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1.
Underground water in volcanic areas contains vanadium when the basalt layer exists among igneous rocks. The concentration of vanadium in drinking water sometimes exceeds 0.8 μM in these areas, however, the physiological effects of vanadium, especially non-toxic effects, at concentrations lower than 1 μM are unknown. In the present experiments, we examined the effect of pentavalent vanadium and tetravalent vanadium at 0.8 and 8.0 μM concentrations on the recognition threshold to taste substances in healthy college students. Pentavalent vanadium, ammonium vanadate, lowered the sweet taste threshold to glucose at 0.8 and 8.0 μM as well. Tetravalent vanadium, vanadium sulfate, did not alter the threshold to glucose either at 8.0 μM or at 0.8 μM. Ammonium vanadate also decreased the sweet taste threshold to l-proline at 8.0 μM. Ammonium vanadate did not influence the sour taste threshold to hydrogen chloride. Neither ammonium sulfate nor ammonium bicarbonate altered the sweet taste threshold to glucose. Therefore, the effect of ammonium vanadate on the sweet taste threshold is attained by vanadium but not by ammonium. It was concluded that pentavalent vanadium at 0.8 μM intensifies the sweet taste sense to glucose rather specifically. We have first shown the physiological effect of vanadium at the concentration of the underground water level.  相似文献   

2.
In vitro culture establishment, shoot proliferation and ex vitro rooting responses of chokecherry (Prunus virginiana L.), `Garrington', and pincherry (P. pensylvanica L.f), `Mary Liss' and `Jumping Pound', were examined using various combinations of growth regulators. Dormant winter buds were used as explants. MSMO medium supplemented with 0.49 μM IBA and either 4.44 or 8.87 μM BA was found to be optimal for culture initiation of both species and cultivars. GA3 (28.89 μM) significantly reduced (p=0.0001) the number of successfully established cultures. BA concentrations 8.87–12.82 μM gave optimal shoot proliferation in chokecherry and 4.44 μM BA in both cultivars of pincherry. Auxin treatments were required for ex vitro rooting of approximately 10 mm long shoots in peat/perlite (1:1 v/v) mixture, at 25 °C, under mist. The best rooting (84%) was obtained with IBA/NAA (9.80/2.69 μM). A commercial rooting powder, Rootone F, containing IBA/NAA (0.057/0.067%) mixture, was also effective (75%). The ex vitro rooted plantlets did not require any additional acclimatization prior to transplanting to the regular greenhouse conditions. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

3.
Melaleuca alternifolia (tea tree) essential oil was investigated for its “in vitro” ability to control Trichoderma harzianum, a fungal contaminant that causes extensive losses in the cultivation of Pleurotus species. The antifungal activity of M. alternifolia essential oil and antagonist activities between Pleurotus species against three T. harzianum strains were studied in dual-culture experiments on an agar-based medium in which different concentrations of essential oil were incorporated. M. alternifolia essential oil at a concentration of 0.625 μL/mL, inhibited T. harzianum mycelial growth by 5.9–9.0%, depending on the strain. At the same concentrations P. ferulae and P. nebrodensis stimulated mycelial growth by 5.2–8.1%. All strains of T. harzianum were antagonistic to the Pleurotus species in the control. When essential oil was added to the substrate cultural, the antagonistic activity of T. harzianum against the Pleurotus species was weak (0.0625 μL of essential oil) or non-existent (0.125 μL of essential oil). M. alternifolia essential oil could be an alternative to the synthetic chemicals that are currently used to prevent and control T. harzianum in mushroom cultivation.  相似文献   

