged warming. Most troubling, decreases in CO2:CH4 ratios in gas production, porewater concentrations, and emissions, indicate that the peatland is becoming more methanogenic with warming. We observed limited evidence of eCO2 effects. Our results suggest that ecosystem responses are largely driven by surface peat, but that the vast C bank at depth in peatlands is responsive to prolonged warming.

Stability of peatland carbon to rising temperatures.

Peatlands contain one-third of soil carbon (C), mostly buried in deep, saturated anoxic zones (catotelm). The response of catotelm C to climate forcing is uncertain, because prior experiments have focused on surface warming. We show that deep peat heating of a 2 m-thick peat column results in an exponential increase in CH4 emissions. However, this response is due solely to surface processes and not degradation of catotelm peat. Incubations show that only the top 20-30 cm of peat from experimental plots have higher CH4 production rates at elevated temperatures. Radiocarbon analyses demonstrate that CH4 and CO2 are produced primarily from decomposition of surface-derived modern photosynthate, not catotelm C. There are no differences in microbial abundances, dissolved organic matter concentrations or degradative enzyme activities among treatments. These results suggest that although surface peat will respond to increasing temperature, the large reservoir of catotelm C is stable under current anoxic conditions.

Whole-body cryostimulation (cryotherapy) provides benefits for fatigue and functional status in multiple sclerosis patients. A case-control study.

OBJECTIVES: To study the effects of whole-body cryostimulation (WBC) on fatigue and functional status in multiple sclerosis (MS) patients with different levels of fatigue. SUBJECTS AND METHODS: Two groups of 24 MS patients with fatigue were studied. At the beginning of the study, the first group presented a Fatigue Severity Scale (FSS) score between 38 and 42 (low-fatigue (LF) group), and the second group had an FSS score between 48 and 52 (high-fatigue (HF) group). Both groups were matched for age and sex. All patients were exposed to 10.3-min session of WBC (one exposure per day at -110°C or lower). Functional status was assessed before and after the series of WBC exposures using the Rivermead Motor Assessment (RMA), the Multiple Sclerosis Impact Scale (MSIS-29), and the Expanded Disability Status Scale (EDSS). The RMA was estimated in three sections: gross function (RMA1), leg and trunk (RMA2), and arm (RMA3). MSIS-29 consists of two subscales assessing the physical (MSIS-29-PHYS) and psychological (MSIS-29-PSYCH) status. RESULTS: In both groups, the WBC sessions induced a significant improvement in the functional status and in the feeling of fatigue. However, the changes observed in HF patients were significantly greater than those observed in LF patients, especially in the MSIS-29-PHYS, MSIS-29-PSYCH, RMA1, and RMA3. The changes observed in the EDSS, RMA2, and FSS were similar in both groups. CONCLUSIONS: WBC appears to be effective in improving functional status and the feeling of fatigue in patients with MS and especially in those who are the most fatigued.

Microbial responses to the Deepwater Horizon oil spill: from coastal wetlands to the deep sea.

The Deepwater Horizon oil spill in the northern Gulf of Mexico represents the largest marine accidental oil spill in history. It is distinguished from past spills in that it occurred at the greatest depth (1,500 m), the amount of hydrocarbon gas (mostly methane) lost was equivalent to the mass of crude oil released, and dispersants were used for the first time in the deep sea in an attempt to remediate the spill. The spill is also unique in that it has been characterized with an unprecedented level of resolution using next-generation sequencing technologies, especially for the ubiquitous hydrocarbon-degrading microbial communities that appeared largely to consume the gases and to degrade a significant fraction of the petroleum. Results have shown an unexpectedly rapid response of deep-sea Gammaproteobacteria to oil and gas and documented a distinct succession correlated with the control of the oil flow and well shut-in. Similar successional events, also involving Gammaproteobacteria, have been observed in nearshore systems as well.

Nutritional status and quality of life in different populations of older people in Poland.

