RESUMEN
A total of 39 lower brominated PBDE congeners in surface soils from the Yellow River Delta Natural Reserve (YRDNR) were analyzed in the present study. The total concentrations of PBDEs (ΣPBDEs) ranged from "not detected" to 0.732 ng g-1, with a mean concentration of 0.142 ng g-1. The concentrations of the ΣPBDEs displayed no correlation with the content of the total organic carbon in the YRDNR. The ΣPBDEs concentrations in the Experimental Area were significantly higher than that of the Buffer Area and Core Area, and ΣPBDEs in soils in the North were lower than that of the South. PentaBDEs and HexaBDEs were the most abundant homologues, and the occurrence of PBDEs in the YRDNR may be attributed to the debromination and long range transport of DecaBDEs. Even though the cancer risk and mass inventory of PBDEs in the present study area were estimated to be very low, due to the widespread presence of PBDEs and the particularity of the natural reserve, vigilance should not be let up on the issue of environmental contamination caused by these compounds despite the gradual phase out of their commercial products in the world.
Asunto(s)
Éteres Difenilos Halogenados/análisis , Contaminantes del Suelo/análisis , Carcinógenos Ambientales/análisis , Carcinógenos Ambientales/toxicidad , China , Conservación de los Recursos Naturales , Monitoreo del Ambiente , Retardadores de Llama/análisis , Éteres Difenilos Halogenados/toxicidad , Humanos , Medición de Riesgo , Contaminantes del Suelo/toxicidadRESUMEN
A total of 28 PCB congeners were determined using gas chromatography-mass spectrometry (GC-MS) in 46 surface soils collected from the Yellow River Delta Natural Reserve (YRDNR) and its adjacent area, China. The total concentrations of PCBs in the YRDNR ranged from 0.149 to 4.32 ng/g, with a mean concentration of 0.802 ng/g. Light PCB congeners predominated in the present research area, which may be attributed to the atmospheric transportation and were also associated with the recent contamination of unintentionally produced PCBs from industrial processes. In addition, PCB 126 and PCB 169 were found to be the major toxicity contributors of dioxin-like PCBs in the YRDNR, which should require special focus.
Asunto(s)
Bifenilos Policlorados/análisis , Ríos/química , Contaminantes del Suelo/análisis , Suelo/química , China , Monitoreo del Ambiente/métodos , Cromatografía de Gases y Espectrometría de Masas , Bifenilos Policlorados/química , Medición de Riesgo , Contaminantes del Suelo/químicaRESUMEN
A series of substituted 9-methylenylanthracene photocages for diphenylphosphinothioesters have been synthesized to explore their photo-uncaging properties by visible light. Substituents such as phenyl, p-trifluoromethylphenyl, p-methoxyphenyl, ethyn-1-ylbenzene, and 3,3-dimethylbut-1-yn-1-yl have been introduced in order to extend the π-conjugation of the photocage and to shift the wavelength response of the uncaging process to the visible spectral range. Among these new photocages, the (10-(3,3-dimethylbut-1-yn-1-yl)anthracen-9-yl)methyl has been shown to have the best performance in terms of fast photo-uncaging and minimal byproduct formation. It is responsive to both UV and visible photoexcitation. Quantum yields of the photoinduced heterolytic anthracenylmethyl-phosphorus bond cleavage at 366 and 416 nm were found to be 0.08 and 0.025, respectively. This photocage enables traceless Staudinger ligation to be triggered by photoirradiation in the visible spectral range for bioconjugation applications. We demonstrate this with a series of visible-light-induced oligopeptide syntheses via the conjugation of amino acid/oligopeptide building blocks by the characteristic peptide linkage attained by traceless Staudinger ligation. Yields of the resultant conjugated oligopeptides ranged from 31 to 43%. This new photocage opens up the possibility of in situ synthesis of functional proteins/peptides mediated by visible-light-induced photoclick processes for the regulation of cellular/metabolic functions of life systems.
