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991.
Enrichment and identification of bacteria capable of reducing chemical oxygen demand of anaerobically treated molasses spent wash 总被引:2,自引:0,他引:2
AIMS: The aim of this study was to isolate and identify bacterial strains capable of using recalcitrant compounds of molasses spent wash as sole carbon source from the soils of abandoned sites of distillery effluent discharge and characterize their ability of reducing the chemical oxygen demand (COD) of the spent wash. METHODS AND RESULTS: The isolates were grouped into six haplotypes by amplified ribosomal DNA restriction analysis (ARDRA) and BOX-PCR. The phylogenetic position of the representatives of the six main haplotypes strains was determined by 16S rDNA sequencing. They showed maximum similarity to six genera viz. Pseudomonas, Enterobacter, Stenotrophomonas, Aeromonas, Acinetobacter and Klebsiella. The extent of COD (44%) reduced collectively by the six strains was equal to that reduced individually by Aeromonas, Acinetobacter, Pseudomonas and Enterobacter. With spent wash as sole carbon source, the COD reducing strains grew faster at 37 degrees C than 30 degrees C. CONCLUSIONS: Bacterial strains capable of degrading some of the recalcitrant compounds of anaerobically digested molasses spent wash can be isolated from the soils of abandoned sites of distillery effluent discharge. Biostimulation of these bacteria, which can degrade 44% of the carbon compounds of anaerobically digested molasses spent wash can be achieved by nitrogen fertilization and relatively higher temperature. SIGNIFICANCE AND IMPACT OF THE STUDY: Supplementation of nitrogen source and controlling the temperature can be used in evolving strategies for in situ bioremediation of anaerobically digested spent wash from distilleries. 相似文献
992.
Dimension reduction strategies for analyzing global gene expression data with a response 总被引:5,自引:0,他引:5
The analysis of global gene expression data from microarrays is breaking new ground in genetics research, while confronting modelers and statisticians with many critical issues. In this paper, we consider data sets in which a categorical or continuous response is recorded, along with gene expression, on a given number of experimental samples. Data of this type are usually employed to create a prediction mechanism for the response based on gene expression, and to identify a subset of relevant genes. This defines a regression setting characterized by a dramatic under-resolution with respect to the predictors (genes), whose number exceeds by orders of magnitude the number of available observations (samples). We present a dimension reduction strategy that, under appropriate assumptions, allows us to restrict attention to a few linear combinations of the original expression profiles, and thus to overcome under-resolution. These linear combinations can then be used to build and validate a regression model with standard techniques. Moreover, they can be used to rank original predictors, and ultimately to select a subset of them through comparison with a background 'chance scenario' based on a number of independent randomizations. We apply this strategy to publicly available data on leukemia classification. 相似文献
993.
Schoefs B 《Photosynthesis research》2001,70(3):257-271
994.
E. coli methionine sulfoxide reductase with a truncated N terminus or C terminus, or both, retains the ability to reduce methionine sulfoxide 下载免费PDF全文
Boschi-Muller S Azza S Branlant G 《Protein science : a publication of the Protein Society》2001,10(11):2272-2279
The monomeric peptide methionine sulfoxide reductase (MsrA) catalyzes the irreversible thioredoxin-dependent reduction of methionine sulfoxide. The crystal structure of MsrAs from Escherichia coli and Bos taurus can be described as a central core of about 140 amino acids that contains the active site. The core is wrapped by two long N- and C-terminal extended chains. The catalytic mechanism of the E. coli enzyme has been recently postulated to take place through formation of a sulfenic acid intermediate, followed by reduction of the intermediate via intrathiol-disulfide exchanges and thioredoxin oxidation. In the present work, truncated MsrAs at the N- or C-terminal end or at both were produced as folded entities. All forms are able to reduce methionine sulfoxide in the presence of dithiothreitol. However, only the N-terminal truncated form, which possesses the two cysteines located at the C-terminus, reduces the sulfenic acid intermediate in a thioredoxin-dependent manner. The wild type displays a ping-pong mechanism with either thioredoxin or dithiothreitol as reductant. Kinetic saturation is only observed with thioredoxin with a low K(M) value of 10 microM. Thus, thioredoxin is likely the reductant in vivo. Truncations do not significantly modify the kinetic properties, except for the double truncated form, which displays a 17-fold decrease in k(cat)/K(MetSO). Alternative mechanisms for sulfenic acid reduction are also presented based on analysis of available MsrA sequences. 相似文献
995.
