[Effects and mechanisms of Gegen Qinlian Decoction in inhibiting M1 polarization of macrophages under inflammatory hypoxia microenvironment].

To explore the effect and mechanism of Gegen Qinlian Decoction(GQD) in inhibiting M1 polarization of macrophages under inflammatory hypoxia by simulating intestinal hypoxia microenvironment in vitro. A tri-gas incubator was used to simulate normal physiological hypoxia of the colon and inflammatory hypoxia microenvironments of ulcerative colitis(UC). RAW264.7 macrophages were divided into 18.5% O_(2 )(normoxia group), 4% O_2(physiological hypoxia group), and 1% O_2(inflammatory hypoxia group), and they were induced by lipopolysaccharide(LPS) for 24 h. M1 polarization was detected by flow cytometry. Under the condition of 1% inflammatory hypoxia, they were divided into blank group, model group, and GQD-containing serum low, medium, and high dose groups. Flow cytometry was used to detect M1 polarization marker CD86, and ELISA was used to detect the expression of tumor necrosis factor-α(TNF-α) and interleukin-1ß(IL-1ß) in cell supernatant. The mRNA expression of hypoxia-inducible factor-1α(HIF-1α), TNF-α, and IL-1ß was detected by qRT-PCR. Western blot was used to detect the expression of HIF-1α/nuclear transcription factor-κB(NF-κB) signaling pathway-related proteins. The nuclear translocation of NF-κB p65 was detected by immunofluorescence. The results showed that the positive rate of CD86 in the 1% O_2 group was the highest. Under the condition of 1% inflammatory hypoxia, compared with the blank group, the expression of CD86, TNF-α, IL-1ß, and HIF-1α in the model group increased. Compared with the model group, each group of GQD could reduce the expression of CD86, TNF-α, IL-1ß, and HIF-1α. Compared with the blank group, the protein expression of HIF-1α, NF-κB p65, p-IKKα/ß, and p-IκBα in the model group increased. Compared with the model group, the protein expression of HIF-1α, NF-κB p65, p-IKKα/ß, and p-IκBα in GQD groups was significantly decreased. Compared with the blank group, NF-κB p65 in the model group entered the nucleus significantly. Compared with the model group, the nuclear expression of NF-κB p65 was decreased in each GQD group. Studies have shown that GQD may protect the intestine by down-regulating the HIF-1α/NF-κB signaling pathway to inhibit M1 polarization of macrophages and secretion of related inflammatory factors under 1% inflammatory hypoxia.

Formononetin Derivative for Osteoporosis by Simultaneous Regulating Osteoblast and Osteoclast.

Seven new formononetin derivatives (1-7) were designed and prepared from formononetin (phase II phytoestrogen). The derivatives 9-butyl-3-(4-methoxyphenyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]oxazin-4-one (2) and 9-(furan-3-ylmethyl)-3-(4-methoxyphenyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]oxazin-4-one (7) promoted significant osteoblast formation by modulating the BMP/Smad pathway. Compound 7 exhibited potent antiosteoclastogenesis activity in RANKL-induced RAW264.7 cells and ovariectomy (OVX)-induced osteoporosis in mice by regulation of the RANK/RANKL/OPG pathway. Compound 7 regulated osteoblast and osteoclast simultaneously and showed better effect than the well-known drug ipriflavone in vivo, suggesting 7 as a patented antiosteoporosis candidate.

Characterization of a novel antioxidant byssal protein from Mytilus coruscus foot.

Mussel byssal proteins are of biomimetic importance for the development of novel underwater bio-adhesive agents. It is important to maintain a reduced state during the process of byssus adhesion. There are 19 mussel foot proteins (MFPs) have been reported in previous studies, among which only MFP-6 had been confirmed as an antioxidant protein in mussel byssus due to the function of cysteines, and playing an essential role in the redox balance of mussel byssus during adhesion process. Although the other four MFPs (MFP-16 ~ MFP-19) also have abundant cysteines, their function is still unknown. In this study, a novel mussel foot protein, named MFP-20, was identified from Mytilus coruscus foot. The sequential features, expression profile, and function of recombinant MFP-20 were verified. The results showed that MFP-20 has more abundant cysteines than other MFPs, the relative expression of mfp-20 was upregulated in Fe3+ stress and low pH seawater. In addition, different adhesive substrates induced significant changes of expression level of mfp-20. Furthermore, rMFP-20 showed strong antioxidant capacity in the DPPH assay, and the abundant cysteines in its sequence may play vital roles in the antioxidation activity. Our findings revealed the possible function of MFP-20 with a totally different sequence from the reported MFP-6 and provided new clues for exploring the redox balance of mussel byssus during the adhesion process.

