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1.
The experimental enhancement of UV-B radiation resulted in damage to chlorophyll-a in Spirulina platensis 794, and the degree of this damage was modified by chemical treatments. The addition of 0.5 mM sodium nitroprusside (SNP),
a donor of nitric oxide (NO), to cultures of Spirulina platensis 794 could markedly alleviate the damage to chlorophyll-a caused by enhanced ultraviolet-B radiation. Exposure of N2-fixing cyanobacterium Spirulina platensis 794 to enhanced ultraviolet-B radiation resulted in an intensity-dependent inhibition of nitrogenase activity. In cultured
cells that were treated with 0.5 mM SNP and enhanced UV-B for 6 h, nitrogenase activity increased by 47.3% compared with UV-B
treated control cells. SNP apparently counteracted the decrease in nitrogenase activity caused by UV-B stress. NAC (a free
radical scavenger) significantly increased nitrogenase activity, but PTIO (a nitric oxide scavenger) decreased nitrogenase
activity in UV-B treated S. platensis 794. Thus, the free radical scavenger NAC and NO may counteract the effects of enhanced UV-B radiation. The activity of UV-B-inhibited
nitrogenase did not recover upon transfer of exposed cells to fluorescent light, suggesting that the inhibition may be due
to specific inactivation of the enzyme. By experimentally manipulating the inhibitors of photosystem-II activity, it was demonstrated
that nitrogenase activity in cyanobacterium S. platensis 794 is limited by the amount of reductant and ATP. This result further confirmed that nitrogenase activity requires a continued
and abundant supply of suitable reductant and ATP for conversion of N2 to NH3. The effects of UV-B treatment on nitratase activity were also examined, and enhanced UV-B radiation increased nitratase
activity. In addition, enhanced UV-B in combination with SNP and NAC resulted in significant increases in the activity of
nitratase. 相似文献
2.
一氧化氮对增强的UV_B胁迫下螺旋藻生物损伤的减缓作用 总被引:2,自引:0,他引:2
为了探讨一氧化氮对增强的UV-B胁迫下螺旋藻生物学特性的影响,通过色素含量、蛋白质含量和生物量3个方面的变化证实了0.5mmol/L的一氧化氮(Nitric oxide,NO)供体硝普钠(Sodium nitroprusside,SNP)对增强UV-B胁迫下的螺旋藻(Spirulina platensis)794细胞生物损伤有明显的减缓作用。实验结果显示,NO能够显著诱导增强的UV-B胁迫下螺旋藻细胞内蛋白质含量、脯氨酸含量的提高,促进正常生长条件下螺旋藻(Spirulina platensis)794细胞内抗氧化物质GSH含量的增多,但外源NO又可以降低增强UV-B胁迫下螺旋藻细胞中GSH含量的增加。说明NO对增强UV-B胁迫下的螺旋藻794细胞有保护作用,可以减轻UV-B胁迫对螺旋藻(S.platensis)细胞引起的生物损伤。首次研究报道了增强UV-B胁迫下NO信号分子对蓝细菌———螺旋藻细胞生物损伤调节能力的影响,为进一步探讨NO信号及其与其它信号分子之间相互作用、相互关联来调节细胞的生理生化过程,以减缓UV-B胁迫下的生物损伤机理奠定了基础。 相似文献
3.
Gangping Hao Xihua Du Faxing Zhao Renjiu Shi Jianmei Wang 《Plant Cell, Tissue and Organ Culture》2009,97(2):175-185
The role of nitric oxide (NO) in UV-B-induced secondary metabolite accumulation in Ginkgo biloba callus was investigated. Overall, UV-B irradiation induced multiple biological responses in callus of G. biloba, including increased both NO production and nitric oxide synthase (NOS) activity, and subsequent activation of phenylalanine
ammonium lyase (PAL) and synthesis of flavonoids. Application of NO via the donor sodium nitroprusside (SNP) enhanced UV-B-induced
PAL activity and increased accumulation of flavonoids in G. biloba callus. Both, the NOS inhibitor l-NAME (N (G)-nitro-l-arginine methyl ester) and the NO scavenger c-PTIO (2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) reduced the
production of NO. Moreover, UV-B-induced increase of PAL activity and flavonoid accumulation were suppressed by l-NAME and c-PTIO. These findings suggested a causal relationship between NO release and both PAL activity and flavonoid accumulation
under UV-B irradiation. In addition, it also indicated that NO, produced via NOS-like activity in ginkgo callus subjected
to UV-B irradiation, might act as an essential signaling molecule for triggering the activation of PAL and synthesis of flavonoids.
