The green algae of the genus Ancylonema, which belong to the zygnematophytes, are prevalent colonizers of glaciers worldwide. They display a striking reddish-brown pigmentation in their natural environment, due to vacuolar compounds related to gallic acid. This pigmentation causes glacier darkening when these algae bloom, leading to increased melting rates. The Ancylonema species known so far are true psychrophiles, which hinders experimental work and limits our understanding of these algae. For instance, the biosynthesis, triggering factors, and biological function of Ancylonema's secondary pigments remain unknown. In this study, we introduce a mesophilic Ancylonema species, A. palustre sp. nov., from temperate moorlands. This species forms the sister lineage to all known psychrophilic strains. Despite its morphological similarity to the latter, it exhibits unique autecological and photophysiological characteristics. It allows us to describe vegetative and sexual cellular processes in great detail. We also conducted experimental tests for abiotic factors that induce the secondary pigments of zygnematophytes. We found that low nutrient conditions combined with ultraviolet B radiation result in vacuolar pigmentation, suggesting a sunscreen function. Our thriving, bacteria-free cultures of Ancylonema palustre will enable comparative genomic studies of mesophilic and extremophilic zygnematophytes. These studies may provide insights into how Ancylonema species colonized the world's glaciers.
- MeSH
- biologické pigmenty * metabolismus MeSH
- Chlorophyceae metabolismus genetika MeSH
- Chlorophyta metabolismus genetika MeSH
- fylogeneze * MeSH
- pigmentace MeSH
- vakuoly * metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- biologické pigmenty * MeSH
The genomes of charophyte green algae, close relatives of land plants, typically do not show signs of developmental regulation by phytohormones. However, scattered reports of endogenous phytohormone production in these organisms exist. We performed a comprehensive analysis of multiple phytohormones in Viridiplantae, focusing mainly on charophytes. We show that auxin, salicylic acid, ethylene and tRNA-derived cytokinins including cis-zeatin are found ubiquitously in Viridiplantae. By contrast, land plants but not green algae contain the trans-zeatin type cytokinins as well as auxin and cytokinin conjugates. Charophytes occasionally produce jasmonates and abscisic acid, whereas the latter is detected consistently in land plants. Several phytohormones are excreted into the culture medium, including auxin by charophytes and cytokinins and salicylic acid by Viridiplantae in general. We note that the conservation of phytohormone biosynthesis and signaling pathways known from angiosperms does not match the capacity for phytohormone biosynthesis in Viridiplantae. Our phylogenetically guided analysis of established algal cultures provides an important insight into phytohormone biosynthesis and metabolism across Streptophyta.
- MeSH
- biologická evoluce MeSH
- Chlorophyta metabolismus genetika MeSH
- cyklopentany metabolismus MeSH
- cytokininy * metabolismus MeSH
- ethyleny metabolismus MeSH
- fylogeneze * MeSH
- kyselina abscisová metabolismus MeSH
- kyselina salicylová metabolismus MeSH
- kyseliny indoloctové * metabolismus MeSH
- oxylipiny metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- regulátory růstu rostlin * metabolismus MeSH
- signální transdukce MeSH
- Viridiplantae metabolismus genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cyklopentany MeSH
- cytokininy * MeSH
- ethylene MeSH Prohlížeč
- ethyleny MeSH
- jasmonic acid MeSH Prohlížeč
- kyselina abscisová MeSH
- kyselina salicylová MeSH
- kyseliny indoloctové * MeSH
- oxylipiny MeSH
- regulátory růstu rostlin * MeSH
Marine algae are central to global carbon fixation, and their productivity is dictated largely by resource availability. Reduced nutrient availability is predicted for vast oceanic regions as an outcome of climate change; however, there is much to learn regarding response mechanisms of the tiny picoplankton that thrive in these environments, especially eukaryotic phytoplankton. Here, we investigate responses of the picoeukaryote Micromonas commoda, a green alga found throughout subtropical and tropical oceans. Under shifting phosphate availability scenarios, transcriptomic analyses revealed altered expression of transfer RNA modification enzymes and biased codon usage of transcripts more abundant during phosphate-limiting versus phosphate-replete conditions, consistent with the role of transfer RNA modifications in regulating codon recognition. To associate the observed shift in the expression of the transfer RNA modification enzyme complement with the transfer RNAs encoded by M. commoda, we also determined the transfer RNA repertoire of this alga revealing potential targets of the modification enzymes. Codon usage bias was particularly pronounced in transcripts encoding proteins with direct roles in managing phosphate limitation and photosystem-associated proteins that have ill-characterized putative functions in "light stress." The observed codon usage bias corresponds to a proposed stress response mechanism in which the interplay between stress-induced changes in transfer RNA modifications and skewed codon usage in certain essential response genes drives preferential translation of the encoded proteins. Collectively, we expose a potential underlying mechanism for achieving growth under enhanced nutrient limitation that extends beyond the catalog of up- or downregulated protein-encoding genes to the cell biological controls that underpin acclimation to changing environmental conditions.
