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1.
Summary Previous studies from our laboratory have shown that Cd 2+ can selectively disrupt E-cadherin-dependent cell-cell junctions in the porcine renal epithelial cell line, LLC-PK 1. The objective of the present studies was to determine whether or not Cd 2+ could produce similar effects in Madin-Darby canine kidney (MDCK) cells, an immortal epithelial cell line derived from dog
kidney. This is an important issue because MDCK cells have been used extensively as a model system to study the basic mechanisms
of E-cadherin-dependent cell-cell adhesion. MDCK cells on permeable membrane supports were exposed to Cd 2+ by adding CdCl 2 to either the apical or the basolateral compartment. The integrity of cell-cell junctions was assessed by morphologic observation
of the cells and by monitoring the transepithelial electrical resistance. The results showed that exposure to 10–40 μ M Cd 2+ for 15 min-4 h caused the cells to separate from each other without detaching from the growing surface. The separation of
the cells was accompanied by a marked drop in the transepithelial electrical resistance, a loss of E-cadherin from the cell-cell
contacts, and a reorganization of the actin cytoskeleton. These effects were much more pronounced when Cd 2+ was added basolaterally than when it was added apically. Moreover, the effects of Cd 2+ were qualitatively similar to those observed when the cells were incubated in Ca 2+-free medium. These results show that Cd 2+ can disrupt E-cadherin-dependent cell-cell junctions in MDCK cells, and they indicate that this cell line would be an appropriate
model for further mechanistic studies in this area. 相似文献
2.
The sensitivity of Saccharomyces cerevisiae to the redox-active metal copper has recently been found to be influenced by cellular fatty acid composition. This study
sought to investigate whether fatty acid composition affected plasma membrane permeabilisation and whole-cell toxicity induced
by the redox-inactive metal cadmium. S. cerevisiae NCYC 1383 was enriched with the polyunsaturated fatty acids linoleate (18:2) and linolenate (18:3) by growth in 18:2- or
18:3-supplemented medium. Incorporation of the exogenous fatty acids resulted in them comprising more than 65% of the total
fatty acids in plasma membrane lipids. Inhibition of cell division in the presence of Cd(NO 3) 2 was accentuated by growth in the presence of a polyunsaturated fatty acid. Furthermore, susceptibility to Cd 2+-induced plasma membrane permeabilisation increased with the degree of fatty acid unsaturation. Thus, during exposure to Cd 2+, K + efflux from 18:2- and 18:3-enriched cells was up to 2.5-fold or 3-fold greater, respectively than that from unsupplemented
cells. In addition, reductions in cell viability during exposure to Cd 2+ were most marked in polyunsaturated-fatty-acid-supplemented cells. At certain times, unsupplemented Cd 2+-exposed cells displayed up to 7-fold greater viability than supplemented Cd 2+-exposed cells. The study demonstrates that the toxicity of the redox-inactive metal Cd 2+ towards S. cerevisiae becomes markedly amplified with increased cellular and plasma membrane fatty acid unsaturation.
Received: 14 March 1997 / Received revision: 4 June 1997 / Accepted: 7 June 1997 相似文献
3.
The effect of different concentrations of cadmium on the viability, cell division, and the total increase in the biomass of
the VBI-O cell strain of tobacco (Nicotiana tabacumL., Virginia Bright Italia) was followed.
The concentration of 10 -6 mol 1 -1 Cd 2+ was fully tolerated by this strain, a nearly total inhibition of cell division and high cell mortality rate ocsicurred at
the concentration of 10 -4 mol1{si-1} Cd 2+.
Following a long-term exposure of the culture to gradually increasing cadmium concentrations, seven cell lines able to grow
on media containing 10 -4 mol 1 -1 Cd 2+ were derived. Phenotype diversity of the isolated cell lines likely causes of the disappearance of the resistance character
are discussed. 相似文献
4.
