Magnetophoretic harvesting of freshwater microalgae using polypyrrole/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanocomposite and its reusability

A magnetophoretic harvesting agent, a polypyrrole/Fe₃O₄ magnetic nanocomposite, is proposed as a cost and energy efficient alternative to recover biomass of the microalgae Botryococcus braunii, Chlorella protothecoides, and Chlorella vulgaris from their culture media. The maximal recovery efficiency reached almost 99 % for B. braunii, 92.4 % for C. protothecoides, and 90.8 % for C. vulgaris. The maximum adsorption capacity (Q ₀) of the magnetic nanocomposite for B. braunii (63.49 mg dry biomass mg^?1 PPy/Fe₃O₄) was higher than that for C. protothecoides (43.91 mg dry biomass mg^?1 PPy/Fe₃O₄) and C. vulgaris (39.98 mg dry biomass mg^?1 PPy/Fe₃O₄). The highest harvesting efficiency for all the studied microalgae were at pH 10.0, and measurement of zeta-potential confirmed that the flocculation was induced by charge neutralization. This study showed that polypyrrole/Fe₃O₄ can be a promising flocculant due to its high efficacy, low dose requirements, short settling time, its integrity with cells, and with great potential for saving energy because of its recyclability.     

Construction of flavocytochrome <Emphasis Type="Italic">b</Emphasis><Subscript>2</Subscript>-overproducing strains of the thermotolerant methylotrophic yeast <Emphasis Type="Italic">Hansenula polymorpha</Emphasis> (<Emphasis Type="Italic">Pichia angusta</Emphasis>)

L-Lactate cytochrome c oxidoreductase (flavocytochrome b ₂, FC b ₂) from the thermotolerant methylotrophic yeast Hansenula polymorpha (Pichia angusta) is, unlike the enzyme form baker’s yeast, a thermostable enzyme potentially important for bioanalytical technologies for highly selective assays of L-lactate in biological fluids and foods. This paper describes the construction of flavocytochrome b ₂ producers with over-expression of the H. polymorpha CYB2 gene, encoding FC b ₂. The HpCYB2 gene under the control of the strong H. polymorpha alcohol oxidase promoter in a plasmid for multicopy integration was transformed into the recipient strain H. polymorpha C-105 (grc1 catX), impaired in glucose repression and devoid of catalase activity. A method was developed for preliminary screening of the transformants with increased FC b ₂ activity in permeabilized yeast cells. The optimal cultivation conditions providing for the maximal yield of the target enzyme were found. The constructed strain is a promising FC b ₂ producer characterized by a sixfold increased (to 3 μmol min^?1 mg^?1 protein in cell-free extract) activity of the enzyme.     

Long-term H<Subscript>2</Subscript> photoproduction from starch by co-culture of <Emphasis Type="Italic">Clostridium butyricum</Emphasis> and <Emphasis Type="Italic">Rhodobacter sphaeroides</Emphasis> in a repeated batch process

Objectives

To prove the possibility of efficient starch photofermentation in co-culture of heterotrophic and phototrophic bacteria over prolonged period.

Results

Repeated batch photofermentation of starch was demonstrated in co-culture Clostridium butyricum and Rhodobacter sphaeroides under microaerobic conditions. It continued 15 months without addition of new inoculum or pH regulation when using 4–5 g starch l^?1 and 0.04 g yeast extract l^?1. The complete degradation of starch without volatile fatty acids accumulation was shown in this co-culture. The average H₂ yield of 5.2 mol/mol glucose was much higher than that in Clostridium monoculture. The species composition of co-culture was studied by q-PCR assay. The concentration of Clostridium cells in prolonged co-culture was lower than in monoculture and even in a single batch co-culture. This means that Clostridia growth was significantly limited whereas starch hydrolysis still took place.

Conclusion

The prolonged repeated batch photofermentation of starch by co-culture C. butyricum and R. sphaeroides provided efficient H₂ production without accumulation of organic acids under conditions of Clostridia limitation.

