Institutional Repository of South China Sea Institute of Oceanology, CAS
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HR38, an ortholog of NR4A family nuclear receptors, mediates 20-hydroxyecdysone regulation of carbohydrate metabolism during mosquito reproduction
No full textThe Aedes aegypti mosquito is the principal vector for many dangerous human viral diseases. Carbohydrate metabolism (CM) is essential for supplying the energy necessary for host seeking, blood digestion and rapid egg development of this vector insect. The steroid hormone 20-hydroxyecdysone (20E) and the ecdysone receptor (EcR) are important regulators of CM, coordinating it with female reproductive events. We report here that the NR4A nuclear receptor AHR38 plays a critical role in mediating these actions of 20E and EcR. AHR38 RNA interference (RNAi) depletion in female mosquitoes blocked the transcriptional activation of CM genes encoding phosphoglucomutase (PGM) and trehalose-6-phophate synthase (TPS); it caused an increase of glycogen accumulation and a decrease of the circulating sugar trehalose. This treatment also resulted in a dramatic reduction in fecundity. Considering that these phenotypes resulting from AHR38 RNAi depletion are similar to those of EcR RNAi, we investigated a possible connection between these transcription factors in CM regulation. EcR RNAi inhibits the AHR38 gene expression. Moreover, the 20E-induced EcR complex directly activates AHR38 by binding to the ecdysone response element (EcRE) in the upstream regulatory region of this gene. The present work has implicated AHR38 in the 20E-mediated control of CM and provided new insight into mechanisms of 20E regulation of metabolism during female mosquito reproduction
Synergistic antibacterial activity between penicillenols and antibiotics against methicillin-resistant Staphylococcus aureus
No full textPenicillenol A2 (isolated from deep-sea fungus Penicillium biourgeianum DFFSCS023) has good antibacterial activity against methicillin-sensitive Staphylococcus aureus and in combination with beta-lactam antibiotics it could significantly decrease methicillin-resistant Staphylococcus aureus (MRSA) survival, which provides a novel treatment consideration for MRSA-caused infections
The semi-synthesis, biological evaluation and docking analysis of the oxime, hydrazine and hydrazide derivatives of platensimycin
No full textA dozen oxime, hydrazine and hydrazide derivatives of platensimycin (PTM) analogues were synthesized, some of which showed strong antibacterial activities and were shown to be stable under the bioassay conditions. Docking analysis revealed that they have certain new interactions with beta-ketoacyl-[acyl carrier protein] synthase II (FabF), suggesting that Schiff base formation on its terpene scaffold is an effective strategy to diversify PTM structure
Personal care products in wild fish in two main Chinese rivers: Bioaccumulation potential and human health risks
No full textPersonal care products (PCPs) are widely applied in our daily life, however, little is known about their occurrence in wild fish. We investigated the bioaccumulation and potential risks of 24 PCPs in muscle and liver tissues of wild fish collected from two large rivers of Pearl and Yangtze Rivers in China. The results showed the detection of a total of 13 PCPs including 9 biocides, 2 synthetic musks and 2 benzotriazoles in at least one type of fish tissue from 12 fish species. The compounds with high detection frequencies (> 50%) in fish muscle or liver tissues were N, N-diethyl-3-methylbenzamide, carbendazim, climbazole, miconazole (MCZ), methylparaben, propylparaben, triclosan (TCS), tonalide, galaxolide (HHCB) and 5-methyl-1H-benzotriazole (5-TT). Among biocides, synthetic musks and benzotriazoles, TCS, HHCB and benzotriazole showed the maximum concentrations of 79.5 ng/g wet weight (ww), 299 ng/g ww and 3.14 ng/g ww, respectively, in muscle tissue, while MCZ, HHCB and 5-TT showed the maximum concentrations of 432 ng/g ww, 2619 ng/g ww and 54.5 ng/g ww, respectively, in liver tissue. The median values of logarithm of bioaccumulation factors (BAF) for the detected 13 PCPs were ranged 0.8-3.35 in muscle and 0.85-4.58 in liver. The log BAF values of the PCPs displayed good linear relationships with log K-ow and log D-ow (pH-dependent K-ow). The health hazard assessment of 10 detected PCPs in the muscle indicated no appreciable risk to human via consumption of the wild fish. (c) 2017 Elsevier B.V. All rights reserved
