Effects of ultraviolet and visible radiation on the cellular concentrations of dimethylsulfoniopropionate (DMSP) in Emiliania huxleyi (strain L)

Emiliania huxleyi is an important component of the global carbon and sulfur cycles and is known to be sensitive to ultraviolet (UV) radiation. We investigated the influence of radiation intensity and of short-term exposure to UV radiation on the per-cell amount and intracellular concentration of dimethylsulfoniopropionate (DMSP). E. huxleyi (strain L) was exposed to artificial radiation intensities similar to those at 15 in (700 mumol PAR [photosynthetically active radiation] m(-2) s(-1)) and 25 in depth (400 mumol PAR m(-2) s(-1)) in the subtropical Atlantic Ocean. Exposure to UV radiation led to a 10 to 25% increase in the per-cell amount of DMSP as compared to E. huxleyi exposed to only PAR, whereas photosynthetic activity (measured via oxygen production) of UV-exposed E. huxleyi was reduced by 18 to 22%. Furthermore, the intracellular DMSP concentration was always higher in PAR + UV-exposed E. huxleyi than in PAR-exposed E. huxleyi, despite the small but significant increase in cell volume of E. huxleyi after exposure to PAR + UV as compared to PAR exposure only. A shift of the radiation conditions to higher levels resulted in a short-term increase in the per-cell amount and intracellular concentration of DMSP. E. huxleyi cultured in turbidostats under different radiation intensities (ranging from 5.6 to 400 mumol PAR m(-2) s(-1)) revealed a significant monotonical increase in the per-cell amount and the intracellular concentration of DMSP with increasing radiation intensity

Comparison of Deep-Water Viromes from the Atlantic Ocean and the Mediterranean Sea

The aim of this study was to compare the composition of two deep-sea viral communities obtained from the RomancheFracture Zone in the Atlantic Ocean (collected at 5200 m depth) and the southwest Mediterranean Sea (from 2400 m depth)using a pyro-sequencing approach. The results are based on 18.7% and 6.9% of the sequences obtained from the AtlanticOcean and the Mediterranean Sea, respectively, with hits to genomes in the non-redundant viral RefSeq database. Theidentifiable richness and relative abundance in both viromes were dominated by archaeal and bacterial viruses accountingfor 92.3% of the relative abundance in the Atlantic Ocean and for 83.6% in the Mediterranean Sea. Despite characteristicdifferences in hydrographic features between the sampling sites in the Atlantic Ocean and the Mediterranean Sea, 440 virusgenomes were found in both viromes. An additional 431 virus genomes were identified in the Atlantic Ocean and 75 virusgenomes were only found in the Mediterranean Sea. The results indicate that the rather contrasting deep-sea environmentsof the Atlantic Ocean and the Mediterranean Sea share a common core set of virus types constituting the majority of bothvirus communities in terms of relative abundance (Atlantic Ocean: 81.4%; Mediterranean Sea: 88.7%)

土地家屋調査士のための法律学（1） : 土地家屋調査士の業務

１連載開始に際して　　２「弁護士」型業務の獲得　　３認定土地家屋調査士　　４調査士志望者の減

Fracture zones in the Mid Atlantic Ridge lead to alterations in prokaryotic and viral parameters in deep-water masses

