BDE-47对人胚肾细胞HEK293的毒理效应及作用机制

2,2’,4,4’-四溴联苯醚(BDE-47)是生物体中含量最高且毒性最强的PBDEs之一,有关BDE-47对肾细胞的毒性及其作用机制的研究仍有待补充。选取3个剂量组(低:10-6mol·L-1、中:10-5mol·L-1、高:10-4mol·L-1)及溶剂对照组,研究了BDE-47对人胚肾细胞(HEK293)的细胞凋亡率及活性氧(ROS)水平的影响;并从分子水平对细胞氧化损伤、凋亡相关蛋白(APE1及p53)及凋亡相关基因m RNA(p53、Bax、Caspase 3、Caspase 8)的表达量进行测定。实验结果显示:与对照组相比,中、高剂量组细胞凋亡率显著增加(P0.05);ROS水平在中剂量组显著上升(P0.01);随BDE-47浓度的变化,APE1蛋白表达量与细胞ROS水平存在一致性;p53、Bax、Caspase 8 m RNA表达量与BDE-47的浓度间存在剂量-效应关系。结果表明,BDE-47可诱导HEK293细胞凋亡及氧化应激,APE1可能是细胞ROS升高与细胞凋亡间重要的中介因子;BDE-47可以通过影响Caspase 8及线粒体途径中p53及Bax的表达诱导细胞凋亡。     

Epigenetic effect of long-term bisphenol A exposure on human breast adenocarcinoma cells

In this research, epigenetic effects of bisphenol A (BPA) on human breast cancer MCF-7 cells were analyzed. Genome-wide DNA methylation and gene expression were analyzed in MCF-7 cells exposed to BPA (10^?5 and 10^?6 mol/L for 5 weeks). No significant changes in the global level of 5-methyl-2′-deoxycytidine and 5-hydroxymethyl-2′-deoxycytidine were observed. DNA methylation profiling analysis indicated that BPA exposure resulted in the hypermethylation of FOXK2, LKB1, LMX1A and CUGBP2 and the hypomethylation of PTPRN2, TRIM27, BCAS3 and ZNF423. Decreased expression of apoptosis genes (P38 and BCL2L1) and increased expression of chemokine (Cxcl2 and ccl20) were detected. Changes of these genes were speculated to affect the ERα-related cell growth as well as cell apoptosis.     

Epigenetic effects of N-methyl-N′-nitro-N-nitrosoguanidine on Kazakh esophageal epithelial cells

Epigenetic change is a key factor for esophageal cancer progression. This study shows that upon exposure of primary cultures of human esophageal epithelial cells obtained from people of the Kazakh nationality in China to N-methyl-N′-nitro-N-nitrosoguanidine at concentrations of 0.75, 1.50, and 3.00 mg/L, (1) cell proliferation was inhibited, the percentages of cells in the G₀ and G₁ phases declined, and those in the S and G₂ + M phases increased at all concentrations, while apoptosis rates increased at medium and high concentrations; (2) the content of DNA-methyltransferases 3a and 3b and the activities of DNA-methyltransferase 1 and DNA-methyltransferase 3a increased at all concentrations while the content of DNA-methyltransferase 1 and the activity of DNA-methyltransferase 3b were increased only at the high concentration; (3) messenger RNA and protein levels of DNA-methyltransferases 1, 3a, and 3b were increased at all concentrations. Obviously, N-methyl-N′-nitro-N-nitrosoguanidine in the low mg/L range can inhibit the proliferation of normal Kazakh esophageal epithelial cells, can cause cell cycle arrest in the S and G₂ + M phases, promote apoptosis, and increase the activities of DNA-methyltransferases 1, 3a, and 3b.     

