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1.
Benjamin Steinitz Nurit Barr Yona Tabib Yiftach Vaknin Nirit Bernstein 《Plant cell reports》2010,29(11):1315-1323
Plant regeneration and transformation in vitro is often improved by adding silver ion (Ag+) to the culture media as AgNO3 or silver thiosulfate (STS). Ag+ reacts with substances to form insoluble precipitates, while thiosulfate (S2O3
2−) interferes with these reactions. We studied the implications of silver precipitation and S2O3
2− in the medium for culture development by (1) examining formation of Ag+ precipitates from AgNO3 versus STS in agar gels and their possible dependence on agar type; (2) comparing Corymbia maculata culture responses to AgNO3 and STS and determining which better suits control of culture development; (3) clarifying whether STS-dependent alterations
in culture development are due to Ag+ alone or also to a separate influence of S2O3
2−. Silver precipitates appeared in aqueous gels of four agar brands supplemented with AgNO3, but not in Phytagel™, which remained transparent. No precipitation was observed in gels with STS. Indole-3-butyric acid (IBA)-mediated adventitious
root induction and shoot growth were higher in C. maculata shoot tips cultured on gels with STS versus AgNO3 (6–25 μM Ag+). IBA-treated shoot tips exhibited enhanced adventitious root regeneration, accelerated root elongation, increased frequency
of lateral root formation, and stimulated shoot growth mediated by 100–250 μM sodium thiosulfate (Na2S2O3) in medium without Ag+. The potency of S2O3
2− in facilitating culture development has never been recognized. It is inferred that superiority of STS in stimulating multiple
responses of C. maculata culture results from sustained biological activity of Ag+ through prevention of its precipitation, and from impact of S2O3
2− on cell differentiation and growth. 相似文献
2.
Wala Ghandour Julia A. Hubbard Janet Deistung Martin N. Hughes Robert K. Poole 《Applied microbiology and biotechnology》1988,28(6):559-565
Summary Growth of Escherichia coli in chloridefree medium in batch culture is inhibited completely at concentrations of AgNO3 greater than 2.5x10-6 M. Incubation of non-growing cells in HEPES buffer (pH 7.4) at increasing levels of Ag+ results in the progressive saturation of two types of binding site. At one site, the Ag+ is not released by washing with 0.1 M nitric acid, and is probably intracellular. Silver bound to the second site is released by acid-washing, but not by buffer washing, and is assumed to be surface-bound. The amounts of Ag+ taken up from solution at the two sites is 1.6x10-7 and 4.6x10-7 mol (mg dry weight)-1, respectively. Total accumulation of silver is 67 mg (g dry weight)-1, similar to literature values found for silver-resistant bacteria. Binding of Ag+ at intracellular sites (observed at low [Ag+]) appears to be independent of pH. Addition of AgNO3 to growing cells in mid-exponential phase of growth in concentrations that will inhibit growth results in substantially decreased accumulation of silver. Growth yield in chemostat culture is diminished in the presence of added Ag+, but this effect is moderated by added Cu2+, which may protect copper sites from Ag+ or compete with Ag+ for other sites at which Ag+ exerts toxic effects. Very small amounts of Cu2+ are found in cell samples from the chemostat compared to the substantial amounts of Ag+ taken up, but uptake of Cu2+ is decreased at higher [Ag+]/[Cu2+]ratios. 相似文献
3.
Microcuttings of easy-to-root dwarf rose cv. Starina, showing early symptoms of leaf senescence and shoot-tip necrosis in rooting stage, were chosen for the study. The
effects of inhibitors of ethylene biosynthesis (AOA, AIB) and action (AgNO3), and Ca2+ and Mg2+ were studied in relation to rooting, leaf senescence and shoot-tip necrosis. The effects of these substances were examined
with respect to IAA presence in a medium, which stimulated leaf yellowing and shoot-tip necrosis. AOA strongly inhibited rooting
of microcuttings, but did not affect ethylene biosynthesis. AIB at 250 mg·l−1 and AgNO3 2.5 mg·l−1 in the presence of IAA did not affect rooting but effectively prevented leaf senescence. Ca2+ alone or combined with Mg2+ at raised concentration, or an ethylene action inhibitor Ag+, reduced shoot-tip necrosis in microcuttings treated with IAA. Addition of Ag+ to IAA medium drastically increased ethylene production by the shoots. Interaction between endogenous levels of auxin, ethylene
and calcium in relation to rooting, shoot-tip necrosis and leaf senescence was discussed. Ethylene could enhance tissue sensitivity
to auxin. Moreover, the tissue of rose shoots is very sensitive in the in vitro condition on standard medium because of the calcium deficiency. Thus, the raised Ca/Mg level counteracted shoot-tip necrosis
through enhancing cell membrane and wall resistance to ethylene and IAA. 相似文献
4.
