Oscillatoria has long been known to be polyphyletic. After recent resequencing of the reference strain for this genus, many Oscillatoria-like groups phylogenetically distant from the type species O. princeps remained unresolved. Here we describe one of these groups as a new genus Tenebriella. Most of the studied strains originate from Central Europe, where they are able to form prominent microbial mats. Despite the overall Oscillatoria-like morphology, Tenebriella can be distinguished by darker trichomes and forms a separate monophyletic clade in phylogenies inferred from the 16S rRNA gene and two additional loci (rpoC1, rbcLX). Within Tenebriella we recognize two new species differing from each other by morphological and ecological characteristics. First species does not fit any known taxon description, and thus is described as a new species T. amphibia. The latter one corresponds with the information available for Oscillatoria curviceps Agardh ex Gomont, and thus new combination T. curviceps is proposed. The phylogenetic analyses of the 16S-23S ITS region together with the comparison of the hypothetical secondary structures confirmed recognition of these two species and additionally revealed presence of a morphologically cryptic species Tenebriella sp. The results corroborate frequent recurrence of convergent morphotypes in the evolution of cyanobacteria and justify further exploration even of the intensively studied European freshwaters using molecular phylogenetics to discover new and ecologically relevant taxa.

• Klíčová slova
• Cyanobacteria, ITS, Multilocus analysis, Phylogeny, Polyphyly,
• MeSH
• DNA bakterií genetika   MeSH
• fylogeneze MeSH
• Oscillatoria * genetika   MeSH
• RNA ribozomální 16S genetika   MeSH
• sekvenční analýza DNA MeSH
• sinice * genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA bakterií MeSH
• RNA ribozomální 16S MeSH

Anatoxin-a, homoanatoxin-a, and dihydroanatoxin-a are potent cyanobacterial neurotoxins. They are biosynthesized in cyanobacteria from proline and acetate by a pathway involving three polyketide synthases. We report the identification of carboxy-anatoxin-a, carboxy-homoanatoxin-a, and carboxy-dihydroanatoxin-a in acidic extracts of Cuspidothrix issatschenkoi CHARLIE-1, Oscillatoria sp. PCC 6506, and Cylindrospermum stagnale PCC 7417, respectively, using liquid chromatography coupled to mass spectrometry. The structure of these carboxy derivatives was confirmed by mass spectrometry and by isotopic incorporation experiments using labeled proline and acetate. Each of these three cyanobacteria only produce one carboxy-anatoxin, suggesting that these metabolites are the product of the hydrolysis by AnaA, the type II thioesterase, of the thioesters bound to AnaG, the last polyketide synthase of the pathway. By measuring the rate of isotopic incorporation of labeled proline into carboxy-homoanatoxin-a and homoanatoxin-a produced by Oscillatoria sp. PCC 6506, we show that carboxy-homoanatoxin-a is the intracellular precursor of homoanatoxin-a, and that homoanatoxin-a is then excreted into the extracellular medium. The transformation of carboxy-homoanatoxin-a into homoanatoxin-a is a very slow two-step process, with accumulation of carboxy-homoanatoxin-a, suggesting that the decarboxylation is spontaneous and not enzymatically catalyzed. However, an unidentified and extracellular catalyst accelerates the decarboxylation when the cell extracts are prepared at neutral pH.

• MeSH
• bakteriální toxiny chemie   metabolismus   MeSH
• bicyklické sloučeniny heterocyklické chemie   metabolismus   MeSH
• chromatografie kapalinová MeSH
• molekulární struktura MeSH
• Oscillatoria chemie   MeSH
• polyketidsynthasy chemie   metabolismus   MeSH
• prolin chemie   MeSH
• sinice chemie   metabolismus   MeSH
• toxiny kmene Cyanobacteria MeSH
• tropany chemie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• anatoxin a MeSH Prohlížeč
• bakteriální toxiny MeSH
• bicyklické sloučeniny heterocyklické MeSH
• homoanatoxin-a MeSH Prohlížeč
• polyketidsynthasy MeSH
• prolin MeSH
• toxiny kmene Cyanobacteria MeSH
• tropany MeSH

The aim of the work was to synthesize a molecularly imprinted material for the selective solid-phase extraction (SPE) of β-N-methylamino-L-alanine (L-2-amino-3-methylpropionic acid; BMAA) from cyanobacterial extracts. BMAA and its structural analogs that can be used as template are small, polar and hydrophilic molecules. These molecules are poorly soluble in organic solvents that are commonly used for the synthesis of acrylic-based polymers. Therefore, a sol gel approach was chosen to carry out the synthesis and the resulting sorbents were evaluated with different extraction procedures in order to determine their ability to selectively retain BMAA. The presence of imprinted cavities in the sorbent was demonstrated by comparing elution profiles obtained by using molecularly imprinted silica (MIS) and non-imprinted silica (NIS) as a control. The molecularly imprinted solid-phase extraction (MISPE) procedure was first developed in a pure medium (acetonitrile) and further optimized for the treatment of cyanobacterial samples. It was characterized by high elution recoveries (89% and 77% respectively in pure and in real media).The repeatability of the extraction procedure in pure medium, in real medium and the reproducibility of MIS synthesis all expressed as RSD values of extraction recovery of BMAA were equal to 3%, 12% and 5%, respectively. A MIS capacity of 0.34 µmol/g was measured. The matrix effects, which affected the quantification of BMAA when employing a mixed mode sorbent, were completely removed by adding a clean-up step of the mixed-mode sorbent extract on the MIS.

• Klíčová slova
• Molecularly imprinted silica, Solid phase extraction, Sol–gel, β-N-methylamino-l-alanine,
• MeSH
• adsorpce MeSH
• aminokyseliny diaminové analýza   chemie   MeSH
• extrakce na pevné fázi MeSH
• molekulový imprinting MeSH
• Oscillatoria chemie   MeSH
• oxid křemičitý chemie   MeSH
• toxiny kmene Cyanobacteria MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aminokyseliny diaminové MeSH
• beta-N-methylamino-L-alanine MeSH Prohlížeč
• oxid křemičitý MeSH
• toxiny kmene Cyanobacteria MeSH