Co-reporter:Jun He;Guangyu Li;Jun Chen;Juan Lin;Cheng Zeng;Jing Chen
Archives of Toxicology 2017 Volume 91( Issue 1) pp:465-480
Publication Date(Web):16 March 2016
DOI:10.1007/s00204-016-1681-3
Microcystin-LR (MCLR), a cyanotoxin widely present in freshwater, has been shown to have potent acute hepatotoxicity. However, the chronic toxicity of low-dose MCLR remains confusing by traditional measurements of toxicity. This has impeded understanding of the chronic liver damage of low-dose MCLR and corresponding safety risks of the human exposure guideline value. Here, iTRAQ-based proteomics and NMR-based metabonomics were used to decipher the molecular toxicological signatures of low doses of MCLR in mice exposed to this agent for 90 days. Low levels of MCLR, even under the reported no observed adverse effect level, significantly altered hepatic protein expression, especially of proteins associated with lipid metabolism, transport, immune and proteolysis. Coherently, MCLR induced marked perturbations in lipid metabolites in both liver and serum. Integrated analysis of proteomic, metabolic, histological and cytokine profiles revealed that MCLR significantly inhibited fatty acid β-oxidation and hepatic lipoprotein secretion and promoted hepatic inflammation, resulting in nonalcoholic steatohepatitis disease (NASH). These findings for the first time provide compelling evidence that chronic exposure to low-level MCLR can induce NASH. These results also indicate that current guidelines for MCs in drinking water may be inadequate and associated with risks to human health.
Co-reporter:Liang ChenYufei Hu, Jun He, Jun Chen, John P. Giesy, Ping Xie
Environmental Science & Technology 2017 Volume 51(Issue 1) pp:
Publication Date(Web):December 5, 2016
DOI:10.1021/acs.est.6b03990
In this study, for the first time, changes in expressions of proteins and profiles of metabolites in liver of the small, freshwater fish Danio rerio (zebrafish) were investigated after long-term exposure to environmentally relevant concentrations of microcystin-LR (MC-LR). Male zebrafish were exposed via water to 1 or 10 μg MC-LR/L for 90 days, and iTRAQ-based proteomics and 1H NMR-based metabolomics were employed. Histopathological observations showed that MC-LR caused damage to liver, and the effects were more pronounced in fish exposed to 10 μg MC-LR/L. Metabolomic analysis also showed alterations of hepatic function, which included changes in a number of metabolic pathways, including small molecules involved in energy, glucose, lipids, and amino acids metabolism. Concentrations of lactate were significantly greater in individuals exposed to MC-LR than in unexposed controls. This indicated a shift toward anaerobic metabolism, which was confirmed by impaired respiration in mitochondria. Proteomics revealed that MC-LR significantly influenced multiple proteins, including those involved in folding of proteins and metabolism. Endoplasmic reticulum stress contributed to disturbance of metabolism of lipids in liver of zebrafish exposed to MC-LR. Identification of proteins and metabolites in liver of zebrafish responsive to MC-LR provides insights into mechanisms of chronic toxicity of MCs.
Co-reporter:Yun Li, Ping Xie, Jing Zhang, Min Tao, Xuwei Deng
Ecological Engineering 2017 Volume 99(Volume 99) pp:
Publication Date(Web):1 February 2017
DOI:10.1016/j.ecoleng.2016.11.040
•100 eastern plain lakes were surveyed to explore the effects of planktivorous fish and cyanobacteria on the zooplankton community.•Cyanobacteria had positive effects on Rotifera and small cladocera which led to the change of zooplankton community composition.•Filter-feeding planktivorous fish had positive effects on Rotifera and negative effects on Calanoida.•With the combined effects of planktivorous fish culture and eutrophication, r-strategy and good escape ability zooplankton dominated.To explore the changes of the zooplankton community in response to excessive interferences of anthropogenic eutrophication and aquaculture on aquatic ecosystem, we performed a survey to determine the variations in these communities in 100 eastern plain lakes of China in summer. Our results showed that when filter-feeding planktivorous fishes were in high yield, Rotifera and medium cladocera accounted for a large proportion of the community; when they were in low yield, small cladocera increased with the increased nutrient level. The detrended correspondence analysis demonstrated that planktivorous fish and cyanobacteria were important factors influencing the zooplankton community. The linear regression analysis showed that the fraction of Rotifera increased and Calanoida decreased with the increasing fish yield; the fraction of small cladocera increased with the increasing cyanobacteria. The results implied that zooplankton community succession was strengthened by the combined effects of planktivorous fish and cyanobacteria. The effects of filter-feeding planktivorous fish on zooplankton depend on the survival ability of different zooplankton species as well as the size. With the combined effects of planktivorous fish culture and eutrophication, the zooplankton community tend to be dominated by r-strategy species and good escape ability species.Download high-res image (175KB)Download full-size image
Co-reporter:Yufei Hu;Jun Chen;Huihui Fan
Environmental Science and Pollution Research 2016 Volume 23( Issue 8) pp:7211-7219
Publication Date(Web):2016 April
DOI:10.1007/s11356-016-6073-y
Cyanobacterial blooms-produced microcystins are secondary metabolites which can accumulate in the food chain and contaminate water, thus posing a potential threat to the health of aquatic animals and even humans. Microcystin toxicity affects not only the liver but also the other organs, i.e., the brain. The serious neurotoxicity effects caused by microcystins then lead to various symptoms. This review focuses on the neurotoxicity of microcystins. Microcystins can cross blood-brain barrier with the transport of Oatps/OATPs, causing neurostructural, functional, and behavioral changes. In this review, potential uptake mechanisms and neurotoxicity mechanisms are summarized, including neurotransmissions, neurochannels, signal transduction, oxidative stress, and cytoskeleton disruption. However, further researches are needed for detailed studies on signaling pathways and the downstream pathways of neurotoxicity of microcystins.
Co-reporter:Wenjing Wang, Yulei Zhang, Hong Shen, Ping Xie, Jia Yu
Biochemical Systematics and Ecology 2015 Volume 61() pp:62-66
Publication Date(Web):August 2015
DOI:10.1016/j.bse.2015.04.016
•Microcystis colonies disaggregate into single cells in laboratory cultures.•Changes in the associated bacterial community occur during colony disaggregation.•Certain extracellular compounds are only found in the colony form of Microcystis.•Associated bacteria clearly influence changes in Microcystis morphology.Microcystis is a well-studied type of bloom-forming genus cyanobacteria that occurs as colonies in lakes. However, whenever Microcystis colonies are transferred to the laboratory, they always disaggregate into a unicellular form. The mechanism underlying this disaggregation of Microcystis colonies remains uncharacterized. Here, we report on the changes in morphology and the changes in the composition of the associated bacterial community of Microcystis wesenbergii colonies. Denaturing gradient gel electrophoresis analysis (DGGE) showed that the diversity of the associated bacterial community decreased during the disaggregation of Microcystis colonies. Two γ-Proteobacteria and one Bacteroidetes species from the mucilage of Microcystis colonies were not detected following colony disaggregation, suggesting that these species may influence Microcystis colony morphology. Solid phase microextraction and gas chromatography–mass spectrometry (SPME GC/MS) analysis revealed that seven of the forty-one extracellular compounds detected were exclusively present in the media of the Microcystis colony extracts; these compounds may be secreted by bacteria and may be a beneficial role in Microcystis colony maintenance. The results of this study indicate that changes in the composition of the bacterial community associated with Microcystis colonies are likely responsible for the disaggregation of these colonies in the laboratory.
Co-reporter:Xiaochun Guo, Ping Xie, Jun Chen, Xun Tuo, Xuwei Deng, Shangchun Li, Dezhao Yu, Cheng Zeng
Journal of Chromatography B 2014 Volume 963() pp:54-61
Publication Date(Web):15 July 2014
DOI:10.1016/j.jchromb.2014.05.046
•Development of a LC/MS/MS method for the analysis of MC-LR and its GSH metabolites in rat liver.•Pretreatment conditions were optimized to extract analytes efficiently.•Combined use of SPE columns increases analyte purity when isolated from a complex matrix.•This method has been validated with excellent results.•Time- and dosage-effect studies were conducted using rat liver.The roles of glutathione (GSH) and cysteine (Cys) in the detoxification of Microcystin-LR (MC-LR) have recently become a popular area of research. However, lacking analysis methods for MC-LR-GSH and MC-LR-Cys (two main GSH pathway metabolites) in mammals, elucidation of the detoxification mechanism and metabolic pathway of MC-LR in mammals is difficult. In this study, a novel method for the simultaneous quantitative analysis of MC-LR, MC-LR-GSH and MC-LR-Cys in rat liver was developed and validated. The analytes were simultaneously extracted from rat liver using 3 M sodium chloride solution containing 0.01 M EDTA-Na2-5% acetic acid, followed by solid-phase extraction (SPE) on Oasis HLB and silica cartridges and determination by liquid chromatography–electrospray ionization mass spectrometry (LC–ESI–MS/MS). Under the optimized pretreatment conditions and instrument parameters, good recoveries of MC-LR, MC-LR-GSH and MC-LR-Cys were obtained at three concentrations (0.2, 1.0 and 2.5 μg g−1 dry weight (DW)) with values ranging from 97.7 ± 4.2 to 98.7 ± 5.1%, 70.1 ± 4.8 to 71.1 ± 4.1% and 79.8 ± 3.5 to 81.4 ± 4.0%, respectively. The relative standard deviations (RSDs) of these compounds at 0.2, 1.0 and 2.5 μg g−1 DW were between 4.3% and 6.9%. The limits of detection (LODs) were 0.005, 0.007 and 0.006 μg g−1 DW and the limits of quantification (LOQs) were 0.017, 0.023 and 0.020 μg g−1 DW for MC-LR, MC-LR-GSH and MC-LR-Cys, respectively. Furthermore, this method was successfully applied to both time- and dosage-effect studies of MC-LR, MC-LR-GSH and MC-LR-Cys in vivo.
Co-reporter:Dawen Zhang, Xuwei Deng, Ping Xie, Jun Chen, Longgen Guo
Food Chemistry 2013 Volume 140(1–2) pp:17-21
Publication Date(Web):1–15 September 2013
DOI:10.1016/j.foodchem.2013.01.124
Bioaccumulation and risk assessment of microcystins (MCs) in muscle of silver carp (Hypophthalmichthys molitrix) from eight eutrophic lakes along the Yangtze River of China were examined by using liquid chromatography electrospray ionisation mass spectrometry. MCs contents in seston collected from these eutrophic lakes ranged from 0.02 to 21.7 μg/L. MCs concentrations in silver carp muscle samples varied from 0.014 to 0.036 μg/g DW with an average of 0.028 μg/g DW. The total length of silver carp showed a significant negative correlation with MCs concentrations in their muscle (r = −0.85, p < 0.05), suggesting that MCs accumulation in silver carp muscle seems to be size dependent. EDI values of MCs in fish muscle from these eight eutrophic lakes varied from 0.0027 to 0.0071 μg/kg day, which was much lower than the TDI value of 0.04 μg/kg day previously established by WHO, indicating that it is safe to consume silver carp muscle from eutrophic lakes in China.Highlights► It is safe to consume the muscle of silver carp from eutrophic lakes. ► MCs accumulation in silver carp muscle seems to be size depended. ► MC-RR is the most prominent MCs in silver carp muscle.
