共查询到20条相似文献,搜索用时 31 毫秒
1.
Henry J. Nothnagel Matthew R. Preimesberger Matthew P. Pond Benjamin Y. Winer Emily M. Adney Juliette T. J. Lecomte 《Journal of biological inorganic chemistry》2011,16(4):539-552
In the absence of an exogenous ligand, the hemoglobins from the cyanobacteria Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7002 coordinate the heme group with two axial histidines (His46 and His70). These globins also form a covalent linkage
between the heme 2-vinyl substituent and His117. The in vitro mechanism of heme attachment to His117 was examined with a combination
of site-directed mutagenesis, NMR spectroscopy, and optical spectroscopy. The results supported an electrophilic addition
with vinyl protonation being the rate-determining step. Replacement of His117 with a cysteine demonstrated that the reaction
could occur with an alternative nucleophile. His46 (distal histidine) was implicated in the specificity of the reaction for
the 2-vinyl group as well as protection of the protein from oxidative damage caused by exposure to exogenous H2O2. 相似文献
2.
Balasubramanian Radhakrishnan Radha Prasanna Pranita Jaiswal Saswati Nayak Prem Dureja 《Biologia》2009,64(5):881-889
An investigation was undertaken to evaluate a set of cyanobacterial strains in terms of production of biocidal compounds exhibiting
allelochemical and fungicidal properties. Two cyanobacterial strains — Anabaena sp. and Calothrix sp. were selected for further investigation, on the basis of their larger inhibition zones on the lawn of Synechocystis and Synechococcus sp. and two phytopathogenic fungi — Rhizoctonia bataticola and Pythium debaryanum. The diameter of the inhibition zone was largest when extracellular filtrates of the two cultures incubated at high light
intensity (90–100 μmol photons m−2 s−1) and temperature (40 ± 2 °C) or grown in medium containing two-folds higher P (1.4 mg/L, as compared to 0.7 mg/L in BG 11
medium) were taken. A pH of 8 was the most optimal for both strains, in terms of growth and biocidal activity. Partial purification
of ethyl acetate extract using TLC, followed by GLC revealed a single peak. This study highlights the importance of environmental
factors in aggravating or reducing the toxic effects of these harmful cyanobacteria and their potential as a biocontrol agent. 相似文献
3.
We report a procedure for obtaining fairly pure phycocyanin from a local isolate of the cyanobacterium Synechococcus sp (Anacystis nidulans BD1). Cells were incubated with 1 mg∙mL−1 of lysozyme at 37°C for 16 h with shaking. The cell-free extract was treated with activated charcoal and chitosan. The purity
(A
620/280) of phycocyanin obtained after lysozyme treatment was up to 2.18, which could be improved to 4.72 after incubation with activated
charcoal and chitosan. The yield of phycocyanin was 80–100 mg∙g−1 dry weight of cells. The method reported here is a single-step and efficient procedure and has the potential to be adopted
for large-scale production of phycocyanin. 相似文献
4.
In this work, an over-expressed cyclobutane pyrimidine dimer (CPD) photolyase of Synechococcus sp. PCC 7942 was used to investigate UV-C (ultraviolet irradiation of C-region) influence on photoreactivation. In vivo photoreactivation experiments indicated that the survival rate decreased from 100 to 2.6% when the UV-C flux was increased
from 1.1 to 68.5 μW/cm2. It seemed that the photolyase was easily inactivated at UV-C intensities ≥25.5 μW/cm2. Spectrometric analysis indicated that tertiary structure of the photolyase changed evidently when the UV-C fluxes were ≥25.5
μW/cm2, while the secondary structure was almost unchanged even at 170 μW/cm2. Band shift assay indicated that catalytic activity of the photolyase was impaired at fluxes ≥25.5 μW/cm2, but no significant influence on DNA-binding activity was observed. These results suggest that photoreactivation is efficient
at UV-C fluxes ≤25.5 μW/cm2, but would be impaired by intense UV-C irradiation due to structure changes of the photolyase.
Published in Russian in Biokhimiya, 2007, Vol. 72, No. 5, pp. 668–673. 相似文献
5.
