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21.
Kristine Lysnes Gunhild Bødtker Terje Torsvik Eva Ø. Bjørnestad Egil Sunde 《Applied microbiology and biotechnology》2009,83(6):1143-1157
The microbial response to produced water reinjection (PWRI) in a North Sea oil field was investigated by a combination of
cultivation and culture-independent molecular phylogenetic techniques. Special emphasise was put on the relationship between
sulphate-reducing bacteria (SRB) and nitrate-reducing bacteria (NRB), and results were used to evaluate the possibility of
nitrate treatment as a souring management tool during PWRI. Samples were collected by reversing the flow of the injection
water, which provided samples from around the injection area. The backflowed samples were compared to produced water from
the same platform and to backflowed samples from a biocide-treated seawater injector, which was the previous injection water
treatment of the PWRI well. Results showed that reinjection of produced water promoted growth of thermophilic SRB. Thermophilic
fatty acid oxidising NRB and potential nitrate-reducing sulphide-oxidising bacteria were also found. The finding of thermophilic
NRB makes nitrate treatment during PWRI possible, although higher nitrate concentration will be necessary to compensate for
the increased SRB activity. 相似文献
22.
Gunhild Bødtker Kristine Lysnes Terje Torsvik Eva Ø. Bjørnestad Egil Sunde 《Journal of industrial microbiology & biotechnology》2009,36(3):439-450
Reservoir souring in offshore oil fields is caused by hydrogen sulphide (H2S) produced by sulphate-reducing bacteria (SRB), most often as a consequence of sea water injection. Biocide treatment is
commonly used to inhibit SRB, but has now been replaced by nitrate treatment on several North Sea oil fields. At the Statfjord
field, injection wells from one nitrate-treated reservoir and one biocide-treated reservoir were reversed (backflowed) and
sampled for microbial analysis. The two reservoirs have similar properties and share the same pre-nitrate treatment history.
A 16S rRNA gene-based community analysis (PCR-DGGE) combined with enrichment culture studies showed that, after 6 months of
nitrate injection (0.25 mM NO3
−), heterotrophic and chemolithotrophic nitrate-reducing bacteria (NRB) formed major populations in the nitrate-treated reservoir.
The NRB community was able to utilize the same substrates as the SRB community. Compared to the biocide-treated reservoir,
the microbial community in the nitrate-treated reservoir was more phylogenetically diverse and able to grow on a wider range
of substrates. Enrichment culture studies showed that SRB were present in both reservoirs, but the nitrate-treated reservoir
had the least diverse SRB community. Isolation and characterisation of one of the dominant populations observed during nitrate
treatment (strain STF-07) showed that heterotrophic denitrifying bacteria affiliated to Terasakiella probably contributed significantly to the inhibition of SRB.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
23.
Engesaeter BØ Tveito S Bonsted A Engebraaten O Berg K Maelandsmo GM 《The journal of gene medicine》2006,8(6):707-718
BACKGROUND: In the present study the physical targeting technique photochemical internalization (PCI) has been used in combination with adenovirus. We have previously shown that PCI enhances transgene expression from AdhCMV-lacZ, and the aim of the present study was to further increase the understanding of photochemically mediated adenoviral transduction. METHODS: Two colorectal carcinoma cell lines, WiDr and HCT116, were pre-incubated with the photosensitizer TPPS(2a) or methylene blue derivates (MBD) followed by infection with adenovirus and light exposure. Transgene expression was measured by flow cytometry. Real-time polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH) were used to quantify the level of viral DNA in the nuclei. Real-time PCR was also used to measure the level of beta-galactosidase mRNA in samples infected with AdhCMV-lacZ. RESULTS: Exposing TPPS(2a)-treated cells to light enhanced the quantity of viral DNA in the nucleus, the mRNA level of the transgene and the transgene expression compared to non-illuminated cells. The increased transgene expression was independent of the promoter used, but dependent on the time of light exposure and the cellular localization of the photosensitizer. CONCLUSIONS: The enhanced transgene expression observed after photochemical treatment is most likely not a result of one event, but more an interplay between various mechanisms. An increased level of adenoviral DNA in the nucleus and a dependency of endosomal localization of the photosensitizer to obtain enhanced transgene expression suggested that endosomal rupture facilitated the transport of adenoviruses to the nucleus. 相似文献
24.