Co-reporter:Xin Zhang;Xuezhen Zhang;Wenshan Zhou;Sujuan Zhao;Yanyan Zhao;Yan Cai
Journal of Applied Toxicology 2013 Volume 33( Issue 10) pp:1180-1186
Publication Date(Web):
DOI:10.1002/jat.2749
ABSTRACT
Microcystins (MCs) are highly liver-specific and evidenced as a liver tumor promoter. Oxidative stress is one of the most important toxicity mechanisms of MCs, which is tightly related to oxygen concentration. The effects of MCs on animals and cell lines in normoxia and the mechanisms have been well studied, but such effects in different oxygen conditions were still unclear. The aim of the present study was to explore the cellular response of the human hepatocellular carcinoma cell line (HepG2) to MC-LR exposure under hypoxic (1% O2) and normoxic (21% O2) conditions. We examined cell viability, mitochondrial membrane potential (MMP), superoxide dismutase (SOD) activity and gene expression posttoxin exposure. Cell viability was increased by MC-LR in normoxia although decreased in hypoxia. MC-LR markedly induced MMP loss under hypoxic condition but only slightly MMP loss under normoxic condition. SOD activity was significantly induced by MC-LR in hypoxia, indicating prolonged oxidative stress. Inhibitory apoptosis protein (c-IAP2) was significantly up-regulated by MC-LR under normoxic condition, suggesting that c-IAP2 played an important role in the promotion of cell proliferation by MC-LR. These results indicate that MC-LR promotes cell proliferation under normoxic condition whereas induces cell apoptosis under hypoxic condition. Copyright © 2012 John Wiley & Sons, Ltd.
Co-reporter:Wei Zhang;Gaodao Liang;Laiyan Wu;Xun Tuo;Wenjing Wang;Jun Chen
Ecotoxicology 2013 Volume 22( Issue 6) pp:1012-1019
Publication Date(Web):2013 August
DOI:10.1007/s10646-013-1086-5
To elucidate the interspecies variation of susceptibility to microcystins (MCs), fresh plasma and purified albumin from six kinds of mammals and fish were used in toxins-substances binding test. Protein contents in the test plasma were analyzed and the binding characteristics to MCs were compared. Two kinds of widely observed MCs, microcystin-LR (MC-LR) and microcystin-RR (MC-RR) were tested and data were collected through the method of equilibrium dialysis. It was found that total plasma protein and albumin content in mammals were nearly two times and four times higher than that in fish, respectively. In the test range of 0–100 μg/mL, binding rates of fish plasma to MCs were considered significant lower (p < 0.01) than that of mammals. And human plasma demonstrated the highest binding rate in mammals. In all the test species, plasma protein binding rates of MC-RR were significantly higher than MC-LR (p < 0.01). Besides, binding profiles of albumin were acquired under the protein content of 0.67 mg/mL. Human serum albumin demonstrated the highest affinity to MCs throughout the six species and differences among the other five species were considered not significant (p > 0.05). From the view of protein binding, it is concluded that both the variation of plasma protein composition and albumin binding characteristic could influence the existing form of MCs in circulation, change MCs utilization, alter MCs half-life and further contribute to the difference of susceptibility between mammals and fish.
Co-reporter:Huan Zhang;Gongguo Wu;Huan Zhang;Jun Xu;Qiong Zhou
Hydrobiologia 2013 Volume 703( Issue 1) pp:247-256
Publication Date(Web):2013 February
DOI:10.1007/s10750-012-1370-z
Seasonal water-level changes in floodplain lakes can induce variations in primary and secondary production, thus affecting trophic interactions. In this study, we tested the latter by studying size- and temporal hydrology-related shifts in the diet of shortjaw tapertail anchovy Coilia brachygnathus (Actinopterygii, Engraulidae) from Lake Poyang. During the wet season, δ13C values ranged from −28.2‰ for small anchovies to −24.6‰ for larger individuals, but δ15N ranged from 18.9‰ for smaller fish to 12.4‰ for larger fish. Significant 13C-enrichment and 15N-depletion occurred with increasing size, revealing that different carbon sources were used as the fish grew. Given the high hydrologic fluctuation levels, significant differences in δ13C values were observed among larger anchovies between seasons, indicating a temporal dietary shift. Anchovies fed primarily on shrimp and fish during the low-water season despite the predominance of zooplankton during the two seasons studied, which indicated increased piscivorous reliance. C. brachygnathus exhibited higher δ15N values during the wet season because the food items were 15N-enriched. Human waste brought by floods could be another possible interpretation. Considering C. brachygnathus is an important link between plankton production and higher piscivorous trophic levels, changes in the species are expected to affect the functioning of lake food webs along the trophic pathway.
Co-reporter:Huiying Li;Yan Cai;Guangyu Li
Archives of Environmental Contamination and Toxicology 2013 Volume 65( Issue 3) pp:537-545
Publication Date(Web):2013 October
DOI:10.1007/s00244-013-9910-8
Microcystin-LR (MCLR) is a widespread cyanotoxin and has immunotoxicity to animals, including fish. Chemokines are considered to play important roles in inflammatory response induced by MCLR. In this study, we cloned the full-length cDNA of interleukin-8 (IL-8) from bighead carp (Aristichthys nobilis) for the first time. The full-length IL-8 cDNA was 552 bp and contained a 297-bp open-reading frame that encoded for a 98-amino acid protein. The deduced IL-8 protein had a typical aspartic acid (D)-leucine (L)-arginine (R) and a CXC motif at the N-terminal, which were conserved in most fish species. Phylogenetic analysis showed that bighead carp IL-8 protein was grouped in the teleost IL-8 lineage 2. Under normal conditions, the expression of IL-8 is constitutive and weak in all tested tissues. However, MCLR treatment could significantly increase the transcription of IL-8 in bighead carp in a temporal- and dose-dependent pattern. The present study will help us to understand more about the evolution of IL-8 and its function in the MCLR induced proinflammatory response in bighead carp.
Co-reporter:Yanyan Zhao, Ping Xie, and Huihui Fan
Environmental Science & Technology 2012 Volume 46(Issue 1) pp:34-41
Publication Date(Web):September 1, 2011
DOI:10.1021/es201514h
Studies have demonstrated that microcystins (MCs) can act as potential carcinogens and have caused serious risk to public environmental health. The molecular mechanisms of MC-induced susceptibility to carcinogenesis are largely unknown. In this study, we performed for the first time a comprehensive analysis of changes in microRNAs (miRNAs) and proteins expression in livers of mice treated with MC-LR. Utilizing microarray and two-dimensional gel electrophoresis (2-DE) analysis, we identified 37 miRNAs and 42 proteins significantly altered. Many aberrantly expressed miRNAs were related to various cancers (e.g., miR-125b, hepatocellular carcinoma; miR-21, leukemia; miR-16, chronic lymphocytic leukemia; miR-192, pituitary adenomas; miR-199a-3p, ovarian cancer; miR-34a, pancreatic cancer). Several miRNAs (e.g., miR-34a, miR-21) and proteins (e.g., TGM2, NDRG2) that play crucial roles in liver tumorigenesis were first found to be affected by MC-LR in mouse liver. MC-LR also altered the expression of a number of miRNAs and proteins involved in several pathways related to tumorigenesis, such as glutathione metabolism, VEGF signaling, and MAPK signaling pathway. Integration of post-transcriptomics, proteomics, and transcriptomics reveals that the networks miRNAs and their potential target genes and proteins involved in had a close association with carcinogenesis. These results provide an early molecular mechanism for liver tumorigenesis induced by MCs.
Co-reporter:Xuwei Deng, Ping Xie, Min Qi, Gaodao Liang, Jun Chen, Zhimei Ma, Yan Jiang
Journal of Chromatography A 2012 Volume 1219() pp:75-82
Publication Date(Web):6 January 2012
DOI:10.1016/j.chroma.2011.11.031
Off-flavors are among the most troublesome compounds in the environment worldwide. The lack of a viable theory for studying the sources, distribution, and effect of odors has necessitated the accurate measurement of odors from environmental compartments. A rapid and flexible microwave-assisted purge-and-trap extraction device for simultaneously determining five predominant odors, namely, dimethyltrisulfide, 2-methylisoborneol, geosmin, β-cyclocitral and β-ionone, from the primary sources and sinks is demonstrated. This instrument facilitates the extraction and concentration of odors from quite different matrices simultaneously. This device is a solvent-free automated system that does not require cleaning and is timesaving. The calibration curves of the five odor compounds showed good linearity in the range of 1–500 ng/L, with correlation coefficients above 0.999 (levels = 7) and with residuals ranging from approximately 77% to 104%. The limits of detection (S/N = 3) were below 0.15 ng/L in algae sample and 0.07 ng/g in sediment and fish tissue samples. The relative standard deviations were between 2.65% and 7.29% (n = 6). Thus the proposed design is ready for rapid translation into a standard analytical tool and is useful for multiple applications in the analysis of off-flavors.Highlights► In this study, a new online instrument was developed for the determination of odors. ► This instrument is an automated solvent free system and requires no clean-up step. ► Extraction and concentration of odors can be performed simultaneously. ► A method was developed by using the instrument for the analysis of odors from environment matrices. ► This method has been validated with excellent results.
Co-reporter:Jun He, Jun Chen, Laiyan Wu, Guangyu Li, and Ping Xie
Journal of Proteome Research 2012 Volume 11(Issue 12) pp:5934-5946
Publication Date(Web):2017-2-22
DOI:10.1021/pr300685g
Microcystin-LR (MCLR), a potent hepatotoxin, is causing increased risks to public health. Although the liver is the main target organ of MCLR, the metabolic profiling of liver in response to MCLR in vivo remains unknown. Here, we comprehensively analyzed the metabolic change of liver and ileal flushes in rat orally gavaged with MCLR by 1H nuclear magnetic resonance (NMR). Quantification of hepatic MCLR and its glutathione and cysteine conjugates by liquid chromatography–electrospray ionization–mass spectrometry (LC-ESI-MS) was conducted. Metabonomics results revealed significant associations of MCLR-induced disruption of hepatic metabolisms with inhibition of nutrient absorption, as evidenced by a severe decrease of 12 amino acids in the liver and their corresponding elevation in ileal flushes. The hepatic metabolism signature of MCLR was characterized by significant inhibition of tyrosine anabolism and catabolism, three disrupted pathways of choline metabolism, glutathione exhaustion, and disturbed nucleotide synthesis. Notably, substantial alterations of hepatic metabolism were observable even at the low MCLR-treated group (0.04 mg/kg MCLR), although no apparent histological changes in liver were observed in the low- and medium-dosed groups. These observations offered novel insights into the microcystin hepatotoxic mechanism at a functional level, thereby facilitating further assessment and clarification of human health risk from MCs exposure.
