Journal articles: 'Tychonema'

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Evseev, Peter, Irina Tikhonova, Andrei Krasnopeev, Ekaterina Sorokovikova, Anna Gladkikh, Oleg Timoshkin, Konstantin Miroshnikov, and Olga Belykh. "Tychonema sp. BBK16 Characterisation: Lifestyle, Phylogeny and Related Phages." Viruses 15, no. 2 (February 5, 2023): 442. http://dx.doi.org/10.3390/v15020442.

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Cyanobacterial expansion is harmful to the environment, the ecology of Lake Baikal and the economy of nearby regions and can be dangerous to people and animals. Since 2011, the process of colonisation of the lake with potentially toxic cyanobacteria belonging to the genus Tychonema has continued. An understanding of the mechanism of successful expansion of Tychonema requires scrutiny of biological and genomic features. Tychonema sp. BBK16 was isolated from the coastal zone of Lake Baikal. The morphology of BBK16 biofilm was studied with light, scanning electron and confocal microscopy. The biofilm is based on filaments of cyanobacteria, which are intertwined like felt; there are also dense fascicles of rope-like twisted filaments that impart heterogeneity to the surface of the biofilm. Genome sequencing, intergenomic comparisons and phylogenetic analyses indicated that Tychonema sp. BBK16 represent a new species related to planktic cyanobacterium Tychonema bourrellyi, isolated from Alpine lentic freshwater. Genome investigation revealed the genes possibly responsible for the mixotrophic lifestyle. The presence of CRISPR-Cas and restriction modification defence mechanisms allowed to suggest the existence of phages infecting Tychonema sp. BBK16. Analysis of CRISPR spacers and prophage-derived regions allowed to suggest related cyanophages. Genomic analysis supported the assumption that mobile elements and horizontal transfer participate in shaping the Tychonema sp. BBK16 genome. The findings of the current research suggest that the aptitude of Tychonema sp. BBK16 for biofilm formation and, possibly, its mixotrophic lifestyle provide adaptation advantages that lead to the successful expansion of this cyanobacterium in the Baikal’s conditions of freshwater lake environments.

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Bauer, Franziska, Michael Stix, Bernadett Bartha-Dima, Juergen Geist, and Uta Raeder. "Spatio-Temporal Monitoring of Benthic Anatoxin-a-Producing Tychonema sp. in the River Lech, Germany." Toxins 14, no. 5 (May 20, 2022): 357. http://dx.doi.org/10.3390/toxins14050357.

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Incidents with toxic benthic cyanobacteria blooms have been increasing recently. In 2019, several dogs were poisoned in the river Lech (Germany) by the benthic anatoxin-a-producing genus Tychonema. To characterize spatial and temporal distribution of potentially toxic Tychonema in this river, a systematic monitoring was carried out in 2020, focusing on the occurrence of the genus, its toxin production and habitat requirements. Tychonema and cyanobacterial community composition in benthic mats and pelagic samples were identified using a combined approach of microscopy and DNA sequencing of the 16S rRNA gene. In addition, anatoxin-a concentrations of selected samples were measured using the ELISA method. The habitat was characterized to assess the ecological requirements and growth conditions of Tychonema. Tychonema mats and anatoxin-a were detected at several sampling sites throughout the entire study period. Toxin concentrations increased with the progression of the vegetation period and with flow direction, reaching values between 0 and 220.5 µg/L. Community composition differed among pelagic and benthic samples, with life zone and substrate condition being the most important factors. The results of this study highlight the importance of monitoring and understanding the factors determining occurrence and toxin production of both pelagic and benthic cyanobacteria due to their relevance for the health of humans and aquatic ecosystems.

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Schwarzenberger, Anke, and Dominik Martin-Creuzburg. "Daphnia’s Adaptive Molecular Responses to the Cyanobacterial Neurotoxin Anatoxin-α Are Maternally Transferred." Toxins 13, no. 5 (April 30, 2021): 326. http://dx.doi.org/10.3390/toxins13050326.

