Filamentous cyanoprokaryotes (Cyanoprokaryota/Cyanobacteria) in standing waters of Bulgaria: diversity and ecology

Cyanoprokaryotes are widespread organisms, which dominate in different water basins. In the present study, we have investigated the diversity of this group and related physicochemical parameters in 35 standing water basins in Bulgaria. We found 29 cyanoprokaryotic species, which belong to 13 genera from the orders Synechococcales, Spirulinales and Oscillatoriales. The frequency quotient of each species was calculated. Information about the distribution of the identified species and typology of the water basins is also provided

MOLECULAR AND PHYLOGENETIC CHARACTERIZATION OF PHORMIDIUM SPECIES (CYANOPROKARYOTA)

The accurate determination of species of Cyanoprokaryota/Cyanophyceae has many important applications. These include the assessment of risk with regard to blooms in water reservoirs as well as the identification of species capable of producing valuable bioactive compounds. Commonly, Cyanoprokaryota are classified based on their morphology. However, morphological criteria are not always reliable because they may change, for example, due to environmental factors. Thus, genetic and molecular analyses are a promising additional approach, but their application has so far been limited to relatively few genera. In light of this, we present here the first characterization of species and strains of the genus Phormidium Kutz. based on the cpcB-IGS-cpcA locus of the phycocyanin operon. In phylogenetic analyses using deduced amino acid sequences of the cpcB-cpcA regions, Phormidium was found to be polyphyletic. This analysis appeared to be dominated by the cpcB region, which is characterized by a relatively high percentage of informative substitutions. The percentage of variable positions within the cpcB-IGS-cpcA locus overall was 16.5%, thereby indicating a level of divergence remarkably higher than that reported for Nodularia and Arthrospira in previous studies relying on cpcB-IGS-cpcA. Further, alignment of informative nucleotide substitutions in the cpcB-IGS-cpcA sequences revealed a mosaic distribution, which may be indicative of genetic recombination events. Finally, the length and sequences of the IGS region alone proved useful as markers to differentiate the cyanobacterial genus Phormidium. However, whether the IGS region per se is sufficiently discriminatory to differentiate between Phormidium species or even strains requires further investigation using newly identified Phormidium sequence data

Molecular and phylogenetic characterization of two species of the genus Nostoc (Cyanobacteria) based on the cpcB-IGS-cpcA locus of the phycocyanin operon

Traditionally, the taxonomy of the genus Nostoc is based on morphological and physiological characters. The extreme morphological variability of the Nostoc species, due to their life cycle and environmental conditions, hampers the correct identification of the individual species. This is also one of the reasons for the disputed taxonomic positions and relationships between the genera Anabaena–Aphanizomenon as well as between Anabaena–Nostoc. Therefore, it is necessary to use additional markers for development of a polyphasic classification system of order Nostocales. In light of this, we here present the first molecular and phy-logenetic characterization of two species of the genus Nostoc (Nostoc linckia and Nostoc punctiforme) based on the cpcB-IGS-cpcA locus of the phycocyanin oper-on. The phylogenetic position of these two species within order Nostocales as well as within division Cyanobacteria has been determined. Our results indicate that genus Nostoc is heterogeneous. Analysis of the IGS region between cpcB and cpcA showed that Nostoc and Anabaena are distinct genera. Reported molecular and phylogenetic data will be useful to solve other problematic points in the tax-onomy of genera Aphanizomenon, Anabaena and Nostoc

Molecular and phylogenetic characterization of Phormidium species (Cyanoprokaryota) using the cpcB-IGS-cpcA locus

