Differential Expression of Stress Adaptation Genes in a Diatom Ulnaria acus under Different Culture Conditions

Diatoms are a group of unicellular eukaryotes that are essential primary producers in aquatic ecosystems. The dynamic nature of their habitat necessitates a quick and specific response to various stresses. However, the molecular mechanisms of their physiological adaptations are still underexplored. In this work, we study the response of the cosmopolitan freshwater diatom Ulnaria acus (Bacillariophyceae, Fragilariophycidae, Licmophorales, Ulnariaceae, Ulnaria) in relation to a range of stress factors, namely silica deficiency, prolonged cultivation, and interaction with an algicidal bacterium. Fluorescent staining and light microscopy were used to determine the physiological state of cells under these stresses. To explore molecular reactions, we studied the genes involved in the stress response-type III metacaspase (MC), metacaspase-like proteases (MCP), death-specific protein (DSP), delta-1-pyrroline-5-carboxylate dehydrogenase (ALDH12), and glutathione synthetase (GSHS). We have described the structure of these genes, analyzed the predicted amino acid sequences, and measured their expression dynamics in vitro using qRT-PCR. We demonstrated that the expression of UaMC1, UaMC3, and UaDSP increased during the first five days of silicon starvation. On the seventh day, it was replaced with the expression of UaMC2, UaGSHS, and UaALDH. After 45 days of culture, cells stopped growing, and the expression of UaMC1, UaMC2, UaGSHS, and UaDSP increased. Exposure to an algicidal bacterial filtrate induced a higher expression of UaMC1 and UaGSHS. Thus, we can conclude that these proteins are involved in diatoms' adaptions to environmental changes. Further, these data show that the molecular adaptation mechanisms in diatoms depend on the nature and exposure duration of a stress factor.

The first probe of a FLASH proton beam by PET

The recently observed FLASH effect related to high doses delivered with high rates has the potential to revolutionize radiation cancer therapy if promising results are confirmed and an underlying mechanism understood. Comprehensive measurements are essential to elucidate the phenomenon. We report the first-ever demonstration of measurements of successive in-spill and post-spill emissions of gammas arising from irradiations by a FLASH proton beam. A small positron emission tomography (PET) system was exposed in an ocular beam of the Proton Therapy Center at MD Anderson Cancer Center to view phantoms irradiated by 3.5 × 1010protons with a kinetic energy of 75.8 MeV delivered in 101.5 ms-long spills yielding a dose rate of 164 Gy s-1. Most in-spill events were due to prompt gammas. Reconstructed post-spill tomographic events, recorded for up to 20 min, yielded quantitative imaging and dosimetric information. These findings open a new and novel modality for imaging and monitoring of FLASH proton therapy exploiting in-spill prompt gamma imaging followed by post-spill PET imaging.

Chronic Administration of Non-Constitutive Proteasome Inhibitor Modulates Long-Term Potentiation and Glutamate Signaling-Related Gene Expression in Murine Hippocampus

Proteasomes degrade most intracellular proteins. Several different forms of proteasomes are known. Little is known about the role of specific proteasome forms in the central nervous system (CNS). Inhibitors targeting different proteasome forms are used in clinical practice and were shown to modulate long-term potentiation (LTP) in hippocampal slices of untreated animals. Here, to address the role of non-constitutive proteasomes in hippocampal synaptic plasticity and reveal the consequences of their continuous inhibition, we studied the effect of chronic administration of the non-constitutive proteasome inhibitor ONX-0914 on the LTP induced by two different protocols: tetanic stimulation and theta-burst stimulation (TBS). Both the tetanus- and TBS-evoked potentiation contribute to the different forms of hippocampal-dependent memory and learning. Field-excitatory postsynaptic potentials (fEPSPs) in hippocampal slices from control animals and animals treated with DMSO or ONX-0914 were compared. LTP induced by the TBS was not affected by ONX-0914 administration; however, chronic injections of ONX-0914 led to a decrease in fEPSP slopes after tetanic stimulation. The observed effects correlated with differential expression of genes involved in synaptic plasticity, glutaminergic synapse, and synaptic signaling. Obtained results indicate that non-constitutive proteasomes are likely involved in the tetanus-evoked LTP, but not the LTP occurring after TBS, supporting the relevance and complexity of the role of specific proteasomes in synaptic plasticity, memory, and learning.