[Metabolomic study on urine of chronic inflammation rats treated with Buyang Huanwu Decoction based on UPLC-Q-TOF-MS].

The study investigated the effect of Buyang Huanwu Decoction(BYHWD) on endogenous biomarkers in the urine of rats with chronic inflammation induced by lipopolysaccharide(LPS) using ultra-high performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry(UPLC-Q-TOF-MS), aiming to elucidate the molecular mechanism underlying the therapeutic effect of BYHWD on chronic inflammation from a metabolomics perspective. Male SD rats were randomly divided into a normal group, a model group, and low-, medium-, and high-dose BYHWD groups(7.5, 15, and 30 g·kg~(-1)). The model group and BYHWD groups received tail intravenous injection of LPS(200 µg·kg~(-1)) on the first day of each week, followed by oral administration of BYHWD once a day for four consecutive weeks. Urine samples were collected at the end of the administration period, and UPLC-Q-TOF-MS was used to analyze the metabolic profiles of the rat urine in each group. Multivariate statistical analysis methods such as principal component analysis(PCA), partial least squares-discriminant analysis(PLS-DA), and orthogonal partial least squares-discriminant analysis(OPLS-DA) were used to analyze the effect of BYHWD on endogenous metabolites. One-way ANOVA and variable importance for the projection(VIP) were used to screen for potential biomarkers related to chronic inflammation. The identified biomarkers were subjected to pathway and enrichment analysis using MetaboAnalyst 5.0. A total of 25 potential biomarkers were screened and identified in the rat urine in this experiment. Compared with the normal group, the model group showed significant increases in the levels of 14 substances(P<0.05) and significant decreases in the levels of 11 substances(P<0.05). BYHWD was able to effectively reverse the trend of most endogenous biomarkers. Compared with the model group, BYHWD significantly down-regulated 13 biomarkers(P<0.05) and up-regulated 10 biomarkers(P<0.05). The metabolic products were mainly related to the biosynthesis of pantothenic acid and coenzyme A, tryptophan metabolism, retinol metabolism, and propionate metabolism. BYHWD has therapeutic effect on chronic inflammation induced by LPS, which may be related to its ability to improve the levels of endogenous metabolites, enhance the body's anti-inflammatory and antioxidant capabilities, and restore normal metabolic activity.

The growth inhibitory effects and non-targeted metabolomic profiling of Microcystis aeruginosa treated by Scenedesmus sp.

The health of the aquatic ecosystem has recently been severely affected by cyanobacterial blooms brought on by eutrophication. Therefore, it is critical to develop efficient and secure methods to control dangerous cyanobacteria, such as Microcystis aeruginosa. In this research, we tested the inhibition of M. aeruginosa growth by a Scenedesmus sp. strain isolated from a culture pond. Scenedesmus sp. culture filtrate that had been lyophilized was added to M. aeruginosa, and cultivation for seven days, the cell density, chlorophyll a (Chl-a) concentration, maximum quantum yield of photosystem II (Fv/Fm), the activities of superoxide dismutase (SOD), catalase (CAT), and the concentration of malondialdehyde (MDA) and glutathione (GSH) were measured. Moreover, non-targeted metabolomics was carried out to provide light on the inhibitory mechanism in order to better understand the metabolic response. According to the results, M. aeruginosa is effectively inhibited by the lyophilized Scenedesmus sp. culture filtrate at a rate of 51.2%. Additionally, the lyophilized Scenedesmus sp. clearly inhibit the photosystem and damages the antioxidant defense system of M. aeruginosa cells, resulting in oxidative damage, which worsens membrane lipid peroxidation, according to changes in Chl-a, Fv/Fm, SOD, CAT enzyme activities and MDA, GSH. Metabolomics analysis revealed that the secondary metabolites of Scenedesmus sp. significantly interfere with the metabolism of M. aeruginosa involved in amino acid synthesis, membrane creation and oxidative stress, which is coherent with the morphology and physiology outcomes. These results demonstrate that the secondary metabolites of Scenedesmus sp. exert algal inhibition effect by breaked the membrane structure, destroyed the photosynthetic system of microalgae, inhibited amino acid synthesis, reduced antioxidant capacity, and eventually caused algal cell lysis and death. Our research provides a reliable basis for the biological control of cyanobacterial blooms on the one hand, and on other hand supply application of non-targeted metabolome on the study of microalgae allelochemicals.