Orlita A Sidwa-Gorycka M Malinski E Czerwicka M Kumirska J Golebiowski M Lojkowska E Stepnowski P 《Biotechnology letters》2008,30(3):541-545
Growth of Ruta graveolens shoots was induced when Bacillus sp. cell lysates were added to the culture medium. Elicitation of coumarin by this lysate was also very effective; the concentrations
of isopimpinelin, xanthotoxin and bergapten increased to 610, 2120 and 1460 μg g−1 dry wt, respectively. It also had a significant effect on the production of psoralen and rutamarin (680 and 380 μg g−1 dry wt) and induced the biosynthesis of chalepin, which was not detected in the control sample, up to 47 μg g−1 dry wt With lysates of the Pectobacterium
atrosepticum, their effect on growth was not so significant and had no effect on the induction of coumarin accumulation. But elicitation
with this lysate was much more effective for inducing the production of furoquinolone alkaloids; the concentrations of γ-fagarine,
skimmianine, dictamnine and kokusaginine rose to 99, 680, 172 and 480 μg g−1 dry wt, respectively. 相似文献
6.
Alicja Szatanik-Kloc Patrycja Warchulska Grzegorz Józefaciuk 《Acta Physiologiae Plantarum》2009,31(1):59-64
The plants of winter rye variety Rostockie grown in nutrient solution prepared according to Marschner and Romheld (1983) were stressed at shooting stage with different zinc (ZnCl2) concentrations of 0, 20, 200 and 400 mgXdm−3 during 10 days at pH = 4.5. The control plants were grown continuously at pH = 7, without Zn2+. The roots of all plants were titrated with 0.1 molXdm−3 NaOH in 1 molXdm−3 NaCl solution with a rate 0.01 ml/min using auto-titrator Titrino 702 (Metrohm). The amount of the base consumed between
pH 3 and 10 was recorded with a step of 0.1 pH unit. From the titration data root surface charge was characterized. Roots
grown at pH = 4.5 without Zn2+ addition, had apparently the same charge properties as the control roots. Under 200 and 400 mgXdm−3 of zinc addition, variable charge, Q, and the cation exchange capacity, CEC, of the roots significantly decreased as did the fractions of surface acidic functional
groups of strong and medium acidity i.e. the groups having apparent surface dissociation constants, Kapp, between 10−3.5 and 10−5.5. For 20 mgXdm−3 zinc stress the fraction of weaker surface groups (surface dissociation constants around 10−6.5) decreased also. The surface charge density, SCD, of roots decreased under the Zn stress. 相似文献
7.
Belinda B. Wenke Juliette T. J. Lecomte Annie Héroux Jamie L. Schlessman 《Proteins》2014,82(3):528-534
The X‐ray structures of the hemoglobin from Synechococcus sp. PCC 7002 (GlbN) were solved in the ferric bis‐histidine (1.44 Å resolution) and cyanide‐bound (2.25 Å resolution) states with covalently attached heme. The two structures illustrate the conformational changes and cavity opening caused by exogenous ligand binding. They also reveal an unusually distorted heme, ruffled as in c cytochromes. Comparison to the solution structure demonstrates the influence of crystal packing on several structural elements, whereas comparison to GlbN from Synechocystis sp. PCC 6803 shows subtle differences in heme geometries and environment. The new structures will be instrumental in elucidating GlbN reactivity. Proteins 2014; 82:528–534. © 2013 Wiley Periodicals, Inc. 相似文献
8.
Background
Molecular hydrogen is an environmentally-clean fuel and the reversible (bi-directional) hydrogenase of the cyanobacterium Synechocystis sp. PCC 6803 as well as the native Escherichia coli hydrogenase 3 hold great promise for hydrogen generation. These enzymes perform the simple reaction 2H+ + 2e- ↔ H2 (g). 相似文献9.
Yaser Hassan Dewir Nisha Singh Shakira Shaik Ashley Nicholas 《In vitro cellular & developmental biology. Plant》2010,46(1):41-46
The present study reports a simple protocol for indirect shoot organogenesis and plant regeneration of Sutherlandia using rachis and stem segments. Different concentrations (0.0–68.08 μmol l−1) of thidiazuron (TDZ) were used for callus induction and shoot organogenesis. The highest percentage of callus formation
(97.5%) and the highest percentage of explants forming shoots (88.8%) were obtained from rachis explants cultured onto Murashige
and Skoog (MS) medium (Murashige and Skoog, Physiol. Plant. 15:473–495, 1962) supplemented with 45.41 μmol l−1 TDZ. Scanning electron microscopy demonstrated the early development of adventitious shoots derived from callus cultures.
