Potentiometric sensor for atrazine based on a molecular imprinted membrane

A molecular imprinted polymer (MIP) membrane for atrazine, not containing macropores, was synthesized and implemented in a potentiometric sensor. It is expected to work like a solid ISE (where the specific carrier are the imprinted sites) the specific carrier being the imprinted site. The active ion is the protonated atrazine, positively charged. To form this species the determination is carried out in acidic solution at pH lower than 1.8, in which atrazine is prevalently monoprotonated. At these conditions the membrane potential increases with atrazine concentration over a wide concentration range (3 x 10(-5) to 1 x 10(-3)M). The slope of the function E versus logc is about 25 mV/decade, showing that the atrazine form sorbed on MIP is the biprotonated one. The detection limit is determined by the relatively high concentration of atrazine released by the membrane in the sample solution at the considered conditions. It seems to be independent of the atrazine concentration in the internal solution of the sensor, but it depends on the acidity of the solution. The response time is less than 10s and the sensor can be used for more than 2 months without any divergence.     

Atrazine degradation by bioaugmented sediment from constructed wetlands

The potential to establish pesticide biodegradation in constructed wetland sediment was investigated. Under microcosm conditions, bioaugmentation of sediment with small quantities of an atrazine spill-site soil (1:100 w/w) resulted in the mineralization of 25-30% of 14C ethyl atrazine (1-10 microg g(-1) sediment) as 14CO2 under both unsaturated and water-saturated conditions; atrazine and its common metabolites were almost undetectable after 30 days incubation. By comparison, unbioaugmented sediment supplemented with organic amendments (cellulose or cattail leaves) mineralized only 2-3% of 14C ethyl atrazine, and extractable atrazine and its common metabolites comprised approximately 70% of the original application. The population density of atrazine-degrading microorganisms in unbioaugmented sediment was increased from approximately 10(2)/g to 10(4)/g by bioaugmentation (1:100 w/w), and increased by another 60-fold (6.0x10(5) g(-1)) after incubation with 10 microg g(-1) of atrazine. A high population of atrazine degraders (approximately 10(6) g(-1)) and enhanced rates of atrazine mineralization also developed in bioaugmented sediment after incubation in flooded mesocosms planted with cattails (Typha latifolia) and supplemented with atrazine (3.2 mg l(-1), 1 microg g(-1) sediment). In the absence of atrazine, neither the population of atrazine degraders, nor the atrazine mineralizing potential of bioaugmented sediment increased, regardless of the presence or absence of cattails. Bioaugmentation might be a simple method to promote pesticide degradation in nursery run-off channeled through constructed wetlands, if persistence of degraders in the absence of pesticide is not a serious constraint.     

Effects of atrazine on osmoregulation in the Chinese mitten crab,Eriocheir sinensis

This study integrates results from acute contamination with atrazine of isolated perfused gills, and from in vivo chronic contamination of euryhaline Chinese mitten crabs, Eriocheir sinensis, acclimated to freshwater. Atrazine 1 mg/l in contact with the basolateral membrane (IN) increases the transepithelial potential difference (TEP) from -20.8 +/- 4.9 to -29.7 +/- 3.8 mV in isolated perfused posterior gills (P < 0.01). This effect is only partially explained by a modification of Na(+) and Cl(-) active influxes. No TEP modification is detected when atrazine is added (OUT) indicating that molecular mechanisms located on the basolateral membrane are likely to be the only ones affected. Another explanation would be that cuticular barrier prevents atrazine penetration into the gill. Haemolymph osmolarity, Na(+) and Cl(-) concentrations of crabs living in freshwater contaminated with atrazine 1 mg/l during 14 days are not significantly modified. We conclude that although atrazine can disturb osmoregulatory mechanisms of isolated gills, this pollutant would be of minor importance in affecting osmoregulatory capacities of the Chinese mitten crab in natural conditions.     