Recent studies have shown that Cd 2+ can damage the Ca 2+-dependent junctions between renal epithelial cells in culture, and preliminary evidence suggests that this effect may involve the interaction of Cd 2+ with E-cadherin, a Ca 2+-dependent cell adhesion molecule that is localized at the adhering junctions of epithelial cells. To determine whether or not Cd 2+ might bind directly to the E-cadherin molecule, we studied the binding of Cd 2+ to E-CAD1, a recombinant, 145-residue polypeptide that corresponds to one of the extracellular Ca 2+-binding regions of mouse E-cadherin. By using an equilibrium microdialysis technique, we were able to show that Cd 2+ could, in fact, bind to E-CAD1. The binding was saturable, with a maximum of one Cd 2+ binding site per E-CAD1 molecule. The apparent dissociation constant (K D) for the binding was about 20 μM, a concentration similar to that which has been shown to disrupt the junctions between epithelial cells. Other results showed that the binding of Cd 2+ was greatly reduced when excess Ca 2+ was included in the dialysis solution. These results suggest that Cd 2+ can interact with the Ca 2+ binding regions on the E-CAD1 molecule, and they provide additional support for the hypothesis that E-cadherin might be a molecular target for Cd 2+ toxicity. 相似文献
5.
This work explores the influence of cadmium on a suspension cell culture of Nicotiana tabacum (TBY‐2) by examining cell morphology, viability and DNA integrity. Changes in these parameters were strikingly dependent on concentration of cadmium in the culture medium: a concentration of 50–100 mmol m ? 3 CdSO 4 induced apoptotic changes including DNA fragmentation into oligonucleosomal units, while 1 mol m ? 3 Cd 2 + showed strong cytotoxicity, but no fragmentation of DNA. Low cadmium concentrations (below 10 mmol m ? 3) affected neither cell viability nor DNA integrity. A detailed kinetic study showed a significant delay in the onset of apoptosis after the application of high concentrations of cadmium. From days 0–3 after the application of 50 mmol m ? 3 CdSO 4, the morphology of the cells, their viability and growth were indistinguishable between control and treated cells, and ‘domain’ DNA fragmentation into 50–200 kb fragments was observed at the DNA level. After this (days 4–7), there was a characteristic and rapid decrease in cell viability, distinct changes in cell morphology and oligonucleosomal fragmentation. The results suggest that chronic exposure of plant cells to cadmium can trigger programmed cell death. 相似文献
6.
Previous work in our laboratory led to the isolation of a cadmium (Cd)-resistant variant (Cd r2C10) of the line CHO Chinese Hamster cell having a 10-fold greater resistance to the cytotoxic action of Cd 2+ compared with the CHO cell. This resistance was attributed to an increased capacity of the Cd 2+-resistant Cd r2C10 subline to induce synthesis of the Cd 2+- and Zn 2+-binding protein(s), metallothionein(s) (MT). Evidence that Cd 2+ behaves as an analog of the essential trace metal, Zn 2+, especially as an inducer of MT synthesis, suggested that the Cd r and CHO cell types could be employed to investigate cellular Zn 2+ metabolism. In the present study, measurements were made to compare CHO and Cd r cell types for (a) growth as a function of the level of ZnCl 2 added to the culture medium, (b) uptake and subcellular distribution of Zn 2+, and (c) capacity to induce MT synthesis. The results of these measurements indicated that (a) both CHO and Cd r cell types grew normally ( T
d≊16–18 h) during exposures to Zn 2+ at levels up to 100 μ M added to the growth medium, but displayed abrupt growth inhibition at higher Zn 2+ levels, (b) Cd r cells incorporate fourfold more Zn 2+ during a 24-h exposure to the maximal subtoxic level of Zn 2+ and (c) the CHO cell lacks the capacity to induce MT synethesis while the Cd r cell is proficient in this response during exposure to the maximal subtoxic Zn 2+ level. These findings suggest that (a) the CHO and Cd r cell systems will be useful in further studies of cellular Zn 2+ metabolism, especially in comparisons of Zn 2+ metabolism in the presence and absence of induction of the Zn 2+-sequestering MT and (b) a relationship exists between cellular capacity to induce MT synthesis and capacity for cellular
Zn 2+ uptake. 相似文献
7.