Shoot clusters were further developed and grown in MS hormone-free medium. The presence of l-canavanine was determined by thin-layer chromatography and confirmed after column fractionation using silica gel and nuclear
magnetic resonance spectroscopy. Individual shoots were rooted on different concentrations and combinations of MS salt strength
and IBA. Half-strength MS salt medium supplemented with 24.6 μmol l−1 IBA was optimal for root induction in which 78% of shoots were rooted. The in vitro plants were successfully acclimatized in a growth chamber with a 90% survival rate. 相似文献
10.
This study was designed to identify rhizobial strains specific to greengram expressing higher tolerance against insecticides,
fipronil and pyriproxyfen, and synthesizing plant growth regulators even amid insecticide-stress. Of the 50 bradyrhizobial
isolates, the Bradyrhizobium sp. strain MRM6 showed tolerance up to 1,600 μg mL−1 against each of fipronil and pyriproxyfen. The tolerant Bradyrhizobium sp. (vigna) produced plant growth promoting substances in substantial amounts, both in the presence and absence of insecticides. The
strain MRM6 was further used to investigate its impact on greengram grown in soils treated with 200 (the recommended dose),
400 and 600 μg kg−1 soil of fipronil and 1,300 (the recommended dose), 2,600 and 3,900 μg kg−1 soil of pyriproxyfen. Fipronil at 600 μg kg−1 soils and pyriproxyfen at 3,900 μg kg−1 soils had greatest toxic effects and decreased plant biomass, symbiotic efficiency, nutrient uptake and seed yield of greengram
plants. The Bradyrhizobium sp. (vigna) inoculant when used with fipronil and pyriproxyfen significantly increased the measured parameters compared to the plants
grown in soils treated solely with the same concentration of each insecticide. This study inferred that the Bradyrhizobium sp. (vigna) strain MRM6 may be exploited as bio-inoculant to increase the productivity of greengram exposed to insecticide-stressed
soils. 相似文献
11.
B. Kozomara B. Vinterhalter Lj. Radojević D. Vinterhalter 《In vitro cellular & developmental biology. Plant》2008,44(2):142-147
A procedure for the micropropagation of Chimonanthus praecox (L) Link, wintersweet, has been developed using buds from adult trees excised in spring. Shoot cultures established on Murashige
and Skoog (1962) medium supplemented with 0.5 mg l−1 6-benzyladenine (BAP) and 0.1 mg l−1 indole-3-butyric acid (IBA) were difficult to maintain in vitro through extended periods of time due to browning of the medium, shoot and leaf necrosis, and hyperhydricity. A treatment
combining the use of 0.1% w/v activated charcoal and addition of a double phase agar-solidified/liquid medium improved propagation, enabling a successful
in vitro propagation scheme to be developed. Optimal shoot multiplication occurred on medium containing 0.5 mg l−1 BAP, and rooting on medium with 2.0 mg l−1 IBA for 7 d, followed by transfer to hormone-free medium. Rooted plantlets were easily acclimated in a glasshouse and replanted
and cultured outdoors. 相似文献
12.
We studied the nutritional modes of the orchid Serapias strictiflora and its mycorrhizal fungus Epulorhiza sp. using the differences in carbon isotopic composition (δ13C) of C3 orchid and C4 maize tissues. We found that if cultivated in substrate lacking any organic compounds, the mycorrhizal extraradical mycelia
(δ13C = −26.3 ± 0.2 ‰) developed well, despite being fully dependent on nutrition from orchid roots (δ13C = −28.6 ± 0.1 ‰). If the mycorrhizal fungus had additional access to and colonized decaying maize roots (δ13C = −14.6 ± 0.1 ‰), its isotopic composition (δ13C = −21.6 ± 0.4 ‰) reflected a mixture of biotrophy and saprotrophy. No statistically significant differences in δ13C of new storage tubers were found between Epulorhiza-associated orchids with (δ13C = -28.2 ± 0.1 ‰) and without access to maize roots (δ13C = −28.6 ± 0.2 ‰). We conclude that autotrophy is the predominant nutritional mode of mature S. strictiflora plants and that they supply their mycorrhizal fungus with substantial amount of carbon (69 ± 3 % of the fungus demand), even
if the fungus feeds saprotrophically. 相似文献
13.