Salinity is a major yield-reducing factor in coastal and arid, irrigated rice production systems. Salt tolerance is a major
breeding objective. Three rice cultivars with different levels of salt tolerance were studied in the field for growth, sodium
uptake, leaf chlorophyll content, specific leaf area (SLA), sodium concentration and leaf CO2 exchange rates (CER) at photosynthetic active radiation (PAR)-saturation. Plants were grown in Ndiaye, Senegal, at a research
station of the West Africa Rice Development Association (WARDA), during the hot dry season (HDS) and the wet season (WS) 1994
under irrigation with fresh or saline water (flood water electrical conductivity = 3.5 mS cm-1). Relative leaf chlorophyll content (SPAD method) and root, stem, leaf blade and panicle dry weight were measured at weekly
intervals throughout both seasons. Specific leaf area was measured on eight dates, and CER and leaf sodium content were measured
at mid-season on the first (topmost) and second leaf. Salinity reduced yields to nearly zero and dry-matter accumulation by
90% for the susceptible cultivar in the HDS, but increased leaf chlorophyll content and CER at PAR- saturation. The increase
in CER, which was also observed in the other cultivars and seasons, was explained by a combination of two hypotheses: leaf
chlorophyll content was limited by the available N resources in controls, but not in salt-stressed plants; and the sodium
concentrations were not high enough to cause early leaf senescence and chlorophyll degradation. The growth reductions were
attributed to loss of assimilates (mechanisms unknown) that must have occurred after export from the sites of assimilation.
The apparent, recurrent losses of assimilates, which were between 8% and 49% according to simulation with the crop model for
potential yields in irrigated rice, ORYZA S, might be partly due to root decomposition and exudation. Possibly more importantly,
energy-consuming processes, such as osmoregulation, interception of sodium and potassium from the transpiration stream in
leaf sheaths and their subsequent storage, drained the assimilate supply.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
996.
Sun Jae Yoo Jacques Meyer Catalina Achim James Peterson Michael P. Hendrich E. Münck 《Journal of biological inorganic chemistry》2000,5(4):475-487
Rubredoxins contain a mononuclear iron tetrahedrally coordinated by four cysteinyl sulfurs. We have studied the wild-type protein from Clostridium pasteurianum and two mutated forms, C9S and C42S, in the oxidized and reduced states, with Mössbauer, integer-spin EPR, and magnetic circular dichroism (MCD) spectroscopies. The Mössbauer spectra of the ferric C42S and C9S mutant forms yielded zero-field splittings, D=1.2?cm?1, that are about 40% smaller than the D-value of the wild-type protein. The 57Fe hyperfine coupling constants were found to be ca. 8% larger than those of the wild-type proteins. The present study also revealed that the ferric wild-type protein has δ=0.24±0.01?mm/s at 4.2?K rather than δ=0.32?mm/s as reported in the literature. The Mössbauer spectra of both dithionite-reduced mutant proteins revealed the presence of two ferrous forms, A and B. These forms have isomer shifts δ=0.79?mm/s at 4.2?K, consistent with tetrahedral Fe2+(Cys)3(O-R) coordination. The zero-field splittings of the two forms differ substantially; we found D=?7±1?cm?1, E/D=0.09 for form A and D=+6.2±1.3?cm?1, E/D=0.15 for form B. Form A exhibits a well-defined integer-spin EPR signal; from studies at X- and Q-band we obtained g z =2.08±0.01, which is the first measured g-value for any ferrous rubredoxin. It is known from X-ray crystallographic studies that ferric C42S rubredoxin is coordinated by a serine oxygen. We achieved 75% reduction of C42S rubredoxin by irradiating an oxidized sample at 77?K with synchrotron X-rays; the radiolytic reduction produced exclusively form A, suggesting that this form represents a serine-bound Fe2+ site. Studies in different buffers in the pH?6–9 range showed that the A:B ratios, but not the spectral parameters of A and B, are buffer dependent, but no systematic variation of the ratio of the two forms with pH was observed. The presence of glycerol (30–50% v/v) was found to favor the B form. Previous absorption and circular dichroism studies of reduced wild-type rubredoxin have suggested d-d bands at 7400, 6000, and 3700?cm?1. Our low-temperature MCD measurements place the two high-energy transitions at ca. 5900 and 6300?cm?1; a third d-d transition, if present, must occur with energy lower than 3300?cm?1. The mutant proteins have d-d transitions at slightly lower energy, namely 5730, 6100?cm?1 in form A and 5350, 6380?cm?1 in form B. 相似文献
997.
