scholarly journals Diversity of cyanobacteria and cyanotoxins in Hartbeespoort Dam, South Africa

2014 ◽  
Vol 65 (2) ◽  
pp. 175 ◽  
Author(s):  
Andreas Ballot ◽  
Morten Sandvik ◽  
Thomas Rundberget ◽  
Christo J. Botha ◽  
Christopher O. Miles
Keyword(s):  
South African ◽  
Toxin Production ◽  
Cyanobacterial Species ◽  
Microcystis Blooms ◽  
Liquid Chromatography Tandem Mass ◽  
Mcye Gene ◽  
Microcystis Strain ◽  
Microcystin Production ◽  
Encoding Gene ◽  
Encoding Genes

The South African Hartbeespoort Dam is known for the occurrence of heavy Microcystis blooms. Although a few other cyanobacterial genera have been described, no detailed study on those cyanobacteria and their potential toxin production has been conducted. The diversity of cyanobacterial species and toxins is most probably underestimated. To ascertain the cyanobacterial composition and presence of cyanobacterial toxins in Hartbeespoort Dam, water samples were collected in April 2011. In a polyphasic approach, 27 isolated cyanobacterial strains were classified morphologically and phylogenetically and tested for microcystins (MCs), cylindrospermopsin (CYN), saxitoxins (STXs) and anatoxin-a (ATX) by liquid chromatography–tandem mass spectrometry (LC–MS/MS) and screened for toxin-encoding gene fragments. The isolated strains were identified as Sphaerospermopsis reniformis, Sphaerospermopsis aphanizomenoides, Cylindrospermopsis curvispora, Raphidiopsis curvata, Raphidiopsis mediterrranea and Microcystis aeruginosa. Only one of the Microcystis strains (AB2011/53) produced microcystins (35 variants). Forty-one microcystin variants were detected in the environmental sample from Hartbeespoort Dam, suggesting the existence of other microcystin producing strains in Hartbeespoort Dam. All investigated strains tested negative for CYN, STXs and ATX and their encoding genes. The mcyE gene of the microcystin gene cluster was found in the microcystin-producing Microcystis strain AB2011/53 and in eight non-microcystin-producing Microcystis strains, indicating that mcyE is not a good surrogate for microcystin production in environmental samples.

scholarly journals Two Polyketide Synthase-Encoding Genes Are Required for Biosynthesis of the Polyketide Virulence Factor, T-toxin, by Cochliobolus heterostrophus

2006 ◽  
Vol 19 (2) ◽  
pp. 139-149 ◽  
Author(s):  
Scott E. Baker ◽  
Scott Kroken ◽  
Patrik Inderbitzin ◽  
Thipa Asvarak ◽  
Bi-Yu Li ◽  
...  
Keyword(s):  
Polyketide Synthase ◽  
Toxin Production ◽  
Carbon Chain ◽  
Cochliobolus Heterostrophus ◽  
Maize Production ◽  
High Virulence ◽  
Encoding Gene ◽  
Corn Leaf Blight ◽  
Encoding Genes ◽  
Sequencing Procedure

Cochliobolus heterostrophus race T, causal agent of southern corn leaf blight, requires T-toxin (a family of C35 to C49 polyketides) for high virulence on T-cytoplasm maize. Production of T-toxin is controlled by two unlinked loci, Tox1A and Tox1B, carried on 1.2 Mb of DNA not found in race O, a mildly virulent form of the fungus that does not produce T-toxin, or in any other Cochliobolus spp. or closely related fungus. PKS1, a polyketide synthase (PKS)-encoding gene at Tox1A, and DEC1, a decarboxylase-encoding gene at Tox1B, are necessary for T-toxin production. Although there is evidence that additional genes are required for Ttoxin production, efforts to clone them have been frustrated because the genes are located in highly repeated, A+T-rich DNA. To overcome this difficulty, ligation specificity-based expression analysis display (LEAD), a comparative amplified fragment length polymorphism/gel fractionation/capillary sequencing procedure, was applied to cDNAs from a near-isogenic pair of race T (Tox1+) and race O (Tox1-) strains. This led to discovery of PKS2, a second PKS-encoding gene that maps at Tox1A and is required for both Ttoxin biosynthesis and high virulence to maize. Thus, the carbon chain of each T-toxin family member likely is assembled by action of two PKSs, which produce two polyketides, one of which may act as the starter unit for biosynthesis of the mature T-toxin molecule.