Nikhil H. Gokhale Seth Bradford J. A. Cowan 《Journal of biological inorganic chemistry》2007,12(7):981-987
[Cu2+•Cys-Gly-His-Lys] stimulates thermolysin (TLN) activity at low concentration (below 10 μM) and inhibits the enzyme at higher
concentration, with binding affinities of 2.0 and 4.9 μM, respectively. The metal-free Cys-Gly-His-Lys peptide also stimulates
TLN activity, with an apparent binding affinity of 2.2 μM. Coordination of copper through deprotonated imine nitrogens, the
histidyl nitrogen, and the free N-terminal amino group is consistent with the characteristic absorption spectrum of a Cu2+–amino-terminal copper and nickel binding motif (λ
max ∼ 525 nm). The lack of thiol coordination is suggested by both the absence of a thiol to Cu2+ charge transfer band and electrochemical studies, since the electrode potential (vs. Ag/AgCl) 0.84 V (ΔE = 92 mV) for the Cu3+/2+ redox couple obtained for [Cu2+•Cys-Gly-His-Lys] was found to be in close agreement with that of a related complex [Cu2+•Lys-Gly-His-Lys]+ (0.84 V, ΔE = 114 mV). The N-terminal cysteine appears to be available as a zinc-anchoring residue and plays a critical functional role
since the [Cu2+•Lys-Gly-His-Lys]+ homologue exhibits neither stimulation nor inhibition of TLN. Under oxidizing conditions (ascorbate/O2) the catalyst is shown to mediate the complete irreversible inactivation of TLN at concentrations where enzyme activity would
otherwise be stimulated. The observed rate constant for inactivation of TLN activity was determined as k
obs = 7.7 × 10−2 min−1, yielding a second-order rate constant of (7.7 ± 0.9) × 104 M−1 min−1. Copper peptide mediated generation of reactive oxygen species that subsequently modify active-site residues is the most
likely pathway for inactivation of TLN rather than cleavage of the peptide backbone. 相似文献
5.
Wen-Hao Chen Chun-Ming Xu Jian-Li Zeng Bing Zhao Xiao-Dong Wang Yu-Chun Wang 《World journal of microbiology & biotechnology》2007,23(10):1451-1458
At appropriate concentrations, polyamines promoted the callus growth and echinacoside content of Cistanche deserticola while Ag+ increased the content of echinacoside and acteoside. In a 20-day culture period, when putrescine (25 μM) and Ag+ (10 μM) were added on day 8 and day 16, respectively, the echinacoside production (1.7 g l−1) and acteoside production (0.4 g l−1) reached the maximum, which were 1.4-fold and 1.5-fold of those in single putrescine treatment, 1.6-fold and 1.4-fold of
those in single Ag+ treatment, respectively. Exogenous putrescine enhanced cell viability and antioxidant enzyme activity markedly, so increased
the final biomass. Ag+ addition increased H2O2 content and phenylalanine ammonia-lyase activity significantly which led to higher echinacoside and acteoside contents. 相似文献
6.
