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1.
Microbial adhesion is an important factor that can influence biodegradation of poorly water soluble hydrocarbons such as phenanthrene.
This study examined how adhesion to an oil–water interface, as mediated by 1-dodecanol, enhanced phenanthrene biodegradation
by Pseudomonas fluorescens LP6a. Phenanthrene was dissolved in heptamethylnonane and added to the aerobic aqueous growth medium to form a two phase
mixture. 1-Dodecanol was non-toxic and furthermore could be biodegraded slowly by this strain. The alcohol promoted adhesion
of the bacterial cells to the oil–water interface without significantly changing the interfacial or surface tension. Introducing
1-dodecanol at concentrations from 217 to 4,100 mg l−1 increased phenanthrene biodegradation by about 30% after 120 h incubation. After 100 h incubation, cultures initially containing
120 or 160 mg l−1 1-dodecanol had mineralized >10% of the phenanthrene whereas those incubated without 1-dodecanol had mineralized only 4.5%.
The production and accumulation of putative phenanthrene metabolites in the aqueous phase of cultures likewise increased in
response to the addition of 1-dodecanol. The results suggest that enhanced adhesion of bacterial cells to the oil–water interface
was the main factor responsible for enhanced biodegradation of phenanthrene to presumed polar metabolites and to CO2. 相似文献
2.
Accumulating evidence suggests that Aβ1–42–membrane interactions may play an important role in the pathogenesis of Alzheimer’s disease. However, the mechanism of this
structural transition remains unknown. In this work, we have shown that submicellar concentrations of sodium dodecyl sulfate
(SDS) can provide a minimal platform for Aβ1–42 self-assembly. To further investigate the relation between Aβ1–42 structure and function, we analyzed peptide conformation and aggregation at various SDS concentrations using circular dichroism
(CD), Fourier transform infrared spectroscopy, and gel electrophoresis. These aggregates, as observed via atomic force microscopy,
appeared as globular particles in submicellar SDS with diameters of 35–60 nm. Upon sonication, these particles increased in
disc diameter to 100 nm. Pyrene I
3/I
1 ratios and 1-anilinonaphthalene-8-sulfonic acid binding studies indicated that the peptide interior is more hydrophobic than
the SDS micelle interior. We have also used Forster resonance energy transfer between N-terminal labeled pyrene and tyrosine
(10) of Aβ1–42 in various SDS concentrations for conformational analysis. The results demonstrate that SDS at submicellar concentrations
accelerates the formation of spherical aggregates, which act as niduses to form large spherical aggregates upon sonication.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
3.
Matthew J. Belousoff Gilles Gasser Bim Graham Yitzhak Tor Leone Spiccia 《Journal of biological inorganic chemistry》2009,14(2):287-300
A peptide nucleic acid (PNA) oligomer and a series of PNA conjugates featuring covalently attached pendant 1,4,7,10-tetraazacyclododecane
(cyclen) or bis((pyridin-2-yl)methyl)amine (DPA) moieties have been synthesized that are complementary to regions of the HIV-1
TAR messenger RNA stem-loop. Thermal denaturation studies, in conjunction win with native gel shift assays, suggest that the
PNAs “invade” TAR to produce a mixture of two 1:1 PNA–TAR adducts, tentatively assigned as an “open-duplex” structure, in
which the TAR stem-loop dissociates and the PNA hybridizes with its RNA complement via Watson–Crick base-pairing, and a triplex-type
structure, in which the initially displaced RNA segment is bound to the PNA:RNA duplex through Hoogsteen base-pairing. Thermal
denaturation experiments with the TAR sequence and single-stranded RNA and DNA oligonucleotides, both in the presence and
in the absence of Zn2+ ions, show that the introduction of cyclen or DPA ligand arms into the PNA oligomer leads to a small but reproducible increase
in the T
m values. This is attributed to hydrogen-bonding and/or electrostatic interactions between protonated forms of cyclen/DPA and