We hypothesized that mixing zones of deep-water masses act as ecotones leading to alterations in microbial diversity and activity due to changes in the biogeochemical characteristics of these boundary systems. We determined the changes in prokaryotic and viral abundance and production in the Vema Fracture Zone (VFZ) of the subtropical North Atlantic Ocean, where North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW) are funneled through this narrow canyon and therefore, are subjected to intense vertical mixing. Consequently, salinity, potential temperature, oxygen, PO4, SiO4, NO3 were altered in the NADW inside the VFZ as compared to the NADW outside of the VFZ. Also, viral abundance, lytic viral production (VP) and the virus-to-prokaryote ratio (VPR) were elevated in the NADW in the VFZ as compared to the NADW outside the VFZ. In contrast to lytic VP, lysogenic VP and both the frequency of lytically (FIC) and lysogenically infected cells (FLC) did not significantly differ between in- and outside the VFZ. Generally, FIC was higher than FLC throughout the water column. Prokaryotic (determined by T-RFLP) and viral (determined by RAPD-PCR) community composition was depth-stratified inside and outside the VFZ. The viral community was more modified both with depth and over distance inside the VFZ as compared to the northern section and to the prokaryotic communities. However, no clusters of prokaryotic and viral communities characteristic for the VFZ were identified. Based on our observations, we conclude that turbulent mixing of the deep water masses impacts not only the physico-chemical parameters of the mixing zone but also the interaction between viruses and prokaryotes due to a stimulation of the overall activity. However, only minor effects of deep water mixing were observed on the community composition of the dominant prokaryotes and viruses

Lower prokaryotic leucine incorporation rates under in situ pressure than under decompressed conditions in the deep north Atlantic

Comunicación oralProkaryotic activity and community composition is highly depth-stratified in the oceanic water column reflecting the increasing recalcitrance of dissolved organic matter and decreasing temperature with depth. The role of increasing hydrostatic pressure in controlling deep ocean microbial activity is less well-studied. To determine the influence in hydrostatic pressure on heterotrophic microbial activity, an in situ incubator was deployed in the North Atlantic Ocean at a depth between 500 to 2000 m. The in situ incubator was programmed to collect and incubate prokaryotes under the water after adding 3H-leucine and to fix a certain volume of the incubated samples at specific time intervals (3 to 10 h depending on the depth). Prokaryotic leucine incorporation obtained under in situ pressure conditions was generally lower than that on decompressed samples incubated on board. Ratios of in situ prokaryotic leucine incorporation to decompressed conditions decreased with increasing depth. Our results suggest that bulk heterotrophic prokaryotic production in the deep sea might be lower than expected

Dissolved inorganic carbon fixation of Thaumarchaeota vs. Bacteria in the meso- and upper bathypelagic waters of the world’s oceans differentiated with the use of metabolic inhibitors

Recent studies suggest that the dark ocean prokaryotes fix inorganic carbon at rates substantially higher than assumed. We have studied the contribution of Archaea vs. Bacteria to total prokaryotic fixation of dissolved inorganic carbon (DIC) in the meso- and upper bathypelagic waters of the world’s oceans during the Malaspina circumnavigation expedition carried out between December 2010 and July 2011. We used the metabolic inhibitor Erythromycin, an antibiotic specifically inhibiting growth of Bacteria but not affecting Archaea. Bacteria dominated throughout the water column in the three major ocean basins (54% of the total DAPI counts), decreasing in their relative contribution to total prokaryotic abundance from the surface to the meso- and bathypelagic waters. By contrast, the relative contribution of Thaumarchaeota was generally higher in the meso- and bathypelagic layers than in the surface waters (up to 29% of the total DAPI counts in the Pacific Ocean). Averaged over the entire water column, Thaumarchaeota contributed 8%, 33% and 18% to the total prokaryotic DIC fixation in the Indian, Pacific and Atlantic Ocean, respectively. The contribution of Thaumarchaeota to total prokaryotic DIC fixation increased with depth, particularly in the Atlantic below 1000 m depth and in the lower mesopelagic zone of the Pacific Ocean. Preliminary results from an station in the Atlantic Ocean, combining microautoradiography and fluorescence in situ hybridization (MICRO-CARD-FISH), confirmed that both Thaumarchaeota and some bacterial groups such as SAR 324 take up DIC. Thaumarchaeota and SAR 324 accounted for 7 % and 12% of DIC-positive DAPI-stained cells, respectively, as revealed by MICRO-CARD-FISH. Our results suggest that some phylogenetic groups may be significant contributors to the dark ocean chemoautotrophy