4.
The formation of thionates (thiosulfate, trithionate and tetrahionate) during the reduction of sulfate or sulfite was studied with four marine and four freshwater strains of sulfate-reducing bacteria. Growing cultures of two strains of the freshwater species Desulfovibrio desulfuricans formed up to 400 M thiosulfate and 100 M trithionate under conditions of electron donor limitation. Tetrathionate was observed in lower concentrations of up to 30 M. Uncoupler-treated washed cells of the four freshwater strains formed thiosulfate and trithionate at low electron donor concentrations with sulfite in excess. In contrast, only one of four marine strains formed thionates. The freshwater strain Desulfobulbus propionicus transformed sulfite almost completely to thiosulfate and trithionate. The amounts produced increased with time, concentration of added sulfite and cell density. Tetrathionate was detected only occasionally and in low concentrations, and was probably formed by chemical oxidation of thiosulfate. The results confirm the diversity of the sulfite reduction pathways in sulfate-reducing bacteria, and suggest that thiosulfate and trithionate are normal by-products of sulfate reduction.Abbreviations CCCP carbonyl cyanide m-chlorophenylhydrazone  相似文献   

5.
Summary Methyl jasmonate (MeJA) interacted significantly with both indole-3-acetic acid (IAA) and 6-benzylaminopurine (BA) to influence cell growth of cultured Onosma paniculatum cells. Cell growth decreased with increasing concentrations of MeJA from 0.004–4.45 μM with or without IAA and BA. The same concentrations of MeJA (0–4.45 μM) increased the cell growth with IAA and BA, when administered to the cultured cells in M9 medium. This was found to enhance the production of shikonin. The optimum time for MeJA addition for enhanced shikonin formation was 4 d after cell inoculation in M9 medium. Furthermore, shikonin formation was affected significantly by both MeJA/IAA and MeJA/BA combinations. Shikonin content was enhanced by increasing MeJA concentrations with IAA concentrations in the range of 0–28 μM and with BA concentrations in the range of 0–44.38 μM in MeJA/BA experiments, respectively. The optimal combination of MeJA and IAA was 4.45 μM and 0.28 μM, while MeJA and BA concentrations of 4.45 μM and 2.22 μM were optimal for shikonin formation. The result also showed that MeJA increased phenylalanine ammonia-lyase (PAL) and p-hydroxybenzoic acid-geranyltransferase (PHB-geranyltransferase) activites during the course of shikonin formation, but decreased the activity of PHB-O-glucosyltransferase within 9 d after inoculation. These results suggest that enhanced shikonin formation in cultured Onosma paniculatum cells induced by MeJA involves regulation of the key enzyme activities.  相似文献   

6.
In this study, the effects of inositol addition on expression of the MAL gene encoding maltase and phosphatidylinositol (PI) biosynthesis in Schizosaccharomyces pombe (a naturally inositol-requiring strain) were examined. We found that specific maltase activity was at its maximum when the concentration of added inositol reached 6 μg ml−1 in a synthetic medium containing 2.0% (w/v) glucose. When the concentration of added inositol was 1 μg ml−1 in the medium, repression of MAL gene expression occurred at glucose concentration higher than 0.2% (w/v). However, when S. pombe was cultured in the synthetic medium containing 6 μg ml−1, repression of maltase gene expression occurred only at initial glucose concentration above 1.0% (w/v). More mRNA encoding maltase was detected in the cells grown in the medium with 6 μg ml−1 inositol than in those grown in the same medium with 1 μg ml−1 inositol. These results demonstrate that higher inositol concentrations in the synthetic medium could derepress MAL gene expression in S. pombe. PI content of the yeast cells grown in the synthetic medium with 6 μg ml−1 of inositol was higher than that of the yeast cells grown in the same medium with 1 μg ml−1 of inositol. This means that PI may be involved in the derepression of MAL gene expression in S. pombe.  相似文献   

