Anatoxin-a and a previously unknown toxin in Anabaena planctonica from blooms found in Lake Mulargia (Italy)

Bruno, Marco; Barbini, Danilo Attard; Pierdominici, Elio; Serse, A.P.; Ioppolo, A.

doi:10.1016/0041-0101(94)90089-2

Cited by 57 publications

(29 citation statements)

References 7 publications

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“…In Italy, reports of ATX are quite rare, refer ring exclusively to environmental samples (e.g., Cerasino and Salmaso, 2012). The production of ATX was associated with blooms or higher development of Anabaena planctonica (Doli chospermum planctonicum) (Bruno et al, 1994), Anabaena crassa (D. crassum) (Messineo et al, 2009) and "a peculiar P. rubescens population" (Viaggiu et al, 2004;Messineo et al, 2009). How ever, the ability of isolated populations of these species to produce ATX in culture conditions was not confirmed.…”

Section: Discussionmentioning

confidence: 99%

Anatoxin-a producing Tychonema (Cyanobacteria) in European waterbodies

et al. 2015

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Keywords:Anatoxin a Tychonema Cell quotaPolyphasic approach Phylogenetic analysis European waterbodies a b s t r a c tIn order to identify the cyanobacterial species responsible of anatoxin a (ATX) production in Lake Garda (Northern Italy), an intensive isolation and culturing of filamentous cyano bacteria were established since 2014 from environmental samples. In this work, we report a detailed account of the strategy adopted, which led to the discovery of a new unexpected producer of ATX, Tychonema bourrellyi. So far, this species is the first documented example of cultured Oscillatoriales able to produce ATX isolated from pelagic freshwater ecosys tems. The isolated filaments were identified adopting a polyphasic approach, which included microscopic species identification, genetic characterisation and phylogenetic analyses based on 16S rRNA genes. The taxonomic identification was further confirmed by the high (>99%) rbcLX sequence similarities of the T. bourrellyi strains of Lake Garda with those deposited in DNA sequence databases. More than half of the isolates were shown to produce a significant amount of ATX, with cell quota ranging between 0.1 and 2.6 mg mm 3 , and 0.01 and 0.35 pg cell 1 . The toxic isolates were tested positive for anaC of the anatoxin a synthetase (ana) gene cluster. These findings were confirmed with the discovery of one ATX producing T. bourrellyi strain isolated in Norway. This strain and a further non ATXproducing Norwegian Tychonema bornetii strain tested positive for the presence of the anaF gene of the ana gene cluster. Conversely, none of the Italian and Norwegian Tychonema strains were positive for microcystins (MCs), which was also confirmed by the absence of mcyE PCR products in all the samples analysed. This work suggests that the only reliable strategy to identify cyanotoxins producers should be based on the isolation of strains and their identification with a polyphasic approach associated to a concurrent metabolomic profiling.

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Section: Discussionmentioning

confidence: 99%

Anatoxin-a producing Tychonema (Cyanobacteria) in European waterbodies

et al. 2015

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“…For a more accurate risk assessment a complete molecular profiling of the toxic compounds is required, but unfortunately this approach is laborious and costly. Several papers have been published about the occurrence of toxic cyanobacteria in Italian fresh water (Aktan et al 2009, Barone et al 2010, Bruno et al 1994, Manganelli et al 2010, Messineo et al 2006, Sechi and Lugliè 1992, Viaggiu et al 2004. These authors have shown that potentially toxic blooms can occur not only in eutrophic water basins but also in oligotrophic ones.…”

Section: Introductionmentioning

confidence: 99%

Diversity and distribution of cyanobacterial toxins in the Italian subalpine lacustrine district

Cerasino

Salmaso

2012

Oceanological and Hydrobiological Studies

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Nine lakes (Garda, Maggiore, Como, Iseo, Lugano, Idro, Pusiano, Ledro, and Levico) located in the Italian subalpine lacustrine district were chosen for a comparative study of the diversity and distribution of cyanobacterial toxins. All nine lakes are known to host different toxic cyanobacteria, mainly Planktothrix rubescens. An analytical protocol has been used, based on LC-MS technique, for determining 20 different toxins (14 microcystins, 2 nodularins, anatoxin-a and 3 cylindrospermopsins). In the investigation, microcystins were found in all lakes on all sampling dates. Anatoxin-a could be detected in 6 lakes, but it was only present in 4 lakes on all sampling dates (lakes Garda, Iseo, Como, and Maggiore). Nodularins and cylindrospermopsins were not detected at all. The number of microcystins detected in the survey was 9, but 4 were the most abundant (dmRR, YR, dmLR, and LR); they were differently distributed among the lakes, thus providing each lake a unique toxic potential. Statistical analysis showed positive * Corresponding Author e-mail: leonardo.cerasino@iasma.it correlations between total microcystin concentrations and eutrophication indicators and also between anatoxin-a concentrations and water temperature, suggesting that anthropic and climate-related stressors can have different impacts on the presence of different cyanotoxins.