Co-reporter:Peili Wang;Hong Shen
Microbial Ecology 2012 Volume 63( Issue 2) pp:369-382
Publication Date(Web):2012 February
DOI:10.1007/s00248-011-9917-5
Diatom blooms occur in many water bodies worldwide, causing significant ecological and social concerns. In order to understand the mechanisms of diatom blooms formation, the effects of varying phosphorus (P) concentration and hydrodynamics on the growth of diatoms were studied by combining results from field observations and laboratory experiments. The field investigation showed that spring diatom blooms (Cyclotella meneghiniana and Stephanodiscus hantzschii) occurred in Lake Taihu and Hanjiang River with similar environmental factors such as water temperature, pH, and dissolved oxygen in 2008. Concentrations of total phosphorus (TP), total nitrogen, and ammonia nitrogen (NH4-N) in Lake Taihu were significantly higher than the concentrations in the Hanjiang River. Laboratory experiments were conducted to evaluate growth and physiological responses of four lotic diatoms (Cyclotella atomus, Fragilaria crotonensis, Nitzschia palea, and S. hantzschii, isolated from the Hanjiang River) and three lentic diatoms (C. meneghiniana, Melosira varians, and Stephanodiscus minutulus, isolated from Lake Taihu, Lake Donghu, and Guanqiao Pond, respectively) to various P concentrations under small-scale turbulent and standing conditions. Our results showed that, with turbulence, lotic diatoms C. atomus, F. crotonensis, N. palea, and S. hantzschii demonstrated a significant increase in affinity for P compared with lentic diatoms C. meneghiniana, M. varians, and S. minutulus. Moreover, lotic diatoms C. atomus, F. crotonensis, and N. palea had higher growth rates and photosynthetic efficiencies with small-scale turbulence than with standing conditions both in P-limited and P-replete conditions. Lotic species S. hantzschii and three lentic diatoms (C. meneghiniana, M. varians, and S. minutulus) grew well under standing conditions. Our results may explain our field observation that the occurrence of diatom blooms in lakes is often associated with higher TP concentrations whereas in rivers, diatom blooms occur at a wide range of TP concentrations under flows. Therefore, different hydrodynamics and nutrient concentrations determined the dominant diatom species, according to their habitat-dependent physiological characteristics.
Co-reporter:Xuwei Deng, Gaodao Liang, Jun Chen, Min Qi, Ping Xie
Journal of Chromatography A 2011 Volume 1218(Issue 24) pp:3791-3798
Publication Date(Web):17 June 2011
DOI:10.1016/j.chroma.2011.04.041
Production and fate of taste and odor (T&O) compounds in natural waters are a pressing environmental issue. Simultaneous determination of these complex compounds (covering a wide range of boiling points) has been difficult. A simple and sensitive method for the determination of eight malodors products of cyanobacterial blooms was developed using automatic purge and trap (P&T) coupled with gas chromatography–mass spectrometry (GC–MS). This extraction and concentration technique is solvent-free. Dimethylsulfide (DMS), dimethyltrisulfide (DMTS), 2-isopropyl-3-methoxypyrazine (IPMP), 2-isobutyl-3-methoxypyrazine (IBMP), 2-methylisoborneol (MIB), β-cyclocitral, geosmin (GSM) and β-ionone were separated within 15.3 min. P&T uses trap #07 and high-purity nitrogen purge gas. The calibration curves of the eight odors show good linearity in the range of 1–500 ng/L with a correlation coefficient above 0.999 (levels = 8) and with residuals ranging from approximately 83% to 124%. The limits of detection (LOD) (S/N = 3) are all below 1.5 ng/L that of GSM is even lower at 0.08 ng/L. The relative standard deviations (RSD) are between 3.38% and 8.59% (n = 5) and recoveries of the analytes from water samples of a eutrophic lake are between 80.54% and 114.91%. This method could be widely employed for monitoring these eight odors in natural waters.
Co-reporter:Xuezhen Zhang;Wei Ji;Huan Zhang;Wei Zhang
Journal of Applied Toxicology 2011 Volume 31( Issue 6) pp:561-567
Publication Date(Web):
DOI:10.1002/jat.1597
Abstract
It is well known that fish have stronger tolerance than mammals to microcystin (MC) exposure, and such a difference is attributed to their different core body temperatures. However, no in vivo study has been conducted to investigate the effects of temperature on MC-induced toxicity in fish, a typical poikilotherm. Tolerance and detoxification response of zebrafish treated with MC-LR were investigated under three temperatures. The LD50 values evidently increased with a decline of the temperature (547, 260 and 176 µg kg−1 at 12, 22 and 32 °C, respectively), indicating stronger tolerance of the fish at lower temperatures. Changes in the transcription of glutathione S-transferase (GST) isoforms in the fish were observed, and their sensitivity of response in the transcription of GST mRNA was on the order of 12 > 32 > 22°C. We screened out several GST genes which were more delicate to solve the MC-LR exposure at different temperatures, i.e. GST rho1, al, p1 and theta1 in the 12 °C group, and GST zeta1 and p2 in the 22 and 32 °C groups. Our findings partly validate the hypothesis that high temperature enhances toxic effects of MCs on poikilotherms. Our studies also indicate that temperature-dependent toxic effects should be taken into account for field toxic assessment of microcystins in fish. Copyright © 2010 John Wiley & Sons, Ltd.
Co-reporter:Jun Xu;Qiang Yang;Meng Zhang;Min Zhang;Lars-Anders Hansson
Aquatic Ecology 2011 Volume 45( Issue 4) pp:483-492
Publication Date(Web):2011 November
DOI:10.1007/s10452-011-9369-5
Stable isotope analysis provides a powerful tool for describing the energetic pathways in a variety of ecosystems. However, isotope ratios of animal tissues can be altered by preservation methods, potentially leading to biased estimates of energy pathways when they are not taken into account. Here, we investigated the direct preservation effects of formalin, ethanol, NaCl, and drying on the δ13C and δ15N of fish muscle tissues, as well as the ultimate effects on the reconstruction of the energy pathways. All preservation methods, except drying, had significant impacts on δ13C and δ15N values. The effects of preservation appear to be highly taxa-specific and no significant time-dependent variations in nearly 2-year duration of preservation. δ13C and δ15N values were generally changed dramatically within the early stage of the preservation process and became stable over a relatively long-term preservation. Using an isotopic balance mixing model, the isotope-based food web reconstruction reveals that, without preservation correction, the importance of the pelagic energetic pathways for the fishes could be misestimated, except for the drying preservation. These results highlight that preservation can bias the interpretation of food web reconstruction results.
Co-reporter:Nichun Guo
Aquatic Ecology 2011 Volume 45( Issue 1) pp:63-73
Publication Date(Web):2011 March
DOI:10.1007/s10452-010-9324-x
The adverse influences of insufficient food and toxins on Daphnia carinata’s body growth, reproduction and tolerance were investigated in the laboratory. Different concentrations of Scendesmusobliquus and a mixture of S. obliquus and microcystin (MC)-containing Microcystis aeruginosa PCC7820 were used to feed D. carinata. Glutathione S-transferase (GST) activity towards five chemical compounds (substrates) was measured and used as an indicator of their tolerance. Body growth rate and clutch size of D. carinata decreased with declined concentration or decreased proportion of S. obliquus in the diet. GST activity decreased with ageing in D. carinata. However, GST activity to several chemical compounds increased when food quantity or food quality decreased. Adult D. carinata had a lower GST activity towards p-nitrophenenzyl chloride (PNBC) than juveniles and exhibited a sharp decline (P < 0.001) in GST activity towards PNBC as the animals aged. It is suggested that the age-specific decrease in GST activity is a possible mechanism for the high morality of adult D. carinata in the summer of eutrophic lakes.
Co-reporter:Laiyan Wu, Ping Xie, Jun Chen, Dawen Zhang, Gaodao Liang
Journal of Chromatography A 2010 Volume 1217(Issue 9) pp:1455-1462
Publication Date(Web):26 February 2010
DOI:10.1016/j.chroma.2009.12.068
A novel method for identification and quantification of microcystin-RR (MC-RR) and its metabolites (MC-RR-GSH and MC-RR-Cys) in the fish liver was developed and validated. These analytes were simultaneously extracted from fish liver using water containing EDTA with 5% acetic acid, followed by a mixed-mode cation-exchange SPE (Oasis MCX) and subsequently determined by liquid chromatography–electrospray ionization ion trap mass spectrometry (LC–ESI-ITMS). Extraction parameters including volume and pH of eluting solvents, were optimized. Best recoveries were obtained by using 10 mL of 15% ammonia solution in methanol. The mean recoveries at three concentrations (0.2, 1.0, and 5.0 μg g−1 dry weight [DW]) for MC-RR, MC-RR-GSH and MC-RR-Cys were 93.6–99%, 68.1–73.6% and 90.0–95.2%, respectively. Method detection limit (MDL) were 4, 7 and 5 ng g−1 DW for MC-RR, MC-RR-GSH and MC-RR-Cys, respectively. Limits of quantification (LOQs) for MC-RR, MC-RR-GSH and MC-RR-Cys were calculated to be 10, 18 and 13 ng g−1 DW, respectively. Finally, this method was successfully applied to the identification and quantification of MC-RR, MC-RR-GSH and MC-RR-Cys in the liver of bighead carp with acute exposure of MCs.