scholarly journals Molecular and Immunological Methods to Confirm Toxiginicity (Microcystin Production) of Westiellopsis Prolifica Isolated from Tigris River – Iraq

2019 ◽  
Vol 16 (4(Suppl.)) ◽  
pp. 0978
Author(s):  
Abed Et al.
Keyword(s):  
Laboratory Experiments ◽  
Immunological Methods ◽  
Laboratory Methods ◽  
Tigris River ◽  
Cyanobacterial Species ◽  
The World ◽  
Mcye Gene ◽  
Microcystin Production ◽  
Westiellopsis Prolifica ◽  
Significant Expression

Several toxigenic cyanobacteria produce the cyanotoxin (microcystin). Being a health and environmental hazard, screening of water sources for the presence of microcystin is increasingly becoming a recommended environmental procedure in many countries of the world. This study was conducted to assess the ability of freshwater cyanobacterial species Westiellopsis prolifica to produce microcystins in Iraqi freshwaters via using molecular and immunological tools. The toxigenicity of W. prolifica was compared via laboratory experiments with other dominant bloom-forming cyanobacteria isolated from the Tigris River: Microcystis aeruginosa, Chroococcus turigidus, Nostoc carneum, and Lyngbya sp. significant expression of mcyE gene and microcystin production was most evident in W. prolifica. Contrary to the prevailing concept that M. aeruginosa is a main microcystin producer in freshwaters around the world, no significant microcystin production was observed with this species throughout the time points studied in our laboratory methods. As for C. turigidus, N. carneum and Lyngbya sp., neither mcyE expression nor microcystin production was significant. Data from mcyE expression by RT-qPCR were generally in agreement with those obtained from microcystin quantification by ELISA. Interestingly, W. prolifica, which showed clear microcystin-producing ability in this study and which was not reported before in the literature to produce microcystin, can be added as a new microcystin producer to the list of toxigenic cyanobacteria.

Hunting the eagle killer: A cyanobacterial neurotoxin causes vacuolar myelinopathy

Science ◽  
2021 ◽  
Vol 371 (6536) ◽  
pp. eaax9050
Author(s):  
Steffen Breinlinger ◽  
Tabitha J. Phillips ◽  
Brigette N. Haram ◽  
Jan Mareš ◽  
José A. Martínez Yerena ◽  
...  
Keyword(s):  
United States ◽  
Aquatic Vegetation ◽  
Southeastern United States ◽  
Hydrilla Verticillata ◽  
Toxin Production ◽  
The United States ◽  
Biosynthetic Gene Cluster ◽  
Biosynthetic Gene ◽  
Bald Eagles ◽  
Cyanobacterial Species

Vacuolar myelinopathy is a fatal neurological disease that was initially discovered during a mysterious mass mortality of bald eagles in Arkansas in the United States. The cause of this wildlife disease has eluded scientists for decades while its occurrence has continued to spread throughout freshwater reservoirs in the southeastern United States. Recent studies have demonstrated that vacuolar myelinopathy is induced by consumption of the epiphytic cyanobacterial species Aetokthonos hydrillicola growing on aquatic vegetation, primarily the invasive Hydrilla verticillata. Here, we describe the identification, biosynthetic gene cluster, and biological activity of aetokthonotoxin, a pentabrominated biindole alkaloid that is produced by the cyanobacterium A. hydrillicola. We identify this cyanobacterial neurotoxin as the causal agent of vacuolar myelinopathy and discuss environmental factors—especially bromide availability—that promote toxin production.