- Klíčová slova
- codon usage, green algae, marine primary production, nutrient limitation, tRNA modification,
- MeSH
- Chlorophyta * genetika metabolismus MeSH
- fosfáty metabolismus MeSH
- kodon genetika metabolismus MeSH
- proteosyntéza MeSH
- RNA transferová genetika metabolismus MeSH
- využití kodonu * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- fosfáty MeSH
- kodon MeSH
- RNA transferová MeSH
In this work, we used splenocytes from healthy mice to study the effects of the two most commonly used cell culture media (A, B) with different compositions of redox reagents. The incubation of cells for 24 h resulted in a significant decrease in viability and metabolic activity of splenocytes, and the negative effects of incubation in medium B were more pronounced. In standard conditions, oxidative stress in cells was manifested by reduced mitochondrial potential, and this effect correlated with the transition of 58.3% of cells to the early stage of apoptosis under reducing conditions of medium A and up to 66.1% of cells under super-reducing conditions in medium B, suggesting altered cell physiology. High levels of ROS/RNS activated transcription factor Nrf2, superoxide dismutase 1, and catalase. The higher mRNA levels of these genes were under the conditions of medium B, whose super-reducing environment in combination with the environment of conventional incubators proved to be less suitable for the cells compared to medium A. Treatment of the cells with a lower concentration (10 µg/ml) of oleoresin obtained from the microalga H. pluvialis partially eliminated the negative effects of cultivation. Higher concentration of oleoresin (40 µg/ml) was slightly cytotoxic, due to the significant antioxidant effect of astaxanthin, the main bioactive component of the extract, which eliminated most of the ROS/RNS acting as signalling molecules. This study shows that the standard culture conditions do not reflect the physiological in vivo cell conditions; therefore, they are not generally suitable for incubation of all cell types.
