Three minor microcystins have been isolated from a Planktothrix rubescens strain.Their structures have been elucidated by one-and two-dimensional NMR spectroscopy and high-resolution tandem mass spectrometry as the co...Three minor microcystins have been isolated from a Planktothrix rubescens strain.Their structures have been elucidated by one-and two-dimensional NMR spectroscopy and high-resolution tandem mass spectrometry as the compounds[Asp^(3),(E)-Dhb^(7)]MC-LY(1),[Asp^(3),(E)-Dhb^(7)]MC-HtyW(2),and[Asp^(3),(E)-Dhb^(7)]MC-LW(3).The amino acids found at the variable positions 2 and 4 of the microcystin core structure are in accordance with the predicted amino acid substrate activation selectivities of the non-ribosomal peptide synthetases McyA and McyB described earlier for this strain.All structural microcystin variants produced by this strain were shown to inhibit protein phosphatase 1 in the nanomolar range.展开更多
Lake mixing influences aquatic chemical properties and microbial community composition,and thus,we hypothesized that it would alter microbial community assembly and interac-tion.To clarify this issue,we explored the c...Lake mixing influences aquatic chemical properties and microbial community composition,and thus,we hypothesized that it would alter microbial community assembly and interac-tion.To clarify this issue,we explored the community assembly processes and cooccurrence networks in four seasons at two depths(epilimnion and hypolimnion)in a mesotrophic and stratified lake(Chenghai Lake),which formed stratification in the summer and turnover in the winter.During the stratification period,the epilimnion and hypolimnion went through contrary assembly processes but converged to similar assembly patterns in the mixing pe-riod.In a highly homogeneous selection environment,species with low niche breadth were filtered,resulting in decreased species richness.Water mixing in the winter homogenized the environment,resulting in a simpler microbial cooccurrence network.Interestingly,we observed a high abundance of the cyanobacterial genus Planktothrix in the winter,proba-bly due to nutrient redistribution and Planktothrix adaptivity to the winter environment in which mixing played important roles.Our study provides deeper fundamental insights into how environmental factors influence microbial community structure through community assembly processes.展开更多
在近年来对水华蓝藻的调查中,确定了我国一水华蓝藻新记录属——拟浮丝藻属Planktothricoides(WoIoszyńska) Suda et Watanabe 2002。文中对该属及该属一个新记录种的主要形态学特征进行了描述,并对其相近属浮丝藻属Planktothrix进行...在近年来对水华蓝藻的调查中,确定了我国一水华蓝藻新记录属——拟浮丝藻属Planktothricoides(WoIoszyńska) Suda et Watanabe 2002。文中对该属及该属一个新记录种的主要形态学特征进行了描述,并对其相近属浮丝藻属Planktothrix进行了形态学比较研究。展开更多
在从武汉东湖水样中培养分离水华蓝藻噬藻体(Planktothrix agardhii Virus from Lake Donghu,PaV-LD)的基础上,对在不同条件培养的宿主蓝藻细胞中,PaV-LD增殖效率及裂解作用进行了测定分析。分别将PaV-LD接种到生长期、半连续培养更新...在从武汉东湖水样中培养分离水华蓝藻噬藻体(Planktothrix agardhii Virus from Lake Donghu,PaV-LD)的基础上,对在不同条件培养的宿主蓝藻细胞中,PaV-LD增殖效率及裂解作用进行了测定分析。分别将PaV-LD接种到生长期、半连续培养更新率或光照不同的宿主蓝藻液中,并采用稀释培养计数(Mostprobable number,MPN)方法与电镜观察,测定子代PaV-LD释放量及宿主细胞的裂解作用。结果显示:对数生长期宿主蓝藻单个细胞中子代PaV-LD的平均释放量为350感染单位(Infectious Units,IU/cell),显著高于稳定生长期的平均释放量110 IU/cell。在用新鲜培养基更新率为0%、35%、50%和65%的半连续培养宿主蓝藻中,接种PaV-LD 5d之后,噬藻体的释放量分别约为50 IU/cell、70 IU/cell、220 IU/cell或310 IU/cell,表明子代PaV-LD释放率随培养基更新率的增加而显著提高。在光照条件下感染3—4d后,宿主蓝藻细胞充分裂解,并释放大量子代PaV-LD,滴度可由初始7.00×103IU/mL快速增加到8.56×107IU/mL;但在遮光条件下,同样感染的蓝藻细胞未见裂解,也检测不到释放的子代噬藻体。电镜观察显示,在光照条件下感染的蓝藻细胞类囊体膜结构消失,而大量子代PaV-LD颗粒主要分布在原有类囊体的部位。显然,宿主蓝藻细胞的培养条件和状态可能对获得噬藻体纯培养有决定性影响。展开更多