7.
Trichloroethylene (TCE) is an environmental contaminant provoking genetic mutation and damages to liver and central nerve system even at low concentrations. A practical scheme is reported using toluene as a primary substrate to revitalize the biofilter column for an extended period of TCE degradation. The rate of trichloroethylene (TCE) degradation byPseudomonas putida F1 at 25°C decreased exponentially with time, without toluene feeding to a biofilter column (11 cm I.D.×95 cm height). The rate of decrease was 2.5 times faster at a TCE concentration of 970 μg/L compared to a TCE concentration of 110 μg/L. The TCE itself was not toxic to the cells, but the metabolic intermediates of the TCE degradation were apparently responsible for the decrease in the TCE degradation rate. A short-term (2 h) supply of toluene (2,200 μg/L) at an empty bed residence time (EBRT) of 6.4 min recovered the relative column activity by 43% when the TCE removal efficiency at the time of toluene feeding was 58%. The recovery of the TCE removal efficiency increased at higher incoming toluene concentrations and longer toluene supply durations according to the Monod type of kinetic expression. A longer duration (1.4∼2.4 times) of toluene supply increased the recovery of the TCE removal efficieny by 20% for the same toluene load.  相似文献   

8.
Effects of anti-microbule drugs on tubulin polymerizationin vitro were investigated using purified mung bean (Vigna radiata) tubuli. Colchicine induced the formation of macrotubules at the relatively low concentration of 10 μM. and the appearance of corkscrew-like filaments from the ends of the macrotubules at concentrations of more than 100 μM. Vinblastine substantially inhibited polymerization at 1 μM and caused the formation of paracrystals at concentrations greater than 10 μM. Oryzalin inhibited polymerization at 1 μM partially and at 10 μM completely. Paracrystal formation was also induced by cremart at 10 μM, but these paracrystals appeared to be more rigid than those induced by vinblastine. Amiprophos methyl (APM), with a chemical configuration similar to cremart, substantially inhibited polymerization at 1 μM, but the formation of paracrystals was weak. Griseofulvin at 10 μMalso inhibited the polymerization of tubulin while at higher concentrations aggregates of helices were formed. Inhibition of polymerization by phenylcarbamate herbicides was more effective than that caused by benzimidazoylcarbamate fungicides. The effects of drugs onin vitro preformed (MTs) were also investigated. Colchicine and vinblastine showed identical effects to those on the polymerization process. Griseofulvin, cremart and APM induced only macrotubule formation while the other drugs tested had no major effects  相似文献   

9.
The potential on N-vanillylnonanamide (NVN) in preventing the attachment of Pseudomonas stutzeri and a Bacillus cereus-group strain was investigated. NVN up to 852 μM was not toxic, nor was it an energy source for either organism. Microbial attachment assays were carried out on glass and polylysine slides. with NVN being dispersed in or applied to the surfaces using a polyurethane coating. NVN at 205 μM inhibited Bacillus adhesion on glass slides by 48% and the percentage did not significantly increase at 852 μM. NVN blended into or sprayed onto the coating at 205 μmol/kg did not prevent adhesion. The compound is therefore not useful as an antifouling product under the tested coating conditions.  相似文献   

10.
The influence of toluene concentration on the specific growth rate, cellular yield, specific CO2, and metabolite production by Pseudomonas putida F1 (PpF1) was investigated. Both cellular yield and specific CO2 production remained constant at 1.0 ± 0.1 g biomass dry weight (DW) g−1 toluene and 1.91 ± 0.31 g CO2 g−1 biomass, respectively, under the tested range of concentrations (2–250 mg toluene l−1). The specific growth rate increased up to 70 mg toluene l−1. Further increases in toluene concentration inhibited PpF1 growth, although inhibitory concentrations were far from the application range of biological treatment processes. The specific ATP content increased with toluene concentration up to toluene concentrations of 170 mg l−1. 3-Methyl catechol (3-MC) was never detected in the cultivation medium despite being an intermediary in the TOD pathway. This suggested that the transformation from toluene to 3-MC was the limiting step in the biodegradation process. On the other hand, benzyl alcohol (BA) was produced from toluene in a side chain reaction. This is, to the best of our knowledge, the first reported case of methyl monoxygenation of toluene by PpF1 not harboring the pWW0 TOL plasmid. In addition, the influence of 3-MC, BA, and o-cresol on toluene degradation was investigated respirometrically, showing that toluene-associated respiration was not significantly inhibited in the presence of 10–100 mg l−1 of the above-mentioned compounds.  相似文献   

