A DFT study on the second-order nonlinear optical properties of the plenary mixed-metal polyoxometalate

The redox and second-order nonlinear optical (NLO) properties of organic–inorganic hybrid polyoxoanions [LNbOEMe₃]^3 ? , [LNbOEPh₃]^3 ?  (L = α-{PW₁₁O₃₉}^7 ? , E = Si, Ge, Sn, Pb) are investigated by density functional theory method. The element substitution effects on the molecular nonlinear response have been analysed. The results show that the computed β₀ values depend on both E (E = Si < Ge < Sn < Pb) and the organic groups connected with E. For [LNbOEPh₃]^3 ?  (L = α-{PW₁₁O₃₉}^7 ? , E = Si, Ge, Sn, Pb), the analysis of major contributions to β₀ value suggests that the charge transfer from organic group to Keggin polyanion plays the key role in NLO response; the polyanion acts as a donor, whereas the organic group acts as an acceptor in [LNbOEPh₃]^3 ? . Our results show that this kind of organic–inorganic hybrid compound possesses larger molecular second-order polarisability and might be a potential NLO material.     

15α-Hydroxylation of a steroid (13-ethyl-gon-4-en-3,17-dione) by Penicillium raistrickii in an ionic liquid/aqueous biphasic system

Biphasic processes are used in whole-cell biotransformation to overcome the low water solubility of substrates and products as well as their inhibitory effects on the biocatalyst. Commercially available [NTf₂]- and [PF₆]-based ionic liquids (ILs) were used in a biphasic system for the 15α-hydroxylation of 13-ethyl-gon-4-en-3,17-dione by Penicillium raistrickii. With the substrate at 5 g l^?1 and a volume ratio of IL to buffer, buffer pH and cell density at, 1:9, 6.5, 16.8 g_DW l^?1, respectively, the 15α-hydroxylation of 13-ethyl-gon-4-en-3,17-dione was achieved with a yield of 70 % after 72 h using [BMIm][NTf₂] in a 50 ml biphasic system. This is compared to a 30 % yield in a monophasic aqueous system. This suggests the potential industrial application of ILs-based biphasic systems for steroid biotransformation.     

Impacts of terminal (4R)-fluoroproline and (4S)-fluoroproline residues on polyproline conformation

Many interests have been focused on prolyl cis–trans isomerization which is related to protein folding and isomer-specific biochemical recognition. Since polyproline can adopt either type I (PPI) helices with all cis amide bonds or type II (PPII) helices with all trans amide bonds, it has been a valuable model to study the prolyl isomerization. Recent studies have shown that stereoelectronic effects govern the stability of PPII structure and the rate of PPII → PPI conversion. To further explore the terminal stereoelectronic effects on polyproline conformation, herein we synthesized a series of host–guest peptides in which (2S,4S)-4-fluoroproline (flp) or (2S,4R)-4-fluoroproline (Flp) residues are incorporated into the C- or N-terminal end of a peptide and studied the thermodynamic and kinetic consequences on polyproline conformation. Circular dichroism measurements revealed that inserting 4-fluoroproline residues into the C terminus of a polyproline peptide induces a great stereoelectronic effect on PPII stability and PPII → PPI conversion rates. From the C terminus, a (Flp)₃ triplet stabilizes PPII structure and increases the transition barrier of PPII → PPI conversion by 1.53 kJ mol^?1 while a (flp)₃ triplet destabilizes PPII conformation and reduce the PPII → PPI transition barrier by 4.61 kJ mol^?1. In contrast, the 4-fluoroproline substitutions at the N terminus do not exhibit distinct stereoelectronic effects on PPII stability and PPII → PPI conversion rates. Our data demonstrate that the C-terminal stereoelectronic effects have a more dramatic impact on PPII stability and PPII → PPI conversion kinetics.     