Federico A. Gutiérrez-Miceli Lourdes Arias Nicolás Juarez-Rodríguez Miguel Abud-Archila Aldo Amaro-Reyes Luc Dendooven 《In vitro cellular & developmental biology. Plant》2010,46(1):57-63
This paper reports on the optimum concentrations of naphthalene acetic acid (NAA) and 6-benzyladenine (BA) to stimulate callus
growth and NAA; kinetin and silver nitrate (AgNO3) for callus redifferentiation in Dianthus caryophyllus L. Meristems were excised and placed in MS medium with 30 g l−1 sucrose and 9.0 μM 2,4-d. Callus clusters were transferred to MS medium containing NAA (0, 1.7, 3.3, and 5.0 μM) and BA (0, 1.7, 3.3, and 5.0 μM)
for proliferation and to MS medium with 30 g l−1 sucrose, 2.5 g l−1 phytagel, kinetin (0, 33, and 66 μM); NAA (0, 7.95, and 15.9 μM) and AgNO3 (0, 23.54 and 47.08 μM) for shoot and root induction. Treatments were applied according to a Box–Behnken design. After callus
growth and redifferentiation, plants were incubated in the greenhouse at 18 ± 2°C for 4 wk and at 20–26°C for 4 wk. Finally,
plants were changed to near-commercial greenhouse conditions with different day (30–35°C) and night (16–24°C) temperatures.
Results showed better callus growth at higher NAA concentrations. A maximum callus weight was found with 5.0 μM NAA but without
BA. A maximum of 78% calluses with shoots was obtained with 15.9 μM NAA, 47.08 μM AgNO3, and 0.74 μM kinetin and 58% with roots with 15.7 μM NAA and 47.08 μM AgNO3, but without kinetin. The shoots obtained showed little hyperhydricity. Vigorous plants were obtained after gradual acclimatization
with an 80% survival rate under nursery conditions. 相似文献
7.
Y. K. Ip G. Q. Tan S. S. L. Kuah S. F. Chew 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(3):213-220
The capability of Phascolosoma arcuatum to detoxify sulfide in anaerobic conditions was examined. Sulfane sulfur, which underwent cold cyanolysis, was the major
excretory end product of sulfide detoxification during anoxia. Thiosulfate was not excreted into the external medium. Instead,
it was absorbed by P. arcuatum and its absorption was stimulated by the presence of sodium sulfide (Na2S) in the incubation medium. The effective formation and excretion of sulfane sulfur by P.␣arcuatum required the presence of both Na2S and sodium thiosulfate (Na2S2O3). Results obtained indicate that rhodanese might be involved in sulfide detoxification in this sipunculid. Rhodanese could
act as a catalyst in the transfer of sulfur atoms from thiosulfate to HS−. The body wall and the introvert were the main sites of sulfide detoxification. However, it is unlikely that epibiotic bacteria
associated with the outside surface of the worm were involved in the detoxification process. A time-course study on the contents
of thiosulfate and sulfane sulfur in the body wall of P. arcuatum incubated anaerobically in the presence of Na2S + Na2S2O3 verified that thiosulfate absorbed was utilized to detoxify sulfide to sulfane sulfur.
Accepted: 24 October 1996 相似文献
8.
The effects of ethylene inhibitors (silver nitrate – AgNO3 and silver thiosulphate – Ag2S2O3 as inhibitors of ethylene activity, cobalt chloride – CoCl2 as inhibitor of ethylene biosynthesis) and ethylene stimulator (aminocyclopropane-1-carboxylic acid – ACC) were studied on
the growth of cauliflower (Brassica oleracea L.) seedlings cultured in closed vessels (60 cm3). The addition of ethylene inhibitors have significant stimulatory effects on the growth and development of seedlings and
the effects were greatest with 10 μM AgNO3, the fresh weight of leaves was 2.6×, and the leaf area 2.8× those of the control (no additives). The effects of various
methods of ventilation (humidity-induced convective through-flow ventilation, diffusive ventilation and sealed condition)
on the growth and physiology of in vitrocauliflower seedlings were also investigated. The seedlings were cultured either in the presence or absence of AgNO3 (inhibitors of ethylene activity) and ACC (a precursor). Ethylene and CO2 levels in the head-space of the culture vessels were monitored. The humidity-induced through-flow ventilation system has
shown to be effective for improving growth, leaf chlorophyll content and the rate of net photosynthesis and preventing symptoms
of hyperhydricity, such as leaf epinasty, and franginess, reduction of leaf area etc. In contrast, the results also indicated
that the sealing of culture vessels could have serious inhibitory effects on growth and development, induce hyperhydricity
and reduce leaf chlorophyll content.
