Atomic Layer Deposition of Zirconia on Titanium Implants Improves Osseointegration in Rabbit Bones.

Purpose: Atomic layer deposition (ALD) is a method that can deposit zirconia uniformly on an atomic basis. The effect of deposited zirconia on titanium implants using ALD was evaluated in vivo. Methods: Machined titanium implants (MTIs) were used as the Control. MTIs treated by sandblasting with large grit and acid etching (SA) and MTIs deposited with zirconia using ALD are referred to as Groups S and Z, respectively. Twelve implants were prepared for each group. Six rabbits were used as experimental animals. To evaluate the osteogenesis and osteocyte aspects around the implants, radiological and histological analyses were performed. The bone-to-implant contact (BIC) ratio was measured and statistically analyzed to evaluate the osseointegration capabilities. Results: In the micro-CT analysis, more radiopaque bone tissues were observed around the implants in Groups S and Z. Histological observation found that Groups S and Z had more and denser mature bone tissues around the implants in the cortical bone area. Many new and mature bone tissues were also observed in the medullary cavity area. For the BIC ratio, Groups S and Z were significantly higher than the Control in the cortical bone area (P < 0.017), but there was no significant difference between Groups S and Z. Conclusion: MTIs deposited with zirconia using ALD (Group Z) radiologically and histologically showed more mature bone formation and activated osteocytes compared with MTIs (Control). Group Z also had a significantly higher BIC ratio than the Control. Within the limitations of this study, depositing zirconia on the surface of MTIs using ALD can improve osseointegration in vivo.

Biological and Chemical Approaches for Controlling Harmful Microcystis Blooms.

The proliferation of harmful cyanobacterial blooms dominated by Microcystis aeruginosa has become an increasingly serious problem in freshwater ecosystems due to climate change and eutrophication. Microcystis-blooms in freshwater generate compounds with unpleasant odors, reduce the levels of dissolved O2, and excrete microcystins into aquatic ecosystems, potentially harming various organisms, including humans. Various chemical and biological approaches have thus been developed to mitigate the impact of the blooms, though issues such as secondary pollution and high economic costs have not been adequately addressed. Red clays and H2O2 are conventional treatment methods that have been employed worldwide for the mitigation of the blooms, while novel approaches, such as the use of plant or microbial metabolites and antagonistic bacteria, have also recently been proposed. Many of these methods rely on the generation of reactive oxygen species, the inhibition of photosynthesis, and/or the disruption of cellular membranes as their mechanisms of action, which may also negatively impact other freshwater microbiota. Nevertheless, the underlying molecular mechanisms of anticyanobacterial chemicals and antagonistic bacteria remain unclear. This review thus discusses both conventional and innovative approaches for the management of M. aeruginosa in freshwater bodies.

Kaistella rhinocerotis sp. nov., isolated from the faeces of rhinoceros and reclassification of Chryseobacterium faecale as Kaistella faecalis comb. nov.

Strain Ran72T, a novel Gram-stain-negative, obligately aerobic, non-motile, and rod-shaped bacterium, was isolated from the faeces of the rhinoceros species Ceratotherium simum. The novel bacterial strain grew optimally in Reasoner's 2A medium under the following conditions: 0 % (w/v) NaCl, pH 7.5, and 30 °C. Based on phylogenetic analysis using 16S rRNA gene sequencing, strain Ran72T was found to be most closely related to Chryseobacterium faecale F4T (98.4 %), Kaistella soli DKR-2T (98.0 %), and Kaistella haifensis H38T (97.4 %). A comprehensive genome-level comparison between strain Ran72T with C. faecale F4T, K. soli DKR-2T, and K. haifensis H38T revealed average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity values of ≤74.9, ≤19.3, and ≤78.7 %, respectively. The major fatty acids were anteiso-C15 : 0 (22.3 %), with MK-6 being the predominant respiratory quinone. The major polar lipids of strain Ran72T were phosphatidylethanolamine, four unidentified aminolipids, and two unidentified lipids. Based on our chemotaxonomic, genotypic, and phenotype characterizations, strain Ran72T was identified as representing a novel species in the genus Kaistella, for which the name Kaistella rhinocerotis sp. nov. is proposed, with the type strain Ran72T (=KACC 23136T=JCM 36038T). Based on the outcomes of our phylogenomic study, Chryseobacterium faecale should be reclassified under the genus Kaistella as Kaistella faecalis comb. nov.

