Cryptogamic Botany New or interesting species of Ascobolus and Saccobolus in the USSR

SUMMARY In the study of coprophilous Discomycetes 17 interesting species from the genera Ascobolus and Saccobolus have been found on samples of dung of different animals, on soil and OH plant rcmains. Two of tlieniAscobolus ursinus Prokhorov, sp. nov. and Saccobolus mìnimoides, Prokhorov sp. nov. are described as new. Other species of these genera are rare or seldom collected ones. The most northern locality A. scatigenus has been detected in naturai conditions

Detection of synchronization from univariate data using wavelet transform

A method is proposed for detecting from univariate data the presence of synchronization of a self-sustained oscillator by external driving with varying frequency. The method is based on the analysis of difference between the oscillator instantaneous phases calculated using continuous wavelet transform at time moments shifted by a certain constant value relative to each other. We apply our method to a driven asymmetric van der Pol oscillator, experimental data from a driven electronic oscillator with delayed feedback and human heartbeat time series. In the latest case, the analysis of the heart rate variability data reveals synchronous regimes between the respiration and slow oscillations in blood pressure.Comment: 10 pages, 9 figure

X-ray polarimetry reveals the magnetic field topology on sub-parsec scales in Tycho's supernova remnant

Supernova remnants are commonly considered to produce most of the Galactic cosmic rays via diffusive shock acceleration. However, many questions about the physical conditions at shock fronts, such as the magnetic-field morphology close to the particle acceleration sites, remain open. Here we report the detection of a localized polarization signal from some synchrotron X-ray emitting regions of Tycho's supernova remnant made by the Imaging X-ray Polarimetry Explorer. The derived polarization degree of the X-ray synchrotron emission is 9+/-2% averaged over the whole remnant, and 12+/-2% at the rim, higher than the 7-8% polarization value observed in the radio band. In the west region the polarization degree is 23+/-4%. The X-ray polarization degree in Tycho is higher than for Cassiopeia A, suggesting a more ordered magnetic-field or a larger maximum turbulence scale. The measured tangential polarization direction corresponds to a radial magnetic field, and is consistent with that observed in the radio band. These results are compatible with the expectation of turbulence produced by an anisotropic cascade of a radial magnetic-field near the shock, where we derive a magnetic-field amplification factor of 3.4+/-0.3. The fact that this value is significantly smaller than those expected from acceleration models is indicative of highly anisotropic magnetic-field turbulence, or that the emitting electrons either favor regions of lower turbulence, or accumulate close to where the magnetic-field orientation is preferentially radially oriented due to hydrodynamical instabilities.Comment: 31 pages, 7 figures, 3 tables. Accepted for publication in ApJ. Revised versio

Magnetic structures and turbulence in SN 1006 revealed with imaging X-ray polarimetry

Young supernova remnants (SNRs) strongly modify surrounding magnetic fields, which in turn play an essential role in accelerating cosmic rays (CRs). X-ray polarization measurements probe magnetic field morphology and turbulence at the immediate acceleration site. We report the X-ray polarization distribution in the northeastern shell of SN1006 from a 1 Ms observation with the Imaging X-ray Polarimetry Explorer (IXPE). We found an average polarization degree of $22.4\pm 3.5\%$ and an average polarization angle of $-45.4\pm 4.5^\circ$ (measured on the plane of the sky from north to east). The X-ray polarization angle distribution reveals that the magnetic fields immediately behind the shock in the northeastern shell of SN 1006 are nearly parallel to the shock normal or radially distributed, similar to that in the radio observations, and consistent with the quasi-parallel CR acceleration scenario. The X-ray emission is marginally more polarized than that in the radio band. The X-ray polarization degree of SN 1006 is much larger than that in Cas A and Tycho, together with the relatively tenuous and smooth ambient medium of the remnant, favoring that CR-induced instabilities set the turbulence in SN 1006 and CR acceleration is environment-dependent.Comment: 15 pages, 4 Figures, 2 Tables; accepted for publication in The Astrophysical Journa

Dynamics of Oligomer Formation by Denatured Carbonic Anhydrase II

Aggregation and subsequent development of protein deposition diseases originate from conformational changes in corresponding amyloidogenic proteins. Many proteins unrelated to amyloidoses also fibrillate at the appropriate conditions. These proteins serve as a model for studying the processes of protein misfolding, oligomerization and fibril formation. The accumulated data support the model where protein fibrillogenesis proceeds via the formation of a relatively unfolded amyloidogenic conformation. The urea-induced unfolding of bovine carbonic anhydrase II, BCA II, is characterized by a combination of high-resolution NMR, circular dichroism spectroscopy and small angle X-ray scattering. It is shown that the formation of associates of protein molecules in complex with solvent (water and urea), APS, takes place in the presence of 4–6 M urea. The subsequent increase in urea concentration to 8 M is accompanied by a disruption of APS and leads to a complete unfolding of a protein molecule. Analysis of BCA II self-association in the presence of 4.2 M urea revealed that APS are relatively large mostly β-structural blocks with the averaged molecular mass of 190–220 kDa. This work also demonstrates some novel NMR-based methodological approaches that provide useful information on protein self-association