为研究我国浮丝藻(Planktothrix Anagnostidis et Komárek)的毒素相关基因,选取分离自我国不同省份水体的13株阿氏浮丝藻,通过PCR检测其微囊藻毒素合成酶基因mcyA、mcyE及mcyT研究其毒素基因特性。PCR结果表明除mcyT之外其他引物...为研究我国浮丝藻(Planktothrix Anagnostidis et Komárek)的毒素相关基因,选取分离自我国不同省份水体的13株阿氏浮丝藻,通过PCR检测其微囊藻毒素合成酶基因mcyA、mcyE及mcyT研究其毒素基因特性。PCR结果表明除mcyT之外其他引物检测均无扩增产物,说明这13株浮丝藻不具备产微囊藻毒素的能力。通过克隆测序得到mcyT序列,并进行分子系统分析,构建了关于mcyT序列的Neighbor-Joining系统树,结果表明mcyT序列可以将产毒与不产毒浮丝藻分为两大独立的分支,两个分支之间的最低序列相似度分别为98.5%和99.1%。研究结果可为后续研究我国浮丝藻的微囊藻毒素合成相关基因的多样性以及分子监测提供参考。展开更多
In late May 2016, a cyanobacterial harmful algal bloom(cHAB) was detected in the Maumee River, the largest tributary to Lake Erie, the southernmost lake of the Laurentian Great Lakes system. Testing on 31 May identifi...In late May 2016, a cyanobacterial harmful algal bloom(cHAB) was detected in the Maumee River, the largest tributary to Lake Erie, the southernmost lake of the Laurentian Great Lakes system. Testing on 31 May identified Planktothrix agardhii as the dominant cyanobacterium with cell abundance exceeding 1.7×10~9 cells/L and total microcystins(MC) reaching 19 μg/L MC-LR equivalents, a level over 10-fold higher than the 2015 revised U.S. Environmental Protection Agency(EPA) national health advisory levels for drinking water exposure to adults. Low river discharge coincident with negligible precipitation through the latter half of May coincided with an 80% decline in river turbidity that likely favored bloom formation by a low-light adapted P. agardhii population. Also contributing to the c HAB were high initial nutrient loads and an increase of the river temperature from 13℃ to 26℃ over this same period. The bloom persisted through 5 June with microcystins exceeding 22 μg/L MC-LR equivalents at the bloom peak. By 6 June, the river had returned to its muddy character following a rain event and sampling on 7 June detected only low levels of toxin(<0.6 μg/L) at public water systems located near the bloom origin. The elevated toxin production associated with this early onset bloom was without precedent for the Maumee River and an unique attribute of the c HAB was the high proportion of potentially-toxic genotypes. Whereas Planktothrix spp. is common in lotic environments, and has been previously detected in the Maumee, blooms are not commonly reported. This early onset, microcystin-producing c HAB provided a rare opportunity to glean insights into environmental factors that promote bloom development and dominance by Planktothrix in lotic environments.展开更多
基金supported by the German Federal Ministry of Economics and Technology(KF2766301SB0)the Leibniz-Institut fur Molekulare Phamakologie(FMP),the Austrian Science Fund(P24070)the Austrian Climate Research Program(ACRP)project RADICAL(Risk Analysis of Direct and Indirect Climate effects on deep Austrian Lake Ecosystems).
文摘Three minor microcystins have been isolated from a Planktothrix rubescens strain.Their structures have been elucidated by one-and two-dimensional NMR spectroscopy and high-resolution tandem mass spectrometry as the compounds[Asp^(3),(E)-Dhb^(7)]MC-LY(1),[Asp^(3),(E)-Dhb^(7)]MC-HtyW(2),and[Asp^(3),(E)-Dhb^(7)]MC-LW(3).The amino acids found at the variable positions 2 and 4 of the microcystin core structure are in accordance with the predicted amino acid substrate activation selectivities of the non-ribosomal peptide synthetases McyA and McyB described earlier for this strain.All structural microcystin variants produced by this strain were shown to inhibit protein phosphatase 1 in the nanomolar range.
