The widespread occurrence of cyanobacteria blooms damages the water ecosystem and threatens the safety of potable water and human health. Exogenous L-lysine significantly inhibits the growth of a dominant cyanobacteria Microcystis aeruginosa in freshwater. However, the molecular mechanism of how lysine inhibits the growth of M. aeruginosa is unclear. In this study, both non-target and target metabolomic analysis were performed to investigate the effects of algicide L-lysine. The results showed that 8 mg L- 1 lysine most likely disrupts the metabolism of amino acids, especially the arginine and proline metabolism. According to targeted amino acid metabolomics analysis, only 3 amino acids (L-arginine, ornithine, and citrulline), which belong to the ornithine-ammonia cycle (OAC) in arginine metabolic pathway, showed elevated levels. The intracellular concentrations of ornithine, citrulline, and arginine increased by 115%, 124%, and 19.4%, respectively. These results indicate that L-lysine may affect arginine metabolism and OAC to inhibit the growth of M. aeruginosa.

• Keywords
• Arginine metabolism, L-lysine, Metabolomic analysis, Microcystin, Microcystis aeruginosa, Ornithine-ammonia cycle,
• MeSH
• Ammonia MeSH
• Arginine chemistry   metabolism   MeSH
• Citrulline metabolism   MeSH
• Ecosystem MeSH
• Herbicides * metabolism   MeSH
• Humans MeSH
• Lysine toxicity   metabolism   MeSH
• Microcystis * metabolism   MeSH
• Microcystins metabolism   MeSH
• Ornithine toxicity   metabolism   MeSH
• Cyanobacteria * metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Ammonia MeSH
• Arginine MeSH
• Citrulline MeSH
• Herbicides * MeSH
• Lysine MeSH
• Microcystins MeSH
• Ornithine MeSH

Planktothrix agardhii is one of the freshwater cyanobacteria that can produce the hepatotoxin microcystins (MC)-a real threat to human and animal health. Knowledge of the biological role of MC in producing organisms is highly desired to understand the driving force of MC production. Recently, emerging evidences have suggested that MC may have protective role in cells facing environmental stress. If this is true, one should expect differences in the cellular protective mechanisms between MC-containing and MC-deficient mutant strains. To test this hypothesis, it would be essential to investigate the consequences of the loss of MC in Planktothrix in the transcriptional responses of its heat shock proteins (Hsps) to abiotic stresses-an important component of cellular stress response. However, a crucial first step is prerequisite for the isolation of hsp genes here, as the genome of Planktothrix has not been fully published. Therefore, we have successfully isolated four hsp genes including clpC (hsp100), htpG (hsp90), groEL (hsp60), and groES (hsp10) from Planktothrix agardhii PCC 7805 using ramped annealing PCR (RAN-PCR) with consensus-degenerate hybrid oligonucleotide primers (CODEHOP) and annealing control primer (ACP) system. In addition, some putative regulatory sequences found in the upstream region of groESL operon of Planktothrix agardhii were also discussed.

• MeSH
• DNA, Bacterial chemistry   genetics   MeSH
• Stress, Physiological * MeSH
• Cloning, Molecular * MeSH
• Microcystins metabolism   MeSH
• Molecular Sequence Data MeSH
• Heat-Shock Proteins biosynthesis   genetics   MeSH
• Sequence Analysis, DNA MeSH
• Cyanobacteria genetics   metabolism   physiology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• DNA, Bacterial MeSH
• Microcystins MeSH
• Heat-Shock Proteins MeSH

