A step towards tuning the jute fiber structure and properties by employing sodium periodate oxidation and coating with alginate.

This paper outlines a novel simple protocol for tuning the structure and properties of jute using sodium periodate (NaIO4) oxidation and coating with alginate. When compared to the raw jute, fabrics oxidized with a 0.2 or 0.4 % NaIO4 solution for 30-120 min exhibited an increased aldehyde group content (0.185 vs. 0.239-0.398 mmol/g), a significantly increased negative zeta potential (from -8.57 down to -20.12 mV), a slight disruption of fiber crystallinity, 15.1-37.5 % and 27.9-49.8 % lower fabric maximum force and stiffness, respectively. Owing to the removal of hydrophobic surface barrier, decreased crystallinity index and the presence of micropores on the fabrics' surfaces, oxidized fabrics have a 22.3-29.6 % improved ability for moisture sorption compared to raw fabric. Oxidized fabrics characterized by very long wetting times and excellent antioxidant activities (> 98 %), can find applications as hydrophobic packaging materials. To further extend the utilization of jute in biocarpet engineering such as water-binding geo-prebiotic supports, oxidized fabrics were coated with alginate resulting in 7.9-24.9 % higher moisture sorption and 352-660 times lower wetting times than their oxidized counterparts. This modification protocol has never been applied to lignocellulosic fibers and sheds new light on obtaining jute fabrics with tuned structure and properties intended for various applications.

Preparation and Characterization of Alginate Hydrogels with High Water-Retaining Capacity.

Hydrogels are very attractive materials due to their multifunctional properties. Many natural polymers, such as polysaccharides, are used for the preparation of hydrogels. The most important and commonly used polysaccharide is alginate because of its biodegradability, biocompatibility, and non-toxicity. Since the properties of alginate hydrogel and its application depend on numerous factors, this study aimed to optimize the gel composition to enable the growth of inoculated cyanobacterial crusts for suppressing the desertification process. The influence of alginate concentration (0.1-2.9%, m/v) and CaCl2 concentration (0.4-4.6%, m/v) on the water-retaining capacity was analyzed using the response surface methodology. According to the design matrix, 13 formulations of different compositions were prepared. The water-retaining capacity was defined as the system response maximized in optimization studies. The optimal composition of hydrogel with a water-retaining capacity of about 76% was obtained using 2.7% (m/v) alginate solution and 0.9% (m/v) CaCl2 solution. Fourier transform infrared spectroscopy was used for the structural characterization of the prepared hydrogels, while the water content and swelling ratio of hydrogels were determined using gravimetric methods. It was concluded that alginate and CaCl2 concentrations play the most important role regarding the gelation time, homogeneity, water content, and swelling ratio of the hydrogel.

Biotests in Cyanobacterial Toxicity Assessment-Efficient Enough or Not?

Cyanobacteria are a diverse group of organisms known for producing highly potent cyanotoxins that pose a threat to human, animal, and environmental health. These toxins have varying chemical structures and toxicity mechanisms and several toxin classes can be present simultaneously, making it difficult to assess their toxic effects using physico-chemical methods, even when the producing organism and its abundance are identified. To address these challenges, alternative organisms among aquatic vertebrates and invertebrates are being explored as more assays evolve and diverge from the initially established and routinely used mouse bioassay. However, detecting cyanotoxins in complex environmental samples and characterizing their toxic modes of action remain major challenges. This review provides a systematic overview of the use of some of these alternative models and their responses to harmful cyanobacterial metabolites. It also assesses the general usefulness, sensitivity, and efficiency of these models in investigating the mechanisms of cyanotoxicity expressed at different levels of biological organization. From the reported findings, it is clear that cyanotoxin testing requires a multi-level approach. While studying changes at the whole-organism level is essential, as the complexities of whole organisms are still beyond the reach of in vitro methodologies, understanding cyanotoxicity at the molecular and biochemical levels is necessary for meaningful toxicity evaluations. Further research is needed to refine and optimize bioassays for cyanotoxicity testing, which includes developing standardized protocols and identifying novel model organisms for improved understanding of the mechanisms with fewer ethical concerns. In vitro models and computational modeling can complement vertebrate bioassays and reduce animal use, leading to better risk assessment and characterization of cyanotoxins.