Nano-rod Ca-decorated sludge derived carbon for removal of phosphorus
No full textRecovering phosphorus (P) from waste streams takes the unique advantage in simultaneously addressing the crisis of eutrophication and the shortage of P resource. A novel calcium decorated sludge carbon (Ca-SC) was developed from dyeing industry wastewater treatment sludge by decorating calcium (Ca) to effectively adsorb phosphorus from solution. The X-ray diffraction (XRD) and Fourier transform infrared (FTIR) techniques were used to characterize the Ca-SCs, followed by isotherm and kinetic sorption experiments. A preferred design with CaCO3 to sludge mass ratio of 1:2 was found to have a sorption capacity of 116.82 mg/g for phosphorus. This work reveals the crucial role of well-dispersed nano-rod calcium on the Ca-SC surface for the sorption of phosphorus. Moreover, the decoration of nano-rod calcium was found to further promote the uptake of phosphorus through the formation of hydroxyl apatite (Ca-5(PO4)(3)(OH)). Thus, the development of decorated Ca-SC for sorption of phosphorus is very important in solving the P pollution and resource loss. (C) 2017 Elsevier Ltd. All rights reserved
Hygrocin C from marine-derived Streptomyces sp SCSGAA 0027 inhibits biofilm formation in Bacillus amyloliquefaciens SCSGAB0082 isolated from South China Sea gorgonian
No full textSeveral ansamycins have been reported to inhibit bacterial biofilm formation and accelerate the eradication of developed biofilms, but little is known about the effect of hygrocin C, an ansamycin, on bacterial biofilm formation. Here, hygrocin C was isolated from the marine-derived Streptomyces sp. SCSGAA 0027 and reported for the first time to be capable of inhibiting the biofilm formation of Staphylococcus aureus and Bacillus amyloliquefaciens SCSGAB0082 with the production of anti-microbial lipopeptides from South China Sea gorgonian Subergorgia suberosa at concentrations of less than minimum inhibitory concentrations. Moreover, hygrocin C also promoted the eradication of developed biofilms, affected the biofilm architecture, and lowered the extracellular polymeric matrix formation, cell motility, and surface hydrophobicity in B. amyloliquefaciens, which was in accordance with the inhibition of biofilm formation. Furthermore, transcriptome analysis revealed that hygrocin C altered the transcripts of several genes associated with bacterial chemotaxis and flagellar, two-component system and the synthesis of arginine and histidine, which are important for bacterial biofilm formation. In conclusion, hygrocin C could be used as a potential biofilm inhibitor against S. aureus and B. amyloliquefaciens. But further genetic investigations are needed to provide more details for elucidation of the molecular mechanisms responsible for the effects of hygrocin C on B. amyloliquefaciens biofilm formation
Community structure and biovolume size spectra of mesozooplankton in the Pearl River estuary
No full textThe Pearl River estuary is the second largest estuary in China. This study reported the species composition and size structure of mesozooplankton in the upper and lower Pearl River estuary in the dry and wet seasons. The normalized biovolume size spectrum of mesozooplankton was constructed to analyze the trophic structure of the community. Copepods were the numerically predominant mesozooplankton group at all sampling stations. However, when converted into biovolume, medusae were dominant in the upper estuary in the dry season and Chaetognatha were dominant in the lower estuary in the wet season. There were apparent seasonal and spatial variations in the normalized biovolume size spectrum characteristics in the Pearl River estuary. In the dry season, the average fitted regression line of the normalized biovolume size spectrum had a slope of -1.02 in the upper estuary and -0.88 in the lower estuary. In the wet season, the average fitted regression line of the normalized biovolume size spectrum had a slope of -0.32 in the lower estuary, and no significant regression of the normalized biovolume size spectrum was found in the upper estuary. It is suggested that the mesozooplankton community was unstable in the upper estuary due to the strong freshwater perturbation in the wet season. The size diversity and normalized biovolume size spectrum slope indicated that the strength of top-down control and trophic efficiency was highest in the lower estuary in the wet season
Survival and growth of reciprocal crosses between two stocks of the Hong Kong oyster Crassostrea hongkongensis (Lam & Morton, 2003) in southern China
