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.


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.


New research shows that 2,4-DABA induces irreversible functional changes in neurons.

From the abstract of a recent paper by Spacic et al. in Aquatic Toxicology:

“In this paper we present, for the first time, a detailed account of electrophysiological effects of 2,4-diaminobutyric acid (2,4-DABA). 2,4-DABA is a neurotoxic non-protein amino acid produced by Cyanobacteria with a possible link to neurodegenerative disorders in animals and humans. Intracellular recordings were performed on Retzius nerve cells of the leech Haemopis sanguisuga using glass microelectrodes filled with 3 mol/L KCl. Our results show that 2,4-DABA is an excitatory amino acid, causing membrane depolarization in a concentration dependent manner. The most prominent depolarizations of 39.63 ± 2.22 mV and 47.05 ± 4.33 mV, induced by 5 × 10−3 and 10−2 mol/L 2,4-DABA respectively, are several times larger than maximal depolarizations induced by either Glutamate, Aspartate, β-N-methylamino-alanine (BMAA) or β-N-oxalylamino-alanine (BOAA) on our model. These 2,4-DABA induced depolarizations evolve through two distinct stages, which is a novel phenomenon in electrical cell activity upon application of an excitatory amino acid, at least on our model. Involvement of two separate mechanisms, suggested by the two stage phenomenon, is discussed in the paper. We also provide evidence that 2,4-DABA induces irreversible functional disturbances in neurons in a concentration dependent manner, since only half of the cells recovered normal electrical activity after application of 5 × 10−3 mol/L 2,4-DABA, and none recovered after application of 10−2 mol/L 2,4-DABA. Effects of both L-2,4-DABA and DL-2,4-DABA were tested and are not significantly different.”


S. Spasic, M. Stanojevic, J. Nesovic Ostojic, S. Kovacevic, M. Prostran, S. Lopicic (2018).
Extensive depolarization and lack of recovery of leech Retzius neurons caused by 2,4 diaminobutyric acid. Aquatic Toxicology, Volume 199, Pages 269-275.

The paper acknowledges CYANOCOST.

Cyanobacterial effects in Lake Ludoš, Serbia – Is preservation of a degraded aquatic ecosystem justified?

From the abstract of a recent paper by Tokodi et al. (2018), in Science of the Total Environment:

Cyanobacteria are present in many aquatic ecosystems in Serbia. Lake Ludoš, a wetland area of international significance and an important habitat for waterbirds, has become the subject of intense research interest because of practically continuous blooming of cyanobacteria. Analyses of water samples indicated a deterioration of ecological condition and water quality, and the presence of toxin-producing cyanobacteria (the most abundant Limnothrix redekei, Pseudanabaena limnetica, Planktothrix agardhii and Microcystis spp.). Furthermore, microcystins were detected in plants and animals from the lake: in macrophyte rhizomes (Phragmites communis, Typha latifolia and Nymphaea elegans), and in the muscle, intestines, kidneys, gonads and gills of fish (Carassius gibelio). Moreover, histopathological deleterious effects (liver, kidney, gills and intestines) and DNA damage (liver and gills) were observed in fish. A potential treatment for the reduction of cyanobacterial populations employing hydrogen peroxide was tested during this study. The treatment was not effective in laboratory tests although further in-lake trials are needed to make final conclusions about the applicability of the method. Based on our observations of the cyanobacterial populations and cyanotoxins in the water, as well as other aquatic organisms and, a survey of historical data on Lake Ludoš, it can be concluded that the lake is continuously in a poor ecological state. Conservation of the lake in order to protect the waterbirds (without urgent control of eutrophication) actually endangers them and the rest of the biota in this wetland habitat, and possibly other ecosystems. Thus, urgent measures for restoration are required, so that the preservation of this Ramsar site would be meaningful.


Nada Tokodi, Damjana Drobac, Jussi Meriluoto, Jelena Lujić, Zoran Marinović, Tamara Važić, Sonja Nybom, Jelica Simeunović, Tamara Dulić, Gospava Lazić, Tamaš Petrović, Branka Vuković-Gačić, Karolina Sunjog, Stoimir Kolarević, Margareta Kračun-Kolarević, Gordana Subakov-Simić, Branko Miljanović, Geoffrey A. Codd, Zorica Svirčev,
Cyanobacterial effects in Lake Ludoš, Serbia – Is preservation of a degraded aquatic ecosystem justified?. Science of The Total Environment, Volume 635, 2018, Pages 1047-1062,


Workshop “Cyanotoxins -toxicity, health and environmental impact”, Novi Sad, Serbia,13 -14 July, 2017.

