Identification and analysis of a Scophthalmus maximus ferritin that is regulated at transcription level by oxidative stress and bacterial infection

Ferritins are conserved Iron storage proteins that exist in most living organisms and play an essential role in Iron homeostasis. In this study, we reported the identification and analysis a ferritin M subunit, SmFerM, from turbot Scophthalmus maximus. The full length cDNA of SmFerM contains a 5'-untranslated region (UTR) of 232 bp, an open reading frame (ORF) of 531 bp, and a 3'-UTR of 196 bp The ORF encodes a putative protein of 176 amino acids, which shares extensive sequence identities with the M terrains of several fish species. In silico analysis identified in SmFerM both the ferroxidase center of mammalian H ferritins and the iron nucleation site of mammalian L ferritins. Quantitative real time reverse transcriptase-PCR analysis indicated that SmFerM expression was highest in muscle and lowest in heart and responded positively to experimental challenges with bacterial pathogens and poly(I center dot C) Exposure of cultured turbot hepatocytes to treatment of stress inducers (iron, copper, and H2O2) significantly upregulated the expression of SmFerM in a dose dependent manner. Iron chelating analysis showed that recombinant SmFerM purified from Escherichia coli exhibited apparent iron binding activity. These results suggest that SmFerM is a functional M ferritin and is likely to play a role in iron sequestration and protection against oxidative stress and microbial infection (C) 2010 Elsevier Inc All rights reserved

Close coupling between phytoplankton growth and microzooplankton grazing in the western South China Sea

We conducted 28 dilution experiments during August-September 2007 to investigate the coupling of growth and microzooplankton grazing rates among ultraphytoplankton populations and the phytoplankton community and their responses to habitat variability (open-ocean oligotrophy, eddy-induced upwelling, and the Mekong River plume) in the western South China Sea. At the community level, standing stocks, growth, and grazing rates were strongly and positively correlated, and were related to the higher abundance of larger phytoplankton cells (diatoms) at stations with elevated chlorophyll concentration. Phytoplankton growth rates were highest (> 2 d(-1)) within an eastward offshore jet at 13 degrees N and at a station influenced by the river plume. Among ultraphytoplankton populations, Prochlorococcus dominated the more oceanic and oligotrophic stations characterized by generally lower biomass and phytoplankton community growth, whereas Synechococcus became more important in mesotrophic areas (eddies, offshore jet, and river plume). The shift to Synechococcus dominance reflected, in part, its higher growth rates (0.87 +/- 0.45 d(-1)) compared to Prochlorococcus (0.65 +/- 0.29 d(-1)) or picophytoeukaryotes (0.54 +/- 0.50 d(-1)). However, close coupling of microbial mortality rates via common predators is seen to play a major role in driving the dominance transition as a replacement of Prochlorococcus, rather than an overprinting of its steady-state standing stock.

PCBs and its coupling with eco-environments in Southern Yellow Sea surface sediments

In this paper, the spatial distribution and source of the PCBs in surface sediments of the Southern Yellow Sea (SYS) and influencing factors, such as the sediment characteristics (components, relative proportions and total organic carbon contents), and hydrodynamic conditions were analyzed. PCB concentrations in the surface sediments ranged from 518-5848 pg/g, with average values of 1715 pg/g decreasing sharply compared to last year. In the study area, the PCB pollution level in the middle area was the highest, followed by that of the east coast and the west coast, respectively. Although the PCB level in the coastal areas was lower than that in the middle areas, it was proven in our study that the Yellow Sea obtained PCBs by virtue of river inputs. There was a positive and pertinent correlation between the clay proportion and PCB concentrations, and the increase of the PCB concentrations was directly proportional to the increase of TOC contents, with r = 0.61, but it was contrary to the sediment grain size. Consequently, the factors controlling PCB distribution had direct or indirect relationships with sediment grain size; moreover, the hydrodynamic conditions determined the sediment components and grain size. In conclusion, hydrodynamic conditions of the Yellow Sea were the most important influencing factors effecting the distribution of PCBs in the surface sediments of the SYS. (C) 2007 Elsevier Ltd. All rights reserved.