Planar Gas Expansion under Intensive Nanosecond Laser Evaporation into Vacuum as Applied to Time-of-Flight Analysis

A computational investigation of the dynamics of gas expansion due to intense nanosecond laser evaporation into vacuum has been carried out. The problem is solved in a one-dimensional approximation, which simplifies calculations and at the same time allows one to analyze the main features of the expansion dynamics. For analysis we use three different approaches. Two of them are based on kinetic analysis via the direct simulation Monte Carlo (DSMC) method and numerical solution of the model Bhatnagar-Gross-Krook (BGK) equation. The third one focuses on derivation of an analytical continuum solution. Emphasis is placed on the analysis of the velocity distribution function and the average energy of particles passing through the time-of-flight detector on the normal to the evaporation surface, which is important for interpreting experimental measurements. The formulated problem is quite difficult as the considered flow is time-dependent, contains discontinuities in boundary conditions and involves large variations of local Knudsen numbers as well as steep gradients of the velocity distribution function. Data were obtained on the particle energy in the time-of-flight distribution for the range of regimes from the free molecular flow to continuum one. The maximum attainable average energy of particles in the time-of-flight distribution is determined. The non-monotonicity of the energy increase was found, which is explained based on analysis of the velocity distribution of particles.

Data on FTIR spectra of the clays KGa-1b and STx-1b and their mixtures at different moistures

Kaolinite and smectite are among the main soil-forming minerals, and therefore their properties are constantly being refined. This article provides data on the IR spectra of the clays KGa-1b and STx-1b containing 96% and 67% of those minerals [1], and their mixtures in equal mass proportions at different moisture contents. These data were used in the article “Study of hydration of kaolinite and montmorillonite mixture by IR spectroscopy” [2], to study the dynamics of the formation of water layers on the surface of clay particles. The data presented can be used to test experimental methods for studying the adsorption properties of mixtures, and to create new laboratory methods for determining the plastic properties of soils [3]. In addition, the data presented can be used to verify theoretical approximations and computer models for calculating the structure and electronic properties of minerals and their mixtures [4].

Measurement of Lepton-Jet Correlation in Deep-Inelastic Scattering with the H1 Detector Using Machine Learning for Unfolding

The first measurement of lepton-jet momentum imbalance and azimuthal correlation in lepton-proton scattering at high momentum transfer is presented. These data, taken with the H1 detector at HERA, are corrected for detector effects using an unbinned machine learning algorithm (multifold), which considers eight observables simultaneously in this first application. The unfolded cross sections are compared with calculations performed within the context of collinear or transverse-momentum-dependent factorization in quantum chromodynamics as well as Monte Carlo event generators.

Responses of hepatic biotransformation and antioxidant enzymes in Japanese medaka (Oryzias latipes) exposed to humic acid

Humic substances, a major component of natural organic matter in surface waters, can induce biotransformation enzyme activities and influence antioxidant defense in fish. The study aimed to provide a molecular basis for the stress responses, the synthesis of biotransformation, and antioxidant enzymes in particular. Adult medaka fish (Hd-rR strain) were exposed to environmentally relevant concentrations of humic acid for 96 h. The actual humic acid concentrations in water were determined photometrically and expressed as organic carbon concentrations. Liquid chromatography with tandem mass spectrometry was used for protein profile analysis of medaka liver samples. The relative amount of isozymes was determined using the label-free quantification approach. Hepatic biotransformation enzyme activities were measured as well. Thus, ethoxyresorufin-O-deethylase activity showed a pronounced induction at the highest tested concentration (9.4 mg C/L). Various biotransformation and antioxidant isozymes responded to humic acid differently, reflecting a balanced interplay of proteins that ensures the metabolism of humic acid in fish liver. Some isozymes were not affected by humic acid. The study provides new insight into the molecular mechanisms of the fish stress response to the humic acid-related challenge.

Microanatomy and ultrastructure of kidney interstitial cells and nephron in brown trout (Salmo trutta Linnaeus, 1758) at different stages of the life cycle

The study focuses on the microanatomy and ultrastructural changes in the trunk kidney interstitium cells and nephrons in parr, smolt and spawning brown trout Salmo trutta Linnaeus, 1758 sampled in Luga River and Solka River, the tributaries of the Baltic Sea. Regardless of the type of cells or their structure, there were changes in their areas and the number and structure of organelles responsible for the transport, synthetic and energetic function of cells. Our data on the morphology of the nephron combined with data on its physiology suggest a fundamental change in kidney function during the parr-smolt transformation before migration; this could be a preadaptation for a successful life in saltwater where urine output is sharply reduced. Thus, detected structural features of the trunk kidney in brown trout S. trutta are cytological markers of the migration process. The numbers of lymphocytes, neutrophils and eosinophils with segmented nuclei increased from parr to smolts and then to spawners; only monotypic specific granules in neutrophils were found in smolts and spawners. Cells with radially arranged vesicles were described for the first time in brown trout S. trutta renal interstitium. Their origin has not yet been established. The shape of these cells changed from spherical to trihedral during fish maturation. All the above ultrastructural changes of renal interstitium cells could be considered cytological markers of cell maturity.

