Geosmin Events Associated with Abundance Promoted by Nitrogen Supply in a Chinese Large Tropical Eutrophic Reservoir.

Taste and odor (T/O) compounds are a global threat in drinking water, mainly produced by cyanobacteria in freshwater environments. Temperature plays a crucial role in regulating geosmin dynamics in temperate and subtropical lakes, while its influence may be lower in tropical waters. To better understand the factors affecting geosmin occurrence in tropical waters, a dataset from a field investigation conducted in a large tropical reservoir was analyzed.

Coupling of cylindrospermopsin and pho-harboring Verrucomicrobia supports the formation of Raphidiopsis blooms in low-phosphorus waters.

Cylindrospermopsin (CYN) can induce phytoplankton community to secrete alkaline phosphatase (ALP), which is one of the important strategies for the bloom-forming cyanobacterium Raphidiopsis to thrive in extremely low-phosphorus (P) waters. However, how bacterioplankton community, another major contributor to ALPs in waters, couples to Raphidiopsis through CYN, and the role of this coupling in supporting the dominance of Raphidiopsis in nature remain largely unknown. Here, we conducted microcosm experiments to address this knowledge gap, using a combination of differential filtration-based and metagenomics-based methods to identify the sources of ALPs.

mitigated the negative effect of cylindrospermopsin-producing and non-cylindrospermopsin-producing on as a dietary supplement.

Feeding effects are crucial for evaluating the capacity of zooplankton to regulate phytoplankton populations within freshwater ecosystems. To examine the impact of the bloom-forming cyanobacteria , which occurs in tropical and subtropical freshwaters, on the growth of zooplankton in relation to toxins, filament length and fatty acid content, we fed with only (cylindrospermopsin (CYN)-producing and non-CYN-producing, as the negative controls), only (as the positive control) and a mixed diet containing (CYN-producing and non-CYN-producing) and . Consequently, our findings revealed that the toxic effect of CYN-producing strains on was mitigated by the coexistence of containing stearidonic acid (SDA, C18:4 ω3) in mixed diets.

Iron enrichment from hypoxic hypolimnion supports the blooming of Raphidiopsis raciborskii in a tropical reservoir.

Occurring worldwide, blooms of Raphidiopsis raciborskii threaten the use of water resources especially in tropical and subtropical waterbodies. Its high flexibility in the uses of light and macronutrients (C, N, P) frustrates any bloom prediction and control based on macronutrients regulation. To identify the critical factors promoting periodic blooms of R.

Cyanophycin accumulated under nitrogen-fluctuating and high-nitrogen conditions facilitates the persistent dominance and blooms of Raphidiopsis raciborskii in tropical waters.

Nutrient storage is considered a critical strategy for algal species to adapt to a fluctuating nutrient supply. Luxury phosphorus (P) uptake into storage of polyphosphate extends the duration of cyanobacterial dominance and their blooms under P deficiency. However, it is unclear whether nitrogen (N) storage in the form of cyanophycin supports persistent cyanobacterial dominance or blooms in the tropics where N deficiency commonly occurs in summer.

Nutrient Regulation of Relative Dominance of Cylindrospermopsin-Producing and Non-cylindrospermopsin-Producing .

Raphidiopsis raciborskii (previously ) can produce cylindrospermopsin (CYN) which is of great concern due to its considerable toxicity to human and animals. Its CYN-producing (toxic) and non-CYN-producing (non-toxic) strains co-exist commonly in natural water bodies, while how their relative dominance is regulated has not been addressed. In this study, we combined field investigation with laboratory experiments to assessed the relationship between toxic and non-toxic abundances under different nutrient levels.

Phosphorus deficiency stimulates dominance of Cylindrospermopsis through facilitating cylindrospermopsin-induced alkaline phosphatase secretion: Integrating field and laboratory-based evidences.

Potentially toxic Cylindrospermopsis raciborskii blooms are of emerging concerns, as its scale is spreading from tropical regions to high latitudes, increasing the risk of aquatic biota being exposed to cylindrospermopsin (CYN). So far, CYN-producing C. raciborskii strains have only been reported in tropical waters which are commonly phosphorus (P)-deficient, where they can dominate phytoplankton communities.

Interactive effect of water level and flushing rate on population dynamics of a harmful cyanobacterial species: Raphidiopsis raciborskii.

Changes in water level and flushing rate directly affect to a large extent the biomass of harmful cyanobacteria, and drive the shift of phytoplankton composition between cyanobacteria dominance/non-dominance in eutrophic waters. Here, we gave a theoretical formula describing the combinational effect of water level and flushing rate on cyanobacterial biomass in eutrophic and well-mixed waters. We also formulated an equation predicting the water level and flushing rate at which cyanobacteria become non-dominating in such water columns.