The accurate determination of species of Cyanoprokaryota/Cyanophyceae has many important applications. These include the assessment of risk with regard to blooms in water reservoirs as well as the identification of species capable of producing valuable bioactive compounds. Commonly, Cyanoprokaryota are classified based on their morphology. However, morphological criteria are not always reliable because they may change, for example, due to environmental factors. Thus, genetic and molecular analyses are a promising additional approach, but their application has so far been limited to relatively few genera. In light of this, we present here the first characterization of species and strains of the genus Phormidium Kutz. based on the cpcB-IGS-cpcA locus of the phycocyanin operon. In phylogenetic analyses using deduced amino acid sequences of the cpcB-cpcA regions, Phormidium was found to be polyphyletic. This analysis appeared to be dominated by the cpcB region, which is characterized by a relatively high percentage of informative substitutions. The percentage of variable positions within the cpcB-IGS-cpcA locus overall was 16.5%, thereby indicating a level of divergence remarkably higher than that reported for Nodularia and Arthrospira in previous studies relying on cpcB-IGS-cpcA. Further, alignment of informative nucleotide substitutions in the cpcB-IGS-cpcA sequences revealed a mosaic distribution, which may be indicative of genetic recombination events. Finally, the length and sequences of the IGS region alone proved useful as markers to differentiate the cyanobacterial genus Phormidium. However, whether the IGS region per se is sufficiently discriminatory to differentiate between Phormidium species or even strains requires further investigation using newly identified Phormidium sequence data

Zespoły fitoplanktonu i produkcja cyjanotoksyn w wybranych nizinnych jeziorach i zbiornikach Bułgarii

One of the most evident consequences of eutrophication of waters is the progressive spreading of persistent cyanobacterial blooms. They are often accompanied by the production of cyanotoxins in concentrations, which are hazardous for human health. In this research, we analysed phytoplankton communities in four lowland water bodies, for the presence of cyanobacterial blooms and toxin production. The cyanobacterial biovolumes we found, determine three of the lowland water bodies: Onogur Reservoir (OR), Asparuhov Val Reservoir (AVR), and Srebarna Lake (SL) as “Alert Level 1” of potentially hazardous levels of cyanotoxins. Cyanobacterial biovolume exceeds the threshold value of 8 mm3 L-1 (recreational waters) in AVR and SL at the end of the summer period. In OR, we registered sustainable bloom of Microcystis spp. during the whole summer season, and extremely high average seasonal value of the total biovolume (146.5 mm3 L-1). Micro-cystins were reported in all four analysed water bodies, with the highest concentration in OR (6 µg L-1). Cylindrospermopsin was detected in AVR and OR, while saxitoxins were in AVR and SL. The concentrations of cyanotoxins do not exceed the guideline values in recreational waters. However, the increased biovolumes of cyanobacteria are a signal that in three of the analysed water bodies, monitoring is recommended at the levels of cyanotoxins during the summer period.Najbardziej widocznym efektem eutrofizacji wód są coraz obszerniejsze i dłużej utrzymujące się zakwity sinic. Często towarzyszy im produkcja cyjanotoksyn w stężeniach niebezpiecznych dla zdrowia człowieka. W niniejszej pracy analizowaliśmy zespoły fitoplanktonu w czterech nizinnych zbiornikach wodnych pod kątem występowania zakwitów sinicowych i produkcji toksyn. Na podstawie badań bioobjętości sinic określono stopień potencjalnego ryzyka związanego z produkcją niebezpiecznych stężeń cyjanotoksyn w dwóch zbiornikach Onogur (OR) i Asparuhov Val (AVR) oraz w jeziorze Srebarna (SL). Stopień ryzyka w tych akwenach określono na poziomie alarmowym 1 "Alert Level 1". Pod koniec okresu letniego w AVR i SL bioobjętość sinic przekroczyła wartość progową 8 mm3 L-1 (dla wód rekreacyjnych). W OR odnotowaliśmy stały zakwit Microcystis spp. przez cały sezon letni i wyjątkowo wysoką średnią sezonową wartość całkowitej bioobjętości (146,5 mm3 L-1). Mikrocystyny wykryto we wszystkich czterech badanych zbiornikach wodnych, przy czym najwyższe stężenie odnotowano w OR (6 µg L-1). Cylindrospermopsynę wykryto w AVR i OR, natomiast saksytoksyny - w AVR i SL. Stwierdzone stężenia cyjanotoksyn nie przekraczają wartości dopuszczalnych w wodach rekreacyjnych. Jednak zwiększone bioobjętości sinic wskazują, że w trzech z czterech analizowanych zbiorników wodnych należałoby monitorować poziom cyjanotoksyn w okresie letnim

Karyotypic differences and evolutionary tendencies of some species from the subgenus Obliquodesmus Mlad. of genus Scenedesmus Meyen (Chlorophyta, Chlorococcales)