     

Theoretical investigation on exciton-dissociation and charge-recombination processes of PC<Subscript>61</Subscript>BM-PTDPPSe interface

Designing and synthesizing novel electron-donor polymers with the high photovoltaic performances has remained a major challenge and hot issue in organic electronics. In this work, the exciton-dissociation (k _dis ) and charge-recombination (k _rec ) rates for the PC₆₁BM-PTDPPSe system as a promising polymer-based solar cell candidate have been theoretically investigated by means of density functional theory (DFT) calculations coupled with the non-adiabatic Marcus charge transfer model. Moreover, a series of regression analysis has been carried out to explore the rational structure–property relationship. Results reveal that the PC₆₁BM-PTDPPSe system possesses the large open-circuit voltage (0.77 V), middle-sized exiton binding energy (0.457 eV), and relatively small reorganization energies in exciton-dissociation (0.273 eV) and charge-recombination (0.530 eV) processes. With the Marcus model, the k _dis , k _rec , and the radiative decay rate (k _s ), are estimated to be 3.167×10¹¹ s^?1, 3.767×10¹⁰ s^?1, and 7.930×10⁸ s^?1 respectively in the PC₆₁BM-PTDPPSe interface. Comparably, the k _dis is as 1～3 orders of magnitude larger than the k _rec and the k _s , which indicates a fast and efficient photoinduced exciton-dissociation process in the PC₆₁BM-PTDPPSe interface.

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Graphical Abstract PTDPPSe is predicted to be a promising electron donor polymer, and the PC₆₁BM-PTDPPSe system is worthy of further device research by experiments.

     

Impact of elevated CO<Subscript>2</Subscript> in <Emphasis Type="Italic">Casuarina equisetifolia</Emphasis> rooted stem cuttings inoculated with <Emphasis Type="Italic">Frankia</Emphasis>

Impact of different levels of elevated CO ₂ on the activity of Frankia (Nitrogen-fixing actinomycete) in Casuarina equisetifolia rooted stem cuttings has been studied to understand the relationship between C. equisetifolia, Frankia and CO₂. The stem cuttings of C. equietifolia were collected and treated with 2000 ppm of Indole Butyric Acid (IBA) for rooting. Thus vegetative propagated rooted stem cuttings of C. equisetifolia were inoculated with Frankia and placed in the Open top chambers (OTC) with elevated CO₂ facilities. These planting stocks were maintained in the OTC for 12 months under different levels of elevated CO₂ (ambient control, 600 ppm, 900 ppm). After 12 months, the nodule numbers, bio mass, growth, and photosynthesis of C. equisetifolia rooted stem cuttings inoculated with Frankia were improved under 600 ppm of CO₂. The rooted stem cuttings of C. equisetifolia inoculated with Frankia showed a higher number of nodules under 900 ppm of CO₂ and cuttings without Frankia inoculation exhibited poor growth. Tissue Nitrogen (N) content was also higher under 900 ppm of CO₂ than ambient control and 600 ppm levels. The photosynthetic rate was higher (17.8 μ mol CO₂ m^?2 s^?1) in 900 ppm of CO₂ than in 600 ppm (13.2 μ mol CO₂ m^?2 s^?1) and ambient control (8.3 μ mol CO₂ m^?2 s^?1). This study showed that Frankia can improve growth, N fixation and photosynthesis of C. equietifolia rooted stem cuttings under extreme elevated CO₂ level conditions (900 ppm).     

Effect of hydrophyte thickets density on zooplankton

An experimental study on the zooplankton community in the thickets of elodea Elodea canadensis Michx. of different densities (2, 4, and 8 g/L, wet weight/L) has been conducted. It is revealed that specific cationic composition and pH and sharp daily fluctuation of oxygen concentrations is a characteristic of the water in dense thickets of plants. Changes in water chemistry and in spatial organization of the environment influence zooplankton diversity and population dynamics of some species. With an increase in density of thickets, the number of Daphnia longispina O.F. Müller decreases, while the share of predators (Cyclopidae and Polyphemus pediculus O.F. Müller) increases. The abundance of Ceriodaphnia quadrangula (O.F. Müller) increases in the presence of plants, but does not depend on the density of the thickets. The correlation between the development of Simocephalus vetulus (O.F. Müller) and Diaphanosoma brachyurum (Liévin) and water cationic composition, changing in the process of growth and senescence of plants, is revealed.     