- Klíčová slova
- Heamatococcus pluvialis, Mouse spleen cells, Oleoresin, Oxidative stress, Standard culture conditions,
- MeSH
- Chlorophyta * metabolismus MeSH
- kultivační média speciální metabolismus MeSH
- mikrořasy * metabolismus MeSH
- myši MeSH
- pilotní projekty MeSH
- reaktivní formy kyslíku metabolismus MeSH
- rostlinné extrakty metabolismus MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- kultivační média speciální MeSH
- oleoresins MeSH Prohlížeč
- reaktivní formy kyslíku MeSH
- rostlinné extrakty MeSH
Photosynthesis, growth and biochemical composition of the biomass of the freshwater microalga Chlamydopodium fusiforme cultures outdoors in a thin-layer cascade were investigated. Gross oxygen production measured off-line in samples taken from the outdoor cultures was correlated with the electron transport rate estimated from chlorophyll a fluorescence measurements. According to photosynthesis measurements, a mean of 38.9 ± 10.3 mol of photons were required to release one mole of O2, which is 4.86 times higher than the theoretical value (8 photons per 1 O2). In contrast, according to the fluorescence measurements, a mean of 11.7 ± 0.74 mol of photons were required to release 1 mol of O2. These findings indicate that fluorescence-based photosynthesis rates may not be fully replace oxygen measurements to evaluate the performance of an outdoor culture. Daily gross biomass productivity was 0.3 g DW L-1 day-1 consistently for 4 days. Biomass productivity was strongly affected by the suboptimal concentration at which the culture was operated and by the respiration rate, as the substantial volume of culture was kept in the dark (about 45% of the total volume). As the cells were exposed to excessive light, the photosynthetic activity was mainly directed to the synthesis of carbohydrates in the biomass. In the morning, carbohydrate content decreased because of the dark respiration. Per contra, protein content in the biomass was lower at the end of the day and higher in the morning due to carbohydrate consumption by respiration. The data gathered in these trials are important for the future exploitation of Chlamydopodium fusiforme as a potential novel species in the field of microalgae for the production of bio-based compounds.
- Klíčová slova
- Biomass composition, Chlamydopodium fusiforme, Chlorophyll fluorescence, Microalgae, Photosynthesis,
- MeSH
- biomasa MeSH
- chlorofyl a MeSH
- Chlorophyta * metabolismus MeSH
- fotosyntéza MeSH
- kyslík metabolismus MeSH
- mikrořasy * metabolismus MeSH
- sacharidy MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- chlorofyl a MeSH
- kyslík MeSH
- sacharidy MeSH
Kleptoplasts (kP) are distinct among photosynthetic organelles in eukaryotes (i.e., plastids) because they are routinely sequestered from prey algal cells and function only temporarily in the new host cell. Therefore, the hosts of kleptoplasts benefit from photosynthesis without constitutive photoendosymbiosis. Here, we report that the euglenozoan Rapaza viridis has only kleptoplasts derived from a specific strain of green alga, Tetraselmis sp., but no canonical plastids like those found in its sister group, the Euglenophyceae. R. viridis showed a dynamic change in the accumulation of cytosolic polysaccharides in response to light-dark cycles, and 13C isotopic labeling of ambient bicarbonate demonstrated that these polysaccharides originate in situ via photosynthesis; these data indicate that the kleptoplasts of R. viridis are functionally active. We also identified 276 sequences encoding putative plastid-targeting proteins and 35 sequences of presumed kleptoplast transporters in the transcriptome of R. viridis. These genes originated in a wide range of algae other than Tetraselmis sp., the source of the kleptoplasts, suggesting a long history of repeated horizontal gene transfer events from different algal prey cells. Many of the kleptoplast proteins, as well as the protein-targeting system, in R. viridis were shared with members of the Euglenophyceae, providing evidence that the early evolutionary stages in the green alga-derived secondary plastids of euglenophytes also involved kleptoplasty.
- Klíčová slova
- endosymbiosis, euglenozoa, horizontal gene transfer, kleptoplasty, plastid evolution,
- MeSH
- Chlorophyta * genetika metabolismus MeSH
- Eukaryota genetika MeSH
- fotosyntéza * genetika MeSH
- fylogeneze MeSH
- plastidy genetika metabolismus MeSH
- symbióza genetika MeSH
- transkriptom MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In vitro ACE-1 inhibitory peptides were characterised previously from a number of microalgal species including Spirulina platensis (peptide IAPG), Chlorella vulgaris (peptides FDL, AFL, VVPPA), Isochrysis galbana (peptide YMGLDLK), Chlorella sorokiniana (peptides IW and LW) and indeed Nannochloropsis oculata (peptides GMNNLTP and LEQ). The isolation of protein from Nannochloropsis oculata using a combination of ammonium salt precipitation and xylanase treatment of resulting biomass combined with molecular weight cut off filtration to produce a permeate and characterisation of bioactive peptides is described. The Angiotensin-1-converting enzyme (ACE-1) IC50 value for the generated permeate fraction was 370 µg/mL. Ninety-five peptide sequences within the permeate fraction were determined using mass spectrometry and eight peptides were selected for chemical synthesis based on in silico analysis. Synthesized peptides were novel based on a search of the literature and relevant databases. In silico, simulated gastrointestinal digestion identified further peptides with bioactivities including ACE-1 inhibitory peptides and peptides with antithrombotic and calcium/calmodulin-dependent kinase II (CAMKII) inhibition. This work highlights the potential of Nannochloropsis oculata biomass as both a protein and bioactive peptide resource, which could be harnessed for use in the development of functional foods and feeds.
