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61.
两种钙藻热解产出的气态和液态烃类 总被引:2,自引:0,他引:2
在200℃至400℃高温和还原条件下分别对仙掌藻和乳节藻两种钙质藻类进行热模拟降解实验,分离获得气态和液态烃类化合物。随着热解温度升高,两种钙藻产烃气量明显上升,其中甲烷与乙烷气的增加最多,同时两种钙藻产出的乙烷与乙烯比值都有规律地增加,但仙掌藻产烃气量高于乳节藻。这表明钙质藻类可能是天然气的一种重要母质来源。虽然这两种钙藻随温度增加热解产出的可溶有机质及族组分的变化规律不明显,但它们的正烷烃分布特征具有相类似的变化。未经热解时它们都以C17为主峰的低碳数正烷烃占优势;当热解温度从200℃增加到400℃时,它们都又表现出以C25或C23为主峰的较高碳数正烷烃占优势的分布特征。这与富含钙藻化石的沉积岩样品中正烷烃的分布特征相一致,说明C25或C23为主峰的较高碳数正烷烃占优势的分布特征可能是钙藻热解有机质的一种判识标志. 相似文献
62.
Ethylbenzene degradation by Pseudomonas fluorescens strain CA-4 总被引:2,自引:0,他引:2
David M. Corkery Kevin E. O'Connor Catherine M. Buckley Alan D.W. Dobson 《FEMS microbiology letters》1994,124(1):23-27
Abstract Pseudomonas fluorescens strain CA-4 is a bioreactor isolate capable of ethylbenzene degradation. Transposon mutagenesis and enzyme assays have been performed which allow us to propose the ethylbenzene degradative pathway in operation in this strain. Ethylbenzene is initially converted to 2-phenylethanol. This is degraded to phenylacetaldehyde and then to phenylacetic acid. The major inducer of the pathway is ethylbenzene itself. The pathway is regulated by the presence of non-aromatic carbon sources. Oxidation of ethylbenzene is repressed by glutamate, but not by citrate or glucose. A clone from a chromosomal library has been found to complement a mutant deficient in the ability to convert ethylbenzene to 2-phenylethanol. 相似文献
63.
Purification and characterization of a thiol-protease induced during senescence of unpollinated ovaries of Pisum sativum 总被引:1,自引:0,他引:1
A senescence-specific protease has been purified from senescent unpollinated ovaries of Pisum sativum L. cv. Alaska by acidic extraction. (NH4 )2 SO4 fractionation, ion exchange chromatography on CM-Sephadex, and affinity chromatography on ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco)-Sepharose. Characterization of the purified protease indicated that it is a thiol-endoprotease (EC 3. 4. 22 class) active over a wide pH range. Purified antibodies against this protease inhibit the degradation of Rubisco in autodigested extracts of senescent ovaries, suggesting that Rubisco might be a substrate for the protease in senescent pea ovaries. The relative levels of the protease were determined by an enzyme-linked immunosorbent assay (ELISA) along the processes of ovary senescence and gibberellic acid (GA)-induced fruit development, indicating its induction at the beginning of senescence and the suppression of its synthesis by GA treatment. 相似文献
64.
Photosynthesis has been determined with mutants of Anacystis which form different amounts of carotenoids. With these cultures a highly significant correlation between photosynthetic oxygen evolution and the amounts of synthesized carotenoids was observed. In addition, the influence of carotenoids on light-dependent degradation of thylakoid proteins was investigated with Scenedesmus cultures grown in darkness in the presence of norflurazon, an inhibitor of carotenoid biosynthesis. Pre-illumination of cells resulted in decrease of photosynthetic activity accompanied by loss of the D1 protein. This effect is dependent on the length of illumination, and the light intensity, and increased when carotenoid content was lowered during previous growth of the norflurazon-treated cultures.Abbreviations BSA
bovine serum albumin
- D1
32 kDa QB-binding protein
- EDTA
ethylenediaminetetraacetic acid
- LHCII
light-harvesting complex II
- PMSF
phenylmethylsulfonyl fluoride
- PS
photosystem
- tricine
N-[tris(hydroxymethyl)methyl] glycine 相似文献
65.
When fenugreek (Trigonella foenum-graecum L.) endosperms plus testa (endosperms), which had been isolated from 5-h-imbibed seeds, were incubated for at least 2 h under germination conditions, they leaked substances which, like exogenous abscisic acid (ABA), inhibited the production of fenugreek endosperm -galactosidase. However, unlike ABA, 8 h treatment with these inhibitors had no effect on fenugreek endosperms which had been isolated from 15-h-imbibed seeds and leached for 2 h. This indicated that either their inhibitory action was on processes which were related to the production of -galactosidase and had been completed by this time, or that there might be factors present which inactivate these inhibitors. It was also concluded that the action of the endosperm leachate could not be attributed to the presence of ABA. The activity of the leachate decreased when it originated from endosperms imbibed for periods longer than 25 h and thin-layer chromatography (TLC) of extracts from these endosperms showed decreased contents of the leachable inhibitors as imbibition proceeded. From the seed leachate, which had a TLC pattern and inhibitory action similar to that of the endosperm, were isolated three substances which, when applied to endosperms, inhibited the production of -galactosidase activity. According to their chromatographic behaviour and their reaction with specific reagents, there are strong indications that these substances are saponins. These diffusible saponin-like substances were located in both endosperm and perisperm and their physiological role is discussed.Abbreviations ABA
abscisic acid
- PEG
polyethylenglycol
- TLC
thin-layer chromatography
We wish to thank the Alexander S. Onasis Public Benefit Foundation for a grant to K.Z. and Dr. J.S.G. Reid (University of Stirling, Scotland) for a kind gift of fenugreek seeds. 相似文献
66.