Anion–π interactions: CP-corrected vs. standard optimisation,AIM and NBO analyses

The anion–π interactions between Br^? , Cl^? , F^?  and H^?  anions and hexafluorobenzene (HFB), 1,2,4,5-tetracyanobenzene (TCB) and tetracyanopyrazine (TCP) have been studied by standard and counterpoise (CP) corrected methods at HF, B3LYP and MP2/6-31+ + G (d,p) levels of theory. The complexation energies were corrected for basis set superposition error (ΔE _BSSE) and zero point energy (ΔE _BSSE + ZPE). Also, the B3LYP results were corrected by single-point calculation at B3LYP/aug-cc-PVTZ level of theory. Although the CP-corrected method results in higher distances between anions and rings, the standard method gives lower complexation energies. TCP…X^?  series gives higher complexation energies in both CP-corrected and standard methods. Topological analysis of the charge density ρ(r) has been performed by the means of atoms in molecules method on the wave functions obtained at MP2/6-31+ + G (d,p) level of theory. The number and the nature of critical points depend on aromatic ring and anion. Natural bond orbital analysis indicates that n_X → π*_CC and n_X → π*_CN interactions are the most important interactions for TCB (and HFB)…X^?  and TCP…X^?  complexes, respectively.     

Induced change in <Emphasis Type="Italic">Arthrospira</Emphasis> sp. (<Emphasis Type="Italic">Spirulina</Emphasis>) intracellular and extracellular metabolites using multifactor stress combination approach

The interactive effects of light intensity, NaCl, nitrogen, and phosphorus on intracellular biomass content and extracellular polymeric substance production were assessed for Arthrospira sp. (Spirulina) in a two-phase culture process using principal component analysis and central composite face design. Under high light intensity (120 μmol photons m^?2?s^?1) and low NaCl (1 gL^?1), NaNO₃, and K₂HPO₄ (0.5 g L^?1), the carbohydrate content was maximized to 26.61%. Interaction of both K₂HPO₄ (1.6 gL^?1) and NaCl (1.19 gL^?1) with low NaNO₃ (0.5 gL^?1) achieved the maximum content of lipids (15.62%), while high NaCl (40 gL^?1), K₂HPO₄, and NaNO₃ (4.5 gL^?1) enhanced mainly total carotenoids (0.85%). Conversely, under low light intensity of 10 μmol photons m^?2?s^?1 combined with 11.76 gL^?1 of NaCl, 0.5 gL^?1 of NaNO₃, and 2.68 gL^?1 of K₂HPO₄, the phycobiliprotein content reached its highest level (16.09%). The maximum extracellular polymeric substance (EPS) production (0.902 gg^?1?DW) was triggered under moderate light of 57.25 μmol photons m^?2?s^?1 and interaction of high NaCl (40 gL^?1) and K₂HPO₄ (4.5 gL^?1) with low NaNO₃ (0.5 gL^?1). The maximization ratios of intracellular biomass content in terms of carbohydrate, lipid, total carotenoid, phycobiliprotein, and EPS production were 3.55-, 1.73-, 9.55-, 2.92-, and 1.46-fold, respectively, greater than those obtained at optimal growth conditions. This study demonstrated that the multiple stress factors applied to the adopted two-phase culture process could be a promising strategy to produce biomass enriched in various high-value compound.     

Biosynthesis of the carbohydrate moieties of arabinogalactan proteins by membrane-bound β-glucuronosyltransferases from radish primary roots

A membrane fraction from etiolated 6-day-old primary radish roots (Raphanus sativus L. var hortensis) contained β-glucuronosyltransferases (GlcATs) involved in the synthesis of the carbohydrate moieties of arabinogalactan proteins (AGPs). The GlcATs transferred [¹⁴C]GlcA from UDP-[¹⁴C]GlcA on to β-(1 → 3)-galactan as an exogenous acceptor substrate, giving a specific activity of 50–150 pmol min^?1 (mg protein)^?1. The enzyme specimen also catalyzed the transfer of [¹⁴C]GlcA on to an enzymatically modified AGP from mature radish root. Analysis of the transfer products revealed that the transfer of [¹⁴C]GlcA occurred preferentially on to consecutive (1 → 3)-linked β-Gal chains as well as single branched β-(1 → 6)-Gal residues through β-(1 → 6) linkages, producing branched acidic side chains. The enzymes also transferred [¹⁴C]GlcA residues on to several oligosaccharides, such as β-(1 → 6)- and β-(1 → 3)-galactotrioses. A trisaccharide, α-l-Araf-(1 → 3)-β-Gal-(1 → 6)-Gal, was a good acceptor, yielding a branched tetrasaccharide, α-l-Araf-(1 → 3)[β-GlcA-(1 → 6)]-β-Gal-(1 → 6)-Gal. We report the first in vitro assay system for β-GlcATs involved in the AG synthesis as a step toward full characterization and cloning.     

