Geographical Segregation of the Neurotoxin-Producing Cyanobacterium Anabaena circinalis

Abstract

Blooms of the cyanobacterium Anabaena circinalis are a major worldwide problem due to their production of a range of toxins, in particular the neurotoxins anatoxin-a and paralytic shellfish poisons (PSPs). Although there is a worldwide distribution of A. circinalis, there is a geographical segregation of neurotoxin production. American and European isolates of A. circinalis produce only anatoxin-a, while Australian isolates exclusively produce PSPs. The reason for this geographical segregation of neurotoxin production by A. circinalis is unknown. The phylogenetic structure of A. circinalis was determined by analyzing 16S rRNA gene sequences. A. circinalis was found to form a monophyletic group of international distribution. However, the PSP-and non-PSP-producing A. circinalis formed two distinct 16S rRNA gene clusters. A molecular probe was designed, allowing the identification of A. circinalis from cultured and uncultured environmental samples. In addition, probes targeting the predominantly PSP-producing or non-PSP-producing clusters were designed for the characterization of A. circinalis isolates as potential PSP producers.

An overview of diversity, occurrence, genetics and toxin production of bloom-forming Dolichospermum (Anabaena) species

“…Within the Dolichospermum genus, saxitoxin production has been only reported in D. circinalis (Anabaena circinalis) blooms in Australian freshwater systems, such as dams, weirs on rivers, and reservoirs (Beltran and Neilan, 2000). The gene cluster responsible for saxitoxin biosynthesis (genes sxtA-E and sxtG-X spanning 28 kbp) has been described for D. circinalis (Mihali et al, 2009) (Fig.…”

“…It has been estimated that about half of the cyanobacterial strains in culture collections have been misidentified (Komá rek and Anagnostidis, 1989). Several studies have cautioned against the over-emphasis on morphological characters for identification and taxonomic classification (Beltran and Neilan, 2000;Rajaniemi et al, 2005a,b;Zapomělová et al, 2007Zapomělová et al, , 2010b.…”

Occurrence and elimination of cyanobacterial toxins in two Australian drinking water treatment plants

“…PSPs are potent blockers of voltage-dependent sodium-channels and therefore restrict transmission between neurons. In contrast to the only PSPproducing Australian strains, European and American strains of Anabaena circinalis appear to exclusively synthesize anatoxins (Beltran and Neilan, 2000). In general, the genus Anabaena can produce MCs, PSPs and anatoxin-a with toxin contents of 2 mg/g dry weight (DW) for MCs (Rapala and Sivonen, 1998), 4.4 mg/g DW for PSPs (Velzeboer et al, 2000) and a remarkable 28 mg/g DW for anatoxin-a (Rapala and Sivonen, 1998).…”

Morphological characteristics and phylogenetic relationship of Anabaena species from Lakes Dianchi and Erhai, China

“…Beltran & Neilan (2000) found a close relationship between the A. flos-aquae AWQC112D strain and several A. circinalis strains, and reported that no other clone of A. flos-aquae except for this one from Australia has appeared in such a position. Our finding about strains DC-1, DC-2, and EH-1 adds new information on the distribution of A. flos-aquae strains and supports that there exist probably two branches of this morphotype (Beltran & Neilan, 2000). According to the phylogenetic analysis of 16S rRNA genes, strains EH-2, EH-3, and EH-4 were very close to the group which included some A. circinalis and A. crassa strains.…”