Kinetics of styrene biodegradation by <Emphasis Type="Italic">Pseudomonas</Emphasis> sp. E-93486 总被引:1,自引:0,他引:1
The research into kinetics of styrene biodegradation by bacterial strain Pseudomonas sp. E-93486 coming from VTT Culture Collection (Finland) was presented in this work. Microbial growth tests in the presence
of styrene as the sole carbon and energy source were performed both in batch and continuous cultures. Batch experiments were
conducted for initial concentration of styrene in the liquid phase changed in the range of 5–90 g m−3. The Haldane model was found to be the best to fit the kinetic data, and the estimated constants of the equation were: μ
m = 0.1188 h−1, K
S = 5.984 mg l−1, and K
i = 156.6 mg l−1. The yield coefficient mean value
Y\textxs\textapp Y_{\text{xs}}^{\text{app}} for the batch culture was 0.72 gdry cells weight (gsubstrate)−1. The experiments conducted in a chemostat at various dilution rates (D = 0.035–0.1 h−1) made it possible to determine the value of the coefficient for maintenance metabolism m
d = 0.0165 h−1 and the maximum yield coefficient value
Y\textxs\textM = 0.913 Y_{\text{xs}}^{\text{M}} = 0.913 . Chemostat experiments confirmed the high value of yield coefficient
Y\textxs\textapp Y_{\text{xs}}^{\text{app}} observed in the batch culture. The conducted experiments showed high activity of the examined strain in the styrene biodegradation
process and a relatively low sensitivity to inhibition of its growth at higher concentrations of styrene in the solution.
Such exceptional features of Pseudomonas sp. E-93486 make this bacterial strain the perfect candidate for technical applications. 相似文献
14.
The PsbH protein of cyanobacterium Synechocystis sp. PCC 6803 was expressed as a fusion protein with glutathione-S transferase (GST) in E. coli grown on a mineral medium enriched in 15N isotope. After enzymatic cleavage of the fusion protein, the 1H-15N-HSQC spectrum of PsbH protein in presence of the detergent β-D-octyl-glucopyranoside (OG) was recorded on a Bruker DRX 500 MHz NMR spectrometer equipped with a 5 mm TXI cryoprobe to enhance the sensitivity and resolution. Non-labelled protein
was used for secondary structure estimation by deconvolution from circular dichroism (CD) spectra. Experimental results were
compared with our results from a structural model of PsbH using a restraint-based comparative modelling approach combined
with molecular dynamics and energetic modelling. We found that PsbH shows 34–38% α-helical structure (Thr36-Ser60), a maximum
of around 15% of β-sheet, and 12–19% of β-turn. 相似文献
15.
A genetic transformation system has been developed for callus cells of Crataegus
aronia using Agrobacterium
tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with
5 mg l−1 Indole-3-butyric acid (IBA) and 0.5 mg l−1 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different
types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red
colored callus was obtained on MS medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l−1 kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli
were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l−1 hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this
is the first time to report an Agrobacterium-mediated transformation system in Crataegus
aronia. 相似文献
16.
Biosorption is an eco-friendly and cost-effective method for treating the dye house effluents. Aspergillus niger and Trichoderma sp. were cultivated in bulk and biomasses used as biosorbents for the biosorption of an azo dye Orange G. Batch biosorption
studies were performed for the removal of Orange G from aqueous solutions by varying the parameters like initial aqueous phase
pH, biomass dosage, and initial dye concentration. It was found that the maximum biosorption was occurred at pH 2. Experimental
data were analyzed by model equations such as Langmuir and Freundlich isotherms, and it was found that both the isotherm models
best fitted the adsorption data. The monolayer saturation capacity was 0.48 mg/g for Aspergillus niger and 0.45 mg/g for Trichoderma sp. biomasses. The biosorption kinetic data were tested with pseudo first-order and pseudo second-order rate equations, and
it was found that the pseudo second-order model fitted the data well for both the biomasses. The rate constant for the pseudo
second-order model was found to be 10–0.8 (g/mg min−1) for Aspergillus niger and 8–0.4 (g/mg min−1) for Trichoderma sp. by varying the initial dye concentrations from 5 to 25 mg/l. It was found that the biomass obtained from Aspergillus niger was a better biosorbent for the biosorption of Orange G dye when compared to Trichoderma sp. 相似文献
17.