Cell cycle and toxin production in the benthic dinoflagellate Prorocentrum lima

Profiles of diarrhetic shellfish poisoning (DSP) toxins produced throughout the growth cycle and the cell cycle of the toxigenic marine dinoflagellate Prorocentrum lima were studied in triplicate unialgal batch cultures. Cells were pre-conditioned at 18 ± 1 °C, under a photon flux density (PFD) of 90 ± 5 μmol m⁻² s⁻¹ on a 14 h light:10 h dark photoperiod. In exponential growth phase, cultures were synchronized in darkness for 17 d. After dark synchronization, cultures were transferred back to the original photoperiod regime. Cells were harvested for DSP toxin analysis by LC-MS (liquid chromatography with mass spectrometry), and double-stranded (nuclear) DNA was quantified by flow cytometry. The cell populations became asynchronous within approximately 3 d after transition from darkness to the 14 h light:10 h dark photoperiod. This may be due to the prolonged division cycle (5 to 7 d) that is not tightly phased by the photoperiod. Unlike other planktonic Prorocentrum spp., cytokinesis in P. lima occurred early in the dark and ceased by “midnight”. Cellular levels of the four principal DSP toxins, okadaic acid (OA), OA C8-diol-ester (OA-D8), dinophysistoxin-1 (DTX1) and dinophysistoxin-4 (DTX4), ranged from 0.37 to 6.6, 0.02 to 1.5, 0.04 to 2.6, and 1.8 to 7.8 fmol cell⁻¹, respectively. No toxin production was evident during the extended period of dark synchronization nor during the initial period when NH₄ was consumed as the major nitrogen source. Soon after the cells were returned to the 14 h light:10 h dark cycle and they began to take up NO₃, cellular levels of all four toxins gradually increased. This increase in DSP toxins usually occurred in the light, marked by a rise in DTX4 levels that preceded an increase in the cellular concentration of OA and DTX1 (delayed by 3 to 6 h). Thus, DTX4 synthesis is initiated in the G1 phase of the cell cycle and persists into S phase (“morning” of the photoperiod), whereas OA and DTX1 production occurs later during S and G2 phases (“afternoon”). No toxin production was measured during cytokinesis, which happened early in the dark. The evidence indicates that toxin synthesis is restricted to the light period and is coupled to cell cycle events. Received: 3 September 1998 / Accepted: 30 March 1999     

Relationships between nucleic acid concentrations and primary production in the Catalan Sea (Northwestern Mediterranean)

We explored the relationships between classical estimators of autotrophic biomass and primary production, such as chlorophyll a concentration and ¹⁴C-fixation rates, and biochemical indices based on DNA and RNA determinations, which have been proposed as indicators of physiological state in natural plankton populations. The measurements were made during two cruises across the Catalan Front, carried out in May 1989 and February 1990, corresponding respectively, to periods of stratification and moderate mixing. DNA and RNA concentrations (measured by a double-staining fluorimetric technique) were significantly correlated with chlorophyll a in February 1990, but not in May 1989, when a marked deep chlorophyll maximum was present. Significant positive correlations between RNA concentration and primary production and between RNA: DNA and primary production were found during both surveys, probably reflecting both higher RNA concentrations per cell and enhanced bacterial and microheterotrophic growth in high primary production situations. The results support the potential usefulness, in biological oceanography, of biochemical indicators based on DNA and RNA concentrations.     

Fluoride induces DNA damage and cytotoxicity in human hepatocellular carcinoma cells

Humans are primarily exposed to fluoride (Fl), a widespread environmental pollutant, via contaminated drinking water and foodstuffs. The aim of this study was to examine whether sodium fluoride (NaF) exerted cytotoxic effects in human hepatocarcinoma (HepG2) cells. HepG2 cells were incubated with different concentrations of NaF and reactive oxygen species (ROS) levels, cell cycle, apoptosis, and DNA damage determined. Concentration-dependent studies showed that exposure to HepG2 cells with different concentrations of NaF for 24 hr significantly decreased cell viability and intracellular antioxidant capacity. Furthermore, NaF exposure increased lipid peroxidation levels and accumulation of intracellular ROS; and lowered antioxidant glutathione concentrations. In addition to oxidative impairments, NaF treatment enhanced HepG2 cell death via apoptotic pathway as evidenced by DNA fragmentation and cell cycle arrest. Sodium fluoride treatment unregulated p53 level, and Bax and Bcl2 expression. Diminished cell viability and changes in cell cycle accompanied a rise in p53 expression.     