基金This work was supported by the National Natural Science Foundation of China(No.51578537)Chinese Academy of Sciences(No.QYZDY-SSW-DQC004)。
文摘Lake mixing influences aquatic chemical properties and microbial community composition,and thus,we hypothesized that it would alter microbial community assembly and interac-tion.To clarify this issue,we explored the community assembly processes and cooccurrence networks in four seasons at two depths(epilimnion and hypolimnion)in a mesotrophic and stratified lake(Chenghai Lake),which formed stratification in the summer and turnover in the winter.During the stratification period,the epilimnion and hypolimnion went through contrary assembly processes but converged to similar assembly patterns in the mixing pe-riod.In a highly homogeneous selection environment,species with low niche breadth were filtered,resulting in decreased species richness.Water mixing in the winter homogenized the environment,resulting in a simpler microbial cooccurrence network.Interestingly,we observed a high abundance of the cyanobacterial genus Planktothrix in the winter,proba-bly due to nutrient redistribution and Planktothrix adaptivity to the winter environment in which mixing played important roles.Our study provides deeper fundamental insights into how environmental factors influence microbial community structure through community assembly processes.
文摘在近年来对水华蓝藻的调查中,确定了我国一水华蓝藻新记录属——拟浮丝藻属Planktothricoides(WoIoszyńska) Suda et Watanabe 2002。文中对该属及该属一个新记录种的主要形态学特征进行了描述,并对其相近属浮丝藻属Planktothrix进行了形态学比较研究。
文摘为研究我国浮丝藻(Planktothrix Anagnostidis et Komárek)的毒素相关基因,选取分离自我国不同省份水体的13株阿氏浮丝藻,通过PCR检测其微囊藻毒素合成酶基因mcyA、mcyE及mcyT研究其毒素基因特性。PCR结果表明除mcyT之外其他引物检测均无扩增产物,说明这13株浮丝藻不具备产微囊藻毒素的能力。通过克隆测序得到mcyT序列,并进行分子系统分析,构建了关于mcyT序列的Neighbor-Joining系统树,结果表明mcyT序列可以将产毒与不产毒浮丝藻分为两大独立的分支,两个分支之间的最低序列相似度分别为98.5%和99.1%。研究结果可为后续研究我国浮丝藻的微囊藻毒素合成相关基因的多样性以及分子监测提供参考。
基金Supported by a Harmful Algal Bloom Research Initiative Grant(No.R/HAB-2-ODHE)from the Ohio Department of Higher Education(GSB,RMLM)Ohio Sea Grant College Program grant R/ER-114(GSB,RMLM)
文摘In late May 2016, a cyanobacterial harmful algal bloom(cHAB) was detected in the Maumee River, the largest tributary to Lake Erie, the southernmost lake of the Laurentian Great Lakes system. Testing on 31 May identified Planktothrix agardhii as the dominant cyanobacterium with cell abundance exceeding 1.7×10~9 cells/L and total microcystins(MC) reaching 19 μg/L MC-LR equivalents, a level over 10-fold higher than the 2015 revised U.S. Environmental Protection Agency(EPA) national health advisory levels for drinking water exposure to adults. Low river discharge coincident with negligible precipitation through the latter half of May coincided with an 80% decline in river turbidity that likely favored bloom formation by a low-light adapted P. agardhii population. Also contributing to the c HAB were high initial nutrient loads and an increase of the river temperature from 13℃ to 26℃ over this same period. The bloom persisted through 5 June with microcystins exceeding 22 μg/L MC-LR equivalents at the bloom peak. By 6 June, the river had returned to its muddy character following a rain event and sampling on 7 June detected only low levels of toxin(<0.6 μg/L) at public water systems located near the bloom origin. The elevated toxin production associated with this early onset bloom was without precedent for the Maumee River and an unique attribute of the c HAB was the high proportion of potentially-toxic genotypes. Whereas Planktothrix spp. is common in lotic environments, and has been previously detected in the Maumee, blooms are not commonly reported. This early onset, microcystin-producing c HAB provided a rare opportunity to glean insights into environmental factors that promote bloom development and dominance by Planktothrix in lotic environments.