Marc J. E. C. van der Maarel Peter Quist Lubbert Dijkhuizen Theo A. Hansen 《Archives of microbiology》1993,160(5):411-412
Dimethylsulfoniopropionate, an osmolyte of marine algae, is thought to be the major precursor of dimethyl sulfide, which plays a dominant role in biogenic sulfur emission. The marine sulfate-reducing bacterium Desulfobacterium strain PM4 was found to degrade dimethylsulfoniopropionate to 3-S-methylmercaptopropionate. The oxidation of one of the methyl groups of dimethylsulfoniopropionate was coupled to the reduction of sulfate; this process is similar to the degradation betaine to dimethylglycine which was described earlier for the same strain. Desulfobacterium PM4 is the first example of an anaerobic marine bacterium that is able to demethylate dimethylsulfoniopropionate.Abbreviations DMSP
dimethylsulfoniopropionate
- DMS
dimethyl sulfide
- MMPA
3-S-methylmercaptopropionate 相似文献
67.
为挖掘微杆菌(Microbacterium sp.)XT11在黄原胶降解过程中起关键作用的功能基因,预测黄原胶降解通路,利用转录组测序技术对该菌株在不同碳源培养条件下的转录本进行测序,对差异基因进行功能富集分析。结果表明,菌株XT11以葡萄糖为对照组,以黄原胶为碳源时可获得上调差异基因213个。显著上调的基因主要富集在聚糖降解、淀粉和蔗糖代谢途径、ABC转运、苯丙氨酸代谢、丙酮酸代谢五个KEGG途径。碳水化合物活性酶(Carbohydrate-active enzymes, CAZymes)功能注释表明,位于同一基因簇上的4个CAZymes基因和黄原胶降解直接相关,其余的CAZymes基因具有潜在的黄原胶降解活性。此外,预测到磷酸转移酶系统(phosphotransferase system, PTS)和ABC转运途径(ABC transporters)参与了胞外黄原胶降解中间产物的跨膜转运。挖掘了菌株XT11中黄原胶降解过程中的功能基因,并阐述了菌株XT11的黄原胶降解通路。 相似文献
68.
69.
Sally Badawi Feda E. Mohamed Divya Saro Varghese Bassam R. Ali 《Traffic (Copenhagen, Denmark)》2023,24(8):312-333
Endoplasmic reticulum-associated protein degradation (ERAD) is a stringent quality control mechanism through which misfolded, unassembled and some native proteins are targeted for degradation to maintain appropriate cellular and organelle homeostasis. Several in vitro and in vivo ERAD-related studies have provided mechanistic insights into ERAD pathway activation and its consequent events; however, a majority of these have investigated the effect of ERAD substrates and their consequent diseases affecting the degradation process. In this review, we present all reported human single-gene disorders caused by genetic variation in genes that encode ERAD components rather than their substrates. Additionally, after extensive literature survey, we present various genetically manipulated higher cellular and mammalian animal models that lack specific components involved in various stages of the ERAD pathway. 相似文献
70.
Four centuries of cumulative impacts on a Finnish river and its estuary: an ecosystem health-approach 总被引:1,自引:0,他引:1
M. Hildén D. Rapport 《Journal of Aquatic Ecosystem Stress and Recovery (Formerly Journal of Aquatic Ecosystem Health)》1993,2(4):261-275
Changes in forest cover and draining of wetlands for agriculture appear to have caused changes in the aquatic ecosystem of the River Kyrönjoki by the 16th century. In the 19th century, a decline of salmonid fish populations was widely observed as a further sign of degradation. During the latter half of the present century intensified use of naturally acidic soils has resulted in increased acidic run-off. Deterioration of water quality has extended to the estuary, where it has caused large fish-kills and affected the reproductive success of coastal species. Degradation of the coastal ecosystem, first observed in the decline of salmonids and later as a more general decline of other coastal fish populations, can be linked to spatially restricted events. The loss of key river and estuarine habitats exerted an effect over the reproduction and abundance of species migrating throughout the system. This effect contributed to observed temporal and spatial discontinuities in the degradation history. Monitoring changes in critical habitats may prove to be an early indicator of changes in the health of estuarine and coastal aquatic ecosystems. 相似文献