The TZM-bl Reporter Cell Line Expresses Kynureninase That Can Neutralize 2F5-like Antibodies in the HIV-1 Neutralization Assay

Induction of broadly neutralizing antibodies targeting ectodomain of the transmembrane (TM) glycoprotein gp41 HIV-1 provides a basis for the development of a universal anti-viral vaccine. The HeLa cell-derived TZM-bl reporter cell line is widely used for the estimation of lentiviruses neutralization by immune sera. The cell line is highly permissive to infection by most strains of HIV, SIV, and SHIV. Here we demonstrated that TZM-bl cells express a 48 kDa non-glycosylated protein (p48) recognized by broadly neutralizing monoclonal antibody (mAb) 2F5 targeting the ELDKWA (aa 669–674) epitope of gp41TM of HIV-1. A significant amount of p48 was found in the cell supernatant. The protein was identified as human kynureninase (KYNU), which has the ELDKWA epitope. The protein is further called “p48 KYNU”. The HIV-1 neutralization by mAb 2F5 and 4E10 in the presence of p48KYNU was tested on Jurkat and TZM-bl cells. It was demonstrated that p48KYNU reduces neutralization by 2F5-like antibodies, but it has almost no effect on mAb 4E10. Therefore, p48KYNU can attenuate HIV-1 neutralization by 2F5-like antibodies and hence create false-negative results. Thus, previously tested immune sera that recognized the ELDKWA-epitope and demonstrated a “weak neutralization” of HIV-1 in TZM-bl assay should be reevaluated.

Mechanisms for destabilisation of RNA viruses at air-water and liquid-liquid interfaces

Understanding the interactions between viruses and surfaces or interfaces is important, as they provide the principles underpinning the cleaning and disinfection of contaminated surfaces. Yet, the physics of such interactions is currently poorly understood. For instance, there are longstanding experimental observations suggesting that the presence of air-water interfaces can generically inactivate and kill viruses, yet the mechanism underlying this phenomenon remains unknown. Here we use theory and simulations to show that electrostatics may provide one such mechanism, and that this is very general. Thus, we predict that the electrostatic free energy of an RNA virus should increase by several thousands of k_BT as the virion breaches an air-water interface. We also show that the fate of a virus approaching a generic liquid-liquid interface depends strongly on the detailed balance between interfacial and electrostatic forces, which can be tuned, for instance, by choosing different media to contact a virus-laden respiratory droplet. Tunability arises because both the electrostatic and interfacial forces scale similarly with viral size. We propose that these results can be used to design effective strategies for surface disinfection.

We know that air-water interfaces can generically inactivate viruses, but the mechanisms behind this observation are unclear. Here the authors use simulations to uncover those mechanisms and find that the electrostatic repulsive free energy of an RNA virus increases by several thousands of kBT as it approaches an air-water interface, providing a mechanism for viral destabilization which may induce inactivation.

Combinatorial invariant for Morse-Smale diffeomorphisms on surfaces with orientable heteroclinic

In this paper, we consider a class of orientation-preserving Morse-Smale diffeomorphisms defined on an orientable surface. The papers by Bezdenezhnykh and Grines showed that such diffeomorphisms have a finite number of heteroclinic orbits. In addition, the classification problem for such diffeomorphisms is reduced to the problem of distinguishing orientable graphs with substitutions describing the geometry of a heteroclinic intersection. However, such graphs generally do not admit polynomial discriminating algorithms. This article proposes a new approach to the classification of these cascades. For this, each diffeomorphism under consideration is associated with a graph that allows the construction of an effective algorithm for determining whether graphs are isomorphic. We also identified a class of admissible graphs, each isomorphism class of which can be realized by a diffeomorphism of a surface with an orientable heteroclinic. The results obtained are directly related to the realization problem of homotopy classes of homeomorphisms on closed orientable surfaces. In particular, they give an approach to constructing a representative in each homotopy class of homeomorphisms of algebraically finite type according to the Nielsen classification, which is an open problem today.