Co-reporter:Guangyu Li;Huiying Li;Jun Chen;Le Hao ;Qian Xiong
Journal of Biochemical and Molecular Toxicology 2010 Volume 24( Issue 4) pp:250-259
Publication Date(Web):
DOI:10.1002/jbt.20333
Abstract
The expression of glutathione S-transferase (GST) is a crucial factor in determining the sensitivity of cells and organs in response to a variety of toxicants. In this study, we cloned the core nucleotide of alpha, kappa, mu, mGST, pi, rho, and theta-like GST genes from bighead carp (Aristichthys nobilis). Their derived amino acid sequences were clustered with other vertebrate GSTs in a phylogenetic tree, and the bighead carp GST sequences have the highest similarity with those from common carp and zebrafish. We quantified the constitutive mRNA transcription of GST isoforms in eight different tissues (liver, kidney, spleen, intestine, muscle, heart, brain, and gill). The information obtained from the present study could be distilled into a few generalized principles: multiple GST isoenzymes were ubiquitously expressed in all tissues; majority of GSTs had high constitutive expression in intestine, liver, and kidney. These findings are in agreement with the roles of these tissues in xenobiotic metabolism. At the same time, some unique findings were detected in the current experiment: (1) higher expression of most GSTs was observed in spleen; (2) the expression of GST pi was highest in almost all the studied tissues except muscle; the other two isoforms, GST alpha and rho, were also highly expressed in liver, kidney, intestine, spleen, heart, and brain of bighead carp. All these results strongly imply an important role of these GST isoforms in detoxification of ingested xenobiotics. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:250–259, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.20333
Co-reporter:Qian Xiong;Huiying Li;Le Hao;Guangyu Li;Tong Qiu;Ying Liu
Journal of Biochemical and Molecular Toxicology 2010 Volume 24( Issue 6) pp:361-367
Publication Date(Web):
DOI:10.1002/jbt.20347
Abstract
Microcystins (MCs) induce the production of reactive oxygen species (ROS) in various tissues in mammals, whereas the endogenous antioxidant enzymes are responsible to scavenge the ROS. ROS can modulate the antioxidant enzyme activities by regulating the mRNA levels. The present study was undertaken to find out the relationship between the transcriptional alterations of antioxidant enzymes and MCs stimulation in rats. The time-dependent changes of relative transcription abundance of catalase (CAT), Mn-superoxide dismutase (Mn-SOD), Cu,Zn-superoxide dismutase (Cu,Zn-SOD), glutathione reductase (GR), glutathione peroxidase (GPx), and gamma-glutamylcysteine synthetase (γ-GCS) were investigated in three organs (liver, kidney, and testis) of male Wistar rats injected intravenously (i.v.) with 80 μg MC-LRequivalent/kg body weight using the quantitative real-time PCR (qPCR) method. We found that MCs could affect the transcriptional activities of these antioxidant enzymes in liver, kidney, and testis of MCs-treated rats and we speculated the possible causation of the transcriptional change. The altered transcription of antioxidant enzymes may play an important role in counteracting the potential deleterious effects of elevated oxidative stress induced by MCs, and this will provide us new insights into the possible role of antioxidant enzymes in the toxicological mechanisms of MCs at molecular level. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:361–367, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.20347
Co-reporter:Li Li;Longgen Guo
Fish Physiology and Biochemistry 2010 Volume 36( Issue 2) pp:165-172
Publication Date(Web):2010 June
DOI:10.1007/s10695-008-9228-z
The worldwide occurrence of cyanobacterial blooms makes it necessary to perform environmental risk assessment procedures to monitor the effects of microcystins (MCs) on fish. Oxidative stress biomarkers are valuable tools in this regard. In the present study, phytoplanktivorous bighead carp (Aristichthys nobilis) were injected intraperitoneally (i.p.) with extracted MCs (mainly MC-RR and -LR) at two doses, 400 and 1,000 μg kg−1 bw, and antioxidant responses of the liver as biomarkers of oxygen-mediated toxicity were studied at 1, 3, 12, 24 and 48 h after injection. Contents of reactive oxygen species (ROS) and activities of antioxidant enzymes [catalase (CAT), superoxide dismutase (SOD), glutathione peroxide (GPX), and glutathione reductase (GR)] as well as glutathione S-transferase (GST) in the liver in both dose groups showed a biphasic change with an increase at initial 3 h followed by a decrease after injection, owing to the roles of the antioxidant system in eliminating excessive ROS and regenerating glutathione (GSH). The increased GST was probably due to the high transcription of cytosolic GST α and ρ, suggesting the importance of MCs detoxification by GSH pathway. The stable GSH levels in liver may be explained by the high basic GSH concentration in liver, and/or an increased GSH synthesis, suggesting a high ability to detoxify MCs and to release associated high oxidative pressure in phytoplantivorous fish.
Co-reporter:Dawen Zhang;Jun Chen
Bulletin of Environmental Contamination and Toxicology 2010 Volume 84( Issue 2) pp:202-207
Publication Date(Web):2010 February
DOI:10.1007/s00128-009-9910-6
In this study, bighead carp treated with two doses, i.e. 400 and 580 μg MC-LReq (Microcystin-LR equivalent)/kg bw. After dosing bighead carp with 400 and 580 ug MC-LReq/Kg bw, the mean concentrations of microcystins (MCs) was significantly higher in boiled muscle than unboiled controls. These results indicate that the potential threat of microcystins contaminated fish to humans has been underestimated. The increase in microcystins occurs by the release of phosphatase-bound microcystins by boiling.
Co-reporter:Zhourui Wen;Jun Xu
Environmental Monitoring and Assessment 2010 Volume 163( Issue 1-4) pp:139-147
Publication Date(Web):2010 April
DOI:10.1007/s10661-009-0823-y
Stable nitrogen isotope ratios of five mussel species from littoral and pelagic areas were investigated with different trophic states in the eutrophic Lake Taihu, the third largest lake in China. Interpopulation variability for these mussels was relatively small in foot tissues because of the slow turnover time. Seasonal and spatial variations among the δ15N values of mussels might be due in part to the natural variation in δ15N values of potential food sources and the variation in the amount of human pollutions discharged into various locations of the lake. Although the increase of mussel δ15N values was accompanied by the increase of nutrient concentrations in most situations in this study, statistically significant correlations were only 22% of the total correlations in this survey, which might be attributed to the different time-scale variations in nutrient concentrations and isotope signatures and the unknown details of the trophic pathways and metabolism for incorporation of these nutrients.
Co-reporter:X. Zhang;P. Xie;D. Li;R. Tang;H. Lei
Bulletin of Environmental Contamination and Toxicology 2009 Volume 82( Issue 5) pp:574-578
Publication Date(Web):2009 May
DOI:10.1007/s00128-009-9671-2
This study was conducted to investigate time-dependent changes in oxidative enzymes in liver of crucian carp after intraperitoneally injection with extracted microcystins 600 and 150 μg kg−1 body weight. The results showed that activities of antioxidant enzymes, including superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase generally exhibited a rapid increase in early phase (1–3 h post injection), but gradually decreased afterwards (12–48 h) compared with the control, with an evident time-dependent effect. These zigzag changes over time contributed a better understanding on oxidative stress caused by microcystins in fish.
Co-reporter:Ting Yu;Ming Dai;Gaodao Liang
Bulletin of Environmental Contamination and Toxicology 2009 Volume 83( Issue 5) pp:
Publication Date(Web):2009 November
DOI:10.1007/s00128-009-9805-6
A liquid chromatography electrospray mass spectrometry (LC/ESI/MS) method working in multiple reactions monitoring mode for the determination of trace amounts of microcystin variants (MC-LR and [Dha7] MC-LR) in waters was developed. The limit of quantification was 0.05 μg/L and the limit of detection was 0.015 μg/L for MC-LR and [Dha7] MC-LR, respectively. Recoveries for MCs were in the range of 68%–81%. MC-LR and [Dha7] MC-LR were chemically stable with similar physiochemical behavior.
Co-reporter:Ying Liu;Xiao-Ping Wu
Limnology 2009 Volume 10( Issue 1) pp:1-5
Publication Date(Web):2009 April
DOI:10.1007/s10201-008-0255-3
To explore the potential grazing effects of mussels on Microcystis aeruginosa, a common bloom-forming phytoplankton, Unio douglasiae and Corbicula fluminea were fed with Scenedesmus obliquus, toxic and non-toxic strains of Microcystis aeruginosa as single food and as mixtures in the laboratory. When fed with single foods, U. douglasiae has similar clearance rates on the three algae populations, while C. fluminea has significantly lower clearance rate on toxic M. aeruginosa than those on the other two algae populations. When fed with mixture foods, both the mussels show significantly higher clearance rates than on single foods. The clearance rates of U. douglasiae on the different food mixtures are not significantly different, and C. fluminea has a significantly lower clearance rate on the toxic food mixtures than that on non-toxic food mixtures. Although the relative lower clearance rates of C. fluminea on toxic food, we may still deduce that both the mussels can exert grazing pressure on phytoplankton. The deduction is supported by the composition of the excretion products. The excretion products (faeces and pseudofaeces) of both mussels contained mainly S. obliquus. In both mixed-food treatments, the ratios of S. obliquus to M. aeruginosa in the excrete products are significantly higher than those in the foods. Therefore, it can be concluded that both mussels prefer M. aeruginosa to S. obliquus, and can cause grazing pressure on M. aeruginosa.
Co-reporter:Daogui Deng;Qiong Zhou;Hua Yang;Longgen Guo;Hong Geng
Limnology 2008 Volume 9( Issue 1) pp:1-11
Publication Date(Web):2008 April
DOI:10.1007/s10201-007-0229-x
Field and experimental studies were conducted to evaluate the combined impacts of cyanobacterial blooms and small algae on seasonal and long-term changes in the abundance and community structure of crustacean zooplankton in a large, eutrophic, Chinese lake, Lake Chaohu. Seasonal changes of the crustacean zooplankton from 22 sampling stations were investigated during September 2002 and August 2003, and 23 species belonging to 20 genera were recorded. Daphnia spp. dominated in spring but disappeared in mid-summer, while Bosmina coregoni and Ceriodaphnia cornuta dominated in summer and autumn. Both maximum cladoceran density (310 ind. l−1) and biomass (5.2 mg l−1) appeared in autumn. Limnoithona sinensis, Sinocalanus dorrii and Schmackeria inopinus were the main species of copepods. Microcystis spp. were the dominant phytoplankton species and formed dense blooms in the warm seasons. In the laboratory, inhibitory effects of small colonial Microcystis on growth and reproduction of Daphnia carinata were more remarkable than those of large ones, and population size of D. carinata was negatively correlated with density of fresh large colonial Microcystis within a density range of 0–100 mg l−1 (r = −0.82, P< 0.05). Both field and experimental results suggested that seasonal and long-term changes in the community structure of crustacean zooplankton in the lake were shaped by cyanobacterial blooms and biomass of the small algae, respectively, i.e., colonial and filamentous cyanobacteria contributed to the summer replacement of dominant crustacean zooplankton from large Daphnia spp. to small B. coregoni and C. cornuta, while increased small algae might be responsible for the increased abundance of crustacean zooplankton during the past decades.