Evaluation of hemopoietic responses in Labeo rohita Hamilton following acute copper toxicity

Fish are often exposed to highly contaminated water, especially in areas where the dilution rate of waste water is low. Environmental pollutants or other stress may affect one or more of the immunological functions in fish. Effective control of toxic substances is essential for the success of fish culture, which requires fish health monitoring using biomarkers. This study evaluated the effects of heavy metal copper (Cu) at environmentally relevant concentrations on the hematopoiesis in Labeo rohita. L. rohita fingerlings were exposed to different Cu concentrations for 6, 24, 48, or 72 hr. Following exposure, percentage blast cells was found to be increased after 6 and decreased after 24, 48, and 72 hr both at sublethal and LC₅₀ concentrations, whereas percentage mature erythrocytes decreased after 6 and increased after 24, 48, and 72 hr. Erythropoietic and leukopoietic efficiencies were also affected upon exposure. Erythropoietic and leucopoietic efficiencies increased markedly after 6, 24, and 48 hr but decreased after 72 hr in sublethal-treated fish. Erythropoietic efficiency decreased significantly after 6, 24 and 48 hr but increased after 72 hr in LC₅₀-treated fish. Leukopoietic efficiency decreased significantly after 6 hr exposure and increased after 24 and 48 hr but decreased after 72 hr. Flow cytometric studies of head kidney cell cycle phase distribution revealed cell death and DNA synthesis. The percentage cell death increased in fish exposed to sublethal concentrations and rose further at LC₅₀ during the earlier hours of exposure. Synthesis of DNA was increased at sublethal concentrations but was significantly reduced at LC₅₀ dose.     

Toxic effects of realgar transforming solution on the reproduction of Caenorhabditis elegans

Realgar transforming solution is an arsenic formulation which has shown anticancer effects with low toxicity both in vivo and in vitro. In this study, Caenorhabditis elegans was used to evaluate its reproductive toxicity and its possible mechanisms. Realgar transforming solution decreased the brood size and induced proliferation arrest and apoptosis significantly only at an elemental concentration of 37.5 mg/L, while arsenic trioxide reduced the brood sizes and induced proliferation arrest and apoptosis of both the wild type N2 and let-60 ras(gf) mutant worms in an arsenic concentration dependent manner. Mitogen-activated protein kinase and protein p53 pathways may be involved in reproductive toxicity as evidenced by real-time quantitative polymerase chain reaction, RNA interference, and inhibition experiments with mitogen-activated protein kinases and p53. In conclusion, realgar transforming solution at the low arsenic (As) concentrations showed lower reproductive toxicity than arsenic trioxide, and a different molecular mechanism of reproductive toxicity is suggested.     

重金属Cr(VI)、Pb及Cu胁迫对双齿围沙蚕体腔细胞的DNA损伤

为探讨重金属Cr(VI)、Pb以及Cu对沙蚕体腔细胞DNA的毒性效应,以双齿围沙蚕为受试动物,重金属按不同剂量水平,Cr(VI):10、100和200 mg·L~(-1),Pb:5、50和100 mg·L~(-1),Cu:1、10和20 mg·L~(-1),分别胁迫沙蚕24 h,以不加任何重金属离子的海水为对照,采用单细胞凝胶电泳技术,检测其体腔细胞DNA损伤程度。结果表明,与空白对照组相比,3种重金属离子的各浓度组都能引起沙蚕体腔细胞DNA损伤,且3种重金属胁迫浓度与细胞DNA损伤程度之间存在显著的剂量-效应关系。双齿围沙蚕可以作为单细胞凝胶电泳的实验材料用于重金属所致环境污染的生物监测指示生物。     

