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1.
George G. Harrigan Jerry Colca Sándor Szalma László G. Boros 《Metabolomics : Official journal of the Metabolomic Society》2006,2(1):21-29
The mitochondrial membrane protein termed “mitoNEET,” is a putative secondary target for insulin-sensitizing thiazolidinedione (TZD) compounds but its role in regulating metabolic flux is not known. PNU-91325 is a thiazolidinedione derivative which exhibits high binding affinity to mitoNEET and lowers cholesterol, fatty acid and blood glucose levels in animal models. In this study we report the stable isotope-based dynamic metabolic profiles (SIDMAP) of rosiglitazone, pioglitazone and PNU-91325 in a dose-matching, dose-escalating study. One and 10 μM concentrations 1 and 10 μM drug concentrations were introduced into HepG2 cells in the presence of either [1,2−13C2]-D-glucose or [U−13C18]stearate, GC/MS used to determine positional tracer incorporation (mass isotopomer analysis) into multiple metabolites produced by the Krebs and pentose cycles, de novo fatty acid synthesis, long chain fatty acid oxidation, chain shortening and elongation. Rosiglitazone and pioglitazone (10 μM) increased pentose synthesis from [U−13C18]stearate by 127% and 185%, respectively, while PNU-91325 rather increased glutamate synthesis in the Krebs cycle by 113% as compared to control vehicle treated cells. PNU-91325 also increased stearate chain shortening into palmitate by 59%. Glucose tracer-derived de novo palmitate and stearate synthesis were increased by 1 and 10 μM rosiglitazone by 41% and 83%, respectively, and by 63% and 75% by PNU-91325. Stearate uptake was also increased by 10 μM PNU-91325 by 15.8%. We conclude that the entry of acetyl Co-A derived from long-chain fatty acid β-oxidation into the mitochondria is facilitated by the mitoNEET ligand PNU-91325, which increases glucose-derived long chain fatty acid synthesis and breakdown via β-oxidation and anaplerosis in the mitochondria. 相似文献
2.
Seabuckthorn (Hippophae rhamnoides) is a multipurpose small tree with unique berries of high nutritional and pharmaceutical values. A clonally propagated plant
originating from a 20-year-old tree of H. r. rhamnoides × mongolica hybrid cultivar Julia and seedling offspring of this cultivar were investigated regarding induction of shoot organogenesis
in leaf explants and in roots of intact seedlings, and induction of direct somatic embryogenesis in explants from shoot tissue.
The highest percentage of leaf explants showing shoot organogenesis was achieved (juvenile explants, 65%; adult explants,
75%) when incubated in Murashige and Skoog (MS) medium supplemented with either 4.5 μM of the phenylurea cytokinin thidiazuron
(TDZ) or 2.25 μM TDZ plus 2.2 μM 6-benzyladenine (BA), for juvenile and adult explants, respectively, both supplemented with
0.53 μM α-naphthaleneacetic acid (NAA). Juvenile explants developed on average 18 shoots per explant in the MS medium supplemented
with 4.5 μM TDZ, a four fold increase over those incubated on the medium supplemented with 2.25 μM TDZ and 2.2 μM BA. Adult
leaf explants grown on medium containing 2.25 μM TDZ and 2.2 μM BA medium produced 12 shoots per explant, while those grown
on medium containing 4.5 μM TDZ produced 5 shoots per explant. Shoot organogenesis was observed in roots of intact seedlings
pre-cultured on plain medium lacking nutrients (PM) or woody plant medium (WPM) salts and then grown on WPM salts supplemented
with 4.4 μM BA, 0.29 μM gibberrelic acid (GA3), and 57.0 μM indoleacetic acid (IAA). The number of shoots formed on each seedling
root system was ten fold higher when the pre-culture was in WPM medium indicating a promoting effect of mineral nutrients
in the pre-culture medium. Somatic embryogenesis was induced in both juvenile and adult leaf explants in 65 and 78% of the
explants, respectively, in MS-based medium supplemented with 2.0 μM N-(2-Chloro-4-pyridyl)-N
1-phenylurea (CPPU), 0.53 μM NAA and varying concentrations of BA. There was an interaction effect between MS salt strength
and BA concentration. The most effective medium for inducing somatic embryogenesis in juvenile explants contained half strength
MS salts and 2.2 μM BA and full strength MS salts and 13.2 μM BA for adult explants. 相似文献
3.