Environmental Neurotoxin ß-N-Methylamino-L-alanine (BMAA) as a Widely Occurring Putative Pathogenic Factor in Neurodegenerative Diseases.

In the present review we have discussed the occurrence of ß-N-methylamino-L-alanine (BMAA) and its natural isomers, and the organisms and sample types in which the toxin(s) have been detected. Further, the review discusses general pathogenic mechanisms of neurodegenerative diseases, and how modes of action of BMAA fit in those mechanisms. The biogeography of BMAA occurrence presented here contributes to the planning of epidemiological research based on the geographical distribution of BMAA and human exposure. Analysis of BMAA mechanisms in relation to pathogenic processes of neurodegeneration is used to critically assess the potential significance of the amino acid as well as to identify gaps in our understanding. Taken together, these two approaches provide the basis for the discussion on the potential role of BMAA as a secondary factor in neurodegenerative diseases, the rationale for further research and possible directions the research can take, which are outlined in the conclusions.

A review and assessment of cyanobacterial toxins as cardiovascular health hazards.

Eutrophicated waters frequently support bloom-forming cyanobacteria, many of which produce potent cyanobacterial toxins (cyanotoxins). Cyanotoxins can cause adverse health effects in a wide range of organisms where the toxins may target the liver, other internal organs, mucous surfaces and the skin and nervous system. This review surveyed more than 100 studies concerning the cardiovascular toxicity of cyanotoxins and related topics. Over 60 studies have described various negative effects on the cardiovascular system by seven major types of cyanotoxins, i.e. the microcystin (MC), nodularin (NOD), cylindrospermopsin (CYN), anatoxin (ATX), guanitoxin (GNTX), saxitoxin (STX) and lyngbyatoxin (LTX) groups. Much of the research was done on rodents and fish using high, acutely toxin concentrations and unnatural exposure routes (such as intraperitoneal injection), and it is thus concluded that the emphasis in future studies should be on oral, chronic exposure of mammalian species at environmentally relevant concentrations. It is also suggested that future in vivo studies are conducted in parallel with studies on cells and tissues. In the light of the presented evidence, it is likely that cyanotoxins do not constitute a major risk to cardiovascular health under ordinary conditions met in everyday life. The risk of illnesses in other organs, in particular the liver, is higher under the same exposure conditions. However, adverse cardiovascular effects can be expected due to indirect effects arising from damage in other organs. In addition to risks related to extraordinary concentrations of the cyanotoxins and atypical exposure routes, chronic exposure together with co-existing diseases could make some of the cyanotoxins more dangerous to cardiovascular health.

Assessment of Common Cyanotoxins in Cyanobacteria of Biological Loess Crusts.

Cyanotoxins are a diverse group of bioactive compounds produced by cyanobacteria that have adverse effects on human and animal health. While the phenomenon of cyanotoxin production in aquatic environments is well studied, research on cyanotoxins in terrestrial environments, where cyanobacteria abundantly occur in biocrusts, is still in its infancy. Here, we investigated the potential cyanotoxin production in cyanobacteria-dominated biological loess crusts (BLCs) from three different regions (China, Iran, and Serbia) and in cyanobacterial cultures isolated from the BLCs. The presence of cyanotoxins microcystins, cylindrospermopsin, saxitoxins, and ß-N-methylamino-L-alanine was analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, while the presence of cyanotoxin-encoding genes (mcyE, cyrJ, sxtA, sxtG, sxtS, and anaC) was investigated by polymerase chain reaction (PCR) method. We could not detect any of the targeted cyanotoxins in the biocrusts or the cyanobacterial cultures, nor could we amplify any cyanotoxin-encoding genes in the cyanobacterial strains. The results are discussed in terms of the biological role of cyanotoxins, the application of cyanobacteria in land restoration programs, and the use of cyanotoxins as biosignatures of cyanobacterial populations in loess research. The article highlights the need to extend the field of research on cyanobacteria and cyanotoxin production to terrestrial environments.