Uncertainty of using habitat fidelity in biomonitoring based on benthic diatoms - the Raška River case study

Epilithic diatoms are frequently recommended for river biomonitoring, while much less emphasis is placed on epiphytic communities. This study considers use of epiphytic and epilithic diatom communities from the Ra?ka River in biomonitoring. A total of 212 diatom taxa were recorded in both communities. Dominant diatoms were Achnanthidium minutissimum (Kützing) Czarnecki, A. affine (Grunow) Czarnecki, A. subatomus (Hustedt) Lange-Bertalot, Amphora pediculus (Kützing) Grunow, Diatoma vulgaris Bory, Gomphonema tergestinum (Grunow) Fricke, Cocconeis placentula var. lineata (Ehrenberg) Van Heurck, Melosira varians Agardh and Navicula tripunctata (Müller) Bory. Redundancy analysis (RDA) was used to detect the relationships between diatoms, some environmental factors and sampling sites. Diatoms of the epiphytic community showed a clearly grouping in relation to the sampling sites as compared with diatoms of the epilithic community. Species common to both communities showed a similar correlation with some environmental variables (BOD, pH, NH₄⁺, TP, NO₃^? and conductivity), with three exceptions (Diatoma vulgaris, Cymbella compacta, and Encyonema silesiacum). Pearson’s correlation coefficient showed correlation between selected environmental variables and diatom indices calculated using OMNIDIA 6.2 software (TDI, IPS, CEE, GENRE, TID, SID, SHE and IDSE/5). Diatoms of the epiphytic community are more clearly clustered in relation to the sampling sites as compared with diatoms of the epilithic community. According to our results there is still “place” in biomonitoring for epiphytic community. The present study highlights the necessity of sampling both epiphytic and epilithic communities because substrate specificity could play important role in biomonitoring.     

Revision of the carabid genus <Emphasis Type="Italic">Meroctenus</Emphasis> Gemminger et Harold,with a new status of <Emphasis Type="Italic">Xenodochus</Emphasis> Andrewes (Coleoptera,Carabidae: Harpalini)

Originally described as a monotypical genus with unclear taxonomic position from Sudan, Meroctenus Gemminger et Harold, 1868 is treated as a polytypical genus of the Selenophori genus group with two subgenera: Meroctenus s. str. and Xenodochus Andrewes, 1941, stat. n. (the latter was previously considered a distinct genus). Within Meroctenus, two species are recognized: M. (Meroctenus) crenulatus Chaudoir, 1843 (type species) and M. (M.) mediocris (Andrewes, 1936), comb, n., transferred to Meroctenus s. str. from Xenodochus. A new subspecies M. (M.) crenulatus orientalis subsp. n. is described from Pakistan. Diagnoses of the genus Meroctenus in new interpretation as well as of its two subgenera are discussed, and a taxonomic review of the subgenus Meroctenus s. str. with a key to the species and subspecies is provided. The following synonymy is proposed: Meroctenus Gemminger et Harold, 1868 = Paregaploa Müller, 1947, syn. n.; Meroctenus crenulatus (Chaudoir, 1843) = Egaploa (Paregaploa) conviva Müller, 1947, syn. n. Lectotypes are designated for Ctenomerus crenulatus Chaudoir, 1843 and Xenodus mediocris Andrewes, 1936.     