Response of multiple herbicide resistant strain of diazotrophic cyanobacterium, Anabaena variabilis, exposed to atrazine and DCMU

Effect of two photosynthetic inhibitor herbicides, atrazine (both purified and formulated) and [3-(3,4-dichlorophenyl)-1,1-dimethyl urea] (DCMU), on the growth, macromolecular contents, heterocyst frequency, photosynthetic O2 evolution and dark O2 uptake of wild type and multiple herbicide resistant (MHR) strain of diazotrophic cyanobacterium A. variabilis was studied. Cyanobacterial strains showed gradual inhibition in growth with increasing dosage of herbicides. Both wild type and MHR strain tolerated < 6.0 mg L(-1) of atrazine (purified), < 2.0 mg L(-1) of atrazine (formulated) and < 0.4 mg L(-1) of DCMU indicating similar level of herbicide tolerance. Atrazine (pure) (8.0 mg L(-1)) and 4.0 mg L(-1) of atrazine (formulated) were growth inhibitory concentrations (lethal) for both wild type and MHR strain indicating formulated atrazine was more toxic than the purified form. Comparatively lower concentrations of DCMU were found to be lethal for wild type and MHR strain, respectively. Thus, between the two herbicides tested DCMU was more growth toxic than atrazine. At sublethal dosages of herbicides, photosynthetic O2 evolution showed highest inhibition followed by chlorophyll a, phycobhiliproteins and heterocyst differentiation as compared to carotenoid, protein and respiratory O2 uptake.     

Stereoselective histidine sensor based on molecularly imprinted sol-gel films

A piezoelectric sensor coated with a thin molecularly imprinted sol-gel film has been developed for the determination of L-histidine in the liquid phase. Without preprotection, L-histidine was imprinted directly into silica sol-gel films that consisted of a hybrid mixture of functionalized organosilicon precursors (phenyltrimethoxysilane and methyltrimethoxysolane). The viscoelasticity of the film in the air and in buffer solution has been studied by the piezoelectric quartz crystal impedance technique. The binding of L-histidine to the imprinted film in the liquid phase was investigated by the piezoelectric microgravimetry and electrochemical impedance technique. Scatchard analysis showed that the maximum binding site (Qmax) of the L-histidine imprinted sol-gel film is about 23.7 micromol/g. A linear range from 5.0x10(-8) to 1.0x10(-4) M for a detection of L-histidine has been observed with a detection limit of 2.5x10(-8) M for S/N=3. The proposed imprinted sol-gel sensor exhibits good stability, high specificity, and excellent stereoselectivity.     

Immunomodulation of human natural killer cell cytotoxic function by triazine and carbamate pesticides

Triazine (atrazine) and carbamates (maneb, metiram, and ziram) are used as pesticides on a variety of crops around the world. To our knowledge, there have been no studies dealing with the effects of these compounds on human natural killer (NK) cells cytotoxic function. NK cells play a central role in immune defense against tumor development and viral infections. Thus, any agent that interferes with the ability of NK cells to lyse their targets could increase the risk of tumor incidence and/or viral infections. In this study, we examined the effects of atrazine, maneb, metiram, zineb, and ziram on the ability of human NK cells to lyse tumor cells. The compounds were tested in both purified NK cells as well as a cell preparation that contained both T and NK lymphocytes (T/NK cells). Lymphocytes were exposed to the compounds for periods of time ranging from 1 h to 6 days. Exposure of highly purified NK cells to 10 microM atrazine, maneb, or metiram inhibited K562 tumor cell lysis by 63+/-25, 95+/-4, and 50+/-6%, respectively, after a 24 h exposure and by 83+/-21, 70+/-39, and 48+/-41% after a 6-day exposure. Exposure to 2.5 microM ziram for 24 h caused a 99+/-2% decrease in lytic function and at 1 microM for 6 days caused a 96+/-4% decrease. However, when T/NK cells were exposed to atrazine, maneb, or metiram for 24 h only 10 microM atrazine and maneb caused a significant decreases in lytic function (61+/-13 and 38+/-18%) and after 6 days only atrazine was inhibitory (54+/-12%). A 24-h exposure to 2.5-microM ziram caused a 41+/-51% decrease in function, but a 6-day exposure to 1 microM ziram caused no inhibition of lytic function. The results provide evidence of relative toxic potential for the five compounds and the immunomodulatory effects on both T and NK lymphocyte function.     