Cyanobacteria, cyanotoxins, and their histopathological effects on fish tissues in Fehérvárcsurgó reservoir, Hungary.

Cyanobacteria are important members of lake plankton, but they have the ability to form blooms and produce cyanotoxins and thus cause a number of adverse effects. Freshwater ecosystems around the world have been investigated for the distribution of cyanobacteria and their toxins and the effects they have on the ecosystems. Similar research was performed on the Fehérvárcsurgó reservoir in Hungary during 2018. Cyanobacteria were present and blooming, and the highest abundance was recorded in July (2,822,000 cells/mL). The species present were Aphanizomenon flos-aquae, Microcystis flos-aquae, Microcystis wesenbergii, Cuspidothrix issatschenkoi, Dolichospermum flos-aquae, and Snowella litoralis. In July and September, the microcystin encoding gene mcyE and the saxitoxin encoding gene sxtG were amplified in the biomass samples. While a low concentration of microcystin-RR was found in one water sample from July, analyses of Abramis brama and Carassius gibelio caught from the reservoir did not show the presence of the investigated microcystins in the fish tissue. However, several histopathological changes, predominantly in gills and kidneys, were observed in the fish, and the damage was more severe during May and especially July, which coincides with the increase in cyanobacterial biomass during the summer months. Cyanobacteria may thus have adverse effects in this ecosystem.

Does the Kis-Balaton Water Protection System (KBWPS) Effectively Safeguard Lake Balaton from Toxic Cyanobacterial Blooms?

Lake Balaton is the largest shallow lake in Central Europe. Its water quality is affected by its biggest inflow, the Zala River. During late 20th century, a wetland area named the Kis-Balaton Water Protection System (KBWPS) was constructed in the hopes that it would act as a filter zone and thus ameliorate the water quality of Lake Balaton. The aim of the present study was to test whether the KBWPS effectively safeguards Lake Balaton against toxic cyanobacterial blooms. During April, May, July and September 2018, severe cyanobacterial blooming was observed in the KBWPS with numbers reaching up to 13 million cells/mL at the peak of the bloom (July 2018). MC- and STX-coding genes were detected in the cyanobacterial biomass. Five out of nine tested microcystin congeners were detected at the peak of the bloom with the concentrations of MC-LR reaching 1.29 µg/L; however, accumulation of MCs was not detected in fish tissues. Histopathological analyses displayed severe hepatopancreas, kidney and gill alterations in fish obtained throughout the investigated period. In Lake Balaton, on the other hand, cyanobacterial numbers were much lower; more than 400-fold fewer cells/mL were detected during June 2018 and cyanotoxins were not detected in the water. Hepatic, kidney and gill tissue displayed few alterations and resembled the structure of control fish. We can conclude that the KBWPS acts as a significant buffering zone, thus protecting the water quality of Lake Balaton. However, as MC- and STX-coding genes in the cyanobacterial biomass were detected at both sites, regular monitoring of this valuable ecosystem for the presence of cyanobacteria and cyanotoxins is of paramount importance.

Challenges of using blooms of Microcystis spp. in animal feeds: A comprehensive review of nutritional, toxicological and microbial health evaluation.