Sustainable control of Microcystis aeruginosa, a harmful cyanobacterium, using Selaginella tamariscina extracts.

Eco-friendly reagents derived from plants represent a promising strategy to mitigate the occurrence of toxic cyanobacterial blooms. The use of an amentoflavone-containing Selaginella tamariscina extract (STE) markedly decreased the number of Microcystis aeruginosa cells, thus demonstrating significant anti-cyanobacterial activity. In particular, the Microcystis-killing fraction obtained from pulverized S. tamariscina using hot-water-based extraction at temperatures of 40 °C induced cell disruption in both axenic and xenic M. aeruginosa. Liquid chromatographic analysis was also conducted to measure the concentration of amentoflavone in the STE, thus supporting the potential M. aeruginosa-specific killing effects of STE. Bacterial community analysis revealed that STE treatment led to a reduction in the relative abundance of Microcystis species while also increasing the 16S rRNA gene copy number in both xenic M. aeruginosa NIBR18 and cyanobacterial bloom samples isolated from a freshwater environment. Subsequent testing on bacteria, cyanobacteria, and algae isolated from freshwater revealed that STE was not toxic for other taxa. Furthermore, ecotoxicology assessment involving Aliivibrio fischeri, Daphnia magna, and Danio rerio found that high STE doses immobilized D. magna but did not impact the other organisms, while there was no change in the water quality. Overall, due to its effective Microcystis-killing capability and low ecotoxicity, aqueous STE represents a promising practical alternative for the management of Microcystis blooms.

Lineage-specific evolution of Aquibium, a close relative of Mesorhizobium, during habitat adaptation.

The novel genus Aquibium that lacks nitrogenase was recently reclassified from the Mesorhizobium genus. The genomes of Aquibium species isolated from water were smaller and had higher GC contents than those of Mesorhizobium species. Six Mesorhizobium species lacking nitrogenase were found to exhibit low similarity in the average nucleotide identity values to the other 24 Mesorhizobium species. Therefore, they were classified as the non-N2-fixing Mesorhizobium lineage (N-ML), an evolutionary intermediate species. The results of our phylogenomic analyses and the loss of Rhizobiales-specific fur/mur indicated that Mesorhizobium species may have evolved from Aquibium species through an ecological transition. Halotolerant and alkali-resistant Aquibium and Mesorhizobium microcysteis belonging to N-ML possessed many tripartite ATP-independent periplasmic transporter and sodium/proton antiporter subunits composed of seven genes (mrpABCDEFG). These genes were not present in the N2-fixing Mesorhizobium lineage (ML), suggesting that genes acquired for adaptation to highly saline and alkaline environments were lost during the evolution of ML as the habitat changed to soil. Land-to-water habitat changes in Aquibium species, close relatives of Mesorhizobium species, could have influenced their genomic evolution by the gain and loss of genes. Our study indicated that lineage-specific evolution could have played a significant role in shaping their genome architecture and conferring their ability to thrive in different habitats.IMPORTANCEPhylogenetic analyses revealed that the Aquibium lineage (AL) and non-N2-fixing Mesorhizobium lineage (N-ML) were monophyletically grouped into distinct clusters separate from the N2-fixing Mesorhizobium lineage (ML). The N-ML, an evolutionary intermediate species having characteristics of both ancestral and descendant species, could provide a genomic snapshot of the genetic changes that occur during adaptation. Genomic analyses of AL, N-ML, and ML revealed that changes in the levels of genes related to transporters, chemotaxis, and nitrogen fixation likely reflect adaptations to different environmental conditions. Our study sheds light on the complex and dynamic nature of the evolution of rhizobia in response to changes in their environment and highlights the crucial role of genomic analysis in understanding these processes.

