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1.
Because the H2O2 and O2
− generated during a pathogen-triggered oxidative burst could either protect or destroy a besieged plant cell, their synthesis
might be expected to be tightly regulated. We have examined the nature of this regulation as it is communicated between homologous
and heterologous oxidative-burst pathways, using both chemical (oligogalacturonic acid, harpin, fensulfothion) and mechanical
(osmotic stress) stimuli to induce the burst. We report here that the above three chemical elicitors attenuate a subsequent
oxidative burst induced in cultured soybean (Glycine max L.) cells by either the same (homologous desensitization) or a different chemical elicitor (heterologous desensitization).
Further, when the magnitude of the initial oxidative burst is maximal, the cells remain refractory to subsequent elicitation
for at least 10 min and then revive their sensitivities to re-stimulation with a half-time of >20 min. Mechanical stimulation
of the oxidative burst appears to be regulated by a different set of constraints. Although initiation of a mechanically induced
burst leads to attenuation of a subsequent mechanically induced burst, the same mechanical stimulus is peculiarly unable to
reduce a subsequent chemically induced burst. The converse is also true, suggesting that heterologous desensitization of the
oxidative burst does not extend to mixed chemical and mechanical/osmotic stimuli. However, communication between these disparate
forms of elicitation is still demonstrated to occur, since low-level chemical stimuli strongly synergize concurrent low-level
osmotic stimuli and vice versa. Furthermore, the pattern of synergy changes dramatically if one stimulus is administered immediately
prior to the other. Taken together, these data demonstrate that significant cross-talk occurs among the different signaling
pathways of the oxidative burst and that the overall process is tightly regulated.
Received: 10 January 2000 / Accepted: 22 February 2000 相似文献
2.
The elicitor-induced oxidative burst in cultured chickpea cells drives the rapid insolubilization of two cell wall structural proteins 总被引:2,自引:0,他引:2
Elicitation of cultured chickpea cells caused rapid insolubilization of two cell wall structural proteins, p190, a putative hydroxyproline-rich glycoprotein and p80, a putative proline-rich protein. This process appeared to result from an H2O2-mediated oxidative cross-linking mechanism and was initiated within 5 min and complete within 20 min. Further, elicitation of cells induced a rapid, transient generation of H2O2 (oxidative burst), with an onset after 5 min and a maximum H2O2-release after 20 min, as measured by a luminol-dependent chemiluminescence assay. Both chemiluminescence and protein insolubilization were suppressed by exogenous application of catalase or diphenylene iodonium, an inhibitor of plasma-membrane NADPH oxidase, respectively. In contrast, exogenous H2O2 mimicked the effect of the elicitor, suggesting that the putative oxidative crosslinking of the proteins depends directly on H2O2 from the oxidative burst. The peroxidase inhibitor salicylhydroxamic acid blocked both the elicitor- and the exogenous-H2O2-stimulated insolubilization, indicating that a peroxidase activity downstream of H2O2-supply is required. The protein kinase inhibitor staurosporine blocked the elicitation of the oxidative burst and protein insolubilization. In contrast, the protein phosphatase 2A inhibitor cantharidin accelerated, potentiated and extended the elicited oxidative burst. Cantharidin even stimulated the responses in the absence of the elicitor. The competitive effect of both inhibitors confirms that a coordinated activation of (i) protein kinase(s) and (ii) counteracting protein phosphates(s) is a poised signal transduction step for the induction of an NADPH-oxidase-dependent oxidative burst, which drives the putative peroxidase-catalyzed cross-linking of the cell wall proteins.Abbreviations DPI
diphenylene iodonium
- Ext-1
extensin-1
- gE1
anti-glycosylated extensin-1 antibodies
- HRGP
hydroxyp-roline-rich glycoprotein
- LDC
luminol-dependent chemiluminescence
- POD
peroxidase
- PA
polyacrylamide
- PRP
proline-rich proteins
- SHAM
salicylhydroxamic acid
Financial support by Deutsche Forschungsgemeinschaft and Fonds der Chemischen Industrie is gratefully acknowledged. We thank Dr. C.J. Lamb (Salk Institute, La Jolla, Calif., USA) and Dr. L.A. Staehelin (University of Colorado, Boulder, Colo., USA) for their kind gifts of antibodies. 相似文献
3.