Microcystis spp., are Gram-negative, oxygenic, photosynthetic prokaryotes which use solar energy to convert carbon dioxide (CO2) and minerals into organic compounds and biomass. Eutrophication, rising CO2 concentrations and global warming are increasing Microcystis blooms globally. Due to its high availability and protein content, Microcystis biomass has been suggested as a protein source for animal feeds. This would reduce dependency on soybean and other agricultural crops and could make use of "waste" biomass when Microcystis scums and blooms are harvested. Besides proteins, Microcystis contain further nutrients including lipids, carbohydrates, vitamins and minerals. However, Microcystis produce cyanobacterial toxins, including microcystins (MCs) and other bioactive metabolites, which present health hazards. In this review, challenges of using Microcystis blooms in feeds are identified. First, nutritional and toxicological (nutri-toxicogical) data, including toxicity of Microcystis to mollusks, crustaceans, fish, amphibians, mammals and birds, is reviewed. Inclusion of Microcystis in diets caused greater mortality, lesser growth, cachexia, histopathological changes and oxidative stress in liver, kidney, gill, intestine and spleen of several fish species. Estimated daily intake (EDI) of MCs in muscle of fish fed Microcystis might exceed the provisional tolerable daily intake (TDI) for humans, 0.04 µg/kg body mass (bm)/day, as established by the World Health Organization (WHO), and is thus not safe. Muscle of fish fed M. aeruginosa is of low nutritional value and exhibits poor palatability/taste. Microcystis also causes hepatotoxicity, reproductive toxicity, cardiotoxicity, neurotoxicity and immunotoxicity to mollusks, crustaceans, amphibians, mammals and birds. Microbial pathogens can also occur in blooms of Microcystis. Thus, cyanotoxins/xenobiotics/pathogens in Microcystis biomass should be removed/degraded/inactivated sufficiently to assure safety for use of the biomass as a primary/main/supplemental ingredient in animal feed. As an ameliorative measure, antidotes/detoxicants can be used to avoid/reduce the toxic effects. Before using Microcystis in feed ingredients/supplements, further screening for health protection and cost control is required.

Cyanobacteria - insidious foe of the skin?

Cyanobacteria are ancient photosynthetic microorganisms that shaped today's atmosphere. Anthropocentric and irresponsible activities are changing the atmosphere which favor the frequent occurrence and mass development of cyanobacteria. Extensive cyanobacterial blooming causes numerous problems, including negative effects on human skin. Climate change, depletion of ozone layer, and the increased ultraviolet radiation also affect the skin and lead to more frequent occurrence of skin cancer. This research, for the first time, attempts to establish a connection between these two factors, or whether, in addition to ultraviolet radiation, cyanobacteria can influence the incidence of melanoma. With this objective in mind, an epidemiological investigation was conducted in Vojvodina, Serbia. It was observed that the incidence of melanoma was higher in municipalities where water bodies used for recreation, irrigation and fishing are blooming; however, results could be considered as inconclusive, because of the restrictions in the cancer database. Nevertheless, results gathered from the reviewed literature support the hypothesis that cyanobacteria could be a new potential risk factor for melanoma, while climate change could be a catalyst that converts these potential risk factors into cofactors, which act synergistically with the main risk factor - ultraviolet radiation - and induce an increase of melanoma incidence.

Elimination of cyanobacteria and microcystins in irrigation water-effects of hydrogen peroxide treatment.

Cyanobacterial blooms pose a risk to wild and domestic animals as well as humans due to the toxins they may produce. Humans may be subjected to cyanobacterial toxins through many routes, e.g., by consuming contaminated drinking water, fish, and crop plants or through recreational activities. In earlier studies, cyanobacterial cells have been shown to accumulate on leafy plants after spray irrigation with cyanobacteria-containing water, and microcystin (MC) has been detected in the plant root system after irrigation with MC-containing water. This paper reports a series of experiments where lysis of cyanobacteria in abstracted lake water was induced by the use of hydrogen peroxide and the fate of released MCs was followed. The hydrogen peroxide-treated water was then used for spray irrigation of cultivated spinach and possible toxin accumulation in the plants was monitored. The water abstracted from Lake Köyliönjärvi, SW Finland, contained fairly low concentrations of intracellular MC prior to the hydrogen peroxide treatment (0.04 µg L-1 in July to 2.4 µg L-1 in September 2014). Hydrogen peroxide at sufficient doses was able to lyse cyanobacteria efficiently but released MCs were still present even after the application of the highest hydrogen peroxide dose of 20 mg L-1. No traces of MC were detected in the spinach leaves. The viability of moving phytoplankton and zooplankton was also monitored after the application of hydrogen peroxide. Hydrogen peroxide at 10 mg L-1 or higher had a detrimental effect on the moving phytoplankton and zooplankton.

The Effect of a Combined Hydrogen Peroxide-MlrA Treatment on the Phytoplankton Community and Microcystin Concentrations in a Mesocosm Experiment in Lake Ludos.

