Cyanobacterial cytotoxicity versus toxicity to brine shrimp Artemia salina.

Heterocytous cyanobacteria from various habitats were screened for toxicity to brine shrimp Artemia salina and the murine lymphoblastic cell line Sp/2 in order to compare these two testing models for evaluation of risk posed by cyanobacteria to human health. Methanol extracts of biomass and cultivation media were tested for toxicity and selected extracts were fractionated to determine the active fraction. We found a significant toxic effect to A. salina and to Sp/2 cells in 5.2% and 31% of studied extracts, respectively. Only 8.6% of the tested strains were highly toxic to both A. salina and the Sp/2 cell line, and only two of the tested strains were toxic to A. salina and not to the murine cell line. Therefore, it is likely that the toxic effect of cyanobacterial secondary metabolites mostly targets basal metabolic pathways present in mammal cells and so is not manifested in A. salina. We conclude that it is insufficient to monitor cytotoxicity of cyanobacteria using only the brine shrimp bioassay as was usual in the past, since cytotoxicity is a more frequent feature in cyanobacteria in comparison with toxicity to A. salina. A. salina toxicity test should not be used when estimating the possible health risk for humans. We suggest that in vitro mammal cells be used for these purposes.

POLYPHASIC CHARACTERIZATION OF DOLICHOSPERMUM SPP. AND SPHAEROSPERMOPSIS SPP. (NOSTOCALES, CYANOBACTERIA): MORPHOLOGY, 16S rRNA GENE SEQUENCES AND FATTY ACID AND SECONDARY METABOLITE PROFILES(1).

The genera Dolichospermum (Ralfs ex Bornet et Flahault) Wacklin, L. Hoffm. et Komárek and Sphaerospermopsis Zapomelová, Jezberová, Hrouzek, Hisem, K. Reháková et Komárk.-Legn. represent a highly diversified group of planktonic cyanobacteria that have been recently separated from the traditional genus Anabaena Bory ex Bornet et Flahault. In this study, morphological diversity, phylogeny of the 16S rRNA gene, production of fatty acids, and secondary metabolite profiles were evaluated in 33 strains of 14 morphospecies isolated from the Czech Republic. Clustering of the strains based on 16S rRNA gene sequences corresponded to wider groups of species in terms of morphology. The overall secondary metabolite and fatty acid profiles, however, were not correlated to each other and neither were they correlated to the 16S rRNA phylogeny nor the morphology of the strains. Nevertheless, a minor part of the detected secondary metabolites (19% of all compounds) was present only in close relatives and can be thus considered as autapomorphic features.

POLYPHASIC CHARACTERIZATION OF THREE STRAINS OF ANABAENA RENIFORMIS AND APHANIZOMENON APHANIZOMENOIDES (CYANOBACTERIA) AND THEIR RECLASSIFICATION TO SPHAEROSPERMUM GEN. NOV. (INCL. ANABAENA KISSELEVIANA)(1).

Occurrences of rare cyanobacteria Anabaena reniformis Lemmerm. and Aphanizomenon aphanizomenoides (Forti) Horecká et Komárek were recently detected at several localities in the Czech Republic. Two monoclonal strains of An. reniformis and one strain of Aph. aphanizomenoides were isolated from distant localities and different sampling years. They were characterized by a combination of morphological, genetic, and biochemical approaches. For the first time, partial 16S rRNA gene sequences were obtained for these morphospecies. Based on this gene, all of these strains clustered separately from other planktonic Anabaena and Aphanizomenon strains. They appeared in a cluster with Cylindrospermopsis Seenaya et Subba Raju and Raphidiopsis F. E. Fritsch et M. F. Rich, clustered closely together with two An. kisseleviana Elenkin strains available from GenBank. A new generic entity was defined (Sphaerospermum gen. nov., with the type species S. reniforme, based on the traditional species An. reniformis). These results contribute significantly to the knowledge base about genetic heterogeneity among planktonic Anabaena-like and Aphanizomenon-like morphospecies. Accordingly, the subgenus Dolichospermum, previously proposed for the group of planktonic Anabaena, should be revaluated. Secondary metabolite profiles of the An. reniformis and Aph. aphanizomenoides strains differed considerably from 17 other planktonic Anabaena strains of eight morphospecies isolated from Czech water bodies. Production of puwainaphycin A was found in both of the An. reniformis strains. Despite the relatively short phylogenetic distance from Cylidrospermopsis, the production of cylindrospermopsin was not detected in any of our strains.