Co-reporter:S. Wu;S. Wang;H. Yang;P. Xie;L. Ni
Bulletin of Environmental Contamination and Toxicology 2008 Volume 80( Issue 4) pp:329-334
Publication Date(Web):2008 April
DOI:10.1007/s00128-008-9378-9
Microcystin (MC) problem made more and more care about in China, intercellular MC (Int-MC) and cellular MC (Cel-MC) were important contents to reflect the producing-MC ability by cyanobacteria and by lakes. To study the correlations between Int-MC, Cel-MC concentration and biological and environmental factors, eight cyanobacterial blooming lakes were studied in the middle and lower reaches of the Yangtze River. Microcystin-RR (MC-RR) and Microcystin-LR (MC-LR) were the primary toxin variants in our data. From the linear correlations between MC and environmental factors, cellular-YR had significant correlation with most of chemical factors except total nitrogen (TN) and the ratio of total nitrogen and total phosphorus (TN/TP), most intracellular MC analogues had significant correlations with total dissolved nitrogen (TDN), ammonium (NH4+), nitrite (NO2–), TP, total dissolved phosphorus (TDP), Microcystis. From the canonal correspondence analysis, Int-MC concentrations were closely related with the chemical and biological factors, such as TP, total organic carbon (TOC), chlorophyll a (Chl a), Microcystis biomass, et al. While Cel-MC contents, especially Cel-RR and Cel-LR, were closely related with light environmental in the lakes such as water depth and transparence.
Co-reporter:Xuezhen Zhang;Weimin Wang;Dapeng Li
Fish Physiology and Biochemistry 2008 Volume 34( Issue 4) pp:323-329
Publication Date(Web):2008 December
DOI:10.1007/s10695-007-9191-0
Healthy crucian carp (Carassius auratus) were treated by intraperitoneal (i.p.) injection of crude cyanobacterial extracts at two doses, 50 and 200 μg MC-LR equiv kg−1 BW. High mortality (100%) was observed within 60 h post injection in the high-dose group. In the treated fish, activities of four plasma enzymes, alanine aminotransferase (ALT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH), all showed substantial increases, with both dose and time-dependent effects. These increases of enzyme activity indicate severe impairment occurred in the liver of crucian carp over time. Plasma concentrations of energy-related biomolecules including glucose (GLU), cholesterol (CHO), triglyceride (TG), and total protein (TP) showed marked changes in the high-dose group, possibly a nutritional imbalance correlated with the liver injury caused by intraperitoneal exposure to crude cyanobacterial extracts.
Co-reporter:Jun Xu;Min Zhang
Hydrobiologia 2008 Volume 605( Issue 1) pp:45-54
Publication Date(Web):2008 June
DOI:10.1007/s10750-008-9299-y
Trophic patterns of omnivorous freshwater shrimps, Exopalaemon modestus and Macrobrachium nipponensis, were investigated in two shallow eutrophic lakes by using stable isotope analysis. δ15N and δ13C of M. nipponensis and E. modestus increased with increasing body weight, which might be attributed to larger individuals ingesting organisms that feed higher up the food chain and/or increased assimilation of benthic food items with enriched isotopic signatures. Of the freshwater shrimps occurring in the studied lakes, those from Lake Taihu had significantly elevated δ15N and δ13C values (4.3‰ and 1.8‰, respectively) compared with those from the less eutrophic Lake Chaohu, indicating that the isotopic signature might partially reflect the trophic states of their habitats. Mixing model results suggested that the benthic food web provides the primary carbon source for both shrimp species, and that E. modestus assimilated relatively more pelagic food sources than M. nipponensis in these lakes.
Co-reporter:Hong Geng
Ecotoxicology 2008 Volume 17( Issue 8) pp:709-715
Publication Date(Web):2008 November
DOI:10.1007/s10646-008-0219-8
Blooms of Microcystis aeruginosa frequently occur in many eutrophic lakes in China, however, there is very little experimental study on the relationship between Microcystis and rotifers from Chinese waters. The effects of different concentrations of toxic M. aeruginosa PCC7820 on two common freshwater rotifers Brachionus calyciflorus and B. rubens were investigated in laboratory experiments. B. calyciflorus was able to utilize this strain of M. aeruginosa as a food source. However, M. aeruginosa suppressed the survival and reproduction of B. calyciflorus at the highest concentration (106 cells/ml) probably due to the inadequate nutrition. B. rubens was inhibited by toxic M. aeruginosa PCC7820 and the inhibition increased with the increasing Microcystis concentration. Our study indicates that the two rotifers have different sensitivities to toxic M. aeruginosa and that toxic cyanobacteria may affect zooplankton community structure by differentially inhibiting the different zooplankton taxa.
Co-reporter:Ming Dai;Jun Chen;Gaodao Liang;Ying Liu;Tong Qiu
Chromatographia 2008 Volume 68( Issue 9-10) pp:
Publication Date(Web):2008 November
DOI:10.1365/s10337-008-0777-1
A rapid and sensitive method was developed and validated for the determination of MCYST (microcystin)-RR, -LR, and [Dha7] MCYST-LR in rat plasma by liquid chromatography-tandem mass spectrometry. The analytes were extracted from rat plasma by protein precipitation, followed by solid-phase extraction. Liquid chromatography with electrospray ionization mass spectrometry, operating in selected reaction monitoring (SRM) mode, was used to quantify MCYST-RR, -LR, and [Dha7] MCYST-LR in rat plasma. The recoveries for each analyte in rat plasma ranged from 70.8 to 88.7%. The calibration curve was linear within the range from 0.005 to 1.25 μg mL−1. The limit of detection were 1.4, 1.0, 0.6 ng mL−1 for MCYST-RR, -LR, and [Dha7] MCYST-LR. The overall precision was determined on three different days. The values for within- and between-day precision in rat plasma were within 15%. This method was applied to the identification and quantification of microcystins in rat plasma with acute exposure of microcystins via intravenous injection.
Co-reporter:Zhixin Ke;Longgen Guo
Hydrobiologia 2008 Volume 607( Issue 1) pp:41-49
Publication Date(Web):2008 July
DOI:10.1007/s10750-008-9365-5
The spring–summer successions of phytoplankton and crustacean zooplankton were examined weekly in Meiliang Bay of the subtropical Lake Taihu in 2004 and 2005. During the study period, the ecosystem of Meiliang Bay was characterized by (i) clearly declined nitrogen compounds (nitrate, TN, and ammonium) and slowly increased phosphorus compounds (TP and SRP), (ii) increased total phytoplankton density and rapid replacement of chlorophyta (mainly Ulothrix) by cyanobacteria (mainly Microcystis), and (iii) rapid replacement of large-sized crustaceans (Daphnia and Moina) by small-sized ones (Bosmina, Limnoithona, and Ceriodaphnia). Results from the CCA and correlation analysis indicate that the spring-summer phytoplankton succession was primarily controlled by abiotic factors. Cyanobacteria were mainly promoted by increased temperature and decreased concentrations of nitrogen compounds. The pure contribution of crustacean was low for the variation of phytoplankton suggesting a weak top-down control by crustacean zooplankton in the subtropical Lake Taihu.
Co-reporter:Jingxian Wang
Environmental Geochemistry and Health 2007 Volume 29( Issue 5) pp:375-383
Publication Date(Web):2007/10/01
DOI:10.1007/s10653-007-9081-5
The aim of this study was to examine the effects of chemical nonylphenols (NPs) on the antioxidant system of Microcystis aeruginosa strains. The degradation and sorption of NPs by M. aeruginosa were also evaluated. High concentrations of NPs (1 and 2 mg/l) were found to cause increases in superoxidase dismutase (SOD) and glutathione-S-transferase (GST) activities and in glutathione (GSH) levels. These results suggest that toxic stress manifested by elevated SOD and GST levels and GSH contents may be responsible for the toxicity of NPs to M. aeruginosa and that the algal cells could improve their antioxidant and detoxification ability through the enhancement of enzymatic and nonenzymatic prevention substances. The observed elevations in GSH levels and GST activities were relatively higher than those in SOD activities, indicating that GSH and GST contributed more in eliminating toxic effects than SOD. Low concentrations of NPs (0.05–0.2 mg/l) enhanced cell growth and decreased GST activity in algal cells of M. aeruginosa, suggesting that NPs may have acted as a protecting factor, such as an antioxidant. The larger portion of the NPs (>60%) disappeared after 12 days of incubation, indicating the strong ability of M. aeruginosa to degrade the moderate persistent NP compounds. The sorption ratio of M. aeruginosa after a 12-day exposure to low nominal concentrations of NPs (0.02–0.5 mg/l) was relatively high (>30%). The fact that M. aeruginosa effectively resisted the toxic effects of NPs and strongly degraded these pollutants indicate that M. aeruginosa cells have a strong ability to adapt to variations in environmental conditions and that low and moderate concentrations of organic compounds may favor its survival. Further studies are needed to provide detailed information on the fate of persistent organic pollutants and the survival of algae and to determine the possible role of organic pollutants in the occurrence of water blooms in eutrophic lakes.
Co-reporter:Songbo Wang;Shikai Wu;Haijun Wang
Hydrobiologia 2007 Volume 575( Issue 1) pp:203-209
Publication Date(Web):2007 January
DOI:10.1007/s10750-006-0394-7
Crustacean zooplankton size structure in 27 aquaculture lakes was studied to test the hypothesis that larger size structure is associated with higher grazing pressure. Mean body length of crustaceans was positively correlated with increasing Chl a (r2 = 0.40, P = 0.000) and TP (r2 = 0.38, P = 0.000), contrary to the empirical studies. However, the ratio of zooplankton to phytoplankton biomass decreased significantly with increasing TP (r2 = 0.27, P = 0.005) and mean body length (r2 = 0.46, P = 0.000). Meanwhile, size structure showed no significant effect in explaining residual variations of phosphorus–chlorophyll relationship (P = 0.231). These results indicate that larger size structure was not always associated with higher zooplankton grazing pressure. It is likely that in aquaculture lakes crustacean zooplankton size structure was of minor importance in control of phytoplankton biomass, and it was mainly regulated by fish predation. The results showed in our study and the empirical studies might be a reflection of two different stages of lake eutrophication and fish predation intensity.
