Interannual Variation of the Onset of Yunnan’s Rainy Season and Its Relationships with the Arctic Oscillation of the Preceding Winter

Based on an analysis of the circulation in May associated with the interannual variation of the onset of Yunnan’s rainy season, this study examined the rela-tionship between Arctic Oscillation (AO) and the onset timing of the rainy sea-son by using the NCEP/NCAR reanalysis and observational precipitation data for 1961-2010. The results indicated that, on an interannual time scale, intense Asian summer monsoon and an active EU-pattern wave train circulation in its positive phase, associated with a cold cyclonic cell covering the western part of the East Asian subtropical westerly jet (EASWJ), jointly contributed to the onset of the rainy season in May. Otherwise, the onset might be suppressed. The cold cyclonic cell over East Asia likely led to the southward shift and enhancement of EASWJ as well as its secondary circulation around the jet entrance, which could provide a favorable dynamic and thermal condition for rainfalls in Yunnan as was revealed in previous studies on 10 - 30-day time scale. Further examination showed that the preceding wintertime AO played a significant role in the timing of the onset of the rainy season before the mid-1980s’ by mostly modulating the wave-train-like circulation over East Asia in May. During that time period, when the AO index of the previous winter was positive (negative), Yunnan’s rainy season tended to begin earlier (later) than normal. Correspond-ingly, the precipitation in May was also closely linked to wintertime AO.

Influence of Springtime Atlantic SST on ENSO:Role of the Madden-Julian Oscillation

Increased evidence has shown the important role of Atlantic sea surface temperature(SST) in modulating the El Nio-Southern Oscillation(ENSO). Persistent anomalies of summer Madden-Julian Oscillation(MJO) act to link the Atlantic SST anomalies(SSTAs) to ENSO. The Atlantic SSTAs are strongly correlated with the persistent anomalies of summer MJO, and possibly affect MJO in two major ways. One is that an anomalous cyclonic(anticyclonic) circulation appears over the tropical Atlantic Ocean associated with positive(negative) SSTA in spring, and it intensifies(weakens) the Walker circulation. Equatorial updraft anomaly then appears over the Indian Ocean and the eastern Pacific Ocean, intensifying MJO activity over these regions. The other involves a high pressure(low pressure) anomaly associated with the North Atlantic SSTA tripole pattern that is transmitted to the mid-and low-latitudes by a circumglobal teleconnection pattern, leading to strong(weak) convective activity of MJO over the Indian Ocean. The above results offer new viewpoints about the process from springtime Atlantic SSTA signals to summertime atmospheric oscillation, and then to the MJO of tropical atmosphere affecting wintertime Pacific ENSO events, which connects different oceans.

EmbB and EmbC regulate the sensitivity of Mycobacterium abscessusto echinomycin

Treatment of Mycobacterium abscessus(Mab)infections is very challenging due to its intrinsic resistance to most available drugs.Therefore,it is crucial to discover novel anti-Mab drugs.In this study,we explored an intrinsic resistance mechanism through which Mab resists echinomycin(ECH).ECH showed activity against Mab at a minimum inhibitory concentration(MIC)of 2μg/ml.A embC strain in which the embC gene was knocked out showed hypersensitivity to ECH(MIC:0.0078-0.0156μg/ml).The MICs of ECH-resistant strains screened with reference to AembC ranged from 0.25 to 1μg/ml.Mutations in EmbB,including D306A,D306N,R350G,V555l,and G581S,increased the Mab's resistance to ECH when overexpressed in AembC individually(MIC:0.25-0.5μg/ml).These EmbB mutants,edited using the CRISPR/Cpf1 system,showed heightened resistance to ECH(MIC:0.25-0.5μg/ml).The permeability of these Mab strains with edited genes and overexpression was reduced,as evidenced by an ethidium bromide accumulation assay,but it remained significantly higher than that of the parent Mab.In summary,our study demonstrates that ECH exerts potent anti-Mab activity and confirms that EmbB and EmbC are implicated in Mab's sensitivity to ECH.Mutation in EmbB may partially compensate foralossof EmbCfunction.