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Cyanobacterial blooms are an omnipresent and well-known result of eutrophication and climate change in aquatic systems. Cyanobacteria produce a plethora of toxic secondary metabolites that affect humans, animals and ecosystems. Many cyanotoxins primarily affect the grazers of phytoplankton, e.g., Daphnia. The neurotoxin anatoxin-α has been reported world-wide; despite its potency, anatoxin-α and its effects on Daphnia have not been thoroughly investigated. Here, we investigated the effects of the anatoxin-α-producing Tychonema on life-history parameters and gene expression of nicotine-acetylcholine receptors (NAR), the direct targets of anatoxin-α, using several D. magna clones. We used juvenile somatic growth rates as a measure of fitness and analyzed gene expression by qPCR. Exposure to 100% Tychonema reduced the clones’ growth rates and caused an up-regulation of NAR gene expression. When 50% of the food consisted of Tychonema, none of the clones were reduced in growth and only one of them showed an increase in NAR gene expression. We demonstrate that this increased NAR gene expression can be maternally transferred and that offspring from experienced mothers show a higher growth rate when treated with 50% Tychonema compared with control offspring. However, the addition of further (anthropogenic) stressors might impair Daphnia’s adaptive responses to anatoxin-α. Especially the presence of certain pollutants (i.e., neonicotinoids), which also target NARs, might reduce Daphnia’s capability to cope with anatoxin-α.

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Fastner, Jutta, Camilla Beulker, Britta Geiser, Anja Hoffmann, Roswitha Kröger, Kinga Teske, Judith Hoppe, et al. "Fatal Neurotoxicosis in Dogs Associated with Tychoplanktic, Anatoxin-a Producing Tychonema sp. in Mesotrophic Lake Tegel, Berlin." Toxins 10, no. 2 (January 31, 2018): 60. http://dx.doi.org/10.3390/toxins10020060.

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In May 2017, at least 12 dogs showed signs of acute neurotoxicosis after swimming in or drinking from Lake Tegel, a mesotrophic lake in Berlin, Germany, and several of the affected dogs died shortly afterwards despite intensive veterinary treatment. Cyanobacterial blooms were not visible at the water surface or the shorelines. However, detached and floating water moss (Fontinalis antipyretica) with high amounts of Tychonema sp., a potential anatoxin-a (ATX) producing cyanobacterium, was found near the beaches where the dogs had been swimming and playing. Necropsies of two of the dogs revealed no specific lesions beside the anamnestic neurotoxicosis. ATX was detected in concentrations up to 8700 µg L−1 in the stomach contents, while other (neuro)toxic substances were not found. In the aqueous fraction of Fontinalis/Tychonema clumps sampled after the casualties, ATX was found in concentrations up to 1870 µg L−1. This is the first report of a dense population of Tychonema sp. in stands of Fontinalis resulting in high ATX contents. This case emphasizes the need for further investigation of potentially toxic, non-bloom forming cyanobacteria in less eutrophic water bodies and underlines the novel challenge of developing appropriate surveillance schemes for respective bathing sites.

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Morone, Janaína, Graciliana Lopes, Marco Preto, Vítor Vasconcelos, and Rosário Martins. "Exploitation of Filamentous and Picoplanktonic Cyanobacteria for Cosmetic Applications: Potential to Improve Skin Structure and Preserve Dermal Matrix Components." Marine Drugs 18, no. 9 (September 22, 2020): 486. http://dx.doi.org/10.3390/md18090486.

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The use of natural products in skin care formulations gained interest as a concern for modern societies. The undesirable side effects of synthetic compounds, as well as the associated environmental hazards, have driven investigation on photosynthetic organisms as sustainable sources of effective and environmentally friendly ingredients. The use of natural extracts in cosmetics has been highlighted and, along with plants and algae, cyanobacteria have come into focus. Due to their low culture demands, high grow rates and ability to produce a wide variability of bioactive metabolites, cyanobacteria emerged as an economic and sustainable base for the cosmetic industry. In this study, we evaluated the potential of ethanol extracts of picocyanobacteria strains of the genera Cyanobium and Synechocystis and filamentous strains of the genera Nodosilinea, Phormidium and Tychonema for skin applications, with focus in the field of anti-aging. The extracts were analyzed for their pigment profile, phenolic content, antioxidant potential, cytotoxicity against keratinocytes (HaCat), fibroblasts (3T3L1), endothelial cells (hCMEC/D3) and capacity to inhibit hyaluronidase (HAase). The total carotenoid content ranged from 118.69 to 383.89 μg g−1 of dry biomass, and the total phenolic content from 1.07 to 2.45 mg GAE g−1. Identified carotenoids consisted of zeaxanthin, lutein, canthaxanthin, echinenone and β-carotene, with zeaxanthin and lutein being the most representative (49.82 and 79.08 μg g−1, respectively). The highest antioxidant potential was found for Phormidium sp. LEGE 05292 and Tychonema sp. LEGE 07196 for superoxide anion radical (O2•−) scavenging (IC50 of 822.70 and 924 μg mL−1, respectively). Low or no cytotoxicity were registered. Regarding HAase inhibition, Tychonema sp. LEGE 07196 and Cyanobium sp. LEGE 07175 showed the best IC50 (182.74 and 208.36 μg mL−1, respectively). In addition, an increase in fibroblast proliferation was registered with these same strains. From this work, the ethanol extracts of the species Tychonema sp. and Cyanobium sp. are particularly interesting for their potential application in anti-aging formulations, once they stimulated fibroblast proliferation and inhibit hyaluronic acid digestion.