A marine bacterial strain putatively identified as Bacillus
thuringiensis strain DM55, showed multiple heavy metal resistance and biosorption phenotypes. Electron microscopic studies revealed that DM55 cells are encased in anionic cell wall polymers that can immobilize discrete aggregates of cations. Factors affecting cell surface affinity for metal cations, monitored by means of Cd 2+ binding capability, are investigated. The mechanisms of cadmium resistance and Cd 2+ biosorption by the bacterium appeared to be inducible and coincident. Medium components affecting metal removal under cadmium-stressed growth conditions were explored based on the application of two sequential multi-factorial statistical designs. Concentrations of potassium phosphates and peptone were the most significant variables. Optimized culture conditions allowed DM55 cells grown in the presence of 0.25 mM CdCl 2 to remove about 79% of the metal ions within 24 h with a specific biosorption capacity of 21.57 mg g –1 of biomass. Both fresh and dry cells of DM55 prepared under cadmium-free optimal nutrient condition were also able to biosorb Cd 2+. In addition to the concentration of phosphate in the medium, KinA, a major phosphate provider in the phosphorelay of Bacillus cells, was also demonstrated to regulate the magnitude of cell surface affinity for cadmium ions. 相似文献
8.
The expression of metallothionein (MT) and heat shock protein gene families was investigated in normal and in HeLa-derived cadmium-resistant cells, named H454. In the absence of amplification of MT genes H454 cells accumulated elevated concentrations of cadmium ions and synthesized higher levels of MT proteins than unselected HeLa cells. Northern blot analyses revealed higher levels of MT mRNAs in the resistant cells than in wild-type cells after Cd 2+and Zn 2+exposure. Evaluation of the cytotoxic potential of the different metals confirmed the high resistance to cadmium of the H454 cells. Two proteins of the heat shock family, hsp70 and GRP78, were synthesized in Cd 2+-exposed H454 cells at levels comparable to the ones present in Cd 2+-treated normal cells. Northern blot analyses of the mRNA levels corresponding to these proteins revealed elevated expression of both hsp70 and GRP78 mRNAs in H454 cells upon exposure to cadmium ions and no response to zinc induction. These data suggest the existence in the H454 cells of a cadmium-specific pathway of regulation of MT and heat shock genes. 相似文献
9.
The toxic effects of cadmium on growth and development of living organisms are well documented. However, the molecular mechanisms responsible for the inhibition of plant growth by cadmium are still not completely understood. We determined the effects of cadmium concentrations in the range of 1–11 μM on the growth of Glycine max L. cv. Navico suspension-culture cells, as well as on the expression of two cell cycle genes: cyclin B1 and cyclin-dependent type A kinase (CDK-A). There was no detectable decrease in cell viability at any tested Cd 2+ concentrations. The lower concentrations of Cd 2+ (1–4 μM) stimulated cell culture growth; however, this did not correspond with increased expression of cell cycle genes. The inhibition of cell growth was observed at concentration of Cd 2+ higher than 6 μM. Interestingly, it correlated well with the decreased cyclin B1 mRNA levels, but had no significant effect on the levels of CDK-A mRNA. 相似文献
10.