The uptake of soluble phosphate by the green sulfur bacterium Chlorobium limicola UdG6040 was studied in batch culture and in continuous cultures operating at dilution rates of 0.042 or 0.064 h–1. At higher dilution rates, washout occurred at phosphate concentrations below 7.1 μM. This concentration was reduced to 5.1
μM when lower dilution rates were used. The saturation constant for growth on phosphate (K
μ) was between 2.8 and 3.7 μM. The specific rates of phosphate uptake in continuous culture were fitted to a hyperbolic saturation
model and yielded a maximum rate (Va
max) of 66 nmol P (mg protein)–1 h–1 and a saturation constant for transport (K
t) of 1.6 μM. In batch cultures specific rates of phosphate uptake up to 144 nmol P (mg protein)–1 h–1 were measured. This indicates a difference between the potential transport of cells and the utilization of soluble phosphate
for growth, which results in a significant change in the specific phosphorus content. The phosphorus accumulated within the
cells ranged from 0.4 to 1.1 μmol P (mg protein)–1 depending on the growth conditions and the availability of external phosphate. Transport rates of phosphate increased in
response to sudden increases in soluble phosphate, even in exponentially growing cultures. This is interpreted as an advantage
that enables Chl. limicola to thrive in changing environments.
Received: 9 February 1998 / Accepted: June 1998 相似文献
4.
Masłyk M Kochanowicz E Zieliński R Kubiński K Hellman U Szyszka R 《Molecular and cellular biochemistry》2008,312(1-2):61-69
Since Svf1 is phosphoprotein, we investigated whether it was a substrate for protein kinase CK2. According to the amino acid
sequence Svf1 harbours 20 putative CK2 phosphorylation sites. Here, we have reported cloning, overexpression, purification
and characterization of yeast Svf1 as a substrate for three forms of yeast CK2. Svf1 serves as a substrate for both the recombinant
CK2α (K
m 0.35 μM) and CK2α′ (K
m 0.18 μM) as well as CK2 holoenzyme (K
m 1.1 μM). Different K
m values argue that CK2β(β′) subunit has an inhibitory effect on the activity of both CK2α and CK2α′ towards surviving factor
Svf1. Reconstitution of α′2ββ′ isoform of CK2 holoenzyme shows that β/β′ subunits have regulatory effect depending on the kind of CK2 catalytic subunit.
This effect was not observed in the case of α2ββ′ isoform, which may be due to interaction between Svf1 and regulatory CK2β subunit (shown by co-immunoprecipitation experiments).
Interactions between CK2 subunits and Svf1 protein may have influence on ATP as well as ATP-competitive inhibitors (TBBt and
TBBz) binding. CK2 phosphorylates up to six serine residues in highly acidic peptide K199EVIPESDEEESSADEDDNEDEDEESGDSEEESGSEEESDSEEVEITYED248 of the Svf1 protein in vitro. Presented data may help to elucidate the role of protein kinase CK2 and Svf1 in the regulation
of cell survival pathways. 相似文献
5.