Theoretical description of the magnetic properties of μ3-hydroxo bridged trinuclear copper(II) complexes

A theoretical study of the magnetic properties, using density functional theory, of a family of trinuclear μ₃-OH copper(II) complexes reported in the literature is presented. The reported X-ray crystal structures of [Cu₃(μ₃-OH)(aat)₃(H₂O)₃](NO₃)₂·H₂O (HUKDUM), where aat: 3-acetylamine-1,2,4-triazole; [Cu₃(μ₃-OH)(aaat)₃(H₂SO₄)(HSO₄)(H₂O)] (HUKDOG), where aaat: 3-acetylamine-5-amine-1,2,4-triazole; [Cu₃(μ₃-OH)(PhPyCNO)₃(tchlphac)₂] (HOHQUR), where PhPyCNO: phenyl 2-pyridyl-ketoxime and tchlphac: acid 2,4,5-trichlorophenoxyacetic; [Cu₃(μ₃-OH)(PhPyCNO)₃(NO₃)₂(CH₃OH)] (ILEGEM); [Cu₃(μ₃-OH)(pz)₃(Hpz)₃(ClO₄)₂] (QOPJIP), where Hpz?=?pyrazole; [Cu₃(μ₃-OH)(pz)₃(Hpz)(Me₃CCOO)₂]?2Me₃CCOOH (DEFSEN) and [Cu₃(μ₃-OH)(8-amino-4-methyl-5-azaoct-3-en-2-one)₃][CuI₃] (RITXUO), were used in the calculations. The magnetic exchange constants were calculated using the broken-symmetry approach. The calculated J values are for HUKDUM J₁?=??68.6 cm^?1, J₂?=??69.9 cm^?1, J₃?=??70.4 cm^?1; for HUKDOG, J₁?=??73.5 cm^?1, J₂?=??58.9 cm^?1, J₃?=??62.1 cm^?1; for HOHQUR J₁?=??128.3 cm^?1, J₂?=??134.1 cm^?1, J₃?=??120.4 cm^?1; for ILEGEM J₁?=??151.6 cm^?1, J₂?=??173.9 cm^?1, J₃?=??186.9 cm^?1; for QOPJIP J₁?=??118.3 cm^?1, J₂?=??106.0 cm^?1, J₃?=??120.6 cm^?1; for DEFSEN J₁?=??74.9 cm^?1, J₂?=??64.0 cm^?1, J₃?=??57.7 cm^?1 and for RITXUO J₁?=??10.9 cm^?1, J₂?=?+14.3 cm^?1, J₃?=??35.4 cm^?1. The Kahn-Briat model was used to correlate the calculated magnetic properties with the overlap of the magnetic orbitals. Spin density surfaces show that the delocalization mechanism is predominant in all the studied compounds.

Electrochemical selective detection of dopamine on microbial carbohydrate-doped multiwall carbon nanotube-modified electrodes

Microbial carbohydrate-doped multiwall carbon nanotube (MWNT)-modified electrodes were prepared for the purpose of determining if 4-(2-aminoethyl)benzene-1,2-diol (3,4-dihydroxyphenylalanine; dopamine) exists in the presence of 0.5 mM ascorbic acid, a representative interfering agent in neurotransmitter detection. The microbial carbohydrate dopants were α-cyclosophorohexadecaose (α-C16) from Xanthomonas oryzae and cyclic-(1 → 2)-β-d-glucan (Cys) from Rhizobium meliloti. The cyclic voltammetric responses showed that the highest sensitivity (5.8 × 10^?3 mA cm^?2 μM^?1) is attained with the Cys-doped MWNT-modified ultra-trace carbon electrode, and that the α-C16-doped MWNT-modified glassy carbon electrode displays the best selectivity to dopamine (the approximate peak potential separation is 310 mV).     

