Multifunctional protein YB-1, which takes a part in many DNA/RNA-associated events in cells (transcription, mRNA translation, splicing) is a promising prognostic and predictive marker for various ...human tumors. Recently it was discovered that protein YB-1 secreted by cells functions as an extracellular mitogen. These results were obtained on kidney mesangial cells and monocytes. Here we studied the effects of extracellular YB-1 on the cell number, migration and gene expression in the populations of three lines of human malignant breast cells (MCF-7, HBL-100, BT-474). We used recombinant full-length protein YB-1, which retained all the functional sites necessary for its various activities, including binding to the receptor Notch-3 (rYB-1). Extracellular rYB-1 increased the number of cells 2- to 3-fold in the tested lines. The wound was made in cell monolayers of HBL-100, MCF-7 and MCF-7/ras. Protein rYB-1 increased the rate of wound healing in MCF-7/ras. Sensitivity to chemotherapeutic agents did not change in the presence of rYB-1 in any of the cell lines studied. We have used expression microarrays to study the effects of rYB-1 on the profile of gene expression in MCF-7 cells and in MCF-7 cells transfected with YB-1-GFP construct. In MCF-7 cells extracellular rYB-1 mainly down-regulated different genes, while in the cells transfected with cDNA of YB-1-GFP the activity of different genes was up-regulated. Our results show that extracellular YB-1 protein and intracellular YB-1 produce diverse changes in the cells of mammary tumors. It is possible that extracellular YB-1 is involved in the regulation of cell proliferation and migration in the metastatic niche.
Primary very high energy \(\gamma\)-rays from \(\gamma\)-ray bursts (GRBs) are partially absorbed on extragalactic background light (EBL) photons with subsequent formation of intergalactic ...electromagnetic cascades. Characteristics of the observable cascade \(\gamma\)-ray signal are sensitive to the strength and structure of the extragalactic magnetic field (EGMF). GRB 190114C was recently detected with the MAGIC imaging atmospheric Cherenkov telescopes, for the first time allowing to estimate the observable cascade intensity. We inquire whether any constraints on the EGMF strength and structure could be obtained from publicly-available \(\gamma\)-ray data on GRB 190114C. We present detailed calculations of the observable cascade signal for various EGMF configurations. We show that the sensitivity of the Fermi-LAT space \(\gamma\)-ray telescope is not sufficient to obtain such constraints on the EGMF parameters. However, next-generation space \(\gamma\)-ray observatories such as MAST would be able to detect pair echoes from GRBs similar to GRB 190114C for the EGMF strength below 10^{-17}--10^{-18} G.
The SPHERE project studies primary cosmic rays by detection of the Cherenkov light of extensive air showers reflected from the snowy surface of the earth. Measurements with the aerial-based detector ...SPHERE-2 were performed in 2011-2013. The detector was lifted by the balloon at altitudes up to 900 m above snowed surface of Lake Baikal, Russia. The results of the experiment are summarized now in a series of papers that opens with this article. An overview of the SPHERE-2 detector telemetry monitoring systems is presented along with the analysis of the measurements conditions including atmosphere profile. The analysis of the detector state and environment atmosphere conditions monitoring provided various cross-checks of detector calibration, positioning and performance.
We report on an observation of the difference between northern and southern skies of the ultrahigh energy cosmic ray energy spectrum with a significance of \({\sim}8\sigma\). We use measurements from ...the two largest experiments\(\unicode{x2014}\)the Telescope Array observing the northern hemisphere and the Pierre Auger Observatory viewing the southern hemisphere. Since the comparison of two measurements from different observatories introduces the issue of possible systematic differences between detectors and analyses, we validate the methodology of the comparison by examining the region of the sky where the apertures of the two observatories overlap. Although the spectra differ in this region, we find that there is only a \(1.8\sigma\) difference between the spectrum measurements when anisotropic regions are removed and a fiducial cut in the aperture is applied.
Isotropic diffuse gamma-ray flux in the PeV energy band is an important tool for multimessenger tests of models of the origin of high-energy astrophysical neutrinos and for new-physics searches. So ...far, this flux has not yet been observed. Carpet-2 is an air-shower experiment capable of detecting astrophysical gamma rays with energies above 0.1 PeV. Here we report the upper limits on the isotropic gamma-ray flux from Carpet-2 data obtained in 1999-2011 and 2018-2022. These results, obtained with the new statistical method based on the shape of the muon-number distribution, summarize Carpet-2 observations as the upgraded installation, Carpet-3, starts its operation.