In the light period, CO2 depletion occurred in the head-space of the sealed vessels (ca. 40 μl l-1), the CO2 concentration increased with increasing efficiency of the ventilation. No ethylene accumulation was noticed in the head-space
of the culture vessels when humidity-induced throughflow ventilation was applied; however, high ethylene accumulation occurred
in sealed vessels.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
9.
At 10 mM, Cu+ was highly protective against killing of spores of Bacillus megaterium ATCC 19213 by H2O2, while at higher concentrations, from 15–100 mM, killing was augmented. In contrast, Cu2+, Fe2+, Fe3+, Co2+ or Co3+ ions acted only protectively. Cu+ itself was sporicidal in the absence of H2O2 or ascorbate, and its sporicidal action did not depend on generation of highly reactive oxygen species. It appeared that
killing involved either inhibition of germination or copper toxicity to germinated cells in that Cu+-inactivated spores did not germinate readily but chemical decoating of the cells prior to plating on a solid medium resulted
in reversal of the sporicidal effect.
Received 12 July 1996/ Accepted in revised form 03 November 1996 相似文献
10.
Summary
Debaryomyces hansenii (NCYC 459 and strain 75-21),Candida albicans (3153A),Saccharomyces cerevisiae (X2180-1B),Rhodotorula rubra (NCYC 797) andAureobasidium pullulans (IMI 45533 and ATCC 42371) were grown on solid medium supplemented with varying concentrations of AgNO3. Although Ag+ is highly toxic towards yeasts, growth on solid media was still possible at Ag concentrations of 1–2 mM. Further subculture on higher Ag concentrations (up to 5 mM) resulted in elevated tolerance. The extent of Ag tolerance depended on whether Ag-containing plates were exposed to light prior to inoculation since light-mediated reduction of Ag+ to Ag0 resulted in the production of a less toxic silver species. Experimental organisms exhibited blackening of colonies and the surrounding agar during growth on AgNO3-containing medium especially at the highest Ag concentrations tested. All organisms accumulated Ag from the medium; electron microscopy revealed that silver was deposited as electron-dense granules in and around cell walls and in the external medium. X-ray microprobe analysis indicated that these granules were metallic Ag0 although AgCl was also present in some organisms. Volatile and non-volatile reducing compounds were produced by several test organisms which presumably effected Ag+ reduction to Ag0. 相似文献
11.
Characteristics of non-specific permeability and H+-ATPase inhibition induced in the plasma membrane of Nitella flexilis by excessive Cu2+ 总被引:1,自引:0,他引:1
Effects of Cu2+ on a non-specific conductance and H+-ATPase activity in the plasma membrane of the freshwater alga Nitella flexilis L. Agardh was studied using a conventional microelectrode voltage-clamp technique. We show that a Cu2+-induced increase in the non-specific conductance is related to the formation of pores in the plasma membrane. Pore formation
is the result of unidentified chemical reactions, since the Q10 for the rate of increase of conductance over time was about 3. Various oxidants and antioxidants (10 mmol/l H2O2, 10 mmol/l ascorbate, 100 μg/ml superoxide dismutase, and 100 μg/ml catalase) did not alter Cu2+-induced changes in the plasma membrane conductance, suggesting that the effect of Cu2+ was unrelated to peroxidation of plasma-membrane lipids. In contrast, organic and inorganic Ca2+-channel antagonists (nifedipine, Zn2+, Cd2+, Fe2+, Ni2+) inhibited the Cu2+-induced non-specific conductance increase. This suggests that changes in Ca2+ influx underlie this effect of Cu2+. Decreasing the pH or the ionic strength of external solutions also inhibited the Cu2+-induced plasma-membrane conductance increase. Copper was also found to inhibit plasma-membrane H+-ATPase activity with half-maximal inhibition occurring at about 5–20 μmol/l and full inhibition at about 100–300 μmol/l.
The Hill coefficient of Cu2+ inhibition of the H+-ATPase was close to two.
Received: 8 December 1999 / Accepted: 16 August 2000 相似文献
12.