Additionally, a guanylyl cyclase inhibitor 6-anilino-5,8-quinolinequinone (LY-83583) prevented both UV-B- and SNP-induced
enhancement of PAL activation and flavonoid biosynthesis thus suggesting that the NO function was mediated by cyclic guanosine
5’-monophosphate. However, these effects of c-PTIO, l-NAME, and LY-83583 were partial, thus suggesting that there were NO-independent pathways in UV-B signaling networks.
Gangping Hao and Xihua Du are contributed equally to this article. 相似文献
4.
Salvia miltiorrhiza is one of the most popular traditional Chinese medicinal plants for treatment of coronary heart disease. Tanshinones are
the main biological active compounds in S. miltiorrhiza. In this study, effects of exogenous methyl jasmonate (MJ) and nitric oxide (NO) on tanshinone production in S. miltiorrhiza hairy roots were investigated and the roles of reactive oxygen species (ROS) in MJ and NO-induced tanshinone production were
elucidated further. The results showed that contents of four tanshinone compounds were significantly increased by 100 μM MJ
when compared to the control. Application of 100 μM sodium nitroprusside (SNP), a donor of NO, also resulted in a significant
increase of tanshinone production. Expression of two key genes encoding 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR)
and 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) was up-regulated by MJ and SNP. Generations of O2
− and H2O2 were triggered by MJ, but not by SNP. The increase of tanshinone production and up-regulation of HMGR and DXR expression induced by MJ were significantly inhibited by ROS scavengers, superoxide dismutase (SOD) and catalase (CAT). However,
neither SOD nor CAT was able to suppress the SNP-induced increase of tanshinone production and expression of HMGR and DXR
gene. In conclusion, tanshinone production was significantly stimulated by MJ and SNP. Of four tanshinone compounds, cryptotanshinone
accumulation was most affected by MJ elicitation, while cryptotanshinone and tanshinone IIA accumulation was more affected
by SNP elicitation. ROS mediated MJ-induced tanshinone production, but SNP-induced tanshinone production was ROS independent. 相似文献
5.
Yingli Yang Xueling Wei Ruxia Shi Qing Fan Lizhe An 《Journal of Plant Growth Regulation》2010,29(4):465-476
Little is known about the physiological adaptation mechanisms of the desert halophyte Nitraria tangutorum Bobr. to the environment. In this study, callus from Nitraria tangutorum Bobr. was used to investigate physiological responses to salinity and the regulatory function of nitric oxide (NO) on catalase
(CAT) activity. Increased dry weight and soluble proteins were observed in the callus exposed to lower salinity (50 and 100 mM
NaCl), whereas 200 mM NaCl led to significant decreases of these two growth parameters, and the levels of proline and soluble
carbohydrates also were enhanced under NaCl treatment. In addition, short-term stress from 50 mM NaCl and the application
of lower sodium nitroprusside (SNP, a NO donor) concentration resulted in decreased levels of malondialdehyde (MDA). In contrast,
higher concentrations of NaCl and SNP induced significant oxidative damage in Nitraria tangutorum Bobr. callus. Analysis based on the fluorescent probe DAF-FM DA revealed that NaCl and SNP treatment led to enhanced levels
of NO in the callus cells. Moreover, the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO)
reduced endogenous NO concentrations and abolished the enhancement in dry weight and the decrease in MDA level under 50-mM-NaCl
treatment. CAT activity increased under salt stress, and the 50-mM-NaCl effect was alleviated by treatment with c-PTIO or
the nitric oxide synthase inhibitor Nω-nitro-l-arginine. We suggest that Nitraria tangutorum Bobr. callus exhibited tolerance to lower-salinity stress. We also showed that increased NO generation in response to salinity
might be associated with regulation of growth, protection against oxidative damage, and excitation of CAT activity in Nitraria tangutorum Bobr. callus under salt stress. 相似文献
6.
