Abstract  A highly sensitive acetylcholinesterase biosensor was developed for detection of carbamate drugs based on TTF-TCNQ-ionic liquid gel thiocholine sensor. The TTF-TCNQ-ionic/ionic liquid gel was characterized by FT-IR and scanning electron microscopy. The electrocatalytic behavior of TTF-TCNQ-ionic liquid gels toward oxidation of thiocholine was thoroughly investigated. 1-Ethyl-3-methylimidazolium tetracyanoborate gel based sensor allowed amperometric detection of thiocholine at +400 mV vs. Ag/AgCl with a high sensitivity of 55.9±1.2 μA mM(-1)cm(-2) and a low detection limit equal to 7.6 μM. The catalytic rate constant and diffusion constant of thiocholine were estimated from chronoamperometric data. The proposed biosensor based on AChE immobilized in sol-gel matrix was used for the detection of two carbamate therapeutic drugs. Very low detection limits of 26 pM eserine and 0.3 nM neostigmine were achieved. The analysis of spiked tap water proved the biosensor capability to be used as a screening method for detection of carbamate drugs in wastewaters.

Abstract  The growth of mass populations of toxin-producing cyanobacteria is a serious concern for the ecological status of inland waterbodies and for human and animal health. In this study we examined the performance of four semi-analytical algorithms for the retrieval of chlorophyll a (Chl a) and phycocyanin (C-PC) from data acquired by the Compact Airborne Spectrographic Imager-2 (CASI-2) and the Airborne Imaging Spectrometer for Applications (AISA) Eagle sensor. The retrieval accuracies of the semi-analytical models were compared to those returned by optimally calibrated empirical band-ratio algorithms. The best-performing algorithm for the retrieval of Chl a was an empirical band-ratio model based on a quadratic function of the ratio of reflectance at 710 and 670 nm (R(2) = 0.832; RMSE =29.8%). However, this model only provided a marginally better retrieval than the best semi-analytical algorithm. The best-performing model for the retrieval of C-PC was a semi-analytical nested band-ratio model (R(2) = 0.984; RMSE = 3.98 mg m(-3)). The concentrations of C-PC retrieved using the semi-analytical model were correlated with cyanobacterial cell numbers (R(2) = 0.380) and the particulate and total (particulate plus dissolved) pools of microcystins (R(2) = 0.858 and 0.896 respectively). Importantly, both the empirical and semi-analytical algorithms were able to retrieve the concentration of C-PC at cyanobacterial cell concentrations below current warning thresholds for cyanobacteria in waterbodies. This demonstrates the potential of remote sensing to contribute to early-warning detection and monitoring of cyanobacterial blooms for human health protection at regional and global scales. (C) 2010 Elsevier Inc. All rights reserved.

Abstract  Nitrogen (N) supply in pulses was simulated by exposing Alexandrium tamarense which was acclimatized at low N concentration (6 muM-N) to sudden increase in concentrations of nitrate, ammonium and urea, and the variability in toxicity due to nutrient status of A. tamarense was examined. The toxin composition did not vary dramatically among the three N sources, however, ammonium induced the highest concentration of intracellular toxin, followed by urea and then nitrate. Therefore, populations utilizing high ammonium concentration Could be more toxic than those growing on nitrate or urea. The toxin content was dependent on the cellular N status of nitrate grown cells only, suggesting that the competition for N in toxin production with other metabolic pathways such as growth may be different among N Sources. The relationship between toxin and nutrient status is a complex interaction and it involves the redistribution of cellular N within the cells. Understanding the toxin dynamics of natural Populations in relation to nutrient is essential for the mitigation of harmful dinoflagellates in a given coastal ecosystem. (C) 2004 Elsevier Ltd. All rights reserved.

Abstract  The oxidation of microcystin-LR (MC-LR) present in natural waters with chlorine and potassium permanganate under real drinking water treatment conditions has been investigated in the present work. The natural waters were spiked with MC-LR, using the typical concentration of 5 mu gL(-1) found in natural waters. The influence of some operational parameters such as the initial oxidant concentration, pH and temperature and of some drinking water quality parameters such as the NOM and ammonia content has been studied. The initial chlorine concentration and the temperature have a positive effect on MC-LR elimination. However, the pH exerts a negative influence on the MC-LR elimination by chlorine, which indicates that HOCl is the main active oxidant species. High concentrations of NOM and ammonia, which consume chlorine, impede the elimination of MC-LR. During the oxidation with permanganate, the initial permanganate concentration and the temperature have a positive effect on MC-LR removal, while the pH and the ammonia content do not exert any influence on its oxidation. However, high concentrations of NOM reduce the extent of oxidation of MC-LR with permanganate.