Effects of TiO2 Nanotubes and Reduced Graphene Oxide on Streptococcus mutans and Preosteoblastic Cells at an Early Stage.

The effects of TiO2 nanotube (TNT) and reduced graphene oxide (rGO) deposition onto titanium, which is widely used in dental implants, on Streptococcus mutans (S. mutans) and preosteoblastic cells were evaluated. TNTs were formed through anodic oxidation on pure titanium, and rGO was deposited using an atmospheric plasma generator. The specimens used were divided into a control group of titanium specimens and three experimental groups: Group N (specimens with TNT formation), Group G (rGO-deposited specimens), and Group NG (specimens under rGO deposition after TNT formation). Adhesion of S. mutans to the surface was assessed after 24 h of culture using a crystal violet assay, while adhesion and proliferation of MC3T3-E1 cells, a mouse preosteoblastic cell line, were evaluated after 24 and 72 h through a water-soluble tetrazolium salt assay. TNT formation and rGO deposition on titanium decreased S. mutans adhesion (p < 0.05) and increased MC3T3-E1 cell adhesion and proliferation (p < 0.0083). In Group NG, S. mutans adhesion was the lowest (p < 0.05), while MC3T3-E1 cell proliferation was the highest (p < 0.0083). In this study, TNT formation and rGO deposition on a pure titanium surface inhibited the adhesion of S. mutans at an early stage and increased the initial adhesion and proliferation of preosteoblastic cells.

Antagonistic actions of Paucibacter aquatile B51 and its lasso peptide paucinodin toward cyanobacterial bloom-forming Microcystis aeruginosa PCC7806.

Superior antagonistic activity against axenic Microcystis aeruginosa PCC7806 was observed with Paucibacter sp. B51 isolated from cyanobacterial bloom samples among 43 tested freshwater bacterial species. Complete genome sequencing, analyzing average nucleotide identity and digital DNA-DNA hybridization, designated the B51 strain as Paucibacter aquatile. Electron and fluorescence microscopic image analyses revealed the presence of the B51 strain in the vicinity of M. aeruginosa cells, which might provoke direct inhibition of the photosynthetic activity of the PCC7806 cells, leading to perturbation of cellular metabolisms and consequent cell death. Our speculation was supported by the findings that growth failure of the PCC7806 cells led to low pH conditions with fewer chlorophylls and down-regulation of photosystem genes (e.g., psbD and psaB) during their 48-h co-culture condition. Interestingly, the concentrated ethyl acetate extracts obtained from B51-grown supernatant exhibited a growth-inhibitory effect on PCC7806. The physical separation of both strains by a filter system led to no inhibitory activity of the B51 cells, suggesting that contact-mediated anti-cyanobacterial compounds might also be responsible for hampering the growth of the PCC7806 cells. Bioinformatic tools identified 12 gene clusters that possibly produce secondary metabolites, including a class II lasso peptide in the B51 genome. Further chemical analysis demonstrated anti-cyanobacterial activity from fractionated samples having a rubrivinodin-like lasso peptide, named paucinodin. Taken together, both contact-mediated inhibition of photosynthesis and the lasso peptide secretion of the B51 strain are responsible for the anti-cyanobacterial activity of P. aquatile B51.

The ß-Lactamase Activity at the Community Level Confers ß-Lactam Resistance to Bloom-Forming Microcystis aeruginosa Cells.

