FR901464, an antitumor natural product, represents a new class of potent anticancer small molecules targeting spliceosome and inhibiting both splicing and nuclear retention of pre-mRNA. Herein we describe the biosynthetic gene cluster of FR901464, identified by degenerate primer PCR amplification of a gene encoding the 3-hydroxy-3-methylglutaryl-CoA synthase (HCS) postulated to be involved in the biosynthesis of a β-branched polyketide from Pseudomonas sp. No. 2663. This cluster consists of twenty open reading frames (ORFs) and was localized to 93-kb DNA segment, and its involvement in FR901464 biosynthesis was confirmed by gene inactivation and complementation. FR901464 is biosynthesized by a hybrid polyketide synthase (PKS)/nonribosomal peptide synthetase (NRPS), HCS, and acyltransferases (AT)-less system. The PKS/NRPS modules feature unusual domain organization including multiple domain redundancy, inactivation, and tandem. Biochemical characterization of a glyceryl transferase and an acyl carrier protein (ACP) in the start module revealed that it incorporates D-1,3-bisphosphoglycerate, which is dephosphorylated and transferred to ACP as the starter unit. Furthermore, an oxidative Baeyer-Villiger reaction followed by chain release was postulated to form a pyran moiety. On the basis of in silico analysis and genetic and biochemical evidances, a biosynthetic pathway for FR901464 was proposed, which sets the stage to further investigate the complex PKS biochemically and engineer the biosynthetic machinery for the production of novel analogues.

The ecological and environmental consequences of large dam projects have received increasing attention in the recent decades. On the basis of daily water‐level data, six periods of TM/ETM+ data and a digital elevation model, the eco‐hydrological environments and vegetation area of East Dongting Lake, were compared for the years 1995–2011, spanning periods before and after the implementation of the Three Gorges Dam (TGD) in 2003. Vegetation area (including three types: forestry, reed and grass) continuously expanded, and the minimum elevation of vegetation‐covered area (VCA) gradually decreased by 0·88 m from 1995 to 2011. Following the implementation of the TGD, the rates of both vegetation expansion (12·3 vs 14·1 km2 year−1) and the lowering of minimum elevation of VCA (3·1 vs 7·9 cm year−1) increased rapidly. Monthly water level decreased considerably from July to November, and annual submergence duration at elevations of 22–26 and 30 m was considerably decreased after the TGD was implemented. The average maximum submergence duration of VCA was 231 days. Almost equal linear equations describing elevation change from 1995 to 2011 indicated that the minimum elevation of VCA identified via analysis of TM/ETM+ images can be represented by the maximum submergence duration evaluated via daily water level. These data indicate that vegetation colonized the non‐vegetation area (including mud beach or water body) more quickly after the implementation of the TGD, due to the drastic changes in eco‐hydrological environments such as the decreasing water level and the minimum elevation of VCA. The present methodology might allow faster and more reliable assessment of inundation related landscape impacts on a basin scale and thereby contribute to biodiversity monitoring and policy assessment. Copyright © 2014 John Wiley & Sons, Ltd.

Bacterial wilt, caused by Ralstonia solanacearum, is a devastating disease resulting in tremendous losses of economic crops such as plants in the Solanaceae. Recent studies showed that R. solanacearum is spreading from the lowlands to the highlands in China. We studied 97 Chinese R. solanacearum strains that were isolated from four tobacco-growing zones over a wide range of elevations using phylotype specific multiplex polymerase chain reaction (Pmx-PCR) and phylogenetic relationships (egl and mutS). The results showed that all isolates belonged to phylotype I, which were further clustered into eight egl-sequence type groups (egl-group, sequevar): sequevars 13, 14, 15, 17, 34, 44, 54, and 55. In addition, Sequevar 55, found from the highlands, was a new/unknown one. Southeast China (Z3) had the largest number of egl-groups, containing six sequevars. The basin of the Yangzi River (Z1) and southwestern China (Z2) contained five egl-groups. The basin of the Huai River (Z4), near the north of China, where slight bacterial wilt occurred recently, contained a single group, sequevar 15. The distribution of sequevars was associated with elevation. Sequevar 15 was over-represented in lowland elevations, while sequevar 54 and the new/unknown one were only found in areas of moderate to high elevations. This finding suggested that the phylotype I strains infecting tobacco were diverse in China and regional integrated control strategies should be considered.

Kosinostatin (KST), an antitumor antibiotic, features a pyrrolopyrrole moiety spirally jointed to a five-membered ring of an anthraquinone framework glycosylated with a γ-branched octose. By a combination of in silico analysis, genetic characterization, biochemical assay, and precursor feeding experiments, a biosynthetic pathway for KST was proposed, which revealed (1) the pyrrolopyrrole moiety originates from nicotinic acid and ribose, (2) the bicyclic amidine is constructed by a process similar to the tryptophan biosynthetic pathway, and (3) a discrete adenylation enzyme and a peptidyl carrier protein (PCP) are responsible for producing a PCP-tethered building block parallel to type II polyketide synthase (PKS) rather than for the PKS priming step by providing the starter unit. These findings provide an opportunity to further explore the inexplicable enzymatic logic that governs the formation of pyrrolopyrrole moiety and the spirocyclic skeleton.