Abstract  Selective grazing by zebra mussels has altered phytoplankton communities in many North American lakes, but the specific changes are not the same in each ecosystem. Because of this variation in response, we investigated the impacts of zebra mussels oil the plankton community of Lake Champlain with two objectives: first to determine whether zebra mussels increased the dominance of potentially toxic cyanobacteria in the phytoplankton, and second to explore the impact of zebra mussels oil protozoans, rotifers, copepod nauplii, and other inicrozooplankton in the lower food web. Experiments were conducted in 200-L mesocosms filled with Lake Champlain water filtered through a 150-mu n sieve to remove macro-zooplankton. Zebra mussels were added to half of the mesocosms while the others were maintained as controls. Over a 96-hour experimental period, we tracked nitrogen and phosphorus concentration, chlorophyll a, microcystin concentration, and both phytoplankton and microzooplankton composition and abundance. We found an increase in SRP and total nitrogen concentration and a decrease in the ratio of TN.-TP in the zebra mussel treatments over time. Microcystin was undetectable throughout the experiment using the ELISA assail. Phytoplankton biovolume, including cyanobacteria biovolume, declined significantly in the zebra mussel treatments, as did rotifer, protozoan and nauplii abundance. By both direct (consumption) and indirect (altered nutrient availabilities and increased competition) means, zebra mussels clearly seem capable of strongly influencing the lower planktonic foodweb in the many shallow water habitats of Lake Champlain.

Abstract  In southern China, many freshwater ecosystems, including lakes, rivers and reservoirs, are eutrophic. The nutrient loading coupled with year-round warm weather favors the growth of cyanobacteria, several of which can produce cyanotoxins, especially the potent liver toxins called microcystins, which are often detected in eutrophic drinking water sources. For purifying raw water used as source of drinking water treatment plants, an aquatic vegetable bed (AVB) experiment had been carried out in a hypertrophic waterfront of Lake Taihu, China, since October 2002. AVB was a simplification of the nutrient film technique (NFT) used to produce vegetables, which requires large quantities of water and nutrients. The average removal rates of total microcystin-RR and microcystin-LR were 63.0% and 66.7%, respectively. This study indicated that Ipomoea aquatica was able to absorb microcystins by using enzyme-linked immunosorbent assay (ELISA), and that the roots absorbed more toxins than leaves and stems. We used fluorescence in situ hybridization (FISH) to analyze the density of microcystin-degrading bacteria in AVB sediment. TWO species of microcystin-degrading bacteria were detected, which indicated that microcystin bio-degradation processes did occur in AVB. Protozoa and metazoa were abundant in the rhizosphere. Aspidisca sp., Vorticella sp., Philodina sp., and Lecane sp. were the dominant species. The predation function of protozoa and metazoa had a positive effect on removal of cyanobacteria and microcystins. (C) 2009 Elsevier B.V. All rights reserved.

Abstract  Blooms of cyanobacteria (toxic blue-green algae) can produce health and environmental hazards in water, including water used for drinking or recreational purposes. How, why, and when these blooms are produced, as well as how to deal with them, are questions whose answers are vital to the safe-linked to guarding of public health in regions where the algae occur. The blooms are eutrophication of water, and this paper discusses the eutrophication problems, their nature, and their relevance to the production of cyanobacteria. Nutrient limitations on algal productivity are considered, as is the involvement of the atmosphere, the storage of nutrients in soils, and the influence of anthropogenic activity.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. Octanol/water partition coefficients (log Kow) for 87 chemicals representing the main classes of pesticides have been determined by means of three different estimation methods (RP-HPLC, ClogP, calculation from water solubility), and the results have been compared with experimental values (measured mainly with Slow Stirring or Shake Flask methods), collected through a survey of the literature. On the basis of a critical evaluation of all available data, a selected value for each pesticide has been proposed. Values and limitations of the three estimation methods has been discussed.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE ORGANOPHOSPHORUS PESTICIDES FOOD CONTAMINANT ORGANOCHLORINE PESTICIDES CARBAMATE PESTICIDES INSECTICIDES FUNGICIDES HERBICIDES VEGETABLE PRODUCTS FOODS VEGETABLE PRODUCT

