Effects of hydrogen peroxide on cyanobacteria and microcystins in irrigation water.

A new paper by Spoof et al. in Environmental Science and Pollution Research reports a series of experiments where lysis of cyanobacteria in abstracted lake water was induced by the use of hydrogen peroxide.

From the abstract:

This paper reports a series of experiments where lysis of cyanobacteria in abstracted lake water was induced by the use of hydrogen peroxide and the fate of released MCs was followed. The hydrogen peroxide–treated water was then used for spray irrigation of cultivated spinach and possible toxin accumulation in the plants was monitored. The water abstracted from Lake Köyliönjärvi, SW Finland, contained fairly low concentrations of intracellular MC prior to the hydrogen peroxide treatment (0.04 μgL −1 in July to 2.4 μgL −1 in September 2014). Hydrogen peroxide at sufficient doses was able to lyse cyanobacteria efficiently but released MCs were still present even after the application of the highest hydrogen peroxide dose of 20 mg L−1. No traces of MC were detected in the spinach leaves. The viability of moving phytoplankton and zooplankton was also monitored after the application of hydrogen peroxide. Hydrogen peroxide at 10 mg L−1 or higher had a detrimental effect on the moving phytoplankton and zooplankton.

The paper acknowledges CYANOCOST.

Reference:

Spoof, L., Jaakkola, S., Važić, T. Važić, T., Häggqvist, K., Kirkkala, T., Ventelä, A-M., Kirkkala, T., Svirčev, Z., Meriluoto, J. Elimination of cyanobacteria and microcystins in irrigation water—effects of hydrogen peroxide treatment. Environ Sci Pollut Res (2020). https://doi.org/10.1007/s11356-019-07476-x

New research sheds light on the underlying mechanisms of 2,4 DABA neurotoxic effects

A new paper by S. Spacic et al. in Aquatic Toxicology, presents important findings with regards to the mechanisms underlying 2,4-DABA neurotoxicity. From the abstract:

“Recent studies suggest that 2,4-DABA, a neurotoxic excitatory amino acid present in virtually all environments, but predominantly in aquatic ecosystems may be a risk factor for development of neurodegenerative diseases in animals and humans. Despite its neurotoxicity and potential environmental importance, mechanisms underlying the excitatory and putative excitotoxic action of 2,4-DABA in neurons are still unexplored. We previously reported on extensive two-stage membrane depolarization and functional disturbances in leech Retzius neurons induced by 2,4-DABA. Current study presents the first detailed look into the electrophysiological processes leading to this depolarization. Intracellular recordings were performed on Retzius neurons of the leech Haemopis sanguisuga using glass microelectrodes and input membrane resistance (IMR) was measured by injecting hyperpolarizing current pulses through these electrodes. Results show that the excitatory effect 2,4-DABA elicits on neurons’ membrane potential is dependent on sodium ions. Depolarizing effect of 5·10−3 mol/L 2,4-DABA in sodium-free solution was significantly diminished by 91% reducing it to 3.26 ± 0.62 mV and its two-stage nature was abrogated. In addition to being sodium-dependent, the depolarization of membrane potential induced by this amino acid is coupled with an increase of membrane permeability, as 2,4-DABA decreases IMR by 8.27 ± 1.47 MΩ (67.60%). Since present results highlight the role of sodium ions, we investigated the role of two putative sodium-dependent mechanisms in 2,4-DABA-induced excitatory effect – activation of ionotropic glutamate receptors and the electrogenic transporter for neutral amino acids. Excitatory effect of 5·10−3 mol/L 2,4-DABA was partially blocked by 10-5 mol/L 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) a non-NMDA receptor antagonist as the first stage of membrane depolarization was significantly reduced by 2.59 ± 0.98 mV (40%), whilst second stage remained unaltered. Moreover, involvement of the sodium-dependent transport system for neutral amino acids was investigated by equimolar co-application of 5·10−3 mol/L 2,4-DABA and L-alanine, a competitive inhibitor of this transporter. Although L-alanine exhibited no effect on the first stage of membrane depolarization elicited by 2,4-DABA, it substantially reduced the second stage (the overall membrane depolarization) from 39.63 ± 2.22 mV to 16.28 ± 2.58 mV, by 58.92%. We therefore propose that the electrophysiological effect of 2,4-DABA on Retzius neurons is mediated by two distinct mechanisms, i.e. by activation of ionotropic glutamate receptor that initiates the first stage of membrane depolarization followed by the stimulation of an electrogenic sodium-dependent neutral amino acid transporter, leading to additional influx of positive charge into the cell and the second stage of depolarization.”