COMPENSATION FOR THE AGE GAP IN THE DEVELOPMENT OF SPEED ABILITIES IN SCHOOLCHILDREN WITH HEARING IMPAIRMENT AGED 11–12 YEARS BASED ON THE MEANS OF ATHLETICS

Aim. The article aims to organize and implement inclusive physical education of students with hearing impairment, as well as to experimentally justify the use of athletics-oriented tools for speed abilities based on an individual approach. Materials and methods. The experiment involved 23 students with hearing deprivation, 11 of them from the Special secondary boarding school for deaf and hard-of-hearing children and 12 from School No 24 implementing inclusive education. The first group followed a standard curriculum for these types of educational organizations, the second group used an experimental method of working in inclusive classes with healthy peers. Special testing was applied to determine the level of speed abilities, and a variable scheme was used to apply an individual approach. Methods of mathematical statistics were used to process the results of the study. The calculations were performed in Microsoft Excel 2007. Results. The experimental method for compensating the age gap in the development of speed abilities in schoolchildren with hearing impairment is a developed and implemented system for conducting classes in inclusive education. The high-level indicators obtained are the result of a set of measures carried out at the preliminary and main stage of the study. This type of training represents a systematic approach to inclusive physical education and provides the development of a multi stage alternative education with comprehensive support. Conclusion. As a result of applying the method in the experimental group, the results of participants with hearing impairment began to correspond with those of healthy peers. Moreover, the concomitant influence increased the indicators of physical fitness, there was a complex positive effect on the motor and emotional spheres.

Phase variation in pneumococcal populations during carriage in the human nasopharynx

Streptococcus pneumoniae is one of the world's leading bacterial pathogens, responsible for pneumonia, septicaemia and meningitis. Asymptomatic colonisation of the nasopharynx is considered to be a prerequisite for these severe infections, however little is understood about the biological changes that permit the pneumococcus to switch from asymptomatic coloniser to invasive pathogen. A phase variable type I restriction-modification (R-M) system (SpnIII) has been linked to a change in capsule expression and to the ability to successfully colonise the murine nasopharynx. Using our laboratory data, we have developed a Markov change model that allows prediction of the expected level of phase variation within a population, and as a result measures when populations deviate from those expected at random. Using this model, we have analysed samples from the Experimental Human Pneumococcal Carriage (EHPC) project. Here we show, through mathematical modelling, that the patterns of dominant SpnIII alleles expressed in the human nasopharynx are significantly different than those predicted by stochastic switching alone. Our inter-disciplinary work demonstrates that the expression of alternative methylation patterns should be an important consideration in studies of pneumococcal colonisation.

Normal and pathological gait classification LSTM model

Computer vision-based clinical gait analysis is the subject of permanent research. However, there are very few datasets publicly available; hence the comparison of existing methods between each other is not straightforward. Even if the test data are in an open access, existing databases contain very few test subjects and single modality measurements, which limit their usage. The contributions of this paper are three-fold. First, we propose a new open-access multi-modal database acquired with the Kinect v.2 camera for the task of gait analysis. Second, we adapt to use the skeleton joint orientation data to calculate kinematic gait parameters to match golden-standard MOCAP systems. We propose a new set of features based on 3D low-limbs flexion dynamics to analyze the symmetry of a gait. Third, we design a Long-Short Term Memory (LSTM) ensemble model to create an unsupervised gait classification tool. The results show that joint orientation data provided by Kinect can be successfully used in an inexpensive clinical gait monitoring system, with the results moderately better than reported state-of-the-art for three normal/pathological gait classes.

Anomalies in the valve morphogenesis of the centric diatom alga Aulacoseira islandica caused by microtubule inhibitors

Of all unicellular organisms possessing a cell wall, diatoms are the most adept at micro- and nanoscale embellishment of their frustules. Elements of their cell walls are formed inside the cell under cytoskeletal control. In this work, we used laser scanning microscopy and electron microscopy to describe the major stages of cell wall formation in the centric diatom algae Aulacoseira islandica and to study the effect of various microtubule inhibitors on the morphogenesis of frustule elements. Our results show that colchicine inhibits karyokinesis and cytokinesis in A. islandica colonies. In contrast, valve morphogenesis is changed, rather than inhibited altogether. In normal cells, this process starts simultaneously in both daughter cells, beginning with the formation of two adjacent discs that later become valve faces and connecting spines. Under colchicine treatment, however, the cleavage furrow is blocked and a single lateral valve forms on the side of the cylindrical frustule. As a result, a single hollow pipe forms instead of two separate drinking glass-shaped frustules; such pipes can form up to 35% of all forming frustules. Colchicine inhibits the formation of connecting spines, whereas paclitaxel causes spines to form a complex, branching shape. At the same time, inhibitors do not affect the formation of areolae (openings) in the frustule. We discuss the possibility that various processes of the diatom frustule morphogenesis are controlled by two different mechanisms: membrane-related micromorphogenesis and cytoskeleton-mediated macromorphogenesis.