Binding site of novel 2-benzylamino-4-methyl-6-trifluoromethyl-1,3,5- triazine herbicides in the D1 protein of Photosystem II

A series of replacement experiments of [¹⁴C]-triazines, [¹⁴C]-atrazine and [7-¹⁴C]-2-benzylamino-4-methyl-6-trifluoromethyl-1,3,5-triazine, bound to thylakoids isolated from wild-type and atrazine-resistant Chenopodium album (lambsquarters) were conducted. Replacement experiments of [¹⁴C]-triazines bound to wild-type Chenopodium thylakoids with non-labeled atrazine and 2-benzylamino-4-methyl-6-trifluoromethyl-1,3,5-triazine were carried out, to elucidate whether benzylamino-1,3,5-triazines use the same binding niche as atrazine. [¹⁴C]-Atrazine and [7-¹⁴C]-2-benzylamino-4-methyl-6-trifluoromethyl-1,3,5-triazine bound to wild-type thylakoids were replaced by non-labeled 2-benzylamino-4-methyl-6-trifluoromethyl-1,3,5-triazine and non-labeled atrazine, respectively. The above two replacements showed mutual competition. To clarify further whether benzylamino-1,3,5-triazines bind at the D1-protein to amino acid residue(s) different from atrazine or not, experiments to replace [7-¹⁴C]-2-benzylamino-4-methyl-6-trifluoromethyl-1,3,5-triazines bound to atrazine-resistant Chenopodium thylakoids by non-labeled atrazine, 2-(4-bromobenzylamino)-4-methyl-6-trifluoromethyl-1,3,5-triazine, DCMU and DNOC were carried out. Although the bound [7-¹⁴C]-2-benzylamino-4-methyl-6-trifluoromethyl-1,3,5-triazine was difficult to be replaced even with high concentrations of atrazine, [¹⁴C]-labeled 1,3,5-triazine was competitively replaced by non-labeled 2-(4-bromobenzylamino)-4-methyl-6-trifluoromethyl-1,3,5-triazine, DCMU or DNOC. Thus, 2-benzylamino-4-methyl-6-trifluoromethyl-1,3,5-triazine herbicides are considered to bind to the same niche at the D1 protein as atrazine, but use amino acid residue(s) different from those involved with atrazine binding. This revised version was published online in August 2006 with corrections to the Cover Date.     

Degradation of the herbicide atrazine by the soil mycelial fungus INBI 2-26(-)--a producer of cellobiose dehydrogenase

Nonsporulating mycelial fungi producing cellobiose dehydrogenase (CDH) and isolated from soils of South Vietnam with high residual content of dioxins are capable of growing on a solid medium in the presence of high atrazine concentrations (to 500 mg/l). At 20 and 50 mg/l atrazine, the area of fungal colonies was 1.5-1.2-fold larger, respectively, compared with control colonies of the same age, whereas development of the colonies at 500 mg/l atrazine was delayed by 5 days, compared with controls grown in the absence of atrazine. Surface cultivation of the fungus on a minimal medium with glucose as a sole source of carbon and energy decreased the initial concentration of atrazine (20 mg/l) 50 times in 40 days; in addition, no pronounced sorption of atrazine by mycelium was detected. This was paralleled by accumulation in the culture medium of extracellular CDH; atrazine increased the synthesis of this enzyme two- to threefold. Accumulation of beta-glucosidase (a mycelium-associated enzyme) and cellulases preceded the formation of CDH.     

Cloning, characterization, and expression of a gene region from Pseudomonas sp. strain ADP involved in the dechlorination of atrazine.

We previously identified a Pseudomonas sp. strain, ADP, which rapidly metabolized atrazine in liquid culture, agar plates, and soils (R. T. Mandelbaum, D. L. Allan, L. P. Wackett, Appl. Environ. Microbiol. 61:1451-1457, 1995). In this study, we report the cloning and partial characterization of a gene region from Pseudomonas sp. strain ADP that encodes atrazine degradation activity. A 22-kb EcoRI genomic DNA fragment, designated pMD1, was shown to encode atrazine dechlorination activity in Escherichia coli DH5 alpha. Atrazine degradation was demonstrated by a zone-clearing assay on agar medium containing crystalline atrazine and by chromatographic methods. A gene conferring the atrazine-clearing phenotype was subsequently subcloned as a 1.9-kb AvaI fragment in pACYC184, designated pMD4, and was expressed in E. coli. This result and random Tn5 mutagenesis established that the 1.9-kb AvaI fragment was essential for atrazine dechlorination. High-pressure liquid and thin-layer chromatographic analyses were used to rigorously establish that E. coli containing pMD4 degraded atrazine and accumulated hydroxyatrazine. Hydroxyatrazine was detected only transiently in E. coli containing pMD1. This is consistent with the idea that hydroxyatrazine is the first metabolite in atrazine degradation by Pseudomonas sp. strain ADP. A 0.6-kb ApaI-PstI fragment from pMD4, containing the putative atrazine chlorohydrolase gene, hybridized to DNA from atrazine-degrading bacteria isolated in Switzerland and Louisiana.(ABSTRACT TRUNCATED AT 250 WORDS)     