Polyploidy and polyteny in the gigantic eubacterium Epulopiscium fishelsoni

Content and distribution of basic proteins, histones, acidic proteins and DNA, as well as the interaction of basic proteins with DNA, were studied microfluorometrically within nucleoid bodies of the gigantic eubacterium Epulopiscium fishelsoni living in the guts of the algivorous surgeonfish Acanthurus nigrofuscus. The fine structure of the bacterial nucleoid was studied using transmission electron microscopy (TEM). The mean content of basic proteins, histones and acidic proteins per nucleoid was directly proportional both to cell volume and DNA amount, proving that these proteins are integral components of bacterial chromatin. The maximal DNA quantity of ~10 ¹² base pairs nucleoid ^-1 was found in the largest specimens of 354,000 µm ³ volume (150-fold more then in human lymphocyte). Binding of proteins to DNA was strongest in cup-like nucleoids at the end of the bacterial life cycle, and weakest in enlarged and elongated nucleoids in mid-cycle. Contact fluorescent microscopy and TEM revealed a non-homogenous distribution of these proteins within the nucleoids, as well as the presence of giant polytene chromosome(s). We assume that the unusual genetic and morphological peculiarities, particularly increased polyploidy and polyteny, as revealed in E. fishelsoni, are the results of specific adaptations to the chemical conditions in the host's gut.     

Phosphorus metabolism of oceanic dinoflagellates: phosphate uptake,chemical composition and growth of Pyrocystis noctiluca

The phosphorus metabolism of Pyrocystis noctiluca Murray (Schuett) 1886 has characteristics which may enhance its potential for success in orthophosphate impoverished waters. The steady-state phosphate uptake rates were equal in the light and dark, and were directly proportional to both the phosphorus cell quota and the cell division rate. In contrast, nutrient-saturated uptake rates were multiphasic, faster in the light than the dark, 2 to 4 orders of magnitude greater than steady-state rates, and were inversely proportional to both the phosphorus cell quota and the cell division rate. These uptake characteristics suggest that P. noctiluca may take up phosphate coincidently at their typically low ambient concentrations as well as to exploit episodic nutrient events in nature. Cell division rates were a hyperbolic function of the ambient orthophosphate concentration. The shortest doubling time was 8.7 d, the phosphate concentration at half the maximum division rate was 0.15 M and the threshold, concentration for cell division was ca 0.05 M PO ₄ ^3- . Division rates of P. noctiluca in the ocean are much faster than predicted from the measured ambient orthophosphate concentrations. Since this dinoflagellate has high naturally occurring alkaline phosphatase activities, and can utilize organic-P compounds, we suggest that organic-P can be as important as orthophosphate in supporting the observed division rates of P. noctiluca in the sea.     

Apoptosis in marine sponges: a biomarker for environmental stress (cadmium and bacteria)