Determination of the strong coupling constant α s ( m Z ) in next-to-next-to-leading order QCD using H1 jet cross section measurements: H1 Collaboration

The strong coupling constant α s is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic ep scattering (DIS) measured at HERA by the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value ofα s ( m Z ) at the Z-boson mass m Z are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to beα s ( m Z ) = 0.1157 ( 20 ) exp ( 29 ) th . Complementary,α s ( m Z ) is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The valueα s ( m Z ) = 0.1142 ( 28 ) tot obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.

Synergistic suppression of t(8;21)-positive leukemia cell growth by combining oridonin and MAPK1/ERK2 inhibitors

One of the most common chromosomal translocations in acute myeloid leukemia is t(8;21)(q22;q22), which results in the appearance of abnormal transcripts encoding for the fusion protein RUNX1-ETO. Therefore, this oncoprotein is considered to be a pertinent and promising target for treating t(8;21) leukemia. Previously, we have shown that downregulation of RUNX1-ETO leads to activation of intracellular signaling pathways enhancing cell survival and determined that the protein ERK2 can mediate activation of most of these pathways. Here we used a combination of oridonin (natural tetracycline diterpenoid), which has been shown to exhibit anti-RUNX1-ETO activity, and ERK2 kinase inhibitors. We found that treatment of leukemic t(8;21)-positive Kasumi-1 cells with oridonin cause decrease of phosphorylated ERK1/2. Treatment of these cells with ERK2 inhibitors makes them more sensitive to RUNX1-ETO inhibition with oridonin. Therefore we postulate that simultaneous inhibition of RUNX1-ETO and ERK2 cause synergistic effect on survival of leukemic cells.

Iterative reconstruction of SiPM light response functions in a square-shaped compact gamma camera

Compact gamma cameras with a square-shaped monolithic scintillator crystal and an array of silicon photomultipliers (SiPMs) are actively being developed for applications in areas such as small animal imaging, cancer diagnostics and radiotracer guided surgery. Statistical methods of position reconstruction, which are potentially superior to the traditional centroid method, require accurate knowledge of the spatial response of each photomultiplier. Using both Monte Carlo simulations and experimental data obtained with a camera prototype, we show that the spatial response of all photomultipliers (light response functions) can be parameterized with axially symmetric functions obtained iteratively from flood field irradiation data. The study was performed with a camera prototype equipped with a 30  ×  30  ×  2 mm³ LYSO crystal and an 8  ×  8 array of SiPMs for 140 keV gamma rays. The simulations demonstrate that the images, reconstructed with the maximum likelihood method using the response obtained with the iterative approach, exhibit only minor distortions: the average difference between the reconstructed and the true positions in X and Y directions does not exceed 0.2 mm in the central area of 22  ×  22 mm² and 0.4 mm at the periphery of the camera. A similar level of image distortions is shown experimentally with the camera prototype.

Nonlinear elastic instability in channel flows at low Reynolds numbers

It is presently believed that flows of viscoelastic polymer solutions in geometries such as a straight pipe or channel are linearly stable. Here we present experimental evidence that such flows can be nonlinearly unstable and can exhibit a subcritical bifurcation. Velocimetry measurements are performed in a long, straight microchannel; flow disturbances are introduced at the entrance of the channel system by placing a variable number of obstacles. Above a critical flow rate and a critical size of the perturbation, a sudden onset of large velocity fluctuations indicates the presence of a nonlinear subcritical instability. Together with the previous observations of hydrodynamic instabilities in curved geometries, our results suggest that any flow of polymer solutions becomes unstable at sufficiently high flow rates.

BDNF-restricted knockout mice as an animal model for aggression

Mice with global deletion of one brain-derived neurotrophic factor (BDNF) allele or with forebrain-restricted deletion of both alleles show elevated aggression, but this phenotype is accompanied by other behavioral changes, including increases in anxiety and deficits in cognition. Here we performed behavioral characterization of conditional BDNF knockout mice generated using a Cre recombinase driver line, KA1-Cre, which expresses Cre in few areas of brain: highly at hippocampal area CA3 and moderately in dentate gyrus, cerebellum and facial nerve nucleus. The mutant animals exhibited elevated conspecific aggression and social dominance, but did not show changes in anxiety-like behaviors assessed using the elevated plus maze and open field test. There were no changes in depression-like behaviors tested in the forced swim test, but small increase in immobility in the tail suspension test. In cognitive tasks, mutants showed normal social recognition and normal spatial and fear memory, but exhibited a deficit in object recognition. Thus, this knockout can serve as a robust model for BDNF-dependent aggression and object recognition deficiency.