BACKGROUND/OBJECTIVES: To estimate the potential association of three distinct nutritional status measures (body mass index (BMI), calf circumference (CC) and the Mini Nutritional Assessment (MNA)) with health-related quality of life (HRQL) assessed with Euroqol 5D questionnaire in different populations of elderly people in Poland. SUBJECTS/METHODS: The study group was comprised of 1003 community-dwelling subjects from the urban environment, 890 subjects from the rural environment and 879 subjects from an institutional environment (nursing homes). Bivariate and multivariate associations were identified between nutritional status measures and HRQL adjusted for demographic and social variables, health status, physical function and mental status. RESULTS: Nutrition status indices (BMI, CC and MNA) were generally higher in the urban than in the rural environment and clearly worse in institutionalised elderly. In both community-dwelling groups, BMI and CC were negatively related to several Euroqol scores. In institutional residents, of opposite relationships were observed: higher values of these variables were connected with less frequent reporting of problems in Euroqol. In all the three groups, associations between HRQL scores and MNA were very similar: higher values of MNA were significantly connected with less frequent reporting of problems in Euroqol. CONCLUSIONS: BMI and CC, as overweight/obesity measures, are independent predictors of lower HRQL in urban and rural community-dwelling seniors and higher HRQL in institutionalised elderly. Poor nutritional state as measured by MNA is a similar determinant of well-being in all the three environments. This different relationship of popular overweight/obesity measures to HRQL should be taken into account while designing care for older people.

Validation of the modified mini nutritional assessment short-forms in different populations of older people in Poland.

OBJECTIVE: To assess the usefulness in different populations of elderly people in Poland of both modified versions of Mini Nutritional Assessment Short-Forms (MNA-SFs) with a three-category scoring classification: one using BMI (MNA-SF-BMI) and another using calf circumference (MNA-SF-CC). SETTING AND PARTICIPANTS: A group of 932 community-dwelling subjects from the urban environment, 812 subjects from the rural environment and 859 subjects from an institutional environment (nursing homes). MEASUREMENTS: Agreement between both MNA-SFs and the MNA full form. RESULTS: MNA-SF-BMI correctly classified 84.12%, 82.51% and 81.84% of subjects from urban, rural and institutional environment, respectively. For MNA-SF-CC those values were 82.4%, 71.8% and 76.6%, respectively. The sensitivity and specificity of MNA-SF-BMI and MNA-SF-CC against full MNA in screening for "at risk/malnutrition" and "malnutrition" were generally very high, except for relatively lower sensitivity (74.1%) when screening for "malnutrition" with MNA-SF-CC in nursing homes. CONCLUSION: Both MNA-SFs can be recommended as screening tools in assessing the nutritional state of the community-dwelling and institutionalised elderly in Poland. The full version of the MNA confirmed the results of MNA-SFs in this group. The "classic" MNA-SF using BMI was found to perform better than the MNA-SF-CC. The MNA-SF-CC should be used only when measuring BMI is not possible. While using MNA-SF-CC in nursing homes, a higher MNA-SF-CC cut-point of eleven should be rather used in this population to screen for "at risk/malnutrition".

Microbial community structure and activity linked to contrasting biogeochemical gradients in bog and fen environments of the Glacial Lake Agassiz Peatland.

The abundances, compositions, and activities of microbial communities were investigated at bog and fen sites in the Glacial Lake Agassiz Peatland of northwestern Minnesota. These sites contrast in the reactivity of dissolved organic matter (DOM) and the presence or absence of groundwater inputs. Microbial community composition was characterized using pyrosequencing and clone library construction of phylogenetic marker genes. Microbial distribution patterns were linked to pH, concentrations of dissolved organic carbon and nitrogen, C/N ratios, optical properties of DOM, and activities of laccase and peroxidase enzymes. Both bacterial and archaeal richness and rRNA gene abundance were >2 times higher on average in the fen than in the bog, in agreement with a higher pH, labile DOM content, and enhanced enzyme activities in the fen. Fungi were equivalent to an average of 1.4% of total prokaryotes in gene abundance assayed by quantitative PCR. Results revealed statistically distinct spatial patterns between bacterial and fungal communities. Fungal distribution did not covary with pH and DOM optical properties and was vertically stratified, with a prevalence of Ascomycota and Basidiomycota near the surface and much higher representation of Zygomycota in the subsurface. In contrast, bacterial community composition largely varied between environments, with the bog dominated by Acidobacteria (61% of total sequences), while the Firmicutes (52%) dominated in the fen. Acetoclastic Methanosarcinales showed a much higher relative abundance in the bog, in contrast to the dominance of diverse hydrogenotrophic methanogens in the fen. This is the first quantitative and compositional analysis of three microbial domains in peatlands and demonstrates that the microbial abundance, diversity, and activity parallel with the pronounced differences in environmental variables between bog and fen sites.

Dehalogenation of 2,6-dibromobiphenyl and 2,3,4,5,6-pentachlorobiphenyl in contaminated estuarine sediment.

