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21.
Andrew J. Millar Sharla R. Short Kazuyuki Hiratsuka Nam-Hai Chua Steve A. Kay 《Plant Molecular Biology Reporter》1992,10(4):324-337
The firefly luciferase, assayedin vivo with a low-light video camera, acts as a non-invasive, real-time reporter of the temporal and spatial regulation of gene
expression in single plants. Furthermore, the sensitivity of the luciferase assay in extracts of transformed plant tissue
makes it a particularly useful marker in transient or stable transformation experiments. 相似文献
22.
Maria S. Kuyukina Irena B. Ivshina Marina K. Serebrennikova Anastasiya B. Krivorutchko Elena A. Podorozhko Roman V. Ivanov Vladimir I. Lozinsky 《International biodeterioration & biodegradation》2009,63(4):427-432
Biotreatment of petroleum-contaminated water in a fluidized-bed bioreactor (FBB) is a relatively new and promising technology, which efficiency is strongly affected by the biocatalyst used. Our laboratory experiments involved biotreatment of the water contaminated with a synthetic petroleum mixture consisting of aliphatic and polyaromatic hydrocarbons (PAHs) using a continuous column bioreactor with recycle. Different type biocatalysts were tested, including Rhodococcus bacteria immobilized in hydrophobized carriers such as sawdust, poly(vinyl alcohol) cryogel (cryoPVA) and poly(acrylamide) cryogel (cryoPAAG). Biocatalyst abilities to oxidize petroleum hydrocarbons were evaluated using the Columbus Micro-Oxymax® respirometer. The hydrophobized sawdust-supported biocatalyst demonstrated substantially higher metabolic activity than C12-cryoPAAG-based biocatalyst due to larger number of immobilized Rhodococcus cells and, therefore, had benefits for application in FBBs. The obtained results showed that designed FBB process is successful, providing 70–100% removal of n-alkanes (C10–C19) and 66–70% removal of 2–3-ring PAHs from contaminated water after 2–3 weeks. 相似文献
23.
Although the progression of aging and the diseases associated with it are extensively studied, little is known about the initiation
of the aging process. Telomerase is down-regulated early in embryonic differentiation, thereby contributing to telomeric attrition
and aging. The mechanisms underlying this inhibition remain elusive, but epigenetic studies in differentiating human embryonic
stem (hES) cells could give clues about how and when DNA methylation and histone deacetylation work together to contribute
to the inactivation of hTERT, the catalytic subunit of telomerase, at the onset of the aging process. We have confirmed the differentiation status of
cultured hES colonies with morphological assessment and immunohistochemical stainings for pluripotent stem cells. In hES cells
with varying degrees of differentiation, we have shown a stronger association between hES differentiation and expression of
the epigenetic regulators DNMT3A and DNMT3B than between genetic modulators of differentiation such as c-MYC. We also propose
a new model system for analyses of stem cell regions, which are differentially down-regulating the expression of hTERT and the actions of epigenetic modulators such as the DNMTs and histone methyltransferases. 相似文献
24.
Sinead C. Leahy William J. Kelly Eric Altermann Ron S. Ronimus Carl J. Yeoman Diana M. Pacheco Dong Li Zhanhao Kong Sharla McTavish Carrie Sang Suzanne C. Lambie Peter H. Janssen Debjit Dey Graeme T. Attwood 《PloS one》2010,5(1)
Background
Methane (CH4) is a potent greenhouse gas (GHG), having a global warming potential 21 times that of carbon dioxide (CO2). Methane emissions from agriculture represent around 40% of the emissions produced by human-related activities, the single largest source being enteric fermentation, mainly in ruminant livestock. Technologies to reduce these emissions are lacking. Ruminant methane is formed by the action of methanogenic archaea typified by Methanobrevibacter ruminantium, which is present in ruminants fed a wide variety of diets worldwide. To gain more insight into the lifestyle of a rumen methanogen, and to identify genes and proteins that can be targeted to reduce methane production, we have sequenced the 2.93 Mb genome of M. ruminantium M1, the first rumen methanogen genome to be completed.Methodology/Principal Findings
The M1 genome was sequenced, annotated and subjected to comparative genomic and metabolic pathway analyses. Conserved and methanogen-specific gene sets suitable as targets for vaccine development or chemogenomic-based inhibition of rumen methanogens were identified. The feasibility of using a synthetic peptide-directed vaccinology approach to target epitopes of methanogen surface proteins was demonstrated. A prophage genome was described and its lytic enzyme, endoisopeptidase PeiR, was shown to lyse M1 cells in pure culture. A predicted stimulation of M1 growth by alcohols was demonstrated and microarray analyses indicated up-regulation of methanogenesis genes during co-culture with a hydrogen (H2) producing rumen bacterium. We also report the discovery of non-ribosomal peptide synthetases in M. ruminantium M1, the first reported in archaeal species.Conclusions/Significance
The M1 genome sequence provides new insights into the lifestyle and cellular processes of this important rumen methanogen. It also defines vaccine and chemogenomic targets for broad inhibition of rumen methanogens and represents a significant contribution to worldwide efforts to mitigate ruminant methane emissions and reduce production of anthropogenic greenhouse gases. 相似文献25.
