Detection of large-scale X-ray bubbles in the Milky Way halo.

The halo of the Milky Way provides a laboratory to study the properties of the shocked hot gas that is predicted by models of galaxy formation. There is observational evidence of energy injection into the halo from past activity in the nucleus of the Milky Way1-4; however, the origin of this energy (star formation or supermassive-black-hole activity) is uncertain, and the causal connection between nuclear structures and large-scale features has not been established unequivocally. Here we report soft-X-ray-emitting bubbles that extend approximately 14 kiloparsecs above and below the Galactic centre and include a structure in the southern sky analogous to the North Polar Spur. The sharp boundaries of these bubbles trace collisionless and non-radiative shocks, and corroborate the idea that the bubbles are not a remnant of a local supernova5 but part of a vast Galaxy-scale structure closely related to features seen in γ-rays6. Large energy injections from the Galactic centre7 are the most likely cause of both the γ-ray and X-ray bubbles. The latter have an estimated energy of around 1056 erg, which is sufficient to perturb the structure, energy content and chemical enrichment of the circumgalactic medium of the Milky Way.

A very-high-energy component deep in the γ-ray burst afterglow.

Gamma-ray bursts (GRBs) are brief flashes of γ-rays and are considered to be the most energetic explosive phenomena in the Universe1. The emission from GRBs comprises a short (typically tens of seconds) and bright prompt emission, followed by a much longer afterglow phase. During the afterglow phase, the shocked outflow-produced by the interaction between the ejected matter and the circumburst medium-slows down, and a gradual decrease in brightness is observed2. GRBs typically emit most of their energy via γ-rays with energies in the kiloelectronvolt-to-megaelectronvolt range, but a few photons with energies of tens of gigaelectronvolts have been detected by space-based instruments3. However, the origins of such high-energy (above one gigaelectronvolt) photons and the presence of very-high-energy (more than 100 gigaelectronvolts) emission have remained elusive4. Here we report observations of very-high-energy emission in the bright GRB 180720B deep in the GRB afterglow-ten hours after the end of the prompt emission phase, when the X-ray flux had already decayed by four orders of magnitude. Two possible explanations exist for the observed radiation: inverse Compton emission and synchrotron emission of ultrarelativistic electrons. Our observations show that the energy fluxes in the X-ray and γ-ray range and their photon indices remain comparable to each other throughout the afterglow. This discovery places distinct constraints on the GRB environment for both emission mechanisms, with the inverse Compton explanation alleviating the particle energy requirements for the emission observed at late times. The late timing of this detection has consequences for the future observations of GRBs at the highest energies.

Search for Dark Matter Annihilation Signals in the H.E.S.S. Inner Galaxy Survey.

The central region of the Milky Way is one of the foremost locations to look for dark matter (DM) signatures. We report the first results on a search for DM particle annihilation signals using new observations from an unprecedented γ-ray survey of the Galactic Center (GC) region, i.e., the Inner Galaxy Survey, at very high energies (≳100 GeV) performed with the H.E.S.S. array of five ground-based Cherenkov telescopes. No significant γ-ray excess is found in the search region of the 2014-2020 dataset and a profile likelihood ratio analysis is carried out to set exclusion limits on the annihilation cross section ⟨σv⟩. Assuming Einasto and Navarro-Frenk-White (NFW) DM density profiles at the GC, these constraints are the strongest obtained so far in the TeV DM mass range. For the Einasto profile, the constraints reach ⟨σv⟩ values of 3.7×10^{-26} cm^{3} s^{-1} for 1.5 TeV DM mass in the W^{+}W^{-} annihilation channel, and 1.2×10^{-26} cm^{3} s^{-1} for 0.7 TeV DM mass in the τ^{+}τ^{-} annihilation channel. With the H.E.S.S. Inner Galaxy Survey, ground-based γ-ray observations thus probe ⟨σv⟩ values expected from thermal-relic annihilating TeV DM particles.

Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433.

SS 433 is a microquasar, a stellar binary system that launches collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.) and found an energy-dependent shift in the apparent position of the gamma-ray emission from the parsec-scale jets. These observations trace the energetic electron population and indicate that inverse Compton scattering is the emission mechanism of the gamma rays. Our modeling of the energy-dependent gamma-ray morphology constrains the location of particle acceleration and requires an abrupt deceleration of the jet flow. We infer the presence of shocks on either side of the binary system, at distances of 25 to 30 parsecs, and that self-collimation of the precessing jets forms the shocks, which then efficiently accelerate electrons.