The present study examined the possibility of increasing the contents of some bioactive compounds of Spirulina platensis cultivated in medium containing various hydrogen peroxide concentrations (2, 4, 6 and 8 mM) as a model for environmental
stress. A positive correlation was observed between the increase of H2O2 and increasing amounts of cellular lipophilic antioxidants (total carotenoids and α-tocopherol) and hydrophilic antioxidants
[glutathione (GSH) and ascorbic acid (AsA)]. HPLC profile of carotenoids revealed that algae responded to the change of H2O2 exposure by the accumulation of higher amounts of β-carotene, astaxanthine, luteine, zeaxanthin and cryptoxanthin. S. platensis showed significant linear increase in activities of antioxidant enzymes, i.e., catalase (CAT), peroxidase (PX), ascorbate
peroxidase (APX) and superoxide dismutase (SOD), with increasing H2O2 concentrations. A pronounced increase of oxidative lesions’ indexes [thiobarbituric acid reactive substances (TBARS) and
paramagnetic radical-EPR signal] was found in algal grown at 8 mM H2O2. These data revealed that S. platensis behaved with different strategies against H2O2 exposure which is dose dependent and their response strongly correlated with the scavenging enzymes (SOD, CAT, PX and APX)
and antioxidant compounds (GSH, AsA, β-carotene, astaxanthine and α-tocopherol) in the antioxidant defense systems. Therefore,
S. platensis could be considered as good candidates for successful cultivation in artificial open ponds under different environmental
conditions, as high value health foods, functional foods and as source of wide spectrum of nutrients. 相似文献
7.
UV-B induced stress responses in three rice cultivars 总被引:2,自引:0,他引:2
UV-B responses of three rice (Oryza sativa L.) cultivars (Sasanishiki, Norin 1 and Surjamkhi) with different photolyase activity were investigated. Carbon dioxide assimilation
data support that Sasanishiki was less sensitive to UV-B than Norin 1 and Surjamkhi. UV-B radiation sharply decreased the
content of Rubisco protein in Surjamkhi and has no effect in Sasanishiki. The photochemical activities of photosystem (PS)
1 and PS 2 was slightly affected by UV-B treatment. The content of H2O2 and the activities of antioxidant enzymes, catalase (CAT), peroxides (POX) and superoxide dismutase (SOD) were enhanced after
UV-B treatment. The activities of CAT and POX isoenzymes in Sasanishiki were more enhanced by UV-B radiation than those in
Norin 1 and Surjamkhi. 相似文献
8.
Cascade transduction and production of the light-nitric oxide signal from shoots to roots in maize seedlings exposed to enhanced UV-B radiation 总被引:1,自引:0,他引:1
The biomasses, rate of apparent nitric oxide (NO)-release, nitric oxide synthase (NOS) activity as well as β-d-endo and exo-glucanase activity of the cell wall were analyzed and determined in the roots of maize seedlings. It was found
that rhizospheric treatments of 2-phenyl-4,4,5,5-tetramethlimida-zoline-l-oxyl-3-oxide (PTIO), a NO scavenger, and radiation
of enhanced ultraviolet-B (UV-B) to aerial parts of the seedling markedly inhibited the rate of NO release in roots, raised
the activity of β-d-endo and exo-glucanase, and increased the biomasses of roots. The patent inhibitor, N-nitro-l-arginine (LNNA), of NOS was unable to inhibit NOS activity and NO generation. Inversely, reactive oxygen species (ROS) eliminator,
N-acetyl-cysteine (NAC), stimulated the rate of NO release. There is no relationship between NOS activity and the rate of NO
release. The latter showed a positive correlation with nitrate reductase (NR) activity, whereas it showed a negative correlation
with the bio-masses and the activity of β-d-endo and exo-glucanase. All results implicated that NO was a by-product generated by NR catalysis, whereas NR activity was
sensitively repressed by the systemic signal network (involved in ROS) induced by enhanced UV-B. It indicated that the downstream
signal molecule of enhanced UV-B light is probably ROS which decreased NO generation through inhibiting NR activity. The endogenous
NO generated by NR catalysis is perhaps such a messenger for restraining β-d-endo and exo-glucanase activity that the root growth was retarded. 相似文献
9.