RESUMEN
Intracellular delivery of foreign DNA probes sharply increases the efficiency of various biodetection protocols. Spherical nucleic acid (SNA) conjugate is a new type of probe that consists of a dense oligonucleotide shell attached typically to a gold nanoparticle core. They are widely used as novel labels for in vitro biodetection and intracellular assay. However, the degradation of foreign DNA still remains a challenge that can cause significant signal leakage (false positive signal). Hence, the site and behavior of intracellular degradation need to be investigated. Herein, we discover a localized degradation behavior that only excises the first nucleotide of 5' terminal from a DNA strand, whereas the residual portion of this strand is unbroken in MCF-7 cell. This novel degradation action totally differs from previous opinion that foreign DNA strand would be digested into tiny fragments or even individual nucleotides in cellular environment. On the basis of these findings, we propose a simple and effective way to avoid degradation-caused false positive that one can bypass the degradable site and choose a secure region to label fluorophore along the DNA stand, when using DNA probes for intracellular biodetection.
Asunto(s)
Sondas de ADN/genética , ADN/genética , Hibridación de Ácido Nucleico/genética , Oligonucleótidos/genética , Sondas de ADN/química , Oro/química , Humanos , Células MCF-7 , Nanopartículas/química , Nucleótidos/química , Oligonucleótidos/químicaRESUMEN
The simultaneous profiling of 43 functional metabolites in the brain of the small model vertebrate organism, marine medaka (Oryzais melastigma), has been accomplished via dansyl chloride derivatization and LC-MS/MS quantification. This technique was applied to examine effects of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), one of the most abundant polybrominated diphenyl ether flame retardants in the natural environment, on the central nervous system (CNS) of vertebrates. The model teleosts were fed with bioencapsulated Artemia nauplii for up to 21 days. Multivariate statistical analysis has demonstrated that levels of numerous classical neurotransmitters and their metabolites in the CNS of the fish were perturbed even at the early phase of dietary exposure. Subsequent metabolic pathway analysis further implied potential impairment of the arginine and proline metabolism; glycine, serine and threonine metabolism; D-glutamine and D-glutamate metabolism; alanine, aspartate, and glutamate metabolism; valine, leucine, and isoleucine biosynthesis, and the cysteine and methionine metabolism in the brain of the test organism. Our results demonstrate that targeted profiling of functional metabolites in the CNS may shed light on how the various neurological pathways of vertebrates, including humans, are affected by toxicant/stress exposure.
Asunto(s)
Éteres Difenilos Halogenados/toxicidad , Neurotransmisores/metabolismo , Oryzias/metabolismo , Pruebas de Toxicidad/veterinaria , Contaminantes Químicos del Agua/toxicidad , Animales , Sistema Nervioso Central/efectos de los fármacos , Cromatografía Liquida/veterinaria , Compuestos de Dansilo/química , Retardadores de Llama/toxicidad , Espectrometría de Masas en Tándem/veterinaria , Pruebas de Toxicidad/métodosRESUMEN
This study aimed to develop a photoresponsive molecularly imprinted hydrogel (MIH) casting membrane for the determination of trace tetracycline (TC) in milk. This MIH casting membrane combined the specificity of MIHs, the photoresponsive properties of azobenzene, and the portable properties of a membrane. Photoresponsive TC-imprinted MIHs were initially fabricated and then cast on sodium dodecyl sulfonate polyacrylamide gel. After TC removal, a photoresponsive MIH casting membrane was obtained. The photoresponsive properties of the MIH casting membrane were robust, and no obvious photodegradation was observed after 20 cycles. The MIH casting membrane displayed specific affinity to TC upon alternate irradiation at 365 and 440 nm; it could quantitatively uptake and release TC. The TC concentration (0.0-2.0 × 10(-4) mol l(-1)) in aqueous solution displayed a linear relationship with the photoisomerization rate constant of azobenzene within the MIH casting membrane. As such, a quick detection method for trace TC in aqueous foodstuff samples was established. The recovery of this method for TC in milk was investigated with a simple pretreatment of milk, and a high recovery of 100.54-106.35% was obtained. Therefore, the fabricated membrane can be used as a portable molecular sensor that can be easily recycled.
