ITREOH Building of Regional Capacity to Monitor Recreational Water: Development of a Non-commercial Microcystin ELISA and Its Impact on Public Health Policy

Rapid freshwater discharge on the coastal ocean as a mean of long distance spreading of an unprecedented toxic cyanobacteria bloom

Cyanobacterial toxic blooms are a worldwide problem. The Río de la Plata (RdlP) basin makes up about one fourth of South America areal surface, second only to the Amazonian. Intensive agro-industrial land use and the construction of dams have led to generalized eutrophication of main tributaries and increased the intensity and duration of cyanobacteria blooms. Here we analyse the evolution of an exceptional bloom at the low RdlP basin and Atlantic coast during the summer of 2019. A large array of biological, genetic, meteorological, oceanographic and satellite data is combined to discuss the driving mechanisms. The bloom covered the whole stripe of the RdlP estuary and the Uruguayan Atlantic coasts (around 500 km) for approximately 4 months. It was caused by the Microcystis aeruginosa complex (MAC), which produces hepatotoxins (microcystin). Extreme precipitation in the upstream regions of Uruguay and Negro rivers' basins caused high water flows and discharges. The evolution of meteorological and oceanographic conditions as well as the similarity of organisms' traits in the affected area suggest that the bloom originated in eutrophic reservoirs at the lower RdlP basin, Salto Grande in the Uruguay river, and Negro river reservoirs. High temperatures and weak Eastern winds prompted the rapid dispersion of the bloom over the freshwater plume along the RdlP northern and Atlantic coasts. The long-distance rapid drift allowed active MAC organisms to inoculate freshwater bodies from the Atlantic basin, impacting environments relevant for biodiversity conservation. Climate projections for the RdlP basin suggest an increase in precipitation and river water flux, which, in conjunction with agriculture intensification and dams' construction, might turn this extraordinary event into an ordinary situation.

Assessing the origin of a massive cyanobacterial bloom in the Río de la Plata (2019): Towards an early warning system

The Río de la Plata estuary drains the second largest river basin of South America. The occurrence of frequent cyanobacterial blooms of the Microcystis and Dolichospermum complex in the Uruguayan coast are associated with high flows of Uruguay River due to rainy years. In summer 2019, a massive cyanobacterial bloom reached up to the Uruguayan Atlantic coast. This study seeks to unveil the origin and the environmental conditions that favored the occurrence of the last cyanobacterial bloom in the Río de la Plata, and to contribute with the development of an early warning system of cyanobacterial scum on Montevideo beaches. A complementary approach was applied with Sentinel-2 imagery, environmental data of monitoring programs of Salto Grande Reservoir and Montevideo beaches, hydro-meteorological information, and hydroelectric dam operation. Images were analyzed with the Normalized Difference Chlorophyll Index (NDCI), which allowed evaluating several water bodies within the same ranges. Positive anomalous rainfall increased river flows, particularly that of Uruguay and Negro rivers, which caused the opening of the dam spillways. NDCI maps showed that areas with high values (NDCI_>0.06) in Salto Grande reservoir kept a similar surface area before and after the prolonged overflow period (8.7-7.8 km², before and after). In the Río Negro reservoirs, however, NDCI_>0.06 coverage remarkably changed (62.5 km², Palmar reservoir), with a subsequent 56-fold reduction in the post-discharge of surface water. Twenty days after opening the spillways, Montevideo beaches were closed to swimming and the NDCI_>0.06 surface reached 51.7 km² in the Río de la Plata coast. The dynamics of NDCI areas, the downstream bloom discharge, and the predicted Río de la Plata residual currents, suggest that the cyanobacterial bloom originated in the Negro River (Palmar reservoir). This bloom event was one of the worst that occurred in the Río de la Plata in last 20 years, circulated along the Uruguayan sub-corridor to the Atlantic coast along 690 km from its origin, and lasted three months on Montevideo coast. This is the first study that addresses the impact of cyanobacterial blooms from the Negro River reservoirs on the Río de la Plata estuary. Therefore, the Negro River basin is where the main efforts should be directed to mitigate massive cyanobacterial blooms.