Molecular Mechanisms of The Anomalous Thermal Aggregation of Green Fluorescent Protein

The peculiarities of thermal denaturation and interaction with water of the cycle-3 mutant of green fluorescent protein (GFP) were analyzed by NMR techniques and compared with those of bovine carbonic anhydrase II (BCA-II). Irreversible thermal denaturation was accompanied by massive GFP aggregation with no detectable accumulation of soluble denatured protein. Analysis of the spin diffusion data suggested that the internal part of the GFP β-can is involved in intensive interactions with water molecules. As a result, at high temperatures, the GFP structure does not unfold but rather breaks, consequently leading to enhanced protein aggregation. This is very different from typical BCA-II behavior

Dynamics of 0.1 Hz Oscillations Synchronization in Cardiovascular System during the Treatment of Acute Myocardial Infarction Patients

Aim: The aim was the studying of synchronization between 0.1 Hz oscillations in heart rate (HR) and plethysmographic peripheral microcirculation (PM) in acute myocardial infarction (AMI) patients and in healthy subjects. Material and Method: 12 healthy volunteers aged 26±5 years and 125 patients with AMI aged 65±9 years were involved in the study. Simultaneous registration of electrocardiogram and photoplethysmogram were performed during 10 min. In AMI patients the signals were recorded twice: the first record was done during 3-5 days after AMI, the second record was done during the third week after AMI. Phase differences between HR and PM oscillations were used to measure the degree of synchronization (S). Data are submitted as medians with inter-quartile ranges (25%, 75%). Results: S was 65.8% (50.5%; 79.5%) in healthy subjects whereas in AMI patients at the first week after AMI S was 16.3% (9.4%; 24.6%) (p<0.001). In records made at the third week after AMI index S was 18.4% (11.2%; 28.2%). Two groups of AMI patients were identified on the basis of individual S dynamics. In 100 AMI patients no dynamics of S was observed during the observation period and in 25 AMI patients the increase of S was observed. The group of AMI patients with increase of S had greater HR values during the first week after AMI. Conclusion: The index S of synchronization of 0.1 Hz oscillations in HR and PM appears to be a sensitive indicator of autonomic control dynamic disturbances in AMI patients

High-resolution NMR Structure of a Zn2+-containing Form of the Bacteriophage T5 L-alanyl-D-glutamate Peptidase

This paper represents the spatial solution structure of the Zn2+-containing form of the bacteriophage T5 L-alanyl-D-glutamate peptidase (EndoT5-Zn2+). The core of this α + β protein is formed by three α-helices (residues 7–15, 20–30, and 87–104) and a β-sheet containing three β-strands (residues 35–39, 71–76, and 133–135). The protein has two short loops (residues 16–19 and 31–34), a medium-length loop (residues 77–86) containing a short β-hairpin (residues 77–82), and two long loops (residues 40–70 and 105–132). The long loops include a stable 310-helix (residues 66–68) and labile α-helices 46–53 and 113–117. Catalytic Zn2+-binding site is represented by three amino acid residues, His66, Asp73, and His133. The cation-binding His residues are located near the foundations of the long loops, whereas Asp73 is positioned in the middle of the core β-sheet. The catalytic center localization contributes to the stabilization of the entire molecule, with Zn2+-binding playing a key role in the folding of this protein

Solution Structure and Dynamics of The Chimeric SH3 Domains, SHH- and ShA-“Bergeracs”

Two chimeric proteins, SHН and SHA of the “SH3-Bergerac” family (where the β-turn N47D48 in spectrin SH3 domain was substituted for KITVNGKTYE or KATANGKTYE sequences, respectively), were analyzed by high-resolution NMR to resolve their spatial structures and to analyze their dynamics. Although the presence of a stable β-hairpin in the region of the insertion was confirmed, the introduced extension of the polypeptide chain in SHН (∼ 17%) practically did not affect the total molecule topology. Interestingly, the introduced β-hairpin had higher mobility in comparison with other protein regions. Finally, we performed a disorder prediction with the PONDR® VSL2 algorithm and discovered that the inserted β-hairpin in both SHH and SHA proteins exhibited significant propensity for intrinsic disorder and therefore for high mobility. In agreement with the experimental data, the predisposition for the increased intramolecular mobility was noticeably higher in SHA