Asunto(s)
Antibacterianos/análisis , Hidrogeles/química , Leche/química , Tetraciclina/análisis , Animales , Membranas Artificiales , Impresión Molecular , Estructura Molecular , Procesos FotoquímicosRESUMEN
Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) are attracting more and more attention for the neurodevelopment toxicity effects. We evaluated the concentrations of 15 individual OH-PBDEs and 3 bromophenol (BRP) congeners in 30 mother-newborn paired placenta, breast milk, fetal cord blood, and neonatal urine samples collected from South China. The geometric mean (GM) concentrations of ∑OH-PBDEs were 37.6, 61.3, and 76.8pgg(-1) ww in placenta, breast milk, and cord blood, respectively. The GM concentrations of ∑BRPs were 47.6, 119, and 30.2pgg(-1) ww in placenta, breast milk, and cord blood, respectively. The GM concentrations of ∑OH-PBDEs and ∑BRPs in neonatal urine were 72.0 and 79.8pgml(-1), respectively. Of the 15 OH-PBDE congeners analyzed, the three most frequently detected congeners were 2'-OH-BDE-68 (72.1%), 6-OH-BDE-47 (67.6%), and 2'-OH-BDE-28 (65.8%). The estimated daily intake (EDI) of OH-PBDEs for the breast-fed infants was 9.31±4.00ngkg(-1) bw day. The accumulation of OH-PBDEs in newborns was much lower than the estimated lowest observed-effect concentration (LOEC) of neurotoxicity. The present study provided the first systematic fundamental data that exposure to OH-PBDEs for newborn and their mothers in South China.
Asunto(s)
Contaminantes Ambientales/análisis , Retardadores de Llama/análisis , Éteres Difenilos Halogenados/análisis , Intercambio Materno-Fetal , Adulto , China , Monitoreo del Ambiente , Contaminantes Ambientales/sangre , Contaminantes Ambientales/orina , Femenino , Sangre Fetal/química , Éteres Difenilos Halogenados/sangre , Éteres Difenilos Halogenados/orina , Humanos , Hidroxilación , Recién Nacido , Exposición Materna , Leche Humana/química , Fenoles/análisis , Fenoles/sangre , Fenoles/orina , Placenta/química , Embarazo , Medición de Riesgo , Adulto JovenRESUMEN
A strand displacement reaction (SDR) system that runs solely on oligonucleotides has been developed for the amplification detection of adenosine triphosphate (ATP). It involves a target-induced SDR and an entropy-driven catalytic cycle of two SDRs with five oligonucleotides, denoted as substrate, fuel, catalyst, C-1, and C-2. Catalyst, released from the ATP aptamer-catalyst duplex by ATP molecule, catalyzes the SDRs to finally form the substrate-fuel duplex. All of the intermediates in the catalytic SDR processes have been identified by polyacrylamide gel electrophoresis (PAGE) analysis. The introduction of ATP into the SDR system will induce the ATP aptamer to form G-quadruplex conformation so as to release catalyst and trigger the SDR cycle. When the substrate and C-2 oligonucleotides were labeled with a carboxyfluorescein (FAM) fluorophore and a 4-([4-(dimethylamino)phenyl]azo)benzoic acid (DABCYL) quencher, this SDR catalytic system exhibited a "turn-on" response for ATP. The condition for detecting ATP, such as Mg²âº concentration, has been optimized to afford a detection limit of 20 nM. This work provides an enzyme-free biosensing strategy and has potential application in aptamer-based biosensing.