Akihiro Kubo Mitsuko Aono Nobuyoshi Nakajima Hikaru Saji Kiyoshi Tanaka Noriaki Kondo 《Journal of plant research》1999,112(3):279-290
Arabidopsis thaliana . Three-week-old plants were exposed to a high temperature (30 C), an enhanced light intensity (200 μE/m2/sec), water deficiency (water deprivation for 2 days), a chilling temperature (5 C), or ultraviolet-B (UV-B) radiation (0.25
or 0.094 W/m2) for 1 week (except for water deficiency). The high temperature and enhanced light treatments increased only dehydroascorbate
reductase (DHAR) activity. Water deficiency enhanced the activities of DHAR and guaiacol peroxidase (PER). Chilling temperature
increased the activities of ascorbate peroxidase (APX) and glutathione reductase (GR), whereas it decreased catalase (CAT)
activity. UV-B at an intensity of 0.25 W/m2 elevated the activities of APX, monodehydroascorbate reductase (MDHAR), GR, PER and superoxide dismutase (SOD). It was suggested
that the amounts of phenylpropanoid compounds increased during treatments of plants with enhanced light intensity, chilling
temperature, and UV-B. These results suggest that some differences exist among the oxidative stress conditions caused by the
different treatments, although all of these treatments seem to be related to active oxygen production. We propose that in
A. thaliana, environmental stresses may be classified into those which induce DHAR activity and those which induce APX activity.
Received 11 January 1999/ Accepted in revised form 22 April 1999 相似文献
10.
Yi-Ping Chen 《Plant Growth Regulation》2008,55(1):73-79
Sterilized seeds of Isatis indigotica (Brassicacae) were divided into four groups based on irradiation pretreatments. These control groups (C) were non irradiated,
He–Ne laser treated seeds (L), UV-B treated seeds (B) and He–Ne laser followed by UV-B radiation treated seeds (LB). Laser
radiation was provided by He–Ne laser, UV-B radiation was provided by filtered Qin brand 30 W fluorescent sun lamps. Malondialdehyde
(MDA), proline, UV-B absorbing compounds and ascorbic acid (AsA) concentrations, as well as, the activities of superoxide
dismutase (SOD), catalase (CAT) and peroxidase (POD) were measured in the cotyledons of seedlings from all the four irradiation
treatments. The result indicate that UV-B radiation enhanced the concentration of MDA while decreasing the activities of SOD,
CAT, POD and the concentration of AsA in the seedlings compared with the controls. The concentration of MDA decreased, while
the activities of SOD, CAT, POD and the concentration of AsA increased in seedling treated with He–Ne laser and UV-B compared
to UV-B alone. The concentration of proline and UV absorbing compounds increased progressively with treatments i.e. UV-B irradiation,
He–Ne laser irradiation, and He–Ne laser irradiation followed by UV-B irradiation compared to the controls. The present data
suggest that Isatis indigotica seedlings derived from laser stimulated seeds showed improved resistance to elevated UV-B. 相似文献
11.