Several calcium-dependent protein kinases (CDPKs) are located in plant plasma membranes where they phosphorylate enzymes and transporters, like the H+-ATPase and water channels, thereby regulating their activities. In order to determine which kinases phosphorylate the H+-ATPase, a calcium-dependent kinase was purified from beetroot (Beta vulgaris L.) plasma membranes by anion-exchange chromatography, centrifugation in glycerol gradients and hydrophobic interaction chromatography. The kinetic parameters of this kinase were determined (V
max: 3.5 μmol mg−1 min−1, K
m
for ATP: 67 μM, K
m
for syntide 2: 15 μM). The kinase showed an optimum pH of 6.8 and a marked dependence on low-micromolar Ca2+ concentrations (K
d
: 0.77 μM). During the purification procedure, a 63-kDa protein with an isoelectric point of 4.7 was enriched. However, this protein was shown not to be a kinase by mass spectrometry. Kinase activity gels showed that a 50-kDa protein could be responsible for most of the activity in purified kinase preparations. This protein was confirmed to be a CDPK by mass spectrometry, possibly the red beet ortholog of rice CDPK2 and Arabidopsis thaliana CPK9, both found associated with membranes. This kinase was able to phosphorylate purified H+-ATPase in a Ca2+-dependent manner.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at . 相似文献
6.
Ki-Won Lee Kyung-Hee Kim Yong-Goo Kim Byung Hyun Lee Sang-Hoon Lee 《Acta Physiologiae Plantarum》2012,34(2):807-811
To identify potential candidates for acquiring stress tolerance, a new annealing control primer (ACP) system was used to identify
the differentially expressed genes. Alfalfa (Medicago sativa L.) seedlings were exposed to various abiotic stresses such as cold (4°C for 6 h), heat (42°C for 6 h), salt (300 mM for
6 h), drought (withdrawing irrigation for 48 h), copper (500 μM for 6 h), cadmium (500 μM for 6 h), and arsenic (500 μM for
6 h). Primer sets 41 and 93 were differentially expressed and identified as same sequence, which represents a mitochondrial
small heat-shock protein encoding gene, MsHsp23. This band was markedly increased or induced in alfalfa under heat, salt, and arsenic stresses. Differential expression of
MsHsp23 was further evaluated by Northern blot analysis. Temporal expression analysis showed that mRNA pool was altered as early
as 1 h of treatment. Thus, differential accumulation of MsHsp23 under heat, salt, and arsenic stresses suggests its potential involvement in diverse abiotic stress tolerance, and thereby
making a target for further molecular analysis. 相似文献
7.
Menachem J. Gunzburg Nigus D. Ambaye Jack T. Hertzog Mark P. Del Borgo Stephanie C. Pero David N. Krag Matthew C. J. Wilce Marie-Isabel Aguilar Patrick Perlmutter Jacqueline A. Wilce 《International journal of peptide research and therapeutics》2010,16(3):177-184
Surface plasmon resonance (SPR) is a useful biosensor technique for the study of biomolecular interactions, with the potential
for high-throughput screening of ligand interactions with drug targets. The key to its successful use, however, is in the
appropriate design of the experiment, including the mode of immobilization to the biosensor chip. We report an investigation
of the use of SPR for measuring the affinity of the G7-18NATE peptide ligand for its Grb7-SH2 domain target involved in the
migratory and proliferative potential of cancer cells. Previous studies have shown that the cyclic non-phosphorylated peptide,
G7-18NATE, inhibits Grb7 interactions with upstream binding partners and is able to inhibit both cell migration and proliferation
of cancer cells. We report the synthesis of a biotinylated G7-18NATE covalently attached to a linker (G7-18NATE-ASASASK-Biotin)
and compare its interaction with the Grb7-SH2 domain by SPR using three different immobilization strategies; immobilisation
of the peptide via streptavidin, immobilization of glutathione S-transferase (GST)-Grb7-SH2 domain via anti-GST antibody,
and immobilization of biotinylated Grb7-SH2 domain via streptavidin. This revealed that sensorgrams free from non-specific
binding and displaying simple kinetics were most readily achieved by immobilising the protein rather than the peptide, in
spite of the lower response associated with this method. K
D values of ~300 μM were determined for both strategies at pH 7.4. This compared with a K
D value of 4.4 μM at pH 6 demonstrating the importance of pH on this interaction. Overall, the immobilised protein systems
are most suitable for future comparative screening efforts using SPR. 相似文献
8.