Hughey RP Mueller GM Bruns JB Kinlough CL Poland PA Harkleroad KL Carattino MD Kleyman TR 《The Journal of biological chemistry》2003,278(39):37073-37082
The epithelial Na+ channel (ENaC) is a tetramer of two alpha-, one beta-, and one gamma-subunit, but little is known about its assembly and processing. Because co-expression of mouse ENaC subunits with three different carboxyl-terminal epitope tags produced an amiloride-sensitive sodium current in oocytes, these tagged subunits were expressed in both Chinese hamster ovary or Madin-Darby canine kidney type 1 epithelial cells for further study. When expressed alone alpha-(95 kDa), beta-(96 kDa), and gamma-subunits (93 kDa) each produced a single band on SDS gels by immunoblotting. However, co-expression of alphabetagammaENaC subunits revealed a second band for each subunit (65 kDa for alpha, 110 kDa for beta, and 75 kDa for gamma) that exhibited N-glycans that had been processed to complex type based on sensitivity to treatment with neuraminidase, resistance to cleavage by endoglycosidase H, and GalNAc-independent labeling with [3H]Gal in glycosylation-defective Chinese hamster ovary cells (ldlD). The smaller size of the processed alpha- and gamma-subunits is also consistent with proteolytic cleavage. By using alpha- and gamma-subunits with epitope tags at both the amino and carboxyl termini, proteolytic processing of the alpha- and gamma-subunits was confirmed by isolation of an additional epitope-tagged fragment from the amino terminus (30 kDa for alpha and 18 kDa for gamma) consistent with cleavage within the extracellular loop. The fragments remain stably associated with the channel as shown by immunoblotting of co-immunoprecipitates, suggesting that proteolytic cleavage represents maturation rather than degradation of the channel. 相似文献
25.
Gromov P Skovgaard GL Palsdottir H Gromova I Østergaard M Celis JE 《Molecular & cellular proteomics : MCP》2003,2(2):70-84
Aging of the human skin is a complex process that consists of chronological and extrinsic aging, the latter caused mainly by exposure to ultraviolet radiation (photoaging). Here we present studies in which we have used proteomic profiling technologies and two-dimensional (2D) PAGE database resources to identify proteins whose expression is deregulated in the epidermis of the elderly. Fresh punch biopsies from the forearm of 20 pairs of young and old donors (21-30 and 75-92 years old, respectively) were dissected to yield an epidermal fraction that consisted mainly of differentiated cells. One- to two-mm3 epidermal pieces were labeled with [35S]methionine for 18 h, lysed, and subjected to 2D PAGE (isoelectric focusing and non-equilibrium pH gradient electrophoresis) and phosphorimage autoradiography. Proteins were identified by matching the gels with the master 2D gel image of human keratinocytes (proteomics.cancer.dk). In selected cases 2D PAGE immunoblotting and/or mass spectrometry confirmed the identity. Quantitative analysis of 172 well focused and abundant polypeptides showed that the level of most proteins (148) remains unaffected by the aging process. Twenty-two proteins were consistently deregulated by a factor of 1.5 or more across the 20 sample pairs. Among these we identified a group of six polypeptides (Mx-A, manganese-superoxide dismutase, tryptophanyl-tRNA synthetase, the p85beta subunit of phosphatidylinositol 3-kinase, and proteasomal proteins PA28-alpha and SSP 0107) that is induced by interferon-gamma in primary human keratinocytes and that represents a specific protein signature for the effect of this cytokine. Changes in the expression of the eukaryotic initiation factor 5A, NM23 H2, cyclophilin A, HSP60, annexin I, and plasminogen activator inhibitor 2 were also observed. Two proteins exhibited irregular behavior from individual to individual. Besides arguing for a role of interferon-gamma in the aging process, the biological activities associated with the deregulated proteins support the contention that aging is linked with increased oxidative stress that could lead to apoptosis in vivo. 相似文献
26.
