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大亚湾大型底栖动物近30年次级生产力变化特征
No full text利用1988年1月和7月,2004年3月、5月、9月和12月,2008年3月、5月、9月和12月以及2015年2月、8月、11月和12月在大亚湾海域开展的共计14航次、200站次的大型底栖动物调查结果,根据Brey经验公式计算大型底栖动物次级生产力和次级生产力与生物量的比值(P/B值),分析近30年次级生产力变化特征。结果表明:1)以去灰干质量(ash free dry mass,AFDM)计,大亚湾4个时段大型底栖动物次级生产力分别为7.44 g·(m2·a)–1、11.34 g·(m2·a)–1、4.91 g·(m2·a)–1和2.93 g·(m2·a)–1,P/B值分别为0.76 a–1、0.86 a–1、0.79 a–1和0.47 a–1,均呈1988—2004年升高、2004—2015年降低的趋势。2)各类群次级生产力和P/B值变化趋势存在一定差异。其中软体动物、多毛类、甲壳类次级生产力和P/B值呈1988—2004年升高、2004年后降低的趋势;棘皮动物则均呈持续降低的趋势。3)综合各类群次级生产力平面分布图,湾顶西北部和大鹏澳附近海域变化明显。相关性分析显示,底栖动物次级生产力与海水无机氮、磷酸盐、溶解氧浓度和沉积物有机碳含量显著相关
一个新颖南极微生物酯酶EST112-2的功能鉴定和在手性叔醇(S)-芳樟醇制备中的应用（英文）
No full text手性叔醇是合成药物和一些香料产品的非常重要中间体.芳樟醇是叔醇的一种,不同构型的芳樟醇具有不同的香气.因此如何研发合适的制备方法以获得高光学纯度的芳樟醇等叔醇是急需解决的技术问题.生物酶催化合成符合绿色化学的理念,但是由于叔醇化学结构中的空间位阻影响,使用生物酶催化的拆分反应制备高光学纯度的叔醇比较困难.对来自南极微生物的一个新的酯酶EST112-2进行了功能鉴定,并将其作为合成手性芳樟醇的生物催化剂.EST112-2可以通过不对称水解乙酸芳樟酯获得(S)-芳樟醇.对反应的p H、温度、共溶剂、底物浓度、催化剂用量以及反应时间等参数进行优化,EST112-2制备的(S)-芳樟醇的光学纯度大于66%,得率超过72%.EST112-2制备的(S)-芳樟醇的光学纯度要远远高于以往报道
有机物消耗对珠江口沉积物反硝化和厌氧氨氧化过程的影响
No full text反硝化及厌氧氨氧化是两个主要的氮汇途径,能有效地将生态系统中的固定氮转化为N_2或N_2O释放到大气中。利用微宇宙与中宇宙模拟实验,本研究系统地分析了有机物的种类、可利用性和浓度大小对珠江口沉积物反硝化和厌氧氨氧化过程的影响。研究结果表明:有机物的消耗能显著提高反硝化的活性,不同种类的有机物表现出不同的活性,简单的小分子有机物活性最高,复杂有机物次之,惰性有机物则难以被利用。然而,有机物对厌氧氨氧化过程的促进并不显著,这主要与其自养型的代谢方式有关。中宇宙实验室进一步表明,有机物的消耗不但给反硝化过程提供了能源,而且由于有机物分解消耗氧气,为反硝化过程的发生提供了必要的环境条件。在有机物负荷状态下,反硝化过程在珠江口沉积物的脱氮过程中发挥主导作用。总之,沉积物中微生物脱氮是依赖有机物消耗的过程,表现出强烈的碳氮代谢耦合
Simultaneous removal of Cu2+ and bisphenol A by a novel biochar-supported zero valent iron from aqueous solution: Synthesis, reactivity and mechanism
No full textIn this study, a novel biochar-supported zero valent iron (BC-nZVI) was synthesized through a green method. A high performance on the simultaneous removal of Cu2+ and bisphenol A (BPA) by a combination of BC-nZVI with persulfate (BC-nZVI/PS) system was successfully achieved. The simultaneous efficiencies of Cu2+ and BPA could reach 96 and 98% within 60 min, respectively. Both HO center dot and SO4 center dot- were two major reactive species in BC-nZVI/PS system, and SO4 center dot- was primary radical responsible for the degradation of BPA. Four kinds of Cu species, such as Cu(OH)(2), CuO, Cu2O and Cu-0 were generated via the adsorption and reduction of the BC-nZVI, whereas six kinds of products of BPA including p-isopropenyl phenol and 4-isopropylphenol were generated via the combined oxidation of SO4 center dot- and HO center dot. The possible reaction mechanism for the simultaneous removal of Cu2+ and BPA by BC-nZVI/PS system contained a synergistic effect between the reduction of Cu2+ and the oxidation of BPA. This is the first report on the feasibility of the remediation of coexistence of heavy metal and organic compound in aquatic environment using the BC-nZVI/PS system. (C) 2018 Elsevier Ltd. All rights reserved
Structurally Diverse Polyketides From the Mangrove-Derived Fungus Diaporthe sp SCSIO 41011 With Their Anti-influenza A Virus Activities
No full textInfluenza A virus (IAV) is a severe worldwide threat to public health and economic development due to its high morbidity and mortality. Marine-derived fungi have been evidenced as a prolific source for the discovery of pharmacologically-active lead compounds. During the course of our search for novel bioactive substances from marine microorganisms, six new polyketides, including two octaketides (1-2), one chromone derivative (13), two highly substituted phthalides (17-18), and one alpha-pyrone derivative (21) along with 22 known congeners were isolated from a mangrove-associated fungus Diaporthe sp. SCSIO 41011. Their structures were determined by spectroscopic analysis and by comparison with literature data. And the absolute configurations were established according to the specific rotation or electron circular dichroism method. Antiviral evaluation results revealed that compounds 14, 15, 26, and 5-chloroisorotiorin displayed significant anti-IAV activities against three influenza A virus subtypes, including A/Puerto Rico/8/34 H274Y (H1N1), A/FM-1/1/47 (H1N1), and A/Aichi/2/68 (H3N2), with IC50 values in the range of 2.52-39.97 mu M. The preliminary structure-activity relationships (SARs) are also discussed. These findings expand the chemical and bioactive diversity of polyketides derived from the genus Diaporthe, and also provide a basis for further development and utilization of chromone, xanthone, and chloroazaphilone derivatives as source of potential anti-viral chemotherapy agents