11.
Various factors affect the induction of somatic embryogenesis in peach palm (Bactris gasipaes Kunth). Among these, both the type and level of auxins had the greatest influence on in vitro responses, although the genotype and the developmental stage of the explants also influenced results. Younger inflorescences were more competent to respond to SE induction than more mature inflorescences and the use of a pre-treatment with 2,4-D (200 μM) in liquid MS culture medium also increased the embryogenic capacity, and diminished the development of flower buds. Higher oxidation rates were observed in explants maintained on 2,4-D-supplemented culture medium, while on 300 μM or 600 μM Picloram and Dicamba lower oxidation rates were observed. The progression from floral meristem to flower bud occurred at high frequency when low concentrations of auxins were used, independent of the type. Higher concentrations of Picloram or Dicamba reduced or even inhibited flower bud development. Picloram also enhanced the embryogenic induction rate more than 2,4-D and Dicamba, and among the concentrations evaluated 300 μM Picloram enhanced induction for both genotypes, with significant differences between genotypes. The best combination of variables used the least mature inflorescence (Infl1) from genotype I with the 2,4-D pre-treatment and 300 μM Picloram to generate 5 embryogenic calli from 18 explants; 26 embryos were obtained on average from each embryogenic callus. From these, eighteen embryos converted to plantlets and six of these survived transfer to the greenhouse.  相似文献   

12.
Ali MB  Hahn EJ  Paek KY 《Plant cell reports》2006,25(10):1122-1132
Roots of Panax ginseng exposed to various concentrations of Cu (0.0, 5, 10.0, 25.0, and 50.0 μM) accumulated high amounts of Cu in a concentration-dependent and duration-dependent manner. Roots treated with 50 μM Cu resulted in 52% and 89% growth inhibition after 20 and 40 days, respectively. Saponin synthesis was stimulated at a Cu concentration between 5 and 25 μM but decreased at 50 μM Cu. Malondialdehyde content (MDA), lipoxygenase activity (LOX), superoxide ion (O2 •−) accumulation, and H2O2 content at 5 and 10 μM Cu-treated roots were not increased but strongly increased at 50 μM Cu resulting in the oxidation of ascorbate (ASC) and glutathione (GSH) to dehydroascorbate (DHA) and glutathione disulfide (GSSG), respectively indicating a clear oxidative stress. Seven well-resolved bands of superoxide dismutase (SOD) were detected in the gel and an increase in SOD activity seemed to be mainly due to the induction of Fe-SOD 3. Five to 10 μM Cu slightly induced activity of ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR), guaiacol peroxidase (G-POD) but inhibited monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR) enzyme activities. No changes in catalase (CAT) activity and in activity gel were found up to 25 μM Cu, but both G-POD and CAT activities were inhibited at 50 μM Cu. Glutathione metabolism enzymes such as γ-glutamylcysteine synthetase (γ-GCS), glutathione-S-transferase (GST), and glutathione peroxidase activities (GPx) were activated at 5 and 10 μM Cu but were strongly inhibited at 50 μM Cu due to the Cu accumulation in root tissues. The strong depletion of GSH at 50 μM Cu was associated to the strong induction of γ-glutamyltranspeptidase (γ-GGT) activity. These results indicate that plant could grow under Cu stress (5–25 μM) by modulating the antioxidant defense mechanism for combating Cu induced oxidative stress.  相似文献   

13.
Yeast alcohol dehydrogenase (EC 1.1.1.1) catalyzes the novel reduction of p-nitro-so-N,N-dimethylaniline with NADH as a cofactor. Apparent kinetic constants for this enzymatic reaction are: V 2=2.1 s–1, K Q=456 M, K iQ=119 M, and K P=1.47 mM, at pH 8.9, 25 °C. This reaction is especially useful for the quantitative determination of NAD+ and NADH by enzymatic cycling.  相似文献   