HIV-1 reverse transcriptase artificially targeted for proteasomal degradation induces a mixed Th1/Th2-type immune response

Targeting of a DNA vaccine encoded protein for degradation via the proteasome is attempted since it may enhance the immunogenicity of the vaccine. We have fused HIV-1 reverse transcriptase (RT) to mouse ornithine decarboxylase (ODC), a protein rapidly degraded by proteasome in an ubiquitine-independent fashion, to enhance the introduction of RT into the MHC class I pathway. We also designed a fusion of RT with two short signals from the C-terminus of ODC (ODCsig) representing a minimal proteasome-targeting moiety of ODC (PEST signal). Fusion to ODC or ODC signal domain led to a marked enhancement of RT degradation. Plasmids encoding RT-ODC and RT-ODCsig chimera were used to immunize BALB/c mice. The administration of the plasmids was not associated with autoimmune disease. Moreover, mice receiving RT-ODCsig gene mounted a mixed Th1/Th2 response characterized by the in vitro secretion of IFN-gamma, IL-2, TNF-alpha, IL-4, and IL-10 upon stimulation of splenocytes with RT protein or RT derived peptides. Serum titers of 10(2) to 10(3) were observed in more than 50% of animals in that group, whereas fewer animals mounted an anti-RT response in the RT-ODC gene immunized group. Chimeras of the type described here can, therefore, be used in vaccinations aiming to induce HIV-1 RT-specific immune response.

Mitigation of the plasma-implosion inhomogeneity in starlike wire-array Z pinches

Implosions in starlike triple and quadruple wire arrays were investigated in a 1 MA Zebra generator. Implosion in these loads is directed along the rays of the star and cascades from wire to wire to the center. Shadowgraphy shows improved homogeneity of imploding plasma and mitigation of instabilities. Despite the low azimuthal symmetry, starlike wire arrays produce a stable x-ray pulse with the highest peak power of >0.4 TW and the shortest duration of 8-12 ns among different types of tested loads. This can be linked to stabilization of instabilities due to the multiple nesting.

Excimer laser pumped by an intense, high-energy heavy-ion beam

High-energy heavy ions are an ideal tool to generate homogeneously excited, extended volumes of nonthermal plasmas. Here, the high-energy loss (dE/dx) and absolute power deposition of heavy ions interacting with matter has been used to pump an ultraviolet laser. A pulsed 70 MeV/u 238U beam with up to 2.5 x 10(9) particles in approximately 100 ns beam bunches was stopped in a 1.2 m long laser cell filled with a 1.6 bar Ar-Kr-F2 mixture (typically 50%:49.9%:0.1%). Laser effect on the 248 nm KrF* excimer transition is clearly demonstrated.

Energy-transfer processes in neon-hydrogen mixtures excited by electron beams

Energy- and charge-transfer processes in neon-hydrogen mixtures (500-1400 hPa neon and 0.001-3 hPa hydrogen partial pressures) excited by a pulsed low-energy (approximately 10 keV) electron beam were investigated using time-resolved spectroscopy. Time spectra of the hydrogen Lyman-alpha line, neon excimer emission (second continuum), and neon atomic lines (3p-3s transitions) were recorded. The time-integrated intensity of the Lyman-alpha emission was measured for the same range of gas mixtures. It is shown that direct energy transfer from Ne*2 excimers and neon atoms in the four lowest excited states as well as recombination of H3+ ions are the main channels populating atomic hydrogen in the n=2 state. A rate constant of (4.2+/-1.4)x10(-11) cm3 s(-1) was obtained for the charge transfer from Ne2+ ions to molecular hydrogen. A lower limit for the depopulation rate constant of Ne*2 excimers by molecular hydrogen (combination of energy transfer and ionization) was found to be 1.0 x 10(-10) cm3 s(-1).

