Nanoscale zero valent iron (nZVI) is used to remediate aquifers polluted by organochlorines or heavy metals and was also suggested to eliminate harmful algal blooms. nZVI can therefore affect microorganisms in the vicinity of the application area, including microalgae. However, studies on early transcriptomic effects of microalgae after exposure to nZVI are rare. Here, we described the early physiological and transcriptomic response of the freshwater ecological indicator green microalga, Raphidocelis subcapitata ATCC 22662, to 100 mg/L of reactive nZVI and non-reactive nano-magnetite (nFe3O4). The combined effect of shading and the release of total iron from nZVI posed a short-term inhibition effect leading to 15 % of deformed cells and cytosol leakage, while cells viability increased after 24 h. nZVI triggered a more pronounced transcriptomic response with (7380 differentially expressed genes [DEGs]) compared to nFe3O4 (4601 DEGs) after 1 h. nZVI, but not nFe3O4 increased the expression of genes function in DNA repair and replication, while deactivated carbohydrate-energy metabolisms, mitochondria signaling, and transmembrane ion transport. This study highlights an early fate assessment of algal cells under nZVI and nFe3O4 exposure using next-generation risk assessment methods and will serve as valuable information for safe and sustainable application of nZVI in water remediation.

• Klíčová slova
• DNA repair and replication, Iron stress, Microalgae, NZVI, Non-photochemical quenching, RNA-seq,
• MeSH
• chemické látky znečišťující vodu * toxicita   MeSH
• Chlorophyceae účinky léků   genetika   MeSH
• mikrořasy * účinky léků   MeSH
• stanovení celkové genové exprese MeSH
• transkriptom * účinky léků   MeSH
• železo * toxicita   chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chemické látky znečišťující vodu * MeSH
• železo * MeSH

Dictyosphaerium chlorelloides is a green microalga from the Chlorella clade that produces highly viscous exocellular polysaccharides. The cell wall polysaccharides of this alga have not been studied in detail. In this article, water-soluble polysaccharides from D. chlorelloides biomass were extracted with hot water and purified by preparative chromatography. The composition, structural features and molecular masses of subsequently eluted fractions F1, F2, F3, F4 and F5 (minor) were determined. Three high-yield products F1, F3 and F4 consisted mainly of galactopyranosyl, 2-O-methyl-galactopyranosyl, rhamnopyranosyl and mannopyranosyl units at different proportions, while F2 was rich in glucose. Immunoactivity of these fractions was evidenced in a mixed population of immune cells derived from mice spleens after incubation with polysaccharides by flow cytometry, MTT and Immunospot assays. These fractions, except F2, demonstrated selective immunostimulant activity, and the F1 fraction induced the most potent effect, closely followed by the F3 and F4 fractions. The in vivo mechanism of their action is associated with the activation of innate immunity and shapes the immune response to the Th1 type.

• Klíčová slova
• Dictyosphaerium chlorelloides, Immunomodulating activity, Microalgae biomass, Structure, Water-soluble polysaccharides,
• MeSH
• adjuvancia imunologická farmakologie   chemie   izolace a purifikace   MeSH
• buněčná stěna * chemie   MeSH
• Chlorophyta chemie   MeSH
• mikrořasy * chemie   MeSH
• myši inbrední BALB C MeSH
• myši MeSH
• polysacharidy * farmakologie   chemie   izolace a purifikace   MeSH
• slezina cytologie   účinky léků   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• adjuvancia imunologická MeSH
• polysacharidy * MeSH