Anthropogenic eutrophication of freshwater bodies increases the occurrence of toxic cyanobacterial blooms. The cyanobacterial toxin cylindrospermopsin (CYN) is detected in the environment with increasing frequency, driving the scientific effort to assess emerging health risks from CYN-producing blooms. Oral exposure to CYN results primarily in hepatotoxicity. Nevertheless, extrahepatic manifestations of CYN toxicity have been reported. Furthermore, cyanotoxins have been detected in aerosols and dust particles, suggesting potential toxic effects in the respiratory tract. To assess the susceptibility of airway epithelia towards cyanotoxins, monolayers of immortalized human bronchial epithelial cells HBE1 and 16HBE14o- were exposed to a concentration range of 0.1-10 μM CYN. Cytotoxic endpoints were assessed as morphologic alterations, resazurin reduction capacity, esterase activity, neutral red uptake, and by impedimetric real-time cell analysis. Depending on the endpoint assessed, EC50 values ranged between 0.7 and 1.8 μM (HBE1) and 1.6-4.8 μM (16HBE14o-). To evaluate alterations of other cellular events by subcytotoxic concentration of CYN (1 μM), phosphorylation of mitogen-activated protein kinases ERK and p38 was determined. Only a slight increase in p38 phosphorylation was induced by CYN in HBE1 cell line after 48 h, while activities of both ERK1/2 and p38 gradually and significantly increased in 16HBE14o- cells during 8-48 h exposure. This study suggests possible hazards of inhalation CYN exposures, which may severely impact the integrity of airway epithelia and epithelial cell signaling. Further research of CYN-induced toxicity and underlying mechanisms is needed, as well as more data on environmental concentrations of cyanotoxins in aerosols for exposure assessment.

• Keywords
• Cyanobacteria, Cyanotoxin, HBE, Inhalation toxicity, MAPK,
• MeSH
• Alkaloids MeSH
• Bacterial Toxins pharmacology   MeSH
• Cell Line MeSH
• Respiratory System cytology   MeSH
• Epithelial Cells drug effects   MeSH
• Eutrophication * MeSH
• Humans MeSH
• Microcystins pharmacology   MeSH
• Marine Toxins pharmacology   MeSH
• Cyanobacteria Toxins MeSH
• Uracil analogs & derivatives   pharmacology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Alkaloids MeSH
• Bacterial Toxins MeSH
• cylindrospermopsin MeSH Browser
• Microcystins MeSH
• Marine Toxins MeSH
• Cyanobacteria Toxins MeSH
• Uracil MeSH

Toxic cyanobacteria represent a serious health and ecological problem in drinking and recreational waters worldwide. Some previous toxicological studies investigated effects of isolated microcystins on laboratory rodents including mice and rats. However, much less attention has been paid to more realistic exposure situations such as the effects of MCs accumulated in food. The objectives of the present study were to provide a simple model simulation of the food chain in order to evaluate impacts of microcystins (MCs) on rat immune and haematologicalparameters. Impacts of feeding experimental rats with a diet containing fish meat with and without microcystins and complex toxic biomass have been studied during a 28 day exposure. Red blood cell parameters (RBC counts, haematocrit values, MCH, MCV and MCHC) showed significant differences in experimental groups (p ≤ 0.05, p ≤ 0.01) in comparison with the control group. We also detected an immunomodulatory effect in the experimental groups. NK cells and γδ+ T lymphocytes were significantly increased in peripheral blood in the group exposed to isolated microcystin in the food. Significant change in the ratio of CD4+ and CD8+ cells (increase of CD4+ and a drop in CD8+) was found in the group with added cyanobacterial biomass with low concentration of MCs. The greatest changes in lymphoid organs were observed in the same groups. There was an increase of spleen subpopulations of γδ+ T lymphocytes as well as of IgM+ lymphocytes (B lymphocytes) and CD8+ T lymphocytes. Indeed, the modulation of CD4+ and CD8+ of peripheral lymphocytes was associated with similar changes in thymic lymphocytic subpopulations. In summary, food containing fish meat with considerable doses of microcystins (or toxic cyanobacterial biomass) induces significant changes in RBC parameters and influence preferably innate part of the immune system represented by NK cells and by gamma-delta T cells, which are known to play role as a bridge between adaptive and innate immune response.