Effects of invasive aquatic carrion on soil chemistry and terrestrial microbial communities

Carrion plays a crucial role in the recycling of nutrients and organic matter in ecosystems. Yet, despite their ecological importance, studies addressing the relevance of carrion originated from invasive alien species (IAS) in the interface between aquatic and terrestrial ecosystems are uncommon, especially those assessing belowground effects. In this study, we carried out a manipulative experiment to assess the impact of massive mortalities of the Asian clam Corbicula fluminea (Müller, 1774) as a carrion subsidy evaluating possible effects on the terrestrial soil chemistry and the structure of a microbial (bacteria and fungi) community. We placed five levels of C. fluminea density (0, 100, 500, 1000 and 2000 ind. m^?2) and samples were collected 7, 30 and 90 days after clams’ addition. The results revealed that C. fluminea carrion have a significant effect belowground, especially on nutrients content (mainly NH₄ ⁺, NO₂ ^?, NO₃ ^? and PO₄ ^3?), fungal biomass and fungal and bacterial diversity. Given the predicted increase and intensification of extreme climatic events and the widespread distribution of several aquatic IAS (including bivalve species such as C. fluminea) the ecological importance of these massive mortalities (and resulting carrion) cannot be ignored because they may affect microbial communities with significant impacts on nutrient cycling, even in adjacent terrestrial habitats.     

N<Subscript>2</Subscript>O and CH<Subscript>4</Subscript> emission from <Emphasis Type="Italic">Miscanthus</Emphasis> energy crop fields in the infertile Loess Plateau of China

Background

The greenhouse gas (GHG) mitigation is one of the most important environmental benefits of using bioenergy replacing fossil fuels. Nitrous oxide (N₂O) and methane (CH₄) are important GHGs and have drawn extra attention for their roles in global warming. Although there have been many works of soil emissions of N₂O and CH₄ from bioenergy crops in the field scale, GHG emissions in large area of marginal lands are rather sparse and how soil temperature and moisture affect the emission potential remains unknown. Therefore, we sought to estimate the regional GHG emission based on N₂O and CH₄ releases from the energy crop fields.

Results

Here we sampled the top soils from two Miscanthus fields and incubated them using a short-term laboratory microcosm approach under different conditions of typical soil temperatures and moistures. Based on the emission measurements of N₂O and CH₄, we developed a model to estimate annual regional GHG emission of Miscanthus production in the infertile Loess Plateau of China. The results showed that the N₂O emission potential was 0.27 kg N ha^?1 year^?1 and clearly lower than that of croplands and grasslands. The CH₄ uptake potential was 1.06 kg C ha^?1 year^?1 and was slightly higher than that of croplands. Integrated with our previous study on the emission of CO₂, the net greenhouse effect of three major GHGs (N₂O, CH₄ and CO₂) from Miscanthus fields was 4.08 t CO_2eq ha^?1 year^?1 in the Loess Plateau, which was lower than that of croplands, grasslands and shrub lands.

Conclusions

Our study revealed that Miscanthus production may hold a great potential for GHG mitigation in the vast infertile land in the Loess Plateau of China and could contribute to the sustainable energy utilization and have positive environmental impact on the region.

     

<Emphasis Type="Italic">Nibribacter flagellatus</Emphasis> sp. nov., isolated from rhizosphere of <Emphasis Type="Italic">Hibiscus syriacus</Emphasis> and emended description of the genus <Emphasis Type="Italic">Nibribacter</Emphasis>