The effects of nitric oxide (NO) on spore germination of Penicillium expansum were investigated and a possible mechanism was evaluated. The results indicated that NO released by sodium nitroprusside
(SNP) significantly suppressed fungal growth. With the use of an oxidant sensitive probe and Western blot analysis, an increased
level of intracellular reactive oxygen species (ROS) and enhanced carbonylation damage were detected in spores of P. expansum under NO stress. Exogenous superoxide dismutase (SOD) and ascorbic acid (Vc) could increase the resistance of the spore to
the inhibitory effect of NO. The activities of SOD and catalase (CAT), as well as ATP content in spores under NO stress were
also lower than those in the control. We suggest that NO in high concentration induces the generation of ROS which subsequently
causes severe oxidative damage to proteins crucial to the process of spore germination of P. expansum. 相似文献
12.
Impact of ultraviolet-B (UV-B) and Cd, applied individually and in combination, measured in terms of oxygen-evolution, chlorophyll
(Chl) and protein contents, lipid peroxidation, and enzymatic and non-enzymatic antioxidants of Anabaena doliolum, revealed a greater oxidative damage induced by UV-B than by Cd. While superoxide dismutase (SOD) showed a greater stimulation
by UV-B than Cd, the activities of catalase (CAT) and glutathione reductase (GR) declined after UV-B treatment. Cd treatment,
however, enhanced the activities of ascorbate peroxidase (APX) and GR. CAT activity increased at low but decreased at high
dose of Cd. Increase in carotenoid (Car) content in UV-B treated cells suggested a shielding effect of Car against UV-B stress.
A 15-and 10-fold rise in α-tocopherol (α-TOC) content at high dose of Cd and/or UV-B offered testimony to the antioxidant
role of α-TOC. 相似文献
13.
The adaptive and cross-protection responses to oxidants were investigated in Bacillus sp. F26. The cells were treated with sublethal concentrations of either H2O2 or menadione (a superoxide-generating agent) to induce an adaptive response. The results showed that the cells treated with
menadione exhibited cross-protection against, but in another case, those cells treated with H2O2 did not show significant resistance to menadione. It suggests that Bacillus sp. F26 possesses two separate adaptive responses that respond to the two different kinds of oxidants. The adaptability is
regarded as that which is accompanied by the inductions of some antioxidant enzymes. It was found that catalase (CAT) production
was increased about 1.6-fold after treatment with 600 μM H2O2, whereas the presence of 50 μM menadione induced CAT, superoxide dismutase (SOD), glucose-6-phosphate dehydrogenase (G6PD), and glutathione reductase (GR)
by 2-, 2-, 2-, and 1.6-fold, respectively. The results can be used to explain why menadione-treated cells have higher adaptability
to lethal concentrations of oxidants than that of those H2O2-treated. In addition, it was found that growing Bacillus sp. F26 in high-salinity media causes it to become more resistant to H2O2 and menadione stress, which may be partially due to the induction of CAT and SOD production under high NaCl concentration. 相似文献
14.
Regio- and Stereo-selective Hydroxylation of Abietic Acid Derivatives by Mucor circinelloides and Mortierella isabellina 总被引:4,自引:0,他引:4
Mucor circinelloides and Mortierella isabellina hydroxylated dehydroabietic acid (DehA). DehA was converted regio- and stereo-selectively by whole cells of Mr. circinelloides to give 2α-hydroxydehydroabietic acid in a 75% molar conversion yield (11 mM from 14.7 mM DehA) after 72 h in the cultivation medium containing 3% (v/v) Tween 80. With cells of Ma. isabellina, under the same conditions, 20.5 mM (6.5 g l−1) 2–hydroxydehydroabietic acid (α/β=81/19) was formed from 26.4 mM DehA. 相似文献
15.