Integrated effects of organic,inorganic and biological amendments on methane emission,soil quality and rice productivity in irrigated paddy ecosystem of Bangladesh: field study of two consecutive rice growing seasons

Aims

Effects of different soil amendments were investigated on methane (CH₄) emission, soil quality parameters and rice productivity in irrigated paddy field of Bangladesh.

Methods

The experiment was laid out in a randomized complete block design with five treatments and three replications. The experimental treatments were urea (220 kg ha^?1) + rice straw compost (2 t ha^?1) as a control, urea (170 kg ha^?1) + rice straw compost (2 t ha^?1) + silicate fertilizer, urea (170 kg ha^?1) + sesbania biomass (2 t ha^?1 ) + silicate fertilizer, urea (170 kg ha^?1) + azolla biomass (2 t ha^?1) + cyanobacterial mixture 15 kg ha^?1 silicate fertilizer, urea (170 kg ha^?1) + cattle manure compost (2 t ha^?1) + silicate fertilizer.

Results

The average of two growing seasons CH₄ flux 132 kg ha^?1 was recorded from the conventional urea (220 kg ha^?1) with rice straw compost incorporated field plot followed by 126.7 (4 % reduction), 130.7 (1.5 % reduction), 116 (12 % reduction) and 126 (5 % reduction) kg CH₄ flux ha^?1 respectively, with rice straw compost, sesbania biomass, azolla anabaena and cattle manure compost in combination urea and silicate fertilizer applied plots. Rice grain yield was increased by 15 % and 10 % over the control (4.95 Mg ha^?1) with silicate plus composted cattle manure and silicate plus azolla anabaena, respectively. Soil quality parameters such as soil organic carbon, total nitrogen, microbial biomass carbon, soil redox status and cations exchange capacity were improved with the added organic materials and azolla biofertilizer amendments with silicate slag and optimum urea application (170 kg ha^?1) in paddy field.

Conclusion

Integrated application of silicate fertilizer, well composted organic manures and azolla biofertilizer could be an effective strategy to minimize the use of conventional urea fertilizer, reducing CH₄ emissions, improving soil quality parameters and increasing rice productivity in subtropical countries like Bangladesh.     

Fate of radiocesium in freshwater aquatic plants and algae in the vicinity of the Fukushima Daiichi nuclear power plant

The behavior of radiocesium (¹³⁷Cs) in aquatic plants (five species) and algae (three genera) grown in either a river (one sampling point) or pond (four sampling points) in the vicinity of the Fukushima Daiichi nuclear power plant was investigated. The ¹³⁷Cs concentration of <0.45-μm fractions of water taken from the river and ponds was between 5.01 × 10^?1 and 2.98 Bq/L, while that of sediment was between 4.85 × 10³ and 5.72 × 10⁴ Bq/kg dry weight. The ratio of ¹³⁷Cs concentration of sediment/water in ponds was ~10⁴. The sediment-to-plant transfer factor (TF) [(¹³⁷Cs concentration Bq/kg dry weight_plant) × (¹³⁷Cs concentration Bq/kg dry weight_sediment)^?1] was also measured. For aquatic plants, the highest value was 5.55 for Potamogeton crispus from the river, while the lowest was 3.34 × 10^?2 for P. distinctus from a pond. There were significant differences in values between aquatic plants belonging to the same genus. The water-to-plant TF [(¹³⁷Cs concentration Bq/kg dry weight_plant) × (¹³⁷Cs concentration Bq/L_water)^?1] of filamentous algae (Spirogyra sp.) and cyanobacteria (coexisting Anabaena sp. and Microcystis sp.) were 2.39 × 10³ and 1.26 × 10³, respectively. The ¹³⁷Cs concentration of cyanobacteria in pond water was 4.87 × 10^?1 Bq/L, which was the same order of magnitude as the ¹³⁷Cs concentration of pond water. Enrichment of ¹³⁷Cs in cyanobacteria was not observed.     

Seasonal and spatial variations of methane emissions from coastal marshes in the northern Yellow River estuary, China

Aims and methods

To evaluate the seasonal and spatial variations of methane (CH₄) emissions and understand the controlling factors, we measured CH₄ fluxes and their environmental variables for the first time by a static chamber technique in high Suaeda salsa marsh (HSM), middle S. salsa marsh (MSM), low S. salsa marsh (LSM) and bare flat (BF) in the northern Yellow River estuary throughout a year.