Plants have the ability to respond to pathogen invasion by specific defense reactions. Components of mammalian signal transduction
chains have been identified in plants, and several lines of evidence have implicated such components in elicitor signal transmission
in defense responses. In particular, it has been assumed that elicitor signals are transduced via a protein kinase cascade,
although the identity of the protein kinases and the function of the phosphorylated proteins remain to be determined. The
purpose of this review is to discuss the roles of protein kinases in elicitor signal transduction pathways in plant cells
based on recent progress in this field. 相似文献
4.
Sanguinarine is a potent inhibitor of oxidative burst in DMSO-differentiated HL-60 cells by a non-redox mechanism 总被引:1,自引:0,他引:1
Sanguinarine (SA), a member of the benzo[c]phenanthridine isoquinoline alkaloids, has been shown to possess antimicrobial, anti-inflammatory, and antioxidant properties. We examined the effects of SA on oxidative burst in DMSO-differentiated HL-60 cells, an excellent model for studying oxidative burst. SA inhibited both N-formyl-Met-Leu-Phe (fMLP) and phorbol 12-myristate 13-acetate (PMA)-induced oxidative burst with half-maximal concentration for inhibition (IC(50)) of 1.5 and 1.8 microM, respectively. Despite suggestions of SA antioxidant activity this inhibition cannot be ascribed to radical scavenging property of SA because the IC(50) for superoxide dismutase-like activity in a non-cellular system was 60 microM. TROLOX, a water-soluble vitamin E analog, had IC(50) of 3 microM in the same system. Moreover, cyclic voltammetry measurements show that SA is not an easily oxidizable species, with a peak anodic potential at 700 mV, as compared to TROLOX with peak anodic potential at 200 mV. On the other hand, TROLOX, when used in cell suspension, was much poorer inhibitor of oxidative burst than SA. When testing direct effect of SA on NADPH oxidase in the post-granular fraction of disrupted cells, the IC(50) was found to be 8.3 microM. It is higher than that observed in whole cells, however, the shift may be ascribed to SDS effect on SA activity. We conclude the SA inhibition of oxidative burst is not caused by SA redox activity but most likely is a result of SA affecting the activity of NADPH oxidase directly and in part by preventing the formation of NADPH oxidase protein complex. 相似文献
5.
The bacterial and serum factors involved in the oxidative response triggered by Salmonella typhimurium in differentiated U937 cells were investigated. Complement activation was shown to be required, using sera deficient in complement factors. An original dot-blot technique was developed to study the activation of complement by either bacteria or purified lipopolysaccharide (LPS). Both O-specific and lipid A segments of LPS were found to play a role in the triggering of the oxidative response. Lipid A was responsible for bacterial C3-derived opsonization by inducing an antibody-independent activation of complement classical pathway, whereas O-specific polysaccharide chains (O-Ag) were involved in cellular activation. Inhibition experiments using anti-cell surface marker monoclonal antibodies showed the involvement of the α chain of CR3 (CD11b) in the oxidative response developed by differentiated U937 cells in response to S. typhimurium infection. Whether both iC3b and O-Ag interact with different domains of CR3 or whether the binding of O-Ag occurs via a not yet identified receptor remains to be determined. 相似文献
6.
Summary Plant cells respond to a variety of external signals with the production of reactive-oxygen species. The enzyme system generating these reactive-oxygen species is believed to be an NADPH oxidase located in the plasma membrane and sharing similarities with the NADPH oxidase from mammalian macrophages. Antibodies directed against individual subunits (p22
phox
, p47
phox
, p67
phox
) of the human NADPH oxidase cross-react with soybean proteins of a similar size and subcellular location. An extensive expression screening of a soybean cDNA-library with the anti-human NADPH oxidase antibodies gave a single class of cDNA-clones for each antibody. However, the sequence analysis of these clones clearly demonstrates that the different antibodies recognise proteins which are unrelated to the expected oxidase subunits. The anti-p22
phox
antibody recognised a microsomal protein with no significant homology to any known protein in the database. One anti-p47
phox
antibody cross-reacted with the UDP-glucose dehydrogenase and another antibody bound to the chaperon peptidyl prolyl-cis-trans isomerase, both soluble cytosolic proteins. The anti-p67
phox
antibody detected the soluble enzyme acetohydroxy acid reductoisomerase. Chromatography of soybean protein extracts on an ion-exchange column (MonoQ, FPLC) gave a perfect comigration of the enzyme activity with the antibody signal, thus confirming these unexpected results by independent biochemical experiments.Abbreviations AARI
acetohydroxy acid reductoisomerase
- DPI
diphenylene iodonium
- GST
glutathione-S-transferase
- phox NADPH
oxidase of phagocytes
- ROS
reactive-oxygen species 相似文献
7.