The extremophilic unicellular red microalga Galdieria sulphuraria (Cyanidiophyceae) is able to grow autotrophically, or mixo- and heterotrophically with 1% glycerol as a carbon source. The alga divides by multiple fission into more than two cells within one cell cycle. The optimal conditions of light, temperature and pH (500 µmol photons m-2 s-1, 40 °C, and pH 3; respectively) for the strain Galdieria sulphuraria (Galdieri) Merola 002 were determined as a basis for synchronization experiments. For synchronization, the specific light/dark cycle, 16/8 h was identified as the precondition for investigating the cell cycle. The alga was successfully synchronized and the cell cycle was evaluated. G. sulphuraria attained two commitment points with midpoints at 10 and 13 h of the cell cycle, leading to two nuclear divisions, followed subsequently by division into four daughter cells. The daughter cells stayed in the mother cell wall until the beginning of the next light phase, when they were released. Accumulation of glycogen throughout the cell cycle was also described. The findings presented here bring a new contribution to our general understanding of the cell cycle in cyanidialean red algae, and specifically of the biotechnologically important species G. sulphuraria.

• Klíčová slova
• Galdieria, cell cycle, cell division, growth, light intensity, red algae, synchronization, temperature, trophic regimes,
• MeSH
• buněčný cyklus fyziologie   MeSH
• heterotrofní procesy fyziologie   MeSH
• kultivované buňky MeSH
• mikrořasy cytologie   růst a vývoj   MeSH
• Rhodophyta cytologie   růst a vývoj   MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The aim of the study was to identify the optimum cultivation conditions for the microalgal growth and lipid production of the oleaginous microalga Chlorella pyrenoidosa Chick (IPPAS C2). Moreover, an appropriate NO3- concentration in the cultivation medium for maximized lipid accumulation was determined. The experimental design involved a biphasic cultivation strategy with an initial biomass accumulating phase under optimized light (400 μmol/m2 per s), temperature (25 °C), and elevated CO2 concentration in the air mixture (3%), followed by a mid-elevated CO2 concentration (0.5%) for lipid induction. The highest lipid yields of 172.47 ± 18.1 and 179.65 ± 25.4 mg/L per day were detected for NO3- concentrations of 100 and 150 mg/L. The optimization approach presented here led not only to the maximization of lipid yield but also to the development of a biphasic cultivation strategy easily applicable to the cultivation process without the necessity for algal cell harvesting between the first and second cultivation phases.

• MeSH
• biomasa MeSH
• Chlorella růst a vývoj   metabolismus   MeSH
• dusičnany metabolismus   MeSH
• fotobioreaktory MeSH
• kultivační média metabolismus   MeSH
• lipidy biosyntéza   MeSH
• mikrořasy růst a vývoj   metabolismus   MeSH
• oxid uhličitý metabolismus   MeSH
• techniky vsádkové kultivace MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dusičnany MeSH
• kultivační média MeSH
• lipidy MeSH
• oxid uhličitý MeSH

The objective of the present study was to evaluate a potential of Schizochytrium microalga oil to alleviate possible negative effects of high-fat-high-energy diets. Forty adult male rats (Wistar Albino) were fed 7 weeks the diet containing beef tallow + evaporated sweetened milk (diet T) intended to cause mild obesity and low-grade systemic inflammation. Consequently, the animals were divided into four groups by 10 animals each and fed either the T-diet (control) or the diet containing 6% of safflower oil (S), 6% of fish oil (F) and 6% of Schizochytrium microalga oil (A), respectively, for another 7 weeks. The A-diet decreased (p < 0.05) live weight to 86% and glycaemia to 85% of control, respectively; an effect of the S- and F-diet on these markers was insignificant (p > 0.05). In comparison with control, higher (p < 0.05) deposition of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) in the epididymal adipose tissue (EAT) of the A-rats correlated with increased (p < 0.05) plasma adiponectin concentration, but it was without the effect (p > 0.05) on cellular adiponectin content in the EAT. Higher (p < 0.05) EPA+DHA deposition in the liver of the A-rats correlated with higher expression (149% of control; p < 0.05) of the gene coding for peroxisome proliferator-activated receptor gamma, and with lower expression (82% and 66%; p < 0.05) of the genes coding for adiponectin receptors AdipoR1 and AdipoR2; no relationship to the expression of receptor GPR120 was found. The A-diet did not affect amount of the nuclear fraction of the nuclear factor kappa B in the liver, but increased plasma level of anti-inflammatory cytokine TGF-β1 (p < 0.05). The presented data agree with results of other in vivo rodent and human studies, but not with literature data regarding in vitro experiments: it can be concluded that the effects of dietary oils on inflammatory markers need further investigation.