Asunto(s)
Adenosina Trifosfato/análisis , Técnicas Biosensibles/métodos , Catálisis , G-Cuádruplex , Límite de Detección , Magnesio/química , p-Dimetilaminoazobenceno/análogos & derivados , p-Dimetilaminoazobenceno/químicaRESUMEN
Small molecules are difficult to detect by the conventional quartz crystal microbalance with dissipation (QCM-D) technique directly because the changes in frequency resulting from the binding processes of small biomolecules are often small. In the current study, an aptamer-based gold nanoparticles (AuNPs)-enhanced sensing strategy for detection of small molecules was developed. The QCM crystal was first modified with a layer of thiolated linker DNA, which can be partly base-paired with the detection part containing the adenosine aptamer sequence. In the presence of adenosine, the aptamer bound with adenosine and folded to the complex structure, which precluded the reporter part carrying AuNPs to combine with the random coiled detection part. Therefore, the lower the concentration of adenosine, the more AuNPs combined to the crystal. The resulting aptasensor showed a linear response to the increase of the adenosine concentration in the range of 0-2 µM with a linear correlation of r=0.99148 and a detection limit of 65 nM. Moreover, the aptasensor exhibited several excellent characteristics such as high sensitivity, selectivity, good stability, and reproducibility.
Asunto(s)
Aptámeros de Nucleótidos/química , Técnicas Biosensibles/métodos , Oro/química , Nanopartículas del Metal/química , Tecnicas de Microbalanza del Cristal de Cuarzo/métodosRESUMEN
Polystyrene (PS) microspheres coated with ß-cyclodextrin (ß-CD) were fabricated via γ-ray-induced emulsion polymerization in a ternary system of styrene/ß-CD/water (St/ß-CD/water). The solid inclusion complex of St and ß-CD particles formed at the St droplets-water interface can stabilize the emulsion as the surfactant. TEM and XPS results showed that ß-CD remains on the surface of PS particles. The average size of the PS particles increases from 186 to 294 nm as the weight ratio of ß-CD to St rises from 5% to 12.5%. The water contact angle (CA) of PS latex film is lower than 90°, and reduces with the ß-CD content even to 36°. Thus, this work provides a new and one-pot strategy to surface hydrophilic modification on hydrophobic polymer particles with cyclodextrins through radiation emulsion polymerization.
Asunto(s)
Emulsiones/química , Rayos gamma , Poliestirenos/química , beta-Ciclodextrinas/química , Interacciones Hidrofóbicas e Hidrofílicas , Microesferas , Polimerizacion , Polimetil Metacrilato/química , Agua/químicaRESUMEN
A facultative anaerobic bacteria strain GS-4-08, isolated from an anaerobic sequence batch reactor for synthetic dye wastewater treatment, was investigated for azo-dye decolorization. This bacterium was identified as a member of Klebsiella oxytoca based on Gram staining, morphology characterization and 16S rRNA gene analysis. It exhibited a good capacity of simultaneous decolorization and hydrogen production in the presence of electron donor. The hydrogen production was less affected even at a high Methyl Orange (MO) concentration of 0.5 mM, indicating a superior tolerability of this strain to MO. This efficient bio-hydrogen production from electron donor can not only avoid bacterial inhibition due to accumulation of volatile fatty acids during MO decolorization, but also can recover considerable energy from dye wastewater.
Asunto(s)
Compuestos Azo/metabolismo , Colorantes/metabolismo , Hidrógeno/metabolismo , Klebsiella oxytoca/metabolismo , Eliminación de Residuos Líquidos/métodos , Microbiología del Agua , Anaerobiosis , Compuestos Azo/química , Biotecnología , Colorantes/química , Residuos Industriales , Klebsiella oxytoca/clasificación , Klebsiella oxytoca/genética , Klebsiella oxytoca/aislamiento & purificación , Oxidación-Reducción , Filogenia , Análisis de Secuencia de ADNRESUMEN
In this work, we investigated the anaerobic decolorization of methyl orange (MO), a typical azo dye, by Shewanella oneidensis MR-1, which can use various organic and inorganic substances as its electron acceptor in natural and engineered environments. S. oneidensis MR-1 was found to be able to obtain energy for growth through anaerobic respiration accompanied with dissimilatory azo-reduction of MO. Chemical analysis shows that MO reduction occurred via the cleavage of azo bond. Block of Mtr respiratory pathway, a transmembrane electron transport chain, resulted in a reduction of decolorization rate by 80%, compared to the wild type. Knockout of cymA resulted in a substantial loss of its azo-reduction ability, indicating that CymA is a key c-type cytochrome in the electron transfer chain to MO. Thus, the MtrA-MtrB-MtrC respiratory pathway is proposed to be mainly responsible for the anaerobic decolorization of azo dyes such as MO by S. oneidensis.
