Cylindrospermopsis raciborskii and its highly similar relatives Raphidiopsis species have been recognized as globally invasive and expansive filamentous cyanobacteria causing water blooms.Reports on C.raciborsMi/Raphi...Cylindrospermopsis raciborskii and its highly similar relatives Raphidiopsis species have been recognized as globally invasive and expansive filamentous cyanobacteria causing water blooms.Reports on C.raciborsMi/Raphidiopsis species and their harmful metabolites such as hepatotoxic cylindrospermopsins(CYNs)in Chinese waters have been increasing,but mostly restricted to the southern regions of China.To further explore the existence and distribution of C.raciborskii in China,six water samples from Beijing city were morphologically and molecularly examined.Five samples of the six were shown to have Cylindrospermopsis filaments with straight and spiral morphotypes.PCR detection targeting on Cylindrospermopsis/Raphidiopsis specific 16S rRNA gene region also showed the positive amplification,and such amplifications were confirmed by sequencing and phylogenetic analysis.As well,three of the five Cylindrospermopsis containing samples were shown to have cyrJ--a gene of CYN synthesis gene duster.The results represented the presence of toxic Cylindrospermopsis at the most northern line in China so far,indicating rapid expansion of this harmful invasive cyanobacterium.It is strongly suggested that the monitoring on C.raciborskii/Raphidiopsis species and their production of cylindrospermopsin should be emphasized in Beijing and even more northem parts of China.展开更多
In recent years,Cylindrospermopsis raciborskii blooms have been widely found worldwide.Topics dealing with the mitigation of C.raciborskii bloom is of great importance for toxins produced could threaten public health....In recent years,Cylindrospermopsis raciborskii blooms have been widely found worldwide.Topics dealing with the mitigation of C.raciborskii bloom is of great importance for toxins produced could threaten public health.The paper first investigated C.raciborskii dynamics over three years following sediment dredging in a shallow eutrophic Lake Dongqian(China).Based on rpoC1 gene copies,C.raciborskii bloom formed with average density of 1.30×10^(6) cells/L on July 2009.One year later after sediment dredging,C.raciborskii cell density decreased below 1.17×10^(5) cells/L or under detected limits during summer days on 2010.While two years later,the C.raciborskii bloom period was returned with markedly increased cell density reaching up to 4.15×10^(7) cells/L on October 2011,and the maximum peak density was shown at 20.3C that was much lower than reported optimal growth temperature.Inferred from Spearman correlation analysis,linear regression showed C.raciborskii density was significant and positive with pH and SD,whereas they were significant and negative with TP and DO.Multiple regression analysis further demonstrated that TN,TP,SRP,pH and DO provided the best model and explained 53.1% of the variance in C.raciborskii dynamics.The approaches managing nutrients reduction might not control C.raciborskii bloom as extremely low TN(avg.0.18 mg/L)and TP concentrations(avg.0.05 mg/L)resulted in the highest C.raciborskii cell density after sediment dredging.展开更多
Freshwater lakes globally are witnessing an escalation in the frequency and intensity of cyanobacterial harmful blooms.However,underlying factors influencing the succession or coexistence of cyanobacteria,especially f...Freshwater lakes globally are witnessing an escalation in the frequency and intensity of cyanobacterial harmful blooms.However,underlying factors influencing the succession or coexistence of cyanobacteria,especially filamentous ones,remain poorly understood.Lake Honghu,a Ramsar Wetland of International Importance with degrading aquatic ecological quality,served as a case study to elucidate the intricate relationship between environmental changes and cyanobacterial dynamics.Our analysis revealed a significant increase in the dominance of filamentous cyanobacteria,marked by high spatiotemporal variability in community structure.This dominance of filamentous diazotrophic cyanobacteria is attributed to a decrease in the ratio of dissolved inorganic nitrogen to total phosphorus and their capacity to utilize organic phosphorus in phosphorus-deficient conditions.Species-specific density variations were linked to diverse environmental factors,with total nitrogen or total phosphorus concentration remaining as a crucial factor influencing dominant cyanobacterial density fluctuations.The dominance of low-temperature-tolerant Aphanizomenon and Pseudanabaena was evident in spring and winter,whereas Dolichospermum and Cylindrospermopsis,which prefer higher temperatures,thrived in summer and autumn.Additionally,non-algal turbidity and heterogeneity can potentially alter the competitive outcome among filamentous cyanobacteria or foster coexistence under conditions of elevated temperatures and nutrient limitation.This study predicts that filamentous cyanobacteria may spread and persist in lakes spanning a wide trophic range.Current findings enhance our comprehen-sion of the dynamic responses exhibited by filamentous bloom-forming cyanobacteria in the face of environmental changes within shallow eutrophic lakes and provide valuable insights for lake managers involved in the remediation of degraded shallow lakes.展开更多