14.
In this study we have examined the effects of individual gasoline hydrocarbons (C5–10,12,14 n-alkanes, C5–8 isoalkanes, alicyclics [cyclopentane and methylcyclopentane] and BTEX compounds [benzene, toluene, ethylbenzene, m-, o-, and p-xylene]) on cometabolism of methyl tertiary butyl ether (MTBE) and tertiary butyl alcohol (TBA) by Mycobacterium austroafricanum JOB5. All of the alkanes tested supported growth and both MTBE and TBA oxidation. Growth on C5–8 n-alkanes and isoalkanes was inhibited by acetylene whereas growth on longer chain n-alkanes was largely unaffected by this gas. However, oxidation of both MTBE and TBA by resting cells was consistently inhibited by acetylene, irrespective of the alkane used as growth-supporting substrate. A model involving two separate but co-expressed alkane-oxidizing enzyme systems is proposed to account for these observations. Cyclopentane, methylcyclopentane, benzene and ethylbenzene did not support growth but these compounds all inhibited MTBE and TBA oxidation by alkane-grown cells. In the case of benzene, the inhibition was shown to be due to competitive interactions with both MTBE and TBA. Several aromatic compounds (p-xylene > toluene > m-xylene) did support growth and cells previously grown on these substrates also oxidized MTBE and TBA. Low concentrations of toluene (<10 μM) stimulated MTBE and TBA oxidation by alkane-grown cells whereas higher concentrations were inhibitory. The effects of acetylene suggest strain JOB5 also has two distinct toluene-oxidizing activities. These results have been discussed in terms of their impact on our understanding of MTBE and TBA cometabolism and the enzymes involved in these processes in mycobacteria and other bacteria.  相似文献   

15.
Multiple Shoot Regeneration from Immature Embryo Explants of Papaya   总被引:1,自引:1,他引:0  
A simple and rapid method for multiple shoot formation in vitro from immature embryo axis explants of Carica papaya L. cvs. Honey Dew, Washington and Co2 is described. Multiple shoot regeneration was achieved by culture of the explants on modified Murashige and Skoog (MS) medium supplemented either with thidiazuron (TDZ; 0.45–22.7 μM) or a combination of benzylaminopurine (BAP; 0.2 – 8.84 μM) and naphthalene acetic acid (NAA; 0.5 – 2.64 μM). Highest frequency of shoot regeneration occurred on medium supplemented either with 2.25 μM TDZ or a combination of BAP (4.4 μM) and NAA (0.5 μM). Composition of the basal media influenced the frequency of multiple shoot initiation. Stunted shoots regenerated at 4.5 μM and higher concentrations of TDZ. Such shoots could, however, be elongated by transfer to medium containing 5.7 μM GA3. Rooting of the regenerated shoots was achieved in presence of indolebutyric acid (IBA; 4.92 – 19.68 μM), however, least response was in presence of 14.7 μM IBA. Rooted plants were hardened and transferred to pots. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

16.
Dietary chromium(III) picolinate (CrPic) effects on circulating steroid hormones have been reported in various experimental animals. However, direct effects of CrPic on adrenocortical steroidogenesis are uncertain. Therefore, the objective was to determine the effects of CrPic on cortisol and dehydroepiandrosterone sulfate (DHEAs) secretion from H295R cells. In experiment 1, a 24-h exposure to CrPic (0 to 200 μM) had both linear (p < 0.001) and quadratic (p < 0.001) effects on cortisol secretion from forskolin-stimulated cells with the highest cortisol secretion at 0.1 μM of CrPic and the lowest at 200 μM of CrPic. In experiment 2, a 48-h exposure to CrPic (200 μM) decreased cortisol (p < 0.07) release from forskolin-stimulated cells during a 24-h collection period. In experiment 3, a 48-h exposure to CrPic (100 μM) decreased cortisol (p < 0.05) and DHEAs (p < 0.01) from forskolin-stimulated cells during a 24-h sampling period. In experiment 4, a 24-h exposure to forskolin followed by a 24-h exposure to both forskolin and CrPic (100 and 200 μM) decreased both cortisol and DHEAs secretion (p < 0.01). This study suggests that at high concentrations, CrPic inhibits aspects of steroidogenesis in agonist-stimulated adrenocortical cells.  相似文献   