A set of three relatively pristine seasonally inundated limesink wetlands and one riparian wetland was studied over a 4–6 month
long inundation period in 2001. Patterns in organic matter properties and oxygen consumption in the water column followed
a previously documented ecological gradient based on soil composition, vegetation type, and canopy cover. The full canopy,
cypress-gum swamp had the highest mean concentrations of dissolved organic carbon (DOC; 26.2 mg/l) and dissolved lignin (sum
6; 299 μg/l) with lower concentrations observed in the partial canopy, cypress savanna (22.0 mg/l DOC; 252 μg/l sum 6) and the open marsh savanna (20.6 mg/l DOC; 135 μg/l sum 6), respectively. During the inundation period, DOC increased in concentration, dissolved lignin decreased, and δ13C shifted to more positive values which collectively indicate a large reduction in the percentage of aromatic carbon during
the inundation period. All wetlands had very high concentrations of organic matter, yet microbial oxygen consumption was almost
always stimulated by the addition of glucose rather than inorganic nutrients. Stimulation by glucose suggests that there were
very small pools of highly bioavailable forms of DOC in the wetlands. A larger pool of moderately bioavailable organic matter
had the capacity to sustain microbial oxygen consumption rates under dark conditions for at least 15 d. During the inundation
period, the cypress-gum swamp had the lowest average rates of whole water oxygen consumption (1.0 μM/h) with increasing rates observed in the cypress savanna (1.3 μM/h), marsh savanna (1.6 μM/h), and riparian wetland (1.9 μM/h), respectively. The lignin compositional fingerprint varied across the gradient of limesink wetlands, and was useful for
identifying different sources of vascular plant-derived DOM. Vascular plant production, algal production, microbial respiration,
and UV degradation are all important drivers of DOM cycling, and the consistencies observed in this initial assessment of
seasonally inundated limesink wetlands suggest they vary in predictable ways across the ecological gradient. 相似文献
9.
Internode explants collected from in vitro grown shoots of two clones of Fagus sylvatica L. (European beech) and five clones of F. orientalis Lipski (Oriental beech) were used to evaluate their bud regeneration capacity. Adventitious shoot-buds formed on callus,
which developed from internode segments cultured in a Woody Plant Medium supplemented with different concentrations of either
thidiazuron (TDZ) or benzyladenine (BA). After 4 weeks of culture on induction media, the explants were transferred to a proliferation
medium supplemented with 2.2 μM BA, 9.1 μM zeatin and 2.9 μM indole-3-acetic acid (IAA) for another 8 weeks. Medium containing
TDZ was much more efficient than medium containing BA in inducing adventitious buds, the optimal TDZ concentration being 4.5
μM and the optimal BA concentration 17.8 μM. Genotypic variation in shoot regeneration capacity was observed among the two
Fagus species and between clones within each species, with a significant interaction between TDZ concentration and genotype regarding
mean bud number. Thidiazuron induction medium supplemented with a range of individual auxins was investigated, and it was
found that IAA or indole-3-butyric acid at 2.9 μM enhanced the bud forming capacity of explants. Morphogenic response varied
significantly with the position of the internode along the stem. The highest regeneration potential was obtained from apical
internodes, while those distal to the apex were the least productive. Elongated shoots of adventitious origin can be readily
proliferated by axillary branching.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
10.