No full textThe Hong Kong oyster, Crassostrea hongkongensis, is one of the most economically important and well-known oyster species in southern China. To explore the possibility of improving the performance of the Hong Kong oyster, complete diallel crosses between two oyster stocks, the Zhuhai stock (Z: fast growth line F4) and the Maowei Sea stock (M: resistant line F3), were conducted using pooled gametes. Three replicates, each consisting of two pure stocks (ZZ and MM) and two reciprocal crosses (ZM and MZ), were successfully generated. High fertilization rate and hatching level were observed among all the experimental groups, suggesting that there was no sperm-egg recognition barrier between geographic populations. Reciprocal crosses had higher survival rate compared to the pure stock crosses and the rate of survival increased with progeny growth. Growth heterosis became obvious both in larval and adult stages, and was primarily influenced by the egg origin and mating strategy at the larval stage. Also, the phenotypic traits of all progeny differed amongst the culture sites, suggesting a significant environmental effect. The Zhuhai site was more suitable for oyster aquaculture than the Maowei Sea site. Thus, our results demonstrated that crossbreeding between Zhuhai and Maowei Sea stocks of Hong Kong oyster to produce superior heterosis represents a promising means to improve the fishery yield of this species in southern China
Effect of wind speed on the size distribution of gel particles in the sea surface microlayer: insights from a wind-wave channel experiment
No full textGel particles, such as transparent exopolymer particles (TEP) and Coomassie stainable particles (CSP), are important organic components in the sea surface microlayer (SML). Here, we present results on the effect of different wind speeds on the accumulation and size distribution of TEP and CSP during a wind wave channel experiment in the Aeolotron. Total areas of TEP (TEPSML) and CSP (CSPSML) in the surface microlayer were exponentially related to wind speed. At wind speeds < 6 m s(-1), accumulation of TEPSML and CSPSML occurred, decreasing at wind speeds of > 8 ms(-1). Wind speeds > 8 m s(-1) also significantly altered the size distribution of TEPSML in the 2-16 mu m size range towards smaller sizes. The response of the CSPSML size distribution to wind speed varied through time depending on the biogenic source of gels. Wind speeds > 8 m s(-1) decreased the slope of CSPSML size distribution significantly in the absence of autotrophic growth. For the slopes of TEP and CSP size distribution in the bulk water, no significant difference was observed between high and low wind speeds. Changes in spectral slopes between high and low wind speed were higher for TEPSML than for CSPSML, indicating that the impact of wind speed on size distribution of gel particles in the SML may be more pronounced for TEP than for CSP, and that CSPSML are less prone to aggregation during the low wind speeds. Addition of an E. huxleyi culture resulted in a higher contribution of submicron gels (0.4-1 mu m) in the SML at higher wind speed (> 6 m s(-1)), indicating that phytoplankton growth may potentially support the emission of submicron gels with sea spray aerosol
Variations in High-frequency Oscillations of Tropical Cyclones over the Western North Pacific
No full textVariations in the high-frequency oscillations of tropical cyclones (TCs) over the western North Pacific (WNP) are studied in numerical model simulations. Power spectrum analysis of maximum wind speeds at 10 m (MWS10) from an ensemble of 15 simulated TCs shows that oscillations are significant for all TCs. The magnitudes of oscillations in MWS10 are similar in the WNP and South China Sea (SCS); however, the mean of the averaged significant periods in the SCS (1.93 h) is shorter than that in the open water of the WNP (2.83 h). The shorter period in the SCS is examined through an ensemble of simulations, and a case simulation as well as a sensitivity experiment in which the continent is replaced by ocean for Typhoon Hagupit (2008). The analysis of the convergence efficiency within the boundary layer suggests that the shorter periods in the SCS are possibly due to the stronger terrain effect, which intensifies convergence through greater friction. The enhanced convergence strengthens the disturbance of the gradient and thermal wind balances, and then contributes to the shorter oscillation periods in the SCS