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81.
82.
Viral O-acetylesterases were first identified in several viruses, including influenza C viruses and coronaviruses. These enzymes are capable of removing cellular receptors from the surface of target cells. Hence they are also known as "receptor destroying" enzymes. We have cloned and expressed several recombinant viral O-acetylesterases. These enzymes were secreted from Sf9 insect cells as chimeric proteins fused to eGFP. A purification scheme to isolate the recombinant O-acetylesterase of influenza C virus was developed. The recombinant enzymes derived from influenza C viruses specifically hydrolyze 9-O-acetylated sialic acids, while that of sialodacryoadenitis virus, a rat coronavirus related to mouse hepatitis virus, is specific for 4-O-acetylated sialic acid. The recombinant esterases were shown to specifically de-O-acetylate sialic acids on glycoconjugates. We have also expressed esterase knockout proteins of the influenza C virus hemagglutinin-esterase. The recombinant viral proteins can be used to unambiguously identify O-acetylated acids in a variety of assays. 相似文献
83.
The lipocalin Xlcpl1 expressed in the neural plate of Xenopus laevis embryos is a secreted retinaldehyde binding protein. 总被引:1,自引:1,他引:0
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G. Lepperdinger B. Strobl A. Jilek A. Weber J. Thalhamer H. Flckner C. Mollay 《Protein science : a publication of the Protein Society》1996,5(7):1250-1260
The cellular and structural properties and binding capabilities of a lipocalin expressed in the early neural plate of Xenopus laevis embryos and the adult choroid plexus have been investigated. It was found that this lipocalin, termed Xlcpl1, binds retinal at a nanomolar concentration, retinoic acid in the micromolar range, but does not show binding to retinol. Furthermore, this protein also binds D/L thyroxine. The Xlcpl1 cDNA was expressed in cell culture using the vaccinia virus expression system. In AtT20 cells, Xlcpl1 was secreted via the constitutive secretory pathway. We therefore assume that cpl1 binds retinaldehyde during the transport through the compartments of the secretory pathway that are considered to be the storage compartments of retinoids. Therefore, cpl1-expressing cells will secrete the precursors of active retinoids such as retinoic acid isomers. These retinoids may enter the cytosol by diffusion or receptor-controlled mechanisms, as has been shown for exogenously applied retinoids. Based on these data, it is suggested that cpl1 is an integral member of the retinoid signaling pathway and, therefore, it plays a key role in pattern formation in early embryonic development. 相似文献
84.
A role for DNA methylation in vertebrate gene expression? 总被引:1,自引:0,他引:1
J S Strobl 《Molecular endocrinology (Baltimore, Md.)》1990,4(2):181-183
85.
Raimund M. Vielnascher Eva Hainzl Nicole R. Leitner Michael Rammerstorfer David Popp Agnieszka Witalisz Rita Rom Marina Karaghiosoff Thomas Kolbe Simone Müller Thomas Rülicke Caroline Lassnig Birgit Strobl Mathias Müller 《Transgenic research》2014,23(3):519-529
Tyrosine kinase 2 (TYK2) has a pivotal role in immunity to infection and tumor surveillance. It is associated with several cytokine receptor chains including type I interferon (IFN) receptor 1 (IFNAR1), interleukin- (IL-) 12 receptor beta 1 (IL-12Rb1) and IL-10R2. We have generated a mouse with a conditional Tyk2 null allele and proved integrity of the conditional Tyk2 locus. TYK2 was successfully removed by the use of ubiquitous and tissue-specific Cre-expressing mouse strains. Myeloid TYK2 was found to critically contribute to the defense against murine cytomegalovirus. Ubiquitous TYK2 ablation severely impaired tumor immunosurveillance, while deletion in myeloid, dendritic or T cells alone showed no effect. The conditional Tyk2 mouse strain will be instrumental to further dissect TYK2 functions in infection, inflammation and cancer. 相似文献
86.