The inoculation of primary pepper leaves with an avirulent strain of Xanthomonas campestris pv. vesicatoria induced systemic acquired resistance (SAR) in the non-inoculated, secondary leaves. This SAR response was accompanied by the systemic expression of the defense-related genes, a systemic microoxidative burst generating H2O2, and the systemic induction of both ion-leakage and callose deposition in the non-inoculated, secondary leaves. Some defense-related genes including those encoding PR-1, chitinase, osmotin, peroxidase, PR10, thionin, and SAR8.2 were markedly induced in the systemic leaves. The conspicuous systemic accumulation of H2O2 and the strong increase in peroxidase activity in the pepper leaves was suggested to play a role in the cell death process in the systemic micro-hypersensitive responses (HR), leading to the induction of the SAR. Treatment of the primary leaves with diphenylene iodinium (DPI), an inhibitor of oxidative burst, substantially reduced the induction of some of the defense-related genes, and lowered the activation of the oxidative bursts in the systemic leaves distant from the site of the avirulent pathogen inoculation and subsequently SAR. Overall, these results suggest that the induction of some defense-related genes as well as a rapid increase in oxidative burst is essential for establishing SAR in pepper plants. 相似文献
8.
The biological activities of mycorradicin, the major component of the yellow pigment formed in maize and other grasses upon
colonization by arbuscular mycorrhizal fungi, and corticrocin from the ectomycorrhizal fungus Piloderma croceum were analysed in cell cultures of tobacco (Nicotiana tabacum L.) and alfalfa (Medicago sativa L.). Tobacco and alfalfa suspension cell cultures react to elicitor treatment by alkalinization of the culture medium and
generation of activated oxygen species, the so-called oxidative burst. In the present study, the addition of corticrocin suppressed
the elicitor-induced oxidative burst reaction but not the alkalinization. The suppression of the oxidative burst by corticrocin
was dose dependent. Mycorradicin in either its methylated or free form had no effect on the oxidative burst or the alkalinization.
Accepted: 20 March 2001 相似文献
9.
Skov KA 《Mutation research》1999,430(2):126-253
The rationale for and importance of research on effects after radiation at "low doses" are outlined. Such basic radiobiological studies on induction of repair enzymes, protective mechanisms, priming, and hypersensitivity are certainly all relevant to treatment of cancer (see Section 1, Studies at low doses - relevance to cancer treatment). Included are examples from many groups, using various endpoints to address the possibility of an induced resistance, which has been compared to the adaptive response [M.C. Joiner, P. Lambin, E.P. Malaise, T. Robson, J.E. Arrand, K.A. Skov, B. Marples, Hypersensitivity to very low single radiation doses: its relationship to the adaptive response and induced radioresistance, Mutat. Res. 358 (1996) 171-183.]. This is not intended to be an exhaustive review--rather a re-introduction of concepts such as priming and a short survey of molecular approaches to understanding induced resistance. New data on the response of HT29 cells after treatment (priming) with co-cultured activated neutrophils are included, with protection against X-rays (S1). Analysis of previously published results in various cells lines in terms of increased radioresistance (IRR)/intrinsic sensitivity are presented which complement a study on human tumour lines [P. Lambin, E.P. Malaise, M.C. Joiner, Might intrinsic radioresistance of human tumour cells be induced by radiation?, Int. Radiat. Biol. 69 (1996) 279-290].It is not feasible to extrapolate to low doses from studies at high doses. The biological responses probably vary with dose, LET, and have variable time frames. The above approaches may lead to new types of treatment, or additional means to assess radioresponsiveness of tumours. Studies in many areas of biology would benefit from considerations of different dose regions, as the biological responses vary with dose. There may also be some implications in the fields of radiation protection and carcinogenesis, and the extensions of concepts of hyper-radiosensitivity (HRS)/IRR extended to radiation exposure are considered in Section 2, Possible relevance of IRR concepts to radiation exposure (space). More knowledge on inducible responses could open new approaches for protection and means to assess genetic predisposition. Many endpoints are used currently--clonogenic survival, mutagenesis, chromosome aberrations and more direct--proteins/genes/functions/repair/signals, as well as different biological systems. Because of scant knowledge of the relevant aspects at low doses, such as inducible/protective mechanisms, threshold, priming, dose-rate effects, LET within one system, it is still too early to draw conclusions in the area of radiation exposure. Technological advances may permit much needed studies at low doses in the areas of both treatment and protection. 相似文献
10.