Masao Kitajima 《Photosynthesis research》1986,10(3):515-518
The photosynthetic sulfur bacterium, Chromatium
vinosum, was cultured in inorganic photographic processing solutions containing silver thiosulfate complex salt (AgNa3(S2O3)2) under light. It was found that Chromatium was resistant to Ag and accumulated granular silver in the membrane during growth. The amount of Ag accumulated in the cells depended on the initial concentrations of the Ag salt in the culture solution. When the concentration of Ag was 300 mg/l, the bacteria accumulated Ag as high as 30% of the dry cell weight. The size of the granules was 0.1 to 0.3 m. Results from X-ray microanalysis indicated that these granules consisted mostly of Ago with small fractions of Ag2S and AgCl. 相似文献
13.
Human β-mannosidase (MANB) was purified to homogeneity directly from lysosomes by using mannosamine conjugated magnetic (Fe3O4) nanoparticles, DE-52 cellulose, and sephadex G-200 chromatography. Fe3O4 nanoparticles were synthesized and utilized ammonia to attach the amino group on the nanoparticles. The particles were covalently
attached with D-mannosamine by cross linker glutaraldehyde and confirmed by FTIR spectroscopy. In FTIR analysis, the peaks
appeared at 2,356.6 cm−1 for −N = CH linkage and at 3,378.4 cm−1, 3,664.9 cm−1 for −OH groups confirmed the conjugation of D-mannosamine with Fe3O4 nanoparticles. Results showed a single band of 97 kDa of purified MANB in SDS-PAGE. The isoelectric point was 4.5 and the
Km and Vmax values were 2.51 mM and 0.315 μM/min/mg, respectively. The purification fold was 329 with 68% yield. The optimal activity
was at pH 5.0 and 75% activity was stable in 20% glycerol at 4°C. The enzyme activity was inhibited by Ni2+, Zn2+, Cd2+, Cu2+, Mo2+, Ag+1, iodoacetate, SDS, DMF, DMSO, ethanol, and acetone; slightly reduced by Pb2+, Co2+, EDTA, DTT, and β-mercaptoethanol. The activity was not affected by Mg2+, Mn2+, Sn2+, Ca2+, Fe3+, PMSF, Triton X-100, D-mannosamine, D-mannose, D-mannitol, D-glucose, and D-fructose. The homogeneity of MANB enzyme was
further confirmed by 2D-PAGE and immunoblot. This is the first novel report of conjugation of D-mannosamine with Fe3O4 nanoparticles for purification of human MANB enzyme. 相似文献
14.
Effects of Anions on the Capacity and Affinity of Copper Adsorption in Two Variable Charge Soils 总被引:2,自引:0,他引:2
Effects of nitrate,(NO3−) chloride (Cl−), sulfate (SO42-, and acetate (Ac−) on Cu2+ adsorption and affinity of the adsorbed Cu2+ were evaluated in two Fe and Al enriched variable charge soils from Southern China. The maximum adsorption of Cu2+ (M, a parameter from the Langmuir isotherm model) in the presence of different anions decreased in the order
Cl− > Ac− > NO3− > SO42- for both soils. The clayey loamy soil (mixed siliceous thermic Typic Dystrochrept, TTD), developed on the Arenaceous rock,
adsorbed less Cu2+ than the clayey soil (kaolinitic thermic Plinthudults, KTP), derived from the Quaternary red earths, regardless of anion
type present in the medium. The affinity of adsorbed Cu2+ to both soils could be characterized by the Kd (distribution coefficient) values and successive extraction of the adsorbed Cu2+ with 1-mol NH4Ac L−1. The log10Kd value was smaller for the TTD soil than for the KTP soil and decreased in the order of Cl− > NO3− > SO42- > Ac−
at low initial Cu2+ concentrations (≤40 mg Cu2+L−1), whereas at 80 mg Cu2+L−1, the log10Kd value was similar for NO3−, SO42-, and Ac−, but was slightly higher for Cl−. Complete extraction of Cu2+ adsorbed in the presence of Ac− was achieved. Influence of NO3− and SO42- on the affinity of adsorbed Cu2+ was similar, but the effects of Cl− depended on the initial Cu2+ concentrations. The extracted percentage of the adsorbed Cu2+ in the presence of NO3− or SO42- increased with increasing Cu2+ adsorption saturation. The presence of Cl−, NO3−, or SO42- markedly decreased the equilibrium solution pH for both soils with increasing initial Cu2+ concentrations, and the delta pH values at the highest Cu2+ level were 0.5, 0.63, and 0.55 U for the TTD soil and 0.79, 0.84, and 0.93 U for the KTP soil, respectively for the three
anions. The presence of Ac− had a minimal influence on the equilibrium solution pH because of the buffering nature of the NaAc/HAc medium which buffered
the released protons. The effects of anions on Cu2+ adsorption and affinity of the adsorbed Cu2+ were dependent on anion types and were apparently related to the altered surface properties caused by anion adsorption and/or
the formation of anion– Cu2+ complexes. 相似文献
15.