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6

Komárek, Jiří, and Patrizia Albertano. "Cell structure of a planktic cyanoprokaryote, Tychonema bourrellyi." Algological Studies/Archiv für Hydrobiologie, Supplement Volumes 75 (October 27, 1995): 157–66. http://dx.doi.org/10.1127/algol_stud/75/1995/157.

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7

Shams, S., C. Capelli, L. Cerasino, A. Ballot, D. R. Dietrich, K. Sivonen, and N. Salmaso. "Anatoxin-a producing Tychonema (Cyanobacteria) in European waterbodies." Water Research 69 (February 2015): 68–79. http://dx.doi.org/10.1016/j.watres.2014.11.006.

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8

Shiels, Browne, Donovan, Murray, and Saha. "Molecular Characterization of Twenty-Five Marine Cyanobacteria Isolated from Coastal Regions of Ireland." Biology 8, no. 3 (August 7, 2019): 59. http://dx.doi.org/10.3390/biology8030059.

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Twenty-five marine cyanobacteria isolated from Irish coasts were characterized based on their morphological characters and 16S rRNA gene sequence analysis. In addition, superoxide dismutase (SOD) and malate dehydrogenase (MDH) isoenzyme banding patterns were used to differentiate two morphologically ambiguous isolates. In this study, six new cyanobacteria-specific primers were designed, and a 16S rRNA gene of twenty-five morphologically diverse cyanobacteria was successfully PCR amplified (1198–1396 bps). Assembled 16S rRNA sequences were used both for a basic local alignment search tool (BLAST) analysis for genus-level identification and to generate a phylogenetic tree, which yielded two major clusters: One with morphologically homogenous cyanobacteria and the other with morphologically very diverse cyanobacteria. Kamptonema okenii and Tychonema decoloratum were isolated from a single field sample of Ballybunion and were originally identified as the same ‘Oscillatoria sp.’ based on preliminary morphological observations. However, an alignment of 16S rRNA gene sequences and SOD and MDH isoenzyme banding pattern analyses helped in differentiating the morphologically-indistinguishable ‘Oscillatoria sp.’. Finally, after a re-evaluation of their morphological characters using modern taxonomic publications, the originally identified ‘Oscillatoria sp.’ were re-identified as Kamptonema okenii and Tychonema decoloratum, thus supporting the polyphasic approach of cyanobacteria characterization.

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9

Bauer, Franziska, Jutta Fastner, Bernadett Bartha-Dima, Wolfram Breuer, Almuth Falkenau, Christian Mayer, and Uta Raeder. "Mass Occurrence of Anatoxin-a- and Dihydroanatoxin-a-Producing Tychonema sp. in Mesotrophic Reservoir Mandichosee (River Lech, Germany) as a Cause of Neurotoxicosis in Dogs." Toxins 12, no. 11 (November 20, 2020): 726. http://dx.doi.org/10.3390/toxins12110726.

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In August 2019, three dogs died after bathing in or drinking from Mandichosee, a mesotrophic reservoir of the River Lech (Germany). The dogs showed symptoms of neurotoxic poisoning and intoxication with cyanotoxins was considered. Surface blooms were not visible at the time of the incidents. Benthic Tychonema sp., a potential anatoxin-a (ATX)-producing cyanobacterium, was detected in mats growing on the banks, as biofilm on macrophytes and later as aggregations floating on the lake surface. The dogs’ pathological examinations showed lung and liver lesions. ATX and dihydroanatoxin-a (dhATX) were detected by LC-MS/MS in the stomachs of two dogs and reached concentrations of 563 and 1207 µg/L, respectively. Anatoxins (sum of ATX and dhATX, ATXs) concentrations in field samples from Mandichosee ranged from 0.1 µg/L in the open water to 68,000 µg/L in samples containing a large amount of mat material. Other (neuro)toxic substances were not found. A molecular approach was used to detect toxin genes by PCR and to reveal the cyanobacterial community composition by sequencing. Upstream of Mandichosee, random samples were taken from other Lech reservoirs, uncovering Tychonema and ATXs at several sampling sites. Similar recent findings emphasize the importance of focusing on the investigation of benthic toxic cyanobacteria and applying appropriate monitoring strategies in the future.

