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We report a new synthesis of best estimates of the inputs of fixed nitrogen to the world ocean via atmospheric deposition and compare this to fluvial inputs and dinitrogen fixation. We evaluate the scale of human perturbation of these fluxes. Fluvial inputs dominate inputs to the continental shelf, and we estimate that about 75% of this fluvial nitrogen escapes from the shelf to the open ocean. Biological dinitrogen fixation is the main external source of nitrogen to the open ocean, i.e., beyond the continental shelf. Atmospheric deposition is the primary mechanism by which land‐based nitrogen inputs, and hence human perturbations of the nitrogen cycle, reach the open ocean. We estimate that anthropogenic inputs are currently leading to an increase in overall ocean carbon sequestration of ~0.4% (equivalent to an uptake of 0.15 Pg C yr−1and less than the Duce et al. (2008) estimate). The resulting reduction in climate change forcing from this ocean CO2uptake is offset to a small extent by an increase in ocean N2O emissions. We identify four important feedbacks in the ocean atmosphere nitrogen system that need to be better quantified to improve our understanding of the perturbation of ocean biogeochemistry by atmospheric nitrogen inputs. These feedbacks are recycling of (1) ammonia and (2) organic nitrogen from the ocean to the atmosphere and back, (3) the suppression of nitrogen fixation by increased nitrogen concentrations in surface waters from atmospheric deposition, and (4) increased loss of nitrogen from the ocean by denitrification due to increased productivity stimulated by atmospheric inputs. A new estimate of total atmospheric fixed nitrogen inputs to the ocean (39 Tg N yr−1) and its spatial distribution is presentedThe effects of atmospheric deposition on the oceans are estimated as an increase of productivity equivalent to 0.15 Pg C yr−1Four key uncertainties in these estimates are identified

Ocean deoxygenation threatens ocean productivity, carbon cycling and marine ecosystems. Shelf seas are highly dynamic regions, which contributes to their high productivity and also makes monitoring and constraining their oxygen status a challenge. Here, using the temperate Celtic shelf sea (April and July 2015) as a case study, we present high‐resolution ocean glider observations of turbulence and biogeochemical parameters, demonstrating the potential of these autonomous platforms for environmental monitoring. We estimate vertical turbulent oxygen fluxes be 25% higher in summer than in spring, due to the presence of subsurface chlorophyll and associated oxygen maxima at the seasonal thermocline. We demonstrate that glider‐based estimates were able to constrain similar bottom layer respiration rates as those derived from traditional ship‐based measurements. We suggest ocean gliders are useful monitoring tools that can aid sustainable management of shelf sea ecosystems. Oxygen levels in the ocean are decreasing. Oxygen is needed by almost all life in the oceans, thus low oxygen levels can result in dramatic changes to marine ecosystems. The decrease in oxygen levels is particularly alarming in the coastal ocean or “shelf sea” (the region between the land and the deep open ocean), which supports the majority of global fisheries (over 90%). Therefore, there is both an urgent societal and an environmental need to better understand processes influencing oxygen levels in the coastal ocean, such as physical water circulation and mixing, and biological oxygen production and consumption. Here we present turbulent mixing data collected over 40 days in a typical shelf sea using an unmanned, autonomous underwater vehicle (AUV) called an ocean glider. We use this data combined with oxygen data to calculate the contribution of physical oxygen fluxes to the observed change in oxygen, and from this deduce how much of the change was driven by biology. We prove that AUVs may be used as an effective method for monitoring oxygen dynamics and that this can aid responsible marine management in shelf seas. Glider observations are able to integrate physical and biogeochemical processes influencing oxygen depletion in shelf seasMixing and advection replenish respired oxygen in the bottom mixed layerThe presence of a subsurface oxygen maxima results in larger oxygen fluxes to the bottom mixed layer in summer compared to spring Glider observations are able to integrate physical and biogeochemical processes influencing oxygen depletion in shelf seas Mixing and advection replenish respired oxygen in the bottom mixed layer The presence of a subsurface oxygen maxima results in larger oxygen fluxes to the bottom mixed layer in summer compared to spring