Gupta RR Yoo DJ Hebert C Niger C Stains JP 《Biochemical and biophysical research communications》2010,396(2):258-264
Cycloheximide (CHX) is one of the most interesting protein synthesis inhibitors. For this reason, fluorescent derivatives of CHX could find useful applications in cell biology. We report the successful synthesis of a set of novel fluorescent derivatives of CHX. The effect of different functional groups on the biological activity of CHX was studied upon their modification through suitable strategies, i.e., acetylation of the hydroxyl group and reductive amination of the ketone group. The first route induced a complete loss of biological activity, while the second approach allowed a retained inhibition of protein synthesis, as demonstrated by in vitro translation assays. Various fluorescent dyes for reductive amination were tested (i.e., ANTS, APTS, and Rhodamine-123), and the success of the syntheses was demonstrated by diverse analytical techniques. Cycloheximide labeling with fluorescent dyes is a promising approach for developing fluorescence reporters for various applications, both in vitro (fluorescence spectroscopy) and in vivo (live imaging). 相似文献
11.
Group B streptococci (GBS) are a major cause of meningitis and septicemia in neonates and numerous invasive diseases in adults. Host defense against GBS infections relies upon phagocytosis and killing by phagocytic cells. To better understand the importance of this defense mechanism a flow cytometric assay was developed to study phagocytosis and oxidative burst of leukocytes stimulated by bacteria. GBS labeled with fluorescein isothiocyanate were used for phagocytosis experiments and the extracellular fluorescence was quenched by ethidium bromide to differentiate intracellular from extracellular bacteria. The intracellular oxidative burst was determined by using 2',7'-dichlorofluorescein diacetate to measure hydrogen peroxide production and hydroethidine for superoxide anion production. We found that for GBS serotypes Ia, Ib/c, II, and III phagocytosis was greater in neutrophils than monocytes. Hydrogen peroxide production and superoxide anion production were also greater for neutrophils than monocytes in all serotypes tested. A comparison of seven type III strains revealed greater phagocytosis and superoxide anion production by neutrophils than monocytes but no difference in hydrogen peroxide production. Therefore, monocytes react similarly as neutrophils in response to GBS but at a reduced level. This methodology of measuring both phagocytosis of GBS and oxidative burst simultaneously in neutrophils and monocytes should be very useful in further studies on the importance of factors such as complement and IgG receptors for the killing of bacteria. 相似文献
12.
《Bioorganic & medicinal chemistry》2016,24(16):3556-3564
Colon cancer is one of the most incident cancers in the Western World. While both genetic and epigenetic factors may contribute to the development of colon cancer, it is known that chronic inflammation associated to excessive production of reactive oxygen and nitrogen species by phagocytes may ultimately initiate the multistep process of colon cancer development. Phenolic compounds, which reveal antioxidant and antiproliferative activities in colon cancer cells, can be a good approach to surpass this problem. In this work, hydroxycinnamic amides and the respective acid precursors were tested in vitro for their capacity to modulate human neutrophils’ oxidative burst and simultaneously to inhibit growth of colon cancer cells. A phenolic amide derivative, caffeic acid hexylamide (CAHA) (4) was found to be the most active compound in both assays, inhibiting human neutrophils’ oxidative burst, restraining the inflammatory process, inhibiting growth of colon cancer cells and triggering mitochondrial dysfunction that leads cancer cells to apoptosis. Altogether, these achievements can contribute to the understanding of the relationship between antioxidant and anticancer activities and based on the structure–activity relationships (SAR) established can be the starting point to find more effective phenolic compounds as anticancer agents. 相似文献
13.