the cognate RNA or DNA oligonucleotide targets. Contrary to expectations, the addition of Zn2+ ions did not further enhance duplex formation through binding of Zn(II)–cyclen or Zn(II)–DPA moieties to the complementary
RNA or DNA. Native gel shift assays further confirmed the stability increase of the metal-free cyclen- and DPA-modified PNA
hybrids as compared with a control PNA sequence.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
Alberto Martínez Chandima S. K. Rajapakse Dalanda Jalloh Cula Dautriche Roberto A. Sánchez-Delgado 《Journal of biological inorganic chemistry》2009,14(6):863-871
We have measured water/n-octanol partition coefficients, pK
a values, heme binding constants, and heme aggregation inhibition activity of a series of ruthenium–π-arene–chloroquine (CQ) complexes recently reported to be active against CQ-resistant strains of Plasmodium falciparum. Measurements of heme aggregation inhibition activity of the metal complexes near water/n-octanol interfaces qualitatively predict their superior antiplasmodial action against resistant parasites, in relation to
CQ; we conclude that this modified method may be a better predictor of antimalarial potency than standard tests in aqueous
acidic buffer. Some interesting tendencies emerge from our data, indicating that the antiplasmodial activity is related to
a balance of effects associated with the lipophilicity, basicity, and structural details of the compounds studied.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
Markus Lenz Anne Marie Enright Vincent O’Flaherty Adriaan C. van Aelst Piet N. L. Lens 《Applied microbiology and biotechnology》2009,83(2):377-388
Whole-cell immobilization of selenate-respiring Sulfurospirillum barnesii in polyacrylamide gels was investigated to allow the treatment of selenate contaminated (790 μg Se × L−1) synthetic wastewater with a high molar excess of nitrate (1,500 times) and sulfate (200 times). Gel-immobilized S. barnesii cells were used to inoculate a mesophilic (30°C) bioreactor fed with lactate as electron donor at an organic loading rate
of 5 g chemical oxygen demand (COD) × L−1 day−1. Selenate was reduced efficiently (>97%) in the nitrate and sulfate fed bioreactor, and a minimal effluent concentration
of 39 μg Se × L−1 was obtained. Scanning electron microscopy with energy dispersive X-ray (SEM–EDX) analysis revealed spherical bioprecipitates
of ≤2 μm diameter mostly on the gel surface, consisting of selenium with a minor contribution of sulfur. To validate the bioaugmentation
success under microbial competition, gel cubes with immobilized S. barnesii cells were added to an Upflow Anaerobic Sludge Bed (UASB) reactor, resulting in earlier selenate (24 hydraulic retention
times (HRTs)) and sulfate (44 HRTs) removal and higher nitrate/nitrite removal efficiencies compared to a non-bioaugmented
control reactor. S. barnesii was efficiently immobilized inside the UASB bioreactors as the selenate-reducing activity was maintained during long-term
operation (58 days), and molecular analysis showed that S. barnesii was present in both the sludge bed and the effluent. This demonstrates that gel immobilization of specialized bacterial strains
can supersede wash-out and out-competition of newly introduced strains in continuous bioaugmented systems. Eventually, proliferation
of a selenium-respiring specialist occurred in the non-bioaugmented control reactor, resulting in simultaneous nitrate and
selenate removal during a later phase of operation.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
6.
Six different molecular dynamics simulations of Cyclophilin A, three with the protein free in water and three with the Ala-Pro
dipeptide bound to the protein, have been performed, and analysed with respect to structure and hydration of the active site.
The water structure in the binding pocket of the free Cyclophilin A was found to mimic the experimentally obtained binding
cis conformation of the dipeptide. Cyclophilin A is a peptidyl–prolyl cis–trans isomerase (PPIase), but the mechanism of the cis/trans isomerization is not exactly clear. This study was performed to understand better the binding between dipeptide and Cyclophilin
A, but also two previously proposed isomerization mechanisms are discussed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
7.