Yi-Ping Chen 《Plant signaling & behavior》2009,4(7):571-573
To determine the response of antioxidant defense system to laser radiation apical meristem of Isatis indigotica seedlings, Isatis indigotica seedlings were subjected to UV-B radiation (10.08 kJ m−2) for 8 h day−1 for 8 days (PAR, 220 µmol m−2 s−1) and then exposed to He-Ne laser radiation (633 nm; 5.23 mW mm−2; beam diameter: 1.5 mm) for 5 min each day without ambient light radiation. Changes in free radical elimination systems were measured, the results indicate that: (1) UV-B radiation enhanced the concentration of Malondialdahyde (MDA) and decreased the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in seedlings compared with the control. The concentration of MDA was decreased and the activities of SOD, CAT and POD were increased when seedlings were subjected to elevated UV-B damage followed by laser; (2) the concentration of UV absorbing compounds and proline were increased progressively with UV-B irradiation, laser irradiation and He-Ne laser irradiation plus UV-B irradiation compared with the control. These results suggest that laser radiation has an active function in repairing UV-B-induced lesions in seedlings.Key words: Isatis indigotica, laser, UV-B lesion 相似文献
16.
Nitric oxide (NO) is a component of the repertoire of signals implicated in plant responses to environmental stimuli. In the
present study, we investigated the effects of exogenous application of NO-releasing donor sodium nitroprusside (SNP) and nitric
oxide synthase inhibitor N
G-nitro-l-arginine-methyl ester (l-NAME) on dehydration and drought tolerance of Poncirus trifoliata. The endogenous NO level was enhanced by SNP pretreatment, but decreased by l-NAME, in the hydroponic or potted plants with or without stresses. Under dehydration, leaves from the SNP-treated hydroponic
seedlings displayed less water loss, lower electrolyte leakage and reactive oxygen species accumulation, higher antioxidant
enzyme activities and smaller stomatal apertures as compared with the control (treated with water). In addition, pretreatment
of the potted plants with SNP resulted in lower electrolyte leakage, higher chlorophyll content, smaller stomatal conductance
and larger photosynthetic rate relative to the control. By contrast, the inhibitor treatment changed these physiological attributes
or phenotypes in an opposite way. These results indicate that NO in the form of SNP enhanced dehydration and drought tolerance,
whereas the inhibitor makes the leaves or plants more sensitive to the stresses. The stress tolerance by NO might be ascribed
to a combinatory effect of modulation of stomatal response and activation of the antioxidant enzymes. Taken together, NO is
involved in dehydration and drought tolerance of P. trifoliata, implying that manipulation of this signal molecule may provide a practical approach to combat the environmental stresses. 相似文献
17.
Ultraviolet-B (UV-B) radiation to thylakoid membrane and fatty acid profile has been investigated in cyanobacterium, Spirulina platensis. The thylakoid membrane was isolated by mechanical disruption of the freeze-dried and lysozyme-treated cells followed by
differential density gradient centrifugation and morphological variations were examined. UV radiation distorted the membrane
on the outer side with reduced chlorophyll a (chl a) content compared to its untreated counterpart. Liquid chromatography-mass
spectrometry (LC-MS) was used for characterization of chl a of the thylakoid membrane. UV-B exposure resulted in alterations
in the pigment-protein complexes 47 kDa and 43 kDa. Furthermore, 94 kDa and 20 kDa protein appeared in UV-B-exposed thylakoid
membrane of S. platensis. The composition of fatty acid in response to UV-B radiation was detected by gas chromatography–mass spectrometry having
23.5% saturated fatty acid (SFA), 76.4% monounsaturated fatty acid (MUFA), and polyunsaturated fatty acid (PUFA). In contrast
to its UV-B-untreated counterpart, SFA was 46.6%, and MUFA and PUFA were 53.3%. Our findings suggest that UV-B radiation not
only affects membrane morphology and its protein profile but also reduces saturated fatty acid and increases unsaturated fatty
acids in S. platensis. 相似文献
18.