Taurine: an energy "drink" for deep sea microbes

Presentación oralThe wide use of –omics approaches has led to the discovery of novel metabolic pathways in uncultivated marine bacteria. For example, metagenomic and –proteomic studies revealed that taurine might be an important substrate for heterotrophic marine bacteria. Taurine, an organic acid, is widely produced by marine metazoans and some phytoplankton albeit its concentration and turnover in the ocean has not been determined yet. In this study, we determined the role of taurine as carbon and energy source throughout the water column of the open North Atlantic from the epipelagic to the bathypelagic realm. Bulk uptake and respiration of taurine were measured and microautoradiography was combined with catalyzed reporter deposition fluorescence in situ hybridization to evaluate taurine uptake by specific phylogenetic groups. A shift between the dominant use of taurine as a carbon source from the epi- and mesopelagic (about 40% of taurine respired) to the bathypelagic (76% respired) realm was observed. Taken together, our results indicate that taurine is effectively used by marine prokaryotes, especially in the mesopelagic environment where zooplankton, a potential source for taurine, reside during the day

Evidence for surface organic matter modulation of air-sea CO2 gas exchange

Air-sea CO2 exchange depends on the air-sea CO2 gradient and the gas transfer velocity (k), computed as a function of wind speed. Large discrepancies among relationships predicting k from wind suggest that other processes also contribute significantly to modulate CO2 exchange. Here we report, on the basis of the relationship between the measured gas transfer velocity and the organic carbon concentration at the ocean surface, a significant role of surface organic matter in suppressing air-sea gas exchange, at low and intermediate winds, in the open ocean, confirming previous observations. The potential role of total surface organic matter concentration (TOC) on gas transfer velocity (k) was evaluated by direct measurements of air-sea CO2 fluxes at different wind speeds and locations in the open ocean. According to the results obtained, high surface organic matter contents may lead to lower air-sea CO2 fluxes, for a given air-sea CO2 partial pressure gradient and wind speed below 5 m s−1, compared to that observed at low organic matter contents. We found the bias in calculated gas fluxes resulting from neglecting TOC to co-vary geographically and seasonally with marine productivity. These results support previous evidences that consideration of the role of organic matter in modulating air-sea CO2 exchange may improve flux estimates and help avoid possible bias associated to variability in surface organic concentration across the ocean

Схиигумен Сергий как маргинальная языковая личность в пространстве религиозно-политической коммуникации

SummaryThaumarchaeota are globally distributed and abundantmicroorganisms occurring in diverse habitats and thusrepresent a major source of archaeal lipids. The scopeof lipids as taxonomic markers in microbial ecologicalstudies is limited by the scarcity of comparative dataon the membrane lipid composition of cultivated representatives,including the phylum Thaumarchaeota.Here, we comprehensively describe the core and intactpolar lipid (IPL) inventory of ten ammonia-oxidisingthaumarchaeal cultures representing all four characterizedphylogenetic clades. IPLs of these thaumarchaealstrains are generally similar and consist of membranespanning,glycerol dibiphytanyl glycerol tetraetherswith monoglycosyl, diglycosyl, phosphohexose andhexose-phosphohexose headgroups. However, the relativeabundances of these IPLs and their core lipidcompositions differ systematically between the phylogeneticsubgroups, indicating high potential forchemotaxonomic distinction of thaumarchaeal clades.Comparative lipidomic analyses of 19 euryarchaeal andcrenarchaeal strains suggested that the lipid methoxyarchaeol is synthesized exclusively by Thaumarchaeotaand may thus represent a diagnostic lipidbiomarker for this phylum. The unprecedented diversityof the thaumarchaeal lipidome with 118 differentlipids suggests that membrane lipid composition andadaptation mechanisms in Thaumarchaeota are morecomplex than previously thought and include uniquelipids with as yet unresolved properties