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10

Rudi, Knut, Olav M. Skulberg, and Kjetill S. Jakobsen. "Evolution of Cyanobacteria by Exchange of Genetic Material among Phyletically Related Strains." Journal of Bacteriology 180, no. 13 (July 1, 1998): 3453–61. http://dx.doi.org/10.1128/jb.180.13.3453-3461.1998.

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ABSTRACT The cyanobacterial radiation consists of several lineages of phyletically (morphologically and genetically) related organisms. Several of these organisms show a striking resemblance to fossil counterparts. To investigate the molecular mechanisms responsible for stabilizing or homogenizing cyanobacterial characters, we compared the evolutionary rates and phylogenetic origins of the small-subunit rRNA-encoding DNA (16S rDNA), the conserved gene rbcL(encoding d-ribulose 1,5-bisphosphate carboxylase-oxygenase large subunit), and the less conserved gene rbcX. This survey includes four categories of phyletically related organisms: 16 strains of Microcystis, 6 strains of Tychonema, 10 strains of Planktothrix, and 12 strains ofNostoc. Both rbcL and rbcX can be regarded as neutrally evolving genes, with 95 to 100% and 50 to 80% synonymous nucleotide substitutions, respectively. There is generally low sequence divergence within the Microcystis,Tychonema, and Planktothrix categories both forrbcLX and 16S rDNA. The Nostoc category, on the other hand, consists of three genetically clustered lineages for these loci. The 16S rDNA and rbcLX phylogenies are not congruent for strains within the clustered groups. Furthermore, analysis of the phyletic structure for rbcLX indicates recombinational events between the informative sites within this locus. Thus, our results are best explained by a model involving both intergenic and intragenic recombinations. This evolutionary model explains the DNA sequence clustering for the modern species as a result of sequence homogenization (concerted evolution) caused by exchange of genetic material for neutrally evolving genes. The morphological clustering, on the other hand, is explained by structural and functional stability of these characters. We also suggest that exchange of genetic material for neutrally evolving genes may explain the apparent stability of cyanobacterial morphological characters, perhaps over billions of years.

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WEI, Zhi-Hong, Meng-Ling ZHU, Gong-Liang YU, and Ren-Hui LI. "OCCURRENCE OF PLANKTONIC CYANOBACTERIUM TYCHONEMA BOUURRELLYI IN ERHAI LAKE AND ITS TAXONOMIC STUDIES." Acta Hydrobiologica Sinica 36, no. 6 (July 19, 2013): 1171–75. http://dx.doi.org/10.3724/sp.j.1035.2012.01171.

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12

Shao, Jihai, Liang Peng, Si Luo, Gongliang Yu, Ji-dong Gu, Shen Lin, and Renhui Li. "First report on the allelopathic effect of Tychonema bourrellyi (Cyanobacteria) against Microcystis aeruginosa (Cyanobacteria)." Journal of Applied Phycology 25, no. 5 (January 6, 2013): 1567–73. http://dx.doi.org/10.1007/s10811-012-9969-z.

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13

Zhang, Hang, Gaofei Song, Jihai Shao, Xianfen Xiang, Qi Li, Youxin Chen, Ping Yang, and Gongliang Yu. "Dynamics and polyphasic characterization of odor-producing cyanobacterium Tychonema bourrellyi from Lake Erhai, China." Environmental Science and Pollution Research 23, no. 6 (November 13, 2015): 5420–30. http://dx.doi.org/10.1007/s11356-015-5749-z.

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TIKHONOVA, I. V., A. V. KUZMIN, E. G. SOROKOVIKOVA, A. YU KRASNOPEEV, G. A. FEDOROVA, N. A. ZHUCHENKO, E. V. YELETSKAYA, et al. "Microcystin-Producing Cyanobacteria <i>Tychonema</i> sp. from Biofilms of Lake Baikal." Chemistry for Sustainable Development 30, no. 4 (2022): 415–23. http://dx.doi.org/10.15372/csd2022399.