It is reported for the first time in Brazil and South America the presence of cylindrospermopsin (CYN) in water supply reservoirs. CYN is a powerful hepatotoxic alkaloid implicated in outbreaks of human sicknesses. We...It is reported for the first time in Brazil and South America the presence of cylindrospermopsin (CYN) in water supply reservoirs. CYN is a powerful hepatotoxic alkaloid implicated in outbreaks of human sicknesses. We detected CYN in different sources of water in Northeastern Brazil using molecular and immunological techniques. The highest concentrations of toxin occurred in the Jucazinho reservoir with the phytoplankton containing the potentially CYN-producing C. raciborskii and Sphaerospermopsis aphanizomenoides (previously known as Aphanizomenon aphanizomenoides). The polyketide synthase (PKS) and peptide synthetase (PS), which are directly related to the ability to produce CYN, were found in all the analyzed samples. The result of the present study emphasizes the need to improve monitoring of CYN in water bodies used for drinking and recreation, in order to avoid exposure of human populations to this toxin.展开更多
Cyanobacterial blooms have become a worldwide concern due to the production of toxins harmful to humans and animals. In Brazil and worldwide, microcystins are the most frequently found cyanotoxin in water bodies. Four...Cyanobacterial blooms have become a worldwide concern due to the production of toxins harmful to humans and animals. In Brazil and worldwide, microcystins are the most frequently found cyanotoxin in water bodies. Four important reservoirs in Brazil’s Southeast and Northeast regions were sampled to identify the cyanobacteria community and the occurrence of potential toxin-producing species in the country’s public supply reservoirs. A total of 14 taxa were identi-fied, 11 of which are known as potential toxin producers. Potentially toxic cyanobacteria were recorded at concentra-tions above 20,000 cells.ml-1 in all samples from all four reservoirs, thus requiring microcystin monitoring in drinking water according to Brazilian legislation. Although the sample from Mundaú reservoir showed the highest concentration of microcystins in water, it had one of the lowest values of cells.ml-1, which demonstrates the non-correspondence between these two parameters. This calls into question the existence of a minimum level of potentially toxic cyanobacteria cells to merit the monitoring of microcystins in the treated water from these sources.展开更多
基金Supported by the National Natural Science Foundation of China(No.41561005)
文摘Cylindrospermopsis raciborskii and its highly similar relatives Raphidiopsis species have been recognized as globally invasive and expansive filamentous cyanobacteria causing water blooms.Reports on C.raciborsMi/Raphidiopsis species and their harmful metabolites such as hepatotoxic cylindrospermopsins(CYNs)in Chinese waters have been increasing,but mostly restricted to the southern regions of China.To further explore the existence and distribution of C.raciborskii in China,six water samples from Beijing city were morphologically and molecularly examined.Five samples of the six were shown to have Cylindrospermopsis filaments with straight and spiral morphotypes.PCR detection targeting on Cylindrospermopsis/Raphidiopsis specific 16S rRNA gene region also showed the positive amplification,and such amplifications were confirmed by sequencing and phylogenetic analysis.As well,three of the five Cylindrospermopsis containing samples were shown to have cyrJ--a gene of CYN synthesis gene duster.The results represented the presence of toxic Cylindrospermopsis at the most northern line in China so far,indicating rapid expansion of this harmful invasive cyanobacterium.It is strongly suggested that the monitoring on C.raciborskii/Raphidiopsis species and their production of cylindrospermopsin should be emphasized in Beijing and even more northem parts of China.
基金The National Key Research and Development Program of China(2017YFA0605003)the National Natural Science Foundation of China(51922010,91751114,41521003,31700404),supported this study.