The paper acknowledges CYANOCOST.

Reference:

Svetolik Spasic, Marija Stanojevic, Jelena Nesovic Ostojic, Sanjin Kovacevic, Jasna Todorovic, Marko Dincic, Vladimir Nedeljkov, Milica Prostran, Srdjan Lopicic (2020).
Two distinct electrophysiological mechanisms underlie extensive depolarization elicited by 2,4 diaminobutyric acid in leech Retzius neurons. Aquatic Toxicology 220, 105398.
https://doi.org/10.1016/j.aquatox.2019.105398.

 

Frontiers topic: Global Intensification of Cyanobacterial Blooms: The Driving Forces and Mitigation Approaches

This Frontiers Research Topic presents research papers and reviews that explore novel approaches expanding our understanding of the development of toxic phytoplankton blooms and their immense performance in a changing environment, with particular focus on Microcystis sp. It aims to address various aspects of cyanobacterial blooms including the following:

• abiotic and biotic drivers of cyanobacteria blooms

• biological role of secondary metabolites, including cyanotoxins, in the bloom’s lifecycle,

• allelopathic and info-chemical interactions between microorganisms involved in toxic blooms,

• competition in host/parasite interactions, including cy-anophages,

• novel strategies for mitigation of cyanobacterial blooms.

Topic Editors:

Aaron Kaplan, Hebrew University of Jerusalem, Israel),
Rainer Kurmayer, University of Innsbruck, Austria,
Assaf Sukenik, Kinneret Limnological Laboratory, Israel Oceanographic and Limnological Research, Leon H. Charney School of Marine Sciences, University of Haifa, Migdal, Israel.

Deadline for submission of abstracts: 01 April 2020.

Link to the webpage of this Frontiers Topic

 

Special Issue “Selected Papers from the 11th International Conference on Toxic Cyanobacteria” – Toxins

Dear Colleagues,

The International Conference on Toxic Cyanobacteria is a periodic summit of an international community focusing on the study of cyanotoxins and toxic cyanobacteria. The next ICTC 11 will be held in Kraków, Poland, 5–10 May, 2019.

The Local Organizing Committee agreed with Toxins to call for a Special Issue related to the research presented during ICTC 11. The submitted articles should contain recent and most important findings discussed during the conference including: the occurrence of toxic/invasive cyanobacteria in the context of climate changes; ecology of cyanobacteria with special emphasis on abiotic and biotic factors which regulate their growth and/or toxin production; physiological function, environmental significance and biotechnological application of secondary cyanometabolites; physiology and molecular biology of cyanobacteria; toxicity and harmful effects; risk identification and water management.

Link to the special issue: https://www.mdpi.com/journal/toxins/special_issues/Conference_Toxic_Cyanobacteria

Additional links to the conference which you may find useful: http://ictc11.org/special-issues/

On behalf of the Local Organizing Committee

Dr. Dariusz Dziga
Guest Editor

Special Issue “Harmful Cyanobacteria and Their Metabolites” – Applied Sciences

Dear Colleagues,

The ongoing eutrophication of aquatic ecosystems has increased cyanobacterial blooms and also intensified the problems caused by the blooms. Harmful cyanobacteria and their toxic metabolites are known to cause health concerns in humans, animals, and plants, and water-users continue to experience cyanobacterial hazards and nuisance in Europe and other parts of the world as evidenced by some recent events.

The Special Issue “Harmful Cyanobacteria and Their Metabolites” in the journal Applied Sciences has a wide scope and it is intended to address some of the gaps in our knowledge concerning the management of cyanobacterial problems. It deals with, e.g., the occurrence of harmful cyanobacteria, methods for the analysis of noxious cyanometabolites, fate/impact/health effects of cyanotoxins, as well as management measures related to harmful cyanobacteria.