scholarly journals Advancing Knowledge on Cyanobacterial Blooms in Freshwaters

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2583
Author(s):  
Elisabeth Vardaka ◽  
Konstantinos Ar. Kormas
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Mathematical Modelling ◽  
Ecological Status ◽  
Toxin Production ◽  
Cyanobacterial Blooms ◽  
Special Issue ◽  
Research Papers ◽  
Cyanobacterial Species ◽  
Water Quality Deterioration

Cyanobacterial blooms have become a frequent phenomenon in freshwaters worldwide; they are a widely known indicator of eutrophication and water quality deterioration. Information and knowledge contributing towards the evaluation of the ecological status of freshwaters, particularly since many are used for recreation, drinking water, and aquaculture, is valuable. This Special Issue, entitled “Advancing Knowledge on Cyanobacterial Blooms in Freshwaters”, includes 11 research papers that will focus on the use of complementary approaches, from the most recently developed molecular-based methods to more classical approaches and experimental and mathematical modelling regarding the factors (abiotic and/or biotic) that control the diversity of not only the key bloom-forming cyanobacterial species, but also their interactions with other biota, either in freshwater systems or their adjacent habitats, and their role in preventing and/or promoting cyanobacterial growth and toxin production.

scholarly journals Limited Microcystin, Anatoxin and Cylindrospermopsin Production by Cyanobacteria from Microbial Mats in Cold Deserts

Toxins ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 244 ◽  
Author(s):  
Nataliia Khomutovska ◽  
Małgorzata Sandzewicz ◽  
Łukasz Łach ◽  
Małgorzata Suska-Malawska ◽  
Monika Chmielewska ◽  
...  
Keyword(s):  
Microbial Mats ◽  
Sequence Similarity ◽  
Extreme Environment ◽  
Toxin Production ◽  
High Mountain ◽  
Rrna Gene ◽  
High Sequence Similarity ◽  
Small Water ◽  
Two Samples ◽  
Liquid Chromatography Tandem Mass

Toxic metabolites are produced by many cyanobacterial species. There are limited data on toxigenic benthic, mat-forming cyanobacteria, and information on toxic cyanobacteria from Central Asia is even more scarce. In the present study, we examined cyanobacterial diversity and community structure, the presence of genes involved in toxin production and the occurrence of cyanotoxins in cyanobacterial mats from small water bodies in a cold high-mountain desert of Eastern Pamir. Diversity was explored using amplicon-based sequencing targeting the V3-V4 region of the 16S rRNA gene, toxin potential using PCR-based methods (mcy, nda, ana, sxt), and toxins by enzyme-linked immunosorbent assays (ELISAs) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Molecular identification of cyanobacteria showed a high similarity of abundant taxa to Nostoc PCC-73102, Nostoc PCC-7524, Nodularia PCC-935 and Leptolyngbya CYN68. The PCRs revealed the presence of mcyE and/or ndaF genes in 11 samples and mcyD in six. The partial sequences of the mcyE gene showed high sequence similarity to Nostoc, Planktothrix and uncultured cyanobacteria. LC-MS/MS analysis identified six microcystin congeners in two samples and unknown peptides in one. These results suggest that, in this extreme environment, cyanobacteria do not commonly produce microcystins, anatoxins and cylindrospermopsins, despite the high diversity and widespread occurrence of potentially toxic taxa.

scholarly journals Intraspecific Variability in the Toxin Production and Toxin Profiles of In Vitro Cultures of Gambierdiscus polynesiensis (Dinophyceae) from French Polynesia

Toxins ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 735 ◽  
Author(s):  
Sébastien Longo ◽  
Manoella Sibat ◽  
Jérôme Viallon ◽  
Hélène Darius ◽  
Philipp Hess ◽  
...  
Keyword(s):  
Neuroblastoma Cell ◽  
Intraspecific Variability ◽  
Toxin Production ◽  
French Polynesia ◽  
Stationary Growth ◽  
Noticeable Increase ◽  
Intraspecific Variations ◽  
Geographic Origins ◽  
Liquid Chromatography Tandem Mass

