RESUMEN
Dual chambered microbial fuel cells with Potassium dichromate (22â¯g/L, MFC-1) and tannery effluent waste water containing 26â¯mg/L (MFC-2), 5â¯mg/L (MFC-3) of Cr(VI) as catholyte, sweet lime waste inoculated by cowdung as anolyte and graphite electrodes were used to reduce toxic Cr(VI) to Cr(III) with simultaneous power generation. Cr (VI) in the cathode chamber reduced to Cr2O3 within 24â¯h. Complete reduction of Cr(VI) from tannery effluents by microbial fuel cell is noticed within 10 days. The 16â¯s rRNA sequencing studies demonstrated presence of Geobacter Metallireducens in mixed culture bacteria in anaerobic anode. The power density of the device is 396.7â¯mW/m2on day1which is 7.2 times higher than literature data of 55.5â¯mW/m2. The processes involved on the biofilm/electrolyte interface and graphite/electrolyte interface is studied by Electrochemical Impedance Spectroscopy. Electrochemical studies demonstrated the active growth of biofilm on anode which reduces charge transfer resistance from day 1 to day 25. The concentration of Cr(VI) reduced in the present studies are approximately 1000 times higher than those reported in the literature.
Asunto(s)
Fuentes de Energía Bioeléctrica , Dicromato de Potasio/metabolismo , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/metabolismo , Bacterias/genética , Bacterias/metabolismo , Fuentes de Energía Bioeléctrica/microbiología , Biopelículas , Cromo/metabolismo , Impedancia Eléctrica , Electrodos/microbiología , Residuos Industriales , Oxidación-Reducción , ARN Ribosómico 16S/genética , Curtiembre , Aguas ResidualesRESUMEN
Sulphate-reducing bacteria Desulfomicrobium sp. CrR3 and Desulfotomaculum. sp. are able to use fumarate as electron donor and acceptor. When they use fumarate as an electron acceptor succinate accumulates in the medium. If fumarate serves as electron donor, minor amounts of citrate, isocitrate and acetate are detected except succinate. In the case of simultaneous introduction of fumarate, SO4(2-) and Cr2O7(2-), the last inhibits usage of fumarate and SO4(2-).
Asunto(s)
Desulfotomaculum/metabolismo , Fumaratos/metabolismo , Técnicas Bacteriológicas , Biomasa , Desulfotomaculum/crecimiento & desarrollo , Transporte de Electrón , Dicromato de Potasio/metabolismo , Sulfatos/metabolismo , Bacterias Reductoras del Azufre/crecimiento & desarrollo , Bacterias Reductoras del Azufre/metabolismoRESUMEN
A bacterial strain was isolated from tannery effluent which can tolerate high concentrations of potassium dichromate up to 1000 ppm. The isolated microorganism was identified as Pseudomonas aeruginosa by performing biochemical tests and molecular characterization. In the presence of excess of carbohydrate source, which is a physiological stress, this strain produces Polyhydroxybutyrate (PHB). This intracellular polymer, which is synthesized, is primarily a product of carbon assimilation and is employed by microorganisms as an energy storage molecule to be metabolized when other common energy sources are limitedly available. Efforts were taken to check whether the PHB has any positive effect on spent wash decolorization. When a combination of PHB and the isolated bacterial culture was added to spent wash, a maximum color removal of 92.77% was found which was comparatively higher than the color removed when the spent wash was treated individually with the PHB and Pseudomonas aeruginosa. PHB behaved as a support material for the bacteria to bind to it and thus develops biofilm, which is one of the natural physiological growth forms of microorganisms. The bacterial growth in the biofilm and the polymer together acted in synergy, adsorbing and coagulating the pollutants in the form of color pigments.