• Keywords
• Cyanobacteria, Immunomodulation, Lymphocyte subpopulations, Red blood cells, Wistar albino rats,
• MeSH
• Analysis of Variance MeSH
• Killer Cells, Natural immunology   MeSH
• Hematocrit MeSH
• Food Contamination MeSH
• Rats MeSH
• Microcystins administration & dosage   toxicity   MeSH
• Erythrocyte Count MeSH
• CD4-CD8 Ratio MeSH
• Rats, Wistar MeSH
• Immunity, Innate drug effects   MeSH
• Hemorheology drug effects   MeSH
• Cyanobacteria chemistry   MeSH
• Spleen cytology   drug effects   immunology   MeSH
• T-Lymphocytes immunology   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Microcystins MeSH

Changes in ecological and environmental factors lead to an increased occurrence of cyanobacterial water blooms, while secondary metabolites-producing cyanobacteria pose a threat to both environmental and human health. Apart from oral and dermal exposure, humans may be exposed via inhalation and/or swallowing of contaminated water and aerosols. Although many studies deal with liver toxicity, less information about the effects in the respiratory system is available. We investigated the effects of a prevalent cyanotoxin, microcystin-LR (MC-LR), using respiratory system-relevant human bronchial epithelial (HBE) cells. The expression of specific organic-anion-transporting polypeptides was evaluated, and the western blot analysis revealed the formation and accumulation of MC-LR protein adducts in exposed cells. However, MC-LR up to 20 μM neither caused significant cytotoxic effects according to multiple viability endpoints after 48-h exposure, nor reduced impedance (cell layer integrity) over 96 h. Time-dependent increase of putative MC-LR adducts with protein phosphatases was not associated with activation of mitogen-activated protein kinases ERK1/2 and p38 during 48-h exposure in HBE cells. Future studies addressing human health risks associated with inhalation of toxic cyanobacteria and cyanotoxins should focus on complex environmental samples of cyanobacterial blooms and alterations of additional non-cytotoxic endpoints while adopting more advanced in vitro models.

• Keywords
• 16HBE14o-, mitogen-activated protein kinase, HBE1, OATP, cytotoxicity, human bronchial epithelial cells, in vitro, microcystin-LR,
• MeSH
• Bronchi cytology   MeSH
• Cell Line MeSH
• Epithelial Cells drug effects   metabolism   MeSH
• Extracellular Signal-Regulated MAP Kinases metabolism   MeSH
• Humans MeSH
• Microcystins toxicity   MeSH
• p38 Mitogen-Activated Protein Kinases metabolism   MeSH
• Marine Toxins toxicity   MeSH
• Organic Anion Transporters genetics   MeSH
• Signal Transduction drug effects   MeSH
• Cell Survival drug effects   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• cyanoginosin LR MeSH Browser
• Extracellular Signal-Regulated MAP Kinases MeSH
• Microcystins MeSH
• p38 Mitogen-Activated Protein Kinases MeSH
• Marine Toxins MeSH
• Organic Anion Transporters MeSH

The aim of this study was to investigate the kinetics of accumulation and elimination of microcystins in the tissues of Nile tilapia (Oreochromis niloticus) and to evaluate the effect of cyanobacterial exposure on fish muscle quality (levels of total fat and ash, protein, dry matter and the composition of saturated, monounsaturated and polyunsaturated fatty acids). Fish were exposed for 28 days to a natural cyanobacterial bloom with total microcystin concentration around 1,200 μg g⁻¹ biomass dry weight. The hepatopancreas accumulated microcystins up to 350 ng g⁻¹ fresh weight, but concentrations in muscle were generally below the detection limit (2 ng g⁻¹ fresh weight). Following the exposure, fish were moved to the clean water, but only minor microcystin removal from the hepatopancreas was observed during a 4 week depuration period. Exposures of tilapia to the complex cyanobacterial bloom had only minor and temporary impacts on the investigated parameters of dietetic quality.

• MeSH
• Water Pollutants, Chemical pharmacokinetics   toxicity   MeSH
• Cichlids metabolism   MeSH
• Hepatopancreas chemistry   metabolism   MeSH
• Risk Assessment MeSH
• Food Contamination analysis   MeSH
• Animal Feed analysis   MeSH
• Microcystis chemistry   growth & development   MeSH
• Microcystins pharmacokinetics   toxicity   MeSH
• Harmful Algal Bloom MeSH
• Fresh Water chemistry   microbiology   MeSH
• Muscles chemistry   drug effects   MeSH
• Aquaculture MeSH
• Environmental Exposure analysis   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Water Pollutants, Chemical MeSH
• Microcystins MeSH