Single-Photon Ionization Quadrupole Mass Spectrometry with an Electron Beam Pumped Excimer Light Source

The application of soft ionization methods for mass spectrometry (MS), such as single-photon ionization (SPI) using vacuum ultraviolet (VUV) light, provides powerful analytical instrumentation for real-time on-line monitoring of organic substances in gaseous matrixes. A compact and mobile quadrupole mass spectrometer (QMS) system using a novel electron beam pumped rare gas VUV lamp for SPI has been developed for on-line analysis of organic trace compounds (ppb concentrations). The VUV radiation of the light source is employed for SPI in the ion source of the QMS. The concept of the interfacing of the VUV light source with the QMS is described and the SPI-QMS is characterized. On-line detection limits down to 50 ppb for benzene, toluene, and m-xylene were achieved. The instrument is well suited for continuous measurements of aromatic and aliphatic trace compounds and can therefore be used for on-line monitoring of trace compounds in dynamically fluctuating process gases. First measurements of gas standards, petrochemical samples, and on-line monitoring of automotive exhaust are presented.

Hippocampal network patterns of activity in the mouse

Genetic engineering of the mouse brain allows investigators to address novel hypotheses in vivo. Because of the paucity of information on the network patterns of the mouse hippocampus, we investigated the electrical patterns in the behaving animal using multisite silicon probes and wire tetrodes. Theta (6-9 Hz) and gamma (40-100 Hz) oscillations were present during exploration and rapid eye movement sleep. Gamma power and theta power were comodulated and gamma power varied as a function of the theta cycle. Pyramidal cells and putative interneurons were phase-locked to theta oscillations. During immobility, consummatory behaviors and slow-wave sleep, sharp waves were present in cornu ammonis region CA1 of the hippocampus stratum radiatum associated with 140-200-Hz "ripples" in the pyramidal cell layer and population burst of CA1 neurons. In the hilus, large-amplitude "dentate spikes" occurred in association with increased discharge of hilar neurons. The amplitude of field patterns was larger in the mouse than in the rat, likely reflecting the higher neuron density in a smaller brain. We suggest that the main hippocampal network patterns are mediated by similar pathways and mechanisms in mouse and rat.

Raman amplification of ultrashort laser pulses in microcapillary plasmas

Experimental evidences of Raman amplification of ultrashort pulses in microcapillary plasmas are presented. The amplification of 100-500 fs pulses was investigated in microcapillaries with different lengths. The experimental data, together with simulation results, indicate that the resonance condition for Raman amplification in high-density plasma, n(e) approximately 1-3x10(20) cm(-3), existed only in a very short plasma column. Such an assumption makes it possible to reconcile the experimental results and theoretical predictions. Investigations in very short microcapillaries (0.2-0.5 mm) with a broadband seed pulse further support this hypothesis and the amplification factor is in agreement with the linear growth rate.

Some forms of cAMP-mediated long-lasting potentiation are associated with release of BDNF and nuclear translocation of phospho-MAP kinase

Long-lasting forms of synaptic plasticity like the late phase of LTP (L-LTP) typically require an elevation of cAMP, the recruitment of the cAMP-dependent protein kinase (PKA), and ultimately the activation of transcription and translation; some forms also require brain-derived neurotrophic factor (BDNF). Both cAMP and BDNF can activate mitogen-activated protein kinase (MAPK/ERK), which also plays a role in LTP. However, little is known about the mechanisms whereby cAMP, BDNF, and MAPK interact. We find that increases in cAMP can rapidly activate the BDNF receptor TrkB and induce BDNF-dependent long-lasting potentiation at the Schaffer collateral-CA1 synapse in hippocampus. Surprisingly, in these BDNF-dependent forms of potentiation, which are also MAPK dependent, TrkB activation is not critical for the activation of MAPK but instead appears to modulate the subcellular distribution and nuclear translocation of the activated MAPK.

Inhibition of HIV-1 virion production by a transdominant mutant of integrase interactor 1

Integase interactor 1 (INI1), also known as hSNF5, is a protein that interacts with HIV-1 integrase. We report here that a cytoplasmically localized fragment of INI1 (S6; aa183-294) containing the minimal integrase-interaction domain potently inhibits HIV-1 particle production and replication. Mutations in S6 or integrase that disrupt integrase-INI1 interaction abrogated the inhibitory effect. An integrase-deficient HIV-1 transcomplemented with integrase fused to Vpr was not affected by S6. INI1 was specifically incorporated into virions and was required for efficient HIV-1 particle production. These results indicate that INI1 is required for late events in the viral life cycle, and that ectopic expression of S6 inhibits HIV-1 replication in a transdominant manner via its specific interaction with integrase within the context of Gag-Pol, providing a novel strategy to control HIV-1 replication.