Marco Scocchi Christine Lüthy Pietro Decarli Giuseppina Mignogna Philipp Christen Renato Gennaro 《International journal of peptide research and therapeutics》2009,15(2):147-155
Bac7, a cathelicidin peptide of the proline-rich group, inactivates bacteria in a stereospecific manner by entering target
cells without any apparent membrane damage and by binding to as yet unknown intracellular targets. The present study was aimed
at detecting these putative intracellular interactors, which might mediate the antibacterial action of this peptide. By using
affinity resins functionalized with the N-terminal 1-35 fragment of Bac7, a single protein was specifically retained with
high affinity from Escherichia coli cytoplasmic protein lysates. This ligand was identified as the heat shock protein DnaK, the Hsp70 homolog in E. coli. The interaction between the peptide and the chaperone is stereospecific, given that a resin prepared with the all-
d enantiomer failed to retain the protein. In vitro, Bac7(1-35) formed a complex with DnaK with an affinity comparable to that
of other known high-affinity peptide ligands. In addition, at 10–100 μM concentration, the peptide inhibited the protein refolding
activity of the complete DnaK/DnaJ/GrpE/ATP molecular chaperone system in a dose-dependent manner. Despite these results,
the in vitro sensitivity to the peptide, under growth permitting conditions, of DnaK-deficient E. coli strains was not significantly affected compared to the wild-type strain. This suggests that, apart from DnaK, other vital
targets for the proline-rich AMPs are present in susceptible bacteria.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Marco Scocchi and Christine Lüthy contributed equally to this work. 相似文献
11.
Acetylcholine (ACh, 1 μM) stimulates the activity of contractile vacuole of the amoeba Amoeba proteus. The ACh action is not reproduced by ACh analogs carbacholine and 5-methylfurmethide that are not hydrolized by acetylcholinesterase
(AChE). The ACh effect is not blocked by M-cholinolytics (atropine and metylone), but is suppressed by the N-cholynolytic
tubocurarine (0.01 μM). The AChE inhibitors eserine (0.001 μM) and armine (0.01 μM) suppress action of ACh on the amoeba contractile
vacuole. ACh does not affect the contractile vacuole activation produced by arginine-vasopressin (AVP, 1 μM), but blocks the
contractile vacuole activation caused by the ligand of opioid receptors dynorphin A (1–13) at a concentration of 0.1 μM. Based
on comparison of the obtained results with literature data, the conclusion is drawn that, in the described ACh effects, the
enzyme AChE plays the role of synergist, but not of antagonist. Regulation of the contractile vacuole activity and, hence,
the water-salt homeostasis of A. proteus is provided by three independent mechanisms through receptors of the AVP, ACh, and opioid systems. 相似文献
12.
Dissolved silicon (DSi) is a key marine nutrient. Sponges and diatoms are relevant DSi consumers, but sponges appear to have
a less efficient uptake system that requires higher ambient DSI concentrations for maximum uptake. We experimentally tested
whether a sponge adapted to live at the intertidal (Hymeniacidon perlevis) also shows such a need for high DSi. Under laboratory conditions, sponges were exposed to both the natural DSi concentration
(10 μM) and much higher levels (25, 40, and 70 μM) for 36 h, being water samples taken at 6 h intervals to infer DSi uptake.
Uptake rates shifted over time (particularly in high DSi treatments) and showed moderate inter-individual variability. Average
DSi uptake rate at 70 μM was twice higher than those at 40 and 25 μM, which in turn were not significantly different from
each other, but were twice higher than the uptake rate at 10 μM. Therefore, H. perlevis needs, for efficient uptake, ambient DSi concentrations two to four times higher than the maximum available in its natural
habitat. From an eco-physiological point of view, it means that the skeletal growth in the populations of H. perlevis is chronically limited by DSi availability, a limitation that may favor sponge evolution toward skeletal slimming. 相似文献
13.