A Gram-stain negative, aerobic, motile by flagella, rod-shaped strain (THG-T16^T) was isolated from rhizosphere of Hibiscus syriacus. Growth occurred at 10–40 °C (optimum 28–30 °C), at pH 6.0–8.0 (optimum 7.0) and at 0–1.0% NaCl (optimum 0%). Based on 16S rRNA gene sequence analysis, the near phylogenetic neighbours of strain THG-T16^T were identified as Nibribacter koreensis KACC 16450^T (98.6%), Rufibacter roseus KCTC 42217^T (94.7%), Rufibacter immobilis CCTCC AB 2013351^T (94.5%) and Rufibacter tibetensis CCTCC AB 208084^T (94.4%). The DNA G+C content of strain THG-T16^T was determined to be 46.7 mol%. DNA–DNA hybridization values between strain THG-T16^T and N. koreensis KACC 16450^T, R. roseus KCTC 42217^T, R. immobilis CCTCC AB 2013351^T, R.tibetensis CCTCC AB 208084^T were 33.5?±?0.5% (31.7?±?0.7% reciprocal analysis), 28.1?±?0.2% (25.2?±?0.2%), 17.1?±?0.9% (10.2?±?0.6%) and 8.1?±?0.3% (5.2?±?0.1%). The polar lipids were identified as phosphatidylethanolamine, two unidentified aminophospholipids, an unidentified aminolipid and three unidentified lipids. The quinone was identified as MK-7 and the polyamine as sym-homospermidine. The major fatty acids were identified as C_16:1 ω5c, C_17:1 ω6c, iso-C_15:0, summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c) and summed feature 4 (iso-C_17:1 I and/or anteiso-C_17:1 B). On the basis of the phylogenetic analysis, chemotaxonomic data, physiological characteristics, and DNA–DNA hybridization data, strain THG-T16^T represents a novel species of the genus Nibribacter, for which the name Nibribacter flagellatus sp. nov. is proposed. The type strain is THG-T16^T(=?KACC 19188^T?=?CCTCC AB 2016246^T).     

Nitrate and flooding induce N<Subscript>2</Subscript>O emissions from soybean nodules

Nitrous oxide (N₂O) is one of the three main biogenic greenhouse gases (GHGs) and agriculture represents close to 30 % of the total N₂O net emissions. In agricultural soils, N₂O is emitted by two main microbial processes, nitrification and denitrification, both of which can convert synthetic nitrogen fertilizer into N₂O. Legume-rhizobia symbiosis could be an effective and environmental-friendly alternative to nitrogen fertilization and hence, to mitigate soil N₂O emissions. However, legume crops also contribute to N₂O emissions. A better understanding of the environmental factors involved in the emission of N₂O from nodules would be instrumental for mitigating the release of this GHG gas. In this work, in vivo N₂O emissions from nodulated soybean roots in response to nitrate (0, 1, 2 and 4 mM) and flooding have been measured. To investigate the contribution of rhizobial denitrification in N₂O emission from nodules, plants were inoculated with B. japonicum USDA110 and napA and nosZ denitrification mutants. The results showed that nitrate was essential for N₂O emissions and its concentration enhanced N₂O fluxes showing a statistical linear correlation, being the highest N₂O fluxes obtained with 4 mM nitrate. When inoculated plants grown with 4 mM nitrate were subjected to flooding, a 150- and 830-fold induction of N₂O emission rates from USDA110 and nosZ nodulated roots, respectively, was observed compared to non-flooded plants, especially during long-term flooding. Under these conditions, N₂O emissions from detached nodules produced by the napA mutant were significantly lower (p?<?0.05) than those produced by the wild-type strain (382 versus 1120 nmol N₂O h^?1 g^?1 NFW, respectively). In contrast, nodules from plants inoculated with the nosZ mutant accumulated statistically higher levels of N₂O compared to wild-type nodules (2522 versus nmol 1120 N₂O h^?1 g^?1 NFW, p?<?0.05). These results demonstrate that flooding is an important environmental factor for N₂O emissions from soybean nodules and that B. japonicum denitrification is involved in such emission.     

Identification of Ca<Superscript>2+</Superscript> signaling components in neural stem/progenitor cells during differentiation into neurons and glia in intact and dissociated zebrafish neurospheres