Estuarine sediments from a USEPA Superfund site in coastal Georgia were extensively contaminated with Aroclor 1268, a mixture of highly chlorinated polychlorinated biphenyls used by a former chlor-alkali plant. Batch slurries of contaminated sediment were incubated for 1 yr with amendments of 2,6-dibromobiphenyl (26-BB) and 2,3,4,5,6-pentachlorobiphenyl (23456-CB) under anaerobic, sulfate-reducing conditions and different pH (5.5-7.5). Organic extracts of slurry sub-samples in a time series were analyzed by congener-specific GC-MS. Dechlorination of 23456-CB was pH dependent and occurred via two routes with the sequential loss of (1) meta and para chlorines and (2) para, ortho, and meta chlorines. Quantitative dehalogenation of 26-BB was observed at all pH. Supplementation of nonachlorobiphenyls (as primers) did not induce dechlorination of native Aroclor 1268 nor of the primers themselves. While contaminated estuarine sediments possess microbial consortia with diverse dehalogenating activities, lack of dechlorination of Aroclor 1268 and spiked nonachlorobiphenyl congeners suggests a bioavailability limitation or enzyme-substrate incompatibilities.

Growth and phylogenetic properties of novel bacteria belonging to the epsilon subdivision of the Proteobacteria enriched from Alvinella pompejana and deep-sea hydrothermal vents.

Recent molecular characterizations of microbial communities from deep-sea hydrothermal sites indicate the predominance of bacteria belonging to the epsilon subdivision of Proteobacteria (epsilon Proteobacteria). Here, we report the first enrichments and characterizations of four epsilon Proteobacteria that are directly associated with Alvinella pompejana, a deep sea hydrothermal vent polychete, or with hydrothermal vent chimney samples. These novel bacteria were moderately thermophilic sulfur-reducing heterotrophs growing on formate as the energy and carbon source. In addition, two of them (Am-H and Ex-18.2) could grow on sulfur lithoautrotrophically using hydrogen as the electron donor. Optimal growth temperatures of the bacteria ranged from 41 to 45 degrees C. Phylogenetic analysis of the small-subunit ribosomal gene of the two heterotrophic bacteria demonstrated 95% similarity to Sulfurospirillum arcachonense, an epsilon Proteobacteria isolated from an oxidized marine surface sediment. The autotrophic bacteria grouped within a deeply branching clade of the epsilon Proteobacteria, to date composed only of uncultured bacteria detected in a sample from a hydrothermal vent along the mid-Atlantic ridge. A molecular survey of various hydrothermal vent environments demonstrated the presence of two of these bacteria (Am-N and Am-H) in more than one geographic location and habitat. These results suggest that certain epsilon Proteobacteria likely fill important niches in the environmental habitats of deep-sea hydrothermal vents, where they contribute to overall carbon and sulfur cycling at moderate thermophilic temperatures.

A quantitative relationship that demonstrates mercury methylation rates in marine sediments are based on the community composition and activity of sulfate-reducing bacteria.

A quantitative framework was developed which estimates mercury methylation rates (MMR) in sediment cores based on measured sulfate reduction rates (SRR) and the community composition sulfate-reducing bacterial consortia. MMR and SRR as well as group-specific 16S rRNA concentrations (as quantified by probe signal) associated with sulfate-reducing bacteria (SRB) were measured in triplicate cores of saltmarsh sediments. Utilizing previously documented conversion factors in conjunction with field observations of sulfate reduction, MMR were calculated, and the results were compared to experimentally derived measurements of MMR. Using our novel field data collected in saltmarsh sediment where sulfate reduction activity is high, calculated and independently measured MMR results were consistently within an order of magnitude and displayed similar trends with sediment depth. In an estuarine sediment where sulfate reduction activity was low, calculated and observed MMR diverged by greater than an order of magnitude, but again trends with depth were similar. We have expanded the small database generated to date on mercury methylation in sulfur-rich marine sediments. The quantitative frameworkwe have developed further elucidates the coupling of mercury methylation to sulfate reduction by basing calculated rates of mercury methylation on the activity and community composition of sulfate-reducing bacteria. The quantitative framework may also provide a promising alternative to the difficult and hazardous determination of MMR using radiolabeled mercury.

Fate of atrazine and alachlor in redox-treated ferruginous smectite.