Protective effects of vitamin E against atrazine-induced genotoxicity in rats

Atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) is one of the most commonly used herbicides to control grasses and weeds. The widespread contamination and persistence of atrazine residues in the environment has resulted in human exposure. Vitamin E is a primary antioxidant that plays an important role in protecting cells against toxicity by inactivating free radicals generated following pesticides exposure. The present study was undertaken to investigate the protective effect of vitamin E against atrazine-induced genotoxicity. Three different methods: gel electrophoresis, comet assay and micronucleus test were used to assess the atrazine-induced genotoxicity and to evaluate the protective effects of vitamin E. Atrazine was administered to male rats at a dose of 300 mg/kg body weight for a period of 7, 14 and 21 days. There was a significant increase (P<0.001) in tail length of comets from blood and liver cells treated with atrazine as compared to controls. Co-administration of vitamin E (100 mg/kg body weight) along with atrazine resulted in decrease in tail length of comets as compared to the group treated with atrazine alone. Micronucleus assay revealed a significant increase (P<0.001) in the frequency of micronucleated cells (MNCs) following atrazine administration. In the animals administrated vitamin E along with atrazine there was a significant decrease in percentage of micronuclei as compared to atrazine treated rats. The increase in frequency of micronuclei in liver cells and tail length of comets confirm genotoxicity induced by atrazine in blood and liver cells. In addition, the findings clearly demonstrate protective effect of vitamin E in attenuating atrazine-induced DNA damage.     

An impedimetric immunosensor based on interdigitated microelectrodes (IDmicroE) for the determination of atrazine residues in food samples

A novel impedimetric immunosensor for atrazine detection has been developed. The immunosensor is based on an array of interdigitated micro-electrodes (IDmicroE) and immunoreagents specifically developed to detect this pesticide. Immunochemical determination of atrazine is possible without the use of any label. An atrazine-haptenized protein was covalently immobilized on the surface of the interdigitated mu-electrodes area (interdigits space) previously activated with (3-glycidoxypropyl)trimethoxysilane. Before, the gold electrodes were blocked using N-acetylcysteamine to prevent non-specific adsorptions. All biofunctionalization steps were characterized by chemical affinity methods and impedance spectroscopy. Immunosensors measures are made by exposing the sensor to solutions containing a mixture of the analyte and the specific antibody. With this configuration, the immunosensor detects atrazine with a limit of detection of 0.04 microg L(-1) without the use of any label. The potential of the immunosensor to analyze pesticide residues in complex sample matrices, such as red wine, has been evaluated. The results shown that after solid-phase extraction atrazine can be determined in this type of sample with a limit of detection of 0.19 microg L(-1), far below the Maximum Residue Level (MRL) established by EC for residues of this herbicide in wine.     

Herbicides for Establishing Switchgrass in the Central and Northern Great Plains

Weed interference limits switchgrass (Panicum virgatum L.) establishment from seed. Our objectives were to determine the effect of selected post-plant, preemergence herbicides on stand establishment and subsequent biomass yields of adapted upland switchgrass cultivars grown in three environments in the Central and Northern Great Plains. A separate experiment was conducted in eastern Nebraska to determine if there were any differences among switchgrass ecotypes for herbicide tolerance to the optimal herbicide combination. Herbicides applied immediately after planting were different concentrations of atrazine [Aatrex 4L®; 6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine], quinclorac (Paramount®; 3,7-Dichloro-8-quinolinecarboxylic acid), atrazine+quinclorac, imazapic {Plateau®; 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid}, and quinclorac+imazapic. Herbicide efficacy was determined by measuring stand frequency of occurrence and biomass yield the year after establishment. The application of quinclorac plus atrazine resulted in acceptable stands and high biomass yields. Imazapic often reduced switchgrass stands in comparison to the nontreated control and is not recommended for switchgrass establishment. In the multi-state trials, the herbicide by cultivar interaction was not significant for stands or biomass yields, indicating that the effects of herbicides on switchgrass stands and biomass yields were consistent over the upland cultivars used in the trials. No differences were detected among switchgrass lowland and upland ecotypes for tolerance to atrazine and quinclorac. Quinclorac, which provides effective control of grassy weeds, and herbicides such as atrazine which provide good broadleaf weed control are an excellent herbicide combination for establishing switchgrass for biomass production in the Great Plains and the Midwest.     