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TIKHONOVA, I. V., A. V. KUZMIN, E. G. SOROKOVIKOVA, A. YU KRASNOPEEV, G. A. FEDOROVA, N. A. ZHUCHENKO, E. V. YELETSKAYA, et al. "Microcystin-Producing Cyanobacteria <i>Tychonema </i>sp. from Biofilms of Lake Baikal." Химия в интересах устойчивого развития 30, no. 4 (2022): 427–35. http://dx.doi.org/10.15372/khur2022399.

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Capelli, Camilla, Leonardo Cerasino, Adriano Boscaini, and Nico Salmaso. "Molecular tools for the quantitative evaluation of potentially toxigenic Tychonema bourrellyi (Cyanobacteria, Oscillatoriales) in large lakes." Hydrobiologia 824, no. 1 (January 24, 2018): 109–19. http://dx.doi.org/10.1007/s10750-018-3513-3.

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Geng, Ruozhen, Wenke Li, Aimin Chao, Xiaoyu Guo, Hua Li, Gongliang Yu, and Renhui Li. "Establishment of a New Filamentous Cyanobacterial Genus, Microcoleusiopsis gen. nov. (Microcoleaceae, Cyanobacteria), from Benthic Mats in Open Channel, Jiangxi Province, China." Diversity 13, no. 11 (October 29, 2021): 548. http://dx.doi.org/10.3390/d13110548.

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Cyanobacterial taxonomic studies performed by using the modern approaches always lead to creation of many new genera and species. During the field survey for cyanobacterial resources in China, a filamentous cyanobacterial strain was successfully isolated from a microbial mat attached to rock surfaces of the Ganfu Channel, Jiangxi Province, China. This strain was morphologically similar to the cyanobacterial taxa belonging to the genera Microcoleus and Phormidium. The phylogenetic analyses based on 16S rRNA gene sequences showed that this strain formed a well-supported clade, close to the filamentous genera Microcoleus, Tychonema, and Kamptonema. The maximum similarity of 16S rRNA gene sequence of this strain with the related genera was 95.04%, less than the threshold for distinguishing bacterial genus. The ITS secondary structures also distinguish this strain from the related cyanobacterial genera. Therefore, combined with morphology, 16S rRNA gene sequence, and ITS secondary structures, a novel cyanobacterial genus here as Microcoleusiopsis was established, with the species type as Microcoleusiopsis ganfuensis.

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Hirose, Yuu, Takuhei Shiozaki, Masahiro Otani, Sakae Kudoh, Satoshi Imura, Toshihiko Eki, and Naomi Harada. "Investigating Algal Communities in Lacustrine and Hydro-Terrestrial Environments of East Antarctica Using Deep Amplicon Sequencing." Microorganisms 8, no. 4 (March 31, 2020): 497. http://dx.doi.org/10.3390/microorganisms8040497.

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Antarctica has one of the most extreme environments on Earth, with low temperatures and low nutrient levels. Antarctica’s organisms live primarily in the coastal, ice-free areas which cover approximately 0.18% of the continent’s surface. Members of Cyanobacteria and eukaryotic algae are important primary producers in Antarctica since they can synthesize organic compounds from carbon dioxide and water using solar energy. However, community structures of photosynthetic algae in Antarctica have not yet been fully explored at molecular level. In this study, we collected diverse algal samples in lacustrine and hydro-terrestrial environments of Langhovde and Skarvsnes, which are two ice-free regions in East Antarctica. We performed deep amplicon sequencing of both 16S ribosomal ribonucleic acid (rRNA) and 18S rRNA genes, and we explored the distribution of sequence variants (SVs) of these genes at single nucleotide difference resolution. SVs of filamentous Cyanobacteria genera, including Leptolyngbya, Pseudanabaena, Phormidium, Nodosilinea, Geitlerinama, and Tychonema, were identified in most of the samples, whereas Phormidesmis SVs were distributed in fewer samples. We also detected unicellular, multicellular or heterocyst forming Cyanobacteria strains, but in relatively small abundance. For SVs of eukaryotic algae, Chlorophyta, Cryptophyta, and Ochrophyta were widely distributed among the collected samples. In addition, there was a red colored bloom of eukaryotic alga, Geminigera cryophile (Cryptophyta), in the Langhovde coastal area. Eukaryotic SVs of Acutuncus antarcticus and/or Diphascon pingue of Tardigrada were dominant among most of the samples. Our data revealed the detailed structures of the algal communities in Langhovde and Skarvsnes. This will contribute to our understanding of Antarctic ecosystems and support further research into this subject.