Morphological change and differential proteomics analysis of gill in Mytilus coruscus under starvation.

Mytilus coruscus is a dominant shellfish in the Yangtze estuary and its adjacent sea area. Food deprivation often occurs during their growth due to fluctuations in algal abundance caused by seasonal freshwater flushing and high-density aquaculture mode. To investigate the coping strategies of M. coruscus to starvation stress, electron microscopy and differential proteomic analysis were performed on the critical feeding organ gill of the mussels after 9 days of starvation. The electron microscopy results showed that the cilia of the mussel gills were dissolved, and the gaps between gill filaments widened under starvation. Differential proteomic analysis revealed that phagocytosis-related proteins such as ATPeV1E, ATPeV1C, LAMP1_2 and CTSL were significantly upregulated, and the phagocytosis pathway was significantly enriched (p < 0.05). In addition, the corin content in gill and myeloperoxidase level as well as the number of dead cells in blood were both significantly increased (p < 0.05). What's more, proteomic data suggested that immune maintenance, cellular transport and metabolism related pathways were significantly enriched, which illustrated an immune and metabolism responses under starvation. This study reveals for the first time that phagocytosis functions as an essential strategy for M. coruscus to cope with starvation, which provides new scientific knowledge and a theoretical basis for understanding the adaptation mechanisms of mussel to starvation and for rational optimization of mussel culture patterns.

The phytochemical constituents and protective effect of Fritillaria hupehensis on acute lung injury.

Acute lung injury (ALI), a severe respiratory disorder, frequently develops into acute respiratory distress syndrome (ARDS) without timely treatment and scores highly in terms of morbidity and mortality rates. Fritillaria hupehensis is a famous traditional Chinese medicine with antitussive, expectorant and anti-asthmatic effect. Here, the effects of F. hupehensis extracts on lipopolysaccharide (LPS)-induced ALI mice were evaluated for the first time. We showed ethyl acetate fraction (EAF) significantly reduced the leukocytes and neutrophils of bronchoalveolar lavage fluid (BALF) and the lung index as well as pro-inflammatory cytokines (TNF-α and IL-6) of lung homogenates but increasing the anti-inflammatory cytokines (IL-4 and IL-10). Additionally, the alleviation of EAF treatment on lung injury was verified through histopathological observations. Subsequent phytochemical investigation on bioactive fraction led to isolation of 17 compounds including two new, in which compounds 2, 5 and 6 exhibited better anti-inflammatory effect on LPS-induced 16 human airway epithelial (16HBE) cells model by inhibiting the production of CRP and PCT. Furthermore, compound 2 suppressed the LPS-induced upregulation of proteins containing p-p65, COX-2, Caspase-1 and IL-18. In summary, F. hupehensis alleviating LPS-induced ALI in mice may be associated with the anti-inflammatory activity of steroidal alkaloids by suppressing the NF-κB-regulated pro-inflammatory proteins.

Comparative study of Janus B2XY (X, Y = S, Se, Te) and F-BNBN-H monolayers for water splitting: revealing the positive and negative roles of the intrinsic dipole.

It is widely recognized that the intrinsic dipole in two-dimensional (2D) photocatalysts promotes hydrogen production during water splitting. Herein, we wonder whether the intrinsic dipole plays a negative role in water splitting. In this work, we make a comparative study of the structural, electronic, and photocatalytic properties of Janus B2XY (X, Y = S, Se, Te) and F-BNBN-H monolayers using first principles. Our theoretical results reveal that both B2XY and F-BNBN-H monolayers exhibit spatially separated conduction band minimum (CBM) and valence band maximum (VBM), as well as vacuum level differences at the opposite surfaces due to the intrinsic dipole. The F-BNBN-H monolayer has excellent redox ability for water splitting, because its CBM is located at the surface with a lower vacuum level and its VBM is distributed on the opposite surface possessing a higher vacuum level. By sharp contrast, B2XY monolayers have limited or vanishing redox ability, because their CBM is located at the surface with a higher vacuum level and their VBM is distributed on the opposite surface with a lower vacuum level. This work emphasizes the negative role of vacuum level differences of photocatalysts caused by the intrinsic dipole in water splitting.