Effects of acclimation on arsenic bioaccumulation and biotransformation in freshwater medaka Oryzias mekongensis after chronic arsenic exposure
No full textFish can acclimate to chronic arsenic (As) exposure, but the mechanisms of acclimation remain unclear to date. Therefore, this study conducted 28-d chronic inorganic As [As(III) and As(V)I exposures in fresh-water medaka (Oryzias mekongensis), examined the As bioaccumulation and biotransformation during exposure, and the As acute toxicity and toxicokinetics after exposure. After chronic As(V) exposure, the 96-h lethal concentration (96-h LC50) of As(V) increased 1.3-fold (from 223 to 286 mu mol/L), indicating that the fish became more tolerant to As(V). The As bioaccumulation in As(V)-exposed fish increased gradually during the initial 21-d exposure period and then decreased at 28 d, indicating that acclimation occurred to regulate the total As levels. Toxicokinetics measurement suggested that As(V) uptake (uptake rate constant, k(u)) was significantly decreased and As(III) elimination (efflux rate constant, k(e1)) was significantly increased, both of which could reduce As bioaccumulation. Furthermore, the organic As species became more predominant (50.1-69.3%) in exposed fish, while the inorganic As species were predominant (53.6-56.4%) in the control fish, suggesting that the capability of As biotransformation increased to acclimate inorganic As during chronic exposure. In summary, this study elucidated the acclimation strategies (reduced bioaccumulation and increased biotransformation) of O. mekongensis to counter the ambient As contamination. (C) 2018 Elsevier Ltd. All rights reserved
Activated production of silent metabolites from marine-derived fungus Penicillium citrinum
No full textAs an attempt to utilize of rare earth elements as a novel method to activate the silent genes in fungus, the marine-derived fungus Penicillitan citrinum was cultured under ordinary laboratory fermentation conditions in the presence of scandium chloride (ScCl3, 50 mu M), and chemical investigation led to the isolation and characterization of three new peptide derivatives (1-3), along with four known pyrrolidine alkaloids (4-7). Those structures were elucidated by spectroscopic data interpretation, as well as chemical reactions. Comparative metabolic profiling of the culture extracts (with/without scandium chloride) indicated that compounds 1-3 scarcely detected in the absence of ScCl3. In addition, the antibacterial and cytotoxic activities of all isolated products were evaluated
Nitrogen deposition in precipitation to a monsoon-affected eutrophic embayment: Fluxes, sources, and processes
No full textDaya Bay in the South China Sea (SCS) has experienced rapid nitrogen pollution and intensified eutrophication in the past decade due to economic development. Here, we estimated the deposition fluxes of nitrogenous species, clarified the contribution of nitrogen from precipitation and measured ions and isotopic composition (delta N-15 and delta O-18) of nitrate in precipitation in one year period to trace its sources and formation processes among different seasons. We found that the deposition fluxes of total dissolved nitrogen (TDN), NO3-, NH4+, NO2-, and dissolved organic nitrogen (DON) to Daya Bay were 132.5, 64.4 17.5, 1.0, 49.6 mmol m(-2.)yr(-1), respectively. DON was a significant contributor to nitrogen deposition (37% of TDN), and NO3- accounted for 78% of the DIN in precipitation. The nitrogen deposition fluxes were higher in spring and summer, and lower in winter. Nitrogen from precipitation contributed nearly 38% of the total input of nitrogen (point sources input and dry and wet deposition) in Daya Bay. The delta N-15-NO3- abundance, ion compositions, and air mass backward trajectories implicated that coal combustion, vehicle exhausts, and dust from mainland China delivered by northeast monsoon were the main sources in winter, while fossil fuel combustion (coal combustion and vehicle exhausts) and dust from PRD and southeast Asia transported by southwest monsoon were the main sources in spring; marine sources, vehicle exhausts and lightning could be the potential sources in summer. delta O-18 results showed that OH pathway was dominant in the chemical formation process of nitrate in summer, while N2O5 + DMS/HC pathways in winter and spring