Most plants are resistant to herbicides which inhibit acetyl-coenzyme A carboxylase (ACCase) because they have both eukaryotic
ACCase and herbicide-insensitive, prokaryotic ACCase. Members of the Gramineae are killed because they have only herbicide-sensitive,
eukaryotic ACCase. Here we report that a dicot, Erodium moschatum, is sensitive to the ACCase-inhibiting herbicide haloxyfop because it has herbicide-sensitive ACCase. Erodium moschatum was controlled by haloxyfop application at rates which controlled the gramineous species Digitaria ciliaris and a susceptible Lolium rigidum biotype but did not control the dicot Nicotiana tabacum or a haloxyfop-resistant L. rigidum biotype WLR96. Similarly, the haloxyfop acid concentration required to inhibit activity by 50% in E. moschatum ACCase assays (1.0 μM) was similar to that required for D. ciliaris (2.3 μM) and susceptible L. rigidum (0.4 μM) but much less than that for the resistant L. rigidum biotype WLR96 (353 μM) or the dicots N. tabacum (182 μM) and Pisum sativum (150 μM). Leaf protein extracts from N. tabacum and P. sativum contained both eukaryotic ACCase and prokaryotic subunits of ACCase, but E. moschatum, D. ciliaris and both L. rigidum biotypes exhibited only the eukaryotic ACCase. Thus, the dicot E. moschatum is sensitive to haloxyfop because it lacks the herbicide-insensitive prokaryotic ACCase, a protein that has been considered
ubiquitous in dicot species.
Received: 12 May 1998 / Accepted: 27 June 1998 相似文献
14.
Scott P. Burns Maria Gallo Barry L. Tillman 《In vitro cellular & developmental biology. Plant》2012,48(1):58-66
Agrobacterium-mediated transformation, employing direct shoot organogenesis, allows for mature transgenic plants to be obtained quickly
(3–4 mo). In this study, peanut (Arachis hypogaea L.) cultivars Florida-07, Georgia Green, Georgia Brown, New Mexico Valencia A, and VC-2 were selected to test their shoot
induction response for use in future transformation experiments. Two types of cotyledon explants were examined, those that
previously had an attached embryo axis upon cotyledon separation (explant A) and those that were embryo axis-free upon separation
(explant B). Explants were placed onto a shoot induction medium with N
6-benzyladenine concentrations ranging from 10–80 μM for Florida-07, Georgia Green, and VC-2; 10–20 μM for Georgia Brown; and
10–640 μM for New Mexico Valencia A. Following a 4-wk culture period, explants were visually rated based on a scale of 1–4,
where 1 indicated slight greening, but no growth, and 4 indicated greening, adventitious bud formation, as well as small leaf
expansion. A difference in shoot induction was observed for the cotyledon explants examined (P > t = <0.0001). Explant A had greater shoot induction with a visual rating of 1.8 ± 0.1; explant B had a rating of 1.6 ± 0.1
(P > t = <0.0001). Additionally, cultivars responded to the culture conditions differently (cultivar × N
6-benzyladenine interaction). Georgia Green on 10 μM N
6-benzyladenine produced the most shoot buds (24.6%) and the highest visual rating (2.1), followed by VC-2 on 10 μM N
6-benzyladenine (22.1%, 1.8), New Mexico Valencia A on 640 μM N
6-benzyladenine (21.4%, 1.8), Georgia Brown on 80 μM N
6-benzyladenine (9.0%, 1.7), and Florida-07 on 40 μM N
6-benzyladenine (7.1%, 1.8). Of the tested varieties, Georgia Green, New Mexico Valencia A, and VC-2 were best suited for future
transformation experiments based on their shoot bud production. 相似文献
15.
Surya Prakash Johannes Van Staden 《In vitro cellular & developmental biology. Plant》2008,44(4):338-341
A method for in vitro regeneration of Searsia dentata from nodal and shoot tip explants derived from mature trees is outlined. Nodal explants produced multiple shoots from the
axis when cultured on Murashige and Skoog (MS) medium containing 3% sucrose supplemented with 0, 5, 7.5, 10, or 12.5 μM N
6-benzyladenine (BA). An average of 5.3 shoots was obtained from nodal explants on 10 μM BA. For shoot tip explants, however,
supplementation of α-naphthaleneacetic acid (NAA) with BA favored a caulogenic response. A maximum of 6.1 shoots were produced
per shoot tip explant on MS containing 7.5 μM BA plus 5.0 μM NAA. The in vitro-regenerated shoots produced roots when transferred
to full-strength MS medium containing 3% sucrose and 10 μM indole-3-butyric acid (IBA). The developed plantlets were transferred
initially to a mist house. After an initial acclimatization period of 3–4 mo, plantlets were shifted to the greenhouse where
they thrived for 9 mo. The standardized protocol for mass propagation of S. dentata should eliminate the dependence on natural stands of plants for traditional medicinal purposes, and will also serve as a
means of conservation as the species is heavily overexploited. 相似文献
16.