Results

CH₄ emissions from coastal marsh varied throughout different times of the day and significant differences were observed in some sampling periods (p?<?0.05). Over all sampling periods, CH₄ fluxes averaged between ?0.392 mgCH₄ m^?2?h^?1 and 0.495 mgCH₄ m^?2?h^?1, and emissions occurred during spring (0.008 mgCH₄ m^?2?h^?1) and autumn (0.068 mgCH₄ m^?2?h^?1) while sinks were observed during summer (?0.110 mgCH₄ m^?2?h^?1) and winter (?0.009 mgCH₄ m^?2?h^?1). CH₄ fluxes from the four marshes were not significantly different (p?>?0.05), and emissions occurred in LSM (0.026 mgCH₄ m^?2?h^?1) and BF (0.055 mgCH₄ m^?2?h^?1) while sinks were observed in HSM (?0.035 mgCH₄ m^?2?h^?1) and MSM (?0.022 mgCH₄ m^?2?h^?1). The annual average CH₄ flux from the intertidal zone was 0.002 mgCH₄ m^?2?h^?1, indicating that coastal marsh acted as a weak CH₄ source. Temporal variations of CH₄ emission were related to the interactions of abiotic factors (temperatures, soil moisture and salinity) and the variations of limited C and mineral N in sediments, while spatial variations were mainly affected by the vegetation composition at spatial scale.

Conclusions

This study observed a large spatial variation of CH₄ fluxes across the coastal marsh of the Yellow River estuary (CV?=?7856.25 %), suggesting that the need to increase the spatial replicates at fine scales before the regional CH₄ budget was evaluated precisely. With increasing exogenous nitrogen loading to the Yellow River estuary, the magnitude of CH₄ emission might be enhanced, which should also be paid more attentions as the annual CH₄ inventory was assessed accurately.     

A saponin isolated from <Emphasis Type="Italic">Agapanthus africanus</Emphasis> differentially induces apoplastic peroxidase activity in wheat and displays fungicidal properties

A spirostane with an attached trisaccharide, (25R)-5α-spirostane-2α,3β,5α-triol 3-O-(O-α-l-rhamnopyranosyl-(1 → 2)-O-(β-d-galactopyranosyl-(1 → 3))-β-d-glucopyranoside), was isolated and identified from the aerial parts of Agapanthus africanus by activity-guided fractionation. Fungicidal properties of the crude extract, semi-purified fractions as well as the purified active saponin from A. africanus were screened in vitro against Fusarium oxysporum. At a concentration of 1 mg mL^?1, the crude extract and semi-purified ethyl acetate and dichloromethane fractions showed significant antifungal activity. The purified saponin inhibited the in vitro mycelial growth of F. oxysporum completely (100 %) at a concentration of 125 µg mL^?1. Furthermore, to verify previously observed induced resistance by crude extracts of A. africanus towards leaf rust, intercellular PR-protein activity was determined in wheat seedlings following foliar application of the purified saponin at 100 µg mL^?1. In vitro peroxidase enzyme activity increased significantly (60 %) in wheat seedlings 48 h after treatment with the purified saponin, demonstrating its role as an elicitor to activate a defence reaction in wheat.     

Oligonucleotides Incorporating 7-(Aminoalkyn-1-yl)-7-deaza-2′-deoxyguanosines: Duplex Stability and Phosphodiester Hydrolysis by Exonucleases

Abstract

Self-complementary {[5′-d(G-C)₄]₂} and non-selfcomplementary oligonucleotides [5′-d(TAG GTC AAT ACT) ? 3′-d(ATC CAG TTA TGA)] containing 7-(ω-aminoalkyn-1-yl)-7-deaza-2′-deoxyguanosines (1a–c) (1) and 7-deaza-2′-deoxyguanosine instead of dG were studied regarding their thermal stability as well as their phosphodiester hydrolysis by either 3′ → 5′- or 5′ → 3′ – phosphodi esterase studied by MALDI-TOF MS.     