Kuyukina MS Ivshina IB Gavrin AY Podorozhko EA Lozinsky VI Jeffree CE Philp JC 《Journal of microbiological methods》2006,65(3):596-603
A simple biosurfactant-based hydrophobization procedure for poly(vinyl alcohol) (PVA) cryogels was developed allowing effective immobilization of hydrocarbon-oxidizing bacteria. The resulting partially hydrophobized PVA cryogel granules (granule volume 5 microl) contained sufficient number (6.5 x 10(3)) of viable bacterial cells per granule, possessed high mechanical strength and spontaneously located at the interface in water-hydrocarbon system. Such interfacial location of PVA granules allowed high contact of immobilized biocatalyst with hydrophobic substrate and water phase, thus providing bacterial cells with mineral and organic nutrients. As a result, n-hexadecane oxidation efficiency of 51% after 10-day incubation was achieved using immobilized biocatalyst. PVA cryogels with increased hydrophobicity can be used for immobilization of bacterial cultures performing oxidative transformations of water-immiscible organic compounds. Immobilization of in situ biosurfactant producing Rhodococcus bacteria into PVA cryogel is discussed. PVA cryogel granules with entrapped alkanotrophic rhodococcal cells were stable after 10-month storage at room temperature. 相似文献
26.
Ribas A Vo DD Weeks DL Comin-Anduix B Schumacher LY Garban HJ McLean C Yang J Dissette VB Peraza P Owens SK McBride WH Glaspy JA Economou JS 《Cancer immunology, immunotherapy : CII》2006,55(6):663-671
Dendritic cell (DC) administration to CD8α knock-out (CD8αKO) mice results in a strong antigen-non-specific protection to
a B16 murine melanoma tumor challenge. This response is mediated by lytic NK cells and cytokine-producing CD4 cells. We aimed
to determine the signals that guide tumor targeting of this response. CD8αKO mice in the C57BL/6 background received subcutaneous
(s.c.) injections of immature DC. Mice were challenged in vivo or assayed for lytic activity in vitro to a panel of syngeneic
tumors with different levels of MHC class I expression. These studies support the following conclusions: (1) DC administration
to CD8αKO mice results in protective in vivo responses to syngeneic tumors from epithelial, neuroectodermal and hematopoietic
origin; in vivo protection is independent of the level of MHC classes I and II expression. (2) The in vitro lytic activity
of DC-activated NK cells from CD8αKO mice has sensitive and insensitive targets, which is independent of the cell lineage
or the level of inhibitory self-MHC surface molecules. (3) In sensitive targets a putative activating NK ligand in DC-stimulated
NK cells from CD8αKO mice signals directly to PI3-K, but is distinct from NKG2D. 相似文献
27.
28.
Anatoly F Vanin Natalia A Sanina Vladimir A Serezhenkov Dosymzhan Sh Burbaev Vladimir I Lozinsky Sergey M Aldoshin 《Nitric oxide》2007,16(1):82-93
Parameters of the EPR signals of monomeric dinitrosyl-iron complexes with 1H-1,2,4-triazole-3-thiol (DNIC-MT), obtained by treating MT+ferrous iron in DMSO solution with gaseous NO, have been compared with those of the crystalline monomeric DNIC-MT with tetrahedral structure. Dissolved DNIC-MT were characterized by the isotropic EPR signal centered at g=2.03 with half-width of 0.7 mT and quintet hyperfine structure when recorded at ambient temperature or the anisotropic EPR signal with g( perpendicular)=2.045, g( parallel)=2.014 from frozen solution at 77 kappa, Cyrillic. DNIC-MT in crystalline state showed the structure-less symmetrical singlet EPR signal centered at g=2.03 and half-width of 1.7 mT at both room and liquid nitrogen temperature. The Lorentz shape of this signal indicates the strong exchange interaction between these complexes in the DNIC-MT crystal. Being dissolved in DMSO the crystalline sample of DNIC-MT demonstrated the EPR signal typical for DNIC-MT, obtained by treating MT+ferrous iron in DMSO solution with gaseous NO. Low spin (S=1/2) d(9) electron configuration of DNIC-MT with tetrahedral structure (formula [(MT-S(.))(2)Fe(-1)(NO(+))(2)](+)) was suggested to be responsible for the signal of DNIC-MT in crystalline state. Dissolving of the crystals of DNIC-MT may result in the change of their spatial and electronic structure, namely, tetrahedral structure of the complexes characterized by low spin d(9) electronic configuration transforms into a plane-square structure with d(7) electronic configuration and low spin S=1/2 state (formula [(MT- S(-))(2)Fe(+)(NO(+))(2)](+)). The latter was suggested to be characteristic of other DNICs with various thiol-containing ligands in the solutions. The proposed mechanism of these DNICs formation from ferrous iron, thiol and NO shows that the process could be accompanied by the ionization of NO molecules to NO(+) and NO(-) ions in the complexes. Detailed analysis of the shape of the EPR signals of these complexes provided additional information about the exchange interaction typical for DNIC-MT in crystals. 相似文献
29.