Bernd Grünewald Anna Wersing 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2008,194(4):329-340
GABAergic inhibitory transmission is very abundant within the insect brain. We, therefore, studied the functional properties
of the ionotropic GABA receptor of honeybee mushroom body Kenyon cells in vitro. GABA applications elicit rapidly activating
and desensitizing currents, which are concentration-dependent between 10 and 500 μM. The mean peak amplitude induced by 500 μM
GABA at a holding potential of −110 mV is −1.55 ± 0.23 nA (SEM, n = 29). The GABA-induced current is mediated by Cl− ions because (1) the reversal potential of the GABA-induced current of −40.6 mV is very close to the calculated Nernst potential
of chloride (−44.8 mV). (2) With equimolar chloride concentrations the reversal potential shifted to about 0 mV. GABA or muscimol
are equally efficient channel agonists, whereas CACA is a partial agonist. Picrotoxin or philanthotoxin (100 μM) completely
and reversibly block the GABA-induced current, bicuculline (100 μM) has no effect. Elevating the intracellular Ca2+ concentration increases the GABA current amplitude. This modualtory effect is blocked by the kinase blocker K 252a, but not
by blockers of CaMkinaseII (KN-93), PKC (bisindolylmaleimide) or PKA (KT 5720). We conclude that Kenyon cells express functional
GABA receptors whose properties support an inhibitory role of GABAergic transmission. 相似文献
17.
A tetrameric lectin, with hemagglutinating activity toward rabbit erythrocytes and with specificity toward d-mannosamine and d(+)-mannose, was isolated from the ovaries of a teleost, the cobia Rachycentron canadum. The isolation protocol comprised ion exchange chromatography on CM-cellulose and Q-Sepharose, ion exchange chromatography
by fast protein liquid chromatography (FPLC) on Mono Q, and finally gel filtration by FPLC on Superose 12. The lectin was
adsorbed on all ion exchangers used. It exhibited a molecular mass of 180 kDa in gel filtration on Superose 12 and a single
45-kDa band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that it is a tetrameric protein. The
hemagglutinating activity of the lectin was stable up to 40°C and between pH 4 and pH 10. All hemagglutinating activity disappeared
at 60°C and at pH 1 and pH 13. The hemagglutinating activity was doubled in the presence of 0.1 μM FeCl3. The lectin exerted antibacterial activity against Escherichia coli with 50% inhibition at 250 μg. There was no antifungal activity toward Coprinus comatus, Fusarium oxysporum, Mycosphaerella arachidicola, and Rhizoctonia solani at a dose of 300 μg. The lectin exhibited maximal mitogenic response from mouse splenocytes at a concentration of 14 μM. 相似文献
18.
Two inhibitors, aviglycine and propargylglycine, were tested for their ability to suppress methionine synthesis thus inhibit
conidial germination and mycelial growth of Czapek-Dox liquid medium grown Fusarium oxysporum f. sp. luffae
μM. The linear inhibition range for mycelial growth was about 7.6–762.9 μM. Although aviglycine did not completely inhibit both conidial germination and mycelial growth, it showed significant inhibitory
effect at 1.5 μM. The inhibition range for propargylglycine against conidial germination and mycelial growth were from 0.08 to 8841 μM and from 0.8 to 884.1 μM, respectively. Propargylglycine inhibited conidial germination and mycelial growth at a concentration of 8841 μM. The EC50 values of aviglycine were 1 μM for conidial growth and 122 μM for mycelial growth, and the EC50 values of propargylglycine were 47.7 μM for conidial growth and 55.6 μM for mycelial growth. Supplement of methionine released inhibition of aviglycine or propargylglycine to conidial germination.