Co-reporter:S. Li;P. Xie;J. Xu;L. Li;G. Liang
Bulletin of Environmental Contamination and Toxicology 2007 Volume 79( Issue 3) pp:297-300
Publication Date(Web):2007 September
DOI:10.1007/s00128-007-9207-6
Co-reporter:S. Li;P. Xie;J. Xu;X. Zhang;J. Qin
Bulletin of Environmental Contamination and Toxicology 2007 Volume 78( Issue 3-4) pp:226-230
Publication Date(Web):2007 April
DOI:10.1007/s00128-007-9116-8
Co-reporter:L. Zhang;X. Zang;J. Xu;P. Xie;Z. Zhu
Bulletin of Environmental Contamination and Toxicology 2007 Volume 78( Issue 3-4) pp:262-264
Publication Date(Web):2007 April
DOI:10.1007/s00128-007-9117-7
Co-reporter:Jun Xu;Min Zhang;Qiong Zhou
Bulletin of Environmental Contamination and Toxicology 2007 Volume 79( Issue 3) pp:323-326
Publication Date(Web):2007 September
DOI:10.1007/s00128-007-9198-3
We investigated differences in δ15N of seston and icefishes from seven freshwater ecosystems with different trophic states in China. An increase of seston δ15N values was accompanied by an increase of total nitrogen and phosphorus concentrations. Significantly positive correlations were observed between δ15N of icefishes and δ15N of seston, total nitrogen and phosphorus concentrations. This study demonstrated that icefishes could be preferred indicators of anthropogenic contamination in test systems because they integrated waste inputs over long time periods and reflected the movement of waste through the pelagic food chain.
Co-reporter:Muqi Xu, Hong Cao, Ping Xie, Daogui Deng, Weisong Feng and Jian Xu
Environmental Science: Nano 2005 vol. 7(Issue 7) pp:670-674
Publication Date(Web):14 Jun 2005
DOI:10.1039/B504396B
Structural and functional parameters of protozoan communities colonizing on PFU (polyurethane foam unit) artificial substrate were assessed as indicators of water quality in the Chaohu Lake, a large, shallow and highly polluted freshwater lake in China. Protozoan communities were sampled 1, 3, 6, 9 and 14 days after exposure of PFU artificial substrate in the lake during October 2003. Four study stations with the different water quality gradient changes along the lake were distinguishable in terms of differences in the community’s structural (species richness, individual abundance, etc.) and functional parameters (protozoan colonization rates on PFU). The concentrations of TP, TN, COD and BOD as the main chemical indicators of pollution at the four sampling sites were also obtained each year during 2002–2003 for comparison with biological parameters. The results showed that the species richness and PFU colonization rate decreased as pollution intensity increased and that the Margalef diversity index values calculated at four sampling sites also related to water quality. The three functional parameters based on the PFU colonization process, that is, Seq, G and T90%, were strongly related to the pollution status of the water. The number of protozoan species colonizing on PFU after exposure of 1 to 3 days was found to give a clear comparative indication of the water quality at the four sampling stations. The research provides further evidence that the protozoan community may be utilized effectively in the assessment of water quality and that the PFU method furnishes rapid, cost-effective and reliable information that may be useful for measuring responses to pollution stress in aquatic ecosystems.
Co-reporter:Ping Xie;Yiyu Chen
Science 2001 Vol 294(5544) pp:999-1000
Publication Date(Web):02 Nov 2001
DOI:10.1126/science.294.5544.999c
Co-reporter:Qing Wang, Ping Xie, Jun Chen, Gaodao Liang
Toxicon (November 2008) Volume 52(Issue 6) pp:721-727
Publication Date(Web):1 November 2008
DOI:10.1016/j.toxicon.2008.08.004
The distribution of microcystins (MCs) in various tissues of Wistar rats was studied under laboratory conditions. Rats were injected intravenously (i.v.) with extracted MCs at a dose of 80 μg MC-LRequivalent/kg body weight. MCs concentrations in various tissues were detected at 1, 2, 4, 6, 12 and 24 h post-injection using liquid chromatography–mass spectrometry (LC–MS). The highest concentration of MCs was found in kidney (0.034–0.295 μg/g dry weight), followed by lung (0.007–0.067 μg/g dry weight), stomach (0.010–0.058 μg/g dry weight) and liver (0.003–0.052 μg/g dry weight). The maximum MCs content in the whole body of rat, 2.9% of the injected dose, was observed at 2 h post-injection. MCs concentration was higher in kidney than in liver during the experiment, and two peaks of MCs concentration (at 2 and 24 h, respectively) were observed in kidney, indicating that MCs can be excreted directly via kidney of rat. Though heart, intestine, spleen, brain, gonad and stomach contained less than 0.2% of injected MCs during the whole experiment stage, the presence of MCs in these tissues represents potential damage to them.
Co-reporter:Huiying Li, Ping Xie, Dawen Zhang, Jun Chen
Toxicon (May 2009) Volume 53(Issue 6) pp:595-601
Publication Date(Web):1 May 2009
DOI:10.1016/j.toxicon.2008.11.005
Microcystins are heptapeptide toxins produced by cyanobacteria. Microcystin-RR (MC-RR) is a common variant among the 80 variants identified so far. There have been many investigations documenting the toxic effects of microcystins on animals and higher plants, but little is known on the toxic effects of microcystins on algae, especially at molecular level. We studied the effects of MC-RR on gene expression profile of a few antioxidant enzymes and heat shock protein-70 (Hsp70) in Synechocystis sp. PCC6803. After two days post-exposure, a high dose toxin (5 mg/l, about 4.8 × 10−3 mM) significantly increased expression levels of the genes gpx1, sodB, katG, acnB, γ-TMT and dnaK2, while a relatively low dose toxin (1 mg/l, about 9.63 × 10−4 mM) induced a moderate and slow increase of gene expression. Our results indicate that MC-RR could induce the oxidative stress in Synechocystis sp. PCC6803 and the increase in gene expression of antioxidant enzymes and Hsp70 might protect the organism from the oxidative damage. In addition, cell aggregation was observed during the early period of exposure, which might be a specific oxidative stress reaction to MC-RR.
Co-reporter:Dapeng Li, Ping Xie, Xuezhen Zhang, Yanyan Zhao
Toxicon (May 2009) Volume 53(Issue 6) pp:638-644
Publication Date(Web):1 May 2009
DOI:10.1016/j.toxicon.2009.01.027
Circulatory responses of crucian carp injected intraperitoneally with extracted microcystins (MCs) were studied at sublethal and lethal doses (150 and 600 μg MC kg−1 body mass, respectively). Mean arterial blood pressure (MAP), heart rate, hematocrit (Hct), red blood cell (RBC) counts, and circulating blood volume (BV) were assayed at 0, 1, 3, 12, 24, and 48 h post-toxin administration. MAP decreased significantly in a dose-dependent manner over time. Within the 48-h test period, the lethal dose as well as the sublethal dose resulted in a steady decline of MAP without recovery. Heart rate significantly increased within 24 h post-injection as blood pressure significantly dropped, then showed a terminal decline to the control level. The dose-dependent decreases in BV and Hct were directly related to the drop in MAP. Intraperitoneal injection of a lethal dose of MCs led to hepatic and gill hemorrhage. Consequently, crucian carp given MCs suffered from hypovolemic hypotensive shock.
Co-reporter:Qian Xiong, Ping Xie, Huiying Li, Le Hao, Guangyu Li, Tong Qiu, Ying Liu
Toxicon (July 2009) Volume 54(Issue 1) pp:1-7
Publication Date(Web):1 July 2009
DOI:10.1016/j.toxicon.2009.01.035
Previous studies have shown that gonads were the second target organ of microcystins (MCs), and that MCs exposure exerted obvious toxic effects on male reproductive system of mammals. However, relevant molecular evidences are still lacking. Fas-signaling pathway plays a key role in toxicant-induced germ cell apoptosis. This study was to evaluate the responses of Fas/FasL system related genes and proteins in testes of rats injected intravenously with MCs. Enhanced apoptosis of germ cells in the testes of MCs-treated rats was detected by the terminal deoxynucleotidyl transferase-mediated deoxy-UTP nick end labeling (TUNEL) associated with up-regulation of the Fas/FasL system. Both Fas and FasL protein expression were induced evidently from 1 h post-injection, and this high expression level maintained throughout the experiment. In addition, the activation of caspase-8 and caspase-3 protein was also observed, which were indicators of apoptosis. These results suggested the likely involvement of Fas/FasL system in the MCs-induced germ cell apoptosis. It is also suggested that MCs can cause damage to Sertoli cells directly.
Co-reporter:Huiying Li, Ping Xie, Guangyu Li, Le Hao, Qian Xiong
Toxicon (January 2009) Volume 53(Issue 1) pp:169-175
Publication Date(Web):1 January 2009
DOI:10.1016/j.toxicon.2008.10.027
Microcystins (MCs) are a potent liver tumor promoter, possessing potent tumor-promoting activity and weak initiating activity. Proto-oncogenes are known to be involved in the tumor-promoting mechanisms of microcystin-LR. However, few data are available on the effects of MCs on proto-oncogenes in the whole animal. To investigate the effects of MCs on the expression profile of the proto-oncogenes in different organs, male Wistar rats were injected intravenously with microcystin extracts at a dose of 86.7 μg MC-LR eq/kg bw (MC-LR eq, MC-LR equivalents). mRNA levels of three proto-oncogenes c-fos, c-jun and c-myc in liver, kidney and testis were analyzed using quantitative real-time PCR at several time points post-injection. Significant induction of these genes at transcriptional level was observed in the three organs. In addition, the increase of mRNA expression of all three genes was much higher in liver than in kidney and testis. Meanwhile, the protein levels of c-Fos and c-Jun were investigated by western blotting. Both proteins were induced in the three organs. However, elevations of protein levels were much lower than those of mRNA levels. These findings suggest that the expression of c-fos, c-jun and c-myc might be one possible mechanism for the tumor-promoting activity and initiating activity of microcystins.
Co-reporter:Jingxian Wang, Ping Xie, Nichun Guo
Environmental Research (January 2007) Volume 103(Issue 1) pp:70-78
Publication Date(Web):1 January 2007
DOI:10.1016/j.envres.2006.05.013
Both organic pollution and eutrophication are prominent environmental issues concerning water pollution in the world. It is important to reveal the effects of organic pollutants on algal growth and toxin production for assessing ecological risk of organic pollution. Since nonylphenol (NP) is a kind of persistent organic pollutant with endocrine disruptive effect which exists ubiquitously in environments, NP was selected as test compound in our study to study the relationship between NP stress and Microcystis growth and microcystin production. Our study showed that responses of toxic and nontoxic Microcystis aeruginosa to NP stress were obviously different. The growth inhibition test with NP on M. aeruginosa yielded effect concentrations EbC50 values within this range of 0.67–2.96 mg/L. The nontoxic M.aeruginosa strains were more resistant to NP than toxic strains at concentration above 1 mg/L. Cell growth was enhanced by 0.02–0.2 mg/L NP for both toxic and nontoxic strains, suggesting a hormesis effect of NP on M. aeruginosa. Both toxic and nontoxic strains tended to be smaller with increasing NP. But with the increased duration of the experiment, both the cell size and the growth rate began to resume, suggesting a quick adaptation of M. aeruginosa to adverse stress. NP of 0.05–0.5 mg/L significantly promoted microcystin production of toxic strain PCC7820, suggesting that NP might affect microcystin production of some toxic M. aeruginosa in the field. Our study showed that microcystin excretion was species specific that up to 75% of microcystins in PCC7820 were released into solution, whereas >99% of microcystins in 562 remained in algal cells after 12 days’ incubation. NP also significantly influenced microcystin release into cultural media. The fact that NP enhanced growth and toxin production of M. aeruginosa at low concentrations of 0.02–0.5 mg/L that might be possibly found in natural freshwaters implies that low concentration of NP may favor survival of M. aeruginosa in the field and may play a subtle role in affecting cyanobacterial blooms and microcystin production in natural waters.