Karyotype structures of Scenedesmus acuminatus (Lagerch.) Chod. and Scenedesmus pectinatus Meyen are compared. The karyotype of S. acuminatus (n = 5) is described for the first time. It reveals four large metacentric and one large submeta centric chromosomes (4M + 1SM). The established karyotype differences have been helpful in clarifying the taxonomic position of these two species. The cytological analyses of other related clonal cultures suggest an evolutionary transition from S. pectinatus towards S. regularis through S. pectinatus f. regularis, which correlates with the morphological data about their variability. These results are discussed from the cytogenetic, morphological and evolutionary point of view. On the basis of the karyotypic analysis, it was confirmed that from a taxonomic point of view S. pectinalus, S. acuminatus and S. regularis are separate biological species

Study on freshwater algal flora on the territory of the Bulgarka Nature Park

The study presents data on the diversity of freshwater algal flora on the territory of the Bulgarka Nature Park. One hundred ninety-four species, belonging to 11 divisions were identified. The conservation value of the identified species was assessed

Phylogenetic Relationships of Some Filamentous Cyanoprokaryotic Species

The polyphasic approach is the most progressive system that has been suggested for distinguishing and phylogenetically classifying Cyanoprokaryota (Cyanobacteria/Cyanophyta). Several oscillatorialean genera ( Lyngbya, Phormidium, Plectonema , and Leptolyngbya ) have problematic phylogenetic position and taxonomic state because of their heterogeneity and polyphyletic nature. To accurately resolve the phylogenetic relationship of some filamentous species ( Nodosilinea bijugata, Phormidium molle, Phormidium papyraceum ), we have performed phylogenetic analyses based on 16S rRNA gene and the phycocyanin Operon (PC-IGS) by using maximum-likelihood (ML) tree inference methods. These analyses were combined with morphological re-evaluation. Our phylogenetic analyses support the taxonomic separation of genus Nodosilinea from the polyphyletic genus Leptolyngbya. Investigated Nodosilinea strains always formed a coherent genetic cluster supported with a high bootstrap value. The molecular phylogeny confirmed also the monophyly of the Wilmottia group. In addition, data reveal that although P. papyraceum is morphologically similar to Wilmottia murrayi , this species is genetically distinct. Strains from the newly formed genus Phormidesmis and some Phormidium priestleyi strains were clustered in a separate clade different from the typical Phormidium species, but without strong bootstrap support

Natural Xylooligosaccharides Exert Antitumor Activity via Modulation of Cellular Antioxidant State and TLR4

It has been recently proven that xylooligosaccharides (XOS) with prebiotic properties have diverse beneficial biological effects including immunomodulatory and antitumor activities. The present article focused on the chemical and biological evaluation of corn-derived commercially available XOS and aimed to elucidate their cytotoxicity and inhibitory potential against tumor cells. Spectrophotometric chemical analyses, Fourier transform infrared spectroscopy, and high-performance liquid chromatography analyses were performed. Antioxidant activity was determined by measuring the oxygen radical absorbance capacity and hydroxyl radical averting capacity. In vitro cytotoxicity assays with human cell lines derived from normal and tumor tissues, assessments of ATP production, mitochondrial membrane potential specific staining, cytokine assays, and molecular docking were used to evaluate the biological activity of XOS. The sample showed significant antioxidant activity, and it was determined that most xylose oligomers in it are composed of six units. XOS exhibited antitumor activity with pronounced inhibitory effect on lysosomes, but mitochondrial functionality was also affected. The production of proinflammatory cytokines by lipopolysaccharide-stimulated U-937 cells was reduced by XOS treatment, which suggested the involvement of Toll-like receptor 4 (TLR4)-mediated signaling in the mechanism of XOS action. Molecular docking analyses confirmed the potential inhibitory interaction between the sample and TLR4. In addition, XOS treatment had significant tumor-cell-specific influence on the glutathione antioxidant system, affecting its balance and thus contributing to the inhibition of cellular viability. The present study elucidated the tumor-inhibitory potential of commercially available XOS that could be utilized in pharmaceutical and food industry providing disease-preventive and therapeutic benefits