Joerns Fickel Heidi C. Hauffe Elena Pecchioli Ramon Soriguer Ljiljana Vapa Christian Pitra 《European Journal of Wildlife Research》2008,54(3):495-510
A substantial portion of today’s biodiversity is attributed to the climatic oscillations of the Pleistocene Ice Ages. Gradual
but dramatic climate changes were accompanied by expansion, contraction, and isolation of populations, promoting the accumulation
of genome differences and adaptations in refugial populations and resulting in allopatric differentiation in a variety of
taxa. In the present study, partial mitochondrial DNA sequences of the widely distributed European brown hare (Lepus europaeus) were analyzed to test whether the species’ present genetic structure is the result of postglacial re-colonization of Europe
from Asia Minor (clade A) and the Balkans (clade B) only, as suggested previously, or if additional refugia are likely. Analyses indicated the presence of an additional refugium
(Italy, clade I). The genealogic network of Italian hares displayed the tree-like structure expected from refugial populations, whereas central
European brown hare haplotypes revealed a clear star-phylogeny indicative of past-bottleneck population growth. This population
size expansion, which was confirmed by mismatch analysis, was estimated to have occurred ∼50–55 thousand years ago (kya).
The divergence of clade A* from the remaining matrilines is estimated at 239 kya, whereas the divergence of the ancestors of clades B* and I from A* occurred about 128 kya.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
8.
Mireia Güell Josep M. Luis Miquel Solà Per E. M. Siegbahn 《Journal of biological inorganic chemistry》2009,14(2):229-242
Tyrosinase catalyzes the ortho hydroxylation of monophenols and the subsequent oxidation of the diphenolic products to the resulting quinones. In efforts
to create biomimetic copper complexes that can oxidize C–H bonds, Stack and coworkers recently reported a synthetic μ-η2:η2-peroxodicopper(II)(DBED)2 complex (DBED is N,N′-di-tert-butylethylenediamine), which rapidly hydroxylates phenolates. A reactive intermediate consistent with a bis-μ-oxo-dicopper(III)-phenolate
complex, with the O–O bond fully cleaved, is observed experimentally. Overall, the evidence for sequential O–O bond cleavage
and C–O bond formation in this synthetic complex suggests an alternative mechanism to the concerted or late-stage O–O bond
scission generally accepted for the phenol hydroxylation reaction performed by tyrosinase. In this work, the reaction mechanism
of this peroxodicopper(II) complex was studied with hybrid density functional methods by replacing DBED in the μ-η2:η2-peroxodicopper(II)(DBED)2 complex by N,N′-dimethylethylenediamine ligands to reduce the computational costs. The reaction mechanism obtained is compared with the
existing proposals for the catalytic ortho hydroxylation of monophenol and the subsequent oxidation of the diphenolic product to the resulting quinone with the aim
of gaining some understanding about the copper-promoted oxidation processes mediated by 2:1 Cu(I)O2-derived species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
9.
Parallelisms and paraphyletic assemblages are common among ovenbirds. Molecular markers are therefore the best approach when
studying the evolutionary relationships among the members of this unparalleled diversified family. We obtained nucleotide
sequence data from mitochondrial (cytochrome b) and nuclear genes (myoglobin and glyceraldehyde-3-phosphodehydrogenase) and used these to deduce the phylogenetic position
of a monotypic genus endemic to the austral temperate rainforests of southern South America, the Des Murs’ Wiretail (Sylviorthorhynchus
desmursii Des Murs, 1847, Aves: Furnariidae). Phylogenetic analyses based on maximum parsimony, maximum likelihood and Bayesian inference
all converged into a congruent topology, with a basal position of Des Murs’ Wiretail within Synallaxinae together with Tit–Spinetails
(Leptasthenura). Our data reject the hypothesis of a phylogenetic relationship between Des Murs’ Wiretail and thistletails (Schizoeaca) which exhibit parallelisms in morphology, tail structure and nest architecture. Using a molecular clock based on the myoglobin
intron 2 gene, we estimated a divergence time of Des Murs’ Wiretail from Tit-Spinetails of 14–15 Myr, which is associated
with the appearance of sclerophyllous forest elements in Chile at the Middle–Upper Miocene.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
10.
