Revealing Toxin Signatures in Cyanobacteria: Report of Genes Involved in Cylindrospermopsin Synthesis from Saxitoxin-Producing <i>Cylindrospermopsis raciborskii</i>

Abstract

Cyanotoxins are distinctive molecules in Cyanobacteria whose evolutionary origin, radiation and ecological role are still controversial. The cyanobacterium Cylindrospermopsis raciborskii is alternately capable of producing two types of potent toxins, cylindrospermopsin (CYN) or saxitoxin and analogues (SAX). It has been proposed that this species spread to all continents early in its evolutionary history and biogeographical differences in toxin production are found between populations. Most reports indicate that American strains are able to produce SAX but not CYN, while Australian strains are described to produce CYN but not SAX. Here we describe the presence of three genes belonging to the cylindrospermopsin cluster (cyr), cyrA, cyrB and cyrC, in two SAX producing South American C. raciborskii strains, MVCC14 and MVCC19, which due to their differences in morphology, growth preferences, SAX production and genetic context are defined as different ecotypes. No CYN production was detected in either strain (by ELISA) after growth under nitrogen replete or nitrogen-free nutrient conditions. Phylogenetic analyses of cyrA, cyrB and cyrC partial sequences from both strains showed high similarity (>99%) with CYN genes belonging to C. raciborskii strains from Australia and Germany and to Aphanizomenon strains. This is the first report of the presence of cyr genes in strains known to produce only SAX.

Genomic and Genotypic Characterization of Cylindrospermopsis raciborskii: Toward an Intraspecific Phylogenetic Evaluation by Comparative Genomics

“…Vestiges of cyr genes were found in the genomes of South American STX-producing C. raciborski strains. However, the annotated gene fragments were different from the gene fragments amplified by PCR using specific primers in previous studies ( Hoff-Risseti et al, 2013 ; Piccini et al, 2013 ). No vestiges of sxt genes were found in the genomes of the CYN-producing strains.…”

Allochthonous planktonic algae recorded during the last 25 years in Bulgaria and their possible dispersal agents

“…Among the species, which easily could be outlined as aliens in Bulgarian algal flora, are the pantropical Cylindrospermopsis raciborskii (Woloszynska) Seenayya et Subba Raju, well-known as invasive in most of the European countries and in America (e.g., all citations from Padisák, 1997to Piccini et al, 2013 and the debatable Raphidiopsis mediterranea Skuja, described from the Mediterranean lake Kastoria (Komárek, 2014). Morphological and phylogenetic evidence suggest that this taxon represents a nonheterocystous part of the life cycle of C. raciborskii (e.g., Moustaka-Gouni et al, 2009 and it has been affiliated to the same functional group (S N ) where C. raciborskii belongs (Padisák et al, 2009).…”

Influence of UV-B radiation on the fitness and toxin expression of the cyanobacterium Cylindrospermopsis raciborskii

“…1, from Uruguay, were selected. Cylindrospermopsis strains were different ecotypes based on their morphology and toxin production (MVCC19: saxitoxin producer, LB2897: non-toxic and CYP011 K: cylindrospermopsin producer) (Piccini et al, 2011(Piccini et al, , 2013. Cultures were kept in BG11 modified medium (Ivanikova et al, 2007).…”

“…raciborskii can produce two potent toxins, cylindrospermopsin (cytotoxin) or saxitoxin and its derivatives (neurotoxins), but may also be non-toxic (Haande et al, 2008;Piccini et al, 2011). A current hypothesis suggests there is link between the geographical distribution of C. raciborskii strains and the toxins they produce (Sinha et al, 2012;Piccini et al, 2013;Wood et al, 2014). However, it is still not clear what environmental factors are involved in promoting toxin production, and the biological role of toxins remains controversial .…”