Westerhausen C Strobl FG Herrmann R Bauer AT Schneider SW Reller A Wixforth A Schneider MF 《Biophysical journal》2012,102(5):1032-1038
The interaction of nanoparticles (NPs) with lipid membranes is an integral step in the interaction of NPs and living cells. During particle uptake, the membrane has to bend. Due to the nature of their phase diagram, the modulus of compression of these membranes can vary by more than one order of magnitude, and thus both the thermodynamic and mechanical aspects of the membrane have to be considered simultaneously. We demonstrate that silica NPs have at least two independent effects on the phase transition of phospholipid membranes: 1), a chemical effect resulting from the finite instability of the NPs in water; and 2), a mechanical effect that originates from a bending of the lipid membrane around the NPs. Here, we report on recent experiments that allowed us to clearly distinguish both effects, and present a thermodynamic model that includes the elastic energy of the membranes and correctly predicts our findings both quantitatively and qualitatively. 相似文献
87.
Recently, there has been an increasing interest in using the biomechanical properties of cells as biomarkers to discriminate between normal and cancerous cells. However, few investigators have considered the influence of the growth medium composition when evaluating the biomechanical properties of the normal and diseased cells. In this study, we investigated the variation in Young's modulus of non-malignant MCF10A and malignant MDA-MB-231 breast cells seeded in five different growth media under controlled experimental conditions. The average Young's modulus of MDA-MB-231 cells was significantly lower (p<0.0001) than the mean Young's modulus of MCF10A cells when compared in identical medium compositions. However, we found that growth medium composition affected the elasticity of MCF10A and MDA-MB-231 cells. The average Young's modulus of both cell lines decreased by 10-18% when the serum was reduced from 10% to 5% and upon addition of epidermal growth factor (EGF, 20 ng/ml) to the medium. Though these elasticity changes might have some biological impact, none was statistically significant. However, the elasticity of MCF10A was significantly more responsive than MDA-MB-231 cells to the medium composition supplemented with EGF, cholera toxin (CT), insulin (INS) and hydrocortisone (HC), which are recommended for routine cultivation of MCF10A cells (M5). MCF10A cells were significantly softer (p<0.002) when grown in medium M5 compared to a standard MDA-MB-231 medium (M1). The investigation of the effects of culture medium composition on the elastic properties of cells highlights the need to take these effects into consideration when interpreting elasticity measurements in cells grown in different media. 相似文献
88.
Plantations of exotic trees on areas where tropical forest has been clear-felled have been reported to facilitate regrowth
of indigenous tree species. This so-called nurse- or shelter tree effect was investigated in a montane semihumid site in southern
Ethiopia where plantations of Pinus patula and Eucalyptus saligna grow in close vicinity to the natural Podocarpus falcatus mixed forest. Physiological performance of P. falcatus saplings growing in the exotic and the natural forests was investigated over the year. Compared with the natural forest,
photosynthetic carbon gain and growth of the saplings were significantly enhanced under Pinus patula while likewise retarded under Eucalyptus saligna. Diverging effects of the differently dense shelter canopies on the saplings could be traced to differences in the sub-canopy
microclimates and particularly to the intensities and temporal distribution of photosynthetic active radiation (PAR). Moisture
also played an important role for photosynthetic carbon gain: while the morning patterns of CO2 uptake were significantly correlated with the patterns of sunflecks, stomatal conductance was the determinant factor in the
afternoon. Analysis of the photosynthetic efficiency of sunflecks revealed a lower quantum yield than the basic diffuse PAR
intensity. Compared with a theoretically even distribution of the daily PAR, CO2 uptake under the real light climate was 70% under Pinus and in the natural forest, and 59% under Eucalyptus. Relating growth rates of Podocarpus saplings to photosynthesis the microclimate under Pinus was 2.5 times as effective as that in the natural forest and five times more effective than under Eucalyptus. 相似文献
89.
90.
Sandra Ortlieb Lukas Gorzelniak Dennis Nowak Ralf Strobl Eva Grill Barbara Thorand Annette Peters Klaus A. Kuhn Stefan Karrasch Alexander Horsch Holger Schulz 《PloS one》2014,9(11)