Multi-scale measurements and modeling of denitrification in streams with varying flow and nitrate concentration in the upper Mississippi River basin, USA

Denitrification is an important net sink for NO₃ ^? in streams, but direct measurements are limited and in situ controlling factors are not well known. We measured denitrification at multiple scales over a range of flow conditions and NO₃ ^? concentrations in streams draining agricultural land in the upper Mississippi River basin. Comparisons of reach-scale measurements (in-stream mass transport and tracer tests) with local-scale in situ measurements (pore-water profiles, benthic chambers) and laboratory data (sediment core microcosms) gave evidence for heterogeneity in factors affecting benthic denitrification both temporally (e.g., seasonal variation in NO₃ ^? concentrations and loads, flood-related disruption and re-growth of benthic communities and organic deposits) and spatially (e.g., local stream morphology and sediment characteristics). When expressed as vertical denitrification flux per unit area of streambed (U _denit, in μmol N m^?2 h^?1), results of different methods for a given set of conditions commonly were in agreement within a factor of 2–3. At approximately constant temperature (~20 ± 4°C) and with minimal benthic disturbance, our aggregated data indicated an overall positive relation between U _denit (~0–4,000 μmol N m^?2 h^?1) and stream NO₃ ^? concentration (~20–1,100 μmol L^?1) representing seasonal variation from spring high flow (high NO₃ ^?) to late summer low flow (low NO₃ ^?). The temporal dependence of U _denit on NO₃ ^? was less than first-order and could be described about equally well with power-law or saturation equations (e.g., for the unweighted dataset, U _denit ≈26 * [NO₃ ^?]^0.44 or U _denit ≈640 * [NO₃ ^?]/[180 + NO₃ ^?]; for a partially weighted dataset, U _denit ≈14 * [NO₃ ^?]^0.54 or U _denit ≈700 * [NO₃ ^?]/[320 + NO₃ ^?]). Similar parameters were derived from a recent spatial comparison of stream denitrification extending to lower NO₃ ^? concentrations (LINX2), and from the combined dataset from both studies over 3 orders of magnitude in NO₃ ^? concentration. Hypothetical models based on our results illustrate: (1) U _denit was inversely related to denitrification rate constant (k1_denit, in day^?1) and vertical transfer velocity (v _f,denit, in m day^?1) at seasonal and possibly event time scales; (2) although k1_denit was relatively large at low flow (low NO₃ ^?), its impact on annual loads was relatively small because higher concentrations and loads at high flow were not fully compensated by increases in U _denit; and (3) although NO₃ ^? assimilation and denitrification were linked through production of organic reactants, rates of NO₃ ^? loss by these processes may have been partially decoupled by changes in flow and sediment transport. Whereas k1_denit and v _f,denit are linked implicitly with stream depth, NO₃ ^? concentration, and(or) NO₃ ^? load, estimates of U _denit may be related more directly to field factors (including NO₃ ^? concentration) affecting denitrification rates in benthic sediments. Regional regressions and simulations of benthic denitrification in stream networks might be improved by including a non-linear relation between U _denit and stream NO₃ ^? concentration and accounting for temporal variation.     

Isolation and characterization of novel ginsenoside-hydrolyzing glycosidase from Microbacterium esteraromaticum that transforms ginsenoside Rb2 to rare ginsenoside 20(S)-Rg3

Ginsenoside Rb2 was transformed by recombinant glycosidase (Bgp2) into ginsenosides Rd and 20(S)-Rg3. The bgp2 gene consists of 2,430 bp that encode 809 amino acids, and this gene has homology to the glycosyl hydrolase family 2 protein domain. SDS-PAGE was used to determine that the molecular mass of purified Bgp2 was 87 kDa. Using 0.1 mg ml^?1 of enzyme in 20 mM sodium phosphate buffer at 40 °C and pH 7.0, 1.0 mg ml^?1 ginsenoside Rb2 was transformed into 0.47 mg ml^?1 ginsenoside 20(S)-Rg3 within 120 min, with a corresponding molar conversion yield of 65 %. Bgp2 hydrolyzed the ginsenoside Rb2 along the following pathway: Rb2 → Rd → 20(S)-Rg3. This is the first report of the biotransformation of ginsenoside Rb2 to ginsenoside 20(S)-Rg3 using the recombinant glycosidase.     