Paavo Ahvenniemi Matthias Wolf Mari J. Lehtonen Paula Wilson Malgorzata German-Kinnari Jari P. T. Valkonen 《Journal of molecular evolution》2009,69(2):150-163
The rRNA cistron (18S–ITS1–5.8S–ITS2–28S) is used widely for phylogenetic analyses. Recent studies show that compensatory
base changes (CBC) in the secondary structure of ITS2 correlate with genetic incompatibility between organisms. Rhizoctonia solani consists of genetically incompatible strain groups (anastomosis groups, AG) distinguished by lack of anastomosis between
hyphae of strains. Phylogenetic analysis of internal transcribed spacer (ITS) sequences shows a strong correlation with AG
determination. In this study, ITS sequences were reannotated according to the flanking 5.8S and 28S regions which interact
during ribogenesis. One or two CBCs were detected between the ITS2 secondary structure of AG-3 potato strains as compared
to AG-3 tobacco strains, and between these two strains and all other AGs. When a binucleate Rhizoctonia species related to Ceratobasidiaceae was compared to the AGs of R. solani, which were multinucleate (3–21 nuclei per cell), 1–3 CBCs were detected. The CBCs in potato strains of AG-3 distinguish
them from AG-3 tobacco strains and other AGs yielding further evidence that the potato strains of AG-3 originally described
as R. solani are a species distinct from other AGs. The ITS1–5.8S–ITS2 sequences were analyzed by direct sequencing of PCR products from
497 strains of AG-3 isolated from potato. The same 10 and 4 positions in ITS1 and ITS2, respectively, contained variability
in 425 strains (86%). Nine different unambiguous ITS sequences (haplotypes) could be detected in a single strain by sequencing
cloned PCR products indicating that concerted evolution had not homogenized the rRNA cistrons in many AG-3 strains. Importantly,
the sequence variability did not affect the secondary structure of ITS2 and CBCs in AG-3.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
11.
Force–Velocity Curves of Motor Proteins Cooperating In Vivo 总被引:1,自引:0,他引:1
Shtridelman Y Cahyuti T Townsend B DeWitt D Macosko JC 《Cell biochemistry and biophysics》2008,52(1):19-29
Motor proteins convert chemical energy into work, thereby generating persistent motion of cellular and subcellular objects.
The velocities of motor proteins as a function of opposing loads have been previously determined in vitro for single motors.
These single molecule “force–velocity curves” have been useful for elucidating motor kinetics and for estimating motor performance
under physiological loads due to, for example, the cytoplasmic drag force on transported organelles. Here we report force–velocity
curves for single and multiple motors measured in vivo. Using motion enhanced differential interference contrast (MEDIC) movies
of living NT2 (neuron-committed teratocarcinoma) cells at 37°C, three parameters were measured—velocity (v), radius (a), and effective cytoplasmic viscosity (η′)—as they applied to moving vesicles. These parameters were combined in Stokes’
equation, F = 6πaη′v, to determine the force, F, required to transport a single intracellular particle at velocity, v. In addition, the number of active motors was inferred from the multimodal pattern seen in a normalized velocity histogram.
Using this inference, the resulting in vivo force–velocity curve for a single motor agrees with previously reported in vitro
single motor force–velocity curves. Interestingly, however, the curves for two and three motors lie significantly higher in
both measured velocity and computed force, which suggests that motors can work cooperatively to attain higher transport forces
and velocities.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
Extensive networks of deep drains are being built in Western Australia to reduce the effects of dryland salinity on agricultural
lands. Most of these drains discharge into natural river and wetland systems, with little consideration given to the environmental
impacts. This study examined the downstream ecological impacts of one of the oldest deep drain networks in Western Australia,
located in the Wakeman subcatchment near Narembeen. Twelve sites were sampled bi-monthly from October 2004 to September 2006.
