Purification of adult Drosophila melanogaster lipophorin and its role in hydrocarbon transport

Lipophorin was isolated from homogenized adult Drosophila melanogaster. It is stained by Sudan Black and has a native molecular mass of 640 kD and a density of 1.12 g/ml. It consists of two glycosylated apoproteins of 240 and 75 kDa. Gas chromatography and mass spectrometry showed that lipophorins isolated separately from virgin 3-day-old male and female flies were associated with specific hydrocarbons, and that these were the same hydrocarbons found in male and female cuticles, respectively. Moreover, a pool of internal hydrocarbons was demonstrated for the first time, with chain lengths similar to those of the cuticular pool. Studies on the fate of the hydrocarbons synthesized de novo after topical applications of radiolabelled fatty acid precursors showed a decrease of the internal pool of hydrocarbons with time, concomitant with an increase of the cuticular pool. These results suggest that hydrocarbons synthesized at an internal site, possibly in oenocytes, may be transported to the cuticle of the flies by lipophorin. © 1996 Wiley-Liss, Inc.     

Metabolic Enzyme Alterations and Astrocyte Dysfunction in a Murine Model of Alexander Disease With Severe Reactive Gliosis

Alexander disease (AxD) is a rare and fatal neurodegenerative disorder caused by mutations in the gene encoding glial fibrillary acidic protein (GFAP). In this report, a mouse model of AxD (GFAP^Tg;Gfap^+/R236H) was analyzed that contains a heterozygous R236H point mutation in murine Gfap as well as a transgene with a GFAP promoter to overexpress human GFAP. Using label-free quantitative proteomic comparisons of brain tissue from GFAP^Tg;Gfap^+/R236H versus wild-type mice confirmed upregulation of the glutathione metabolism pathway and indicated proteins were elevated in the peroxisome proliferator-activated receptor (PPAR) signaling pathway, which had not been reported previously in AxD. Relative protein-level differences were confirmed by a targeted proteomics assay, including proteins related to astrocytes and oligodendrocytes. Of particular interest was the decreased level of the oligodendrocyte protein, 2-hydroxyacylsphingosine 1-beta-galactosyltransferase (Ugt8), since Ugt8-deficient mice exhibit a phenotype similar to GFAP^Tg;Gfap^+/R236H mice (e.g., tremors, ataxia, hind-limb paralysis). In addition, decreased levels of myelin-associated proteins were found in the GFAP^Tg;Gfap^+/R236H mice, consistent with the role of Ugt8 in myelin synthesis. Fabp7 upregulation in GFAP^Tg;Gfap^+/R236H mice was also selected for further investigation due to its uncharacterized association to AxD, critical function in astrocyte proliferation, and functional ability to inhibit the anti-inflammatory PPAR signaling pathway in models of amyotrophic lateral sclerosis (ALS). Within Gfap⁺ astrocytes, Fabp7 was markedly increased in the hippocampus, a brain region subjected to extensive pathology and chronic reactive gliosis in GFAP^Tg;Gfap^+/R236H mice. Last, to determine whether the findings in GFAP^Tg;Gfap^+/R236H mice are present in the human condition, AxD patient and control samples were analyzed by Western blot, which indicated that Type I AxD patients have a significant fourfold upregulation of FABP7. However, immunohistochemistry analysis showed that UGT8 accumulates in AxD patient subpial brain regions where abundant amounts of Rosenthal fibers are located, which was not observed in the GFAP^Tg;Gfap^+/R236H mice.     