[The directed modification of Escherichia coli MG1655 to obtain histidine-producing mutants].

Strain MG 1655+hisGr hisL'-Delta, purR, which produces histidine with a weight yield of approximately 12% from glucose, was constructed through directed chromosomal modifications of the laboratory Escherichia coli strain MG 1655+, which has a known genome sequence. A feedback-resistant ATP-phosphoribosyl transferase encoded by the mutant hisGr (E271 K) was the main determinant of histidine production. A further increase in histidine production was achieved by the expression enhance of a mutant his operon containing hisGr through the deleting attenuator region (hisL'-Delta). An increase in the expression of the wildtype his operon did not result in histidine accumulation. Deletion of the transcriptional regulator gene purR increased the biomass produced and maintained the level of histidine production per cell under the fermentation conditions used.

Time-resolved hadronic particle acceleration in the recurrent nova RS Ophiuchi.

Recurrent novae are repeating thermonuclear explosions in the outer layers of white dwarfs, due to the accretion of fresh material from a binary companion. The shock generated when ejected material slams into the companion star's wind can accelerate particles. We report very-high-energy (VHE; [Formula: see text]) gamma rays from the recurrent nova RS Ophiuchi, up to 1 month after its 2021 outburst, observed using the High Energy Stereoscopic System (H.E.S.S.). The temporal profile of VHE emission is similar to that of lower-energy giga-electron volt emission, indicating a common origin, with a 2-day delay in peak flux. These observations constrain models of time-dependent particle energization, favoring a hadronic emission scenario over the leptonic alternative. Shocks in dense winds provide favorable environments for efficient acceleration of cosmic rays to very high energies.

Revealing x-ray and gamma ray temporal and spectral similarities in the GRB 190829A afterglow.

Gamma-ray bursts (GRBs), which are bright flashes of gamma rays from extragalactic sources followed by fading afterglow emission, are associated with stellar core collapse events. We report the detection of very-high-energy (VHE) gamma rays from the afterglow of GRB 190829A, between 4 and 56 hours after the trigger, using the High Energy Stereoscopic System (H.E.S.S.). The low luminosity and redshift of GRB 190829A reduce both internal and external absorption, allowing determination of its intrinsic energy spectrum. Between energies of 0.18 and 3.3 tera-electron volts, this spectrum is described by a power law with photon index of 2.07 ± 0.09, similar to the x-ray spectrum. The x-ray and VHE gamma-ray light curves also show similar decay profiles. These similar characteristics in the x-ray and gamma-ray bands challenge GRB afterglow emission scenarios.

Fourier transform ion cyclotron resonance mass spectrometer with coaxial multi-electrode cell ('O-trap'): first experimental demonstration.

The conceptual design of the O-trap Fourier transform ion cyclotron resonance (FT-ICR) cell addresses the speed of analysis issue in FT-ICR mass spectrometry. The concept of the O-trap includes separating the functions of ion excitation and detection between two different FT-ICR cell compartments. The detection compartment of the O-trap implements additional internal coaxial electrodes around which ions with excited cyclotron motion revolve. The expected benefits are higher resolving power and the lesser effect of the space charge. In this work we present the first experimental demonstration of the O-trap cell and its features, including the high ion transfer efficiency between two distinct compartments of an ICR cell after excitation of the coherent cyclotron motion. We demonstrate that utilization of the multiple-electrode detection in the O-trap provides mass resolving power enhancement (achieved over a certain time) equal to the order of the frequency multiplication. In an O-trap installed in a 5 T desk-top cryogen-free superconducting magnet, the resolving power of R = 80,000 was achieved for bradykinin [M + 2H](2+) (m/z 531; equivalent to 100,000 when recalculated for m/z 400) in 0.2 s analysis time (transient length), and R = 300,000 at m/z 531 for a 1 s transient. In both cases, detection on the third multiple of the cyclotron frequency was implemented. In terms of the acquisition speed at fixed resolving power, such performance is equivalent to conventional FT-ICR detection using a 15 T magnet.