文摘In recent years,Cylindrospermopsis raciborskii blooms have been widely found worldwide.Topics dealing with the mitigation of C.raciborskii bloom is of great importance for toxins produced could threaten public health.The paper first investigated C.raciborskii dynamics over three years following sediment dredging in a shallow eutrophic Lake Dongqian(China).Based on rpoC1 gene copies,C.raciborskii bloom formed with average density of 1.30×10^(6) cells/L on July 2009.One year later after sediment dredging,C.raciborskii cell density decreased below 1.17×10^(5) cells/L or under detected limits during summer days on 2010.While two years later,the C.raciborskii bloom period was returned with markedly increased cell density reaching up to 4.15×10^(7) cells/L on October 2011,and the maximum peak density was shown at 20.3C that was much lower than reported optimal growth temperature.Inferred from Spearman correlation analysis,linear regression showed C.raciborskii density was significant and positive with pH and SD,whereas they were significant and negative with TP and DO.Multiple regression analysis further demonstrated that TN,TP,SRP,pH and DO provided the best model and explained 53.1% of the variance in C.raciborskii dynamics.The approaches managing nutrients reduction might not control C.raciborskii bloom as extremely low TN(avg.0.18 mg/L)and TP concentrations(avg.0.05 mg/L)resulted in the highest C.raciborskii cell density after sediment dredging.
基金supported by the National Key Research and Development Program of China(No.2018YFD0900701)the National Natural Science Foundation of China(No.42177246)+2 种基金Additional support was provided by Yunnan Province-Kunming City Major Science and Technology Project(No.202202AH210006)the convenience provided by workstation of academician Liu Yongding in Kunming(No.YSZJGZZ-2020018)The Natural Science Foundation of Hunan Province(No.2022JJ30691)also supported this research.
文摘Freshwater lakes globally are witnessing an escalation in the frequency and intensity of cyanobacterial harmful blooms.However,underlying factors influencing the succession or coexistence of cyanobacteria,especially filamentous ones,remain poorly understood.Lake Honghu,a Ramsar Wetland of International Importance with degrading aquatic ecological quality,served as a case study to elucidate the intricate relationship between environmental changes and cyanobacterial dynamics.Our analysis revealed a significant increase in the dominance of filamentous cyanobacteria,marked by high spatiotemporal variability in community structure.This dominance of filamentous diazotrophic cyanobacteria is attributed to a decrease in the ratio of dissolved inorganic nitrogen to total phosphorus and their capacity to utilize organic phosphorus in phosphorus-deficient conditions.Species-specific density variations were linked to diverse environmental factors,with total nitrogen or total phosphorus concentration remaining as a crucial factor influencing dominant cyanobacterial density fluctuations.The dominance of low-temperature-tolerant Aphanizomenon and Pseudanabaena was evident in spring and winter,whereas Dolichospermum and Cylindrospermopsis,which prefer higher temperatures,thrived in summer and autumn.Additionally,non-algal turbidity and heterogeneity can potentially alter the competitive outcome among filamentous cyanobacteria or foster coexistence under conditions of elevated temperatures and nutrient limitation.This study predicts that filamentous cyanobacteria may spread and persist in lakes spanning a wide trophic range.Current findings enhance our comprehen-sion of the dynamic responses exhibited by filamentous bloom-forming cyanobacteria in the face of environmental changes within shallow eutrophic lakes and provide valuable insights for lake managers involved in the remediation of degraded shallow lakes.
文摘It is reported for the first time in Brazil and South America the presence of cylindrospermopsin (CYN) in water supply reservoirs. CYN is a powerful hepatotoxic alkaloid implicated in outbreaks of human sicknesses. We detected CYN in different sources of water in Northeastern Brazil using molecular and immunological techniques. The highest concentrations of toxin occurred in the Jucazinho reservoir with the phytoplankton containing the potentially CYN-producing C. raciborskii and Sphaerospermopsis aphanizomenoides (previously known as Aphanizomenon aphanizomenoides). The polyketide synthase (PKS) and peptide synthetase (PS), which are directly related to the ability to produce CYN, were found in all the analyzed samples. The result of the present study emphasizes the need to improve monitoring of CYN in water bodies used for drinking and recreation, in order to avoid exposure of human populations to this toxin.
文摘Cyanobacterial blooms have become a worldwide concern due to the production of toxins harmful to humans and animals. In Brazil and worldwide, microcystins are the most frequently found cyanotoxin in water bodies. Four important reservoirs in Brazil’s Southeast and Northeast regions were sampled to identify the cyanobacteria community and the occurrence of potential toxin-producing species in the country’s public supply reservoirs. A total of 14 taxa were identi-fied, 11 of which are known as potential toxin producers. Potentially toxic cyanobacteria were recorded at concentra-tions above 20,000 cells.ml-1 in all samples from all four reservoirs, thus requiring microcystin monitoring in drinking water according to Brazilian legislation. Although the sample from Mundaú reservoir showed the highest concentration of microcystins in water, it had one of the lowest values of cells.ml-1, which demonstrates the non-correspondence between these two parameters. This calls into question the existence of a minimum level of potentially toxic cyanobacteria cells to merit the monitoring of microcystins in the treated water from these sources.