Co-reporter:Songbo Wang, Ping Xie, Hong Geng
Limnologica - Ecology and Management of Inland Waters (February 2010) Volume 40(Issue 1) pp:1-7
Publication Date(Web):1 February 2010
DOI:10.1016/j.limno.2009.03.001
The planktonic community of freshwater Rotifera in 27 subtropical lakes was studied to assess the relative importance of physicochemical factors and crustacean zooplankton as determinants of rotifer density and species distribution. Factor analysis and multiple linear regressions showed that 21.9% and 29.9% of the variance in rotifer density was explained by physicochemical factors and crustaceans, respectively. Larger rotifer density was possible in shallower lakes with higher concentration of inorganic nitrogen and less herbivorous crustaceans such as Sinocalanus dorrii and Daphnia. Redundancy analysis showed that the variances of rotifer species distribution explained by crustaceans and physicochemical factors were 26.9% and 31.0%, respectively. Further analysis demonstrated that the variances explained by pure crustaceans and pure physicochemical factors were 12.5% and 16.6%, respectively. However, these two percentages were not statistically different. Rotifer species distribution was strongly associated with Chl a and Moina micrura. Their coexistence with crustaceans seemed to be determined by their defense against potential predators and competitors.
Co-reporter:Dawen Zhang, Ping Xie, Jun Chen, Ming Dai, Tong Qiu, Yaqin Liu, Gaodao Liang
Chemosphere (August 2009) Volume 76(Issue 7) pp:974-981
Publication Date(Web):1 August 2009
DOI:10.1016/j.chemosphere.2009.04.034
This paper describes seasonal changes of microcystin-LR (MC-LR) and its glutathione (MC-LR-GSH) and cysteine conjugates (MC-LR-Cys) in three aquatic animals – snail (Bellamya aeruginosa), shrimp (Macrobrachium nipponensis) and silver carp (Hypophthalmichthys molitrix) collected from Lake Taihu, China. MC-LR, MC-LR-GSH, and MC-LR-Cys were determined by liquid chromatography electrospray ionization mass spectrum (LC–ESI-MS). The mean MC-LR concentrations in the hepatopancreas of snail and shrimp and liver of silver carp were 6.61, 0.24, and 0.027 μg g−1 dry weight (DW), respectively; while the average MC-LR-Cys concentrations were 0.50, 0.97, and 5.72 μg g−1 DW, respectively. MC-LR-GSH was usually not detectable in these samples. The above results suggest that: (1) in aquatic animals, especially fish, the main excretion form of MC-LR could be MC-LR-Cys, but not MC-LR-GSH, whereas MC-LR-Cys might play an important role in detoxication of MC-LR and (2) that efficiency of MC-LR-Cys formation differs among species. The main detoxication pathway of MC-LR in aquatic animals is suggested as follows: when MC-LR enters into liver/hepatopancreas, it firstly conjugates with polypeptide or protein (including GSH, PP-1 and 2A) containing Cys residues, perhaps also some free cysteine; subsequently, MC-LR-Cys is degraded from these polypeptide or protein; and finally is excreted from animals by the compound of MC-LR-Cys.
Co-reporter:Huihui Fan, Yan Cai, Ping Xie, Wuhan Xiao, Jun Chen, Wei Ji, Sujuan Zhao
Toxicology (7 May 2014) Volume 319() pp:69-74
Publication Date(Web):7 May 2014
DOI:10.1016/j.tox.2014.02.015
•MC-LR stabilizes c-myc protein, which is mainly by the PP2A/serine 62 pathway.•The TATA box for P1 is involved in the MC-LR-induced up-regulation of c-myc mRNA.•MC-LR has triple effects on c-myc protein.•C-myc response to MC-LR toxicity is mainly by the PP2A/serine 62 pathway.Microcystin-LR is the most toxic and the most frequently encountered toxin produced by the cyanobacteria in the contaminated aquatic environment. Previous studies have demonstrated that Microcystin-LR is a potential carcinogen for animals and humans, and the International Agency for Research on Cancer has classified Microcystin-LR as a possible human carcinogen. However, the precise molecular mechanisms of Microcystin-LR-induced carcinogenesis remain a mystery. C-myc is a proto-oncogene, abnormal expression of which contributes to the tumor development. Although several studies have demonstrated that Microcystin-LR could induce c-myc expression at the transcriptional level, the exact connection between Microcystin-LR toxicity and c-myc response remains unclear. In this study, we showed that the c-myc protein increased in HEK293 cells after exposure to Microcystin-LR. Coexpression of protein phosphatase 2A and two stable c-myc protein point mutants (either c-mycT58A or c-mycS62A) showed that Microcystin-LR increased c-myc protein level mainly through inhibiting protein phosphatase 2A activity which altered the phosphorylation status of serine 62 on c-myc. In addition, we also showed that Microcystin-LR could increase c-myc promoter activity as revealed by luciferase reporter assay. And the TATA box for P1 promoter of c-myc might be involved. Our results suggested that Microcystin-LR can stimulate c-myc transcription and stabilize c-myc protein, which might contribute to hepatic tumorigenesis in animals and humans.
Co-reporter:Tong Qiu, Ping Xie, Ying Liu, Guangyu Li, Qian Xiong, Le Hao, Huiying Li
Toxicology (4 March 2009) Volume 257(Issues 1–2) pp:86-94
Publication Date(Web):4 March 2009
DOI:10.1016/j.tox.2008.12.012
Deaths from microcystin toxication have widely been attributed to hypovolemic shock due to hepatic interstitial hemorrhage, while some recent studies suggest that cardiogenic complication is also involved. So far, information on cardiotoxic effects of MC has been rare and the underlying mechanism is still puzzling. The present study examined toxic effects of microcystins on heart muscle of rats intravenously injected with extracted MC at two doses, 0.16LD50 (14 μg MC-LReq kg−1 body weight) and 1LD50 (87 μg MC-LReq kg−1 body weight). In the dead rats, both TTC staining and maximum elevations of troponin I levels confirmed myocardial infarction after MC exposure, besides a serious interstitial hemorrhage in liver. In the 1LD50 dose group, the coincident falls in heart rate and blood pressure were related to mitochondria dysfunction in heart, while increases in creatine kinase and troponin I levels indicated cardiac cell injury. The corresponding pathological alterations were mainly characterized as loss of adherence between cardiac myocytes and swollen or ruptured mitochondria at the ultrastructural level. MC administration at a dose of 1LD50 not only enhanced activities and up-regulated mRNA transcription levels of antioxidant enzymes, but also increased GSH content. At both doses, level of lipid peroxides increased obviously, suggesting serious oxidative stress in mitochondria. Simultaneously, complex I and III were significantly inhibited, indicating blocks in electron flow along the mitochondrial respiratory chain in heart. In conclusion, the findings of this study implicate a role for MC-induced cardiotoxicity as a potential factor that should be considered when evaluating the mechanisms of death associated with microcystin intoxication in Brazil.
Co-reporter:Xiao -Ying Tan, Ping Xie, Zhi Luo, Hei-Zhao Lin, Yan-Hong Zhao, Wen-Qiu Xi
Aquaculture (25 January 2012) Volumes 326–329() pp:68-73
Publication Date(Web):25 January 2012
DOI:10.1016/j.aquaculture.2011.11.013
Co-reporter:Xiao-Ying Tan, Zhi Luo, Ping Xie, Xiao-Dong Li, Xiang-Jiang Liu, Wen-Qiu Xi
Aquaculture (22 December 2010) Volume 310(Issues 1–2) pp:186-191
Publication Date(Web):22 December 2010
DOI:10.1016/j.aquaculture.2010.10.011
Co-reporter:Le Hao, Ping Xie, Juan Fu, Guangyu Li, Qian Xiong, Huiying Li
Aquatic Toxicology (20 October 2008) Volume 90(Issue 1) pp:1-7
Publication Date(Web):20 October 2008
DOI:10.1016/j.aquatox.2008.07.006
Co-reporter:Yan Jiang, Ping Xie, Gaodao Liang
Aquaculture (2 March 2009) Volume 288(Issues 1–2) pp:1-6
Publication Date(Web):2 March 2009
DOI:10.1016/j.aquaculture.2008.10.025
Co-reporter:Guangyu Li, Ping Xie, Juan Fu, Le Hao, Qian Xiong, Huiying Li
Aquatic Toxicology (2 June 2008) Volume 88(Issue 1) pp:75-80
Publication Date(Web):2 June 2008
DOI:10.1016/j.aquatox.2008.03.007
Co-reporter:Le Hao, Ping Xie, Juan Fu, Guangyu Li, Qian Xiong, Huiying Li
Aquatic Toxicology (18 January 2009) Volume 91(Issue 1) pp:99
Publication Date(Web):18 January 2009
DOI:10.1016/j.aquatox.2008.11.011
Co-reporter:Songbo Wang, Ping Xie, Shikai Wu, Aiping Wu
Limnologica - Ecology and Management of Inland Waters (17 September 2007) Volume 37(Issue 3) pp:242-249
Publication Date(Web):17 September 2007
DOI:10.1016/j.limno.2007.02.002
A comparative limnological study was carried out to present a snapshot of crustacean zooplankton communities and their relations to environmental factors to test whether there is a consistent relationship between crustacean biomass and trophic indicators among lake groups with similar trophic conditions. The study lakes showed a wide range of trophic status, with total phosphorus (TP) ranging from 0.008 to 1.448 mg L−1, and chlorophyll a from 0.7 to 146.1 μg L−1, respectively. About 38 species of Crustacea were found, of which Cladocera were represented by 25 taxa (20 genera), and Copepoda by 13 taxa (11 genera). The most common and dominant species were Bosmina coregoni, Moina micrura, Diaphanosoma brachyurum, Cyclops vicinus, Thermocyclops taihokuensis, Mesocyclops notius and Sinocalanus dorrii. Daphnia was rare in abundance. Canonical correspondence analysis showed that except for four species (D. hyalina, S. dorrii, C. vicinus and M. micrura), almost all the dominant species had the same preference for environmental factors. Temperature, predatory cyclopoids and planktivorous fishes seem to be the key factors determining species distribution. TP was a relatively better trophic indicator than chlorophyll a to predict crustacean biomass. Within the three groups of lakes, however, there was no consistent relationship between crustacean biomass and trophic indicators. The possible reason might be that top-down and bottom-up control on crustaceans vary with lake trophic state. The lack of significant negative correlation between crustacean biomass and chlorophyll a suggests that there was little control of phytoplankton biomass by macrozooplankton in these shallow subtropical lakes.