Modifications to reduce bycatch in prawn trawls: A review and framework for development 总被引:13,自引:0,他引:13
The incidental capture of non-target species fromprawn trawling has recently attracted worldwide attention. Primarily, concerns arisefrom the perception that prawn trawls catch anddiscard large numbers of juveniles of species that,when larger, are targeted in other commercial andrecreational fisheries. While several managementoptions are available, the majority of fisheries inthe world have attempted to address this issue throughphysical modifications to trawls, designed to improveselectivity. The types of modifications used reflectfishery-specific characteristics; however, mostcan be broadly classified into twocategories, including: (1) those that separate speciesby differences in behaviour; and (2) those thatmechanically exclude unwanted organisms according totheir size. In the present paper, I provide achronological review of publications in the primaryliterature that describe experiments examiningmodifications within these categories. This reviewshows that inherent variabilities among differentfisheries greatly influence the types of designs thatneed to be applied and although some designs have thepotential for application across different fisheries,significant modification and re-evaluation are oftenrequired. By collating information from previousstudies, I also propose a framework encompassingthe various stages involved in developing and applyingsuccessful modifications in prawn-trawl fisheries. The key stages identified include: (1) quantificationof bycatches and accumulation of fishery-relatedinformation; (2) examination and re-evaluation ofmodifications; (3) assessment of damage inflicted onescaping individuals; and (4) promotion of recommendeddesigns. 相似文献
998.
Effects of early plant growth regulator treatments on flavonoid levels in grapefruit 总被引:1,自引:0,他引:1
Mark A. Berhow 《Plant Growth Regulation》2000,30(3):225-232
Early foliar spray treatments containing gibberellic acid(GA3) significantly lower the concentration ofthe bitter flavonoid naringin in fruit tissues. Sprayscontaining a surfactant and different levels ofGA3 (5, 50, 100, and 500 ppm) or abscisic acid(ABA) (5, 25, and 50 ppm) were applied to young,developing fruit on mature grapefruit (Citrusparadisi) trees during the period from April to June,beginning just after fruit set. The fruit were allowedto mature and were harvested early the following year.Harvested fruit were evaluated for weight, juicecharacteristics, and flavonoid concentrations.GA3 application resulted in larger mature fruit,which yielded juice with the same soluble solids valueas juice from control fruit, but with slightly loweracid percentages and lower concentrations of naringin.ABA treatment had little effect on juice solublesolids, acid content and naringin content except atthe highest concentration of 50 ppm, which lowerednaringin levels slightly in juice. 相似文献
999.
Ayhan S. Demir Haluk Hamamci Fatos Doganel Emine Ozgul 《Journal of Molecular Catalysis .B, Enzymatic》2000,9(4-6):157-161
The synthesis of (1S,2R)-1-amino-2-indanol, a key component of HIV protease inhibitor is accomplished in four steps starting from indanone efficiently and with high levels of diastereo- and enantioselectivity. The starting material is converted into 2-acetoxy-1-indanone involving Manganese (III) acetate oxidation . The 2-acetoxyketone is hydrolyzed to 2-hydroxy-1-indanone enantioselectively using Rhizopus oryzae. Selective reduction of 2-hydroxyoxime derivative, derived from the 2-hydroxyketone, gives the amino alcohol up to 98% diastereo- and enantioselectivity. 相似文献
1000.
Renad I. Zhdanov 《Steroids》2009,74(9):723-724
The “Torgov reaction” opened an original pathway for the total chemical synthesis of steroid hormones, which is still used for the large-scale industrial production of steroid hormones at factories of Schering AG in Berlin, Germany. 相似文献