The marine demosponge Suberites domuncula is abundantly present on muddy sand bottoms, both in the open sea and in harbors. In the present study it is shown that exposure of S. domuncula to cadmium (CdCl₂) in concentrations ranging from 0.01 to 5.0 g ml⁻¹ for up to 5 d results in apoptotic fragmentation of DNA. Kinetics experiments revealed that after 24 h a significant increase of DNA fragmentation already occurred. Besides cadmium a second stimulus was identified to also cause apoptosis in this species, namely exposure to heat-treated Escherichia coli. In order to support the finding that both cadmium and E. coli induce apoptosis in the sponge, expression of the apoptotic gene MA-3 was studied. The cDNA, SDMA3, was isolated and found to be 2247 nucleotides long. The deduced amino acid sequence (M_r 50 765) shares high similarity with the corresponding mouse molecule. Like the mouse gene, the sponge MA-3 gene undergoes increased expression in response to apoptotic stimuli. While the specimens remained alive after treatment with cadmium, the sponges treated with E. coli died after approximately 12 d. The E. coli-treated animals started to form gemmules 10 to 12 d after addition of the bacteria. Hence, the process of apoptosis in sponges is triggered by two different pathways, one which is initiated by exogenous factors, e.g. heavy metals, and a second one, caused by endogenous factors, which leads to gemmule formation and a shift of the presumably immortal cells to mortal cells. The latter assumption is supported by the finding that during the process of bacteria-induced apoptosis, which results in the death of the specimens, the activity of the telomerase drops. It is concluded that the cells which appear to be immortal and telomerase-positive undergo apoptosis during the process of gemmule formation. In consequence cells not involved in the production of gemmules become mortal. Based on these data, it is proposed that apoptosis is a suitable biomarker in the bioindicator organism S. domuncula to monitor unfavorable environmental conditions, at least in this animal phylum. Received: 10 November 1997 / Accepted: 6 March 1998     

Alteration of photosystem II activity by atrazine on Chlamydomonas reinhardtii synchronized and asynchronized cell cycle cultures

Inhibition of photosystem II (PSII) activity by atrazine was investigated in the green alga Chlamydomonas reinhardtii during different states of the cell cycle. The algal cultures were maintained under continuous light or under light/dark cycle (16/8?h) to obtain homogenized cell cycle distribution. The cycle state of algal population was determined by the DNA content using flow cytometry and defined as newly divided cells before the initiation of DNA replication (G₀/G₁) and cells at the end of the replication cycle with fully duplicated DNA content (G₂/M). Under different synchronized states of the cell population, the photosynthetic activity was investigated after treatment at 10, 100, and 1000?µmol?L^?1 atrazine exposed for 24?h by using fluorescence parameters related to PSII activity measured with a plant efficiency analyzer and pulse-amplitude modulated methods. In this study, we found that the atrazine effect was different depending on cell cycle phases and the period of illumination. Algal cells under light–dark cycle showed inhibition of the PSII electron transport leading to an increase of heat energy dissipation by the PSII reaction center. Algal cells grown under continuous light was shown to be more resistant to atrazine than the cells grown under light–dark cycle.     

The effects of the diarrhetic shellfish poisoning toxins,okadaic acid and dinophysistoxin-1, on the growth of microalgae

The diarrhetic shellfish poisoning toxins okadaic acid (OA) and dinophysistoxin-1 (DTX-1) are potent phosphatase inhibitors produced by certain species of marine dinoflagellates. OA can cause hyperphosphorylation of a broad range of animal and higherpalnt proteins, but little is known regarding the effects of the DSP toxins on marine organisms or their biological function. A variety of microalgae, including a clone ofProrocentrum lima known to produce both OA and DTX-1, were incubated with solutions of OA and in one case DTX-1 or a combination of OA and DTX-1. OA inhibited the growth of all non-DSP-producing test species at micromolar concentrations, butP. lima was not affected even at much higher levels. This differential activity of OA suggests that the DSP toxins may play an allelopathic role and raises questions regarding the strategies adopted by DSP-producing dinoflagellates such asP. lima to avoid autotoxicity. The effects of DTX-1 on microalgal growth were found to be equivalentt to those of OA, and the effects of both toxins in combination were simply additive.     

石油烃对栉孔扇贝血淋巴细胞DNA损伤的初步研究

为研究石油烃对海洋生物的毒性效应,将栉孔扇贝(Chlamys farreri)暴露于0.08、0.21和0.88mg·L-1石油烃中,采用单细胞凝胶电泳实验(彗星实验)技术检测不同暴露时间扇贝血淋巴细胞的DNA损伤程度,对照组中石油烃背景浓度为0.04mg·L-1。结果显示,低浓度(0.08mg·L-1)的石油烃短期(<7d)内即可导致栉孔扇贝血淋巴细胞的DNA损伤,并且随石油烃浓度的增大和暴露时间的延长,DNA损伤程度增加,石油烃浓度达0.88mg·L-1时,DNA损伤程度已非常严重。3d恢复实验后,各浓度组DNA损伤又均有不同程度的恢复。研究表明,彗星实验是检测石油烃对海洋贝类DNA损伤的一种有效手段,贝类血淋巴细胞DNA损伤有望成为石油烃污染的一种生物标志物,用于海洋污染的早期预警监测。     