Asunto(s)
Hidroxibutiratos/metabolismo , Poliésteres/metabolismo , Dicromato de Potasio/metabolismo , Pseudomonas aeruginosa/metabolismo , Aguas Residuales/microbiología , Contaminantes Químicos del Agua/metabolismo , Purificación del Agua/métodos , Biodegradación Ambiental , Color , Residuos Industriales/prevención & control , Dicromato de Potasio/aislamiento & purificación , Pseudomonas aeruginosa/clasificación , Pseudomonas aeruginosa/aislamiento & purificación , Curtiembre/métodos , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificaciónRESUMEN
Antecedentes. Psilocybe cubensis es una especie de acción psicodisléptica, que crece sobre estiércol vacuno en praderas de zonas tropicales y subtropicales, consumido en México desde épocas ancestrales tanto con fines ceremoniales y rituales como curativos o medicinales. Artemia franciscana es un crustáceo utilizado con frecuencia como organismo modelo para pruebas de toxicidad. Objetivos. Conocer la toxicidad de P. cubensis, a través de un extracto de esta especie, sobre nauplios y adultos de A. franciscana. Métodos. Los especímenes se recolectaron en la región de Bahía de Banderas, Jalisco, México, se secaron y homogeneizaron en agua de mar artificial. Los bioensayos se realizaron en tubos de ensayo con diferentes concentraciones del extracto de P. cubensis (EAP) y con dicromato de potasio como sustancia tóxica de referencia. Para conocer la toxicidad se calculó la concentración letal media (CL50) en nauplios y adultos y el porcentaje de inhibición de la eclosión de los quistes de A. franciscana. Resultados. Los nauplios presentaron una CL50=135mg/ml, mientras que la de los adultos fue CL50=172mg/ml. El EAP inhibió la eclosión de los quistes en un 100% en todas las concentraciones. Conclusiones. Bajo las condiciones de este estudio, el extracto de P. cubensis resultó tóxico para nauplios y adultos de A. franciscana(AU)
Background. Psilocybe cubensis is a species with psychodysleptic action that grows on cattle dung in pastures in the tropics and subtropics. This fungus has been widely used in Mexico since ancient times both for ceremonies and rituals, as well as for healing or medicinal purposes. Artemia franciscana is a crustacean frequently used as a model organism for toxicity testing. Aims. With the objective of determining the toxicity of P. cubensis, the results of a study with the extract of P. cubensis on nauplii and adults of the brine shrimp A. franciscana are presented. Methods. Specimens were collected at Bahía de Banderas, Jalisco, Mexico, and were dried and homogenized in artificial sea water. Bioassays were carried out on crystal vials filled with different concentrations of the extract of P. cubensis (EAP), and with potassium dichromate as reference toxic compound. The median lethal concentration (LC50) in nauplii and adults and the inhibition of cysts hatching in A. franciscana were calculated. Results. Nauplii showed a LC50=135mg/ml, while adults a LC50=172mg/ml. Cysts hatching was inhibited by the EAP at all tested concentrations. Conclusions. Under the conditions of this study, the extract of P. cubensis was toxic for nauplii and adults of A. franciscana(AU)
Asunto(s)
Psilocybe/aislamiento & purificación , Psilocybe/patogenicidad , Artemia/microbiología , Dicromato de Potasio/síntesis química , Dicromato de Potasio/metabolismo , Dicromato de Potasio/toxicidad , Estiércol/análisis , Estiércol/microbiología , Tarentula cubensis/aislamiento & purificación , Tarentula cubensis/farmacología , Tarentula cubensis/normasRESUMEN
The in situ reduction of Cr (VI) to its less toxic form Cr (III) may be a useful detoxification mechanism for phytoremediation. Using a hydroponics mesocosmos approach, we evaluated the ability of Halimione portulacoides to reduce and uptake Cr (VI) and its anti-oxidative feedback and biomarkers. It was found that this specie can, not only reduce large amounts of Cr (VI) in the external medium, but also withdrawn and accumulate this element in its roots and aboveground organs. Both these mechanisms were found to be dose dependent. Jointly with this phytoremediative potential the oxidative feedback was also assessed. Chromium uptake had its major implications on the chlorophyll content and flavonoid content, with potential consequences in the photosynthetic and photo-protective mechanisms. Although the high Cr root accumulation in H. portulacoides, there were no inactivation of the enzymatic defenses, allowing a continuous defense against reactive oxygen species. In fact, GPX and specially SOD revealed to be an excellent dose-related biomarker of Cr induced stress. All these aspects make this specie suitable for Cr (VI) phytoremediation processes, either by phytoextraction or by reduction of Cr (VI) to Cr (III) and also for monitoring programs using SOD and GPX as biomarkers of Cr environmental contamination.
Asunto(s)
Amaranthaceae/metabolismo , Biomarcadores/metabolismo , Cromo/metabolismo , Amaranthaceae/química , Amaranthaceae/enzimología , Biodegradación Ambiental , Biomarcadores/análisis , Carotenoides/análisis , Clorofila/análisis , Flavonoides/análisis , Peroxidación de Lípido , Oxidación-Reducción , Oxidorreductasas/metabolismo , Fotosíntesis , Hojas de la Planta/química , Dicromato de Potasio/metabolismo , Especies Reactivas de Oxígeno/análisisRESUMEN
Chromium compounds are known to be associated with cytotoxicity and carcinogenicity when applied via a skin route. The aim of this study was to evaluate the skin permeability and toxicological profiles of four chromium species. Chromium permeation across the skin, as determined by an in vitro Franz cell, decreased in the order of sodium chromate>potassium chromate>potassium dichromate>chromium nitrate. The uptake of chromium species within the skin generally showed a contrary trend to the results of permeation, although differences among the various compounds were not large. Levels of in vivo skin deposition of the four compounds showed no statistically significant differences. Potassium chromate produced the greatest disruption of the skin structure as determined by HE staining, followed in order by sodium chromate, potassium dichromate, and chromium nitrate. This indicates that hexavalent chromium elicited greater toxicity to the skin compared to trivalent chromium. A similar result was observed for the viability of skin fibroblasts. To improve our understanding of the molecular mechanisms leading to functional changes in proteins, proteomic tools, including 2-DE and MS techniques combined with sequence database correlations, were applied to identify target proteins altered by pathologic states. Eight protein spots, corresponding to cutaneous enzymes involved in energy metabolism and chaperon proteins, which were identified and discussed in this study, were associated with skin cytotoxicity, immunity, and carcinogenesis. In addition, functional proteomics of skin tissues may provide a promising tool for developing therapeutic strategies and can serve as the basis for further research.