Many freshwater cyanobacteria, including Microcystis aeruginosa, lack several known antibiotic resistance genes; however, both axenic and xenic M. aeruginosa strains exhibited high antibiotic resistance against many antibiotics under our tested concentrations, including colistin, trimethoprim, and kanamycin. Interestingly, axenic PCC7806, although not the xenic NIBR18 and NIBR452 strains, displayed susceptibility to ampicillin and amoxicillin, indicating that the associated bacteria in the phycosphere could confer such antibiotic resistance to xenic strains. Fluorescence and scanning electron microscopic observations revealed their tight association, leading to possible community-level ß-lactamase activity. Combinatory treatment of ampicillin with a ß-lactamase inhibitor, sulbactam, abolished the ampicillin resistance in the xenic stains. The nitrocefin-based assay confirmed the presence of significant community-level ß-lactamase activity. Our tested low ampicillin concentration and high ß-lactamase activity could potentially balance the competitive advantage of these dominant species and provide opportunities for the less competitive species, thereby resulting in higher bacterial diversity under ampicillin treatment conditions. Non-PCR-based metagenome data from xenic NIBR18 cultures revealed the dominance of blaOXA-related antibiotic resistance genes followed by other class A ß-lactamase genes (AST-1 and FAR-1). Alleviation of ampicillin toxicity could be observed only in axenic PCC7806, which had been cocultured with ß-lactamase from other freshwater bacteria. Our study suggested M. aeruginosa develops resistance to old-class ß-lactam antibiotics through altruism, where associated bacteria protect axenic M. aeruginosa cells.

Unlocking the mystery of lysine toxicity on Microcystis aeruginosa.

Lysine toxicity on certain groups of bacterial cells has been recognized for many years, but the detailed molecular mechanisms that drive this phenomenon have not been elucidated. Many cyanobacteria including Microcystis aeruginosa cannot efficiently export and degrade lysine, although they have evolved to maintain a single copy of the lysine uptake system through which arginine or ornithine can also be transported into the cytoplasm. Autoradiographic analysis using 14C-l-lysine confirmed that lysine was competitively uptaken into cells with arginine or ornithine, which explained the arginine or ornithine-mediated alleviation of lysine toxicity in M. aeruginosa. A relatively non-specific MurE amino acid ligase could incorporate l-lysine into the 3rd position of UDP-N-acetylmuramyl-tripeptide by replacing meso-diaminopimelic acid during the stepwise addition of amino acids on peptidoglycan (PG) biosynthesis. However, further transpeptidation was blocked because lysine substitution at the pentapeptide of the cell wall inhibited the activity of transpeptidases. The leaky PG structure caused irreversible damage to the photosynthetic system and membrane integrity. Collectively, our results suggest that a lysine-mediated coarse-grained PG network and the absence of concrete septal PG lead to the death of slow-growing cyanobacteria.

6-Bromo-2-naphthol from Silene armeria extract sensitizes Acinetobacter baumannii strains to polymyxin.

The overuse of antibiotics has led to the emergence of multidrug-resistant bacteria, which are resistant to various antibiotics. Combination therapies using natural compounds with antibiotics have been found to have synergistic effects against several pathogens. Synergistic natural compounds can potentiate the effects of polymyxins for the treatment of Acinetobacter baumannii infection. Out of 120 types of plant extracts, only Silene armeria extract (SAE) showed a synergistic effect with polymyxin B (PMB) in our fractional inhibitory concentration and time-kill analyses. The survival rate of G. mellonella infected with A. baumannii ATCC 17978 increased following the synergistic treatment. Interestingly, the addition of osmolytes, such as trehalose, canceled the synergistic effect of SAE with PMB; however, the underlying mechanism remains unclear. Quadrupole time-of-flight liquid chromatography-mass spectrometry revealed 6-bromo-2-naphthol (6B2N) to be a major active compound that exhibited synergistic effects with PMB. Pretreatment with 6B2N made A. baumannii cells more susceptible to PMB exposure in a time- and concentration-dependent manner, indicating that 6B2N exhibits consequential synergistic action with PMB. Moreover, the exposure of 6B2N-treated cells to PMB led to higher membrane leakage and permeability. The present findings provide a promising approach for utilizing plant extracts as adjuvants to reduce the toxicity of PMB in A. baumannii infection.