Ciguatera poisoning (CP) is a foodborne disease caused by the consumption of seafood contaminated with ciguatoxins (CTXs) produced by dinoflagellates in the genera Gambierdiscus and Fukuyoa. The toxin production and toxin profiles were explored in four clones of G. polynesiensis originating from different islands in French Polynesia with contrasted CP risk: RIK7 (Mangareva, Gambier), NHA4 (Nuku Hiva, Marquesas), RAI-1 (Raivavae, Australes), and RG92 (Rangiroa, Tuamotu). Productions of CTXs, maitotoxins (MTXs), and gambierone group analogs were examined at exponential and stationary growth phases using the neuroblastoma cell-based assay and liquid chromatography–tandem mass spectrometry. While none of the strains was found to produce known MTX compounds, all strains showed high overall P-CTX production ranging from 1.1 ± 0.1 to 4.6 ± 0.7 pg cell−1. In total, nine P-CTX analogs were detected, depending on strain and growth phase. The production of gambierone, as well as 44-methylgamberione, was also confirmed in G. polynesiensis. This study highlighted: (i) intraspecific variations in toxin production and profiles between clones from distinct geographic origins and (ii) the noticeable increase in toxin production of both CTXs, in particular CTX4A/B, and gambierone group analogs from the exponential to the stationary phase.

scholarly journals Contrasting genetic variation and positive selection followed the divergence of NBS-encoding genes in Asian and European pears

BMC Genomics ◽  
2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Manyi Sun ◽  
Mingyue Zhang ◽  
Jugpreet Singh ◽  
Bobo Song ◽  
Zikai Tang ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Disease Resistance ◽  
Positive Selection ◽  
Gene Family ◽  
Selection Pressure ◽  
Black Spot ◽  
Orthologous Gene ◽  
European Pear ◽  
Encoding Gene ◽  
Encoding Genes

Abstract Background The NBS disease-related gene family coordinates the inherent immune system in plants in response to pathogen infections. Previous studies have identified NBS-encoding genes in Pyrus bretschneideri (‘Dangshansuli’, an Asian pear) and Pyrus communis (‘Bartlett’, a European pear) genomes, but the patterns of genetic variation and selection pressure on these genes during pear domestication have remained unsolved. Results In this study, 338 and 412 NBS-encoding genes were identified from Asian and European pear genomes. This difference between the two pear species was the result of proximal duplications. About 15.79% orthologous gene pairs had Ka/Ks ratio more than one, indicating two pear species undergo strong positive selection after the divergence of Asian and European pear. We identified 21 and 15 NBS-encoding genes under fire blight and black spot disease-related QTL, respectively, suggesting their importance in disease resistance. Domestication caused decreased nucleotide diversity across NBS genes in Asian cultivars (cultivated 6.23E-03; wild 6.47E-03), but opposite trend (cultivated 6.48E-03; wild 5.91E-03) appeared in European pears. Many NBS-encoding coding regions showed Ka/Ks ratio of greater than 1, indicating the role of positive selection in shaping diversity of NBS-encoding genes in pear. Furthermore, we detected 295 and 122 significantly different SNPs between wild and domesticated accessions in Asian and European pear populations. Two NBS genes (Pbr025269.1 and Pbr019876.1) with significantly different SNPs showed >5x upregulation between wild and cultivated pear accessions, and > 2x upregulation in Pyrus calleryana after inoculation with Alternaria alternata. We propose that positively selected and significantly different SNPs of an NBS-encoding gene (Pbr025269.1) regulate gene expression differences in the wild and cultivated groups, which may affect resistance in pear against A. alternata. Conclusion Proximal duplication mainly led to the different number of NBS-encoding genes in P. bretschneideri and P. communis genomes. The patterns of genetic diversity and positive selection pressure differed between Asian and European pear populations, most likely due to their independent domestication events. This analysis helps us understand the evolution, diversity, and selection pressure in the NBS-encoding gene family in Asian and European populations, and provides opportunities to study mechanisms of disease resistance in pear.