Sinuscalide A: An Antiviral Norcembranoid with an 8/8-Fused Carbon Scaffold from the South China Sea Soft Coral Sinularia scabra.

Sinuscalide A (1), featuring an uncommon 8/8-fused carbon scaffold, three new norditerpenes, sinuscalides B-D (2-4), and sinuscatone A (5), with a 5/4/9 tricyclic carbon ring system, along with four known compounds were isolated from the South China Sea soft coral Sinularia scabra. The structures of the new compounds were established by extensive spectroscopic analysis, X-ray diffraction, and electronic circular dichroism (ECD). A plausible biosynthetic pathway for 1 was proposed. In a bioassay, compound 1 showed antiviral activity against human enterovirus EV71 (IC50 = 5.0 µM) and an inhibitory effect against RANKL-induced osteoclastogenesis (92.3% inhibition at 10 µM). Compound 5 exhibited mild inhibition against Streptococcus pneumoniae and Salmonella paratyph (MIC 16 µg/mL).

Integrated Analyses of miRNome and Transcriptome Reveal the Critical Role of miRNAs Toward Heat Stress Response in Isochrysis galbana.

Isochrysis galbana is widely used in aquaculture as a bait microalgal species. High temperature (HT) can severely impair the development of I. galbana, exerting adverse effects on its yield. MicroRNAs (miRNAs) play an essential role in modulating stress-responsive genes. However, the role of miRNAs in response to HT in microalgae remains largely unexplored. In the present study, we identified several conserved and novel miRNAs in I. galbana through miRNome sequencing. Among these identified miRNAs, 22 miRNAs were differentially expressed in response to heat stress, and their target genes were predicted accordingly. Moreover, a comprehensive and integrated analysis of miRNome and transcriptome was performed. We found that six potential reversely correlated differentially expressed miRNA (DEM) and differentially expressed gene (DEG) pairs were associated with heat stress response (HSR) in I. galbana. The expressions of DEMs and DEGs were further verified using real-time quantitative PCR (RT-qPCR). Integrated analyses showed that miRNAs played fundamental roles in the regulatory network of HSR in I. galbana mainly by regulating some heat-responsive genes, including heat shock proteins (HSPs), reactive oxygen species (ROS) signaling-related genes, and specific key genes in the ubiquitination pathway. Our current study identified the first set of heat-responsive miRNAs from I. galbana and helped elucidate the miRNA-mediated HSR and resistance mechanisms in I. galbana. This new knowledge could provide ways to enhance its heat stress tolerance.

The Protective Effect of Sweet Potato Root Tuber on Chemotherapy-Induced Thrombocytopenia.

SCOPE: Sweet potato (Ipomoea batatas L.) is one of the leading crops worldwide, containing high nutritional components such as fiber and polyphenols. Root tuber of Simon 1 (SIMON), a cultivar of sweet potato, is a folk food in China with a hemostasis function but lacking experimental data support. METHODS AND RESULTS: Now the protective effect of SIMON on chemotherapy-induced thrombocytopenia (CIT), a serious complication of cancer treatment, is investigated for the first time by a CIT mouse model induced by intraperitoneal injection of carboplatin. As a result, SIMON raises the number of peripheral platelets, white blood cells, and bone marrow nucleated cells in CIT mice significantly. Besides, carboplatin-induced atrophy of the thymus, spleen, and disordered metabolism of the inflammatory immune system and glycerophospholipids are also reversed by SIMON. Phytochemical analysis of SIMON indicates 16 compounds including eight phenolic derivatives, which might be associated with its anti-CIT bioactivity. CONCLUSION: Sweet potato (SIMON) may be an efficient function food in the prevention of bleeding disorders.

RNA-seq Insights Into the Impact of Alteromonas macleodii on Isochrysis galbana.