Invitation from Co-Chair of the Organizing Committee, Dr. Jelica Simeunovic:

“On behalf of the Organizing Committee, I cordially invite you to attend the Workshop entitled “Cyanotoxins -toxicity, health and environmental impact”, to be held in Novi Sad, Serbia from 13 to 14 July, 2017.

The meeting will be organized in the framework of the SCOPES project as a contribution to further investigation of toxic cyanobacteria, cyanotoxins and their impacts on human, animal and environmental health.

The workshop promises to be an excellent opportunity to discuss the current progress in cyanotoxins research and to present results that can change our approach to resolving the problems of cyanotoxin occurrence in the environment, especially in freshwaters.

Hopefully, the workshop will promote active scientific exchange and communication between researchers and practitioners from Serbia and worldwide who will share with us the recent achievements  in cyanobacteria and cyanotoxin research.

In the attachment you will find the Announcement  with the necessary information and instructions for abstract submission, as well as the Registration form . If you plan to participate at the Workshop, please fill-in the registration form that will help us in organizing the meeting. Deadline for sending the registration form for participation is May 20th, 2017.”

With kind regards and looking forward to seeing you at the Workshop,
Co-Chair of the Organizing Committee
dr. Jelica Simeunović

Workshop Novi Sad 2017

Jussi Meriluoto presents “The Uzice case” at the Muséum National d’Histoire Naturelle, Paris

Jussi Meriluoto gives a seminar titled “The Uzice case” on 19 January 2017 at the Bio-organic Mass-Spectrometry Technical Platform of the Muséum National d’Histoire Naturelle in Paris.


The Uzice case. (J. Meriluoto, Z. Svircev). Abstract:

An intensive bloom of the cyanobacterium Planktothrix rubescens was observed in the Vrutci reservoir in December 2013. The blooming reservoir served as the drinking water source for the city of Užice, Serbia, with 70,000 inhabitants. Filaments of the cyanobacterium were found in the treated water and there were complaints about discoloured tap water. The MC-LR concentration in a drinking water sample was below the WHO provisional guideline value (1 µg/L) according to analyses provided by the Institute of Public Health Serbia. Despite this, the Sanitary Inspectorate of the Republic of Serbia decided to ban the use of tap water for drinking and cooking purposes to protect the health of the inhabitants of Užice. The situation soon resulted in unrest among the citizens. The toxicity of the cyanobacterial biomass was first shown by A. salina bioassays. Microcystin(s) were later detected by LC-MS/MS in samples of the reservoir and tap water, and in fish captured from the reservoir. Data about the water use and the health of the inhabitants were collected with the help of a questionnaire which clearly indicated a number of health issues. An epidemiological investigation also showed an elevated occurrence of digestive tract and skin diseases compared to earlier years, possibly as a result of exposure to the cyanobacterial material/metabolites. Based on the evidence found, it is likely that a cyanobacterial bloom occurred in the reservoir already before 2013. Lessons from the Užice case are many. The presentation discusses i) the importance of interaction between academia and authorities, ii) proper monitoring of cyanobacterial hazards, iii) the necessity of adequate information and advice to the general public, iv) guidelines and legislation, and v) collection of exposure and health data complementary to analytical results. Further, the authors would like to underline the recurrent role of Planktothrix sp. in drinking water quality problems.

Further reading:

Svirčev, Z., D. Drobac, N. Tokodi, D. Đenić, J. Simeunović, A. Hiskia, T. Kaloudis, B. Mijović, S. Šušak, M. Protić, M. Vidović, A. Onjia, S. Nybom, T. Važić, T. Palanački Malešević, T. Dulić, D. Pantelić, M. Vukašinović & J. Meriluoto (2017) Lessons from the Užice case: how to complement analytical dataHandbook of Cyanobacterial Monitoring and Cyanotoxin Analysis (J. Meriluoto, L. Spoof & G. A. Codd, Eds.), Chichester: Wiley.

Svirčev, Z., D. Drobac, N. Tokodi, B. Mijović, G. A. Codd & J. Meriluoto (2017) Toxicology of microcystins with reference to cases of human intoxications and epidemiological investigations of exposures to cyanobacteria and cyanotoxins – Archives of Toxicology, pp.1-30,  doi:10.1007/s00204-016-1921-6