Discrete Infomax Codes for Supervised Representation Learning.

For high-dimensional data such as images, learning an encoder that can output a compact yet informative representation is a key task on its own, in addition to facilitating subsequent processing of data. We present a model that produces discrete infomax codes (DIMCO); we train a probabilistic encoder that yields k-way d-dimensional codes associated with input data. Our model maximizes the mutual information between codes and ground-truth class labels, with a regularization which encourages entries of a codeword to be statistically independent. In this context, we show that the infomax principle also justifies existing loss functions, such as cross-entropy as its special cases. Our analysis also shows that using shorter codes reduces overfitting in the context of few-shot classification, and our various experiments show this implicit task-level regularization effect of DIMCO. Furthermore, we show that the codes learned by DIMCO are efficient in terms of both memory and retrieval time compared to prior methods.

Epigallocatechin Gallate Protects against Hypoxia-Induced Inflammation in Microglia via NF-κB Suppression and Nrf-2/HO-1 Activation.

Hypoxia-induced neuroinflammation in stroke, neonatal hypoxic encephalopathy, and other diseases subsequently contributes to neurological damage and neuronal diseases. Microglia are the primary neuroimmune cells that play a crucial role in cerebral inflammation. Epigallocatechin gallate (EGCG) has a protective antioxidant and anti-inflammatory effects against neuroinflammation. However, the effects of EGCG on hypoxia-induced inflammation in microglia and the underlying mechanism remain unclear. In this study, we investigated whether EGCG might have a protective effect against hypoxia injury in microglia by treatment with CoCl2 to establish a hypoxic model of BV2 microglia cells following EGCG pre-treatment. An exposure of cells to CoCl2 caused an increase in inflammatory mediator interleukin (IL)-6, inducible nitric oxide synthase (iNOS), and cyclooxygenase (COX)-2 expression, which were significantly ameliorated by EGCG via inhibition of NF-κB pathway. In addition, EGCG attenuated the expression of hypoxia-inducible factor (HIF)-1α and the generation of ROS in hypoxic BV2 cells. Furthermore, the suppression of hypoxia-induced IL-6 production by EGCG was mediated via the inhibition of HIF-1α expression and the suppression of ROS generation in BV2 cells. Notably, EGCG increased the Nrf-2 levels and HO-1 levels in the presence of CoCl2. Additionally, EGCG suppressed hypoxia-induced apoptosis of BV2 microglia with cleavage of poly (ADP-ribose) polymerase (PARP) and caspase-3. In summary, EGCG protects microglia from hypoxia-induced inflammation and oxidative stress via abrogating the NF-κB pathway as well as activating the Nrf-2/HO-1 pathway.

Toll-Like Receptor 5 Promotes the Neurogenesis From Embryonic Stem Cells and Adult Hippocampal Neural Stem Cells in Mice.

Toll-like receptors (TLRs) make a crucial contribution to the innate immune response. TLR5 was expressed in embryoid body derived from mouse embryonic stem cells (mESCs) and ßIII-tubulin-positive cells under all-trans retinoic acid-treated condition. TLR5 was upregulated during neural differentiation from mESCs and augmented the neural differentiation of mESCs via nuclear factor-κB and interleukin 6/CREB pathways. Besides, TLR5 was expressed in SOX2- or doublecortin-positive cells in the subgranular zone of the hippocampal dentate gyrus where adult neurogenesis occurs. TLR5 inhibited the proliferation of adult hippocampal neural stem cells (NSCs) by regulating the cell cycle and facilitated the neural differentiation from the adult hippocampal NSCs via JNK pathway. Also, TLR5 deficiency impaired fear memory performance in mice. Our data suggest that TLR5 is a crucial modulator of neurogenesis from mESCs and adult hippocampal NSCs in mice and represents a new therapeutic target in neurological disorders related to cognitive function.