Harmful cyanobacteria and their toxic metabolites constitute a big challenge for the production of safe drinking water. Microcystins (MC), chemically stable hepatotoxic heptapeptides, have often been involved in cyanobacterial poisoning incidents. A desirable solution for cyanobacterial management in lakes and ponds would eliminate both excess cyanobacteria and the MC that they potentially produce and release upon lysis. Hydrogen peroxide (H2O2) has recently been advocated as an efficient means of lysing cyanobacteria in lakes and ponds, however H2O2 (at least when used at typical concentrations) cannot degrade MC in environmental waters. Therefore, mesocosm experiments combining the cyanobacteria-lysing effect of H2O2 and the MC-degrading capacity of the enzyme MlrA were set up in the highly eutrophic Lake Ludos (Serbia). The H2O2 treatment decreased the abundance of the dominant cyanobacterial taxa Limnothrix sp., Aphanizomenon flos-aquae, and Planktothrix agardhii. The intracellular concentration of MC was reduced/eliminated by H2O2, yet the reduction of the extracellular MC could only be accomplished by supplementation with MlrA. However, as H2O2 was found to induce the expression of mcyB and mcyE genes, which are involved in MC biosynthesis, the use of H2O2 as a safe cyanobacteriocide still requires further investigation. In conclusion, the experiments showed that the combined use of H2O2 and MlrA is promising in the elimination of both excess cyanobacteria and their MC in environmental waters.

Global geographical and historical overview of cyanotoxin distribution and cyanobacterial poisonings.

Cyanobacteria are photoautotrophic organisms which occur in aquatic and terrestrial environments. They have the potential to produce toxins which pose a threat to human and animal health. This review covers the global distribution of the common cyanotoxins and related poisoning cases. A total of 468 selected articles on toxic cyanobacteria, dating from the earliest records until 2018, were reviewed. Most of the articles were published after 2000 (72%; 337 out of 468), which is consistent with the recent growth in interest in the analysis, toxinology and ecotoxicology of cyanotoxins. Animal and/or human poisoning cases were described in more than a third of the overall publications (38%; 177 out of 468). The reviewed publications showed that there were 1118 recorded identifications of major cyanotoxins in 869 freshwater ecosystems from 66 countries throughout the world. Microcystins were the most often recorded cyanotoxins worldwide (63%; 699 out of 1118), followed by cylindrospermopsin (10%; 107 out of 1118), anatoxins (9%; 100 out of 1118), and saxitoxins (8%; 93 out of 1118). Nodularins were the most rarely recorded cyanotoxins (2%; 19 out of 1118); however, there were also reports where cyanotoxins were not analysed or specified (9%; 100 out of 1118). The most commonly found toxic cyanobacterial genera were Microcystis spp. (669 reports), Anabaena spp. (397 reports), Aphanizomenon spp. (100 reports), Planktothrix spp. (98 reports), and Oscillatoria spp. (75 reports). Furthermore, there were 183 recorded cyanotoxin poisonings of humans and/or animals. Out of all toxic cyanobacterial blooms reviewed in this paper, the highest percentage of associated poisonings was found in North and Central America (39%; 69 cases out of 179), then Europe (20%; 35 out of 179), Australia including New Zealand (15%; 27 out of 179), and Africa (11%; 20 out of 179), while the lowest percentage was related to Asia (8%; 14 cases out of 179) and South America (8%; 14 cases out of 179). Events where only animals were known to have been affected were 63% (114 out of 182), whereas 32% (58 out of 182) of the investigated events involved only humans. A historical overview of human and animal poisoning episodes associated with cyanobacterial blooms is presented. Further, geographical data on the occurrence of cyanotoxins and related poisonings based on the available literature are shown. Some countries (mainly European) have done very intensive research on the occurrence of toxic cyanobacteria and cyanotoxins, and reported related ecotoxicological observations, while in some countries the lack of data is apparent. The true global extent of cyanotoxins and associated poisonings is likely to be greater than found in the available literature, and it can be assumed that ecotoxicological and hygienic problems caused by toxic cyanobacteria may occur in more environments.

Screening of cyanobacterial cultures originating from different environments for cyanotoxicity and cyanotoxins.