Recreational Exposure during Algal Bloom in Carrasco Beach, Uruguay: A Liver Failure Case Report

In January 2015, a 20-month-old child and her family took part in recreational activities at Carrasco and Malvín beaches (Montevideo, Uruguay). An intense harmful algae bloom (HAB) was developing along the coast at that time. A few hours after the last recreational exposure episode, the family suffered gastrointestinal symptoms which were self-limited except in the child's case, who was admitted to hospital in Uruguay with diarrhea, vomiting, fatigue, and jaundice. The patient had increased serum levels of liver enzymes and bilirubin and five days later presented acute liver failure. She was referred to the Italian Hospital in Buenos Aires, being admitted with grade II-III encephalopathy and hepatomegaly and requiring mechanical respiratory assistance. Serology tests for hepatitis A, B, and C, Epstein-Barr virus, and cytomegalovirus were negative. Laboratory features showed anemia, coagulopathy, and increased serum levels of ammonium, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and bilirubin. Autoimmune Hepatitis Type-II (AH-II) was the initial diagnosis based on a liver kidney microsomal type 1 antibodies (LKM-1) positive result, and twenty days later a liver transplant was performed. The liver histopathology had indicated hemorrhagic necrosis in zone 3, and cholestasis and nodular regeneration, which were not characteristic of AH-II. LC/ESI-HRMS (liquid chromatography electrospray ionization high-resolution mass spectrometry) analysis of MCs in the explanted liver revealed the presence of Microsytin-LR (MC-LR) (2.4 ng·gr-1 tissue) and [D-Leu¹]MC-LR (75.4 ng·gr-1 tissue), which constitute a toxicological nexus and indicate a preponderant role of microcystins in the development of fulminant hepatitis.

Cellular transport of microcystin-LR in rainbow trout (Oncorhynchus mykiss) across the intestinal wall: possible involvement of multidrug resistance-associated proteins

We studied Abcc mediated-transport in middle and posterior intestine of the rainbow trout, Oncorhynchus mykiss. Luminal and serosal transport were evaluated in everted and non-everted intestinal sacs, respectively, incubated with 1-chloro-2,4-dinitrobenzene (CDNB; 200 μM). CDNB enters the cells and is conjugated with glutathione via glutathione S-transferase (GST) to form 2,4-dinitrophenyl-S-glutathione (DNP-SG), a known Abcc substrate. DNP-SG concentration in the bath was recorded every 10 min, in order to calculate the mass-specific transport rate. For evaluating the possible involvement of Abcc proteins in microcystin-LR (MCLR) transport, 1.135 μM MCLR was added to the bath or inside the sacs, in everted or non-everted preparations, respectively. Both luminal and serosal DNP-SG efflux were significantly inhibited by MCLR. A concentration-response curve obtained using strips from middle intestine yielded an IC50 value of 1.33 μM MCLR. The Abcc inhibitor, MK571 produced concentration-dependent inhibition of DNP-SG similar to that produced by MCLR. Since competition of MCLR and CDNB as GST substrates could bias the DNP-SG transport results, we evaluated the effects of MCLR on calcein efflux, which does not depend on GST activity. We applied the non-fluorescent, cell-permeant compound calcein-AM (0.25 μM) to middle intestinal strips and recorded the efflux of its hydrolysis product, the fluorescent Abcc substrate calcein. 2.27 μM MCLR and 3 μM MK571 inhibited calcein efflux (17.39 and 20.2%, respectively). Finally, MCLR interaction with Abcc transporters was evaluated by measuring its toxic intracellular effects. Middle intestinal segments were incubated in saline solution with 1.135 μM MCLR (MC1), 2.27 μM MCLR (MC2), 3 μM MK571 (MK) or 1.135 μM MCLR+3 μM MK571 (MC1/MK). After 1h, GSH concentration, protein phosphatase 1 and 2A (PP1, PP2A) and GST activities were measured in each segment. MC1did not produce significant effect while MC1/MK and MC2 significantly inhibited PP1and PP2A in similar proportions (34-49%). MK alone significantly increased PP2A activity (40%) with no effect in any other variable. GST activity and GSH concentration were not affected by any treatment. Concentration-response curves for MCLR (1.135 to 13.62 μM) alone or plus 3 or 6 μM MK571 were obtained using PP1 activity as response variable. The IC50 values were 1.0, 0.52, and 0.37 μM, respectively. Our results suggest that O. mykiss enterocytes are capable of eliminating MCLR by GST-mediated conjugation and luminal excretion through an Abcc-like apical transporter. This mechanism would prevent toxic effects and reduce the toxin uptake into the blood, which is likely mediated by basolateral Abccs.