Layer G Kervio E Morlock G Heinz DW Jahn D Retey J Schubert WD 《Biological chemistry》2005,386(10):971-980
Radical SAM enzymes have only recently been recognized as an ancient family sharing an unusual radical-based reaction mechanism. This late appreciation is due to the extreme oxygen sensitivity of most radical SAM enzymes, making their characterization particularly arduous. Nevertheless, realization that the novel apposition of the established cofactors S-adenosylmethionine and [4Fe-4S] cluster creates an explosive source of catalytic radicals, the appreciation of the sheer size of this previously neglected family, and the rapid succession of three successfully solved crystal structures within a year have ensured that this family has belatedly been noted. In this review, we report the characterization of two enzymes: the established radical SAM enzyme, HemN or oxygen-independent coproporphyrinogen III oxidase from Escherichia coli, and littorine mutase, a presumed radical SAM enzyme, responsible for the conversion of littorine to hyoscyamine in plants. The enzymes are compared to other radical SAM enzymes and in particular the three reported crystal structures from this family, HemN, biotin synthase and MoaA, are discussed. 相似文献
27.
Julia Adamczack Martin Hoffmann Ulrich Papke Kristin Haufschildt Tristan Nicke Martin Br?ring Murat Sezer Rebecca Weimar Uwe Kuhlmann Peter Hildebrandt Gunhild Layer 《The Journal of biological chemistry》2014,289(44):30753-30762
Heme d1 plays an important role in denitrification as the essential cofactor of the cytochrome cd1 nitrite reductase NirS. At present, the biosynthesis of heme d1 is only partially understood. The last step of heme d1 biosynthesis requires a so far unknown enzyme that catalyzes the introduction of a double bond into one of the propionate side chains of the tetrapyrrole yielding the corresponding acrylate side chain. In this study, we show that a Pseudomonas aeruginosa PAO1 strain lacking the NirN protein does not produce heme d1. Instead, the NirS purified from this strain contains the heme d1 precursor dihydro-heme d1 lacking the acrylic double bond, as indicated by UV-visible absorption spectroscopy and resonance Raman spectroscopy. Furthermore, the dihydro-heme d1 was extracted from purified NirS and characterized by UV-visible absorption spectroscopy and finally identified by high-resolution electrospray ionization mass spectrometry. Moreover, we show that purified NirN from P. aeruginosa binds the dihydro-heme d1 and catalyzes the introduction of the acrylic double bond in vitro. Strikingly, NirN uses an electron bifurcation mechanism for the two-electron oxidation reaction, during which one electron ends up on its heme c cofactor and the second electron reduces the substrate/product from the ferric to the ferrous state. On the basis of our results, we propose novel roles for the proteins NirN and NirF during the biosynthesis of heme d1. 相似文献
28.