Sirisansaneeyakul S Singhasuwan S Choorit W Phoopat N Garcia JL Chisti Y 《Marine biotechnology (New York, N.Y.)》2011,13(5):928-941
The microalgae Chlorella protothecoides UTEX 25, Chlorella sp. TISTR 8991, and Chlorella sp. TISTR 8990 were compared for use in the production of biomass and lipids under photoautotrophic conditions. Chlorella sp. TISTR 8990 was shown to be potentially suitable for lipid production at 30°C in a culture medium that contained only
inorganic salts. For Chlorella sp. TISTR 8990 in optimal conditions in a stirred tank photobioreactor, the lipid productivity was 2.3 mg L−1 h−1 and after 14 days the biomass contained more than 30% lipids by dry weight. To attain this, the nitrogen was provided as
KNO3 at an initial concentration of 2.05 g L−1 and chelated ferric iron was added at a concentration of 1.2 × 10−5 mol L−1 on the ninth day. Under the same conditions in culture tubes (36 mm outer diameter), the biomass productivity was 2.8-fold
greater than in the photobioreactor (0.125 m in diameter), but the lipid productivity was only 1.2-fold higher. Thus, the
average low-light level in the photobioreactor actually increased the biomass specific lipid production compared to the culture
tubes. A light-limited growth model closely agreed with the experimental profiles of biomass production, nitrogen consumption,
and lipid production in the photobioreactor. 相似文献
18.
Meiru Li Hongqing Li Xiaoying Hu Xiaoping Pan Guojiang Wu 《Plant Cell, Tissue and Organ Culture》2010,102(3):321-327
Zoysia tenuifolia Willd. ex Trin. is one of the most popularly cultivated turfgrass. This is the first report of successful plant regeneration
and genetic transformation protocols for Z. tenuifolia using Agrobacterium tumefaciens. Initial calli was induced from stem nodes incubated on a Murashige and Skoog (1962) (MS) medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1 mg l−1 6-benzyladenine (BA), with a frequency of 53%. Compact calli were selected and subcultured monthly on the fresh medium. Sixty-nine
percent of the calli could be induced to regenerate plantlets when the calli incubated on a MS medium supplemented with 0.2 mg l−1 BA under darkness. For genetic transformation, calli were incubated with A. tumefaciens strain EHA105 harboring the binary vector pCAMBIA 1301 which contains the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene (gus-int) as a reporter gene. Following co-cultivation, about 12% of the callus explants produced hygromycin resistant calli on
MS medium supplemented with 2 mg l−1 2,4-D, 1 mg l−1 BA, 50 mg l−1 hygromycin, 500 mg l−1 cefotaxime after 8 weeks. Shoots were regenerated following transfer of the resistant calli to shoot induction medium containing
0.2 mg l−1 BA, 50 mg l−1 hygromycin, and 250 mg l−1 cefotaxime, and about 46% of the resistant calli differentiated into shoots. Finally, all the resistant shoots were rooted
on 1/2 MS media supplemented with 50 mg l−1 hygromycin, 250 mg l−1 cefotaxime. The transgenic nature of the transformants was demonstrated by the detection of β-glucuronidase activity in the primary transformants and by PCR and Southern hybridization analysis. About 5% of the total
inoculated callus explants produced transgenic plants after approximately 5 months. The procedure described will be useful
for both, the introduction of desired genes into Z. tenuifolia and the molecular analysis of gene function. 相似文献
19.
Zhang C Tao T Ying Q Zhang D Lu F Bie X Lu Z 《Applied microbiology and biotechnology》2012,94(4):949-958
In this study, the lipoxygenase (ana-LOX) gene from Anabaena sp. PCC 7120 was successful expressed and secreted in Bacillus subtilis. Under the control of the P43 promoter, with a signal peptide from the B. subtilis 168 nprB gene, and facilitated by the molecular chaperone PrsA, the production of the recombinant ana-LOX (ana-rLOX) reached
76 U/mL (171.9 μg/ml) in the supernatant. The purified ana-rLOX was investigated for its effect on dough protein. Ana-rLOX
treatment decreased free sulfhydryl groups, increased glutenin macropolymer content, promoted the formation of covalent bonds
between gluten protein, and affected protein crosslinking. The results indicated that large aggregates involving gliadin and
glutenin were formed. The glutenin macropolymer played a role in the formation of the dough network structure through the
exchange of thiol disulfide bonds and the formation of hydrogen or hydrophobic bonds with other proteins. 相似文献
20.