• Klíčová slova
• GPR120, NF-κB, TNF-α, adiponectin, docosahexaenoic acid,
• MeSH
• adiponektin genetika   metabolismus   MeSH
• cytokiny genetika   metabolismus   MeSH
• dieta veterinární   MeSH
• krmivo pro zvířata analýza   MeSH
• krysa rodu Rattus MeSH
• mikrořasy chemie   MeSH
• náhodné rozdělení MeSH
• NF-kappa B genetika   metabolismus   MeSH
• oleje rostlin chemie   farmakologie   MeSH
• potkani Wistar MeSH
• PPAR gama genetika   metabolismus   MeSH
• regulace genové exprese účinky léků   MeSH
• zánět farmakoterapie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• adiponektin MeSH
• cytokiny MeSH
• NF-kappa B MeSH
• oleje rostlin MeSH
• PPAR gama MeSH

A terrestrial green microalga was isolated at Ås, in Akershus County, Norway. The strain corresponded to a coccoid chlorophyte. Morphological characteristics by light and electron microscopy, in conjunction with DNA amplification and sequencing of the 18 s rDNA gene and ITS sequences, were used to identify the microalgae. The characteristics agree with those of the genus Coelastrella defined by Chodat, and formed a sister group with the recently described C. thermophila var. globulina. Coelastrella is a relatively small numbered genus that has not been observed in continental Norway before; there are no previous cultures available in collections of Norwegian strains. Gas chromatography analyses of the FAME-derivatives showed a high percentage of polyunsaturated fatty acids (44-45%) especially linolenic acid (C18:3n3; 30-34%). After the stationary phase, the cultures were able to accumulate several carotenoids as neoxanthin, pheophytin a, astaxanthin, canthaxanthin, lutein, and violaxanthin. Due to the scarcity of visual characters suitable for diagnostic purposes and the lack of DNA sequence information, there is a high possibility that species of this genus have been neglected in local environmental studies, even though it showed interesting properties for algal biotechnology.

• Klíčová slova
• 18S rDNA, Algae phylogeny, Electron microscopy, Fatty acids, ITS, Strain FGS-001,
• MeSH
• biologické pigmenty analýza   MeSH
• biotechnologie MeSH
• Chlorophyta klasifikace   cytologie   genetika   MeSH
• druhová specificita MeSH
• feofytiny analýza   MeSH
• fylogeneze * MeSH
• karotenoidy analýza   MeSH
• kyselina alfa-linolenová analýza   MeSH
• mastné kyseliny analýza   MeSH
• mikrořasy klasifikace   cytologie   genetika   izolace a purifikace   MeSH
• ribozomální DNA MeSH
• RNA ribozomální 18S genetika   MeSH
• xanthofyly MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Norsko MeSH
• Názvy látek
• astaxanthine MeSH Prohlížeč
• biologické pigmenty MeSH
• feofytiny MeSH
• karotenoidy MeSH
• kyselina alfa-linolenová MeSH
• mastné kyseliny MeSH
• neoxanthin MeSH Prohlížeč
• ribozomální DNA MeSH
• RNA ribozomální 18S MeSH
• violaxanthin MeSH Prohlížeč
• xanthofyly MeSH