Asunto(s)
Compuestos de Cromo/metabolismo , Proteómica , Absorción Cutánea , Piel/metabolismo , Animales , Células Cultivadas , Cromatos/metabolismo , Electroforesis en Gel Bidimensional , Femenino , Inmunohistoquímica , Técnicas In Vitro , Queratinas/metabolismo , Ratones , Nitratos/metabolismo , Compuestos de Potasio/metabolismo , Dicromato de Potasio/metabolismo , Compuestos de Sodio/metabolismo , Espectrometría de Masa por Láser de Matriz Asistida de Ionización DesorciónRESUMEN
Potassium dichromate (K2Cr2O7) is a soluble hexavalent chromium compound that is widely used in several industries. In the present work the effect of administration of K2Cr2O7 on rat intestinal brush border membrane(BBM) enzymes and anti-oxidant system was studied. Rats were given a single oral dose of K2Cr2O7 (100 mg/kg bodyweight) and sacrificed 6, 12, 24, 48 and 96 h after the treatment.Control animals were not given K2Cr2O7. The administration of K2Cr2O7 resulted in a reversible decline in the specific activities of several BBM enzymes. The decrease in the activities of these enzymes was due to changes in the maximum velocity while their affinities for the substrates remained unchanged. Lipid peroxidation increased while total SH groups decreased in K2Cr2O7-treated rats as compared to controls indicating increased oxidative stress in the intestinal mucosa. The activities of superoxide dismutase and glutathione-S-transferase increased while those of catalase, glutathione reductase, thioredoxin reductase and glucose-6-phosphate dehydrogenase decreased. The maximum changes in all the parameters studied above were 24 h after administration of K2Cr2O7 after which recovery took place,in most cases almost to control values after 96 h. These results show that oral administration of K2Cr2O7 to decrease in the activities of BBM enzymes, increase in oxidative stress and alters the activities of anti-oxidant enzymes in rat intestine.
Asunto(s)
Antioxidantes/metabolismo , Mucosa Intestinal/efectos de los fármacos , Intestinos/efectos de los fármacos , Microvellosidades/efectos de los fármacos , Dicromato de Potasio/farmacología , Administración Oral , Fosfatasa Alcalina/análisis , Animales , Antioxidantes/farmacología , Glucosafosfato Deshidrogenasa/análisis , Glutatión Reductasa/análisis , Glutatión Transferasa/análisis , Hidrólisis , Mucosa Intestinal/enzimología , Mucosa Intestinal/metabolismo , Intestinos/enzimología , Cinética , Leucil Aminopeptidasa/análisis , Masculino , Malondialdehído/análisis , Microvellosidades/enzimología , Microvellosidades/metabolismo , Dicromato de Potasio/administración & dosificación , Dicromato de Potasio/metabolismo , Ratas , Ratas Wistar , Especificidad por Sustrato , Sacarasa/análisis , Compuestos de Sulfhidrilo/análisis , Superóxido Dismutasa/análisis , Reductasa de Tiorredoxina-Disulfuro/análisis , gamma-Glutamiltransferasa/análisisRESUMEN
Hexavalent chromium (Cr VI) is a highly toxic metal and an environmental pollutant. Different studies indicate that Cr VI exposure adversely affects reproductive functions. This metal has been shown to affect several tissues and organs but Cr VI effects on pituitary gland have not been reported. Anterior pituitary hormones are central for the body homeostasis and have a fundamental role in reproductive physiology. The aim of this study was to evaluate the effect of Cr VI at the pituitary level both in vivo and in vitro. We showed that Cr VI accumulates in the pituitary and hypothalamus, and decreases serum prolactin levels in vivo but observed no effects on LH levels. In anterior pituitary cells in culture, the effect of Cr VI on hormone secretion followed the same differential pattern. Besides, lactotrophs were more sensitive to the toxicity of the metal. As a result of oxidative stress generation, Cr VI induced apoptosis evidenced by nuclear fragmentation and caspase 3 activation. Our results indicate that the anterior pituitary gland can be a target of Cr VI toxicity in vivo and in vitro, thus producing a negative impact on the hypothalamic-pituitary-gonadal axis and affecting the normal endocrine function.