Rapid quantitative analysis of microcystins in raw surface waters with MALDI MS utilizing easily synthesized internal standards

The freshwater cyanotoxins, microcystins (MCs), pose a global public health threat as potent hepatotoxins in cyanobacterial blooms; their persistence in drinking and recreational water has been associated with potential chronic effects in addition to acute intoxications. Rapid and accurate detection of the over 80 structural congeners is challenged by the rigorous and time consuming clean up required to overcome interference found in raw water samples. MALDI-MS has shown promise for rapid quantification of individual congeners in raw water samples, with very low operative cost, but so far limited sensitivity and lack of available and versatile internal standards (ISs) has limited its use. Two easily synthesized S-hydroxyethyl-Cys(7)-MC-LR and -RR ISs were used to generate linear standard curves in a reflectron MALDI instrument, reproducible across several orders of magnitude for MC-LR, -RR and -YR. Minimum quantification limits in direct water samples with no clean up or concentration step involved were consistently below 7 μg/L, with recoveries from spiked samples between 80 and 119%. This method improves sensitivity by 30 fold over previous reports of quantitative MALDI-TOF applications to MCs and provides a salient option for rapid throughput analysis for multiple MC congeners in untreated raw surface water blooms as a means to identify source public health threats and target intervention strategies within a watershed. As demonstrated by analysis of a set of samples from Uruguay, utilizing the reaction of different MC congeners with alternate sulfhydryl compounds, the m/z of the IS can be customized to avoid overlap with interfering compounds in local surface water samples.

Accumulation and biochemical effects of microcystin-LR on the Patagonian pejerrey (Odontesthes hatcheri) fed with the toxic cyanobacteria Microcystis aeruginosa

We studied accumulation and biochemical effects of microcystin-LR (MCLR) in Odontesthes hatcheri after dietary administration of the cyanobacteria Microcystis aeruginosa (1.3 μg MCLR/g body mass, incorporated in standard fish food). After 12 h, MCLR content in liver did not differ between fish fed with crushed or intact cells, demonstrating O. hatcheri's capacity to digest cyanobacteria and absorb MCLR. In the second experiment, fish received toxic cells, non-toxic cells, or control food; MCLR accumulation was monitored for 48 h. Protein phosphatase 1 (PP1), catalase (CAT), glutathione-S-transferase (GST) activities, and lipid peroxidation (as MDA) were measured in liver and intestine. Methanol-extractable MCLR was determined by PP1 inhibition assay (PPIA); extractable and protein-bound MCLR were measured by Lemieux oxidation-gas chromatography/mass spectrometry (GC/MS). MCLR accumulated rapidly up to 22.9 and 9.4 μg MCLR/g in intestine and liver, respectively, followed by a decreasing tendency. Protein-bound MCLR represented 66 to ca. 100 % of total MCLR in both tissues. PP1 activity remained unchanged in intestine but was increased in liver of MCLR treated fish.CAT and GST activities and MDA content were significantly increased by MCLR only in liver. We conclude that O. hatcheri is able to digest cyanobacteria, accumulating MCLR mostly bound to proteins. Our data suggest that this freshwater fish can be adversely affected by cyanobacterial blooms. However, the rapid decrease of the detectable MCLR in both tissues could imply that sublethal toxin accumulation is rapidly reversed.

Microcystins in potable surface waters: toxic effects and removal strategies

In freshwater, harmful cyanobacterial blooms threaten to increase with global climate change and eutrophication of surface waters. In addition to the burden and necessity of removal of algal material during water treatment processes, bloom-forming cyanobacteria can produce a class of remarkably stable toxins, microcystins, difficult to remove from drinking water sources. A number of animal intoxications over the past 20 years have served as sentinels for widespread risk presented by microcystins. Cyanobacterial blooms have the potential to threaten severely both public health and the regional economy of affected communities, particularly those with limited infrastructure or resources. Our main objectives were to assess whether existing water treatment infrastructure provides sufficient protection against microcystin exposure, identify available options feasible to implement in resource-limited communities in bloom scenarios and to identify strategies for improved solutions. Finally, interventions at the watershed level aimed at bloom prevention and risk reduction for entry into potable water sources were outlined. We evaluated primary studies, reviews and reports for treatment options for microcystins in surface waters, potable water sources and treatment plants. Because of the difficulty of removal of microcystins, prevention is ideal; once in the public water supply, the coarse removal of cyanobacterial cells combined with secondary carbon filtration of dissolved toxins currently provides the greatest potential for protection of public health. Options for point of use filtration must be optimized to provide affordable and adequate protection for affected communities.