The oxidation state of structural iron (Fe) in clay minerals exerts a large influence on clay surface chemistry and may affect the adsorption and degradation of pesticides in the environment. This effect, however, has been little investigated. In the present study, herbicides atrazine and alachlor were reacted with ferruginous smectite (sample SWa-1) in its oxidized, reduced (either chemically or bacterially), and reduced-reoxidized states. In some experiments the herbicide was labeled with 14C. Gas chromatography/mass spectrometry (GC-MS) was also used to detect alachlor degradation products. Compared to oxidized clays, reduction by both chemical and microbial treatments decreased the concentration of both herbicides in the surrounding solution. Reoxidized clay exhibited behavior similar to the oxidized clay. Hydrolysis-dechlorination of atrazine occurred in the presence of chemically reduced SWa-1, and GC-MS analysis of alachlor revealed at least 14 degradation products after treatment with reduced clay and only two with the oxidized clay. Interaction of atrazine and alachlor with the clay may be through a H bond with the waters of hydration surrounding interlayer cations, the extent of which should increase with increasing acidity; but under reduced conditions, the validity of this model is unclear. Reduction of structural Fe may affect pH-dependent phenomena in two ways: The increased surface charge density increases the number of hydrated interlayer cations, thereby enhancing surface acidity, and increased electron density at basal surface oxygens increases their Brønsted basicity. Atrazine could, therefore, adsorb and/or degrade through either acid or alkaline hydrolysis pathways. Increased reduction potential of the reduced clay surfaces may also promote degradation.

Sulfate-reducing bacteria methylate mercury at variable rates in pure culture and in marine sediments.

Differences in methylmercury (CH(3)Hg) production normalized to the sulfate reduction rate (SRR) in various species of sulfate-reducing bacteria (SRB) were quantified in pure cultures and in marine sediment slurries in order to determine if SRB strains which differ phylogenetically methylate mercury (Hg) at similar rates. Cultures representing five genera of the SRB (Desulfovibrio desulfuricans, Desulfobulbus propionicus, Desulfococcus multivorans, Desulfobacter sp. strain BG-8, and Desulfobacterium sp. strain BG-33) were grown in a strictly anoxic, minimal medium that received a dose of inorganic Hg 120 h after inoculation. The mercury methylation rates (MMR) normalized per cell were up to 3 orders of magnitude higher in pure cultures of members of SRB groups capable of acetate utilization (e.g., the family Desulfobacteriaceae) than in pure cultures of members of groups that are not able to use acetate (e.g., the family Desulfovibrionaceae). Little or no Hg methylation was observed in cultures of Desulfobacterium or Desulfovibrio strains in the absence of sulfate, indicating that Hg methylation was coupled to respiration in these strains. Mercury methylation, sulfate reduction, and the identities of sulfate-reducing bacteria in marine sediment slurries were also studied. Sulfate-reducing consortia were identified by using group-specific oligonucleotide probes that targeted the 16S rRNA molecule. Acetate-amended slurries, which were dominated by members of the Desulfobacterium and Desulfobacter groups, exhibited a pronounced ability to methylate Hg when the MMR were normalized to the SRR, while lactate-amended and control slurries had normalized MMR that were not statistically different. Collectively, the results of pure-culture and amended-sediment experiments suggest that members of the family Desulfobacteriaceae have a greater potential to methylate Hg than members of the family Desulfovibrionaceae have when the MMR are normalized to the SRR. Hg methylation potential may be related to genetic composition and/or carbon metabolism in the SRB. Furthermore, we found that in marine sediments that are rich in organic matter and dissolved sulfide rapid CH(3)Hg accumulation is coupled to rapid sulfate reduction. The observations described above have broad implications for understanding the control of CH(3)Hg formation and for developing remediation strategies for Hg-contaminated sediments.

Dissolution and reduction of magnetite by bacteria.

Magnetite (Fe3O4) is an iron oxide of mixed oxidation state [Fe(II), Fe(III)] that contributes largely to geomagnetism and plays a significant role in diagenesis in marine and freshwater sediments. Magnetic data are the primary evidence for ocean floor spreading and accurate interpretation of the sedimentary magnetic record depends on an understanding of the conditions under which magnetite is stable. Though chemical reduction of magnetite by dissolved sulfide is well known, biological reduction has not been considered likely based upon thermodynamic considerations. This study shows that marine and freshwater strains of the bacterium Shewanella putrefaciens are capable of the rapid dissolution and reduction of magnetite, converting millimolar amounts to soluble Fe(II)in a few days at room temperature. Conditions under which magnetite reduction is optimal (pH 5-6, 22-37 degrees C) are consistent with an enzymatic process and not with simple chemical reduction. Magnetite reduction requires viable cells and cell contact, and it appears to be coupled to electron transport and growth. In a minimal medium with formate or lactate as the electron donor, more than 10 times the amount of magnetite was reduced over no carbon controls. These data suggest that magnetite reduction is coupled to carbon metabolism in S. putrefaciens. Bacterial reduction rates of magnetite are of the same order of magnitude as those estimated for reduction by sulfide. If such remobilization of magnetite occurs in nature, it could have a major impact on sediment magnetism and diagenesis.