Evaluation of Semen Quality of Jeju Black Cattle (JBC) to Select Bulls Optimal for Breeding and Establish Freezing Conditions Suitable for JBC Sperm.

To optimize the reproduction of Jeju black cattle (JBC), freezing conditions for sperm were established and sperm motility, vitality, morphology, and fertility were evaluated to select the optimal bull for breeding. Semen samples from five JBC bulls were individually mixed with freezing medium at a final concentration of 1 × 108 sperm/mL and frozen in liquid nitrogen vapor at a height of 3 or 7 cm (referred to as 3 cm sperm and 7 cm sperm, respectively). When the freezing conditions were compared, the motility of 7 cm sperm was significantly higher than that of 3 cm sperm for the JBC-A bull. The motility, curvilinear velocity, straight-line velocity, and average path velocity of fresh and frozen-thawed sperm were the highest for the JBC-A bull. The vitalities of fresh and frozen-thawed sperm were the highest for the JBC-A/E and JBC-A bulls, respectively. The percentage of normal cells in fresh sperm was the highest for the JBC-D bull. The rates of the normal formation of two pronuclei and total sperm penetration were the highest in zygotes fertilized with sperm from the JBC-A bull. The sperm from the JBC-A bull had superior qualities and are thus the most appropriate choice for the preservation and reproduction of these endangered cattle.

Comprehensive Transcriptomic Analysis of Cordyceps militaris Cultivated on Germinated Soybeans.

The ascomycete fungus Cordyceps militaris infects lepidopteran larvae and pupae and forms characteristic fruiting bodies. Owing to its immune-enhancing effects, the fungus has been used as a medicine. For industrial application, this fungus can be grown on geminated soybeans as an alternative protein source. In our study, we performed a comprehensive transcriptomic analysis to identify core gene sets during C. militaris cultivation on germinated soybeans. RNA-Seq technology was applied to the fungal cultures at seven-time points (2, 4, and 7-day and 2, 3, 5, 7-week old cultures) to investigate the global transcriptomic change. We conducted a time-series analysis using a two-step regression strategy and chose 1460 significant genes and assigned them into five clusters. Characterization of each cluster based on Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases revealed that transcription profiles changed after two weeks of incubation. Gene mapping of cordycepin biosynthesis and isoflavone modification pathways also confirmed that gene expression in the early stage of GSC cultivation is important for these metabolic pathways. Our transcriptomic analysis and selected genes provided a comprehensive molecular basis for the cultivation of C. militaris on germinated soybeans.

Aquibium microcysteis gen. nov., sp. nov., isolated from a Microcystis aeruginosa culture and reclassification of Mesorhizobium carbonis as Aquibium carbonis comb. nov. and Mesorhizobium oceanicum as Aquibium oceanicum comb. nov.