Abstract  A spectrophotometric method for determining cholinesterase (ChE) activity in the whole blood of rats was developed. The method was based on a commercially available reagent set. The kit utilized acetylthiocholine which served as the substrate. The reaction between ChE in a blood sample produced thiocholine which was then reacted with dithiobisnitrobenzoic-acid to form 2-nitro-5-mercapto-benzoate (NMBZ). The absorbance of NMBZ was measured at 405 nanometers. NMBZ absorbance was directly proportional to the ChE activity in the sample after correcting for nonenzymatic hydrolysis of the substrate. Male Sprague-Dawley-rats were injected intravenously with 0, 50, 100, or 200 micrograms per kilogram physostigmine-salicylate (57647) (PHY). Blood samples were obtained from the lateral tail vein or from the jugular vein with a catheter 15 or 60 minutes after dosing and analyzed for ChE using the procedure. PHY induced dose dependent decreases in ChE activity. The extent of inhibition did not vary significantly between sampling sites; however, the extent of inhibition was less in samples analyzed 60 minutes after dosing compared with those obtained 15 minutes after dosing. Experiments leading to optimization of the procedure were described. The authors conclude that the spectrophotometric assay based on the commercial reagent kit can be used to determine ChE activity in rat blood. The blood samples can be taken from peripheral or central sites.

Abstract  A capillary electrophoretic method for the determination of the amino acid beta-N-methylamino-L-alanine (BMAA) was achieved using a fused-silica capillary column (50 cm x 75 pm I.D.) filled with 5 mM sodium tetraborate solution (pH 9), with an applied voltage of 25 kV, at 25 degrees C. The method was then applied in quantifying BMAA in eighteen strains of lyophilized estuarine cyanobacteria, following amino acid extraction using 0.1 M trichloroacetic acid and 6 M hydrochloric acid, sequentially. (C) 2011 Elsevier Ltd. All rights reserved.

Abstract  The kinetics of the transformation of methyl parathion have been investigated in aqueous solution containing reduced sulfur species and small concentrations of natural organic matter (NOM) from different sources such as soil, river, and peat. It was shown that NOM mediates the degradation of methyl parathion in aqueous solutions containing hydrogen sulfide. After evaluating and quantifying the effect of the NOM concentration on the degradation kinetics of methyl parathion in the presence of hydrogen sulfide, it was found that the observed pseudo-first-order reaction rate constants (k(obs)) were proportional to NOM concentrations. The influence of pH on the degradation of methyl parathion in the aqueous solutions containing hydrogen sulfide and NOM has been studied. The rate of degradation of methyl parathion was strongly pH dependent. The results indicate k(obs) with a commercially available humic acid has a maximum value at approximately pH 8.3. Two main reaction mechanisms are identified to dominate the degradation of methyl parathion in aqueous solution containing hydrogen sulfide and NOM based on the products aminomethyl parathion and desmethyl methyl parathion. The two mechanisms are nitro-group reduction and nucleophilic attack at the methoxy-carbon. The reduction of the nitro-group is only observed in the presence of NOM. The results of this study form an important base for the evaluation and interpretation of transformation processes of methyl parathion in the environment.

Abstract  BACKGROUND: Pyrethroid-resistant mosquitoes are an increasing threat to malaria vector control. The Global Plan for Insecticide Resistance Management (GPIRM) recommends rotation of non-pyrethroid insecticides for indoor residual spraying (IRS). The options from other classes are limited. The carbamate bendiocarb and the organophosphate pirimiphos-methyl (p-methyl) emulsifiable concentrate (EC) have a short residual duration of action, resulting in increased costs due to multiple spray cycles, and user fatigue. Encapsulation (CS) technology was used to extend the residual performance of p-methyl.

METHODS: Two novel p-methyl CS formulations were evaluated alongside the existing EC in laboratory bioassays and experimental hut trials in Tanzania between 2008-2010. Bioassays were carried out monthly on sprayed substrates of mud, concrete, plywood, and palm thatch to assess residual activity. Experimental huts were used to assess efficacy against wild free-flying Anopheles arabiensis, in terms of insecticide-induced mortality and blood-feeding inhibition.