珊瑚来源真菌Parengyodontium album SCSIO SX7W11中聚酮化合物的发现及其生物合成途径分析

海洋来源真菌的天然产物因其独特的结构与生物学活性而备受关注,而利用基因组信息对其代谢产物进行深入挖掘也成为研究策略之一。【目的】本文以一株南海珊瑚来源的真菌Parengyodontium album SCSIO SX7W11为目标菌株,挖掘其生产聚酮类化合物的潜能。【方法】本研究利用Illumina Miseq技术对SX7W11菌株进行全基因组扫描测序,运用生物信息学手段对其基因组的生物合成基因簇进行预测和基因功能注释,挖掘可能产生新颖聚酮化合物的基因簇。对SX7W11进行放大发酵后,利用正相色谱、中压反相色谱、Sephadex LH-20凝胶色谱、HPLC半制备等分离手段分离纯化出单体化合物。再利用高分辨质谱(HR-ESI-MS)、^(1)H NMR、^(13)C NMR、X-ray单晶衍射等波谱手段确定化合物的结构,并根据生物合成基因簇对化合物的生物合成途径进行推导。【结果】全基因组扫描测序结果显示,P.album SCSIO SX7W11基因组大小为34.0 Mb,含有24个生物合成基因簇,包括6个聚酮合酶基因簇以及3个萜烯合酶基因簇。从发酵产物中分离鉴定到3个聚酮类化合物:emodin(1)、alternaphenol B(2)和sydowinin A(3),其中化合物3获得了单晶结构数据。通过生物信息学方法从菌株基因组中定位到了sydowinin A的生物合成基因簇。结合文献对emodin(1)、alternaphenol B(2)和sydowinin A(3)的生物合成途径进行了分析。【结论】本研究通过基因组挖掘及培养基优化,发现1株珊瑚来源的真菌P.album SCSIO SX7W11具有生产sydowinins类聚酮类化合物的能力,为该类化合物生物合成机制深入研究奠定了基础。

Characterization of the depsidone gene cluster reveals etherification,decarboxylation and multiple halogenations as tailoring steps in depsidone assembly

Depsides and depsidones have attracted attention for biosynthetic studies due to their broad biological activities and structural diversity.Previous structure-activity relationships indicated that triple halogenated depsidones display the best anti-pathogenic activity.However,the gene cluster and the tailoring steps responsible for halogenated depsidone nornidulin(3)remain enigmatic.In this study,we disclosed the complete biosynthetic pathway of the halogenated depsidone through in vivo gene disruption,heterologous expression and in vitro biochemical experiments.We demonstrated an unusual depside skeleton biosynthesis process mediated by both highly-reducing polyketide synthase and nonreducing polyketide synthase,which is distinct from the common depside skeleton biosynthesis.This skeleton was subsequently modified by two in-cluster enzymes DepG and DepF for the ether bond formation and decarboxylation,respectively.In addition,the decarboxylase DepF exhibited substrate promiscuity for different scaffold substrates.Finally,and interestingly,we discovered a halogenase encoded remotely from the biosynthetic gene cluster,which catalyzes triple-halogenation to produce the active end product nornidulin(3).These discoveries provide new insights for further understanding the biosynthesis of depsidones and their derivatives.

Enzymatic Synthesis of a Diastereomer of Neoabyssomicin Derivative Using the Diels-Alderase AbyU

Main observation and conclusion The enzyme AbyU catalyses a Diels-Alder(DA)reaction during abyssomicin C biosynthesis.In this study,AbyU is shown to convert the native substrate of another Diels-Alderase(DAase),AbmU,to a new abyssomicin derivative,abyssomicin 7.

Member of Editorial Board of Rising Stars

Discovery and Biosynthesis of Marine Derived Bioactive Natural Products It has been demonstrated that natural products still play a pivotal role in new drug discovery. The novel scaffolds found within nature far exceed the imagination and synthetic capabilities of chemists, The underexplored marine microorganisms have been recognized as an exciting resource in supplying novel chemoWpes. We are focusing on the screening, fermentation, and discovery of bioactive natural products from marine actinobacteria and fungi, and therefore to obtain fundamentally new, clinically useful drug leads.[1,2]