Arsenate resistance is exhibited by the ericoid mycorrhizal fungus Hymenoscyphus ericae collected from As-contaminated mine soils. To investigate the mechanism of arsenate resistance, uptake kinetics for arsenate (H(2)AsO(4)(-)), arsenite (H(3)AsO(3)), and phosphate (H(2)PO(4)(-)) were determined in both arsenate-resistant and -non-resistant H. ericae. The uptake kinetics of H(2)AsO(4)(-), H(3)AsO(3), and H(2)PO(4)(-) in both resistant and non-resistant isolates were similar. The presence of 5.0 microM H(2)PO(4)(-) repressed uptake of H(2)AsO(4)(-) and exposure to 0.75 mM H(2)AsO(4)(-) repressed H(2)PO(4)(-) uptake in both H. ericae. Mine site H. ericae demonstrated an enhanced As efflux mechanism in comparison with non-resistant H. ericae and lost approximately 90% of preloaded cellular As (1-h uptake of 0.22 micromol g(-1) dry weight h(-1) H(2)AsO(4)(-)) over a 5-h period in comparison with non-resistant H. ericae, which lost 40% of their total absorbed H(2)AsO(4)(-). As lost from the fungal tissue was in the form of H(3)AsO(3). The results of the present study demonstrate an enhanced H(3)AsO(3) efflux system operating in mine site H. ericae as a mechanism for H(2)AsO(4)(-) resistance. The ecological significance of this mechanism of arsenate resistance is discussed.

The ability of an unidentified mycobiont from Pisonia grandis mycorrhizas to utilize organic nitrogen and phosphorus sources was determined in axenic liquid cultures. The fungus utilized inorganic phosphate and both freely- and poorly-soluble salts of inositol hexaphosphate as sole phosphorus sources. With the exception of uric acid which did not support growth, the yield of the mycobiont on all organic nitrogen sources tested was significantly greater than the yield on either NH4+ or NO3−. It is suggested that the major ecological role of the Pisonia mycobiont in stands of P. grandis on coral cays may be rapid absorption of allantoin and urea produced during degradation of uric acid by the soil microflora. This may be important in retaining nitrogen in the soil∶plant system prior to loss from the coral cay by further degradation, volatilization and/or leaching.

1. The effects of amiloride and frusemide on lithium clearance were studied during changes in dietary sodium chloride intake and during infusion of 0.9% NaCl in normal human volunteers. 2. Lithium and fractional lithium clearances were less on the low than on the high salt diet. Values for the medium salt diet were intermediate. Acute extracellular fluid volume expansion with 0.9% NaCl infusion and extracellular fluid volume contraction 3–4 h after intravenous frusemide caused lithium and fractional lithium clearances to increase and decrease respectively. 3. Amiloride caused small changes in lithium and fractional lithium clearances on a low salt diet, but was without effect when salt intake was medium or high. 4. Increases in lithium clearance occurred immediately after frusemide irrespective of dietary salt intake and in subjects infused with 0.9% NaCl. Only in salt-depleted subjects did frusemide cause a substantial increase in fractional lithium clearance. Changes induced under other circumstances were small. 5. It is concluded that the lithium clearance method for assessment of proximal tubule salt and water re-absorption can be used with some degree of confidence in certain circumstances (medium and high salt intake as well as in acute volume expansion) but may not be reliable when dietary salt intake is low.

Single isolates of a mycobiont isolated from Pisonia grandisR. Br., Pisolithus tinctorius(Pers.) Coker & Couch and Tylospora fibrillosa(Burt.) Donk were compared with regard to their relative abilities to produce key enzymes of inorganic nitrogen assimilation. Nitrate reductase (NR) activities in the P. grandismycobiont and T. fibrillosawere significantly lower than in P. tinctorius. While specific activities for glutamate dehydrogenase (GDH) were higher in P. tinctoriusthan the other two fungi following NH4+pre-treatment, glutamine synthetase (GS) activity did not differ significantly between the three fungi. In all three fungi, specific activities for GS were significantly higher than for GDH. NR activity was expressed in all three fungi regardless of the nitrogen source in the medium, but in P. tinctoriusdiminished following continued exposure to either NO3–, NH4+, glutamine or NO3–+ glutamine. The data are discussed in relation to nitrogen utilisation by the P. grandismycobiont.

Os autores procuram dar mais um contributo para a avaliação pré-operatória dos doentes com carcinoma de não pequenas células que vão ser sujeitos a cirurgia de ressecção pulmonar.

Abstract:  The internal transcribed spacer (ITS) region of a mycobiont isolated from Pisonia grandis R. Br. (Nyctaginaceae) was sequenced and a comparison made with sequences currently available in the GenBank Nucleotide Database. The mycobiont ITS sequence showed a high degree of homology (up to 87% over 637 bases) with a number of Thelephoraceae isolates, strongly implying that it belongs in that taxon. Published descriptions of hyphal morphology also show broad correlation between the P. grandis mycobiont and the Thelephoraceae isolates. The data highlight the usefulness of ITS sequence data in mycorrhizal research and the need for researchers to submit to the database ITS sequence data for mycorrhizal fungi with which they are working.