Winters KR Meyer E Van Merris VM Van Den Broeck WL Duchateau L Burvenich C 《Steroids》2003,68(5):397-406
During the periparturient period, dairy cows are subjected to physiological changes that may induce immunosuppression and an increased susceptibility of the animal to bacterial infections such as mastitis. The incidence of clinical environmental mastitis is high during the last period of gestation, at parturition and during the first month of lactation, suggesting a potential influence of sex steroid hormones. Efficient functioning of polymorphonuclear leukocytes (PMN) is necessary during the early phase of infection to clear the mammary gland from invading pathogens. The purpose of this study was to investigate the effect of sex steroid hormones on the oxidative burst activity of isolated PMN from ovariectomized cows. Ovariectomy was performed to minimize the interference of endogenous estrogen and progesterone levels, which are known to vary extensively during the estrus cycle. Isolated PMN were incubated with different concentrations of 17beta-estradiol, estrone or progesterone. A flow cytometric technique was used to quantify the oxidation of intracellular 2',7'-dichlorofluorescin by the oxidative burst system of PMN following stimulation with phorbol myristate acetate. Staurosporine was used as a positive control for our in vitro model. No statistically significant changes in PMN oxidative burst activity were observed at physiological or pharmacological levels of the three sex steroid hormones. A large variation existed in the oxidative burst activity among cows. In an additional experiment, the expression of estrogen receptor alpha and of progesterone receptor in PMN was evaluated immunohistochemically. No specific staining was detected for both receptors in isolated PMN following incubation with different concentrations of sex steroid hormones. 相似文献
14.
Anna Źróbek-Sokolnik Han Asard Kamilla Górska-Koplińska Ryszard J. Górecki 《Acta Physiologiae Plantarum》2009,31(1):43-49
Generation of reactive oxygen species (ROS) constitutes an important first reaction under many stress conditions in plants.
We demonstrate that Nicotiana tabacum L. cv. Bright Yellow 2 (TBY-2) cells in suspension cultures, generate superoxide radical and hydrogen peroxide upon treatment
with cadmium and zinc. Addition of catalase and N,N-diethyldithiocarbamate (DDC) decreased the level of H2O2, whereas superoxide dismutase (SOD) induced a slight increase of the H2O2 production. The effects of catalase, DDC and SOD on the heavy metal-induced ROS production indicate that it occurs outside
of the cells, and that at least part of the hydrogen peroxide is produced by dismutation of the superoxide radical (O2
·−). The effect of pretreatment of the cell cultures with commonly used mammalian NADPH oxidase inhibitors was also tested.
Strong inhibitions of cadmium and zinc-mediated ROS production were obtained with the flavoprotein inhibitors—diphenylene
iodonium (DPI) and quinacrine and with an inhibitor of b-type cytochromes—imidazol. Membrane permeable-N-ethyl maleimide (NEM) and iodoacetate, and membrane non-permeable thiol reagents—para-chloromercuribenzoic acid (pCMBS) also
inhibited the ROS production. These results suggested that the enzyme responsible for cadmium and zinc-induced ROS production
in tobacco cells contains a flavocytochrome. They also show the importance of intra- and extracellular thiol groups in the
observed stress reaction. The induction of ROS production with heavy metals showed properties comparable to the elicitor-induced
oxidative burst in other plant cells. 相似文献
15.
Lee CK Park HJ So HH Kim HJ Lee KS Choi WS Lee HM Won KJ Yoon TJ Park TK Kim B 《Proteomics》2006,6(24):6455-6475
We used 2-DE and MALDI-TOF/TOF to identify proteins of vascular smooth muscle cells whose expression was or was not altered by exposure to 500 microM H2O2 for 30 min. We detected more than 800 proteins on silver-stained gels of whole protein extracts from rat aortic smooth muscle strips. Of these proteins, 135 clearly unaffected and 19 having levels altered by exposure to H2O2 were identified. Protein characterization revealed that the most prominent vascular smooth muscle proteins were those with antioxidant, cytoskeletal structure, or muscle contraction. In addition, cofilin, an isoform of the actin depolymerizing factor family, shifted to its basic site on the 2-DE gel as a result of H2O2 treatment. In Western blot analysis of proteins from A7r5 aortic smooth muscle cells, the phosphorylation, but not the expression, of cofilin was decreased by H2O2 in a dose-dependent manner. The H2O2-induced dephosphorylation of cofilin and apoptosis was inhibited by Na3VO4, an inhibitor of protein tyrosine phosphatase (PTP). These results suggest that cofilin is one of the proteins regulated by H2O2 treatment in vascular smooth muscle, and has an important role in the induction of vascular apoptosis through PTP-dependent mechanisms. 相似文献
16.