Natural antibodies to glycans

A wide variety of so-called natural antibodies (nAbs), i.e. immunoglobulins generated by B-1 cells, are directed to glycans. nAbs to glycans can be divided in three groups: 1) conservative nAbs, i.e. practically the same in all healthy donors with respect to their epitope specificity and level in blood; 2) allo-antibodies to blood group antigens; 3) plastic antibodies related to the first or the second group but discussed separately because their level changes considerably during diseases and some temporary conditions, in particular inflammation and pregnancy. Antibodies from the third group proved to be prospective markers of a number of diseases, whereas their unusual level (below or above the norm) is not necessarily the consequence of disease/state. Modern microarrays allowed the determination of the human repertoire, which proved to be unexpectedly broad. It was observed that the content of some nAbs reaches about 0.1% of total immunoglobulins. Immunoglobulins of M class dominate for most nAbs, constituting up to 80-90%. Their affinity (to a monovalent glycan, in K _D terms) was found to be within the range 10^?4–10^?6 M. Antibodies to Galβ1-3GlcNAc (Le^C), 4-HSO₃Galβ1-4GalNAc (4′-O-SuLN), Fucα1-3GlcNAc, Fucα1-4GlcNAc, GalNAcα1-3Gal (A_di), Galα1-4Galβ1-4Glc (P^k), Galα1-4Galβ1-4GlcNAc (P₁), GlcNAcα-terminated glycans, and hyaluronic acid should be noted among the nAbs revealed and studied during the last decade. At the same time, a kind of “taboo” is observed for a number of glycans: antibodies to LeX and Le^Y, and almost all gangliosides have not been observed in healthy persons. Many of the revealed nAbs were directed to constrained inner (core) part of glycan, directly adjoined to lipid of cell membrane or protein. The biological function of these nAbs remains unclear; for anti-core antibodies, a role of surveillance on appearance of aberrant, especially cancer, antigens is supposed. The first data related to oncodiagnostics based on quantitation of anti-glycan nAbs are reported.     

Biogeochemical regime shifts in coastal landscapes: the contrasting effects of saltwater incursion and agricultural pollution on greenhouse gas emissions from a freshwater wetland

Many coastal plain wetlands receive nutrient pollution from agricultural fields and are particularly vulnerable to saltwater incursion. Although wetlands are a major source of the greenhouse gases methane (CH₄) and nitrous oxide (N₂O), the consequences of salinization for greenhouse gas emissions from wetlands with high agricultural pollution loads is rarely considered. Here, we asked how saltwater exposure alters greenhouse gas emissions from a restored freshwater wetland that receives nutrient loading from upstream farms. During March to November 2012, we measured greenhouse gases along a ~2 km inundated portion of the wetland. Sampling locations spanned a wide chemical gradient from sites receiving seasonal fertilizer nitrogen and sulfate (SO₄ ^2?) loads to sites receiving seasonal increases in marine salts. Concentrations and fluxes of CH₄ were low (<100 µg L^?1 and <10 mg m^?2 h^?1) for all sites and sampling dates when SO₄ ^2? was high (>10 mg L^?1), regardless of whether the SO₄ ^2? source was agriculture or saltwater. Elevated CH₄ (as high as 1,500 µg L^?1 and 45 mg m^?2 h^?1) was only observed on dates when air temperatures were >27 °C and SO₄ ^2? was <10 mg L^?1. Despite elevated ammonium (NH₄ ⁺) for saltwater exposed sites, concentrations of N₂O remained low (<5 µg L^?1 and <10 µg m^?2 h^?1), except when fertilizer derived nitrate (NO₃ ^?) concentrations were high and N₂O increased as high as 156 µg L^?1. Our results suggest that although both saltwater and agriculture derived SO₄ ^2? may suppress CH₄, increases in N₂O associated with fertilizer derived NO₃ ^? may offset that reduction in wetlands exposed to both agricultural runoff and saltwater incursion.     

