Assessment of the Tolerance of a Chlorophyte Desmodesmus to CuO-NP for Evaluation of the Nanopollution Bioremediation Potential of This Microalga.

Broad application of CuO nanoparticles (CuO-NP) for industrial and household purposes leads to a continuous increase in their discharge to, and, hence, ever-increasing environmental hazards for aquatic ecosystems. Microalgae-based technologies hold promise for bioremediation of diverse hazardous micropollutants (HMP), including NP, from wastewater. In this study, we tested the ability of the green microalga Desmodesmus sp. to accumulate CuO-NP or their components. We also assessed the tolerance of this microalga to the environmentally relevant concentrations of CuO-NP. Using scanning electron microscopy, we demonstrated that the average size of CuO-NP was 50-100 nm, and their purity was confirmed with elemental composition analysis. Tests of the colloidal suspensions of CuO-NP showed that the hydrodynamic diameter of CuO-NP and their aggregates was below 100 nm. Flow cytometry analysis showed that CuO-NP at a concentration of 100 µg L-1 slightly inhibited the viability of microalgae cells and led to an increase in their oxidative stress. The assessment of the condition of photosystem II showed that CuO-NP exert a multifaceted effect on the photosynthetic apparatus of Desmodesmus sp., depending on the concentration of and the exposure to the CuO-NP. Desmodesmus sp. turned to be relatively tolerant to CuO-NP. In addition, the ICP-MS method revealed increased bioaccumulation of copper by microalgae cells in the experimental groups. The outcomes of this study indicate that the Desmodesmus sp. has a significant potential for bioremoval of the copper-based nanostructured HMP from an aquatic environment.

Identification of the Channelrhodopsin Genes in the Green and Cryptophytic Algae from the White and Black Seas.

Due to the unique capability of modulating cell membrane potential upon photoactivation, channelrhodopsins of green (Chlorophyta) and cryptophytic (Cryptophyta) algae are widely employed in optogenetics, a modern method of light-dependent regulation of biological processes. To enable the search for new genes perspective for optogenetics, we have developed the PCR tests for the presence of genes of the cation and anion channelrhodopsins. Six isolates of green algae Haematococcus and Bracteacoccus from the White Sea region and 2 specimens of Rhodomonas sp. (Cryptophyta) from the regions of White and Black Seas were analyzed. Using our PCR test we have demonstrated the known Haematococcus rhodopsin genes and have discovered novel rhodopsin genes in the genus of Bracteacoccus. Two distantly homologous genes of anion channelrhodopsins were also identified in the cryptophytic Rhodomonas sp. from the White and Black Seas. These results indicate that the developed PCR tests might be useful tool for a broad-range screening of the Chlorophyta and Cryptophyta algae to identify unique channelrhodopsin genes.

Combined Impact of Magnetic Force and Spaceflight Conditions on Escherichia coli Physiology.

Changes in bacterial physiology caused by the combined action of the magnetic force and microgravity were studied in Escherichia coli grown using a specially developed device aboard the International Space Station. The morphology and metabolism of E. coli grown under spaceflight (SF) or combined spaceflight and magnetic force (SF + MF) conditions were compared with ground cultivated bacteria grown under standard (control) or magnetic force (MF) conditions. SF, SF + MF, and MF conditions provided the up-regulation of Ag43 auto-transporter and cell auto-aggregation. The magnetic force caused visible clustering of non-sedimenting bacteria that formed matrix-containing aggregates under SF + MF and MF conditions. Cell auto-aggregation was accompanied by up-regulation of glyoxylate shunt enzymes and Vitamin B12 transporter BtuB. Under SF and SF + MF but not MF conditions nutrition and oxygen limitations were manifested by the down-regulation of glycolysis and TCA enzymes and the up-regulation of methylglyoxal bypass. Bacteria grown under combined SF + MF conditions demonstrated superior up-regulation of enzymes of the methylglyoxal bypass and down-regulation of glycolysis and TCA enzymes compared to SF conditions, suggesting that the magnetic force strengthened the effects of microgravity on the bacterial metabolism. This strengthening appeared to be due to magnetic force-dependent bacterial clustering within a small volume that reinforced the effects of the microgravity-driven absence of convectional flows.

Chilling Upregulates Expression of the PsbS and LhcSR Genes in the Chloroplasts of the Green Microalga Lobosphaera incisa IPPAS C-2047.

Non-photochemical quenching (NPQ) of excited chlorophyll states is essential for protecting the photosynthetic apparatus (PSA) from the excessive light-induced damage in all groups of oxygenic photosynthetic organisms. The key component of the NPQ mechanism in green algae and some other groups of algae and mosses is the LhcSR protein of the light harvesting complex (LHC) protein superfamily. In vascular plants, LhcSR is replaced by PsbS, another member of the LHC superfamily and a subunit of photosystem II (PSII). PsbS also performs the photoprotective function in mosses. For a long time, PsbS had been believed to be nonfunctional in green algae, although the corresponding gene was discovered in the genome of these organisms. The first evidence of the PsbS accumulation in the model green alga Chlamydomonas reinhardtii in response to the increase in irradiance was obtained only six years ago. However, the observed increase in the PsbS content was short-termed (on an hour-timescale). Here, we report a significant (more than three orders of magnitude) and prolonged (four days) upregulation of PsbS expression in response to the chilling-induced high-light stress followed by a less significant (~ tenfold) increase in the PsbS expression for nine days. This is the first evidence for the long-term upregulation of the PsbS expression in green alga (Chlorophyta) in response to stress. Our data indicate that the role of PsbS in the PSA of Chlorophyta is not limited to the first-line defense against stress, as it was previously assumed, but includes full-scale participation in the photoprotection of PSA from the environmental stress factors.