Localization of the binding site of an antibody affecting ATPase activity of chaperonin cpn60 from Bordetella pertussis.

Image processing has revealed the attachment site of antibody 54G8 on chaperonin 60 (cpn60) from Bordetella pertussis. This antibody, previously shown to affect the ability of chaperonin 10 (cpn10) to inhibit the ATPase activity of cpn60, is attached at the ends of the cpn60 and links the molecules into long chains. When only Fab fragments, which also affect ATPase activity, are used for labeling, these attach to both ends of the cpn60 molecule, but the long chains are not seen. Some perturbation of cpn60 was seen when Fab fragments were bound (Fab:cpn60 = 28:1).

Mediation of sulfur speciation by a black sea facultative anaerobe.

Shewanella putrefaciens, a respiratory facultative anaerobe isolated from the Black Sea, can reduce thiosulfate, sulfite, and elemental sulfur to sulfide readily and quantitatively. This widespread and anaerobically versatile microorganism, which is incapable of reducing sulfate, uses oxidized sulfur intermediates as electron acceptors during the respiratory oxidation of organic matter. Because of its widespread distribution and abundance, it may play a significant role in sulfur and trace metal cycling in the Black Sea and in other marine and freshwater anaerobic environments.

Immunochemical localization of a region of chaperonin-60 important for productive interaction with chaperonin-10.

An IgG1 monoclonal antibody (mAb 54G8) which binds to both Bordetella pertussis chaperonin-60 (cpn60) and Escherichia coli cpn60 (GroEL) was produced. mAb 54G8 as well as Fab fragments prepared from this antibody were found to abolish the ability of chaperonin-10 (cpn10, GroES) to inhibit the ATPase activity of both B. pertussis cpn60 and E. coli cpn60. Electron microscopy was used to localize the binding site of the monoclonal antibody on the B. pertussis cpn60 molecule. In the absence of the antibody, the B. pertussis molecule exhibited the tetradecameric structure typical of cpn60. Both end views (showing 7-fold symmetry of the face of the molecule) and side views were evident. When mAb 54G8 was bound, B. pertussis cpn60 molecules appeared to be cross-linked so that they formed long chains. Only side views of the molecules were seen in these long chains. When B. pertussis cpn60 complexed with Fab fragments of mAb 54G8 was examined, chains were no longer observed. Instead, side views of B. pertussis cpn60 were often seen with Fab fragments extending from the ends of the molecule. These data indicate that mAb 54G8 appears to bind at or near the end of the B. pertussis cpn60 molecule and that binding of mAb 54G8 at this location affects the ability of cpn10 to productively interact with cpn60, most likely either by sterically blocking the binding of cpn10, by affecting the conformation of cpn60 in such a way that it no longer binds cpn10, or by inhibiting proper transduction of the effects of cpn10 binding.

Purification and immunological characterization of a GroEL-like protein from Bordetella pertussis.

A GroEL-like protein from Bordetella pertussis was purified. This protein was found to have the tetradecameric subunit structure typical of the GroEL family of proteins and to contain epitopes similar to those of other members of this family, including a human GroEL-like protein. Active immunization of neonatal mice with the B. pertussis GroEL-like protein provided little protection against an aerosol challenge with B. pertussis. Antibodies to this protein were elicited in mice by a standard diphtheria-tetanus-pertussis (DTP) vaccine but not by an experimental acellular pertussis vaccine. Since the Bordetella GroEL-like protein was found to contain epitopes similar to those on the mammalian analog, the potential exists that vaccination with standard DTP vaccines may induce antibodies which react with the mammalian GroEL analog.

Purification and analysis of the antigenicity of a 69,000 Da protein from Bordetella pertussis.

A purification scheme was devised for a 69-kDa outer membrane protein of Bordetella pertussis, a virulence-associated protein which may play a role in the pathogenesis of the organism. The protein was purified to apparent homogeneity by heating B. pertussis cells for 1 h at 60 degrees C followed by DEAE-Sepharose and Affi-Gel Blue chromatography. Antibodies found in sera obtained from patients diagnosed as having pertussis reacted with this protein. This purification scheme should be useful for the production of the 69 kDa protein which is currently being evaluated as a pertussis vaccine candidate.