RESULTS: In laboratory bioassays of An. arabiensis and Culex quinquefasciatus both CS formulations produced high rates of mortality for significantly longer than the EC formulation on all substrates. On mud, the best performing CS killed >80% of An. arabiensis for five months and >50% for eight months, compared with one and two months, respectively, for the EC. In monthly bioassays of experimental hut walls the EC was ineffective shortly after spraying, while the best CS formulation killed more than 80% of An. arabiensis for five months on mud, and seven months on concrete. In experimental huts both CS and EC formulations killed high proportions of free-flying wild An. arabiensis for up to 12 months after spraying. There was no significant difference between treatments. All treatments provided considerable personal protection, with blood-feeding inhibition ranging from 9-49% over time.

CONCLUSIONS: The long residual performance of p-methyl CS was consistent in bioassays and experimental huts. The CS outperformed the EC in laboratory and hut bioassays but the EC longevity in huts was unexpected. Long-lasting p-methyl CS formulations should be more effective than both p-methyl EC and bendiocarb considering a single spray could be sufficient for annual malaria control. IRS with p-methyl 300 CS is a timely addition to the limited portfolio of long-lasting residual insecticides.

Abstract  A series of coumarin derivatives (6-8) containing (E)-methyl 2-(methoxyimino)-2-phenylacetate, (E)-2-(methoxyimino)-N-methyl-2-phenylacetamide and methyl methoxy(phenyl)carbamate were synthesized from substituted resorcinols (1) and substituted beta-keto esters (2) as starting material via cyclization and condensation reactions. The test results indicated that (E)-methyl 2-{2-[(3-hexyl-4-methyl-coumarin-7-yloxy)methyl]phenyl}-2-(methoxyimino)acetate (6f) was the optimal structure with good fungicidal activity against cucumber grey mold (CGM) giving 100% control at 100 mg L(-1) concentration, much higher than that of coumoxystrobin. Methyl 2-[(3,4-dimethyl-coumarin -7-yloxy)methyl]phenyl(methoxy)carbamate (8a) was another optimal structure with good fungicidal activity against wheat powdery mildew (WPM) showing 100% control at 50 mg L(-1) concentration, at the same level as that of the commercial kresoxim-methyl, and very significantly higher than that of coumoxystrobin (no control against WPM at 400 mg L(-1)).

Abstract  After serving as a neurotransmitter, acetylcholine is hydrolyzed by acetylcholinesterase (AcHE), inhibition of AChE is considered to be a specific biomarker for exposure to organophosphate and carbamate insecticides. In this study, the AChE gene was isolated from hybrid catfish brain by RT-PCR methods using degenerate primers. The amplified fragment of 966 nucleotides generated by PCR was cloned, and sequence analysis showed 82% nucleotide identity with AChE of the Electrophorus electricus. Specific primers of the hybrid catfish AChE gene were then synthesized and used in the examination of AChE gene expression in brain tissue of hybrid catfish exposed to sublethal concentrations of chlorpyrifos (0.43, 4.3 and 43 mu M) and carbaryl (1.19, 11.9 and 119 mu M) for 24 fir Real-time PCR was used to compare with the amplified 28S rRNA gene. AChE gene expression was significantly elevated 12.4 times in catfish exposed to 43 PM chlorpyrifos in comparison to the control group (p<0.05). Carbaryl did not produce any significant change. These results indicate that AChE is more sensitive to administration of chlorpyrifos than carbaryl. The induction of the AChE gene indicates the possibility of using this gene as biomarker for detecting effects of organophosphate insecticides in hybrid catfish.

Abstract  The discovery of new templates and their subsequent elaboration to clinically useful receptor tyrosine kinase (RTK) inhibitors continues to be an important issue. RTKs are a class of enzymes responsible for the activation of different cellular signal transduction cascades. The majority of the known small molecules RTK inhibitors are ATP- competitive and they are multiple targeted inhibitors. We describe here serotonin derivatives as a new class of multiple targeted RTK inhibitors. In contrast to most other RTK inhibitors they act via a non-ATP-competitive (allosteric) mechanism. Furthermore, they are able to inhibit the proliferation of HUVE cells, fibroblasts and two cancer cell lines. (C) 2010 Elsevier Ltd. All rights reserved.