Nicole Bethge Ragnhild A Lothe Hilde Honne Kim Andresen Gunhild Tr?en Mette Ekn?s Knut Liest?l Harald Holte Jan Delabie Erlend B Smeland Guro E Lind 《Epigenetics》2014,9(3):428-436
Genes with altered DNA methylation can be used as biomarkers for cancer detection and assessment of prognosis. Here we analyzed the methylation status of a colorectal cancer biomarker panel (CNRIP1, FBN1, INA, MAL, SNCA, and SPG20) in 97 cancer cell lines, derived from 17 different cancer types. Interestingly, the genes were frequently methylated also in hematological cancer types and were therefore subjected to analyses in primary tumor samples from the major types of non-Hodgkin lymphomas (NHL) and in healthy controls. In total, the genes CNRIP1, FBN1, INA, MAL, SNCA, and SPG20 were methylated in 53%, 23%, 52%, 69%, 97%, and 92% of the tumor samples, respectively, and were unmethylated in all healthy controls. With the exception of a single tumor sample, a correct prediction of lymphoma or normal sample was made in a blinded analysis of the validation series using a combination of SNCA and SPG20. The combined ROC-curve analysis of these genes resulted in an area under the curve of 0.999 (P = 4.2 × 10−18), and a sensitivity and specificity of 98% and 100%, respectively, across the test and validation series. Interestingly, the promoter methylation of CNRIP1 was associated with decreased overall survival in diffuse large B-cell lymphoma (DLBCL) (P = 0.03).
In conclusion, our results demonstrate that SNCA and SPG20 methylation might be suitable for early detection and monitoring of NHL. Furthermore, CNRIP1 could potentially be used as a prognostic factor in DLBCL. 相似文献
29.
Yawu Liu Jussi Mattila Miguel ángel Mu?oz Ruiz Teemu Paajanen Juha Koikkalainen Mark van Gils Sanna-Kaisa Herukka Gunhild Waldemar Jyrki L?tj?nen Hilkka Soininen for The Alzheimer’s Disease Neuroimaging Initiative 《PloS one》2013,8(2)
Purpose
To compare the accuracies of predicting AD conversion by using a decision support system (PredictAD tool) and current research criteria of prodromal AD as identified by combinations of episodic memory impairment of hippocampal type and visual assessment of medial temporal lobe atrophy (MTA) on MRI and CSF biomarkers.Methods
Altogether 391 MCI cases (158 AD converters) were selected from the ADNI cohort. All the cases had baseline cognitive tests, MRI and/or CSF levels of Aβ1–42 and Tau. Using baseline data, the status of MCI patients (AD or MCI) three years later was predicted using current diagnostic research guidelines and the PredictAD software tool designed for supporting clinical diagnostics. The data used were 1) clinical criteria for episodic memory loss of the hippocampal type, 2) visual MTA, 3) positive CSF markers, 4) their combinations, and 5) when the PredictAD tool was applied, automatically computed MRI measures were used instead of the visual MTA results. The accuracies of diagnosis were evaluated with the diagnosis made 3 years later.Results
The PredictAD tool achieved the overall accuracy of 72% (sensitivity 73%, specificity 71%) in predicting the AD diagnosis. The corresponding number for a clinician’s prediction with the assistance of the PredictAD tool was 71% (sensitivity 75%, specificity 68%). Diagnosis with the PredictAD tool was significantly better than diagnosis by biomarkers alone or the combinations of clinical diagnosis of hippocampal pattern for the memory loss and biomarkers (p≤0.037).Conclusion
With the assistance of PredictAD tool, the clinician can predict AD conversion more accurately than the current diagnostic criteria. 相似文献30.
Metastasis is a complex cascade of events involving a finely tuned interplay between malignant cells and multiple host factors.
The transition from benign tumor growth to malignancy is manifested by the ability of tumor cells to traverse tissue barriers
and invade surrounding tissues. Among a multitude of factors playing a role, the small calcium-binding protein S100A4 has
been found to add to the invasive and metastatic capacity of cancer cells. However, the exact molecular function or mechanism
by which S100A4 exerts its putative metastasis-promoting effects has not been fully elucidated, and the protein is most likely
involved in several aspects of tumor progression. Several studies have recently described a direct interaction and/or reciprocal
influence between S100A4 and the tumor suppressor protein p53. This corresponds to reports linking p53 to other S100-family
members, especially S100B. The consequences are intriguing, connecting the metastasis-promoting protein S100A4 to the large
set of important p53-mediated functions, with broad potential importance in cancer development and metastasis. In this review
we emphasize the studies involving p53 and S100A4, elucidating and comparing reported results and conclusions. 相似文献