Asunto(s)
Apoptosis/efectos de los fármacos , Contaminantes Ambientales/toxicidad , Gonadotropinas Hipofisarias/metabolismo , Adenohipófisis/efectos de los fármacos , Dicromato de Potasio/toxicidad , Acetilcisteína/farmacología , Animales , Antioxidantes/farmacología , Caspasa 3/metabolismo , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Cromo/toxicidad , Relación Dosis-Respuesta a Droga , Contaminantes Ambientales/metabolismo , Activación Enzimática/efectos de los fármacos , Gonadotropinas Hipofisarias/sangre , Hipotálamo/metabolismo , Hígado/metabolismo , Hormona Luteinizante/metabolismo , Masculino , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Adenohipófisis/metabolismo , Adenohipófisis/patología , Dicromato de Potasio/metabolismo , Prolactina/metabolismo , Ratas , Ratas Wistar , Especies Reactivas de Oxígeno/metabolismo , Factores de TiempoRESUMEN
To identify a sensitive biomarker of freshwater monitoring, we evaluated pollutant-induced expression of heat shock proteins (HSPs) and hemoglobins (Hbs) genes in the larvae of the aquatic midge Chironomus tentans (Diptera, Chironomidae). As pollutants, we examined nonylphenol, bisphenol-A, 17alpha-ethynyl estradiol, bis(2-ethylhexyl) phthalate, endosulfan, paraquat dichloride, chloropyriphos, fenitrothion, cadmium chloride, lead nitrate, potassium dichromate, benzo[a]pyrene and carbon tetrachloride. We also investigated larval growth as a physiological descriptor by measuring changes in the body fresh weight and dry weight after chemical exposure. The response of the HSPs gene expression by chemical exposure was rapid and sensitive to low chemical concentrations but it was not stressor specific. Interestingly, an increase in the expression of HSPs genes was observed not only in a stress inducible form (HSP70), but also in a constitutively (HSC70) expressed form. The expression of Hb genes showed chemical-specific responses: that is, alkyl phenolic compounds increased the expression of hemoglobin genes, whereas pesticides decreased the expression. As expected, molecular-level markers were more sensitive than physiological endpoints, suggesting that gene expression could be developed as an early warning biomarker in this animal. The overall results suggest that the expression of HSP and Hb genes in Chironomus could give useful information for diagnosing general health conditions in fresh water ecosystem. The expression of Hb genes, in particular, seems to be a promising biomarker, especially in view of the potential of Chironomus larvae as a biomonitoring species and of the physiological particularities of their respiratory pigments.
Asunto(s)
Chironomidae/fisiología , Agua Dulce/análisis , Regulación de la Expresión Génica/efectos de los fármacos , Proteínas de Choque Térmico/genética , Hemoglobinas/genética , Larva/efectos de los fármacos , Contaminantes Químicos del Agua , Animales , Benzo(a)pireno/análisis , Benzo(a)pireno/metabolismo , Benzo(a)pireno/toxicidad , Biomarcadores/análisis , Cloruro de Cadmio/análisis , Cloruro de Cadmio/metabolismo , Cloruro de Cadmio/toxicidad , Tetracloruro de Carbono/análisis , Tetracloruro de Carbono/metabolismo , Tetracloruro de Carbono/toxicidad , Chironomidae/genética , Cloropirifos/análisis , Cloropirifos/metabolismo , Cloropirifos/toxicidad , Dietilhexil Ftalato/análisis , Dietilhexil Ftalato/metabolismo , Dietilhexil Ftalato/toxicidad , Endosulfano/análisis , Endosulfano/metabolismo , Endosulfano/toxicidad , Monitoreo del Ambiente , Etinilestradiol/análisis , Etinilestradiol/metabolismo , Etinilestradiol/toxicidad , Fenitrotión/análisis , Fenitrotión/metabolismo , Fenitrotión/toxicidad , Agua Dulce/química , Proteínas de Choque Térmico/metabolismo , Hemoglobinas/metabolismo , Larva/crecimiento & desarrollo , Plomo/análisis , Plomo/metabolismo , Plomo/toxicidad , Nitratos/análisis , Nitratos/metabolismo , Nitratos/toxicidad , Fenoles/análisis , Fenoles/metabolismo , Fenoles/toxicidad , Dicromato de Potasio/análisis , Dicromato de Potasio/metabolismo , Dicromato de Potasio/toxicidad , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/metabolismo , Contaminantes Químicos del Agua/toxicidadRESUMEN