Phycospheric bacteria may be the key biological factors affecting the growth of algae. However, the studies about interaction between Isochrysis galbana and its phycospheric bacteria are limited. Here, we show that a marine heterotrophic bacterium, Alteromonas macleodii, enhanced the growth of I. galbana, and inhibited non-photochemical quenching (NPQ) and superoxide dismutase (SOD) activities of this microalgae. Further, we explored this phenomenon via examining how the entire transcriptomes of I. galbana changed when it was co-cultured with A. macleodii. Notable increase was observed in transcripts related to photosynthesis, carbon fixation, oxidative phosphorylation, ribosomal proteins, biosynthetic enzymes, and transport processes of I. galbana in the presence of A. macleodii, suggesting the introduction of the bacterium might have introduced increased production and transport of carbon compounds and other types of biomolecules. Besides, the transcriptome changed largely corresponded to reduced stress conditions for I. galbana, as inferred from the depletion of transcripts encoding DNA repair enzymes, superoxide dismutase (SOD) and other stress-response proteins. Taken together, the presence of A. macleodii mainly enhanced photosynthesis and biosynthesis of I. galbana and protected it from stress, especially oxidative stress. Transfer of fixed organic carbon, but perhaps other types of biomolecules, between the autotroph and the heterotroph might happen in I. galbana-A. macleodii co-culture. The present work provides novel insights into the transcriptional consequences of I. galbana of mutualism with its heterotrophic bacterial partner, and mutually beneficial associations existing in I. galbana-A. macleodii might be explored to improve productivity and sustainability of aquaculture algal rearing systems.

Quantitative analysis of carnosine, anserine, and homocarnosine in skeletal muscle of aquatic species from east China sea.

Histidine-containing dipeptides (HCDs) are a family of non-protein, nitrogen-containing compounds with multiple physiological roles and are mainly present in excitable tissues of vertebrates. The distribution of HCDs in various animal species has been the subject of study for nearly 100 years. The aim of this research was to determine the content of the HCDs in the aquatic species collected from the Zhoushan fishing ground of the East China Sea. Using LC-MS/MS technology, the occurrence of carnosine, anserine, and homocarnosine in skeletal muscle of 38 aquatic species (26 teleosts, 6 molluscs, and 6 crustaceans) and chicken breast was investigated. Of the 38 aquatic species examined, 24 species (23 teleosts and 1 mollusc) contained considerable amounts (>5 ng/g wet tissue) of HCDs, and anserine was the major component of HCDs in their skeletal muscles. Only 5 teleosts contained homocarnosine. Most invertebrates, with the exception of the sepia Uroteuthis chinensis, did not contain HCDs. The present findings greatly expand the HCD distribution data and provide insight into understanding the roles of HCDs in different animals and a nutritional assessment for marine aquatic species.

[Molecular mechanism analysis of Erzhi Wan in treatment of aging based on network pharmacology].

This present study aimed to explore the molecular mechanism of Erzhi Wan(a prescription of nourishing Yin and toni-fying liver and kidney) in treatment of aging by network pharmacology. The active constituents and target proteins of Erzhi Wan were searched from Traditional Chinese Medicine Systems Pharmacology Database(TCMSP) and PubChem databases respectively. Aging-related genes were searched from Gene and HAGR databases. Based on the Ingenuity Pathway Analysis(IPA), we analyzed the common molecular network, biological pathway and interaction sites between these two parts, and verified some of them by Western blot. Twelve active constituents of Erzhi Wan were screened by TCMSP databases, 69 protein targets were predicted through PubChem, and 148 aging-related genes were found in Gene and HAGR databases. IPA comparison showed that the molecular networks of these two were complex, with diversity of biological functions. The common pathways involved 292 pathways, mainly related to tumors. They acted on hypoxia inducible factor-1α gene(HIF1α), nuclear factor-E2 related factor(Nrf2/NFE2 L2), tumor necrosis factor(TNF) and other sites. Western blot results suggested that Erzhi Wan could down-regulate the expression of HIF1α, with statistical difference(P<0.05). It was concluded that, Erzhi Wan could intervene aging through improving pseudo-hypoxic microenvironment and inflammation. The molecular mechanism of Erzhi Wan in delaying aging was preliminarily revealed, which laid a foundation for further stu-dying the anti-aging mechanism of Erzhi Wan, and also provided a reference for the compatibility mechanism and extended application of Chinese medicine compounds.