Spatial and temporal dynamics of diffusive methane emissions in the Okavango Delta,northern Botswana,Africa

Global warming is associated with the continued increase in the atmospheric concentrations of greenhouse gases; carbon dioxide, methane (CH₄) and nitrous oxide. Wetlands constitute the largest single natural source of atmospheric CH₄ in the world contributing between 100 and 231 Tg year^?1 to the total budget of 503–610 Tg year^?1, approximately 60 % of which is emitted from tropical wetlands. We conducted diffusive CH₄ emission measurements using static chambers in river channels, floodplains and lagoons in permanent and seasonal swamps in the Okavango Delta, Botswana. Diffusive CH₄ emission rates varied between 0.24 and 293 mg CH₄ m^?2 h^?1, with a mean (±SE) emission of 23.2 ± 2.2 mg CH₄ m^?2 h^?1 or 558 ± 53 mg CH₄ m^?2 day^?1. These emission rates lie within the range reported for other tropical wetlands. The emission rates were significantly higher (P < 0.007) in permanent than in seasonal swamps. River channels exhibited the highest average fluxes at 31.3 ± 5.4 mg CH₄ m^?2 h^?1 than in floodplains (20.4 ± 2.5 mg CH₄ m^?2 h^?1) and lagoons (16.9 ± 2.6 mg CH₄ m^?2 h^?1). Diffusive CH₄ emissions in the Delta were probably regulated by temperature since emissions were highest (20–300 mg CH₄ m^?2 h^?1) and lowest (0.2–3.0 mg m^?2 h^?1) during the warmer-rainy and cooler winter seasons, respectively. Surface water temperatures between December 2010 and January 2012 varied from 15.3 °C in winter to 33 °C in summer. Assuming mean inundation of 9,000 km², the Delta’s annual diffusive emission was estimated at 1.8 ± 0.2 Tg, accounting for 2.8 ± 0.3 % of the total CH₄ emission from global tropical wetlands.     

Dynamic aggregation of the mid-sized gadolinium complex {Ph4[Gd(DTTA)(H2O)2]− 3}

A compound binding three Gd³⁺ ions, {Ph₄[Gd(DTTA)(H₂O)₂]^? ₃} (where H₅DTTA is diethylenetriaminetetraacetic acid), has been synthesized around a hydrophobic center made up of four phenyl rings. In aqueous solution the molecules start to self-aggregate at concentrations well below 1 mM as shown by the increase of rotational correlation times and by the decrease of the translational self-diffusion constant. NMR spectra recorded in aqueous solution of the diamagnetic analogue {Ph₄[Y(DTTA)(H₂O)₂]^? ₃} show that the aggregation is dynamic and due to intermolecular π-stacking interactions between the hydrophobic aromatic centers. From estimations of effective radii, it can be concluded that the aggregates are composed of two to three monomers. The paramagnetic {Ph₄[Gd(DTTA)(H₂O)₂]^? ₃} exhibits concentration-dependent ¹H NMR relaxivities with high values of approximately 50 mM^?1 s^?1 (30 MHz, 25 °C) at gadolinium concentrations above 20 mM. A combined analysis of ¹H NMR dispersion profiles measured at different concentrations of the compound and ¹⁷O NMR data measured at various temperatures was performed using different theoretical approaches. The fitted parameters showed that the increase in relaxivity with increasing concentration of the compound is due to slower global rotational motion and an increase of the Lipari–Szabo order parameter S ².     

Measurement of rate constants for quenching singlet oxygen with a Cypridina luciferin analog (2-methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazo[1,2-a]pyrazin-3-one) and sodium azide

The rate constants for [¹O₂] [MCLA] and [¹O₂][NaN₃] were measured by quenching the near-infrared emission (¹Δ_g→³∑_g) in steady state with MCLA and NaN₃, respectively. ¹O₂ was constantly generated by energy transfer to O₂ from Ar laser-excited Rose Bengal. The Stern—Volmer plots yielded the second-order rate constants of 2.94 × 10⁹ M^?1 S^?1 and 3.83 × 10⁸ M^?1 S^?1 for quenching ¹O₂ with MCLA and NaN₃ in water at pH 5.4, respectively. The ¹O₂ + MCLA reaction emitted light with maximum at 465 nm at pD 4.5 identical to the O₂^? + MCLA reaction.