氨基酸和霉菌水提物对深层发酵桦褐孔菌菌丝体黄酮积累及其抗氧化活性的影响

黄酮类化合物是桦褐孔菌菌丝体中多酚类化合物的重要组成部分,也是该菌治疗众多疾病的有效成分之一。然而人工培养桦褐孔菌黄酮等酚类化合物积累甚少,导致药理活性的明显下降。为此,我们研究了3种氨基酸和4种霉菌水提物对深层发酵桦褐孔菌黄酮的积累及其抗氧化能力的影响。在所试验的3种氨基酸和4种霉菌水提物中,L-酪氨酸,黄曲霉和毛霉水提物能有效地增加该菌黄酮的积累。人工培养菌体中的黄酮至少由4种黄酮苷组成,苷元分别是槲皮素、柚皮素、山奈酚和异鼠李素。深层发酵菌丝体具有一定的抗氧化能力,并与总黄酮的含量呈正相关。由L-酪氨酸,黄曲霉和毛霉水提物调控生长的桦褐孔菌菌丝体,能有效地清除超氧阴离子、羟基自由基和DPPH自由基。     

Ecological influences on larval chironomid communities in shallow lakes: implications for palaeolimnological interpretations

1. To correctly interpret chironomid faunas for palaeoenvironmental reconstruction, it is essential that we improve our understanding of the relative influence of ecosystem variables, biotic as well as physicochemical, on chironomid larvae. To address this, we analysed the surface sediments from 39 shallow lakes (29 Norfolk, U.K., 10 Denmark) for chironomid head capsules, and 70 chironomid taxa (including Chaoborus) were identified. 2. The shallow lakes were selected over large environmental gradients of aquatic macrophytes, total phosphorus (TP) and fish communities. Redundancy analysis (RDA) identified two significant variables that explained chironomid distribution: macrophyte species richness (P < 0.001) and TP (P < 0.005). Generalised linear models (GLM) identified specific taxa that had significant relationships with both these variables. Macrophyte percentage volume infested (PVI) and species richness were significant in classifying the lake types based on chironomid communities under twinspan analysis, although other factors, notably nutrient concentrations and fish communities, were also important, illustrating the complexities of classifying shallow lake ecosystems. Lakes with plant species richness >10 all had relatively diverse (Hill’s N2) chironomid assemblages, and lakes with Hill’s N2 >10 all had TP <250 μg L⁻¹ and total fish densities <2 fish per m². 3. Plant density (PVI), and perhaps more importantly species richness, were primary controls on the distribution of chironomid communities within these lakes. This clearly has implications for palaeoenvironmental reconstructions using zoobenthos remains (i.e. chironomids) and suggests that they could be used to track changes in benthic/pelagic production and could be used as indicators of changing macrophyte habitat. 4. Measuring key biological gradients, in addition to physicochemical gradients, allowed the major controls on chironomid distribution to be assessed more directly, in terms of plant substrate, food availability, competition and predation pressure, rather than implying indirect mechanisms through relationships with nutrients. Many of these variables, notably macrophyte abundance and species richness, are not routinely measured in such studies, despite their importance in determining zoobenthos in temperate shallow lakes. 5. When physical, chemical and ecological gradients are considered, as is often the case with palaeo‐reconstructions rather than training sets chosen to maximise one gradient, complex relationships exist, and attempting to reconstruct a single trophic variable quantitatively may not be appropriate or reliable.     

n-Alkane uptake and utilisation by Streptomyces strains

Streptomyces strains isolated from the Kuwait Burgan oil field were defined as S. griseoflavus, S. parvus, and S. plicatus utilised n-hexadecane, n-octadecane (purified fractions of mineral oil), kerosene, and crude oil as sole carbon and energy sources. The strains were incubated with n-alkanes and increase of the fatty acid content with chain length equivalent to the employed n-alkanes was observed. Signal transducing GTP-binding proteins (GBPs) play an important role in n-alkane uptake in streptomycetes. Specific activators of GBPs increased the uptake of hydrocarbons. Using the hydrophobic fluorescent dye diphenylhexatrien (DPH) as a probe, it was found that the microviscosity of the hydrophobic inner region of the cellular membrane is significantly lower in hydrocarbon utilisers than in non-utilisers. This difference probably reflects differences in the fatty acid composition of the strains. When cultures were grown in n-alkane containing media, electron microscopy revealed that the hydrocarbon utilisers showed less-electron dense areas as inclusions in the cytoplasm. Soil samples inoculated with Streptomyces strains eliminated hydrocarbons much faster than those not containing these strains, serving as control. When inorganic medium was supplied with n-hexadecane-1-¹⁴C as sole carbon and energy source, radioactive CO₂ was detected. Since streptomycetes have not been used until now for oil elimination, though they are known as abundant soil bacteria tolerating extreme conditions, their possible use for bioremediation of hydrocarbon contaminated soils is discussed.     