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Granada, Miguel Á. "Johannes Kepler. The Sun as the Heart of the World." Journal for the History of Astronomy 53, no. 2 (May 2022): 133–40. http://dx.doi.org/10.1177/00218286221082044.

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In two early unpublished texts (a Disputation in favor of Copernicus of 1593 and the Apologia pro Tychone against Ursus of 1600), Kepler argued with the Pythagoreans that, contrary to Aristotle ( De caelo, ii, 13), the geometrical center of the cosmos coincides with its natural center. Since the Sun is the body that occupies this central position, Kepler conceives it as the heart of the world and the principle of planetary motion. In the following study, we examine how Kepler further develops this pivotal theme in a letter to Herwart von Hohenburg of 25 March 1605 and later in the Dissertatio cum nuncio sidereo (Prague, 1610) as well as in a German translation and critical commentary of the Aristotelian chapter, which ultimately remained unpublished as well.

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Mehner, C., S. Kehraus, A. Krick, D. Müller, and GM König. "New cyclic peptides from the cyanobacterium Tychonema sp." Planta Medica 72, no. 11 (August 24, 2006). http://dx.doi.org/10.1055/s-2006-949939.

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Pinto, Federica, Adrian Tett, Federica Armanini, Francesco Asnicar, Adriano Boscaini, Edoardo Pasolli, Moreno Zolfo, Claudio Donati, Nico Salmaso, and Nicola Segata. "Draft Genome Sequence of the Planktic Cyanobacterium Tychonema bourrellyi, Isolated from Alpine Lentic Freshwater." Genome Announcements 5, no. 47 (November 22, 2017). http://dx.doi.org/10.1128/genomea.01294-17.

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ABSTRACT We describe here the draft genome sequence of the cyanobacterium Tychonema bourrellyi, assembled from a metagenome of a nonaxenic culture. The strain (FEM_GT703) was isolated from a freshwater sample taken from Lake Garda, Italy. The draft genome sequence represents the first assembled T. bourrellyi strain.

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Greco, Carla, Dale T. Andersen, Ian Hawes, Alexander M. C. Bowles, Marian L. Yallop, Gary Barker, and Anne D. Jungblut. "Microbial Diversity of Pinnacle and Conical Microbial Mats in the Perennially Ice-Covered Lake Untersee, East Antarctica." Frontiers in Microbiology 11 (December 10, 2020). http://dx.doi.org/10.3389/fmicb.2020.607251.

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Antarctic perennially ice-covered lakes provide a stable low-disturbance environment where complex microbially mediated structures can grow. Lake Untersee, an ultra-oligotrophic lake in East Antarctica, has the lake floor covered in benthic microbial mat communities, where laminated organo-sedimentary structures form with three distinct, sympatric morphologies: small, elongated cuspate pinnacles, large complex cones and flat mats. We examined the diversity of prokaryotes and eukaryotes in pinnacles, cones and flat microbial mats using high-throughput sequencing of 16S and 18S rRNA genes and assessed how microbial composition may underpin the formation of these distinct macroscopic mat morphologies under the same environmental conditions. Our analysis identified distinct clustering of microbial communities according to mat morphology. The prokaryotic communities were dominated by Cyanobacteria, Proteobacteria, Verrucomicrobia, Planctomycetes, and Actinobacteria. While filamentous Tychonema cyanobacteria were common in all mat types, Leptolyngbya showed an increased relative abundance in the pinnacle structures only. Our study provides the first report of the eukaryotic community structure of Lake Untersee benthic mats, which was dominated by Ciliophora, Chlorophyta, Fungi, Cercozoa, and Discicristata. The eukaryote richness was lower than for prokaryote assemblages and no distinct clustering was observed between mat morphologies. These findings suggest that cyanobacterial assemblages and potentially other bacteria and eukaryotes may influence structure morphogenesis, allowing distinct structures to form across a small spatial scale.