- Klíčová slova
- Angiotensin Converting Enzyme-1 (ACE-1), Nannochloropsis oculata, functional foods, health, in silico analysis, metabolic syndrome, microalgae, pro-peptides, protein hydrolysates,
- MeSH
- Chlorella vulgaris * metabolismus MeSH
- Chlorophyta * metabolismus MeSH
- hmotnostní spektrometrie MeSH
- inhibitory ACE farmakologie chemie MeSH
- peptidy chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- inhibitory ACE MeSH
- peptidy MeSH
Excessive osteoclast differentiation and/or bone resorptive function causes a gradual loss of bone, leading to the pathogenesis of bone diseases such as osteoporosis (OP). In this study, a sulfated glucuronorhamnoxylan polysaccharide (designated SPS-CF) of the green alga Capsosiphon fulvescens was evaluated for anti-osteoporotic activity using osteoclastic cells differentiated from RAW264.7 macrophages by receptor activator of NF-κB ligand (RANKL) treatment and ovariectomized (OVX) female mice as a postmenopausal OP model. With negligible cytotoxicity, SPS-CF (50 μg/mL) significantly suppressed tartrate-resistant acid phosphatase (TRAP) activity, actin ring formation, and expression of matrix metalloproteinase 9 (MMP-9), cathepsin K, TRAF6, p-Pyk2, c-Cbl, c-Src, gelsolin, carbonic anhydrase II (CA II), and integrin β3, indicating that SPS-CF inhibits the differentiation and bone resorptive function of osteoclasts. Removal of sulfate groups from SPS-CF abolished its anti-osteoclastogenic activities, demonstrating that sulfate groups are critical for its activity. Oral administration of SPS-CF (400 mg/kg/day) to OVX mice significantly augmented the bone mineral density (BMD) and serum osteoprotegerin (OPG)/RANKL ratio. These results demonstrated that SPS-CF exerts significant anti-osteoporotic activity by dampening osteoclastogenesis and bone resorption via downregulation of TRAF6-c-Src-Pyk2-c-Cbl-gelsolin signaling and augmentation of serum OPG/RANKL ratios in OVX mice, suggesting that SPS-CF can be a novel anti-osteoporotic compound for treating postmenopausal OP.