Iron (Fe2+)-induced toxicity produces morphological and physiological changes in roots in Panax ginseng grown in hydroponics

ABSTRACT

Rusty roots markedly influence on ginseng cultivation, and this phenomenon often attributed to iron (Fe) induced toxicity. To examine the physiological mechanisms underlying Fe-initiated toxicity as evidenced by rusty roots in Panax ginseng, morphological and physiological changes in roots were investigated in hydroponics using Fe²⁺ concentrations of 50 (control), 100, 200, 400 or 600 µM. Compared with control, reddish-brown deposition at the root surface increasingly appeared as Fe²⁺ concentration increased (≥200 µM). The pH also rose as Fe levels were elevated. Higher external Fe²⁺ concentrations produced changes in root organelles and cell structures. Structural alterations in mitochondria due to excess Fe storage, protoplast shrinkage and cell vacuolation as well as formation of central vacuole with deposits in roots were observed. In addition, apparent cell wall thickening, cell wall folding and shrinkage, damage of cell membranes and a large amount of cell debris occurred at higher external Fe²⁺ concentrations (≥400 µM). The Fe²⁺ mediated damage resulting in morphological and physiological changes in ginseng roots was concentration and pH dependent.     

Investigating the potential for different scooter and car exhaust emissions to cause cytotoxic and (pro-)inflammatory responses to a 3D in vitro model of the human epithelial airway

The aim of this study was to compare the cytotoxicity and the (pro-)inflammatory responses of two-stroke (direct injection and carburetor technology) and four-stroke scooter and diesel car exhaust emissions on lung cells in vitro. This was analyzed by exposing a 3D in vitro model of the epithelial airway (consisting of human bronchial epithelial cells (cell line 16HBE14o^?) combined with human whole blood monocyte-derived macrophages and dendritic cells) to physically characterized exhaust emissions. Biological endpoints of cytotoxicity (lactate dehydrogenase release), as well as pro-inflammatory cytokine (tumor necrosis factor (TNF)-α) and inflammatory chemokine (interleukin(IL)-8) stimulation were examined. Two-stroke direct injection scooter exhaust contained the highest particle number concentration and nitrogen oxides (NO _x ) concentrations and the emissions from the two-stroke carburetor scooter contained the highest hydrocarbon and lowest NO _x concentrations. The four-stroke scooter emitted the highest carbon monoxide concentration whereas the cars emitted the lowest. The combination of various technical optimizations for the two-stroke direct injection scooter (particle filter, oxidative catalyst, better oil and fuel) reduced the total emissions strongly and the TNF-α concentration significantly (p?相似文献   

Effects of ellagic acid on arylamine N‐acetyltransferase activity in human colon tumor cells

The inhibition of arylamine N‐acetyltransferase (NAT) activity by ellagic acid was determined in a human colon tumor (adenocarcinoma) cell line. Two assay systems were performed, one with cellular cytosols (9000g supernatant), the other with intact colon tumor cell suspensions. The NAT activity in a human colon tumor cell line was inhibited by ellagic acid in a dose‐dependent manner in both types of examined systems: i.e. the greater the concentration of ellagic acid in the reaction, the greater the inhibition of NAT activities in both systems. The data also indicated that ellagic acid decreased the apparent K _m and V _max of NAT enzymes from human colon tumor cells in both the systems examined. This report is the first demonstration which showed ellagic acid affect human colon tumor cell NAT activity.