Studies on the light-induced loss of the D1 protein in photosystem-II membrane fragments

PS II membrane fragments produced from higher plant thylakoids by Triton X-100 treatment exhibit strong photoinhibition and concomitant fast degradation of the D1 protein. Involvement of (molecular) oxygen is necessary for degradation of the D1 protein.The herbicides atrazine and diuron, but not ioxynil, partly protect the D1 protein against degradation. Binding of atrazine to the D1 protein is necessary to protect the D1 polypeptide, as shown with PS II membrane fragments from an atrazine-resistant biotype of Chenopodium album which are protected by diuron not by atrazine.Abbreviations atrazine 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine - Chl chlorophyll, diuron - (DCMU) 3-(3,4-dichlorophenyl)-1,1-dimethylurea - DMBQ 2,5-dimethyl-p-benzoquinone - DCIP 2,6-dichlorophenol indophenol - DPC diphenylcarbazide - ioxynil 4-cyano-2,6-diiodophenol - k_b binding constant - Mes 4-morpholinoethanesulfonic acid - P-680 reaction-center chlorophyll a of photosystem-II - PAGE polyacrylamide gel electrophoresis - PS II photosystem-II - Q_A and Q_B primary and secondary quinone electron acceptors - Z electron donor to the photosystem-II reaction center - SDS sodium dodecylsulfate - Tricine N-2-hydroxy-1,1-bis(hydroxymethyl)ethylglycine     

Consumption of the triazine herbicide atrazine by laccase and laccase-free variants of the soil fungus Mycelia sterilia INBI-2-26

Asporogenic fungus Mycelia sterilia INBI 2-26 isolated from tropical soils with high residual dioxin content (as a result of Agent Orange defoliant treatment during the Vietnamese-American war) and capable of atrazine decomposition was treated to obtain protoplasts. This technique resulted in isolation of laccase-positive and laccase-negative clones. Atrazine consumption by liquid surface cultures of Mycelia sterilia INBI 2-26 was monitored by using enzyme immune assay and reversed phase HPLC. Atrazine (20 micrograms/l) stimulated fungal growth. Laccase-positive clone consumed up to 80% of atrazine within four weeks. However, no correlation of atrazine consumption and laccase activity in the culture medium was observed. Moreover, the laccase-negative clone was also capable of consuming at least 60-70% of atrazine within three weeks. Surprisingly, in the corresponding control set (cultivation of laccase-negative clone without atrazine) an unidentified metabolite having a retention time and UV-spectrum similar to those of atrazine was also found. It was concluded that the presence of laccase was not a crucial factor in atrazine consumption by this fungus.     

Immunoenzyme analysis of decomposition of herbicides by soil and wood-rot fungi

The effect of herbicide atrazine was studied on the growth and development of a number of soil and wood decay fungi: white-rot basidiomycetes (Cerrena maxima, Coriolopsis fulvocenerea, and Coriolus hirsutus), thermophilic micromycetes from self-heating grass composts (cellulolytic fungus Penicillium sp. 13 and noncellulolytic ones Humicola lanuginosa spp. 5 and 12), and mesophilic phenol oxidase-producing micromycete Mycelia sterilia INBI 2-26. Detection of atrazine in liquid fungal cultures was performed by using enzyme immunoassay technique. Both stimulation (Humicola lanuginosa 5) and suppression (Humicola lanuginosa 12 and Penicillium sp. 13) of fungal growth with atrazine were observed on solid agar media. Hyphomycete Mycelia sterilia INBI 2-26 was almost insensitive to the presence of atrazine. Neither of thermophilic strains was capable of atrazine consumption in three-week cultivation. In contrast with that, active laccase producers Cerrena maxima, Coriolopsis fulvocenerea, and Coriolus hirsutus consumed up to 50% atrazine in 5-day cultivation in the presence of the xenobiotic and at least 80-90% in 40 days. Mycelia sterilia INBI 2-26, which also forms extracellular laccase, also consumed up to 70% atrazine in 17 days. The degree of atrazine consumption depended on the term of its addition to the fungal culture medium.     