Asunto(s)
Compuestos Azo/metabolismo , Shewanella/metabolismo , Anaerobiosis , Metabolismo Energético , Eliminación de Gen , Redes y Vías Metabólicas/genética , Oxidación-Reducción , Shewanella/genética , Shewanella/crecimiento & desarrolloRESUMEN
Multiple microRNA (miRNA) logical assays have attracted wide attention recently, which can be applied to mimic and reveal cellular events at the molecular level. However, it remains challenging to develop labeling- and amplification-free approaches to perform logical functions with low levels of miRNA molecules. Herein, we proposed a strategy for miRNA logic operations using plasmid DNA-derived nanowires produced from a facile biosynthesis method. First, let-7d was chosen as the model target of the plasmid DNA-derived nanowire strategy, which showed good selectivity and a response sensitivity of as low as the femtomolar level. The operations of the miRNA logic gates proved the programmability of the constructed plasmid DNA-derived nanowire system for two inputs (let-7d and miR-21). Finally, three pairs of DNA nanowires were combined together to demonstrate the availability of this strategy in parallel multiple miRNAs assays. In this strategy, readout signals can be directly obtained from agarose gel without extra chemical labeling or amplification procedures. Considering the excellent performance of the logic gates with low levels of inputs, our plasmid DNA-derived nanowire strategy could provide a facile method to promote simultaneous multiple miRNA assays for the benefit of diagnosis and could be applied for the assembly of complex DNA nanostructures.
Asunto(s)
MicroARNs , Nanocables , Computadores Moleculares , ADN/química , ADN/genética , MicroARNs/genética , Plásmidos/genéticaRESUMEN
Adsorption and decolorization kinetics of methyl orange (MO) by anaerobic sludge in anaerobic sequencing batch reactors were investigated. The anaerobic sludge was found to have a saturated adsorption capacity of 36 ± 1 mg g MLSS(-1) to MO. UV/visible spectrophotometer and high-performance liquid chromatography analytical results indicated that the MO adsorption and decolorization occurred simultaneously in this system. This process at various substrate concentrations could be well simulated using a modified two-stage model with apparent pseudo first-order kinetics. Furthermore, a noncompetitive inhibition kinetic model was also developed to describe the MO decolorization process at high NaCl concentrations, and an inhibition constant of 3.67 g NaCl l(-1) was estimated. This study offers an insight into the adsorption and decolorization processes of azo dyes by anaerobic sludge and provides a better understanding of the anaerobic dye decolorization mechanisms.
Asunto(s)
Compuestos Azo/química , Compuestos Azo/metabolismo , Bacterias/metabolismo , Colorantes/química , Colorantes/metabolismo , Aguas del Alcantarillado/microbiología , Adsorción , Anaerobiosis , Bacterias/química , Biodegradación Ambiental , Cinética , Aguas del Alcantarillado/químicaRESUMEN
A model azo dye, methyl orange (MO), was reduced through in situ utilization of the electrons derived from the anaerobic conversion of organics in a microbial fuel cell (MFC). The MO reduction process could be described by a pseudo first-order kinetic model with a rate constant of 1.29 day(-1). Electrochemical impedance spectroscopic analysis shows that the cathode had a high polarization resistance, which could decrease the reaction rate and limit the electron transfer. To improve the MO reduction efficiency, the cathode was modified with redox mediators to enhance the electron transfer. After modification with thionine, the polarization resistance significantly decreased by over 50%. As a consequence, the MO decolorization rate increased by over 20%, and the power density was enhanced by over three times. Compared with thionine, anthraquinone-2, 6-disulfonate modified cathode has less positive effect on the MFC performance. These results indicate that the electrode modification with thionine is a useful approach to accelerate the electrochemical reactions. This work provides useful information about the key factors limiting the azo dye reduction in the MFC and how to improve such a process.