To identify some of the mechanisms involved in the high resistance to Cd 2+ in the protist Euglena gracilis, we studied the effect of Cd 2+ exposure on its energy and oxidative stress metabolism as well as on essential heavy metals homeostasis. In E. gracilis heterotrophic cells, as in other organisms, CdCl 2 (50 μM) induced diminution in cell growth, severe oxidative stress accompanied by increased antioxidant enzyme activity and
strong perturbation of the heavy metal homeostasis. However, Cd 2+ exposure did not substantially modify the cellular respiratory rate or ATP intracellular level, although the activities of
respiratory complexes III and IV were strongly decreased. In contrast, an enhanced capacity of the alternative oxidase (AOX)
in both intact cells and isolated mitochondria was determined under Cd 2+ stress; in fact, AOX activity accounted for 69-91% of total respiration. Western blotting also revealed an increased AOX
content in mitochondria from Cd 2+-exposed cells. Moreover, AOX was more resistant to Cd 2+ inhibition than cytochrome c oxidase in mitochondria from control and Cd 2+-exposed cells. Therefore, an enhanced AOX seems to be a relevant component of the resistance mechanism developed by E. gracilis against Cd 2+-stress, in addition to the usual increased antioxidant enzyme activity, that enabled cells to maintain a relatively unaltered
the energy status. 相似文献
11.
The aim of this study was to screen a strain for the removal of Cd 2+ from aqueous solution and investigate the characterization and mechanism of the Cd 2+ binding process. A novel strain of yeast showed high tolerance of cadmium, namely Cystobasidium oligophagum QN-3, was isolated from soils, which could resist 22,000 mg/L and 18,000 mg/L Cd 2+ on PDA (potato dextrose agar) plate and in PDA liquid medium, respectively. Cd 2+ binding experiment showed that the strain could remove Cd 2+ from aqueous solution effectively, the maximum Cd 2+ removal rate of 84.45% was achieved at initial Cd 2+ concentration 30 mg/L. Scanning electron microscopy (SEM) analysis revealed that sorption of Cd 2+ by cells could be associated with changes in the cell surface morphology. Fourier transform-infrared spectroscopy (FTIR) analysis confirmed the important role of the functional groups OH, CO, NH 2, COO , PO, and CH on the cell surface in the binding of Cd 2+. The comparison of the binding ability of different cellular parts indicated a significant role of the cell wall played in the Cd 2+ binding process. Pretreatment of the cells by boiling or ultrasonication could improve the biosorption capacity of QN-3. In addition, QN-3 exhibited selective and preferential property of binding capacity for other heavy metals, such as Pb 2+, Cu 2+, Cd 2+, Zn 2+, and Ni 2+. These data suggested the promising use of Cystobasidium oligophagum QN-3 as an effective and friendly biosorbent for cadmium or other heavy metals decontamination in the environment. 相似文献
12.
By observing increases in the transepithelial paracellular permeability of a range of radiolabeled solutes and electron dense dyes, changes in molecular sieving caused by the cytokine, TNF (tumor necrosis factor), and the phorbol ester, TPA (12-0-tetra-decanoylphorbol-13-acetate), were characterized. Using 14C-labeled mannitol (mw 182), raffinose (mw 504), PEG (polyethylene glycol; mw 4000), and dextran (mw 10,000, 70,000 and 2,000,000), the transepithelial flux rates of these compounds were determined at the peak of the transepithelial electrical resistance (TER) changes caused by these two agents. TNF treatment resulted in increased permeability across LLC-PK 1 epithelial cell sheets only to relatively small solutes, with an upper limit of approximately 4,000 mw. The low molecular weight “ceiling” for the TNF-treated epithelium is further evidence against TNF increasing transepithelial permeability by means of inducing nonspecific, microscopic “holes” in the epithelium, for which a “ceiling” would not exist. TPA treatment increases transepithelial paracellular permeability to a much broader range of solutes, extending well beyond 2 million mw. Transmission electron micrographs provide evidence that even the electron-dense dye complex, ruthenium red, can cross tight junctions of TPA-treated cell sheets. However, cationic ferritin cannot cross tight junctions of TPA-treated cell sheets. This shows that there is an upper limit to solutes able to cross TPA-treated cell sheets, but that this upper limit will include most proteins, which would then be able to cross tumor promoter-exposed (protein kinase C-activated) epithelial layers at accelerated rates. The biomedical implications for a high molecular weight cutoff in tumor promoter action in epithelial carcinogenesis, and for a low molecular weight cutoff in cytokine-induced epithelial apoptosis in inflammation, are discussed. J. Cell. Physiol. 171:226–233, 1997. © 1997 Wiley-Liss, Inc. 相似文献
13.