17.
A suitable protocol for micropropagation of Casuarina hybrid, Casuarina equisetifolia L. × Casuarina glauca Sieber ex Spreng (C. e. × C. g.), was developed. When seeds without seed coats were cultured on 4 germination media, the optimal seed germination percentage (91%) was obtained on 0.8% agar solidified water medium. Shoot multiplication was achieved by culturing 2-cm long epicotyls, excised from germinated seedlings, on MS (Murashige and Skoog 1962) basal medium supplemented with BA (6-benzylaminopurine) at 4.4, 8.8, 17.8 and 35.6 μM. The greatest percentage of axillary bud sproutings (87.5%), mean number of sprouts per explant (3.8), and shoot length (3.2 cm) were achieved on MS medium supplemented with 17.8 μM BA. MS medium supplemented with 4 different concentrations of IBA (indole-3-butyric acid) (4.3, 8.7, 13.0 and 17.4 μM) were used for rooting of in vitro grown shoots. The highest rooting percentage (65.6%), mean number of roots per explant (2.5) and mean length of roots per explant (1.6 cm) was achieved at 13.0 μM IBA. Rooted shoots grew well after transfer to a substrate of peat and pinebark (7:3) in the greenhouse.  相似文献   

18.
Abscisic acid (ABA) modifies the hydraulic properties of roots by increasing root water flux (Jv). The role of reactive oxygen species (ROS) in this ABA-induced process was evaluated. At the same time, some antioxidant enzyme activities in root tissues were measured. Phaseolus vulgaris plants were grown hydroponically, and different concentrations of ABA in combination with catalase enzyme or ascorbate were added to the nutrient solution. Catalase treatment had no effect by itself (no ABA) and had little or only a small stimulatory effect at ABA concentrations of 1, 50, and 100 μM, but it partially inhibited the ABA effect at 5 μM. Ascorbate by itself doubled Jv and root hydraulic conductance over the control value. In the presence of ABA, ascorbate partially or, at 100 μM, completely inhibited that ABA stimulation of Jv. These results are discussed in relationship to the possibility that ABA signaling in the roots involves ROS.  相似文献   

19.
K. Ohki 《Plant and Soil》1987,98(2):195-202
Summary Sorghum plants were grown in the greenhouse in modified Steinberg nutrient solution containing ten Al rates (0 to 297 μM) and harvested 28 days after transplanting. Top and root dry weight were not affected by added Al up to 74 μM; but decreased sharply at concentration of 148 μM and greater. Aluminum concentrations in blade 1 (recently matured blade) and plants remained constant from 0 to 297 μM added Al. Root Al concentration increased as added Al increased. No correlation existed between top dry weight and Al concentration in blade 1 or in plant. Root Al concentration was related to top dry weight and root dry weight to estimate the Al critical toxicity level. The Al critical toxicity levle in the root was 54 mmol kg−1 root dry weight basis for either top or root dry weight. In blade 1 Cu concentration negatively correlated with Al while Fe and P were positively correlated. In roots Ca, Mg, Mn and Fe concentrations were negatively correlated with Al while Zn, Cu, P, and K were positively correlated with Al concentration.  相似文献   

20.
Jin JK  Adams DO  Ko Y  Yu CW  Lin CH 《Mycopathologia》2004,158(3):369-375
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   

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