[Intraspecific Variation in Growth and Alkaline Phosphatase Activity of Strains in Response to Different Phosphorus Concentrations and Sources].

The cyanobacterial species are ubiquitous in tropical regions, and its successful invasion into temperate zones has been partially attributed to its ability of survival in low P availability and the existence of multiple ecotypes. To explore the physiological response of different strains to phosphorus fluctuations, four strains of isolated from the Zhenhai Reservoir were used to investigate their growth and alkaline phosphatase (ALP) activity at different inorganic phosphorus (Pi) concentrations (HP=7.13 mg ·L, MP=0.

Seasonal variation of microcystins and their accumulation in fish in two large shallow lakes of China.

Bioaccumulation of microcystins (MCs) has been widely observed in aquatic vertebrates and invertebrates, but its seasonal and specific variations remain unclear. In the present study, dissolved MCs in water, algal cell-bound MCs and muscle tissue MCs of nine fish species were investigated monthly in two of the largest shallow lakes in China: Lake Taihu and Lake Chaohu. The fish species were grouped as carnivorous, planktivorous, and omnivorous fish.

Do bigheaded carp act as a phosphorus source for phytoplankton in (sub)tropical Chinese reservoirs?

Stocking of bigheaded carp (mainly Hypophthalmichthys nobilis and H. molitrix) is commonly used in (sub)tropical Chinese reservoirs to control phytoplankton, but with ambiguous results. Whether these carp act as a phosphorus (P) source or sink for phytoplankton is debated.

Life-history responses of Daphnia sinensis simultaneously exposed to Microcystis aeruginosa and Cylindrospermopsis raciborskii.

Many cyanobacterial species co-occur commonly in a freshwater ecosystem and can be consumed simultaneously by zooplankton. Both Microcystis aeruginosa and Cylindrospermopsis raciborskii are the dominant species and coexist in eutrophic tropical waters, and they together are assumed to have exert a stronger effect on the life history traits of cladocerans than a single cyanobacterial species. In the present study, we tested the hypothesis with life-history experiments of Daphnia sienesis, a large cladoceran species in tropics.

Species diversity and seasonal dynamics of filamentous cyanobacteria in urban reservoirs for drinking water supply in tropical China.

Filamentous cyanobacteria have been observed to become the dominant species in reservoirs, especially in small reservoirs for drinking water supply in southern China. The occurrences of filamentous cyanobacteria blooms in such reservoirs add additional costs for water plants by decreasing the filtration efficiency and the potential of toxin production. To serve the purpose of drinking water supply, the effective risk assessment requires the dynamic pattern of filamentous cyanobacteria.

[Distribution and Factors Affecting in Guangdong Reservoirs].

originating from tropical and subtropical regions is potentially toxic and attracts much attention due to its extension to the global temperate zone in recent years. Based on historical data of 20 reservoirs with different trophic levels (dry season, wet season, and transitional season of 2010), this study focuses on the analysis of the occurrence and distribution of in the Guangdong Province. Based on the results, was found in 19 of the 20 reservoirs and its biomass ranges from 0.

Cyanobacterial removal by a red soil-based flocculant and its effect on zooplankton: an experiment with deep enclosures in a tropical reservoir in China.

As one kind of cheap, environmentally-friendly and efficient treatment materials for direct control of cyanobacterial blooms, modified clays have been widely concerned. The present study evaluated cyanobaterial removal by a red soil-based flocculant (RSBF) with a large enclosure experiment in a tropical mesotrophic reservoir, in which phytoplankton community was dominated by Microcystis spp. and Anabaena spp.

Development of Time-Resolved Fluoroimmunoassay for Detection of Cylindrospermopsin Using Its Novel Monoclonal Antibodies.

Cylindrospermopsin (CYN) is a cyanotoxin that is of particular concern for its potential toxicity to human and animal health and ecological consequences due to contamination of drinking water. The increasing emergence of CYN around the world has led to urgent development of rapid and high-throughput methods for its detection in water. In this study, a highly sensitive monoclonal antibody N8 was produced and characterized for CYN detection through the development of a direct competitive time-resolved fluorescence immunoassay (TRFIA).

Competition between toxic and non-toxic Microcystis aeruginosa and its ecological implication.

The frequency of toxic cyanobacterial blooms has increased in recent decades, but the factors that regulate the dominance of toxin-producing cyanobacteria over non-toxin-producing strains of one species are still obscure. This study examined the effects of temperature, light intensity, nitrate and phosphate on the dominance of MC-producing and non-MC-producing strains of Microcystis aeruginosa in monoculture and co-culture experiments. In the monoculture experiments, growth rates of the non-MC-producing strain were higher than those of the MC-producing strain under the same growth conditions.