Summary The pig kidney cell line LLC-PK 1 cultured on a collagen coated membrane filter formed a continuous sheet of oriented asymmetrical epithelial cells joined by occluding junctions. A transepithelial electrical potential (PD) and short-circuit current (SCC) were dependent on the presence of Na and sugar in the apical bathing solution. In the presence of 5.5 mm d-glucose, a PD of 2.8 mV, apical surface negative, a SCC of 13 A cm –2 and transepithelial resistance of 211 ohm·cm 2 were recorded. The SCC was promptly reduced by the addition of phlorizin to the apical bath but unaffected when placed in the basolateral bath. The effect on SCC of various sugars was compared by the concentrations required for half-maximal SCC: 0.13 mm -methyl- d-glucoside, 0.28 mm d-glucose, 0.65 mm -methyl- d-glucoside, 0.77 mm 6-deoxy- d-glucose, 4.8 mm d-galactose, and 29 mm 3-O-methyl-glucose. When [Na] was reduced, the concentration of d-glucose required for half-maximal SCC increased. Isotopically labeled 3H and 14C d-glucose were used to simultaneously determine bidirectional fluxes; a resultant net apical-to-basolateral transport was present and abolished by phlorizin. The transported isotope cochromatographed with labeled d-glucose, indicating negligible metabolism of transported glucose. The pig kidney cell line, LLC-PK 1, provides a cell culture model for the investigation of mechanisms of transepithelial glucose transport. 相似文献
14.
Although cadmium-induced apoptosis of lymphocytes is one of common features in the immunotoxicity of cadmium, the membrane
pathway for intracellular cadmium accumulation is not fully elucidated. To characterize membrane Cd 2+ transport of rat thymocytes, the change in intracellular Cd 2+ concentration under various conditions was examined by the use of Fluo-3, a fluorescent probe for monitoring the change in
intracellular concentration of divalent metal cations. The membrane Cd 2+ transport was estimated by the augmentation of Fluo-3 fluorescence induced by bath application of CdCl 2. Lowering temperature strongly suppressed the augmentation of Fluo-3 fluorescence by CdCl 2, suggesting that the metabolic process can be involved in membrane Cd 2+ transport. External acidification (decreasing pH) and membrane depolarization by adding KCl attenuated the augmentation,
indicating the requirement of electrochemical driving force for membrane Cd 2+ transport into the cells. Bath application of CaCl 2 and ZnCl 2 equally decreased the augmentation, suggesting their competition with Cd 2+ at the membrane transport. The augmentation by CdCl 2 was lesser in the cells treated with N-ethylmaleimide inducing chemical depletion of cellular thiols. The result suggests
the contribution of sulfhydryl groups to membrane Cd 2+ transport. Taken together, it is suggested that the cells possess a temperature-sensitive membrane Cd 2+ pathway, driven by electrochemical gradient of Cd 2+ and transmembrane potential, with competitive binding site. Based on the characteristics described above, it is unlikely
that the membrane Cd 2+ transport in rat thymocytes is attributed to a single transport system although it has characteristics that are similar to
those of divalent cation transporter 1. 相似文献
15.