Four new caffeoyl -glucaric and -altraric acid derivatives along with eleven known compounds were isolated from aerial parts of Galinsonga parviflora. Their structures were elucidated by high-resolution spectroscopic studies. The four new compounds were determined as being 2,3,4,5-tetracaffeoylglucaric acid (1), 2,4,5-tricaffeoylglucaric acid (2), 2,3,4- or 3,4,5-tricaffeoylaltraric acid (3) and 2,3(4,5)-dicaffeoylaltraric acid (4). A reliable criterion for the determination of the linkage position of caffeic acids moieties in glucaric acid derivatives has been proposed, on the basis of detailed analysis of the respective J-couplings, including substitution and solvent influence on the observed values. All hexaric acids derivatives appeared as inhibitors of reactive oxygen species production by stimulated neutrophils. 相似文献
17.
The superoxide anion generation in Ehrlicg ascites tumour (EAT) cells increased more than two-fold in the presence of the tumour promoter, tetradecanoyl phorbol myristate acetate (TPA). Epinephrine and dibutryl cAMP (Bt2 cAMP) inhibited in a dose-dependent manner, both basal and TPA-triggered superoxide generation in EAT cells. The kinetics of inhibition of superoxide generation showed a maximum inhibition between 30 and 40 min of preincubation with epinephrine or Bt2 cAMP of EAT cells and coincided with an increase in activity of a phosphoprotein phosphatase. In TPA-treated EAT cells, epinephrine or Bt2 cAMP increased the phosphatase activity in a dose-dependent manner. In vitro EGTA, EDTA and sodium fluoride inhibited phosphatase activity. Superoxide generation in response to TPA in Triton-permeabilized EAT cells was inhibited by inclusion of the phosphatase in the assay. Taken together, these results clearly suggest that the phosphatase activity in EAT cells develops as a result of protein kinase A (PKA) and protein kinase C (PKC)-mediated phosphorylation of the phosphatase which then mediates dephosphorylation of the PKC-triggered phosphorylation of proteins to inhibit respiratory burst. A cross-talk between PKA and PKC pathways negatively modulates superoxide generation in EAT cells. 相似文献
18.
Potential role of NADPH-oxidase in early steps of lead-induced oxidative burst in Vicia faba roots 总被引:1,自引:0,他引:1
Pourrut B Perchet G Silvestre J Cecchi M Guiresse M Pinelli E 《Journal of plant physiology》2008,165(6):571-579
The mechanism of oxidative burst induced by lead in Vicia faba excised roots was investigated by luminol-dependent chemiluminescence. Results showed that lead triggered a rapid and dose-dependent increase in chemiluminescence production. In this study, specific inhibitors of putative reactive oxygen species (ROS) sources were used to determine the mechanism of lead-induced ROS generation. This generation was sensitive to dephenylene iodonium (DPI), quinacrine and imidazole, some inhibitors of the NADPH-oxidase and not inhibited by other putative ROS sources inhibitors. Data reported in this work clearly demonstrated the pivotal role of NADPH-oxidase-like enzyme in early steps of lead-induced oxidative burst. To investigate the respective implication of calmodulin and protein kinase (PK) in lead-induced NADPH-oxidase activation, excised roots were treated with the calmodulin inhibitor W7 or with the PK inhibitor staurosporine. The chemiluminescence generation inhibition by these inhibitors illustrated the role of PK in lead-induced NADPH-oxidase activation and revealed a calmodulin-dependent step. Using the calcium entry blocker La3+ or different concentrations of calcium in the extra-cellular medium, our data highlighted the implication of Ca2+ channel in lead-induced oxidative burst. 相似文献
19.
Even though the molecular mechanisms by which lead induces toxicity and cancer have been intensely studied for many years,
its carcinogenic mechanisms are not well understood yet. Several possible mechanisms have been examined to gain understanding
on the carcinogenic properties of lead, which include mitogenesis, alteration of gene expression, and oxidative damage, among
others. The aim of the present study was to explore the induction of oxidative damage at low lead concentrations using human
embryonic hepatic cells WRL-68. Our results showed induction of reactive oxygen species, changes in the superoxide dismutase
and catalase activity, as well as an induction of lipidperoxidation and DNA damage. However, after 5 weeks of exposure, these
alterations returned to their basal levels. These results taking together indicate that at low concentrations, lead is able
to establish an oxidative stress scenario; however under optimal antioxidant defense the oxidative scenario could be abolished
through an adaptative process. 相似文献