On each occasion, water quality parameters were measured and the macro-invertebrate fauna was sampled. Significant differences
in water quality and macro-invertebrates were observed between the untreated sites and those affected by the drain discharge.
Surface water at untreated sites was always fresh (<3 ppt), alkaline (pH 7.6–8.9) and turbid (49–600 NTU), whereas treatment
sites were always saline (28–147 ppt), acidic (pH 1.9–3.8) and mostly clear (0–100 NTU). No recovery of water quality was
observed with distance from discharge point (20 km). Invertebrates reflected differences in water quality, with drain discharge
resulting in a sharp decline in species richness, and significant changes in macro-invertebrate community composition. Sites
affected by drain discharge were dominated by fly larvae such as Orthocladiinae and Ceratopogonidae. Microcrustaceans were
far more abundant at sites unaffected by drainage. The ecological values of Wheatbelt streams are likely to be further compromised
by discharge of poor water quality from deep drainage.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Handling editor: K. Martens 相似文献
13.
Natdanai Fafaungwithayakul Pranithi Hongsprabhas Parichat Hongsprabhas 《Food biophysics》2011,6(3):407-415
This study investigated physicochemical properties of soy soluble polysaccharide (SSP) and pectinase-hydrolysed soy soluble
polysaccharide (PH-SSP) from okara, the residue from soy milk production, and their influences when used as a fibre source
in oil-in-water (o/w) emulsions. Although pectinase hydrolysed only the carbohydrate fraction in SSP, it resulted in the self-association
of PH-SSP to the large-size aggregates. When PH-SSP was added to liquid emulsion containing 3.33% (w/v) rice bran oil and 3.75% (w/v) heated soy protein, it regulated the contents of protein in serum phase, sediment phase and at oil–water interface. The
types and contents of soy proteins in the serum phase and sediment phase could be manipulated by pre-heating of soy proteins
at 80 °C for 30 min and the addition of PH-SSP. The presence of PH-SSP (0–6% w/v) induced different distribution of proteins to the sediment phase and subsequent in vitro protein digestion in the emulsion.
Overall, this study proposed the means to design the distributions of proteins in different phases of o/w emulsion for different
degrees of oil release, emulsion stability and protein-polysaccharide coacervation during the course of in vitro peptic and
tryptic digestion. 相似文献
14.
Dinesh C. Soares Paul N. Barlow David J. Porteous Rebecca S. Devon 《Journal of molecular modeling》2009,15(2):113-122
Defects in the human ALS2 gene, which encodes the 1,657-amino-acid residue protein alsin, are linked to several related motor neuron diseases. We created
a structural model for the N-terminal 690-residue region of alsin through comparative modelling based on regulator of chromosome
condensation 1 (RCC1). We propose that this alsin region contains seven RCC1-like repeats in a seven-bladed beta-propeller
structure. The propeller is formed by a double clasp arrangement containing two segments (residues 1–218 and residues 525–690).
The 306-residue insert region, predicted to lie within blade 5 and to be largely disordered, is poorly conserved across species.