In order to probe the mechanism of survival at high concentrations of cadmium, a population of Cd 2+-resistant Chinese hamster ovary cells (CHO-K1M), was obtained by selective pressure. This stable population of cells were characterized as tolerant to 200 μM Cd 2+. In addition to the acquired resistance to Cd 2+, the CHO-K1M cells also demonstrated resistance to 2 mM Zn 2+. The CHO-K1M cells exhibit a diminished capacity to accumulate Cd 2+ at low concentration (0.5 or 1.0 μM), which is not evident at high Cd 2+ concentration. CHO-K1M cells demonstrated an induced synthesis of metallothionein as defined by physical characteristics and cysteine incorporation. The CHO-K1M cells cultured in the presence of 200 μM Cd 2+ were determined to have an intracellular concentration of metallothionein representing more than 50-fold that observed in the wild-type cells. These results suggest that in CHO-K1M cells, the induction of metallothionein synthesis represents the important parameter involved in the determination of resistance to high levels of Cd 2+ and Zn 2+. 相似文献
16.
Abscisic acid (ABA), a widely known phytohormone involved in the plant response to abiotic stress, plays a vital role in mitigating Cd2+ toxicity in herbaceous species. However, the role of ABA in ameliorating Cd2+ toxicity in woody species is largely unknown. In the present study, we investigated ABA restriction on Cd2+ uptake and the relevance to Cd2+ stress alleviation in Cd2+-hypersensitive Populus euphratica. ABA (5 μM) markedly improved cell viability and growth but reduced membrane permeability in CdCl2 (100 μM)-stressed P. euphratica cells. Moreover, ABA significantly increased the activity of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX), contributing to the scavenging of Cd2+-elicited H2O2 within P. euphratica cells during the period of CdCl2 exposure (100 μM, 24–72 h). ABA alleviation of Cd2+ toxicity was mainly the result of ABA restriction of Cd2+ uptake under Cd2+ stress. Steady-state and transient flux recordings showed that ABA inhibited Cd2+ entry into Cd2+-shocked (100 μM, 30 min) and short-term-stressed P. euphratica cells (100 μM, 24–72 h). Non-invasive micro-test technique data showed that H2O2 (3 mM) stimulated the Cd2+-elicited Cd2+ influx but that the plasma membrane (PM) Ca2+ channel inhibitor LaCl3 blocked it, suggesting that the Cd2+ influx was through PM Ca2+-permeable channels. These results suggested that ABA up-regulated antioxidant enzyme activity in Cd2+-stressed P. euphratica and that these enzymes scavenged the Cd2+-elicited H2O2 within cells. The entry of Cd2+ through the H2O2-mediated Ca2+-permeable channels was subsequently restricted; thus, Cd2+ buildup and toxicity were reduced in the Cd2+-hypersensitive species, P. euphratica. 相似文献
17.
As previously shown using phorbol ester tumor promoters (see Mullin and O'Brien: Am. J. Physiol., 251:C597–C602, 1986), diacylglycerols induce leakiness in LLC-PK 1 renal epithelial tight junctions. The similarity between phorbol ester and diacylglycerol action includes effects on (1) cell morphology, (2) dome formation, (3) transepithelial resistance and potential difference, (4) transepithelial flux of D-mannitol, and (5) mitogenesis. Four diacylglycerols have been tested: 1,2-dioctanoylglycerol; 1,2-dicaprylglycerol; 1,2-dioleoylglycerol; and 1-oleoyl-2-acetoyl-sn-3-glycerol. Their relative effectiveness depended upon the phenomenon being observed. Unlike phorbol esters, diacylglycerol effects were reversible within hours at 37°C in the continued presence of diacylglycerol, and effects were more pronounced when cell sheets were exposed to diacylglycerols from the basolateral cell surface. Overall, these findings indicate that previous results with phorbol esters may be attributed to the protein kinase C signal transduction system, and this system may therefore exert a role in transepithelial permeability. 相似文献
18.