A novel bacterial strain, NIBR3T, was isolated from a Microcystis aeruginosa culture. Strain NIBR3T was characterized as Gram-negative, rod-shaped, catalase- and oxidase-positive, and aerobic. The 16S rRNA gene sequence analysis showed that strain NIBR3T was most closely related to Mesorhizobium carbonis B2.3T (=KCTC 52461), Mesorhizobium oceanicum B7T (=KCTC 42783) and Mesorhizobium qingshengii CCBAU 33460T (=HAMBI 3277), at 98.7, 97.2 and 97.2% similarity, respectively. Our phylogenetic analyses revealed that three strains [strain NIBR3T with the previously reported two Mesorhizobium species (M. carbonis B2.3T and M. oceanicum B7T)] formed a distinct cluster from other Mesorhizobium type strains. The average nucleotide identity of strain NIBR3T relative to M. carbonis B2.3T , M. oceanicum B7T, and M. qingshengii CCBAU 33460T was found to be 84.3, 79.4 and 75.8 %, with average amino-acid identities of 85.1, 74.8 and 64.3 %, and digital DNA-DNA hybridization values of 27.6, 22.6 and 20.7 %, respectively. The genome size and genomic DNA G+C content of NIBR3T were 6.1 Mbp and 67.9 mol%, respectively. Growth of strain NIBR3T was observed at 23-45 °C (optimum, 33 °C), at pH 6-11 (optimum, 8) and in the presence of 0-4 % (w/v) NaCl (optimum, 0 %). The major polar lipids in this novel strain were phosphatidylethanolamine, phosphatidylcholine and phosphatidylmethylethanolamine. The predominant respiratory quinone was Q-10. Summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c) was the most abundant cellular fatty acid in strain NIBR3T. Based on genotypic characteristics using our genomic data, strain NIBR3T was identified as a member of new genus, Aquibium gen. nov., with the two aforementioned stains. The type strain f the novel species, Aquibium microcysteis sp. nov., is NIBR3T (=KACC 22092T=HAMBI 3738T). We also reclassified Mesorhizobium carbonis and M. oceanicum as Aquibium carbonis comb. nov. and A. oceanicum comb. nov., respectively.

Roseococcus microcysteis sp. nov., isolated from a Microcystis aeruginosa culture sample.

Strain NIBR12T (=KACC 22094T=HAMBI 3739T), a novel Gram-stain-negative, obligate aerobic, non-spore-forming, non-motile and coccobacillus-shaped bacterium, was isolated from a cyanobacterial sample culture (Microcysitis aeruginosa NIBRCYC000000452). The newly identified bacterial strain grew optimally in modified Reasoner's 2A medium under the following conditions: 0 % (w/v) NaCl, pH 7.5 and 35 °C. Phylogenetic analysis using the 16S rRNA gene sequence confirmed that strain NIBR12T belongs to the genus Roseococcus, with its closest neighbours being Roseococcus suduntuyensis SHETT (98.8%), Roseococcus thiosulfatophilus RB-3T (97.7%), "Sediminicoccus rosea" R-30T (95.7 %) and Rubritepida flocculans H-8T (95.0 %). Genomic comparison of strain NIBR12T with type species in the genus Roseococcus was conducted using digital DNA-DNA hybridization, average nucleotide identity and average amino acid identity analyses, resulting in values of ≤53.7, ≤93.7 and ≤96.1 %, respectively. The genomic DNA G+C content of strain NIBR12T was 70.9 mol%. The major fatty acids of strain NIBR12T were summed feature 8 (C18 : 1 ω7c and/or C18:1 ω6c) and summed feature 3 (C16 : 1 ω6c/C16 : 1 ω7c). Q-9 was its major respiratory quinone. Moreover, the major polar lipids of strain NIBR12T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. Based on our chemotaxonomic, genotypic and phenotype analyses, strain NIBR12T is identified as represeting a novel species of the genus Roseococcus, for which the name Roseococcus microcysteis sp. nov. is proposed.

Linkage between bacterial community-mediated hydrogen peroxide detoxification and the growth of Microcystis aeruginosa.

Microcystis aeruginosa, an important cyanobloom-forming cyanobacterium, is sensitive to the high light intensity and consequent oxidative stress. Based on our genomic and transcriptomic analyses of H2O2-treated cells, many genes involved in photosynthesis, Calvin cycle, and microcystin synthesis were downregulated, whereas several toxin-antitoxin genes, DNA repair genes, and H2O2-defense systems such as peroxiredoxins and glutathione synthesis were upregulated. Axenic M. aeruginosa was then co-cultured with synthetic bacterial communities collected from 15 different freshwater samples with exhibiting different degrees of H2O2-production and catalase activities. Our analyses indicated that H2O2-resistant bacterial communities favored the growth and photosynthetic activity of M. aeruginosa cells under either H2O2 treatment or high light conditions. Nanopore-based bacterial community analyses indicated that these growth-promoting effects were likely attributable to a high proportion of Alphaproteobacteria (e.g., Brevundimonas and Ochrobactrum species), which protected M. aeruginosa cells from H2O2 toxicity. Further, these bacterial communities exhibited higher catalase activity levels and faster O2 production rates upon H2O2 detoxification. Taken together, our findings newly suggest that the occurrence of catalase-less M. aeruginosa blooms is largely influenced by the surrounding microbiota during high light and organic-rich conditions.