Cyanobacterial community and microcystin production in a recreational reservoir with constant Microcystis blooms

Hydrobiologia ◽  
2016 ◽  
Vol 779 (1) ◽  
pp. 105-125 ◽  
Author(s):  
Diego Bonaldo Genuário ◽  
Adriana Sturion Lorenzi ◽  
Livia Fernanda Agujaro ◽  
Ricardo de Lima Isaac ◽  
Maria Teresa de Paiva Azevedo ◽  
...  
Keyword(s):  
Cyanobacterial Community ◽  
Microcystis Blooms ◽  
Microcystin Production

scholarly journals Reevaluation of Production of Paralytic Shellfish Toxin by Bacteria Associated with Dinoflagellates of the Portuguese Coast

2003 ◽  
Vol 69 (9) ◽  
pp. 5693-5698 ◽  
Author(s):  
Claudia A. Martins ◽  
Paula Alvito ◽  
Maria João Tavares ◽  
Paulo Pereira ◽  
Gregory Doucette ◽  
...  
Keyword(s):  
Analytical Methods ◽  
Toxin Production ◽  
Bacterial Strains ◽  
Portuguese Coast ◽  
Shellfish Toxins ◽  
Paralytic Shellfish Toxins ◽  
Paralytic Shellfish ◽  
Cyanobacterial Species ◽  
Toxic Dinoflagellates ◽  
Shellfish Toxin

ABSTRACT Paralytic shellfish toxins (PSTs) are potent neurotoxins produced by certain dinoflagellate and cyanobacterial species. The autonomous production of PSTs by bacteria remains controversial. In this study, PST production by two bacterial strains, isolated previously from toxic dinoflagellates, was evaluated using biological and analytical methods. Analyses were performed under conditions determined previously to be optimal for toxin production and detection. Our data are inconsistent with autonomous bacterial PST production under these conditions, thereby challenging previous findings for the same strains.

scholarly journals Identification, Characterization, and Regulation of a Novel Antifungal Chitosanase Gene (cho) in Anabaena spp.

2010 ◽  
Vol 76 (9) ◽  
pp. 2769-2777 ◽  
Author(s):  
Vishal Gupta ◽  
Radha Prasanna ◽  
Chitra Natarajan ◽  
Ashish Kumar Srivastava ◽  
Jitender Sharma
Keyword(s):  
Pairwise Alignment ◽  
Site Directed Mutagenesis ◽  
Chitosan Oligosaccharide ◽  
Antifungal Effect ◽  
Antifungal Activities ◽  
Reverse Transcription Pcr ◽  
Putative Signal Peptide ◽  
Cyanobacterial Species ◽  
Encoding Gene ◽  
Hydrolysis Of

ABSTRACT Two contrasting cyanobacterial species (Anabaena fertilissima and Anabaena sphaerica) were selected based on differences in antifungal behavior in order to study the mechanism for production of an antifungal enzyme and the genes responsible for this production. In A. fertilissima, chitosanase and antifungal activities were increased significantly under of growth-limiting conditions (8 of light and 16 h of darkness). The lack of such activities in A. sphaerica was associated with high levels of protein that accumulated during the stationary phase (at 28 days) under the same light conditions. The gene putatively responsible for chitosanase and antifungal activities was amplified using specific primers, and sequence analysis of the amplified products (1.086 and 1.101 kb in A. sphaerica and A. fertilissima, respectively) showed that they belong to the glycoside hydrolase 3 (GH3)-like family of Anabaena variabilis ATCC 29413. Pairwise alignment of the corresponding protein sequences identified a putative signal peptide (amino acids 1 to 23) and some amino acid changes in the sequence of A. fertilissima which may be responsible for functioning of the chitosanase and the observed antifungal activity. Hydrolysis of the chitosan oligosaccharide (GlcN)5 to (GlcN)2 and (GlcN)3 confirmed the presence of chitosanase activity in A. fertilissima. Site-directed mutagenesis of the A. fertilissima chitosanase-encoding gene (cho) led to identification of catalytic residues (Glu-121 and Glu-141) important for the antifungal effect of the cho product. The level of expression of cho was monitored by quantitative real-time reverse transcription-PCR, which indicated that transcription of this gene is significantly enhanced under conditions that retard growth, such as a long dark period.

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