Yuki Ogura-Tsujita Hiroshi Okubo 《In vitro cellular & developmental biology. Plant》2006,42(6):614-616
Summary Shoot formation from rhizome explants of Cymbidium kanran was promoted on Murashige and Skoog (MS) medium: (1) with 1 mgl−1 (4.4μM) 6-benzyladenine (BA) and 0.1 mgl−1 (0.54μM) α-naphthaleneacetic acid (NAA); (2) with ethylene inhibitor (silver nitrate, AgNO3); or (3) by reducing ammonium nitrate (NH4NO3) and potassium nitrate (KNO3) to 25 and 50%, respectively, of their original concentrations. Shoot formation by BA and NAA was strongly inhibited with
the application of ethephon, an ethylene releaser. The ethylene production from the rhizome explants was reduced 30–55% on
low nitrogen medium after 1–3 mo. of culture and 52% on BA and NAA medium after 1 mo. of culture compared with explants on
standard MS medium. No difference in endogenous auxin (indole-3-acetic acid, IAA) and cytokinin (isopentenyl adenosine, iPA)
contents in the rhizomes was found between the treatments. Low ethylene levels were correlated with higher frequency of shoot
formation from the rhizomes. 相似文献
16.
An in situ study of photosynthetic oxygen exchange and electron transport rate in the marine macroalga Ulva lactuca (Chlorophyta) 总被引:5,自引:0,他引:5
Longstaff BJ Kildea T Runcie JW Cheshire A Dennison WC Hurd C Kana T Raven JA Larkum AW 《Photosynthesis research》2002,74(3):281-293
Direct comparisons between photosynthetic O2 evolution rate and electron transport rate (ETR) were made in situ over 24 h using the benthic macroalga Ulva lactuca (Chlorophyta), growing and measured at a depth of 1.8 m, where the midday irradiance rose to 400–600 μmol photons m−2 s−1. O2 exchange was measured with a 5-chamber data-logging apparatus and ETR with a submersible pulse amplitude modulated (PAM)
fluorometer (Diving-PAM). Steady-state quantum yield ((Fm′−Ft)/Fm′) decreased from 0.7 during the morning to 0.45 at midday, followed by some recovery in the late afternoon. At low to medium
irradiances (0–300 μmol photons m−2 s−1), there was a significant correlation between O2 evolution and ETR, but at higher irradiances, ETR continued to increase steadily, while O2 evolution tended towards an asymptote. However at high irradiance levels (600–1200 μmol photons m−2 s−1) ETR was significantly lowered. Two methods of measuring ETR, based on either diel ambient light levels and fluorescence
yields or rapid light curves, gave similar results at low to moderate irradiance levels. Nutrient enrichment (increases in
[NO3
−], [NH4
+] and [HPO4
2-] of 5- to 15-fold over ambient concentrations) resulted in an increase, within hours, in photosynthetic rates measured by
both ETR and O2 evolution techniques. At low irradiances, approximately 6.5 to 8.2 electrons passed through PS II during the evolution of
one molecule of O2, i.e., up to twice the theoretical minimum number of four. However, in nutrient-enriched treatments this ratio dropped to
5.1. The results indicate that PAM fluorescence can be used as a good indication of the photosynthetic rate only at low to
medium irradiances.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
17.
An efficient regeneration system for Phaseolus vulgaris was developed from mature seeds germinated on Murashige and Skoog (MS) medium supplemented with thidiazuron or N6-benzylaminopurine (BA) for 6 d. Using cotyledonary nodes, multiple buds were induced on the MS medium supplemented with 5.0
mg dm−3 BA with the induction frequency 71.9 % after 4-week culture. The buds were then transferred onto shoot formation medium containing
1.0 mg dm−3 BA, 0.1 mg dm−3 gibberellic acid and 2.0 mg dm−3 silver nitrate. The addition of AgNO3 enhanced the frequency of the shoot formation from 61.3 to 87.6 %. Root induction medium was half-strength MS medium with
0.75 mg dm−3 indolebutyric acid and 0.02 mg dm−3 BA. The average root frequency was 84.3 %. The regenerated plantlets with healthy roots grew successfully when transferred
to soil. Using this system we obtained over 10 regenerated plantlets from one explant. 相似文献
18.