Abstract  Methods: This is a retrospective study conducted in the Pediatric Intensive Care Unit (PICU) of an urban multi speciality teaching and referral hospital in North India from January 1993 to June 2008 to determine the epidemiology, clinical profile, outcome and predictors of outcome in children with acute poisoning. Data of 225 children with acute poisoning was retrieved from case records with respect to demographic profile, time to presentation, PRISM score, clinical features, investigations, therapeutic measures, complications and outcome in terms of survival or death. Survivors and non-survivors were compared to determine the predictors of mortality. Results: Acute poisoning constituted 3.9% of total PICU admissions; almost all (96.9%) were accidental. The mean age of study patient's was 3.3 +/- 3.1 (range 0.10 -12) years with majority (61.3%) being toddlers (1-3 years). In the overall cohort, kerosene (27.1%) and prescription drugs (26.7%) were the most common causative agents followed by organophosphates (16.0%), corrosives (7.6%), carbamates (4.9%) and aluminum phosphide (4.9%). However the trends of the three 5-year interval (1993 till the end of 1997, 1998 till the end of 2002 and 2003 till the end of June 2008) revealed a significant decrease in kerosene, aluminum phosphide and iron with increase in organophosphate compound poisoning. Ninety nine (44%) patients required supplemental oxygen, of which nearly half (n = 42; 42.4%) needed mechanical ventilation. Twenty (8.9%) died; cause of death being iron poisoning in five; aluminum phosphide in four; organophosphates in three and one each because of kerosene, diesel, carbamate, corrosive, sewing machine lubricant, isoniazid, salicylate and maduramycin poisoning. There has been a significant decrease in the mortality over the years. The non-survivors were older, had a higher PRISM score and hypotension at admission and higher need for oxygen and ventilation. On multiple logistic regression analysis hypotension at admission was the most significant predictor of death (adjusted odds ratio: 5.59; 95% confidence interval: 1.38-22.63; p = 0.016). Conclusion: Acute poisoning in children over the past 15 years has shown a changing trend with significant decrease in kerosene, iron and aluminum phosphide and an increase in organophosphate and prescription drugs. The overall mortality has decreased significantly. Hypotension at admission was the most significant predictor of death.

Abstract  The objective of this investigation was to determine the acute toxic effects of the carbamate insecticide carbofuran on the levels of endocrine hormones in the serum of male Sprague-Dawley rats. Using chemiluminescent immunoassay, the hormones determined were progesterone, cortisol, estradiol, testosterone, triidothyronine (T3), total thyroxine (total T4), and non-protein-bound thyroxine (free T4). Rats exposed to an acute dose of carbofuran (1.5 mg/kg, s.c.) showed the onset of cholinergic signs (salivation, chewing, and fine tremors) within 5-7 min. With increasing intensity, toxic signs of maximal severity (severe convulsions and fasciculations) were observed within 30-60 min, and lasted for about 2 to 3 h. Time courses of hormones for 24 h revealed significant alterations in hormone levels during 0.5 to 3 h, with the exception of estradiol at 6 h. The levels of progesterone, cortisol, and estradiol were significantly increased (1279%, 202%, and 150%, respectively), while the levels of testosterone were decreased by 88%. No significant change occurred in thyroid hormones (T3, total T4, and free T4) at any time during the time course, despite the fact that body temperature was significantly low at 1 to 2 h after carbofuran injection. Carbofuran caused a >2-fold increase in glucose during early hours of toxicity. The results suggest that an acute exposure to carbofuran may cause transient endocrine disruption, which may consequently lead to serious reproductive problems following repeated exposure.