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“…The LD 50 for ANTX and HANTX ranges between 200 and 250 mg kg 21 i.p., mouse (Carmichael & Gorham, 1978;Skulberg et al, 1992). Animal poisonings by ingestion of ANTX/HANTX-producing cyanobacteria in lakes and ponds have been well documented, and are generally caused by planktonic species of Anabaena or Aphanizomenon (Bruno et al, 1994;Sivonen & Jones, 1999). However, good evidence for a similar incident due to a benthic filamentous cyanobacterium of the genus Oscillatoria has also been obtained (Edwards et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Neurotoxins in axenic oscillatorian cyanobacteria: coexistence of anatoxin-a and homoanatoxin-a determined by ligand-binding assay and GC/MS

et al. 2005

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Two neurotoxic alkaloids, anatoxin-a and its homologue homoanatoxin-a, were purified from the filamentous cyanobacteria Oscillatoria sp. strain 193 (PCC 9240) and Oscillatoria formosa NIVA CYA-92 (PCC 10111), respectively, and characterized by mass spectrometry. Biological activity was determined by examining the capacity of the toxins to competitively inhibit the binding of radiolabelled bungarotoxin to acetylcholine receptors, using post-synaptic membrane fractions of Torpedo electric tissue. Inhibition was concentration dependent, with a K i of 5?4±1?1610 "8 M for anatoxin-a and 7?4±0?9610 "8 M for homoanatoxin-a. Their high affinities for the nicotinic cholinergic receptors were exploited to adapt the radioligand-binding assay for routine detection of this class of neurotoxins directly in low-molecular-mass cell extracts of cyanobacteria. Confirmation of the results and toxin identification were achieved by coupled gas chromatography-mass spectrometry (GC/MS). Seventy-six axenic strains, representative of 13 genera, were analysed. Five strains of the genus Oscillatoria, hitherto unknown for their toxicity, inhibited bungarotoxin binding. GC/MS revealed that Oscillatoria sp. strains PCC 6407, PCC 6412 and PCC 9107 synthesized exclusively anatoxin-a, whereas both anatoxin-a and homoanatoxin-a were produced by strain PCC 9029. Oscillatoria sp. strain PCC 6506, an isolate co-identic with strain PCC 9029, also produced both neurotoxins, but their respective presence depended upon growth conditions. The latter results suggest that regulatory differences in at least some of the cyanobacterial strains may account for the preferential synthesis of only one of the two neurotoxins or for their simultaneous occurrence. INTRODUCTIONWorldwide proliferation of cyanobacterial blooms constitutes a serious environmental and economic problem that menaces wildlife and human health. Bloom development, a phenomenon related to water eutrophication, is favoured by the ability of planktonic cyanobacteria to synthesize gas vesicles that allow them to float to the surface layers of the water column. The massive growth and accumulation of cyanobacteria greatly impair food-web dynamics and the physico-chemical factors inside a given aquatic ecosystem. Moreover, many cyanobacteria are able to produce potent hepatotoxins such as microcystin, cylindrospermopsin and nodularin, and/or neurotoxins such as anatoxin-a, homoanatoxin-a, anatoxin-a(s) and saxitoxin (Carmichael, 1994;Sivonen & Jones, 1999).Anatoxin-a (ANTX) (2-acetyl-9-azabicyclo[4.2.1]non-2-ene) and its methylene homologue homoanatoxin-a (HANTX) (2-(propan-1-oxo-1-yl)-9-azabicyclo[4.2.1]non-2-ene) (Devlin et al., 1977;Skulberg et al., 1992), are lowmolecular-mass bicyclic secondary amines synthesized by some planktonic and benthic strains of the genera Anabaena, Oscillatoria, Aphanizomenon and Cylindrospermum (Sivonen et al., 1989(Sivonen et al., , 1990. At nanomolar levels, ANTX is a specific cholinergic agonist whose potency relies upon its high affinity for the nicotinic acet...

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Anatoxin-a and a previously unknown toxin in Anabaena planctonica from blooms found in Lake Mulargia (Italy)

Cited by 57 publications

References 7 publications

Anatoxin-a producing Tychonema (Cyanobacteria) in European waterbodies

Anatoxin-a producing Tychonema (Cyanobacteria) in European waterbodies

Diversity and distribution of cyanobacterial toxins in the Italian subalpine lacustrine district

Neurotoxins in axenic oscillatorian cyanobacteria: coexistence of anatoxin-a and homoanatoxin-a determined by ligand-binding assay and GC/MS

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