Dual-labeled time-resolved immunofluorometric assay for the determination of IgM antibodies to rubella virus and cytomegalovirus in human serum.

Objectives: This study established a novel time-resolved fluorescence immunoassay (TRFIA) that allows the simultaneous determination of rubella virus (RV) IgM and cytomegalovirus (CMV) IgM in human serum.

Design And Methods: Lanthanum elements labeled antibody and streptavidin-biotin system were used in the "capture sandwich" format simultaneously.

Results: The working range of TRFIA for RV IgM was 2-80 AU/mL and for CMV IgM was 5-400 AU/mL.

Occurrence and dominance of Cylindrospermopsis raciborskii and dissolved cylindrospermopsin in urban reservoirs used for drinking water supply, South China.

The tropical cyanobacterium Cylindrospermopsis raciborskii is of particular concern for its invasive characteristics and production of the toxin cylindrospermopsin (CYN). The present study represents the first attempt to determine the distribution of C. raciborskii and CYN in tropical China.

Survivals of D. galeata in sub-tropical reservoirs: harmful effects of toxic cyanobacteria in food source.

In the present study, we tested the hypothesis that massive occurrence of cyanobacteria as food source is one of the factors limiting the distribution of the zooplankton Daphnia galeata in the warm water reservoirs of South China. D. galeata was fed with Chlorella pyrenoidosa, 4 strains of cyanobacteria (three strains of Microcystis aeruginosa: MC1, MC2 and MC3, and one strain of Pseudoanabaena sp.

[Usage of flocculation in emergent control of algal bloom in drinking water supplying reservoir].

An Anabaena circinalis bloom appeared in a reservoir for supplying drinking water in the south of China, in April 2006. Phytoplankton scums gathered and floated on the surface of the whole reservoir especially on the area of water intake, and the cell density of phytoplankton, cyanobacteria and Anabaena circinalis was as high as 7.3 x 10(7), 7.

[One step time-resolved fluorescence immunoassay for direct estimation of microcystins].

A direct-competitive time-resolved fluorescence immunoassay (TRFIA) for microcystin detection was established, which was based on europium labeled MCLR-BSA conjugant and microtiter plates coated with anti-mouse IgG. The optimal dilution of europium labeled MCLR-BSA conjugant is 1/50 and most appropriate titration of anti-microcystin-LR (MCLR) monoclonal antibodies is 100 ng/mL. The standard curve under the optimal conditions shows that the quantitative range is from approximately 0.

Structural and functional characterization of microcystin detoxification-related liver genes in a phytoplanktivorous fish, Nile tilapia (Oreochromis niloticus).

Liver genes related to phase I and phase II detoxification, as well as inhibition of reactive oxygen species (ROS) production, were cloned, and their response to microcystin-LR (MC-LR) and lipopolysaccharide (LPS) exposure via intraperitoneal injection, was determined in a phytoplanktivorous fish, Nile tilapia (Oreochromis niloticus). The cloned full-length cDNA of tilapia soluble glutathione S-transferase (sGST) was classified as alpha-class GST based on their amino acid sequence identity with other species. The tilapia sGST clone was 861 bp in length, and contained a 25 bp 5'-UTR, a 167 bp 3'-UTR and an open reading frame of 669 bp, encoding a polypeptide of 222 amino acids.

Molecular cloning and characterization of alpha-class glutathione S-transferase gene from the liver of silver carp, bighead carp, and other major Chinese freshwater fishes.

Two full-length cDNAs encoding glutathione S-transferase (GST) were cloned and sequenced from the hepatopancreas of planktivorous silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis). The silver carp and bighead carp GST cDNA were 920 and 978 bp in length, respectively, and both contained an open reading frame that encoding 223 amino acids. Partial GST cDNA sequences were also obtained from the liver of grass carp (Ctenopharyngodon idellus), crucian carp (Carassius auratu), mud carp (Cirrhinus molitorella), and tilapia (Oreochromis nilotica).

[Microcystin-LR induces apoptosis in L-02 cell line].

Objective: To investigate the toxicological mechanism of microcystin-LR (MCLR) on L-02 cells.

Methods: L-02 cells was treated with MCLR at different concentrations and the subsequent changes such as cell proliferation (MTT assay), morphology, lactate dehydrogenase (LDH) leakage, apoptosis rate and apoptosis-related gene expression were examined.

Results: MTT assay showed that MCLR mildly inhibited the cell growth within the initial 24 h of treatment but enhanced the cell viability after that till 60 h in a time- and dose-dependent manner.