Molecular method for rapid detection of the red tide dinoflagellate Karenia mikimotoi in the coastal region of Xiangshan Bay, China.

The species Karenia mikimotoi is a common nearshore red tide alga that can secrete hemolytic exotoxin and ichthyotoxin, which can induce the death of fish and shellfish, causing severe economic losses. In this study, loop-mediated isothermal amplification (LAMP) was employed in combination with the lateral flow dipstick (LFD) visual detection method to establish the LAMP-LFD rapid detection method for K. mikimotoi. The internal transcribed spacer ITS1-5.8S-ITS2 of K. mikimotoi was used as the target sequence and was amplified with specific primers designed in this study. The results indicated that the amplification optimal reaction conditions for LAMP in this paper were for 20 min at 65 °C. Moreover, LAMP had excellent specificity, showing negative results for other common red tide causing algal species. In field samples, we successfully reduced the total time, with only 23 min needed from LAMP amplification to LFD result display, which was shorter than that of conventional PCR. Consequently, LAMP-LFD should be useful for rapid field detection of low-density K. mikimotoi and for the early prevention of red tide induced by such algae.

[Effects of heterogeneous distribution of soil resources on the growth of Chinese fir seedlings under warming]. / 增温下土壤资源异质分布对杉木幼苗生长的影响.

A three-factor experiment with air temperature manipulation, soil temperature manipulation and nutrients distribution pattern was conducted in Forest Ecosystem and Global Change Research Station of Fujian Normal University in Chenda, Sanming, Fujian Province. We examined the effects of heterogeneous distribution of soil resources and warming on underground and aboveground growth of Chinese fir (Cunninghamia lanceolata) seedlings, and whether warming could change the recognition of fine roots to the heterogeneous distribution of soil resources, to understand the response of Chinese fir seedlings to heterogeneous distribution of soil resources under the background of global warming. The results showed that the recognition degree of Chinese fir to the nutrients distribution pattern was mainly reflected by the absorbing root (0-1 mm diameter class) rather than by the 1-2 mm diameter class fine roots. There were no significant effects of warming on the ratio of fine root biomass between nutrient-poor and nutrient-rich patches, the coefficient of nutrients-avoidance and the coefficient of nutrients-preference of fine roots of young Chinese fir except for the single air warming. Chinese fir had higher fine root biomass (0-1 mm diameter class) and lower height in the heterogeneous soil resource environment. Air warming decreased the biomass of fine roots (both 0-1 and 0-2 mm diameter classes) and increased the height of trees. Soil warming decreased the fine root biomass of 1-2 mm diameter class and increased the height of trees and the length of lateral branches. There was no significant interactive effect of air warming, soil warming and heterogeneity of soil resource on aboveground and belowground growth of Chinese fir. The results demonstrated that the absorbing roots of Chinese fir seedlings could recognize the heterogeneous distribution of soil resources,which was not altered by warming.

Sarocladione, a unique 5,10:8,9-diseco-steroid from the deep-sea-derived fungus Sarocladium kiliense.

A novel ergostane, sarocladione (1), was isolated from the deep-sea-derived fungus Sarocladium kiliense, along with 20 known compounds. The structure of 1 was determined mainly by a detailed analysis of its experimental and calculated NMR spectroscopic data. It is worth noting that 1 was the first steroid bearing a 5,10:8,9-diseco moiety. All 21 compounds were tested for in vitro antitumor activities against five cancer cell lines. ß-Sitostenone (7) and 4,6-dihydroxyeudesmane (20) showed significant effects on HeLa-S3 cells with the IC50 values of 9.2 µM and 9.3 µM, respectively.

Bacterial Community Diversity and Screening of Growth-Affecting Bacteria From Isochrysis galbana Following Antibiotic Treatment.