Microarray analysis of toxicogenomic effects of CuO NPs on Arabidopsis thaliana was conducted. Arabidopsis growth was significantly inhibited by CuO NPs (10 and 20 mg/L). CuO NPs (10 and 20 mg/L) caused significant root damage after short-time (0-2 h) exposure while their corresponding Cu(2+) ions (0.80 and 1.35 mg/L) did not show any root damage. After longer exposure times (1 and 2 days), Cu(2+) ions induced obvious root damage, indicating that released Cu(2+) ions from CuO NPs contributed partial toxicity during CuO NPs exposure. After CuO NPs (10 mg/L) exposure for 2 h, reactive oxygen species (ROS) generation in root tips was much higher than that in the corresponding Cu(2+) ions (0.8 mg/L) treatment. The gene ontology categories identified from microarray analysis showed that CuO NPs (10 mg/L) caused 1658 differentially expressed genes (p < 0.01, fold change>3). Of these, 1035 and 623 genes were up-regulated and down-regulated, respectively. 47 genes among all the up-regulated genes were response to oxidative stress, in which 19 genes were also related to "response to abiotic stimulus" and 12 genes were involved in the phenylpropanoid biosynthesis of the KEGG metabolic pathway. The expression of all the selected genes (RHL41, MSRB7, BCB, PRXCA, and MC8) measured using quantitative RT-PCR was consistent with the microarray analysis. CuO NPs contributed much stronger up-regulation of oxidative stress-related genes than the corresponding Cu(2+) ions.

The green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), is an agricultural pest that seriously infests many crops worldwide. This study used electrical penetration graphs (EPGs) and life table parameters to estimate the sublethal effects of cyantraniliprole and imidacloprid on the feeding behavior and hormesis of M. persicae The sublethal concentrations (LC30) of cyantraniliprole and imidacloprid against adult M. persicae were 4.933 and 0.541 mg L(-1), respectively. The feeding data obtained from EPG analysis indicated that the count probes and number of short probes (<3 min) were significantly increased when aphids were exposed to LC30 of imidacloprid-treated plants. In addition, the phloem-feeding behavior of M persicae was significantly impaired on fed tobacco plants treated with cyantraniliprole and imidacloprid at LC30 Analysis of life table parameters indicated that the growth and reproduction of F1 generation aphids were significantly affected when initial adults were exposed to LC30 of cyantraniliprole and imidacloprid. The nymphal period, female longevity, total preoviposition period, and mean generation time were significantly prolonged when initial adults were exposed to LC30 of imidacloprid. By comparison, these parameters were prolonged but not significantly in the cyantraniliprole treatment. The fecundity and gross reproductive rate were significantly increased in the treated groups. Similarly, the net reproductive rate was greater in the treated group than the control group. Our results indicate that treatment with LC30 of imidacloprid and cyantraniliprole would lead to a hormetic response of M. persicae, with higher likelihood of occurrence when initial adults were exposed to LC30 of cyantraniliprole.

Ralstonia solanacearum , an agent of bacterial wilt, is a highly variable species with a broad host range and wide geographic distribution. As a species complex, it has extensive genetic diversity and its living environment is polymorphic like the lowland and the highland area, so more genomes are needed for studying population evolution and environment adaptation. In this paper, we reported the genome sequencing of R. solanacearum strain CQPS-1 isolated from wilted tobacco in Pengshui, Chongqing, China, a highland area with severely acidified soil and continuous cropping of tobacco more than 20 years. The comparative genomic analysis among different R. solanacearum strains was also performed. The completed genome size of CQPS-1 was 5.89 Mb and contained the chromosome (3.83 Mb) and the megaplasmid (2.06 Mb). A total of 5229 coding sequences were predicted (the chromosome and megaplasmid encoded 3573 and 1656 genes, respectively). A comparative analysis with eight strains from four phylotypes showed that there was some variation among the species, e.g., a large set of specific genes in CQPS-1. Type III secretion system gene cluster ( hrp gene cluster) was conserved in CQPS-1 compared with the reference strain GMI1000. In addition, most genes coding core type III effectors were also conserved with GMI1000, but significant gene variation was found in the gene ripAA : the identity compared with strain GMI1000 was 75% and the hrp II box promoter in the upstream had significantly mutated. This study provided a potential resource for further understanding of the relationship between variation of pathogenicity factors and adaptation to the host environment.

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