Asunto(s)
Compuestos Azo/metabolismo , Bacterias/metabolismo , Fuentes de Energía Bioeléctrica/microbiología , Electrodos/microbiología , Compuestos Azo/química , Bacterias/química , Biodegradación Ambiental , Colorantes/química , Colorantes/metabolismo , Impedancia Eléctrica , Cinética , Oxidación-ReducciónRESUMEN
The bis(diphenylphosphino)methane (dppm)-bridged dinuclear cycloplatinated complex {[Pt(L)](2)(mu-dppm)}(2+) (Pt(2)dppm; HL: 2-phenyl-6-(1H-pyrazol-3-yl)-pyridine) demonstrates interesting reversible "pivot-hinge"-like intramolecular motions in response to the protonation/deprotonation of L. In its protonated "closed" configuration, the two platinum(II) centers are held in position by intramolecular d(8)-d(8) Pt-Pt interaction. In its deprotonated "open" configuration, such Pt-Pt interaction is cleaved. To further understand the mechanism behind this hingelike motion, an analogous dinuclear cycloplatinated complex, {[Pt(L)](2)(mu-dchpm)}(2+) (Pt(2)dchpm) with bis(dicyclohexylphosphino)methane (dchpm) as the bridging ligand, was synthesized. From its protonation/deprotonation responses, it was revealed that aromatic pi-pi interactions between the phenyl moieties of the mu-dppm and the deprotonated pyrazolyl rings of L was essential to the reversible cleavage of the intramolecular Pt-Pt interaction in Pt(2)dppm. In the case of Pt(2)dchpm, spectroscopic and spectrofluorometric titrations as well as X-ray crystallography indicated that the distance between the two platinum(II) centers shrank upon deprotonation, thus causing a redshift in its room-temperature triplet metal-metal-to-ligand charge-transfer emission from 614 to 625 nm. Ab initio calculations revealed the presence of intramolecular hydrogen bonding between the deprotonated and negatively charged 1-pyrazolyl-N moiety and the methylene CH and phenyl C-H of the mu-dppm. The "open" configuration of the deprotonated Pt(2)dppm was estimated to be 19 kcal mol(-1) more stable than its alternative "closed" configuration. On the other hand, the open configuration of the deprotonated Pt(2)dchpm was 6 kcal mol(-1) less stable than its alternative closed configuration.
RESUMEN
An amphiphilic, water-soluble cyclometalated Pt(II) complex with two-photon emission properties has been developed as a molecular marker specific for in vitro plasma membrane staining.
Asunto(s)
Membrana Celular/metabolismo , Compuestos Organoplatinos/química , Compuestos Organoplatinos/metabolismo , Fotones , Agua/química , Supervivencia Celular , Cloro/química , Células HeLa , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Ligandos , Solubilidad , Espectrofotometría Ultravioleta , Coloración y EtiquetadoRESUMEN
The cyclometalated platinum(II) complex [Pt(L)Cl], where HL is a new cyclometalating ligand 2-phenyl-6-(1H-pyrazol-3-yl)pyridine containing C(phenyl), N(pyridyl), and N(pyrazolyl) donor moieties, was found to possess two-photon-induced luminescent properties. The two-photon-absorption cross section of the complex in N,N-dimethylformamide at room temperature was measured to be 20.8 GM. Upon two-photon excitation at 730 nm from a Ti:sapphire laser, bright-green emission was observed. Besides its two-photon-induced luminescent properties, [Pt(L)Cl] was able to be rapidly accumulated in live HeLa and NIH3T3 cells. The two-photon-induced luminescence of the complex was retained after live cell internalization and can be observed by two-photon confocal microscopy. Its bioaccumulation properties enabled time-lapse imaging of the internalization process of the dye into living cells. Cytotoxicity of [Pt(L)Cl] to both tested cell lines was low, according to MTT assays, even at loadings as high as 20 times the dose concentration for imaging for 6 h.
