In Vitro Toxicological Screening of Stable and Senescing Cultures of Aphanizomenon, Planktothrix, and Raphidiopsis

Abstract

Toxicity of cyanobacteria is the subject of ongoing research, and a number of toxic metabolites have been described, their biosynthesis pathways have been elucidated, and the mechanism of their action has been established. However, several knowledge gaps still exist, e.g., some strains produce hitherto unknown toxic compounds, while the exact dynamics of exerted toxicity during cyanobacterial growth still requires further exploration. Therefore, the present study investigated the toxicity of extracts of nine freshwater strains of Aphanizomenon gracile, an Aphanizomenon sp. strain isolated from the Baltic Sea, a freshwater strain of Planktothrix agardhii, and two strains of Raphidiopsis raciborskii obtained from 25- and 70-day-old cultures. An in vitro experimental model based on Cyprinus carpio hepatocytes (oxidative stress markers, DNA fragmentation, and serine/threonine protein activity) and brain homogenate (cholinesterase activity) was employed. The studied extracts demonstrated toxicity to fish cells, and in general, all examined extracts altered at least one or more of considered parameters, indicating that they possess, to some degree, toxic potency. Although the time from which the extracts were obtained had a significant importance for the response of fish cells, we observed strong variability between the different strains and species. In some strains, extracts that originated from 25-day-old cultures triggered more harmful effects on fish cells compared to those obtained from 70-day-old cultures, whereas in other strains, we observed the opposite effect or a lack of a significant change. Our study revealed that there was no clear or common pattern regarding the degree of cyanobacterial bloom toxicity at a given stage of development. This means that young cyanobacterial blooms that are just forming can pose an equally toxic threat to aquatic vertebrates and ecosystem functioning as those that are stable or old with a tendency to collapse. This might be largely due to a high variability of strains in the bloom.

Insight into Unprecedented Diversity of Cyanopeptides in Eutrophic Ponds Using an MS/MS Networking Approach

“…CNPs, such as aeruginosins, microginins, cyanopeptolins, anabaenopeptilides, microviridins, anabaenopeptins, and nostophycins, with numerous structural variants are regularly found in cyanobacterial blooms [ 13 , 16 , 17 , 18 ]. Recent findings have suggested that metabolomic profiles consisting of different CNPs affect the cohabiting invertebrates and fish populations differently [ 19 , 20 , 21 ], underlining the need for the expansion of the number of regularly monitored and studied CNPs.…”

Insight Into Unprecedented Diversity of Cyanopeptides in Eutrophic Ponds Using a MS/MS Networking Approach

“…CNPs, such as aeruginosins, microginins, cyanopeptolins, anabaenopeptilides, microviridins, anabaenopeptins , and nostophycins with numerous structural variants are regularly found in the cyanobacterial blooms [13,[16][17][18]. Recent findings suggested that metabolomic profiles consisting of different CNPs affect differently, the cohabiting invertebrates and fish populations [19][20][21], underlining the need for expansion of the number of regularly monitored and studied CNPs.…”

Interplay of Nutrients, Temperature, and Competition of Native and Alien Cyanobacteria Species Growth and Cyanotoxin Production in Temperate Lakes

“…Possibly other factors or metabolites of A. gracile may significantly affect P. agardhii growth. It was found that an exudate of A. gracile had a cytotoxic effect on human neutrophiles [ 59 ] and the species extracts can induce cholinesterase activity in the fish brain homogenate [ 60 ]. More studies should be conducted to disclose the mechanisms of the interactions among the studied species.…”