In this paper, dichromate and dichlorvos are selected as the deputies of inorganic and organic pollutants, respectively, and TiO2/beads is used as a photocatalyst. The effects of various parameters, such as the amount of the photocatalyst, H2O2 concentration, metal ions, anions, pH value, and organic compounds on the photocatalytic reduction of dichromate and photocatalytic oxidation of dichlorvos are studied. From the studies, the differences of the parameters effect on the photocatalytic degradation of organic and inorganic pollutants are obtained. The results show that the optimum amount of the photocatalyst used is 6.0 g cm(-3) for the photocatalytic reactions. With the addition of a small amount of H2O2, the photocatalytic reduction of dichromate is inhibited while the photocatalytic oxidation of dichlorvos is accelerated. With the addition of trace amounts of Fe3+ or Cu2+, both the reactions are accelerated, and with the addition of Zn2+ and Na+, no obvious effects on the reactions are observed. Acidic solution is favorable for the photocatalytic reduction of dichromate; and acidic and alkaline solutions are favorable for the photocatalytic oxidation of dichlorvos. Adding SO4(2-), the photocatalytic oxidation is accelerated and adding Cl- the reaction is inhibited; and with the addition of trace amounts of SO4(2-), Cl- and NO3-, no obvious effects on the photocatalytic reduction of dichromate are observed. With the addition of methanol and toluene, the photocatalytic reduction of dichromate is accelerated, and the photocatalytic oxidation of dichlorvos is inhibited. The possible roles of the additives on the reactions are also discussed.
Asunto(s)
Diclorvos/metabolismo , Dicromato de Potasio/metabolismo , Titanio/química , Contaminantes Químicos del Agua/metabolismo , Purificación del Agua/métodos , Catálisis , Cationes , Cloruros/química , Cobre/química , Diclorvos/aislamiento & purificación , Peróxido de Hidrógeno/química , Concentración de Iones de Hidrógeno , Insecticidas/aislamiento & purificación , Insecticidas/metabolismo , Hierro/química , Nitratos/química , Compuestos Orgánicos/química , Oxidación-Reducción , Fotoquímica , Sodio/química , Sulfatos/química , Contaminantes Químicos del Agua/aislamiento & purificación , Zinc/químicaRESUMEN
Extensive use of hexavalent chromium [Cr(VI)] in various industrial applications has caused substantial environmental contamination. Chromium-resistant bacteria isolated from soils can be used to remove toxic Cr(VI) from contaminated environments. This study was conducted to isolate chromium-resistant bacteria from soils contaminated with dichromate and describes the effects of some environmental factors such as pH, temperature, and time on Cr(VI) reduction and resistance. We found that chromium-resistant bacteria can tolerate 2500 mg L(-1) Cr(VI), but most of the isolates tolerated and reduced Cr(VI) at concentrations lower than 1500 mg L(-1). Chromate reduction activity of whole cells was detected in five isolates. Most of these isolates belong to the genus Bacillus as identified by the 16S rRNA gene sequencing. Maximal Cr(VI) reduction was observed at the optimum pH (7.0-9.0) and temperature (30 degrees C) of growth. One bacterial isolate (Bacillus sp. ES 29) was able to aerobically reduce 90% of Cr(VI) in six hours. The Cr(VI) reduction activity of the whole cells of five isolates had a K(M) of 0.271 (2.61 mM) to 1.51 mg L(-1) (14.50 mM) and a V(max) of 88.4 (14.17 nmol min(-1)) to 489 mg L9-1) h(-1) (78.36 nmol min(-1)). Our consortia and monocultures of these isolates can be useful for Cr(VI) detoxification at low and high concentrations in Cr(VI)-contaminated environments and under a wide range of environmental conditions.
Asunto(s)
Carcinógenos Ambientales/metabolismo , Cromo/metabolismo , Colorantes/metabolismo , Dicromato de Potasio/metabolismo , Microbiología del Suelo , Contaminantes del Suelo/metabolismo , Bacillus/genética , Bacillus/fisiología , Contaminación Ambiental/prevención & control , Oxidación-Reducción , ARN Ribosómico 16S/análisisRESUMEN
The response of Schizosaccharomyces pombe towards the oxyanions selenate [Se(VI)] and dichromate [Cr(VI)] was investigated in order to establish the involvement of the yeast ATP sulfurylase in their reduction. An ATP sulfurylase-defective/selenate-resistant mutant of S. pombe (B-579 Se(R) -2) and an ATP sulfurylase-active/selenate-sensitive strain of S. pombe (B-579 Se(S)) were included in this study. The inhibitory effect of Se(VI) and Cr(VI) oxyanions on growth and bioaccumulation was measured. The sensitive strain showed natural sensitivity to selenate while the resistant mutant tolerated a 100-fold higher concentration of selenate. These results indicate that selenate toxicity to microorganisms is connected with the reduction of selenate to selenite. Both strains showed similar sensitivity to Cr(VI) and in this study there was no evidence that ATP sulfurylase participates in the reduction process of Cr(VI).