Abstract  Mofegiline or MDL 72,974A ((E)-4-fluoro-beta-fluoromethylene benzene butanamine hydrochloride) is a selective enzyme-activated irreversible inhibitor of monoamine oxidase B, which is under development for use in the treatment of Parkinson's disease. Male beagle dogs were given single p.o. (20 mg/kg) and i.v. (5 mg/kg) doses of [14C]-Mofegiline. Total radioactivity excreted in urine and feces over 96 hr was, respectively, 75.5 +/- 3.8 and 6.3 +/- 3.4% of the dose after p.o. and 67.9 +/- 0.5 and 3.9 +/- 2.4% after i.v. administration. Unchanged drug in urine represented 3% of the dose after po and less than 1% after i.v. administration. Mofegiline was thus extensively metabolized in dogs, and urinary excretion was the major route of elimination of metabolites. HPLC, with on-line radioactivity detection, showed the presence of four major peaks (M1, M2, M3, and M4), representing respectively 50, 9, 5, and 0.5% of the administered dose excreted in 0-24 hr urine. TSP-LC-MS, FAB-MS, and NMR spectra of the purified metabolites were obtained. M1, the major metabolite in dogs, was shown to have undergone defluorination of the beta-fluoromethylene moiety, and one carbon addition. Its structure was confirmed to be a cyclic carbamate. M2 was a N-carbamoyl O-beta-D-glucuronide conjugate of parent drug. The formation of M1 and M2 is likely to involve initial reversible addition of CO2 to the primary amine function. M3 was a N-succinyl conjugate of the parent drug. M4 had also undergone defluorination to yield a urea adduct of an unsaturated alpha, beta aldehyde. Structures of M1 and M3 were further confirmed by comparing their MS and NMR spectra with those of authentic reference compounds. TSP-LC-MS ion chromatograms of human urine, obtained from two male volunteers after p.o. administration of 24 mg of drug, showed selected molecular ion peaks with the same retention time as the metabolites identified in dogs. In humans, these common metabolites represented a similar percentage of the administered dose to that in dogs. The present study demonstrates that NMR, TSP-LC-MS are complementary analytical techniques, which allow structural identification of unhydrolyzed drug conjugates. The formation of carbamates of amine-containing drugs may be more common than previously reported.

Abstract  Mass appearances of the toxic dinoflagellate genus Ostreopsis are known to cause dangerous respiratory symptoms in humans exposed to aerosols. The outbreaks can appear in shallow marine waters of temperate regions around the globe. We followed a massive bloom event on a public beach on the northern Adriatic coast near Rovinj, Croatia. We identified the responsible species and the produced toxins as well as the dynamics of the event with respect to environmental conditions. Ostreopsis cf. ovata appeared in masses from September through October 2010 on a public beach near Rovinj, Croatia but stayed undetected by public health organizations. Respiratory symptoms were observed whenever humans were exposed to substrate samples containing large numbers of Ostreopsis cells. During the mass abundance of O. cf. ovata also exposure to the aerosols on the beach evoked respiratory symptoms in humans. Our measurements showed high cell abundances and high toxin contents with a stable relative contribution of putative Palytoxin and Ovatoxins a-e. Artificial beach structures proved to dramatically reduce settling of the observed Ostreopsis biofilm. Blooms like those reported herein have a high potential to happen undetected with a high potential of affecting the health of coastal human populations. Increased monitoring efforts are therefore required to understand the ecology and toxicology of those bloom events and reduce their negative impact on coastal populations.

Abstract  Atmospheric deposition of nutrients (N and P species) can intensify anthropogenic eutrophication of coastal waters. It was found that the atmospheric wet and dry depositions of nutrients was remarkable in the Southeast Asian region during the course of smoke haze events, as discussed in a companion paper on field observations (Sundarambal et al., 2010b). The importance of atmospheric deposition of nutrients in terms of their biological responses in the coastal waters of the Singapore region was investigated during hazy days in relation to non-hazy days. The influence of atmospherically-derived, bio-available nutrients (both inorganic and organic nitrogen and phosphorus species) on the coastal water quality between hazy and non-hazy days was studied. A numerical modeling approach was employed to provide qualitative and quantitative understanding of the relative importance of atmospheric and ocean nutrient fluxes in this region. A 3-D eutrophication model, NEUTRO, was used with enhanced features to simulate the spatial distribution and temporal variations of nutrients, plankton and dissolved oxygen due to atmospheric nutrient loadings. The percentage increase of the concentration of coastal water nutrients relative to the baseline due to atmospheric deposition was estimated between hazy and non-hazy days. Model computations showed that atmospheric deposition fluxes of nutrients might account for up to 17 to 88% and 4 to 24% of total mass of nitrite + nitrate-nitrogen in the water column, during hazy days and non-hazy days, respectively. The results obtained from the modeling study could be used for a better understanding of the energy flow in the coastal zone system, exploring various possible scenarios concerning the atmospheric deposition of nutrients onto the coastal zone and studying their impacts on water quality.

Abstract  RATIONALE: Cyanobacteria are a small group of photosynthetic planktonic bacteria, producing a large group of strong hepatotoxins called microcystins (MCs). Many studies have been conducted to evaluate the presence of MCs and nodularin (NOD) in water or in marine organisms, but little research has been done on the atmospheric environment. Waterborne toxins can be found in the aerosol phase due to bubble-bursting processes.