Typical metabolic traits of two Oenococcus oeni strains isolated from Valpolicella wines

AIMS: Physiological comparison of two indigenous Oenococcus oeni strains, U1 and F3 isolated in the same area (Valpolicella, Italy) in order to select a performant starter for MLF in wine. METHODS AND RESULTS: Growth rate, sugar and malate metabolism in FT80 media at pH 5.3 and 3.5 were analysed. The amount of total protein synthesized and the level of expression of the small Hsp Lo18 were evaluated by radiolabelling and immunodetection experiments after heat (42 degrees C), acid (pH 3.5) and ethanol (12% v/v) stresses. Strain U1 showed significantly lower specific growth rate and growth yield in acid conditions than strain F3. However, strain U1 had a higher malate consumption capacity at pH 3.5 than strain F3, in relation with an higher malolactic activity determined on whole cells. Strain U1 exhibited about half the total protein synthesis level than strain F3, but both strains expressed Lo18 similarly. Evaluation of malolactic fermentation (MLF) performance by microvinification trials was carried out. Strain U1 was able to complete MLF, whereas strain F3 degraded malic acid partially when inoculated in Amarone wine. CONCLUSIONS: Considering its performances in microvinifications experiments, strain U1 could be a good candidate for malolactic starter as an alternative to deficient commercial starters.     

Temporal and spatial variation of forest biomass in relation to stand dynamics in a mature,lowland tropical rainforest,Malaysia

To clarify consistency in the size of carbon pool of a lowland tropical rainforest, we calculated changes in above-ground biomass in the Pasoh Forest Reserve, Peninsular Malaysia. We estimated the total above-ground biomass of a mature stand using tree census data obtained in a 6-ha plot every 2years from 1994 to 1998. The total above-ground biomass decreased consistently from 1994 (431Mgha^–1) to 1998 (403Mgha^–1) (1Mg=10³ kg). These are much lower than that in 1973 for a 0.2ha portion of the same area, suggesting that the the total above-ground biomass reduction might have been consistent in recent decades. This trend contrasted with a major trend for neotropical forests. During 1994–1998, the forest gained 23.0 and 0.88Mgha^–1 of the total above-ground biomass by tree growth and recruitment, respectively, and lost 51.9Mgha^–1 by mortality. Overall, the biomass decreased by 28.4Mgha^–1 (i.e. 7.10Mgha^–1·year^–1), which is almost equivalent to losing a 76-cm-diameter living tree per hectare per year. Analysis of positive and negative components of biomass change revealed that deaths of large trees dominated the total above-ground biomass decrease. The forest biomass also varied spatially, with the total above-ground biomass density ranging 212–655Mgha^–1 on a 0.2-ha basis (n= 30 subplots, 1998) and 365–440Mgha^–1 on a 1ha basis. A large decrease of the total above-ground biomass density (>50Mg per ha per 2years) in several 0.2-ha subplots contributed to the overall decrease in the 6-ha total above-ground biomass. In the present study, we discuss the association between forest dynamics and biomass fluctuation, and the implication for carbon cycling in mature forests with emphasis on forest monitoring and assessments of soil and decomposition systems.     

