531 research outputs found
Diagnosis of Cancer Spread Using Percutaneous Transhepatic Biliary Cholangioscopy-guided Ultrasonography for Malignant Bile Duct Stenosis
The characteristics of sites of intramural cancer spread were examined by comparing the
intraductal ultrasonography (IDUS) and wall thickening findings at sites of intramural cancer
spread and non-spread, in patients with malignant bile duct stenosis who had undergone
percutaneous transhepatic biliary drainage (PTBD)
Detection of physical interactions by immunoprecipitation of FLAG- and HA-tagged proteins expressed at the his-3 locus in Neurospora crassa
Protein function is often regulated through interactions with other protein(s) or by post-translational modifications. To understand these mechanisms, it is useful to utilize antibodies. However, it is not always certain whether a good antibody can be made for this purpose. The use of epitope tags eliminates the troubles associated with raising antibodies. In this report, we present a method to detect interactions between proteins by using two types of epitope-tagged proteins, FLAG- and HA-tagged proteins in Neurospora. These constructs were introduced at and expressed from the his-3 locus in different strains. To examine protein-protein interactions, heterokaryons between these strains were constructed. We conclude that this strategy is a useful tool to investigate protein function and protein interactions
Srs2 and RecQ homologs cooperate in mei-3-mediated homologous recombination repair of Neurospora crassa
Homologous recombination and post-replication repair facilitate restart of stalled or collapsed replication forks. The SRS2 gene of Saccharomyces cerevisiae encodes a 3′–5′ DNA helicase that functions both in homologous recombination repair and in post-replication repair. This study identifies and characterizes the SRS2 homolog in Neurospora crassa, which we call mus-50. A knockout mutant of N.crassa, mus-50, is sensitive to several DNA-damaging agents and genetic analyses indicate that it is epistatic with mei-3 (RAD51 homolog), mus-11 (RAD52 homolog), mus-48 (RAD55 homolog) and mus-49 (RAD57 homolog), suggesting a role for mus-50 in homologous recombination repair. However, epistasis evidence has presented that MUS50 does not participate in post-replication repair in N.crassa. Also, the N.crassa mus-25 (RAD54 homolog) mus-50 double mutant is viable, which is in contrast to the lethal phenotype of the equivalent rad54 srs2 mutant in S.cerevisiae. Tetrad analysis revealed that mus-50 in combination with mutations in two RecQ homologs, qde-3 and recQ2, is lethal, and this lethality is suppressed by mutation in mei-3, mus-11 or mus-25. Evidence is also presented for the two independent pathways for recovery from camptothecin-induced replication fork arrest: one pathway is dependent on QDE3 and MUS50 and the other pathway is dependent on MUS25 and RECQ2
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Prospect for Future MeV Gamma-ray Active Galactic Nuclei Population Studies
While the X-ray, GeV gamma-ray, and TeV gamma-ray skies have been extensively
studied, the MeV gamma-ray sky is not well investigated after the Imaging
Compton Telescope (COMPTEL) scanned the sky about two decades ago. In this
paper, we investigate prospects for active galactic nuclei population studies
with future MeV gamma-ray missions using recent spectral models and luminosity
functions of Seyfert and flat spectrum radio quasars (FSRQs). Both of them are
plausible candidates as the origins of the cosmic MeV gamma-ray background. If
the cosmic MeV gamma-ray background radiation is dominated by non-thermal
emission from Seyferts, the sensitivity of 10^-12 erg cm^-2 s^-1 is required to
detect several hundred Seyferts in the entire sky. If FSRQs make up the cosmic
MeV gamma-ray background, the sensitivity of ~4 x 10^-12 erg cm^-2 s^-1 is
required to detect several hundred FSRQs following the recent FSRQ X-ray
luminosity function. However, based on the latest FSRQ gamma-ray luminosity
function, with which FSRQs can explain up to ~30% of the MeV background, we can
expect several hundred FSRQs even with the sensitivity of 10^-11 erg cm^-2 s^-1
which is almost the same as the sensitivity goal of the next generation MeV
telescopes.Comment: 9 pages, 5 figures, accepted for publication in PAS
The origin of MeV gamma-ray diffuse emission from the inner Galactic region
The origin of the inner Galactic emission, measured by COMPTEL with a flux of
MeV cm s sr in the 1-30 MeV range, has
remained unsettled since its discovery in 1994. We investigate the origin of
this emission by taking into account individual sources which are not resolved
by COMPTEL and the Galactic diffuse emission. The source contribution is
estimated for sources crossmatched between the Swift-BAT and Fermi-LAT catalogs
by interpolating the energy spectra in the hard X-ray and GeV gamma-ray ranges,
as well as unmatched sources. This results in a flux of 20% of the
COMPTEL excess. The Galactic diffuse emission is calculated by GALPROP to
reconcile the cosmic-ray and gamma-ray spectra with observations by AMS-02,
Voyager, and Fermi-LAT, resulting in a flux of 30-80% of the COMPTEL
emission. Thus, we show that the COMPTEL emission could be roughly reproduced
by a combination of the sources and the Galactic diffuse emission. Furthermore,
combined with the extragalactic emission, we construct all-sky images in the
MeV gamma-ray range to pinpoint some potential interesting targets for future
missions, which would be critical for bridging the MeV gap in the spectra of
gamma-ray sources.Comment: Proceedings of Science; 7th Heidelberg International Symposium on
High-Energy Gamma-Ray Astronomy (Gamma2022), 4-8 July 2022, Barcelona, Spai
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