Asunto(s)
Fotones , Compuestos de Platino/química , Animales , Línea Celular , Supervivencia Celular/efectos de los fármacos , Ciclización , Humanos , Ratones , Estructura Molecular , Fotoquímica , Compuestos de Platino/toxicidad , EspectrofotometríaRESUMEN
The kinetics of the photoinduced degradation and transformation of the antifouling booster biocide, Irgarol-1051, in natural coastal seawater was studied. The measured first-order rate constant for the degradation of Irgarol-1051 was 4.02+/-0.1 x 10(-4)h(-1), while the rate constant for the formation of 2-methylthio-4-tert-butylamino-6-amino-s-triazine (M1), the most dominant degradation product of Irgarol-1051, was 4.6+/-0.1 x 10(-5)h(-1). This considerably slower rate suggested that the transformation of Irgarol-1051 to M1 may not be the predominant pathway of the photodegradation process. During the photodegradation study, a new s-triazine species was observed in the degradation mixtures which, together with M1, appeared immediately upon photolysis and continued to accumulate in the degradation mixture throughout the entire study duration. This is in contrast to the behaviour of the recently identified degradation product of Irgarol-1051, 3-[4-tert-butylamino-6-methylthiol-s-triazin-2-ylamino]- propionaldehyde (M2), which was only detected in the degradation mixture after a long induction period. High-resolution tandem mass spectrometric analysis hinted that the new degradation product (M4) may possess a terminal alcohol and is likely to be an N-allylic alcohol derivative of M1. This suggests that M4 may, indeed, be a precursor of M2 via redox transformation at its N-allylic alcohol functionality.
Asunto(s)
Fotólisis , Agua de Mar/química , Triazinas/química , Triazinas/metabolismo , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/metabolismo , CinéticaRESUMEN
A strategy to construct multivariate biomarkers for exposure to algal neurotoxins via correlating changes to the profiles of a series of neurotransmitters and their metabolites in the central nervous system (CNS) of exposed test organism is reported. 3-Month-old marine medaka (Oryzais melastigma) were exposed to waterborne brevetoxin PbTx-1 at two sub-lethal dose levels (0.5 and 2.5⯵g-PbTx-1â¯L-1) for a duration of 12â¯h before quantification of 43 selected neurotransmitters and metabolites in their CNS were measured via dansyl chloride derivatization and LC-MS/MS determination. The profiling data were analyzed by multivariate statistical analyses, including principle component analysis (PCA), projection on latent structure-discriminate analysis (PLS-DA) and orthogonal projection on latent structure-discriminate analysis (OPLS-DA). Neurotransmitters and metabolites related to activation of voltage-gated sodium channels (VGSCs), N-methyl-D-aspartic acid receptors (NMDARs) and cholinergic neurotransmission were found to contribute significantly to class separation in the corresponding OPLS-DA models. Those models obtained from different exposure dosages were correlated by the Shared and Unique Structures Plot (SUS-plot) to identify appropriate variables for the construction of exposure biomarkers in the form of multivariate predictive scores. The established biomarkers for male and female medaka fish were able to predict acute sub-lethal exposure to PbTx-1 with good sensitivity and specificity (male fish: sensitivity 94.7%, specificity 80.0%; female fish: sensitivity 91.4%, specificity 83.3%). Neurotransmitter profiles in the CNS of medaka fish that should have recovered from exposure to PbTx-1 have also been determined to reveal long-term impacts to the CNS of the affected organism even after the exposure has been interrupted.