The catastrophic loss of aquatic life in the Central European Oder River in 2022, caused by a toxic bloom of the haptophyte microalga Prymnesium parvum (in a wide sense, s.l.), underscores the need to improve our understanding of the genomic basis of the toxin. Previous morphological, phylogenetic, and genomic studies have revealed cryptic diversity within P. parvum s.l. and uncovered three clade-specific (types A, B, and C) prymnesin toxins. Here, we used state-of-the-art long-read sequencing and assembled the first haplotype-resolved diploid genome of a P. parvum type B from the strain responsible for the Oder disaster. Comparative analyses with type A genomes uncovered a genome-size expansion driven by repetitive elements in type B. We also found conserved synteny but divergent evolution in several polyketide synthase (PKS) genes, which are known to underlie toxin production in combination with environmental cues. We identified an approximately 20-kbp deletion in the largest PKS gene of type B that we link to differences in the chemical structure of types A and B prymnesins. Flow cytometry and electron microscopy analyses confirmed diploidy in the Oder River strain and revealed differences to closely related strains in both ploidy and morphology. Our results provide unprecedented resolution of strain diversity in P. parvum s.l. and a better understanding of the genomic basis of toxin variability in haptophytes. The reference-quality genome will enable us to better understand changes in microbial diversity in the face of increasing environmental pressures and provides a basis for strain-level monitoring of invasive Prymnesium in the future.

• Klíčová slova
• genomics, golden alga, haptophyte, harmful algal bloom, ploidy, polyketide synthase, prymnesin,
• MeSH
• fylogeneze MeSH
• haplotypy MeSH
• Haptophyta * genetika   MeSH
• mikrořasy genetika   MeSH
• mořské toxiny genetika   MeSH
• polyketidsynthasy genetika   metabolismus   MeSH
• ryby genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• mořské toxiny MeSH
• polyketidsynthasy MeSH

The alga Parachlorella kessleri, strain CCALA 255, grown under optimal conditions, is characterized by storage of energy in the form of starch rather than lipids. If grown in the complete medium, the cultures grew rapidly, producing large amounts of biomass in a relatively short time. The cells, however, contained negligible lipid reserves (1-10% of DW). Treatments inducing hyperproduction of storage lipids in P. kessleri biomass were described. The cultures were grown in the absence or fivefold decreased concentration of either nitrogen or phosphorus or sulfur. Limitation by all elements using fivefold or 10-fold diluted mineral medium was also tested. Limitation with any macroelement (nitrogen, sulfur, or phosphorus) led to an increase in the amount of lipids; nitrogen limitation was the most effective. Diluted nutrient media (5- or 10-fold) were identified as the best method to stimulate lipid overproduction (60% of DW). The strategy for lipid overproduction consists of the fast growth of P. kessleri culture grown in the complete medium to produce sufficient biomass (DW more than 10 g/L) followed by the dilution of nutrient medium to stop growth and cell division by limitation of all elements, leading to induction of lipid production and accumulation up to 60% DW. Cultivation conditions necessary for maximizing lipid content in P. kessleri biomass generated in a scale-up solar open thin-layer photobioreactor were described.

• MeSH
• biomasa MeSH
• biotechnologie MeSH
• chlorofyl analýza   metabolismus   MeSH
• Chlorophyta metabolismus   MeSH
• fotobioreaktory MeSH
• kultivační média MeSH
• lipidy biosyntéza   MeSH
• mastné kyseliny analýza   metabolismus   MeSH
• metabolismus lipidů MeSH
• mikrořasy metabolismus   MeSH
• oxid uhličitý metabolismus   MeSH
• škrob analýza   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chlorofyl MeSH
• kultivační média MeSH
• lipidy MeSH
• mastné kyseliny MeSH
• oxid uhličitý MeSH
• škrob MeSH