Shoots of Jussiaea rapens Linn were exposed to nutrient solutions containing 0, 7, 15, 30, 60 mg L −1 cadmium (Cd 2+) and the effects on plant physiology investigated after treatment for 2 and 5 days. The net photosynthesis rate was inhibited by 54.8–62.7%, but only at the two highest [Cd 2+]. Stomatal conductance showed an initial decline from 0.01 to 0.07 mol m −2 s −1 after a 2-d exposure to high [Cd 2+] but recovered after a 5-d exposure. The Chl fluorescence parameters Fv/ Fm, qP and ETR also declined by 16, 87, and 90%, respectively, after 5-d at the highest [Cd 2+], which is consistent with damage to the activity of Photosystem II. Chlorophyll a (Chl a), and b and total chlorophyll (Chl) all exhibited content reductions, though in the case of Chl b it required a 5-d exposure. Significant increases in superoxide dismutase (SOD) activity were observed at all [Cd 2+], the greatest increase being 149%. Likewise, carotenoid content increased by five-fold relative to the untreated control values. The increase in SOD activity and carotenoid suggests that one effect of the Cd 2+ caused oxidative stress in J. rapens. Root vitality was also negatively influenced by all Cd 2+ treatments. However, the [Cd 2+] values inhibiting the photosynthetic parameters were greater than those reported for several other species, which suggests that J. rapens may have some degree of tolerance to this toxic metal. 相似文献
19.
The toxic metal ion cadmium (Cd 2+) induces pleiotropic effects on cell death and survival, in part through effects on cell signaling mechanisms and cytoskeletal dynamics. Linking these phenomena appears to be calmodulin‐dependent activation of the Ca 2+/calmodulin‐dependent protein kinase II (CaMK‐II). Here we show that interference with the dynamics of the filamentous actin cytoskeleton, either by stabilization or destabilization, results in disruption of focal adhesions at the ends of organized actin structures, and in particular the loss of vinculin and focal adhesion kinase (FAK) from the contacts is a result. Low‐level exposure of renal mesangial cells to CdCl 2 disrupts the actin cytoskeleton and recapitulates the effects of manipulation of cytoskeletal dynamics with biological agents. Specifically, Cd 2+ treatment causes loss of vinculin and FAK from focal contacts, concomitant with cytoskeletal disruption, and preservation of cytoskeletal integrity with either a calmodulin antagonist or a CaMK‐II inhibitor abrogates these effects of Cd 2+. Notably, inhibition of CaMK‐II decreases the migration of FAK‐phosphoTyr925 to a membrane‐associated compartment where it is otherwise sequestered from focal adhesions in a Cd 2+‐dependent manner. These results add further insight into the mechanism of the CaMK‐II‐dependent effects of Cd 2+ on cellular function. J. Cell. Biochem. 114: 1832–1842, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
20.
The effects of cadmium on the growth and respiration of two strains of Bacillus subtilis are compared to the accumulation of Cd by viable and cyanide-killed cells, protoplasts and cell fractions of the strains. Growth and respiration of strain 1A1 were significantly inhibited at 10g Cd 2+/ml while the growth and respiration of strain 1A1R, a selected mutant of 1A1, were only slightly affected. Similarly, 1A1R protoplasts were more resistant to Cd than were 1A1 protoplasts. The differential resistance of the strains correlates with the accumulation of Cd by the two strains, with 1A1 accumulating approximately 10 times the level of Cd after a 4 h exposure to 1 g Cd 2+/ml. The distributions of Cd throughout the cells, however, were similar between strains. Based on the accumulation of Cd by cyanide-killed protoplasts, uptake of Cd by 1A1 appears to be an active process, while for 1A1R, Cd accumulation is independent of protoplast viability.Non-standard abbreviations SMM
Subtilis Minimal Medium
- AAS
Atomic Absorption Spectrophotometry
- TSA
Trypticase Soy Agar
- PCA
Plate Count Agar
- INT
2-p-iodophenyl-3-p-nitrophenyl-5-phenyl-2H tetrazolium chloride
- dd H 2O
double distilled demineralized water
- OD
Optical Density 相似文献
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