Asunto(s)
Dicromato de Potasio/metabolismo , Schizosaccharomyces/enzimología , Compuestos de Selenio/metabolismo , Sulfato Adenililtransferasa/metabolismo , Biomasa , Mutagénesis , Schizosaccharomyces/metabolismo , Ácido SelénicoRESUMEN
Batch studies were conducted on degradation of anaerobically digested distillery wastewater by three bacterial strains, viz. Xanthomonas fragariae, Bacillus megaterium and Bacillus cereus in free and immobilized form, isolated from the activated sludge of a distillery wastewater treatment plant. The removal of COD and colour with all the three strains increased with time up to 48 hr and only marginal increase in COD and colour removal efficiency was observed beyond this period up to 72 hr. After this period removal efficiency remained fairly constant up to 120 hr. The maximum COD and colour removal efficiency varied from 66 to 81% and 65 to 75%, respectively for both free and immobilized cells of all the three strains. The strain Bacillus cereus showed the maximum efficiency of COD (81%) and colour (75%) removal out of the three strains. An interrelationship between the percent COD and colour removal was carried out by correlation and regression analysis and was justified by high values of coefficient of correlation (r = 0.99) for all the cases. The first order removal rate kinetics was also applied and rate constants were evaluated for COD and colour removal efficiencies.
Asunto(s)
Bebidas Alcohólicas , Bacillus cereus/metabolismo , Bacillus megaterium/metabolismo , Residuos Industriales , Contaminantes Químicos del Agua/metabolismo , Xanthomonas/metabolismo , Alginatos/química , Alginatos/metabolismo , Bacillus cereus/aislamiento & purificación , Bacillus megaterium/aislamiento & purificación , Biodegradación Ambiental , Portadores de Fármacos/química , Portadores de Fármacos/metabolismo , Ácido Glucurónico , Ácidos Hexurónicos , Microbiología Industrial/métodos , Dicromato de Potasio/metabolismo , Factores de Tiempo , Eliminación de Residuos Líquidos/métodos , Xanthomonas/aislamiento & purificaciónRESUMEN
Incubation of primary cultures of rat hepatocytes with K2CR2O7 and deferoxamine (DFO), an iron chelator, resulted in a marked decrease in cellular levels of DNA single-strand breaks caused by K2Cr2O7. Cellular treatment with DFO also suppressed both dichromate-induced cytotoxicity--evaluated by the leakage of lactate dehydrogenase, and lipid peroxidation--as monitored by malondialdehyde formation. In addition, treatment with DFO attenuated the suppression of the levels of vitamin E and C as well as the inhibition of alkaline phosphatase and glutathione peroxidase activity attributed to K2Cr2O7. However, DFO had no influence on the cellular level of glutathione or the activity of glutathione reductase and superoxide dismutase suppressed by dichromate. Under the same experimental conditions, cellular uptake and distribution of chromium were not affected by DFO. These results indicate that DFO protects cells from chromium (VI)-induced DNA strand breaks, cytotoxicity, lipid peroxidation, vitamin E and C depression, and glutathione peroxidase inhibition The role of antioxidants in chromium (VI)-induced cytotoxicity, DNA breaks, and lipid peroxidation is discussed.
Asunto(s)
Antídotos/farmacología , Daño del ADN/efectos de los fármacos , ADN de Cadena Simple/efectos de los fármacos , Deferoxamina/farmacología , Peroxidación de Lípido/efectos de los fármacos , Hígado/efectos de los fármacos , Fosfatasa Alcalina/antagonistas & inhibidores , Fosfatasa Alcalina/metabolismo , Animales , Ácido Ascórbico/metabolismo , Cáusticos/metabolismo , Cáusticos/toxicidad , Células Cultivadas , ADN de Cadena Simple/genética , Relación Dosis-Respuesta a Droga , Glutatión/metabolismo , Glutatión Peroxidasa/antagonistas & inhibidores , Glutatión Peroxidasa/metabolismo , Glutatión Reductasa/metabolismo , L-Lactato Deshidrogenasa/metabolismo , Hígado/citología , Hígado/enzimología , Masculino , Malondialdehído/metabolismo , Dicromato de Potasio/metabolismo , Dicromato de Potasio/toxicidad , Ratas , Ratas Wistar , Superóxido Dismutasa/metabolismo , Vitamina E/metabolismoRESUMEN
Although studies in chemical and biological systems have demonstrated that free radical formation is mediated by Cr(VI), no ESR evidence for the generation of free radicals in vivo has been reported. We have employed an ESR spin-trapping technique to detect an adduct of the spin trap alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone (4-POBN) in the bile of animals given an intragastric dose of potassium dichromate. In this study, we provide evidence for in vivo radical generation resulting from Cr(VI)-poisoned rats. Upon the administration of Cr(VI) and 4-POBN, the ESR spectrum of the radical adducts present in the bile exhibited hyperfine coupling constants aN = 15.71 G and a beta H = 2.90 G. We suggest that the radical responsible for this 4-POBN adduct is carbon-centered and derived from endogenous lipids. The radical adducts detected in the bile from Cr(VI)-treated rats are proposed to be formed and trapped in the liver and excreted into bile. This is the first report of electron spin resonance evidence for the in vivo generation of free radicals by Cr(VI).