Killing effect of deinoxanthins on cyanobloom-forming Microcystis aeruginosa: Eco-friendly production and specific activity of deinoxanthins.

Cyanobacterial blooms caused mainly by Microcystis aeruginosa could be controlled using chemical and biological agents such as H2O2, antagonistic bacteria, and enzymes. Little is known about the possible toxic effects of bacterial membrane pigments on M. aeruginosa cells. Deinococcus metallilatus MA1002 cultured under light increased the production of several carotenoid-like compounds by upregulating two deinoxanthin biosynthesis genes: crtO and cruC. The deinoxanthin compounds were identified using thin-layer chromatography, high-performance liquid chromatography, and liquid chromatography-mass spectrometry. D. metallilatus was cultured with agricultural by-products under light to produce the deinoxanthin compounds. Soybean meal, from six tested agricultural by-products, was selected as the single factor for making an economical medium to produce deinoxanthin compounds. The growth of axenic M. aeruginosa PCC7806, as well as other xenic cyanobacteria such as Cyanobium gracile, Trichormus variabilis, and Dolichospermum circinale, were inhibited by the deinoxanthin compounds. Scanning electron microscopic images showed the complete collapse of M. aeruginosa cells under deinoxanthin treatment, probably due to its interference with cyanobacterial membrane synthesis during cellular elongation. Deinoxanthins appeared to be nontoxic to other non-cyanobacteria such as Acinetobacter, Pseudomonas, Methylobacterium, and Bacillus species, suggesting that it can be a novel candidate for preventing cyanobacterial blooms through its specific activity against cyanobacteria.

The antioxidant icariin protects porcine oocytes from age-related damage in vitro.

OBJECTIVE: If fertilization does not occur within a specific period, the quality of unfertilized oocytes in the oviduct (in vivo aging) or in culture (in vitro aging) will deteriorate over time. Icariin (ICA), found in all species of Epimedium herbs, has strong antioxidant activity, and is thought to exert anti-aging effects in vitro. We asked whether ICA protects oocytes against age-related changes in vitro. METHODS: We analyzed the reactive oxygen species (ROS) levels and expression of antioxidant, maternal, and estrogen receptor genes, and along with spindle morphology, and the developmental competence and quality of embryos in the presence and absence of ICA. RESULTS: Treatment with 5 µM ICA (ICA-5) led to a significant reduction in ROS activity, but increased mRNA expression of glutathione and antioxidant genes (superoxide dismutase 1 [SOD1], SOD2, peroxiredoxin 5, and nuclear factor erythroid 2-like 2), during aging in vitro. In addition, ICA-5 prevented defects in spindle formation and chromosomal alignment, and increased mRNA expression of cytoplasmic maturation factor genes (bone morphogenetic protein 15, cyclin B1, MOS proto-oncogene, serine/threonine kinase, and growth differentiation factor-9). It also prevented apoptosis, increased mRNA expression of antiapoptotic genes (BCL2-like 1 and baculoviral IAP repeat-containing 5), and reduced mRNA expression of pro-apoptotic genes (BCL2 antagonist/killer 1 and activation of caspase-3). Although the maturation and cleavage rates were similar in all groups, the total cell number per blastocyst and the percentage of apoptotic cells at the blastocyst stage were higher and lower, respectively, in the control and ICA-5 groups than in the aging group. CONCLUSION: ICA protects oocytes against damage during aging in vitro; therefore, it can be used to improve assisted reproductive technologies.