Eighty cultures from the Novi Sad Cyanobacterial Culture Collection (NSCCC) were screened for toxicity with Artemia salina bioassay and for common cyanobacterial toxins, microcystins/nodularin (MCs/NOD) and saxitoxin (STX), with ELISA assays. The results show that 22.5% (11) of the investigated cyanobacterial cultures in exponential phase exhibited toxicity in the A. salina bioassay and 38.7% (31) produced MCs/NOD and/or STX. However, the findings in the two methods applied were contradictory. Therefore, A. salina bioassay was repeated on 28 cultures in stationary growth phase, which were positive in ELISA assays but not in the initial A. salina bioassay. Seven more cultures exhibited cell-bound toxicity, and only one extracellular toxicity. The observed difference in the toxicity indicates that cyanobacterial growth phase could affect the screening results. The findings also varied depending on the environment from which the cultures originated. In the initial screening via bioassay, 11.8% (6 cultures out of 51) from terrestrial and 17.2% (5 out of 29) from aquatic environment showed cell-bound toxicity. Furthermore, based on the ELISA assay, 31.4% (16) of the cultures from terrestrial ecosystems were positive for the presence of the investigated cyanotoxins, and 51.7% (15) from aquatic ecosystems. Based on all results, more frequent toxin production was observed in cultures originating from aquatic environments. Furthermore, the group of terrestrial cultures that originated from biological loess crusts were basically non-toxic. The discrepancies in the results by two different methods indicates that the use of several complementary methods would help to improve the assessment of cyanobacterial toxicity and cyanotoxin analyses.

Cyanobacterial effects in Lake Ludos, Serbia - Is preservation of a degraded aquatic ecosystem justified?

Cyanobacteria are present in many aquatic ecosystems in Serbia. Lake Ludos, a wetland area of international significance and an important habitat for waterbirds, has become the subject of intense research interest because of practically continuous blooming of cyanobacteria. Analyses of water samples indicated a deterioration of ecological condition and water quality, and the presence of toxin-producing cyanobacteria (the most abundant Limnothrix redekei, Pseudanabaena limnetica, Planktothrix agardhii and Microcystis spp.). Furthermore, microcystins were detected in plants and animals from the lake: in macrophyte rhizomes (Phragmites communis, Typha latifolia and Nymphaea elegans), and in the muscle, intestines, kidneys, gonads and gills of fish (Carassius gibelio). Moreover, histopathological deleterious effects (liver, kidney, gills and intestines) and DNA damage (liver and gills) were observed in fish. A potential treatment for the reduction of cyanobacterial populations employing hydrogen peroxide was tested during this study. The treatment was not effective in laboratory tests although further in-lake trials are needed to make final conclusions about the applicability of the method. Based on our observations of the cyanobacterial populations and cyanotoxins in the water, as well as other aquatic organisms and, a survey of historical data on Lake Ludos, it can be concluded that the lake is continuously in a poor ecological state. Conservation of the lake in order to protect the waterbirds (without urgent control of eutrophication) actually endangers them and the rest of the biota in this wetland habitat, and possibly other ecosystems. Thus, urgent measures for restoration are required, so that the preservation of this Ramsar site would be meaningful.

Microcystin accumulation and potential effects on antioxidant capacity of leaves and fruits of Capsicum annuum.

Surface water, often used for irrigation purposes, may sometimes be contaminated with blooming cyanobacteria and thereby may contain their potent and harmful toxins. Cyanotoxins adversely affect many terrestrial plants, and accumulate in plant tissues that are subsequently ingested by humans. Studies were undertaken to (1) examine the bioaccumulation of microcystins (MCs) in leaves and fruits of pepper Capsicum annuum and (2) examine the potential effects of MCs on antioxidant capacity of these organs. Plants were irrigated with water containing MCs for a period of 3 mo. Data showed that MCs did not accumulate in leaves; however, in fruits the presence of the MC-LR (0.118 ng/mg dry weight) and dmMC-LR (0.077 ng/mg dry weight) was detected. The concentrations of MC-LR in fruit approached the acceptable guideline values and tolerable daily intake for this toxin. Lipid peroxidation levels and flavonoids content were significantly enhanced in both organs of treated plants, while total phenolic concentrations were not markedly variable between control and treated plants. Significant decrease in 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging capacity was noted for both organs. The levels of superoxide anion in fruits and hydroxyl radical in leaves were markedly reduced. Data suggest that exposure to MCs significantly reduced antioxidant capacity of experimental plants, indicating that MCs affected antioxidant systems in C. annuum.