Structure-function analysis of integrase interactor 1/hSNF5L1 reveals differential properties of two repeat motifs present in the highly conserved region

Retroviral integrase (IN) catalyzes the integration of retroviral cDNA into host chromosome. Ini1 (integrase interactor 1) is a host protein that specifically binds and stimulates in vitro joining activity of HIV-1 IN. Ini1 has homology to yeast transcription factor SNF5 and is a component of the analogous mammalian SWI/SNF complex that can remodel chromatin. Little is known about the function of Ini1 in mammalian cells. To gain insight into the functional domains of Ini1, and to understand the details of protein-protein interactions of IN and Ini1, a structure-function analysis of Ini1 was initiated. By means of the yeast two-hybrid system, the minimal IN binding domain of Ini1 was characterized. One of the two repeat motifs present in the highly conserved regions of Ini1 was found necessary and sufficient to bind to IN in yeast as well as in vitro. Because IN binds to only one of the two repeat motifs in this conserved region of Ini1, it appears that the IN-Ini1 interaction is very specific and functionally significant. Characterization of DNA-binding properties of Ini1 revealed that Ini1 can bind to plasmid DNA, binding more readily to supercoiled DNA than to the relaxed circular DNA. The minimal domain for DNA binding was localized to a region upstream of repeat 1. The DNA binding activity of Ini1 is not required for its ability to interact with IN. The finding that the two repeat motifs of Ini1 display differential binding to HIV-1 IN and that this discrete component of mammalian SWI/SNF complex binds to DNA will help understand the role of Ini1 in HIV-1 integration and in cellular process.

Differential regulation of the pocket domains of the retinoblastoma family proteins by the HPV16 E7 oncoprotein

The human papillomavirus E7 oncoprotein binds to the retinoblastoma (Rb) tumor suppressor protein, and the binding to Rb correlates with the oncogenic potential of E7. Recent studies from several laboratories indicated that the half-life of the Rb protein is reduced in cells that are stably transformed with E7, suggesting that E7 could induce the proteolytic degradation of Rb. To investigate whether the Rb degradation is a primary effect of E7 or a result of altered cell phenotype, we sought to develop assays that can distinguish between the two possibilities. Using recombinant adenovirus expressing the human papillomavirus type 16 E7 protein, we show that the expression of E7 leads to an increased rate of decay of the Rb protein. Moreover, Rb degradation immediately follows the expression of E7 suggesting that it is an early and primary effect. Consistent with a previous study, we observed that the E7-induced degradation of Rb can be blocked by the inhibitors of the 26S proteasome. We have also developed a transient transfection assay for the E7-induced degradation of Rb. Using this assay, we show that the pocket domain of Rb is necessary and sufficient for the E7-induced degradation. However, the proteolysis is relatively specific for Rb because the level of p107 or p130 was not significantly altered by the expression of E7. Thus, although E7 binds to all three members of the Rb family of proteins, the proteolysis is much more efficient in the case of Rb. In the transient transfection assays, adenovirus E1A and SV40 large T antigen failed to induce degradation of Rb, suggesting that the Rb degradation is a unique property of the E7 oncoprotein.

Accumulation of human papillomavirus type 16 E7 protein bypasses G1 arrest induced by serum deprivation and by the cell cycle inhibitor p21

The E7 oncoproteins encoded by the high-risk type of human papillomaviruses (HPVs) interact with the Rb family proteins Rb, p107, and p130. The Rb family proteins associate with the factors of the E2F family to form transcription repressor complexes, which control expression of several genes essential for S-phase entry and DNA replication. The E7 oncoproteins, by interacting with the Rb family proteins, dissociate the repressor complexes involving the factors of the E2F and Rb families, leading to a release of the E2F factors in their activator forms. In this study, we have addressed the mechanism by which the HPV type 16 (HPV16) E7 stimulates the cell cycle. Using a cell line that inducibly expresses the HPV16 E7 protein, we show that an accumulation of E7 induces quiescent cells to enter S phase and that this function of E7 depends on retention of the motif involved in binding to the Rb family proteins. To study the effects of E7 on normal human cells, we generated a recombinant adenovirus that expresses the HPV16 E7 protein. Infection of normal human fibroblasts, which were arrested in G1 phase by serum deprivation, with the E7-expressing virus induced the cells to enter S phase. The E7-induced S phase entry was accompanied by an increase in the activator form of E2F, but no increase in the cyclin-dependent kinase (cdk) activity was detected. Infection of serum-stimulated fibroblasts with a recombinant adenovirus expressing the cdk inhibitor p21 inhibited progression into S phase. Coinfection with the E7-expressing virus abrogated the p21 inhibition of progression into S phase without increasing the cdk activity. These results are consistent with the notion that E7 stimulates entry into S phase through targets downstream of the cdks such as the proteins of the E2F and Rb families.