Surface patches of evolutionary conservation probably indicate locations of binding sites. Both disease-causing missense mutations—Cys157Tyr
and Gly540Glu—are buried in the propeller and likely to be structurally disruptive. This study aids design of experimental
studies by highlighting the importance of construct length, will enhance interpretation of protein–protein interactions, and
enable rational site-directed mutagenesis.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
We investigated seasonal variation of grazing impact of the pigmented nanoflagellates (PNF) with different sizes upon Synechococcus in the subtropical western Pacific coastal waters using grazing experiments with fluorescently labeled Synechococcus (FLS). For total PNF, conspicuous seasonal variations of ingestion rates on Synechococcus were found, and a functional response was observed. To further investigate the impact of different size groups, we separated
the PNF into four categories (<3, 3–5, 5–10, and >10 μm). Our results indicated that the smallest PNF (<3 μm PNF) did not
ingest FLS and was considered autotrophic. PNF of 3–5 μm in size made up most of the PNF community; however, their ingestion
on Synechococcus was too low (0.1–1.9 Syn PNF−1 h−1) to support their growth, and they had to depend on other prey or photosynthesis to survive. The ingestion rate of the 3–5 μm
group exhibited no significant seasonal variation; by contrast, the ingestion rates of 5–10 and >10 μm PNFs showed significant
seasonal variation. During the warm season, 3–5 μm PNF were responsible for the grazing of 12% of Synechococcus production, 5–10 μm PNF for 48%, and >10 μm PNF for 2%. Taken together, our results demonstrate that the PNF of 3–10 μm consumed
most Synechococcus during the warm season and exhibited a significant functional response to the increase in prey concentration. 相似文献
16.
Erick S. Van Dyke Dennis L. Scarnecchia Brian C. Jonasson Richard W. Carmichael 《Hydrobiologia》2009,625(1):27-42
Winter concealment habitat quality was assessed and its use by juvenile spring Chinook salmon (Oncorhynchus tshawytscha) quantified in three hatching areas of the Grande Ronde River Basin, Oregon USA. Fish densities were significantly higher
in pools with a higher winter concealment habitat index than pools with a lower index. The mean fork length and mean growth
rate of fish did not differ between pools with a higher or lower winter concealment habitat index, even though residual fish
were significantly larger than fish that emigrated. Biomass–density was significantly higher in pools with a higher winter
concealment habitat index than pools with a lower index in all three hatching areas. Biomass–density was positively associated
with the amount of cobble substrate (10–24.9 cm/m2) in all three hatching areas, and inversely associated with embeddedness in two of the hatching areas. Results of this study
indicate that enhancing winter concealment habitat could improve habitat quality resulting in increased carrying capacity
and winter usage by juvenile spring Chinook salmon.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Handling editor: J. A. Cambray 相似文献
17.
Yu MA Hou Y Gong GH Zhao Q Zhu XB Jiang L Yang XL Liao F 《Journal of industrial microbiology & biotechnology》2009,36(1):157-162
The effects of industrial storage on the changes of the cell viability and the activities of intracellular alcohol dehydrogenase
(ADH) and glucose-6-phosphate dehydrogenase (G6PDH) in brewer’s yeast, and the corresponding capacity for the bioconversion
of ethyl-3-oxobutanoate (EOB) to ethyl (S)-3-hydroxybutanoate ((S)-EHB), were investigated. The viability of fresh brewer’s yeast cells stored in industrial circulating cooling water at 1–2°C
showed 4 and 15% drop after the storage of 7 and 15 days, respectively, after which cells died rapidly. The pretreatment of
the stored brewer’s yeast cells by washing and screening significantly enhanced cell viability during industrial storage.
The intracellular levels of ADH and G6PDH after permeabilization of these stored cells with cetyltrimetylammonium bromide
(CTAB) were much higher, which showed only slight decrease within 2 weeks during the industrial storage. When the stored cells
after the permeabilization treatment was used as the biocatalyst at 90–120 g/L, EOB was converted almost completely into enantiopure
(S)-EHB with an enantiomeric excess (ee) more than 99% and a yield of over 96%, by fed-batch bioconversion of 560 mM EOB within 6 h.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
18.
The dynamics of aseasonal lowland dipterocarp forest in Borneo is influenced by perturbation from droughts. These events might
be increasing in frequency and intensity in the future. This paper describes drought-affected dynamics between 1986 and 2001
in Sabah, Malaysia, and considers how it is possible, reliably and accurately, to measure both coarse- and fine-scale responses
of the forest. Some fundamental concerns about methodology and data analysis emerge. In two plots forming 8 ha, mortality,
recruitment, and stem growth rates of trees ≥10 cm gbh (girth at breast height) were measured in a ‘pre-drought’ period (1986–1996), and in a period (1996–2001) including the 1997–1998
ENSO-drought. For 2.56 ha of subplots, mortality and growth rates of small trees (10–<50 cm gbh) were found also for two sub-periods (1996–1999, 1999–2001). A total of c. 19 K trees were recorded. Mortality rate increased by 25% while both recruitment and relative growth rates increased by
12% for all trees at the coarse scale. For small trees, at the fine scale, mortality increased by 6% and 9% from pre-drought
to drought and on to ‘post-drought’ sub-periods. Relative growth rates correspondingly decreased by 38% and increased by 98%.