In addition, a mixture of aviglycine (1.5 μM) and propargylglycine (8841 μM) showed additive inhibitive effect than applied alone on 10 isolates. From these results, both aviglycine and propargylglycine
exhibited inhibitory activity, and suggest that they can provide potential tools to design novel fungicide against fungal
pathogens. 相似文献
19.
Alicja Piotrowska Andrzej Bajguz Romuald Czerpak Katarzyna Kot 《Journal of Plant Growth Regulation》2010,29(1):53-62
The present study was undertaken to test the influence of exogenously applied jasmonic acid (JA) at concentrations of 0.01–100 μM
upon the growth and metabolism of the aquatic plant Wolffia
arrhiza (Lemnaceae). JA acted in a concentration-dependent manner. JA at 0.1 μM stimulated plant growth and accumulation of cellular
components (proteins, monosaccharides, chlorophylls, phaeophytins, and carotenoids). Treatment with JA at 0.1 μM enhanced
W.
arrhiza viability by the induction of biomass production and increased the level of photosynthetic pigments, monosaccharides, and
soluble proteins. Moreover, JA at 0.1 μM activated the enzymatic (catalase, ascorbate peroxidase, NADH peroxidase) and nonenzymatic
antioxidant (ascorbate, glutathione) system in W.
arrhiza and, therefore, suppressed lipid peroxidation. In contrast, decreases in fresh weight, major photosynthetic pigments, monosaccharides,
and soluble protein content were observed in W. arrhiza exposed to 100 μM JA. JA applied at 100 μM also stimulated the formation of lipid peroxides which are responsible for membrane
damage. In the presence of 100 μM JA, antioxidant enzyme (catalase, ascorbate peroxidase, NADH peroxidase) activity and ascorbate
as well as glutathione content were inhibited. The data support the hypothesis that JA plays an important role in W.
arrhiza growth and metabolism, regulating oxidative status by direct influence on the enzymatic as well as nonenzymatic antioxidant
machinery. 相似文献
20.
Daniel Verbaro Andrew Hagarman Ajay Kohli Reinhard Schweitzer-Stenner 《Journal of biological inorganic chemistry》2009,14(8):1289-1300
We measured the circular dichroism (CD) and absorption spectra of the B-band region of microperoxidase 11 (MP11) as a function
of temperature and peptide concentration. At micromolar concentrations, small MP11 dimers or trimers lead to excitonic coupling
between low-spin and high-spin heme groups, to which the NH2 group of the MP11 N-terminal and H2O are bound as a sixth ligand, respectively. These aggregates convert into monomers with hexacoordinated high-spin heme groups
with increasing temperature. This transition can be described by a two-state model. Aggregation becomes more extended at 50 μM
concentration and causes some B-band hyperchromism, which reflects a J-type arrangement of heme groups linked together in
the aggregates formed. At near-millimolar concentration, the CD and absorption spectra of the B-band region suggest the existence
of even more extended and thermally stable aggregates, which might involve μ-oxo dimers of the heme groups. The degree of
aggregation at 50 and 500 μM concentration increases substantially if the sample is freed from most of its oxygen in a N2 atmosphere. The CD spectrum of the monomeric high-spin species is reminiscent of that observed for the unfolded alkaline
conformation of the intact protein. Finally, we investigated the binding of acetylmethionine (AcM) ligands to the heme at
aggregation-supporting conditions (500 μM concentration). The data suggest that the ligand prevents any substantial aggregation.
As a surprising result, our data reveal that AcM–MP11 complexes exhibit a high-spin/low-spin mixture, with the high-spin configuration
being stabilized at high temperatures. 相似文献