Some examples of work relevant for the Special Issue includes manuscripts on toxic invasive cyanobacteria; occurrence of toxic cyanobacteria in less-studied environments; cyanobacterial adaptations to climate change especially in relation to toxin production; cyanobacterial production of taste and odor compounds; management of harmful cyanobacteria in protected ecosystems; exposure assessment and effects of cyanotoxins in aquatic and terrestrial organisms including humans; novel methods for monitoring and analysis of cyanotoxins; prevention and control measures for the elimination of cyanobacterial problems. Review papers promoting international initiatives for the management of cyanobacterial problems may also be considered if presented with a strong scientific rationale but the potential authors of such papers are encouraged to contact the Guest Editors in advance.

Dr. Jussi Meriluoto
Dr. Nada Tokodi
Guest Editors

Link to the webpage of the Issue.

Download the flyer of the Issue.

First study to show that microginins are genotoxic

Abstract from a paper by Ujvarosi et al. (2019), published in Chemospere :

Microginins (MGs) are bioactive metabolites mainly produced by Microcystis spp., (Cyanobacteria) commonly found in eutrophic environments. In this study, the cytotoxic and genotoxic activities of four MG congeners (MG FR3, MG GH787, cyanostatin B, MGL 402) and a well characterized cyanobacterial extract B-14-01 containing these metabolites were evaluated in the human hepatocellular carcinoma (HepG2) cell line. The cytotoxicity was measured with the MTT assay, while genotoxicity was studied with the comet, γH2AX and cytokinesis block (CBMN) micronucleus assays. The viability of cells after 24 h was significantly affected only by the extract, whereas after 72 h a concentration dependent decrease in cell proliferation was observed for the extract and tested microginins, with MGL 402 being the most potent and MG FR3 the least potent congener. The extract and all tested congeners induced DNA strand breaks after 4 and 24 h exposure. The most potent was the extract, which induced concentration and time dependent increase in DNA damage at concentrations ≥0.01 μg mL−1. Among microginins the most potent was MGL 402 (increase in DNA strand breaks at ≥ 0.01 μg mL−1) and MG FR3 was the least potent (increase in DNA strand breaks at ≥ 1 μg mL−1). However, no induction of DNA double strand breaks was observed after 24 and 72-h exposure to the cyanobacterial extract or MGs. Induction of genomic instability was observed in cells exposed to MG GH787, cyanostatin B and the extract B-14-01. This study is the first to provide the evidence that microginins exert genotoxic activity.

The paper is a product of joined research by groups in Slovenia and Hungary and features CYANOCOST members Bojana Zegura, Gabor Vasas, Klara Hercog, Metka Filipic. The authors acknowledge CYANOCOST.

Reference:

Andrea Zsuzsanna Ujvárosi, Klara Hercog, Milán Riba, Sándor Gonda, Metka Filipič, Gábor Vasas, Bojana Žegura (2019). “The cyanobacterial oligopeptides microginins induce DNA damage in the human hepatocellular carcinoma (HepG2) cell line”, Chemosphere, Volume 240,  https://doi.org/10.1016/j.chemosphere.2019.124880.

 

New marine cyanobacteria species found by Cyanolab in Aegean sea

A new paper by Konstantinou et al. from Cyanolab AUTH (Head: Dr. Spyros Gkelis), published in Journal of Phycology. The authors propose a novel marine genus Leptothoe gen. nov. and describe three new sponge-associated species:  Le. sithoniana, Le. kymatousa, and Le.  spongobia, based on a combination of molecular, chemical and morphological approach. The new sponge-associated Leptothoe species show distinct characters compared to other marine Leptolyngbyaceae, reinforcing the investigation of cyanobacterial diversity associated with sponges. Interestingly, Leptothoe spongobia TAU-MAC 1115 isolated from the sponge Acanthella acuta was shown to produce microcystin-RR indicating that microcystin production among marine cyanobacteria could be more widespread than previously determined.