Co-reporter:Juan Lin, Jun Chen, Jun He, Jing Chen, Qingyun Yan, Jizhong Zhou, Ping Xie
Toxicon (15 March 2015) Volume 96() pp:50-56
Publication Date(Web):15 March 2015
DOI:10.1016/j.toxicon.2015.01.011
•We firstly studied the shift of microbial functional genes in rat gut induced by MC-LR.•The enriched genes involved in metabolisms of chitin, starch, limonene and aromatics.•The enriched genes were mainly derived from bacterial and fungal pathogens.The short-term exposure to microcystin-LR (MC-LR, one of the most common and toxic variants generated by toxigenic cyanobacteria) induced gut dysfunction such as generation of reactive oxygen species, cell erosion and deficient intestinal absorption of nutrients. However, till now, little is known about its impact on gut microbial community, which has been considered as necessary metabolic assistant and stresses resistant entities for the host. This study was designed to reveal the shift of microbial functional genes in the gut of rat orally gavaged with MC-LR. GeoChip detected a high diversity of bacterial and fungal genes involved in basic metabolic processes and stress resistance. The results showed that the composition of functional genes was significantly changed in rat gut after one week of exposure to MC-LR, and we found some relatively enriched genes that are involved in carbon degradation including chitin, starch and limonene metabolism, and these genes were mainly derived from fungal and bacterial pathogens. In addition, we found large amounts of significantly enriched genes relevant to degradation of the specific carbon compounds, aromatics. The dysbiosis of bacterial and fungal flora gave an implication of pathogens invasion. The enriched gene functions could be linked to acute gastroenteritis induced by MC-LR.
Co-reporter:Le Hao, Ping Xie, Huiying Li, Guangyu Li, Qian Xiong, Qing Wang, Tong Qiu, Ying Liu
Toxicon (15 June 2010) Volume 55(Issue 7) pp:1378-1386
Publication Date(Web):15 June 2010
DOI:10.1016/j.toxicon.2010.02.015
This study explored the mechanisms of toxicity of microcystins by measuring the transcription levels of nine cytoskeletal genes (actin, tubulin, vimentin, ezrin, radixin, moesin, MAP1b, tau, stathmin) in the liver, kidney and spleen of male Wistar rats treated with microcystins at a dose of 80 μg MC-LReq kg−1 bw. Microcystins disrupted the transcriptional homeostasis of cytoskeletal genes in these organs. Changes in the transcription of four genes (β-actin, ezrin, radixin and tau) in liver, one gene (stathmin) in kidney, and one gene (radixin) in spleen were significantly correlated with the tissue concentration of microcystins. However, the influences on the transcription of most genes we studied were greater in the liver than in the kidney or spleen. The effects of microcystins on the transcription of cytoskeletal genes may explain some of the morphological and pathological changes observed in these organs and provide new information on the hepatotoxicity of these compounds. Additionally, transcriptional changes in tumor-associated cytoskeletal genes (ezrin, moesin and stathmin) that were observed in the present study provide a possible clue to the tumor-promoting potential of microcystins and their influences on the transcription of MAP1b and tau imply possible neurological toxicity of microcystins in vertebrates.
Co-reporter:Xuezhen Zhang, Ping Xie, Dapeng Li, Zechao Shi
Toxicon (15 June 2007) Volume 49(Issue 8) pp:1150-1157
Publication Date(Web):15 June 2007
DOI:10.1016/j.toxicon.2007.02.009
Alterations in hematological indices such as decreases in blood cell counts (RBC), hematocrit (Ht) and hemoglobin (Hb) concentrations are key symptoms of anemia. However, few experiments were conducted to examine changes in hematological indices of fish exposed to microcystins that are believed to be fatal to circulatory systems of vertebrates. An acute toxicological experiment was designed to study hematological changes of crucian carp injected intraperitoneally (i.p.) with extracted microcystins at two doses, 50 and 200 μg MC-LReq kg−1 body weight. After being i.p. injected with microcystins, the fish exhibited behavioral abnormity. There were significant decreases in RBC in the high-dose group, and in Ht and Hb concentrations in both dose groups, while erythrocyte sedimentation rate (ESR) significantly increased, indicating the appearance of normocytic anemia. There were no prominent changes in the three red cell indices, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). Increases in blood urea nitrogen (BUN) and creatinine (CR) in both dose groups suggest the occurrence of kidney impairment. Alteration in blood indices was reversible at the low dose group. Conclusively, anemia induced by kidney impairment was a key factor to cause abnormity of swimming behaviors and high mortality of crucian carp.
Co-reporter:Tong Qiu, Ping Xie, Zhixin Ke, Li Li, Longgen Guo
Toxicon (1 September 2007) Volume 50(Issue 3) pp:365-376
Publication Date(Web):1 September 2007
DOI:10.1016/j.toxicon.2007.04.006
Physiological and biochemical responses of four fishes with different trophic levels to toxic cyanobacterial blooms were studied in a large net cage in Meiliang Bay, a hypereutrophic region of Lake Taihu. We sampled four fishes: the phytoplanktivorous Hypophthalmichthys molitrix and Aristichthys nobilis, the omnivorous Carassius auratus, and the carnivorous Culter ilishaeformis. Alterations of the antioxidant (GSH) and the major antioxidant enzymes (CAT, SOD, GPx, GST) in livers were monitored monthly, and the ultrastructures of livers were compared between the bloom and post-bloom periods. During the cyanobacterial blooms, the phytoplanktivorous fishes displayed only slight ultrastructural changes in liver, while the carnivorous fish presented the most serious injury as swollen endomembrane system and morphologically altered nuclei in hepatocytes. Biochemically, the phytoplanktivorous fishes possessed higher basal GSH concentrations and better correlations between the major antioxidant enzymes in liver, which might be responsible for their powerful resistance to MCs. This article provided physiological and toxicological evidences for the possible succession of fish communities following occurrence of toxic cyanobacterial blooms and also for the applicability of using phytoplanktivorous fish to counteract toxic cyanobacterial blooms in natural waters.
Co-reporter:Xi Yang, Ping Xie, Yunzhen Yu, Hong Shen, ... Yuan Niu
Journal of Environmental Sciences (1 May 2015) Volume 31() pp:38-43
Publication Date(Web):1 May 2015
DOI:10.1016/j.jes.2014.07.034
We conducted an experiment to study the interaction effects of Microcystis aeruginosa and Pseudomonas pseudoalcaligenes on off-flavors in an algae/bacteria co-culture system at three temperatures (24, 28 and 32°C). Gas chromatography–mass spectrometry was applied to measure off-flavor compounds dimethyl sulfide (DMS), dimethyl trisulfide (DMTS), 2-methylisoborneol, geosmin (GEO) and β-cyclocitral. During the lag phase of co-cultured M. aeruginosa (first 15 days), P. pseudoalcaligenes significantly increased the production of DMS, DMTS and β-cyclocitral at all three temperatures. In the exponential phase of co-cultured M. aeruginosa (after 15 days), M. aeruginosa became the main factor on off-flavors in the co-culture system, and β-cyclocitral turned to the highest off-flavor compound. These results also indicated that DMS, DMTS and β-cyclocitral were the main off-flavor compounds in our M. aeruginosa/P. pseudoalcaligenes co-culture system. Univariate analysis was applied to investigate the effects of M. aeruginosa and P. pseudoalcaligenes on the production of off-flavors. The results demonstrated that both M. aeruginosa and P. pseudoalcaligenes could increase the production of DMS and DMTS, while β-cyclocitral was mainly determined by M. aeruginosa. Our results also provide some insights into understanding the relationship between cyanobacteria and heterotrophic bacteria.Download full-size image
Co-reporter:Xuezhen Zhang, Ping Xie, Weimin Wang, Dapeng Li, Li Li, Rong Tang, Hehua Lei, Zechao Shi
Toxicon (1 March 2008) Volume 51(Issue 3) pp:449-456
Publication Date(Web):1 March 2008
DOI:10.1016/j.toxicon.2007.11.005
A laboratory toxic experiment was conducted to examine dose-dependent effects of extracted microcystins (MCs) on embryonic development, larval growth and histopathological changes of southern catfish (Silurus meridionalis). Fertilized eggs were incubated in solutions with four concentrations of MCs (0, 1, 10, 100 μg MC-LReq l−1). Higher MCs retarded egg development (2–10 h delays) and larval growth, reduced hatching rate (up to 45%), and caused high malformation rate (up to 15%) and hepatocytes damage (characterized by disorganization of cell structure and a loss of adherence between hepatocytes, cellular degeneration with vacuolar hepatocytes and marginal nuclei, even hepatocellular necrosis). A 10 μg MC-LReq l−1 is close to a high concentration in natural cyanobacterial blooms, suggesting a possible existence of such toxic effects in eutrophic waters.
Co-reporter:Pengling Shi, Hong Shen, Wenjing Wang, Wenjie Chen, Ping Xie
Journal of Environmental Sciences (1 August 2015) Volume 34() pp:28-36
Publication Date(Web):1 August 2015
DOI:10.1016/j.jes.2015.03.003
In order to find effective measures to control diatom blooms, a better understanding of the physiological characteristics of nutrient uptake in diatoms is needed. A study of P and Si-uptake kinetics for diatom species from two light regimes was conducted at low (LL), moderate (ML) and high light intensities (HL) (2, 25 and 80 μmol photons/(m2·sec)), respectively. The results showed that P uptake of diatoms was heavily influenced by historic light regimes. P affinity changed with growth and photosynthetic activity. The lowest half saturation constant for P uptake (Km(P)) was under HL for high-light adapted diatoms while the lowest half-saturation constant for low-light adapted diatoms was observed under LL. The Si half-saturation constant (Km(Si)) increased with increasing light intensities for pennate diatoms but decreased for centric diatoms. Diatom volumes were correlated with the maximum Si uptake rates (Vm(Si)) at HL and Km(Si) at ML and HL for six diatom species. Our results imply that when we assess the development of diatom blooms we should consider light intensity and cell volume in addition to ambient Si or P concentration. The relationship between light intensity and P-uptake suggests that we can find suitable methods to control diatom blooms on the basis of reducing phytoplankton activity of P-uptake and photosynthesis simultaneously.Download full-size image
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