- Klíčová slova
- Anti-osteoporosis, Capsosiphon fulvescens, Sulfated polysaccharide, Ulvan polysaccharide,
- MeSH
- buněčná diferenciace MeSH
- Chlorophyta * metabolismus MeSH
- faktor 6 asociovaný s receptory TNF metabolismus MeSH
- fokální adhezní kinasa 2 metabolismus MeSH
- gelsolin metabolismus MeSH
- kyselá fosfatasa rezistentní k tartarátu metabolismus MeSH
- myši MeSH
- NF-kappa B metabolismus MeSH
- osteoporóza * farmakoterapie MeSH
- resorpce kosti * farmakoterapie MeSH
- sírany metabolismus MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- faktor 6 asociovaný s receptory TNF MeSH
- fokální adhezní kinasa 2 MeSH
- gelsolin MeSH
- kyselá fosfatasa rezistentní k tartarátu MeSH
- NF-kappa B MeSH
- sírany MeSH
The Metabolic Scaling Theory (MST), hypothesizes limitations of resource-transport networks in organisms and predicts their optimization into fractal-like structures. As a result, the relationship between population growth rate and body size should follow a cross-species universal quarter-power scaling. However, the universality of metabolic scaling has been challenged, particularly across transitions from bacteria to protists to multicellulars. The population growth rate of unicellulars should be constrained by external diffusion, ruling nutrient uptake, and internal diffusion, operating nutrient distribution. Both constraints intensify with increasing size possibly leading to shifting in the scaling exponent. We focused on unicellular algae Micrasterias. Large size and fractal-like morphology make this species a transitional group between unicellular and multicellular organisms in the evolution of allometry. We tested MST predictions using measurements of growth rate, size, and morphology-related traits. We showed that growth scaling of Micrasterias follows MST predictions, reflecting constraints by internal diffusion transport. Cell fractality and density decrease led to a proportional increase in surface area with body mass relaxing external constraints. Complex allometric optimization enables to maintain quarter-power scaling of population growth rate even with a large unicellular plan. Overall, our findings support fractality as a key factor in the evolution of biological scaling.
In the last decade, it has become evident that complex mixtures of cyanobacterial bioactive substances, simultaneously present in blooms, often exert adverse effects that are different from those of pure cyanotoxins, and awareness has been raised on the importance of studying complex mixtures and chemical interactions. We aimed to investigate cytotoxic and genotoxic effects of complex extracts from laboratory cultures of cyanobacterial species from different orders (Cylindrospermopsis raciborskii, Aphanizomenon gracile, Microcystis aeruginosa, M. viridis, M. ichtyoblabe, Planktothrix agardhii, Limnothrix redekei) and algae (Desmodesmus quadricauda), and examine possible relationships between the observed effects and toxin and retinoic acid (RA) content in the extracts. The cytotoxic and genotoxic effects of the extracts were studied in the human hepatocellular carcinoma HepG2 cell line, using the MTT assay, and the comet and cytokinesis-block micronucleus (cytome) assays, respectively. Liquid chromatography electrospray ionization mass spectrometry (LC/ESI-MS) was used to detect toxins (microcystins (MC-LR, MC-RR, MC-YR) and cylindrospermopsin) and RAs (ATRA and 9cis-RA) in the extracts. Six out of eight extracts were cytotoxic (0.04-2 mgDM/mL), and five induced DNA strand breaks at non-cytotoxic concentrations (0.2-2 mgDM/mL). The extracts with genotoxic activity also had the highest content of RAs and there was a linear association between RA content and genotoxicity, indicating their possible involvement; however further research is needed to identify and confirm the compounds involved and to elucidate possible genotoxic effects of RAs.
- Klíčová slova
- algae, chemical analysis, complex mixtures, cyanobacteria, cyanotoxins, cytotoxicity, extracts, genotoxicity, microcystins, retinoic acids,
- MeSH
- alkaloidy izolace a purifikace toxicita MeSH
- buňky Hep G2 MeSH
- Chlorophyta metabolismus MeSH
- chromatografie kapalinová MeSH
- hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
- kometový test MeSH
- lidé MeSH
- mikrocystiny izolace a purifikace toxicita MeSH
- mikrojaderné testy MeSH
- mikrojádra chromozomálně defektní chemicky indukované MeSH
- poškození DNA * MeSH
- sinice metabolismus MeSH
- tandemová hmotnostní spektrometrie MeSH
- toxiny kmene Cyanobacteria MeSH
- tretinoin izolace a purifikace toxicita MeSH
- viabilita buněk účinky léků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- alkaloidy MeSH
- cylindrospermopsin MeSH Prohlížeč
- microcystin MeSH Prohlížeč
- mikrocystiny MeSH
- toxiny kmene Cyanobacteria MeSH
- tretinoin MeSH