METHODS: The aim of this study was to obtain a sensitive method for the simultaneous determination of trace concentrations of individual cyanotoxins in aerosol samples, using liquid chromatography coupled with a triple quadrupole (HPLC/MS/MS). During method development improved electrospray ionization was found in negative ion mode. In contrast with other authors, we have developed a chromatographic separation using alkaline conditions, thus achieving good resolution, improved electrospray ionization and therefore better sensitivity.

RESULTS: A sensitive analytical method was set up to simultaneously measure trace concentrations of cyanotoxins in aerosol samples in a single chromatographic analysis using the internal standard method. The limit of detection for all the toxins was determined to be between 1 fg/μL (MC LA and LF) and 9 fg/μL (NOD).

CONCLUSIONS: The method was applied to ten aerosol samples from the Venice Lagoon. In these samples, trace concentrations of MC-LA ranging between 90 fg m(-3) and 706 fg m(-3), MC-LF between n.d. and 369 fg m(-3) and MC-LW between n.d. and 262 fg m(-3). This is the first study to quantify the cyanotoxins in Venetian aerosol samples using the HPLC/(-)ESI-MS/MS.

Abstract  The aims of this study were to investigate the population dynamics and distribution of cyanobacteria in three New Zealand lakes, to detect the presence of microcystin-producing mcyE genes in potentially toxigenic strains and to correlate the finding with microcystin production. A total of 18 samples collected over a 6-week period from Lakes Rotorua, Rotoiti and Rotoehu were found to be predominantly composed of Microcystis spp., Anabaena spp., Coelosphaerium spp. and Aphanocapsa spp. The 820-bp-longregion of the microcystin synthetase gene (mcyE) was successfully amplified for 11 out of the 18 water samples in genera of Microcystis and Anabaena. This provides the first documented evidence of Anabaena sp. carrying the potential to produce microcystins in New Zealand. Microcystin-LR was the only variant detected by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) analysis and was present in all samples from Lake Rotoehu.

Abstract  During the summer of 2006, the western basin of Lake Erie experienced a bloom of the toxigenic cyanobacterium Microcystis aeruginosa. Across 11 sites, intracellular, particulate-bound microcystin levels in the seston increased to levels that exceeded World Health Organization guidelines for drinking water exposure (1 mu g toxin-L(-1)). In contrast, toxin concentrations in yellow perch (Perca flavescens) muscle tissue (n = 68) declined from June to August, were negatively related to algal toxin levels, and never exceeded a conservative chronic exposure concentration estimated using proposed United States Environmental Protection Agency (US EPA) guidelines. Microcystin concentrations in yellow perch liver exceeded US EPA chronic exposure guidelines, were on average 125 times higher than muscle toxin concentrations per unit dry weight, and varied little throughout the summer. With current guidelines, humans do not appear to be at risk when consuming the muscle tissue of Lake Erie yellow perch collected during large-scale cyanobacterial blooms. However, this study highlights the need for a better understanding of the trophic transfer of cyanobacterial toxins through aquatic food webs in diverse ecosystems with an emphasis on understanding if these compounds could accumulate sufficiently to affect human health.

Abstract  OBJECTIVES: Parasites have recently been recognized as accumulation indicators that take up and bio-concentrate substances from environmental pollution. Interestingly, helminths of fish are known to accumulate metals from the ambient environment and to contain several orders of magnitude higher concentrations than hosts. While the majority of reports mention inorganic toxin accumulation in parasites, studies concerning effects of organic pollution are infrequent and little is known about the potential of parasites to bio-accumulate microcystins.

METHODS: The parasite-host system of tapeworm Khawia sinensis and common carp (Cyprinus carpio) was used to address this issue. Both the tapeworms and livers were dissected from experimental carps orally exposed to cyanobacterial biomass for 20 days. The total dose of microcystins amounted to 27 mg/kg of feed, i.e., 0.4 mg/kg of fish mass a day. Microcystin concentrations in tapeworms and carp liver tissues were measured using the LC-MS/MS method.

RESULTS: Considering the three measured microcystin variants LR, YR and RR, only MC-RR was detected and its concentrations in tapeworms and carp liver tissue amounted to 5.78±3.78 ng/g and 2.11±0.74 ng/g fresh weight (p<0.05), respectively.

CONCLUSIONS: Here we show accumulation of microcystin MC-RR in the tapeworm Khawia sinensis, a parasite of common carp (Cyprinus carpio). As this is the first report addressing this issue, further studies will be necessary to examine this specific parasite-host system.