The development of the CNS in vertebrate embryos involves the generation of different sub-types of neurons and glia in a complex but highly-ordered spatio-temporal manner. Zebrafish are commonly used for exploring the development, plasticity and regeneration of the CNS, and the recent development of reliable protocols for isolating and culturing neural stem/progenitor cells (NSCs/NPCs) from the brain of adult fish now enables the exploration of mechanisms underlying the induction/specification/differentiation of these cells. Here, we refined a protocol to generate proliferating and differentiating neurospheres from the entire brain of adult zebrafish. We demonstrated via RT-qPCR that some isoforms of ip3r, ryr and stim are upregulated/downregulated significantly in differentiating neurospheres, and via immunolabelling that 1,4,5-inositol trisphosphate receptor (IP₃R) type-1 and ryanodine receptor (RyR) type-2 are differentially expressed in cells with neuron- or radial glial-like properties. Furthermore, ATP but not caffeine (IP₃R and RyR agonists, respectively), induced the generation of Ca²⁺ transients in cells exhibiting neuron- or glial-like morphology. These results indicate the differential expression of components of the Ca²⁺-signaling toolkit in proliferating and differentiating cells. Thus, given the complexity of the intact vertebrate brain, neurospheres might be a useful system for exploring neurodegenerative disease diagnosis protocols and drug development using Ca²⁺ signaling as a read-out.     

Changes in growth and composition of the marine microalgae <Emphasis Type="Italic">Phaeodactylum tricornutum</Emphasis> and <Emphasis Type="Italic">Nannochloropsis salina</Emphasis> in response to changing sodium bicarbonate concentrations

Oils, carbohydrates, and fats generated by microalgae are being refined in an effort to produce biofuels. The research presented here examines two marine microalgae, Nannochloropsis salina (green alga) and Phaeodactylum tricornutum (diatom), when grown with 0 (no addition), 0.5, 1.0, 2.0, and 5.0 g L^?1 NaHCO₃ added to an f/2 medium during the growth phase (GP) and a nutrient induced (nitrate limitation) lipid formation phase (LP). We hypothesize that the addition of NaHCO₃ is a sustainable and practical strategy to increase cellular density and concentrations of lipids in microalgae as well as the rate of lipid accumulation. In N. salina, final cell densities were significantly (p?<?0.05) higher in the NaHCO₃-treated cells than the control while in P. tricornutum the cell densities were higher with >[NaHCO₃] during the GP. During the LP, cell densities were generally higher in the NaHCO₃-treated cells compared with controls. F _V/F _M (efficiency of photosystem II) patterns paralleled those for cell density with generally higher values with higher concentrations of NaHCO₃ and significantly different values between controls and 5.0 g L^?1 NaHCO₃ at the end of the GP (p?<?0.05). F _V/F _M was variable between treatments in P. tricornutum (0.3–0.65) but less so in N. salina for (0.5–0.7) regardless of [NaHCO₃]. The lipid index (measured with Nile red), used as a proxy for triacylglycerides (TAGs), was 10.2?±?6.5 and 4.4?±?2.9 (fluorescence units/OD cells ×1000) for N. salina and P. tricornutum, respectively, at the end of the GP. At the end of the LP, the lipid index was eight and four times higher than during the GP in the corresponding 5.0 g L^?1 NaHCO₃ treatments, revealing that N. salina was accumulating more lipid than P. tricornutum. Dry weights essentially doubled during LP compared with GP for N. salina; this was not the case for P. tricornutum. In general, the percentage of ash in dry weights was significantly higher in the LP relative to the corresponding GP treatments for P. tricornutum; this was not the case for N. salina. During the LP, there was also less soluble protein in N. salina compared to GP; differences were not significant in cells growing with 2.0 or 5.0 g L^?1 NaHCO₃. In P. tricornutum, faster growing cells had more soluble protein during the GP and LP; differences between treatments were significant. P. tricornutum generally accumulated significantly more crude protein than N. salina at higher [NaHCO₃]; there was three times more crude protein in the highest NaHCO₃ (5.0 g L^?1) treatment compared with the controls. C:N ratios (mol:mol) were similar across treatments during GP: 7.03?±?0.12 and 10.16?±?0.41 for N. salina and P. tricornutum, respectively. Further, C:N ratios increased with increasing [NaHCO₃] during LP. Species-specific fatty acid methyl ester (FAMEs) profiles were observed. While C16:0 was lower in P. tricornutum compared to N. salina, the diatom produced more C16:1 and C14 but not C18:3. Monounsaturated fatty acids (MUFA) significantly increased in N. salina in the LP compared to GP and in response to increasing [NaHCO₃] (t tests; p?<?0.05). Saturated fatty acids (SFA) responded similarly but to a lesser degree. There were more polyunsaturated fatty acids (PUFA) in N. salina than MUFAs or SFAs. In P. tricornutum, there were generally more SFAs, MUFAs and PUFAs in P. tricornutum during LP than GP in the corresponding NaHCO₃ treatments. These findings reveal the importance of considering NaHCO₃ as a supplemental carbon source in the culturing marine phytoplankton in large-scale production for biofuels.     