Cationic penetrating antioxidants switch off Mn cluster of photosystem II in situ.

Mitochondria-targeted antioxidants (also known as 'Skulachev Ions' electrophoretically accumulated by mitochondria) exert anti-ageing and ROS-protecting effects well documented in animal and human cells. However, their effects on chloroplast in photosynthetic cells and corresponding mechanisms are scarcely known. For the first time, we describe a dramatic quenching effect of (10-(6-plastoquinonyl)decyl triphenylphosphonium (SkQ1) on chlorophyll fluorescence, apparently mediated by redox interaction of SkQ1 with Mn cluster in Photosystem II (PSII) of chlorophyte microalga Chlorella vulgaris and disabling the oxygen-evolving complex (OEC). Microalgal cells displayed a vigorous uptake of SkQ1 which internal concentration built up to a very high level. Using optical and EPR spectroscopy, as well as electron donors and in silico molecular simulation techniques, we found that SkQ1 molecule can interact with Mn atoms of the OEC in PSII. This stops water splitting giving rise to potent quencher(s), e.g. oxidized reaction centre of PSII. Other components of the photosynthetic apparatus proved to be mostly intact. This effect of the Skulachev ions might help to develop in vivo models of photosynthetic cells with impaired OEC function but essentially intact otherwise. The observed phenomenon suggests that SkQ1 can be applied to study stress-induced damages to OEC in photosynthetic organisms.

Mössbauer spectroscopic study of transformations of iron species by the cyanobacterium Arthrospira platensis (formerly Spirulina platensis).

In the present paper, Mössbauer spectroscopic studies of dry biomass samples of the cyanobacterium Arthrospira platensis (formerly known as Spirulina platensis) were performed with regard to metabolic iron accumulation. 57Fe Mössbauer parameters of iron in the biomass correspond to ferrihydrite. Spectra of iron hydroxides in A. platensis biomass differ from those of iron complexes with ethylenediaminetetraacetic acid injected to Zarrouk culture medium. The limit of saturation of A. platensis trichomes with iron in the form of ferrihydrite was found to be 5 µg/ml (0.09 µmol/ml) Fe in the culture medium. Conglomerates precipitated in the medium at higher iron concentrations also contain ferrihydrite but the ratio of the crystal lattice forms is different from that in the biomass.

Simple and versatile method for creation of non-leaching antimicrobial surfaces based on cross-linked alkylated polyethyleneimine derivatives.

Novel quaternized polyethyleneimine and cross-linked polyethyleneimine derivatives have been synthesized using both traditional and microwave-assisted techniques to create antimicrobial coatings, with octyl, dodecyl, or hexadecyl bromides as alkylating agent and various bifunctional electrophiles as cross-linkers. Quaternization has been performed using methyl iodide or dimethyl sulfate; it has been shown that methyl iodide has no advantages over dimethyl sulfate. Antimicrobial activity of the polymers against Gram-positive (S. aureus) and Gram-negative (P. aeruginosa) bacteria has been evaluated. Antimicrobial activity declines with increase in the alkylating agent chain length. Equimolar ratio of the alkylating agent and the primary amino groups in polyethyleneimine is optimal. Although cross-linking decreases the antimicrobial activity of quaternized polyethyleneimines, it improves their "non-leaching" properties (i.e. minimizes undesirable water washout of the polymeric coatings).

Similarity and diversity of the Desmodesmus spp. microalgae isolated from associations with White Sea invertebrates.

Similarity and diversity of the phenotype and nucleotide sequences of certain genome loci among the single-celled microalgae isolated from White Sea benthic invertebrates were studied to extend the knowledge of oxygenic photoautotrophs forming microbial communities associated with animals. We compared four Desmodesmus isolates (1Hp86E-2, 1Pm66B, 3Dp86E-1, 2Cl66E) from the sponge Halichondria panicea, trochophore larvae of the polychaete Phyllodoce maculata, and the hydroids Dynamena pumila and Coryne lovenii, respectively. The microalgae appeared to be very similar featuring the phenotypic and genetic traits characteristics of unicellular representatives of the genus Desmodesmus. At the same time, isolates from different animal species displayed certain differences in (i) the epistructure morphology; (ii) type and number of the inclusions such as interthylakoid starch grains and cytoplasmic oil bodies and (iii) fatty acid composition; in Desmodesmus sp. 1Hp86E-2, these differences were most pronounced. Phylogenetic analysis based on ITS1-5.8S rRNA-ITS2 and rbcL sequences showed that all isolates studied differ from known classified representatives of Desmodesmus combining a deletion in the conservative 5.8S rRNA gene and long AC-microsatellite repeats in the ITS1 whereas 1Hp86E-2 represented a distinct branch within this group.

Purification and characterization of windmill palm tree (Trachycarpus fortunei) peroxidase.

High peroxidase activity was demonstrated to be present in the leaf of several species of cold-resistant palms. Histochemical studies of the leaf of windmill palm tree (Trachycarpus fortunei) showed the peroxidase activity to be localized in hypoderma, epidermis, cell walls, and conducting bundles. However, chlorophyll-containing mesophyll cells had no peroxidase at all. The leaf windmill palm tree peroxidase (WPTP) was purified to homogeneity and had a specific activity of 6230 units/mg, RZ = 3.0, a molecular mass of 50 kDa, and an isoelectric point of pI 3.5. The electronic spectrum of WPTP with a Soret band at 403 nm was typical of plant peroxidases. The N-terminal amino acid sequence of WPTP was determined. The substrate specificity of WPTP was distinct from that of other palm peroxidases, and the best substrate for WPTP was 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid). The palm peroxidase showed an unusually high stability at elevated temperatures and high concentrations of guanidine.