397 research outputs found
A Laccase with HIV-1 Reverse Transcriptase Inhibitory Activity from the Broth of Mycelial Culture of the Mushroom Lentinus tigrinus
A 59 kDa laccase with inhibitory activity against HIV-1 reverse transcriptase (IC50 = 2.4 μM) was isolated from the broth of mycelial culture of the mushroom Lentinus tigrinus. The isolation procedure involved ion exchange chromatography on DEAE-cellulose and CM-cellulose, and gel filtration by fast protein liquid chromatography on Superdex 75. The laccase was adsorbed on both types of ion exchangers. About 95-fold purification was achieved with a 25.9% yield of the enzyme. The procedure resulted in a specific enzyme activity of 76.6 U/mg. Its N-terminal amino acid sequence was GIPDLHDLTV, which showed little similarity to other mushroom laccase and other Lentinus tigrinus strain laccase. Its characteristics were different from previously reported laccase of other Lentinus tigrinus strain. Maximal laccase activity was observed at a pH of 4 and at a temperature of 60°C, respectively. This study yielded the information about the potentially exploitable activities of Lentinus tigrinus laccase
Static spherical vacuum solutions in the bumblebee gravity model
The bumblebee gravity model is a vector-tensor theory of gravitation where
the vector field nonminimally couples to the Ricci tensor. By investigating the
vacuum field equations with spherical symmetry, we find two families of
black-hole (BH) solutions in this model: one has a vanishing radial component
of the vector field and the other has a vanishing radial component of the Ricci
tensor. When the coupling between the vector field and the Ricci tensor is set
to zero, the first family becomes the Reissner-Nordstr\"om solution while the
second family degenerates to the Schwarzschild solution with the vector field
being zero. General numerical solutions in both families are obtained for
nonzero coupling between the vector field and the Ricci tensor. Besides BH
solutions, we also reveal the existence of solutions that have a nonvanishing
-component of the metric on the supposed event horizon where the
-component of the metric diverges while the curvature scalars are finite.
These solutions are not supported by existing observations but present certain
properties that are of academic interests. We conclude the study by putting the
BH solutions into tests against the Solar-system observations and the images of
supermassive BHs.Comment: 19 pages, 10 figure
Phosphorylation Modification of Wheat Lectin VER2 Is Associated with Vernalization-Induced O-GlcNAc Signaling and Intracellular Motility
BACKGROUND: O-linked beta-N-acetylglucosamine (O-GlcNAc) modification of proteins mediates stress response and cellular motility in animal cells. The plant lectin concanavalin A can increase nuclear O-GlcNAc levels and decrease cytoplasmic O-GlcNAc levels in T lymphocytes. However, the functions of O-GlcNAc signaling in plants, as well as the relation between plant lectins and O-GlcNAc in response to environmental stimuli are largely undefined. METHODOLOGY/PRINCIPAL FINDINGS: We describe a jacalin-like lectin VER2 in wheat that shows N-acetylglucosamine and galactose specificity. Immunocytochemical localization showed VER2 expression induced predominantly at potential nuclear structures in shoot tips and young leaves and weakly in cytoplasm in response to vernalization. In contrast, under devernalization (continuous stimulation with a higher temperature after vernalization), VER2 signals appeared predominantly in cytoplasm. 2-D electrophoresis, together with western blot analysis, showed phosphorylation modification of VER2 under vernalization. Immunoblot assay with O-GlcNAc-specific antibody revealed that vernalization increased O-GlcNAc modification of proteins at the global level. An O-GlcNAc-modified protein co-immunoprecipitated with VER2 in vernalized wheat plants but not in devernalized materials. The dynamic of VER2 was observed in transgenic Arabidopsis overexpressing the VER2-GFP fusion protein. Overexpressed VER2 accelerated nuclear migration. Immunogold labeling and indirect immunofluoresence colocalization assay indicated that VER2-GFP was targeted to the secretory pathway. CONCLUSIONS/SIGNIFICANCE: O-GlcNAc signaling is involved in the vernalization response in wheat, and phosphorylation is necessary for the lectin VER2 involving O-GlcNAc signaling during vernalization. Our findings open the way to studies of O-GlcNAc protein modification in response to environmental signals in plants
Moment of Inertia for Axisymmetric Neutron Stars in the Standard-Model Extension
We develop a consistent approach to calculate the moment of inertia (MOI) for
axisymmetric neutron stars (NSs) in the Lorentz-violating Standard-Model
Extension (SME) framework. To our knowledge, this is the first relativistic MOI
calculation for axisymmetric NSs in a Lorentz-violating gravity theory other
than deformed, rotating NSs in the General Relativity. Under Lorentz violation,
there is a specific direction in the spacetime and NSs get stretched or
compressed along that direction. When a NS is spinning stationarily along this
direction, a conserved angular momentum and the concept of MOI are well
defined. In the SME framework, we calculate the partial differential equation
governing the rotation and solve it numerically with the finite element method
to get the MOI for axisymmetric NSs caused by Lorentz violation. Besides, we
study an approximate case where the correction to the MOI is regarded solely
from the deformation of the NS and compare it with its counterpart in the
Newtonian gravity. Our formalism and the numerical method can be extended to
other theories of gravity for static axisymmetric NSs.Comment: 9 pages, 3 figure
-mode of neutron stars in pseudo-Newtonian gravity
The equation of state (EOS) of nuclear dense matter plays a crucial role in
many astrophysical phenomena associated with neutron stars (NSs). Fluid
oscillations are one of the most fundamental properties therein. NSs support a
family of gravity -modes, which are related to buoyancy. We study the
gravity -modes caused by composition gradient and density discontinuity in
the framework of pseudo-Newtonian gravity. The mode frequencies are calculated
in detail and compared with Newtonian and general-relativistic (GR) solutions.
We find that the -mode frequencies in one of the pseudo-Newtonian treatments
can approximate remarkably well the GR solutions, with relative errors in the
order of . Our findings suggest that, with much less computational cost,
pseudo-Newtonian gravity can be utilized to accurately analyze oscillation of
NSs constructed from an EOS with a first-order phase transition between nuclear
and quark matter, as well as to provide an excellent approximation of GR
effects in core-collapse supernova (CCSN) simulations.Comment: 14 pages, 13 figures, 6 tables; accepted by PR
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