Season structures prokaryotic partners but not algal symbionts in subtropical hard corals
No full textCoral reef ecosystems have great economic, social, and ecological value. The ecological success of coral reef ecosystems critically depends on coral-algal symbiosis and coral-prokaryotic partnership. However, seasonal changes underlying these relationships in subtropical hard corals of Hong Kong are poorly studied. Here, we compared the community changes of algal symbionts and prokaryotic partners in Platygyra carnosa and Galaxea fascicularis from Hong Kong collected at two seasonal time points of winter and summer via massively parallel sequencing of genetic markers and multivariate analysis. The results indicated that algal symbionts showed no significant changes between the two seasonal time points but prokaryotic partners changed substantially. Prokaryotic partners putatively involved in photosynthesis, nitrogen fixation, and sulfur oxidation increased significantly from winter to summer, while prokaryotic partners potentially associated with chemosynthesis, ammonia oxidation, and nitrite oxidation decreased significantly from winter to summer. Dissolved oxygen and pH served as the main contributors influencing prokaryotic partners in winter, while temperature, turbidity, and salinity played a dominant role in shaping prokaryotic partners in summer. The findings of the present study suggest that season structures prokaryotic partners but not algal symbionts in subtropical hard corals
Overexpression of a type III PKS gene affording novel violapyrones with enhanced anti-influenza A virus activity
No full textBackground: Type III polyketide synthases (PKSs) are simple homodimer ketosynthases that distribute across plants, fungi, and bacteria, catalyzing formation of pyrone-and resorcinol-types aromatic polyketides with various bioactivities. The broad substrate promiscuity displayed by type III PKSs makes them wonderful candidates for expanding chemical diversity of polyketides. Results: Violapyrone B (VLP B, 10), an alpha-pyrone compound produced by deepsea-derived Streptomyces somaliensis SCSIO ZH66, is encoded by a type III PKS VioA. We overexpressed VioA in three different hosts, including Streptomyces coelicolor M1146, Streptomyces sanyensis FMA as well as the native producer S. somaliensis SCSIO ZH66, leading to accumulation of different violapyrone compounds. Among them, S. coelicolor M1146 served as the host producing the most abundant violapyrones, from which five new (2-4, 7 and 12) and nine known (1, 5, 6, 8-11, 13 and 14) compounds were identified. Anti-influenza A (H1N1) virus activity of these compounds was then evaluated using ribavirin as a positive control (IC50 = 112.9 mu M), revealing that compounds 11-14 showed considerable activity with IC50 values of 112.7, 26.9, 106.7 and 28.8 mu M, respectively, which are significantly improved as compared to that of VLP B (10) (IC50 > 200 mu M). The productions of 10 and 13 were increased by adding P450 inhibitor metyrapone. In addition, site-directed mutagenesis experiment led to demonstration of the residue S242 to be essential for the activity of VioA. Conclusions: Biological background of the expression hosts is an important factor impacting on the encoding products of type III PKSs. By using S. coelicolor M1146 as cell factory, we were able to generate fourteen VLPs compounds. Anti-H1N1 activity assay suggested that the lipophilic nature of the alkyl chains of VLPs plays an important role for the activity, providing valuable guidance for further structural optimization of VLPs