Highly metastatic ras/myc-transformed serum-free mouse embryo (r/m HM-SFME-1) cells were injected subcutaneously to mice and the effects of Nω-nitro-l-arginine methyl ester (l-NAME) on the tumor progression and pulmonary metastasis were investigated. In addition, production of nitric oxide (NO), matrix
metalloproteinases (MMPs) and tumor necrosis factor-alpha (TNF-α) in the tumor cells and in a mouse macrophage-like cell line,
J774.1 cells, was analyzed. The increase in footpad thickness was significantly smaller in the mice which were fed the l-NAME containing water (4.24 ± 0.39 mg/day/mouse). The number of the tumor cells metastasized to the lungs was smaller in
the l-NAME treated mice, although statistical significance was not found. Co-treatment of r/m HM-SFME-1 cells with interferon-gamma (IFN-γ; 100 U/ml) and lipopolysaccharide (LPS; 0.5 μg/ml) significantly enhanced NO
production, and the presence of l-NAME at 1 mM significantly decreased this response. In r/m HM-SFME-1 cells, MMP-2 was undetectable and MMP-9 was also very little in the basal level, and both MMPs were unaffected
by the IFN-γ and/or LPS treatments, not to mention by the l-NAME treatment. In J774.1 cells, any treatment including LPS appeared to enhance MMP-9 production, however, this upregulation
was not inhibited by the additional presence of l-NAME. Production of TNF-α by J774.1 cells was markedly enhanced with LPS treatment, and this enhancement was significantly
reduced in the presence of l-NAME. These results indicate that the inhibitory effects of l-NAME on the tumor cell progression and pulmonary metastasis could be due to suppression of NO from tumor cells and TNF-α
from macrophages (Mol Cell Biochem, 2007).
Hideaki Yamaguchi and Yumi Kidachi contributed equally to this work. 相似文献
19.
Mahapatra Nitish R. Ghosh Sajalendu Sarkar Partha K. Banerjee Pataki C. 《Current microbiology》2003,46(5):0318-0323
When the highly metal-resistant acidophilic heterotrophic strain, Acidiphilium symbioticum KM2, was incubated with two Escherichia coli strains, viz. S17-1 (pSUP106) and K12, on a medium that supported growth of these two divergent species of different habitats,
E. coli transconjugants were isolated that contained novel plasmids and were resistant to Zn2+ (48 mM), Cu2+ (12 mM), Ni2+ (12 mM), chloramphenicol (50 μg/ml), and tetracycline (25 μg/ml). The transconjugant plasmids did not hybridize with any of the
A. symbioticum KM2 plasmids. After curing of the plasmids, the transconjugants became sensitive to 12 mM Zn2+, 12 mM Cu2+, and 12 mM Ni2+, but remained chloramphenicol and tetracycline resistant—the phenotypic markers that were originally present in pSUP106.
That a part of pSUP106 was integrated into the chromosome of the transconjugants was evident from the hybridization of pSUP106
with chromosomal DNA of the cured derivatives of the transconjugants. Further, the transconjugant plasmids hybridized only
with the chromosomal DNA of E. coli S17-1 and not with the chromosomal DNA of A. symbioticum KM2 or E. coli K12, suggesting their host chromosomal origin. Thus, the present study describes a unique event of genetic rearrangements
in the E. coli strain S17-1 (pSUP106), resulting in the formation of novel plasmids conferring metal-resistance phenotypes in the cell.
Received: 5 April 2002 / Accepted: 5 July 2002 相似文献
20.
孟庆焕;祖元刚;郭晓瑞;段喜华 《植物研究》2013,33(2):181-185
在增强UV-B辐射下,以3年生兴安落叶松幼苗为实验材料,研究了外源NO供体硝普钠(Sodium nitroprusside,SNP)对幼苗的光合色素(Chla、Chlb和Car)和叶绿素荧光参数的影响。方差分析结果表明0.5 mmol·L-1的SNP对增补UV B胁迫下的兴安落叶松幼苗产生显著影响。0.5 mmol·L-1的SNP能够显著抑制增补UV-B辐射后光合色素、Fv/Fm、ΦPSⅡ、Fv′/Fm′和qP的明显下降以及Chla /Chlb、Fo和NPQ的升高。表明了外源NO能够减轻UV-B辐射胁迫下兴安落叶松幼苗光合反应中心的生理损伤,从而增强兴安落叶松幼苗对增补UV-B辐射胁迫环境的适应能力。 相似文献