Atrazine-induced alterations in rat erythrocyte membranes: ameliorating effect of vitamin E

Erythrocytes are a convenient model to understand oxidative damage to the membranes induced by various xenobiotics. The objective of the present study was to investigate the propensity of atrazine to induce oxidative stress and its possible attenuation by vitamin E. Experimental animals were orally administered atrazine (300 mg kg(-1) body weight, daily) and vitamin E (100 mg kg(-1) body weight, daily) for a period of 7, 14, and 21 days. Erythrocyte membranes were prepared and analyzed for acetylcholinesterase (AChE) activity, lipid peroxidation (LPO), and lipid composition. Susceptibility of erythrocytes to atrazine exposure was further investigated in terms of morphological alterations by scanning electron microscopy (SEM). Results indicate that atrazine exposure caused a significant inhibition of AChE activity and induction of oxidative stress in terms of increased malondialdehyde (MDA) levels. Atrazine treatment significantly decreased total lipid, cholesterol, and phospholipid content of erythrocyte membranes. SEM revealed varying degrees of distortion depending on duration of atrazine exposure. However, administration of vitamin E ameliorated the oxidative stress and changes in the erythrocyte membranes induced by atrazine.     

Modification of Herbicide Binding to Photosystem II in Two Biotypes of Senecio vulgaris L

The present study compares the binding and inhibitory activity of two photosystem II inhibitors: 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron [DCMU]) and 2-chloro-4-(ethylamine)-6-(isopropyl amine)-S-triazene (atrazine). Chloroplasts isolated from naturally occurring triazine-susceptible and triazine-resistant biotypes of common groundsel (Senecio vulgaris L.) showed the following characteristics. (a) Diuron strongly inhibited photosynthetic electron transport from H₂O to 2,6-dichlorophenolindophenol in both biotypes. Strong inhibition by atrazine was observed only with the susceptible chloroplasts. (b) Hill plots of electron transport inhibition data indicate a noncooperative binding of one inhibitor molecule at the site of action for both diuron and atrazine. (c) Susceptible chloroplasts show a strong diuron and atrazine binding (¹⁴C-radiolabel assays) with binding constants (K) of 1.4 × 10⁻⁸ molar and 4 × 10⁻⁸ molar, respectively. In the resistant chloroplasts the diuron binding was slightly decreased (K = 5 × 10⁻⁸ molar), whereas no specific atrazine binding was detected. (d) In susceptible chloroplasts, competitive binding between radioactively labeled diuron and non-labeled atrazine was observed. This competition was absent in the resistant chloroplasts.     

Rapid and specific detection of herbicides using a self-assembled photosynthetic reaction center from purple bacterium on an SPR chip

In this study, a direct detection system for herbicides inhibiting photosynthetic electron transfer was developed using the photosynthetic reaction center (RC) from the purple bacterium, Rhodobacter sphaeroides, and surface plasmon resonance (SPR) apparatus. The heavy-subunit-histidine-tagged RCs (HHisRCs) were immobilized on an SPR sensor chip via nickel chelation chemistry as a binder for one of the triazine herbicides, atrazine. Immediately after injection of atrazine solution on the HHisRCs-immobilized chip, the SPR responses increased and reached plateaus within 1 min. The SPR signals were proportional to the sample concentrations of atrazine in the range 1-100 microg/ml. To evaluate the binding specificity to atrazine, chlorinated aromatic herbicides, DCMU and MCPP, were investigated using the HHisRCs-immobilized chip. An RC inhibitor, DCMU, could also be detected with a higher detection limit of 20 microg/ml than atrazine (1 microg/ml). MCPP showed no signals because its inhibition mechanism against plants is different from that of atrazine and DCMU. These results indicated that the sensor chip immobilized RCs could be used for the specific detection of photosynthetic inhibitors.