The potential of polymeric cryogels in bioseparation 总被引:3,自引:0,他引:3
This is a review discussing the production and properties of cryogels (from the Greek κριoσ (kryos) meaning frost or ice),
immobilization of ligands in cryogels and the application of affinity cryogels in bioseparation. Cryotropic gel formation
proceeds in a non-frozen liquid microphase existing in the macroscopically frozen sample. Due to the cryoconcentration of
gel precursors in the non-frozen liquid microphase, cryogelation is characterised by a decrease in the critical concentration
of gelation and an increase in gelation rates compared with traditional gelation at temperatures above freezing point.
Cryogels can be obtained through the formation of both physically and covalently cross-linked heterogeneous polymer networks.
Interconnected systems of macropores and sponge-like morphology are typical for cryogels, allowing unhindered diffusion of
solutes of practically any size. Most of the water present in spongy cryogels is capillary bound and can be removed mechanically
by squeezing. The properties of cryogels can be regulated by the temperature of cryogelation, the time the sample is kept
in a frozen state and freezing/thawing rates, by the nature of the solvent and by the use of soluble and insoluble additives.
The unique macroporous morphology of cryogels, in combination with osmotic, chemical and mechanical stability, makes them
attractive matrices for chromatography of large entities such as protein aggregates, membrane fragments, viruses, cell organells
and even whole cells. Special attention is given to immunosorption of viruses on cryogel-based sorbents. As chromatographic
materials, cryogels can be used both in bead form and as spongy cylindrical blocks (monoliths) synthesized inside the chromatographic
column. The macroporous nature of cryogels is also advantageous for their application as matrices in the immobilization of
biocatalysts operating in both aqueous and organic solvents. New potential applications of cryogels are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
30.
Heterogeneity in the structural dynamics of Sulfolobus solfataricus beta-glycosidase revealed by electron paramagnetic resonance and frequency domain fluorometry 下载免费PDF全文
Lozinsky E Febbraio F Shames AI Likhtenshtein GI Bismuto E Nucci R 《Protein science : a publication of the Protein Society》2002,11(11):2535-2544
The local and global dynamics of the Sulfolobus solfataricus beta-glycosidase were studied by electron spin resonance and time-resolved fluorescence techniques. For electron paramagnetic resonance (EPR) investigations, the protein was covalently modified by the maleimido nitroxide spin label, which is specific for cysteine -SH groups, at position 344 and at position 101, where Ser-101 was changed into a cysteine by site-directed mutagenesis. The greater reactivity of exposed Cys-101 suggested the exclusive modification of this amino acid compared with Cys-344. The labeled proteins underwent temperature perturbation in the range 290-335 K and the values of the spin-label rotation correlation frequencies (nu(c)) ranged from 6 x 10(7) to 2 x 10(8) sec(-1) for the protein labeled at position C344 and from 5.62 x 10(7) to 1.10 x 10(8) sec(-1) for the protein labeled at C101. These rotation correlation values are related to the local dynamic characteristics of the protein matrix. The temperature dependence of rotation correlation frequencies expressed in terms of Arrhenius coordinates (log (nu(c)) vs. 1/T) for the protein labeled at C344 exhibited a linear dependence but with a change in the slope at 311 K. For the protein labeled at C101, no change in the slope was observed at the same temperature. General dynamic information was deduced from the analysis of the fluorescence emission decay of the tryptophanyl residues that are present in each region of the protein structure. Fluorescence data analysis highlighted a bimodal distribution of fluorescence lifetimes arising from the contribution of two emitting groups: one consisting of closely clustered tryptophans responsible for the long-lived emission component (7.1 nsec) and the other composed of tryptophans nearer to the protein surface, which can be associated to the short-lived component (2.5 nsec). The temperature dependence of lifetime distribution parameters linked to the long-lived and short-lived components, expressed in Arrhenius coordinates, showed two different points in which the change in the slope occurred (i.e., 328 K and 338 K, respectively). The Arrhenius analysis of data provided the activation energy relative to the conformational changes characterizing the local and global movements running through the protein matrix. 相似文献