Blazars may accelerate protons and/or nuclei as well as electrons. The
hadronic component of accelerated particles in blazars may constitute the bulk
of their high-energy budget; nevertheless, this ...component is elusive due to a
high value of the energy threshold of proton interaction with photon fields
inside the source. However, broad line regions (BLRs) of some flat spectrum
radio quasars (FSRQs) may contain a sufficient amount of matter to render
primary protons "visible" in $\gamma$ rays via hadronuclear interactions. In
the present paper we study the persistent $\gamma$-ray emission of the FSRQ PKS
1510-089 in its low state utilizing the publicly-available Fermi-LAT data, as
well as using the spectrum measured with the MAGIC imaging atmospheric
Cherenkov telescopes. We find an indication for an excess of $\gamma$ rays at
the energy range $\gtrsim 20$ GeV with respect to a simple baseline
log-parabolic intrinsic spectral model. This excess could be explained in a
scenario invoking hadronuclear interactions of primary protons on the BLR
material with the subsequent development of electromagnetic cascades in photon
fields. We present a Monte Carlo calculation of the spectrum of this cascade
component, taking as input the BLR photon field spectrum calculated with the
Cloudy code. To our knowledge, this is the first calculation of electromagnetic
cascade spectrum inside a blazar based on a direct calculation of the photon
field spectrum with a spectral synthesis code.
Galactic sites of acceleration of cosmic rays to energies of order 10^15 eV and higher, dubbed PeVatrons, reveal themselves by recently discovered gamma radiation of energies above 100 TeV. However, ...joint gamma-ray and neutrino production, which marks unambiguously cosmic-ray interactions with ambient matter and radiation, was not observed until now. In November 2020, the IceCube neutrino observatory reported an ~150 TeV neutrino event from the direction of one of the most promising Galactic PeVatrons, the Cygnus Cocoon. Here we report on the observation of a 3.1-sigma (post trial) excess of atmospheric air showers from the same direction, observed by the Carpet-2 experiment and consistent with a few-months flare in photons above 300 TeV, in temporal coincidence with the neutrino event. The fluence of the gamma-ray flare is of the same order as that expected from the neutrino observation, assuming the standard mechanism of neutrino production. This is the first evidence for the joint production of high-energy neutrinos and gamma rays in a Galactic source.
The SPHERE-2 balloon-borne detector designed for extensive air shower (EAS) observations using EAS optical Vavilov-Cherenkov radiation (``Cherenkov light''), reflected from the snow-covered surface ...of Lake Baikal is described. We briefly discuss the concept behind the reflected Cherenkov light method, characterize the conditions at the experimental site and overview the construction of the tethered balloon used to lift the SPHERE-2 telescope above the surface. This paper is mainly dedicated to a detailed technical description of the detector, including its optical system, sensitive elements, electronics, and data acquisition system (DAQ). The results of some laboratory and field tests of the optical system are presented.
Blazars may accelerate protons and/or nuclei as well as electrons. The hadronic component of accelerated particles in blazars may constitute the bulk of their high-energy budget; nevertheless, this ...component is elusive due to a high value of the energy threshold of proton interaction with photon fields inside the source. However, broad line regions (BLRs) of some flat spectrum radio quasars (FSRQs) may contain a sufficient amount of matter to render primary protons "visible" in \(\gamma\) rays via hadronuclear interactions. In the present paper we study the persistent \(\gamma\)-ray emission of the FSRQ PKS 1510-089 in its low state utilizing the publicly-available Fermi-LAT data, as well as using the spectrum measured with the MAGIC imaging atmospheric Cherenkov telescopes. We find an indication for an excess of \(\gamma\) rays at the energy range \(\gtrsim 20\) GeV with respect to a simple baseline log-parabolic intrinsic spectral model. This excess could be explained in a scenario invoking hadronuclear interactions of primary protons on the BLR material with the subsequent development of electromagnetic cascades in photon fields. We present a Monte Carlo calculation of the spectrum of this cascade component, taking as input the BLR photon field spectrum calculated with the Cloudy code. To our knowledge, this is the first calculation of electromagnetic cascade spectrum inside a blazar based on a direct calculation of the photon field spectrum with a spectral synthesis code.
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