Investigating factors affecting growth and cellular mcyB transcripts of Microcystis aeruginosa PCC 7806 using real-time PCR

Semary, Nermin Adel El

doi:10.1007/s13213-010-0024-5

Cited by 15 publications

(10 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Several studies supported the relationship between the algal growth rate and the toxin content. 16,22 On the basis of the potency estimation and the ROS inhibition assay, our study speculated that the production of intra-microcystin in M. aeruginosa induced by metalaxyl primary originated from ROS and genetic transcription. A previous study indicated that mcy gene knockout algae were more vulnerable to H 2 O 2 than the normal toxic strain, which indicated a potential relationship between ROS and mcy genes.…”

Section: Resultsmentioning

confidence: 93%

Potential Risk and Mechanism of Microcystin Induction by Chiral Metalaxyl

Wang

Yang

Tang

et al. 2018

Environ. Sci. Technol. Lett.

View full text Add to dashboard Cite

Pesticide-induced oxidative stress has been widely observed in aquatic algae. The production of microcystin caused by Microcystis aeruginosa intensified under the oxidative stress induced by solar radiation during an algal bloom. However, whether oxidative stress caused by the pollutants also contributed to toxic microcystin generation and the potential mechanism remain unknown, especially for chiral environmental contaminants. Metalaxyl, a high-volume chiral fungicide, was selected as the model to compare the risks to M. aeruginosa. Our results revealed a significant induction of algal growth or photosynthetic pigments at 30−50 mg/L R-metalaxyl (fungicidally active enantiomer) compared with 300−400 mg/L racmetalaxyl at 48 h. At the nontoxic time point, the lowest observed effect concentration (LOEC) of reactive oxygen species (ROS) induction was 10 mg/L in R-metalaxyl, which was 30 times lower than the corresponding value for the rac form. The LOECs of extra-and intra-microcystin induction of R-metalaxyl were 3.3 and 30.0 times higher than that of rac-metalaxyl, respectively. R-Metalaxyl enantioselectively induced M. aeruginosa genes encoding components of microcystin synthesis and secretion. The potency estimation revealed that only the level of ROS and genes encoding microcystin synthesis were positively correlated with the upregulation of intra-microcystin. Furthermore, we confirmed that attenuation of ROS by N-acetylcysteine mostly alleviated intra-microcystin induction. This demonstrates that the enantiomer that can cause oxidative stress may pose risks to the aquatic system, especially during an algal bloom.

show abstract

Section: Resultsmentioning

confidence: 93%

Potential Risk and Mechanism of Microcystin Induction by Chiral Metalaxyl

Wang

Yang

Tang

et al. 2018

Environ. Sci. Technol. Lett.

View full text Add to dashboard Cite

show abstract

“…17 Levels of microcystin expression are highly variable according to environmental conditions and individual genotype, and therefore it is possible for a site to have a relatively low concentration of Microcystis yet produce significant amounts of microcystins, or have a high concentration of Microcystis but be nontoxic. 38,39 Microcystis Distribution Patterns. Figure 1 displays the relative proportions of Microcystis abundances across the lake based on qPCR derived total and toxigenic Microcystis cell equivalents from all sampling sites and sampling transects.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Spatiotemporal Patterns and Ecophysiology of Toxigenic Microcystis Blooms in Lake Taihu, China: Implications for Water Quality Management

Otten

Qin

et al. 2012

Environ. Sci. Technol.

205

105

View full text Add to dashboard Cite

Whole lake monitoring of hypertrophic Lake Taihu, China, was conducted during the summers of 2009-2010, with the intent of identifying environmental factors influencing Microcystis bloom formation and promoting the growth of toxigenic strains (mcyE possessing). Low N:P ratios (replete N & P)appeared to select for toxigenic populations of Microcystis spp., whereas nontoxic Microcystis spp. strains were dominant in more nutrient limited regions of the lake. Chlorophyll a (Adj. R(2) = 0.83, p < 0.0001) was equally predicative of microcystin variance across the lake as fluorescence based real-time quantitative PCR (qPCR) measurements of microcystin synthetase E (mcyE) gene equivalents (Adj. R(2) = 0.85, p < 0.0001). Interestingly, chlorophyll a was identified as a more robust and useful metric for predicting microcystin concentrations than qPCR measurements enumerating the total Microcystis population based on c-phycocyanin (α subunit; cpcA) gene equivalents (Adj. R(2) = 0.61, p < 0.0001). Overall, the lakewide composition of Microcystis spp. was highly variable over time and space, and on average the population consisted of 36 ± 12% potentially toxic cells. On the basis of this study's findings, a framework for the design and implementation of a water safety plan for Taihu water quality managers and public health officials is proposed.

show abstract

“…Some environmental factors are also known to regulate mcyB transcription. The main one is the light, both its intensity, and its quality (Kaebernick et al, 2000;El Semary, 2010). However, the cyanobacteria we sampled had been buried in the sediments for a long period of time and so in total darkness, and our sampling strategy meant that they were not exposed to light.…”

Section: Discussionmentioning

confidence: 99%