Asunto(s)
Dicromato de Potasio/metabolismo , Alanina Transaminasa/sangre , Animales , Bilis/metabolismo , Espectroscopía de Resonancia por Spin del Electrón , Radicales Libres/metabolismo , L-Lactato Deshidrogenasa/sangre , Hígado/metabolismo , Masculino , Óxidos de Nitrógeno/farmacología , Piridinas , Ratas , Ratas Sprague-DawleyRESUMEN
A comparative study has been made on the mechanisms of toxicities of trivalent and hexavalent forms of chromium in Neurospora crassa. Of the two forms, Cr6+ is more toxic than Cr3+. The toxicity of Cr3+ was found to be due to its specific antagonism with iron uptake. Fe3+ was found to be very effective in reversing the toxicity of Cr3+ by concomitantly suppressing its uptake. That the Cr3+ toxicity caused a conditional intracellular iron deficiency was indicated by the decrease in the activities of catalase and uricase and a progressive increase in the excretion of iron binding compound into the medium. The toxicity of Cr6+ (as Cr2O7(2-)) was found to be due to its specific antagonism of sulfate uptake. Methionine was found to be more effective in reversing dichromate toxicity than sulfate, probably by repressing the synthesis of sulfate permeases responsible for dichromate (Cr6+) uptake. Maximal uptake of Cr6+ was nearly tenfold lower and Vmax much higher than that of Cr3+. Evidence has been adduced to show that Cr6+ and Cr3+ were toxic by themselves and that interconversion between the tri- and hexavalent forms of chromium did not occur to any detectable extent.
Asunto(s)
Cromo/toxicidad , Neurospora crassa/efectos de los fármacos , Transporte Biológico/efectos de los fármacos , Catalasa/metabolismo , Cromo/antagonistas & inhibidores , Relación Dosis-Respuesta a Droga , Hierro/metabolismo , Hierro/farmacología , Neurospora crassa/crecimiento & desarrollo , Neurospora crassa/metabolismo , Dicromato de Potasio/metabolismo , Dicromato de Potasio/toxicidad , Urato Oxidasa/metabolismoRESUMEN
The effects of several thiol compounds on the cytotoxicity induced by chromate (potassium dichromate) were examined. HeLa cells were incubated in Eagle's minimum essential medium (MEM) with or without the chromate alone, or with both chromate and any one of L-cysteine ethyl ester (LCysEE), L-cysteine methyl ester (LCysME), N-acetyl-L-(+)-cysteine, 2,3-dimercaptosuccinic acid (DMSA), 2, 3-dimercapto-1-propanesulfonic acid (DMPS), or dithiothreitol. After a given period of incubation, the number of viable cells was counted using the trypan blue exclusion test and the chromium content of the cells was estimated by atomic absorption spectrophotometry. The results obtained were as follows. 1) Chromate-induced cytotoxicity evaluated by inhibition of cell growth at 3 days of incubation was diminished by all of the thiol compounds tested when the cells were incubated in MEM with 2.5 to 10.0 microM chromate and 25 to 100 microM thiol compounds. 2) All of the thiol compounds produced a concentration-dependent reduction of chromate when a solution of the thiol compound (12.5 to 100 microM) was mixed with a solution of chromate (10 microM) in distilled water. 3) When cells were incubated in MEM with both 10 microM chromate and 25 to 100 microM thiol compounds, the chromium content of the cells at 6 hr of incubation was decreased in a concentration-dependent manner. 4) When these thiol compounds were added to MEM 1 hr before or after chromate, no or little protective effects of these thiol compounds against chromate-induced cytotoxicity and chromium uptake by the cells were observed.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
División Celular/efectos de los fármacos , Dicromato de Potasio/toxicidad , Compuestos de Sulfhidrilo/farmacología , Medios de Cultivo , Interacciones Farmacológicas , Células HeLa , Humanos , Oxidación-Reducción , Dicromato de Potasio/metabolismoRESUMEN