Resveratrol Inhibits Diabetic-Induced Müller Cells Apoptosis through MicroRNA-29b/Specificity Protein 1 Pathway

The aim of this study was to evaluate the anti-apoptosis effects of resveratrol (RSV) on diabetic rats retinal Müller cells in vivo and in vitro and to further investigate the roles of microRNA-29b (miR-29b)/specificity protein 1 (SP1) in the anti-apoptosis mechanism of RSV. Retina was obtained from normal and diabetic rats with or without RSV (5 and 10 mg/kg/day) treatments at 1–7 months. TdT-mediated dUTP-biotin nick end labeling (TUNEL) and Annexin V/PI staining were used to detect apoptosis. Immunofluorescence was used to assess distribution of SP1 in retina. MiR-29b and SP1 messenger RNA (mRNA) expression was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). SP1, Bax, and bcl-2 protein expression was evaluated by western blotting. Caspase-3 activity was detected by assay kit. Our study showed that the TUNEL-positive cells were mainly localized in the inner nuclear layer (INL) of retina and RSV administration effectively suppressed streptozotocin (STZ)-induced apoptosis of retinal cells in INL in vivo (P?<?0.001). Our study also showed that RSV administration effectively suppressed high glucose (HG)-induced retinal Müller cells’ apoptosis in vitro (P?<?0.001). Furthermore, our study revealed that the diabetes-induced downregulated expression of miR-29b and upregulated expression of SP1 could be rescued by RSV in vivo and in vitro (P?<?0.05). The anti-apoptosis effect and downregulated SP1 expression effect of RSV was prevented by miR-29b inhibitor (P?<?0.05). MiR-29b mimic increased the above-mentioned effects of RSV (P?<?0.001). These findings indicate that RSV is a potential therapeutic option for diabetic retinopathy (DR) and that miR-29b/SP1 pathway play roles in the anti-apoptosis mechanism of RSV.     

Natively oxidized amino acid residues in the spinach cytochrome <Emphasis Type="Italic">b</Emphasis><Subscript><Emphasis Type="Italic">6</Emphasis></Subscript><Emphasis Type="Italic">f</Emphasis> complex

The cytochrome b ₆ f complex of oxygenic photosynthesis produces substantial levels of reactive oxygen species (ROS). It has been observed that the ROS production rate by b ₆ f is 10–20 fold higher than that observed for the analogous respiratory cytochrome bc₁ complex. The types of ROS produced (O₂^{??, 1}O₂, and, possibly, H₂O₂) and the site(s) of ROS production within the b ₆ f complex have been the subject of some debate. Proposed sources of ROS have included the heme b _p , PQ _p ^?? (possible sources for O₂^??), the Rieske iron–sulfur cluster (possible source of O₂^?? and/or ¹O₂), Chl a (possible source of ¹O₂), and heme c _n (possible source of O₂^?? and/or H₂O₂). Our working hypothesis is that amino acid residues proximal to the ROS production sites will be more susceptible to oxidative modification than distant residues. In the current study, we have identified natively oxidized amino acid residues in the subunits of the spinach cytochrome b ₆ f complex. The oxidized residues were identified by tandem mass spectrometry using the MassMatrix Program. Our results indicate that numerous residues, principally localized near p-side cofactors and Chl a, were oxidatively modified. We hypothesize that these sites are sources for ROS generation in the spinach cytochrome b ₆ f complex.     