Influence of filtering and biodeposition by the cultured scallop Chlamys farreri on benthic-pelagic coupling in a eutrophic bay in China

In coastal ecosystems, suspension-cultured bivalve filter feeders may exert a strong impact on phytoplankton and other suspended particulate matter and induce strong pelagic-benthic coupling via intense filtering and biodeposition. We designed an in situ method to determine spatial variations in the filtering-biodeposition process by intensively suspension-cultured scallops Chlamys farreri in summer in a eutrophic bay (Sishili Bay, China), using cylindrical biodeposition traps directly suspended from longlines under ambient environmental conditions. Results showed that bivalve filtering-biodeposition could substantially enhance the deposition of total suspended material and the flux of C, N and P to the benthos, indicating that the suspended filter feeders could strongly enhance pelagic-benthic coupling and exert basin-scale impacts in the Sishili Bay ecosystem. The biodeposition rates of 1-yr-old scallops varied markedly among culture sites (33.8 to 133.0 mg dry material ind.(-1) d(-1)), and were positively correlated with seston concentrations. Mean C, N and P biodeposition rates were 4.00, 0.51, 0.11 mg ind.-1 d-1, respectively. The biodeposition rates of 2-yr-old scallops were almost double these values. Sedimentation rates at scallop culture sites averaged 2.46 times that at the reference site. Theoretically, the total water column of the bay could be filtered by the cultured scallops in 12 d, with daily seston removal amounting to 64%. This study indicated that filtering-biodeposition by suspension-cultured scallops could exert long-lasting top-down control on phytoplankton biomass and other suspended material in the Sishili Bay ecosystem. In coastal waters subject to anthropogenic N and P inputs, suspended bivalve aquaculture could be advantageous, not only economically, but also ecologically, by functioning as a biofilter and potentially mitigating eutrophication pressures. Compared with distribution-restricted wild bivalves, suspension-cultured bivalves in deeper coastal bays may be more efficient in processing seston on a basin scale.

Oxidative dehydrogenation of ethane to ethylene over LiCl/MnOx/PC catalysts

The catalytic stability of LiCl/MnOx/PC catalyst have been investigated, the deactivation mechanism was discussed. The experimental results show that ethane conversion decreases and ethylene selectivity keeps about 90% as reaction time increases. The main deactivation reasons of LiCl/MnOx/PC catalyst for oxidative dehydrogenation of ethane (ODHE) to ethylene are the transition of active species Mn2O3 to MnO species and the loss of arrive component Cl in catalyst. instead of ethane with FCC tailed-gas, the stability of LiCl/MnOx/PC catalyst has been largely improved.

Investigations on the promoting effect of metal oxides on La-V-O catalyst in propane oxidative dehydrogenation

The addition of reducible metal oxides as promoters shows a positive effect on the catalytic behavior of lanthanum vanadate (LaVO4). A C3H6 yield increase of 6.5% is observed at 500 degreesC on molybdenum-promoted LaVO4, which can be attributed to the change of the redox properties, the blocking of the strong oxidation sites of the catalysts and to an increase of the accessibility of the labile oxygen toward the reactant. The influence of the catalyst preparation method and of the Mo loading as well as the additional promoting effect of CO2 in the gas feed was also examined.

Oxidative dehydrogenation of ethane and propane over Mn-based catalysts

The catalytic performances of Mn-based catalysts have been investigated for the oxidative dehydrogenation of both ethane (ODE) and propane (ODP). The results show that a LiCl/MnOx/PC (Portland cement) catalyst has an excellent catalytic performance for oxidative dehydrogenation of both ethane and propane to ethylene and propylene, more than 60% alkanes conversion and more than 80% olefins selectivity could be achieved at 650 degrees C. In addition, the results indicate that Mn-based catalysts belong to p-type semiconductors, the electrical conductivity of which is the main factor in influencing the olefins selectivity. Lithium, chlorine and PC in the LiCl/MnOx/PC catalyst are all necessary components to keep the excellent catalytic performance at a low temperature.

Oxidative carbonylation of aniline over a polymer-supported palladium-copper catalyst

The polymer-supported bimetallic catalyst FVP-PdCl2-2CuCl(2) (PVP, poly(N-vinyl-2-pyrrolidone), obtained in situ by the addition of CuCl2 to an alcoholic solution of PVP-PdCl2, exhibits high selectivity and activity for the oxidative carbonylation of aniline with carbon monoxide and oxygen to ethyl N-phenylcarbamate in the presence of a base (NaOAc) under atmospheric pressure. The strong synergic effect of Pd-Cu gives rise to a clear increase in the selectivity and activity. (C) 2000 Elsevier Science B.V. All rights reserved.