In order to study the difference of uptake and distribution between hexavalent (Cr6+) and trivalent (Cr3+) chromium in isolated rat hepatocytes, the cells were incubated with Cr6+ or Cr3+ (1 mM Cr) at 37 degrees C for up to 60 min. Leakage of lactate dehydrogenase from the hepatocytes into the suspension medium as an indicator of cellular injury was facilitated by Cr6+ (K2Cr2O7) at 60 min of incubation, whereas Cr3+ [Cr(NO3)3] had no effect. After 60 min of incubation with Cr6+, about 33% of the added Cr was found in the hepatocytes, whereas incubation with Cr3+ resulted in transfer of about 66% of the added Cr to the cells. After 20 and 40 min of incubation with Cr6+, about 39% of cellular Cr was found in the cytosolic fraction of hepatocytes, followed by a reduction to about 35% after 60 min of incubation. However, Cr detected in the cytosolic fraction of hepatocytes incubated with Cr3+ was about 1% of cellular Cr. Cr-binding substances in the cytosolic fraction of hepatocytes incubated with Cr6+ were eluted with two Cr peaks by Sephadex G-200 chromatography. These Cr-binding substances in the low-molecular-weight fractions were separable into at least two substances by thin-layer chromatography. These results suggest that Cr6+ readily passes through the cell membrane and combines with substances already present in the cytosolic fraction of hepatocytes, unlike metallothionein induced by cadmium, followed by detoxification. Consequently, cellular injury might be induced by Cr6+ which could not combine with LMCr in the cytosolic space of the hepatocytes.
Asunto(s)
Compuestos de Cromo , Cromo/metabolismo , Hígado/metabolismo , Nitratos/metabolismo , Dicromato de Potasio/metabolismo , Animales , Transporte Biológico , Permeabilidad de la Membrana Celular/efectos de los fármacos , Células Cultivadas , Cromo/farmacología , Citosol/química , L-Lactato Deshidrogenasa/análisis , Hígado/efectos de los fármacos , Masculino , Nitratos/farmacología , Dicromato de Potasio/farmacología , Ratas , Ratas Endogámicas , Fracciones Subcelulares/químicaRESUMEN
Comparative effects of hexavalent (K2Cr2O7:Cr(VI)) and trivalent chromium (Cr(NO3)3:Cr(III)) on the development of lipid peroxidation, and the relationship between the lipid peroxidation and damage to tissues were studied using male ddY strain mice. The animals were administered with either of two chemicals at a dose of 20 mg Cr/kg by a single intraperitoneal injection. The results obtained were as follows: (1) Lipid peroxidation in the liver, as measured by the synthesis of thiobarbituric acid reactive substances (TBARS), showed a significant increase at 24 and 48 hr after Cr(VI) injection, while in the kidney it was observed only at 48 hr. In the mice administered with Cr(III), TBARS formation in the liver went down below the control levels, while no change was observed in the kidney. (2) Chromium contents in the liver and kidney showed a maximum level at 6 hr after injection of Cr(VI) and then those declined to the half of the maximum level at 48 hr, respectively. Chromium contents in the liver and kidney of the mice injected with Cr(III) were lower than those injected with Cr(VI) during the experimental period. (3) Increases of TBARS formation in the liver, chromium content in the liver and kidney, and ornithine carbamyl transferase (OCT) activity indicative of the liver cell damage, and urea nitrogen content in the serum, indicative of the kidney damage, observed at 24 hr after injection of Cr(VI) were inhibited by simultaneous injection of 100 mg/kg of L-ascorbic acid, as antichrome agent, respectively. These observations might suggest a possible causative role of lipid peroxidation in Cr(VI) toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Cromatos/metabolismo , Compuestos de Cromo , Cromo/metabolismo , Peroxidación de Lípido , Ratones/metabolismo , Nitratos/metabolismo , Dicromato de Potasio/metabolismo , Animales , Ácido Ascórbico/farmacología , Cromo/toxicidad , Riñón/efectos de los fármacos , Riñón/metabolismo , Hígado/metabolismo , Masculino , Nitratos/toxicidad , Nitrógeno/sangre , Nitrógeno/farmacología , Fenilendiaminas/farmacología , Dicromato de Potasio/toxicidad , Tiobarbitúricos/metabolismoRESUMEN
Trout liver mitochondria were incubated in the presence of micromolar concentration of potassium dichromate (Cr(VI)) under several experimental conditions. Cr(VI) strongly inhibited both state 3 and state 4 of respiration supplemented by NAD-linked substrates; it also slightly affected the respiration of FAD-linked substrates. Evidence is provided that the respiratory inhibition induced by dichromate is partially coupled to the Cr(VI) reduction mechanism occurring in mitochondria.