[Modified method for the demonstration of argyrophilic proteins in the nucleolar organizer regions in paraffin sections].

The modified method of staining of argyrophilic nucleolar organizer regions (AgNORs) by silver nitrate is presented. This modification eliminates some disadvantages of an original technique. The method accelerates staining and prevents the precipitation of deposits.

[Gene yddG of Escherichia coli encoding the putative exporter of aromatic amino acids: constitutive transcription and dependence of the expression level on the cell growth rate].

Gene yddG of Escherichia coli encodes a protein of the inner membrane. Data obtained earlier demonstrated that under conditions of oversynthesis of aromatic amino acids, YddG promotes their export from E. coli cells. In this work, a method of primer extension was used to localize the P(yddG) promoter, which corresponds to E. coli promoters recognized by RNA polymerase in complex with sigma70 or sigma(S) subunits. By constructing a gene of the hybrid protein YddG'-LacZ at the intrinsic site of gene yddG location in the E. coli chromosome and analyzing the activity of beta-galactosidase in cells growing on laboratory media LB and M9, the constitutive type of yddG expression at a low level was demonstrated (the activity reached approximately 3 to 4% of the level of LacZ in E. coli wild-type cells under induction of the lac operon). The expression of yddG had a twofold increase under conditions of retarded cell growth upon the stress caused by the high NaCl content (0.6 M) or by the presence of phenylalanine excess quantities (> 1 mM) in the culture medium.

[2D [1H,13C] NMR study of carbon fluxes during glucose utilization by Escherichia coli MG1655].

Carbon fluxes through main pathways of glucose utilization in Escherichia coli cells--glycolysis, pentose phosphate pathway (PPP), and Enther-Doudoroff pathway (EDP)--were studied. Their ratios were analyzed in E. coli strains MG1655, MG1655(edd-eda), MG1655(zwf, edd-eda), and MG1655(pgi, edd-eda). It was shown that the carbon flux through glycolysis was the main route of glucose utilization, averaging ca. 80%. Inactivation of EDP did not affect growth parameters. Nevertheless, it altered carbon fluxes through the tricarboxylic acid cycles and energy metabolism in the cell. Inactivation of PPP decreased growth rate to a lesser degree than glycolysis inactivation.

[The clinical significance of immunohistochemically detectable Ki-67 protein in renal cell carcinoma].

Great attention is paid to renal cell carcinoma (RCC) due to the growth of its prevalence. This paper is dedicated to the matching of classic clinical and pathological prognostic factors to the character of the expression of proliferation marker Ki-67 in this kind of cancer. The proliferative activity was analyzed in 101 RCC cases by immunohistochemical assays using antibodies to Ki-67. In aggressive RCC and Fuhrman grade 3 to 4 tumors, Ki-67 level was found to be high more often. Besides, time to the appearance of remote metastases was significantly shorter, and total survival rate was significantly lower in RCC with high proliferative activity vs. low.

[Pleural metastases of renal carcinoma].

Metastases in renal carcinoma are diagnosed at initial diagnosis in 25% examinees. Traditional renal carcinoma has higher metastatic potential, is associated with worse survival of the patients compared to papillary cancer. We studied cytological characteristics of renal carcinoma metastases to the pleura in comparison with histological studies of the primary lesion using immunohistochemical findings. We examined cytologically pleural liquid in renal carcinoma metastases to the pleura in 6 patients (2.3% of carcinomatous pleuricies). High efficacy was shown by a cytocentrifuge CYTOSPIN-4. In 3 cases initial cancer was renal cell carcinoma, pleural exudation developed 2 years later, clear cell carcinoma appeared 6 years later and papillary cancer--10 years later. In the other 3 cases malignant cells were detected in new-onset cases. Renal carcinoma was diagnosed in one case. Cytological preparations were studied with identification of cytological signs typical for classic clear cell, granulocell and papillary renal cancer. Immunohistochemical examination of primary tumor lesion in the kidney discovered high proliferative activity of tumor cells by Ki-67 index to 5.28%. The tumors had solitary Bcl-2 positive cells. Expression of mutant p-53 took place in 0.93%. Her-2/neu hyperexpression was not found in the tumors of the above patients. Such immunohistochemical parameters point to poor prognosis. This is confirmed by renal carcinoma metastases to the pleura.