Algal cultures are generally co-cultures of algae and bacteria, especially when considering outdoor cultivation. However, the effects of associated bacteria on algal growth remain largely unexplored, particularly in the context of Isochrysis galbana. In the present study, we investigated the effects of antibiotic on the growth of I. galbana and its associated bacterial community. We found advantageous responses of I. galbana to antibiotic exposure, evidenced by the increased growth, and the maximal photochemical efficiency of PSII (Fv/Fm). Since antibiotics can cause major disturbances within bacterial community, we further conducted 16S rDNA amplicon sequencing to determine the changes of bacterial community diversity following antibiotic treatment. We found that antibiotic treatment considerably and negatively affected the abundance and diversity of bacterial community, and 17 significantly decreased bacterial species in the antibiotic-treated medium, including Pseudomonas stutzeri, were identified. Further co-culture experiments revealed that P. stutzeri inhibited the growth of I. galbana, and the inhibitory activity was retained in the cell-free bacterial filtrate. These results indicated that the negative effect of bacteria was not exclusively transmitted through contact with I. galbana but could be also mediated via secretory compounds. Taken together, our findings not only fully characterized the bacterial community associated with I. galbana and how the bacterial community changed in response to antibiotic perturbations, but also provided a valuable information about the interactions between I. galbana and its associated bacteria, which might help improve the yield, and quality of I. galbana during its cultivation processes.

Distribution of Karlodinium veneficum in the coastal region of Xiangshan Bay in the East China Sea, as detected by a real-time quantitative PCR assay of ribosomal ITS sequence.

Athecate dinoflagellate Karlodinium veneficum is a universal toxic species possessing karlotoxins recognized especially as ichthyotoxic as well as cytotoxic and hemolytic. Blooms of K. veneficum, both single-species or accompanied with other species, occurred more frequently worldwide in recent years, including the coastal region of China. Normally, K. veneficum present in relatively low abundance in phytoplankton communities in estuary regions. Being small and difficult to identify with light microscopy, it has been ignored for a long time till its blooming and toxins being confirmed. How it presents in background level and what is its relationship with critical geological and hydrological environment factors are basically not clear. In this study, the paper reports the application of a real-time quantitative PCR (qPCR) method to investigate the abundance and distribution of K. veneficum in the coastal waters of Xiangshan Bay in the East China Sea (ECS), a typical bay area of harmful algae blooms and heavily affected by anthropogenic activities. The real-time qPCR assay came out being an efficient method at detecting even low cell densities of K. veneficum of different genotypes. A total of 38 field samples of surface (0.5 m) and bottom water (9-100 m in depth) were analyzed and 12 samples were found positive for K. veneficum. At least 3 genotypes of K. veneficum present in this region. Temperatures in sites of K. veneficum positive ranged from 21.7 to 23.4 °C, and salinity levels were between 21.1 and 26.3. The K. veneficum distributed quite extensively in the waters of Xiangshan Bay, cell abundance varied from a low of 4 cells/L to a maximum of 170 cells/L. Most of the samples containing K. veneficum were collected from bottom water in different sites. At three of the 19 sampling sites, K. veneficum was detected in both surface and bottom water samples. Especially at sampling site near Beilun port, where the water is typically muddy with low transparency, relative high cell numbers of K. veneficum were found in both surface and bottom waters. Mixotrophy and vertical migration of K. veneficum could be important eco-physiological factors to consider in terms of understanding these distribution characteristics. The ideal conditions for K. veneficum growth and aggregation in this area still needs further study.

One-Step Bioconversion of Fatty Acids into C8-C9 Volatile Aroma Compounds by a Multifunctional Lipoxygenase Cloned from Pyropia haitanensis.

The multifunctional lipoxygenase PhLOX cloned from Pyropia haitanensis was expressed in Escherichia coli with 24.4 mg·L-1 yield. PhLOX could catalyze the one-step bioconversion of C18-C22 fatty acids into C8-C9 volatile organic compounds (VOCs), displaying higher catalytic efficiency for eicosenoic and docosenoic acids than for octadecenoic acids. C20:5 was the most suitable substrate among the tested fatty acids. The C8-C9 VOCs were generated in good yields from fatty acids, e.g., 2E-nonenal from C20:4, and 2E,6Z-nonadienal from C20:5. Hydrolyzed oils were also tested as substrates. The reactions mainly generated 2E,4E-pentadienal, 2E-octenal, and 2E,4E-octadienal from hydrolyzed sunflower seed oil, corn oil, and fish oil, respectively. PhLOX showed good stability after storage at 4 °C for 2 weeks and broad tolerance to pH and temperature. These desirable properties of PhLOX make it a promising novel biocatalyst for the industrial production of volatile aroma compounds.