Limited analytical capacity for cyanotoxins in developing countries may hide serious environmental health problems: simple and affordable methods may be the answer

In recent years, the international demand for commodities has prompted enormous growth in agriculture in most South American countries. Due to intensive use of fertilizers, cyanobacterial blooms have become a recurrent phenomenon throughout the continent, but their potential health risk remains largely unknown due to the lack of analytical capacity. In this paper we report the main results and conclusions of more than five years of systematic monitoring of cyanobacterial blooms in 20 beaches of Montevideo, Uruguay, on the Rio de la Plata, the fifth largest basin in the world. A locally developed microcystin ELISA was used to establish a sustainable monitoring program that revealed seasonal peaks of extremely high toxicity, more than one-thousand-fold greater than the WHO limit for recreational water. Comparison with cyanobacterial cell counts and chlorophyll-a determination, two commonly used parameters for indirect estimation of toxicity, showed that such indicators can be highly misleading. On the other hand, the accumulated experience led to the definition of a simple criterion for visual classification of blooms, that can be used by trained lifeguards and technicians to take rapid on-site decisions on beach management. The simple and low cost approach is broadly applicable to risk assessment and risk management in developing countries.

Fifteen years of occupational and environmental health projects support in Brazil, Chile, and Mexico: a report from Mount Sinai School of Medicine ITREOH program, 1995-2010

BACKGROUND

The Fogarty International Center of the National Institutes of Health created the International Training and Research Program in Occupational and Environmental Health (ITREOH program) in 1995 with the aim to train environmental and occupational health scientists in developing countries. Mount Sinai School of Medicine was a grantee of this program since its inception, partnering with research institutions in Brazil, Chile, and Mexico. This article evaluates Mount Sinai's program in order to determine whether it has contributed to the specific research capacity needs of the international partners.

METHODS

Information was obtained from: (a) international and regional scientific literature databases; (b) databases from the three participating countries; and (c) MSSM ITREOH Program Database.

RESULTS

Most of the research projects supported by the program were consistent with the themes found to be top priorities for the partner countries based on mortality/morbidity and research themes in the literature. Indirect effects of the training and the subsequent research projects completed by the trained fellows in the program included health policy changes and development of collaborative international projects.

CONCLUSION

International research training programs, such as the MSSM ITREOH, that strengthen scientific research capacity in occupational and environmental health in Latin America can make a significant impact on the most pressing health issues in the partner countries.

The chemistry and biology of organic guanidine derivatives

The chemistry and biology of organic natural guanidines are reviewed, including the isolation, structure determination, synthesis, biosynthesis and biological activities of alkaloids, non-ribosomal peptides, guanidine-bearing terpenes, polyketides and shikimic acid derivatives from natural sources.

Microcystin accumulation and antioxidant responses in the freshwater clam Diplodon chilensis patagonicus upon subchronic exposure to toxic Microcystis aeruginosa

We investigated the accumulation and toxicity of microcystin-LR (MCLR) in the digestive gland of the freshwater clam Diplodon chilensis patagonicus. Treated clams were fed with a toxic strain of Microcystis aeruginosa (NPJB1) during 6 weeks and control clams received the non-toxic strain NPDC1. Filtration rate was estimated for both groups. Toxic effects were evaluated through the hepatosomatic index (HSI) and different oxidative stress biomarkers, lipid peroxidation (content of thiobarbituric reactive substances-TBARS), protein oxidation (carbonyl groups) and reduced glutathione (GSH) levels, and enzymatic activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST). The extractable MCLR measured by ELISA in digestive gland extracts showed little or no change during the first 3 weeks and increased significantly at weeks 5 and 6. HSI was reduced by 30% in treated clams at weeks 5 and 6. No significant oxidative damage to lipids or proteins was. All the antioxidant defense parameters analyzed were significantly increased at week 5 or 6. GSH increased in treated clams at week 5, reaching 62% increase at week 6. SOD, CAT and GST activities were significantly increased in treated clams by 50%, 66% and 60%, respectively, at the end of the experiment. D. chilensis patagonicus can be exposed to prolonged cyanobacterial blooms accumulating significant quantities of MCLR, which could be a risk for mammals and birds, which feed on this species and, in a lesser extent, to humans.