[Tuning of expression level of the genes of interest located in the bacterial chromosome].

The new method of construction of the set of E. coli clones, differing in the promoter strength upstream the gene of interest, has been developed and tested using native E. coli MG 1655 lacZ gene as the reporter. This method includes the construction of the promoter-carrying DNA fragment obtained by PCR with consensus P(tac) as a template and the primers that lead to randomization of 4 central nucleotides in the promoter "-35"-region, linking the obtained fragments with the selective marker (Cm(R)) followed by Red-driven integration of the resulted DNA fragments directly in E. coli MG1655 chromosome instead the native lacI-gene and promoter/operator region of lac-operon. Due to direct determination of LacZ-activity in the independently obtained clones-integrants, we have found 14 new promoters (from 44 = 256 possible variants) that differ in their strength up to 100 fold (LacZ-activity in the corresponding strains smoothly varies from 10(2) for the weakest tested promoter up to 10(4) Miller U detected for the initial P(tac)). Sequencing of obtained promoters revealed that randomization of three positions in the "-35"-region is sufficient to obtain representative promoter library that would decrease the total number of potential promoter variants from 256 up to 64. It seems probable that exploiting of the developed method leading to one-step construction the library of clones with varied expression of gene/operon of interest could be useful tool in the modem metabolic engineering for optimization of genes expression.

Ideal velocity focusing in a reflectron time-of-flight mass spectrometer.

A single-stage ion mirror in a time-of-flight (TOF) mass spectrometer (MS) can perform first order velocity focusing of ions initially located at a start focal plane while second order velocity focusing can be achieved using a double-stage reflectron. The situation is quite different when an ion source extraction field is taken into account. In this case which is common in any practical matrix-assisted laser desorption/ionization (MALDI) TOF-MS a single-stage reflectron, for example, cannot perform velocity focusing at all. In this paper an exact, analytic solution for an electric field inside a one-dimensional reflectron has been found to achieve universal temporal focusing of ions having an initial velocity distribution. The general solution is valid for arbitrary electric field distributions in the upstream (from the ion source to the reflectron) and downstream (from the reflectron to an ion detector) regions and in a decelerating part of the reflectron of a reflectron TOF mass spectrometer. The results obtained are especially useful for designing MALDI reflectron TOF mass spectrometers in which the initial velocity distribution of MALDI ions is the major limiting factor for achieving high mass resolution. Using analytical expressions obtained for an arbitrary case, convenient working formulas are derived for the case of a reflectron TOF-MS with a dual-stage extraction ion source. The special case of a MALDI reflectron TOF-MS with an ion source having a low acceleration voltage (or large extraction region) is considered. The formulas derived correct the effect of the acceleration regions in a MALDI ion source and after the reflectron before detecting ions.

The broad host range plasmid pLF1311 from Lactobacillus fermentum VKM1311.

The complete nucleotide sequence (2389 bp) of the cryptic plasmid pLF1311 from Lactobacillus fermentum VKM1311 was determined. DNA sequence analysis revealed the putative coding regions for a replicative protein (RepB), its repressor (RepA) and double-stranded (dso) and single-stranded (sso) origins. pLF1311 belongs to the pE194 family of rolling circle-replicating plasmids. A derivative of pLF1311 that contains the cat gene of plasmid pC194 of Staphylococcus aureus and the oriT of RP4 was constructed and transferred by conjugative mobilization from Escherichia coli to various Gram-positive bacteria. The stable maintenance of this derivative was shown in some strains of Lactobacillus, Lactococcus, Enterococcus and Bacillus under non-selective conditions.

Injection of externally generated ions into an increasing trapping field of a quadrupole ion trap mass spectrometer.