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Cerasino, Leonardo, Camilla Capelli, and Nico Salmaso. "A comparative study of the metabolic profiles of common nuisance cyanobacteria in southern perialpine lakes." Advances in Oceanography and Limnology 8, no. 1 (May 31, 2017). http://dx.doi.org/10.4081/aiol.2017.6381.

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This work allowed the comparison of the metabolic profiles of the most important cyanobacteria species in southern perialpine lakes, namely Aphanizomenon flos-aquae, Dolichospermum lemmermannii, Microcystis aeruginosa, Planktothrix rubescens, and Tychonema bourrellyi. Monospecific cultures were obtained from samples of 3 different natural lakes (Garda, Idro, and Caldonazzo). LC-MS/MS analyses were conducted on strains. A first set of experiments was aimed at assessing the presence of the best known toxins (microcystins, nodularins, (homo)anatoxin-a, cylindrospermopsins, paralytic shellfish poisons) in the cultures. Results of this screening study revealed that M. aeruginosa and P. rubescens produced toxic peptides (microcystins), T. bourrellyi produced toxic alkaloids (anatoxin-a and possibly some paralytic shellfish toxins), Aph. flos-aquae and D. lemmermannii did not produce any of the analyzed toxins. M. aeruginosa and P. rubescens showed typical microcystin production with LR form dominant in the former, and RRdm form dominant in the latter. A second set of experiments was aimed at comparing the capability of the 5 cyanobacterial species to produce peptidic secondary metabolites. For this purpose, an untargeted peptidomic analysis was conducted on the strains. The analysis allowed revealing globally 328 metabolites, spanning in a mass range between 400 and 2000 Da. The majority of compounds with masses in the 500-1200 Da range (corresponding to the majority of peptidic secondary metabolites) resulted to be produced by M. aeruginosa and P. rubescens strains, thus indicating a higher ability of these species to produce non-ribosomal peptides compared to the others. 27 metabolites out of 328 could be putatively assigned to specific classes of compounds: microcystins, aeruginosins and anabaenopeptins were the most represented classes of compounds, and were mostly found in M. aeruginosa and P. rubescens strains.

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Cerasino, Leonardo, and Nico Salmaso. "Co-occurrence of anatoxin-a and microcystins in Lake Garda and other deep subalpine lakes." Advances in Oceanography and Limnology 11, no. 1 (May 12, 2020). http://dx.doi.org/10.4081/aiol.2020.8677.

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Cyanotoxins are a global concern in freshwaters and eutrophication and climate changes can have synergistic effects in exacerbating the problem. Deep Subalpine Lakes (DSL) are a group of lakes of huge economic and naturalistic importance in Italy. Together with eutrophication (occurred during 1960s and 1970s) and re-oligotrophication (from 1990 onward) these lake have been experiencing warming and increase of the water column stability. These changes have influenced the phytoplankton (comprised the cyanobacteria) community of the lakes. Four DSL lakes (Lakes Garda, Iseo, Como and Lugano) have been studied with the aim of comparing their toxic potential. For one of them (Lake Garda) an 8 years survey was conducted, allowing a long term trend analysis. Toxin analysis was conducted on a monthly basis by targeted LC-MS/MS. A screening for anatoxins, cylindrospermopsins, saxitoxins, microcystins (MCs) and nodularins was carried out. Among all the listed toxins, only one anatoxin and five MCs were detected in the lakes. In particular, the alkaloid Anatoxin-a (ATX) was found dominant Lakes Garda, Iseo and Como and absent in lake Lugano; the MC-[D-Asp3]RR was found as the most abundant MC in all four lakes. Four other minoritary MCs were also found. The two major toxins are produced by two different cyanobacteria (Tychonema bourrellyi and Planktothrix rubescens) which have however similar ecological traits. Peaks of these toxins occur in warmer months (typically between May and September) in the thermocline layer (around 20 m, in the considered lakes). In summer 2016, the highest concentrations of ATX and total microcystins (MCs) were registered in Lake Iseo (1100 and 430ngL-1, respectively), while in the other lakes values were approximately twice lower. In the lakes where it is present, ATX peak levels are much higher than MCs, thus highlighting the necessity of considering ATX in the procedures of risk assessment. The importance of ATX is expected to further grow in the future with respect to MCs, as demonstrated by the long term trend analysis carried out in Lake Garda that showed a clear decline for MCs from 2009 till 2016 and a relative constancy for ATX.

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Journal articles on the topic 'Tychonema'

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