Toxicology of microcystins with reference to cases of human intoxications and epidemiological investigations of exposures to cyanobacteria and cyanotoxins.

Blooms of cyanobacteria have been documented throughout history, all over the world. Mass populations of these organisms typically present hazards to human health and are known for the production of a wide range of highly toxic metabolites-cyanotoxins, of which among the most common and most investigated are the microcystins. The toxicity of the family of microcystin congeners to animal and cell models has received much attention; however, less is known about their negative effects on human health, whether via acute or chronic exposure. Useful information may be acquired through epidemiological studies since they can contribute to knowledge of the relationships between cyanotoxins and human health in environmental settings. The aim of this review is to compile and evaluate the available published reports and epidemiological investigations of human health incidents associated with exposure to mass populations of cyanobacteria from throughout the world and to identify the occurrence and likely role of microcystins in these events. After an initial screening of 134 publications, 42 publications (25 on the chronic and 17 on the acute effects of cyanotoxins) describing 33 cases of poisonings by cyanobacterial toxins in 11 countries were reviewed. The countries were Australia, China, Sri Lanka, Namibia, Serbia, Sweden, UK, Portugal, Brazil, USA, and Canada. At least 36 publications link cyanobacteria/cyanotoxins including microcystins to adverse human health effects. The studies were published between 1960 and 2016. Although the scattered epidemiological evidence does not provide a definitive conclusion, it can serve as additional information for the medical assessment of the role of microcystins in cancer development and other human health problems. This paper discusses the major cases of cyanotoxin poisonings as well as the strengths, weaknesses, and importance of the performed epidemiological research. This study also proposes some recommendations for future epidemiological work.

Tracing the influence of Mediterranean climate on Southeastern Europe during the past 350,000 years.

Loess-palaeosol sequences are valuable archives of past environmental changes. Although regional palaeoclimatic trends and conditions in Southeastern Europe have been inferred from loess sequences, large scale forcing mechanisms responsible for their formation have yet to be determined. Southeastern Europe is a climatically sensitive region, existing under the strong influence of both Mediterranean and continental climates. Establishment of the spatial and temporal evolution and interaction of these climatic areas is essential to understand the mechanisms of loess formation. Here we present high-resolution grain-size, environmental magnetic, spectrophotometric and geochemical data from the Stalac section in the Central Balkans (Serbia) for the past ~350,000 years. The goal of this study is to determine the influence of the Mediterranean climate during this period. Data show that the Central Balkans were under different atmospheric circulation regimes, especially during Marine Isotope Stages 9 and 7, while continental climate prevailed further north. We observe a general weakening of the Mediterranean climate influence with time. Our data suggest that Marine Isotope Stage 5 was the first interglacial in the Central Balkans that had continental climate characteristics. This prominent shift in climatic conditions resulted in unexpectedly warm and humid conditions during the last glacial.

Massive fish mortality and Cylindrospermopsis raciborskii bloom in Aleksandrovac Lake.

This paper presents a case study of a massive fish mortality during a Cylindrospermopsis raciborskii bloom in Aleksandrovac Lake, Serbia in mid-December 2012. According to a preliminary investigation of the samples taken on November 6 before the fish mortalities and to extended analyses of samples taken on November 15, no values of significant physicochemical parameters emerged to explain the cause(s) of the fish mortality. No industrial pollutants were apparent at this location, and results excluded the likelihood of bacterial infections. Even after freezing, the dissolved oxygen concentration in the water was sufficient for fish survival. High concentrations of chlorophyll a and phaeophytin occurred in the lake, and phytoplankton bloom samples were lethal in Artemia salina bioassays. A bloom of the cyanobacterium C. raciborskii was recorded during November. Although the A. salina bioassays indicated the presence of toxic compounds in the cyanobacterial cells, the cyanotoxins, microcystins, cylindrospermopsin and saxitoxin were not detected.