Kerstin Hauschild Manfred K. Grieshaber 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(5):378-388
The lugworm Arenicola marina is a typical inhabitant of intertidal flats. In its L-shaped burrow the animal is exposed to varying concentrations of O2 and toxic sulfide depending on the tides. The lugworm is able to detoxify sulfide through its oxidation to thiosulfate. When
exposed to declining O2 tensions Arenicola marina reacted as an oxyconformer. In the presence of 25 μmol · l−1 sulfide the respiration was not affected. In contrast, the lugworm consumed significantly less O2 at any Po2 in the presence of 200 μmol · l−1 sulfide. Without sulfide anaerobic metabolism started at a Po2 of approximatedly 10 kPa. Even at high O2 tensions animals exposed to sulfide produced significantly more anaerobic metabolites compared with the controls. Accordingly
the critical value PcM, the ambient Po2 below which anaerobic metabolism starts, was shifted towards normoxia. Since O2 supply was sufficient for aerobic metabolism, anaerobiosis was induced by sulfide. An influx of sulfide was observed at 25
as well as at 200 μmol · l−1 sulfide. The main product of sulfide detoxification in the lugworm was thiosulfate. Its synthesis increased with ambient
Po2 and depended on the sulfide concentration. Sulfide and thiosulfate were detected in the coelomic fluid, the blood, and the
body wall of Arenicola marina. Only about 2% of the ambient O2 was used for sulfide detoxification at 25 μmol · l−1 sulfide and about 50% at 200 μmol · l−1 sulfide, respectively. Even at the low sulfide concentration Arenicola marina's capacity to detoxify sulfide was too low to maintain a complete aerobic metabolism.
Accepted: 19 February 1997 相似文献
19.
The toxicity of cadmium to barley plants as affected by complex formation with humic acid 总被引:3,自引:0,他引:3
An ‘alternating solution’ culture method was used to study the effects of chloride ions and humic acid (HA) on the uptake
of cadmium by barley plants. The plants were transferred periodically between a nutrient solution and a test solution containing
one of four levels of HA (0, 190, 569 or 1710 μg cm−3) and one of five levels of Cd (0, 0.5, 1.0, 2.5 or 5.0 μg cm−3) in either a 0.006M NaNO3 or 0.006M NaCl medium. Harvest and analysis of shoots and roots was after nineteen days. The distribution of Cd in the test solutions
between Cd2+, CdCl+ and HA-Cd was determined in a separate experiment by dialysis equilibrium.
In the nitrate test solutions Cd uptake was clearly controlled by Cd2+ concentration and was therefore reduced by HA complex formation. In the absence of HA, chloride suppressed Cd uptake indicating
that Cd2+ was the preferred species. However complex formation with Cl− enhanced uptake when HA was present because of an increase in the concentration of inorganic Cd species relative to the nitrate
system.
The ratio root-Cd/shoot-Cd remained at about 10 across a wide range of shoot-Cd concentrations, from about 3 μg g−1 (sub-toxic) up to 85 μg g−1 (80% yield reduction). The ability of the barley plants to accumulate ‘non-toxic’ Cd in their roots was thus very limited.
Humic acid also had no effect on Cd translocation within the plant and the root/shoot weight ratio did not vary with any treatment.
At shoot-Cd concentrations in excess of 50 μg g−1, K, Ca, Cu and Zn uptake was reduced, probably the result of root damage rather than a specific ion antagonism. The highest
concentration of HA also lowered Fe and Zn uptake and there was a toxic effect with increasing HA concentration at Cd=0. However
the lowest HA level, comparable with concentrations found in mineral soil solutions, only reduced yield (in the absence of
Cd) by <5% while lowering Cd uptake across the range of Cd concentrations by 66%–25%. 相似文献