Tree size and topography interacted in a complex manner with between-plot differences. The forest appears to have been sustained
by off-setting elevated tree mortality by highly resilient stem growth. This last is seen as the key integrating tree variable
which links the external driver (drought causing water stress) and population dynamics recorded as mortality and recruitment.
Suitably sound measurements of stem girth, leading to valid growth rates, are needed to understand and model tree dynamic
responses to perturbations. The proportion of sound data, however, is in part determined by the drought itself.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Bocian W Sitkowski J Bednarek E Tarnowska A Kawecki R Kozerski L 《Journal of biomolecular NMR》2008,40(1):55-64
Here we present evidence that in water/acetonitrile solvent detailed structural and dynamic information can be obtained for
important proteins that are naturally present as oligomers under native conditions. An NMR-derived human insulin monomer structure
in H2O/CD3CN, 65/35 vol%, pH 3.6 is presented and compared with the available X-ray structure of a monomer that forms part of a hexamer
(Acta Crystallogr. 2003 Sec. D59, 474) and with NMR structures in water and organic cosolvent. Detailed analysis using PFGSE
NMR, temperature-dependent NMR, dilution experiments and CSI proves that the structure is monomeric in the concentration and
temperature ranges 0.1–3 mM and 10–30°C, respectively. The presence of long-range interstrand NOEs, as found in the crystal
structure of the monomer, provides the evidence for conservation of the tertiary structure. Starting from structures calculated
by the program CYANA, two different molecular dynamics simulated annealing refinement protocols were applied, either using
the program AMBER in vacuum (AMBER_VC), or including a generalized Born solvent model (AMBER_GB).
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Wojciech Bocian contributed equally to this work. 相似文献
20.
Li-Chun Tseng Hans-Uwe Dahms Qing-Chao Chen Jiang-Shiou Hwang 《Helgoland Marine Research》2009,63(4):327-337
The South China Sea (SCS) is the world’s largest marginal sea being notable for vertical mixing at various scales resulting
in a sequence of chemical and biological dynamics in surface waters. We investigated the ingestion, gut content, evacuation
and clearance rates of copepods collected from six stations (including a South East Asia Time Series station) along a transect
line in the tropical of a SCS cruise during September 27, 1999 to October 2, 1999. The goal of the present study was to understand
the feeding ecology of copepods in the upper water layers (0–5 m) of the northern SCS during autumn. We measured the gut pigment
contents of 33 copepod species by the gut fluorescence method. The gut chlorophyll a values of most small size copepods (<1 mm) were lower than 1.00 ng Chl a individual−1. The highest gut pigment content was recorded in Scolecithrix danae (7.07 ng Chl a individual−1). The gut pigment contents of 33 copepod species (including 70 samples and 1,290 individuals) estimated is negatively correlated
with seawater temperature (Pearson correlation r = −0.292, P = 0.014) and is positively correlated with the chlorophyll a concentration of ambient waters (Pearson correlation r = 0.243, P = 0.043). Mean gut pigment content, ingestion and clearance rates (from 80 samples and 1,468 individuals) show that larger
copepods (>2 mm) had significantly higher values than medium sized copepods (1–2 mm) and smaller sized copepods. The present
study shows that the performance of feeding on phytoplankton was variable in different sized copepod groups, suggesting that
copepods obtained in the tropical area of the southeastern Taiwan Strait might be opportunistic feeders. 相似文献