Allocation of energy use in petroleum refineries to petroleum products

Aim, Scope, and Background  Studies to evaluate the energy and emission impacts of vehicle/fuel systems have to address allocation of the energy use and emissions associated with petroleum refineries to various petroleum products because refineries produce multiple products. The allocation is needed in evaluating energy and emission effects of individual transportation fuels. Allocation methods used so far for petroleum-based fuels (e.g., gasoline, diesel, and liquefied petroleum gas [LPG]) are based primarily on mass, energy content, or market value shares of individual fuels from a given refinery. The aggregate approach at the refinery level is unable to account for the energy use and emission differences associated with producing individual fuels at the next sub-level: individual refining processes within a refinery. The approach ignores the fact that different refinery products go through different processes within a refinery. Allocation at the subprocess level (i.e., the refining process level) instead of at the aggregate process level (i.e., the refinery level) is advocated by the International Standard Organization. In this study, we seek a means of allocating total refinery energy use among various refinery products at the level of individual refinery processes. Main Features  We present a petroleum refinery-process-based approach to allocating energy use in a petroleum refinery to petroleum refinery products according to mass, energy content, and market value share of final and intermediate petroleum products as they flow through refining processes within a refinery. The approach is based on energy and mass balance among refining processes within a petroleum refinery. By using published energy and mass balance data for a simplified U.S. refinery, we developed a methodology and used it to allocate total energy use within a refinery to various petroleum products. The approach accounts for energy use during individual refining processes by tracking product stream mass and energy use within a refinery. The energy use associated with an individual refining process is then distributed to product streams by using the mass, energy content, or market value share of each product stream as the weighting factors. Results  The results from this study reveal that product-specific energy use based on the refinery process-level allocation differs considerably from that based on the refinery-level allocation. We calculated well-to-pump total energy use and greenhouse gas (GHG) emissions for gasoline, diesel, LPG, and naphtha with the refinery process-based allocation approach. For gasoline, the efficiency estimated from the refinery-level allocation underestimates gasoline energy use, relative to the process-level based gasoline efficiency. For diesel fuel, the well-to-pump energy use for the process-level allocations with the mass- and energy-content-based weighting factors is smaller than that predicted with the refinery-level allocations. However, the process-level allocation with the market-value-based weighting factors has results very close to those obtained by using the refinery-level allocations. For LPG, the refinery-level allocation significantly overestimates LPG energy use. For naphtha, the refinery-level allocation overestimates naphtha energy use. The GHG emission patterns for each of the fuels are similar to those of energy use. Conclusions  We presented a refining-process-level-based method that can be used to allocate energy use of individual refining processes to refinery products. The process-level-based method captures process-dependent characteristics of fuel production within a petroleum refinery. The method starts with the mass and energy flow chart of a refinery, tracks energy use by individual refining processes, and distributes energy use of a given refining process to products from the process. In allocating energy use to refinery products, the allocation method could rely on product mass, product energy contents, or product market values as weighting factors. While the mass- and energy-content-based allocation methods provide an engineering perspective of energy allocation within a refinery, the market-value-based allocation method provides an economic perspective. The results from this study show that energy allocations at the aggregate refinery level and at the refining process level could make a difference in evaluating the energy use and emissions associated with individual petroleum products. Furthermore, for the refining-process-level allocation method, use of mass — energy content- or market value share-based weighting factors could lead to different results for diesel fuels, LPG, and naphtha. We suggest that, when possible, energy use allocations should be made at the lowest subprocess level — a confirmation of the recommendation by the International Standard Organization for life cycle analyses. Outlook  The allocation of energy use in petroleum refineries at the refining process level in this study follows the recommendation of ISO 14041 that allocations should be accomplished at the subprocess level when possible. We developed a method in this study that can be readily adapted for refineries in which process-level energy and mass balance data are available. The process-level allocation helps reveal some additional energy and emission burdens associated with certain refinery products that are otherwise overlooked with the refinery-level allocation. When possible, process-level allocation should be used in life-cycle analyses.