The purpose of the study was to test the hypothesis that the dietary oils with different content of n-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) affect plasma lipid level in rats in a different degree. The diets with 6% of fish oil (FO) and Schizochytrium microalga oil (SchO; EPA+DHA content in the diets 9.5 + 12.3 and 2.6 + 29.5% of the sum of total fatty acids, respectively) were used; the diet with 6% of safflower oil (high content of n-6 PUFA linoleic acid, 65.5%; EPA+DHA content 0.7 + 0.9%) was used as a control. The difference between FO and SchO was established only in the case of plasma triacylglycerol (TAG) level: plasma TAG of the FO-fed rats did not differ from the control rats (p > 0.05), while SchO decreased (p < 0.05) plasma TAG to 46% of the control. On the other hand, FO and SchO decreased (p < 0.05) total plasma cholesterol (TC) in rats in the same extent, to 73% of the control. Regarding the underlying mechanisms for the TC decrease, both SchO and FO up-regulated hepatic Insig-1 gene (181 and 133% of the control; p < 0.05), which tended (p = 0.15 and p = 0.19 respectively) to decrease the amount of hepatic nSREBP-2 protein (61 and 66% of the control). However, neither SchO nor FO influenced hepatic 3-hydroxy-3-methyl-glutaryl-CoA reductase gene expression (p > 0.05); SchO (but not FO) increased (p < 0.05) low-density lipoprotein receptor mRNA in the liver. It was concluded that the decrease of total plasma cholesterol might be caused by an increased cholesterol uptake from plasma into the cells (in the case of SchO), but also by other (in the present study not tested) mechanisms.

• Klíčová slova
• Insig-1, Schizochytrium, cholesterol, docosahexaenoic acid, fish oil, nSREBP-2,
• MeSH
• cholesterol krev   MeSH
• dieta MeSH
• játra chemie   metabolismus   MeSH
• krmivo pro zvířata analýza   MeSH
• krysa rodu Rattus MeSH
• mikrořasy chemie   MeSH
• náhodné rozdělení MeSH
• nenasycené mastné kyseliny chemie   metabolismus   MeSH
• oleje rostlin chemie   farmakologie   MeSH
• potkani Wistar MeSH
• protein SREBP2 genetika   metabolismus   MeSH
• regulace genové exprese účinky léků   MeSH
• rybí oleje chemie   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cholesterol MeSH
• nenasycené mastné kyseliny MeSH
• oleje rostlin MeSH
• protein SREBP2 MeSH
• rybí oleje MeSH

The water-insoluble part of Parachlorella kessleri HY1 biomass was subjected to the extraction of cell-wall polysaccharides using polar aprotic solvents (DMSO, LiCl/DMSO) and aqueous alkaline solutions (0.1, 1 and 4 mol·l-1 of NaOH). Proteins predominated in all the crude extracts and in the insoluble residues were partially removed by treatment with proteolytic enzymes (pepsin and pronase), and in some cases with the HCl/H2O2 reagent, yielding purified polysaccharide-enriched fractions. These treatments led to the solubilisation of some products in water. The composition and structure of isolated polysaccharides were characterised based on monosaccharide composition, glycosidic linkage and spectroscopic analyses. The DMSO extract contained mainly proteins, and polysaccharides were not detected. The water-soluble parts isolated from the LiCl/DMSO extract contained α-l-rhamnan, α-d-glucan and β-d-glucogalactan; the water-insoluble part contained (1 → 4)-β-d-xylan, first isolated from the biomass of green microalgae. The alkali extracts contained polysaccharides of similar structure, and also water-insoluble (1 → 4)-β-d-mannan. The insoluble part after all extractions contained α-chitin as the main polysaccharide, which was confirmed by spectroscopic methods. All these polysaccharides can play a certain role in the cell wall structure of this microalga.

• Klíčová slova
• Cell wall structure, Green microalgae, Parachlorella kessleri, Structural polysaccharides,
• MeSH
• biomasa MeSH
• buněčná stěna chemie   MeSH
• Chlorophyta * MeSH
• dimethylsulfoxid MeSH
• mikrořasy * genetika   MeSH
• peroxid vodíku analýza   MeSH
• polysacharidy chemie   MeSH
• voda analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dimethylsulfoxid MeSH
• peroxid vodíku MeSH
• polysacharidy MeSH
• voda MeSH