Reference:

Konstantinou, D., Voultsiadou, E., Panteris, E., Zervou, S. K., Hiskia, A., & Gkelis, S. (2019). Leptothoe, a new genus of marine cyanobacteria (Synechococcales) and three new species associated with sponges from the Aegean Sea. Journal of phycology.  https://doi.org/10.1111/jpy.12866

 

Special Issue”Recent Developments in LC-MS of Algal Toxins: Present and Future Challenges”- Toxins

The combination of liquid chromatography with mass spectrometry (LC-MS) is a valuable tool for the determination of algal toxins contained at trace levels in complex matrices thanks to its high sensitivity, selectivity and ability to deal with the structural diversity and labile nature of the toxins. Targeted LC tandem MS (LC-MS/MS) approaches are already efficiently employed worldwide to monitor toxin distribution in the environment and in the food chain. At the same time, untargeted approaches based on  high resolution MS (LC-HRMS) have generally disclosed the presence of a much higher number and types of toxins and made straightforward elucidation of the gross structure of the unknowns based on the interpretation of their fragmentation patterns.

In view of the plethora of LC-MS/MS and LC-HRMS methods that have been developed so far, the need exists for critical reviews that, besides summarizing the methodologies for determination of each toxin-group, single out the main challenges to be addressed in the next future for marine, freshwater and fish-killing toxins. Collaborative efforts among scientists are strongly encouraged both in the field of the regulated toxins in EU and the emerging ones to build the rational basis for inter-laboratory validation trials, where needed. Original research articles reporting LC-MS based identification of emerging issues for water and food safety potentially associated with climate change as well as recent advancements in LC-MS data acquisition and treatment (On-line SPE-LC-MS, 2D-LC-MS, Metabolomics, among others) will be also included in this Special Issue.

More information can be found at: https://www.mdpi.com/journal/toxins/special_issues/lcms_Algal

Deadline for manuscript submissions is 31 December 2019

Guest Editors: Carmela Dell’Aversano and Luciana Tartaglione, Department of Pharmacy, University of Napoli Federico II

 

Special Issue “Biological Role of Cyanotoxins: Experimental and In-Field Evidence” -Toxins

Dear Colleagues,

Cyanobacteria are an ancient lineage of oxygenic photosynthetic bacteria found in a broad range of habitats, from soil to oceans, where they play important roles in the global nitrogen and carbon cycles. They are known for the toxic blooms they form in fresh water bodies around the world and the production of toxins, posing a threat to human and environmental health. Despite the tremendous effort to understand the biosynthesis, toxicity, and occurrence of cyanobacteria secondary metabolites, the biological role of these compounds still remains relatively unknown.  Various hypotheses in this regard have been put forward, encompassing both intracellular effects such as nutrient storage, light adaptation, and protection against oxidative stress, and extracellular functions including quorum sensing, allelopathic interactions, nutrient acquisition, colony formation, and grazing defense. The existing evidence on the potential role of cyanotoxins is mostly based on experimental studies and require further confirmation by in-field observations.

This Special Issue is destined to gather reviews, original experimental papers, and short notes reporting findings on experimental and in-field observations that aim to advance our understanding of the biological role of cyanotoxins.

Dr. Spyros Gkelis
Dr. Piotr Rzymski
Guest Editors

Deadline for manuscript submissions: 31 December 2019

Special issue webpage.

Frontiers Research Topic: Impact of Mycotoxins, Cyanotoxins and Phycotoxins in Food Sustainability

From the webpage of the Frontiers Research Topic:

A sustainable food system is insecure if toxins are a threat. There are three types of natural non-proteinaceous toxins that compromise reliability of food systems: cyanotoxins for freshwater aquatic products, phycotoxins for seafood, and mycotoxins mainly for cereals (also for other plant-based foods and food-products of animal origin).

This Research Topic aims to focus on several knowledge gaps that require in-depth research, with an emphasis on new or emerging toxins recently appearing due to global warming and international trade. In this context, several important issues related to toxins stand out for which new information and scientific evidence should be provided. These issues include: monitoring and analytical challenges (including the requirement for certified reference materials), the need for better understanding of toxin mode of action and toxicology, as well as the need to improve risk assessment, and the development of novel mitigation strategies.

We invite scientists from these relevant fields to contribute to this exciting area of research that combines pharmacology, analytical chemistry, toxicology, mycology, phycology, and food safety.

Topic Editors : Luis M. Botana, Panagiota Katikou, Maria J. Sainz, Alison Robertson

View details about this Research Topic here.