Quorum sensing systems of regulation,synthesis of phenazine antibiotics,and antifungal activity in rhizospheric bacterium <Emphasis Type="Italic">pseudomonas chlororaphis</Emphasis> 449

Strain Pseudomonas chlororaphis 449, an antagonist of a broad spectrum of phytopathogenic microorganisms isolated from the maize rhizosphere, was shown to produce three phenazine antibiotics: phenazine-1-carboxylic acid (PCA), 2-hydroxylphenazine-1-carboxylic acid (2-OH-PCA), and 2-hydroxylphenazine (2-OH-PHZ). Two Quorum Sensing (QS) systems of regulation were identified: Phz/R and CsaI/R. Genes phzI and csaI were cloned and sequenced. Cells of strain 449 synthesize at least three types of AHL: N-butanoyl-L-homoserine lactone (C₄-AHL), N-hexanoyl-L-homoserine lactone (C₆-AHL), and N-(3-oxo-hexanoyl)-L-homoserine lactone (30C₆-AHL). Transposon mutagenesis was used to generate mutants of strain 449 deficient in synthesis of phenazines, which carried inactivated phzA and phzB genes of the phenazine operon and gene phzO. Mutations phzA ^? and phzB ^? caused a drastic reduction in the antagonistic activity of bacteria toward phytopathogenic fungi. Both mutants lost the ability to protect cucumber and leguminous plants against phytopathogenic fungi Rhizoctonia solani and Sclerotinia sclerotiorum. These results suggest a significant role of phenazines in the antagonistic activity of P. chlororaphis 449.     

Protective Effects of <Emphasis Type="Italic">Mekabu</Emphasis> Aqueous Solution Fermented by <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> Sanriku-SU7 on Human Enterocyte-Like HT-29-luc Cells and DSS-Induced Murine IBD Model

Most wakame Undaria pinnatifida, a brown algae, products are made from the frond portion. In this study, the polysaccharide content and antioxidant property of aqueous extract solutions (AESs) of the four parts (frond: wakame, stem of the frond: kuki-wakame, sporophyll: mekabu, and kuki-mekabu) of wakame were investigated. Polysaccharide content was high in both the wakame and mekabu. Superoxide anion (O₂ ^?) radical-scavenging capacities were high in the mekabu. These AESs could be fermented by Lactobacillus plantarum Sanriku-SU7. The O₂ ^? radical-scavenging activity of the kuki-wakame, mekabu, and kuki-mekabu were increased by the fermentation. Fermented mekabu clearly showed a protective effect on human enterocyte-like HT-29-luc cells and in a mouse model of dextran sodium sulphate-induced inflammatory bowel disease (IBD). These results suggest that the mekabu fermented by L. plantarum Sanriku-SU7 has anti-IBD effect related to O₂ ^? radical-scavenging.     

Growth and photosynthetic response of two larches exposed to O<Subscript>3</Subscript> mixing ratios ranging from preindustrial to near future

In this study, we questioned whether ground-level ozone (O₃) induces hormesis in Japanese larch (Larix kaempferi) and its hybrid F₁ (L. gmelinii var. japonica × L. kaempferi). In order to answer the question, we exposed seedlings of both taxa to four O₃ treatments [ranging from ≈10 to 60 nmol(O₃) mol^–1] in open-top chambers for two consecutive growing seasons. We found a hormetic response in maximum photosynthetic rate (P_Nmax) at 1700 μmol(CO₂) mol^–1 and maximum rates of carboxylation (V_cmax) and electron transport (J_max) in both larches. Stimulation of P_Nmax, V_cmax, and J_max did not lead to suppressed plant productivity in Japanese larch, which followed a stress-tolerant strategy, but it did lead to suppressed plant productivity in hybrid larch which followed a competitive strategy. These findings are the first to suggest that stimulation of physiological functions by low O₃ exposures may have negative consequences for larch reproduction.