Trapping ions injected into a quadrupole ion trap (QIT) by increasing the trapping r.f. voltage on a ring electrode is an effective and widely recognized method of interfacing an ion trap with pulsed ion sources such as matrix-assisted laser desorption/ionization (MALDI). In this paper, the problem of mass discrimination during the injection and trapping of ions by the increasing r.f. field was studied both experimentally and by numerical simulation using SIMION software. For a MALDI/QIT interface design with a remote external ion source described here, experiments with polyethylene glycol (PEG 1000 and PEG 1500) showed little mass discrimination for trapping ions in a wide mass range (500-2000 Dn) for a broad range of experimental conditions, which include kinetic energies of 5-40 eV for the injected ions and an r.f. voltage of 400-4000 Vo-p amplitude ramped at a rate of 30-140 Vo-p mus-1. In the numerical simulation, complex and sharp dependences of the trapping efficiency on the phase of the r.f. voltage and initial kinetic energy of ions were observed. However, after averaging over the r.f. phase and over a reasonable range of kinetic energy, the simulation resulted in relatively constant and high values for the trapping efficiency (normally 0.2-0.3) for any mass and kinetic energy considered, which are consistent with the weak sensitivity to injection parameters observed in the experiment. A simple model for the qualitative description of ion injection and trapping is suggested that relies on phase interaction of injected ions with the r.f. field rather than on collisions with the buffer gas molecules to decrease the ion kinetic energy.

A quadrupole ion trap/time-of-flight mass spectrometer with a parabolic reflectron.

A matrix-assisted laser desorption/ionization-quadrupole ion trap/reflectron time-of-flight (MALDI-QIT/reTOF) mass spectrometer design and its operation in both normal and tandem mass spectrometric modes are described. A parabolic reflectron was found to be capable of providing mass resolution of 5000 for an initial ion energy distribution ranging over a 50% energy interval of the entire reflectron energy range. The sensitivity, ion isolation and fragmentation efficiency in the MALDI-QIT/reTOF instrument were close to those observed in the MALDI/QIT mass spectrometer. The mass resolution was shown to depend on the extraction field potentials, the r.f. trapping voltage amplitude and the phase of shutting down the r.f. voltage before extraction. At values of qs < 0.3-0.4 the mass resolution does not depend on the ion mass, is in a range of 1000-1400 and is governed by the extraction voltages and the ion temperature before extraction, the latter shown to be in the range 1180-1690 K. The variation of the mass resolution for ions at values of qs > 0.4 is irregular but normally it is lower than that for ions having lower qs values. Mass spectral line positions shifted when the trapping voltage before extraction was varied. The line shifts were larger for lower mass ions and were comparable to the line widths in the case of very low masses.

A new focusing ultrasonic transducer and two foci acoustic lens for acoustic microscopy.

The textured piezoelectric film of a new organic-based material produced by vapor deposition was used as an active element of a focusing ultrasonic transducer. The transducer exhibits near theoretical lateral and axial resolution, unipolar pulse response to a step voltage, and 30 dB insertion losses in an octave frequency band. The transducer is acoustically transparent over a wide frequency range and can be fabricated on a concave spherical surface of the standard acoustic lens. The resulting double transducer and two foci acoustic lens are capable of improving the quality of the surface structure imaging or of being used in continuous wave reflection acoustic microscopy.

[Structural and functional organization of the transposon Tn2555 carrying saccharose utilization genes]. / Strukturnaia i funktsional'naia organizatsiia transpozoma Tn2555, nesushchego geny utilizatsii sakharozy.

Transposon Tn2555 was isolated from a clinical E. coli strain carries the genes for sucrose utilization. Previously it was shown that Tn2555 is very unstable and undergoes structural rearrangements with a high frequency. Several deletion derivatives of Tn2555 and one with an inversion of the internal segment were found. They form the Tn2555 transposon family. This paper describes further structural and functional analysis of Tn2555. In the course of the experiments on pBR325 (Mob-) mobilization by conjugative RP4 derivatives, containing Tn2555 family elements, it was found, that all of them induce cointegrate formation. Some of these cointegrates were able to dissociate in rec+ and recA E. coli cells. Restriction endonuclease analysis of the resulting plasmids have shown, that among them were the end products of the Tn2555 transposition from RP4 to pBR325. Besides, the pBR325 derivatives, containing a discrete DNA segment of approximately 800 b.p., originating from Tn2555, were found. The segment can transpose from pBR325 to RP4 indicating that it is an insertion sequence. This new IS-element was designated IS286. The size and the genetic properties of IS286 resemble those of the IS1 element. However restriction analysis and Southern hybridization data show no significant homology between IS286 and IS1. It was found that the Tn2555 family elements are flanked by directly repeated IS286. One of them (Tn2555.3) contains an additional copy of IS286 in its internal region.