Localisation of the human hSuv3p helicase in the mitochondrial matrix and its preferential unwinding of dsDNA

We characterised the human hSuv3p protein belonging to the family of NTPases/helicases. In yeast mitochondria the hSUV3 orthologue is a component of the degradosome complex and participates in mtRNA turnover and processing, while in Caenorhabditis elegans the hSUV3 orthologue is necessary for viability of early embryos. Using immunofluorescence analysis, an in vitro mitochondrial uptake assay and sub‐fractionation of human mitochondria we show hSuv3p to be a soluble protein localised in the mitochondrial matrix. We expressed and purified recombinant hSuv3p protein from a bacterial expression system. The purified enzyme was capable of hydrolysing ATP with a Km of 41.9 µM and the activity was only modestly stimulated by polynucleotides. hSuv3p unwound partly hybridised dsRNA and dsDNA structures with a very strong preference for the latter. The presented analysis of the hSuv3p NTPase/helicase suggests that new functions of the protein have been acquired in the course of evolution

The non-ballistic superluminal motion in the plane of the sky-II

The model of non-ballistic jet motion proposed in 2008 provides a simple explanation to the inward jet motion and bent jet. Recently, evidences of such a non-radial motion increase rapidly, and more complicated morphologies appear. On the other hand, the ballistic plus precession model likely holds in majority samples of jet motion. This paper discusses the relationship between the ballistic and non-ballistic model of jet motion, which suggests that the interaction of ejectors with ambient matter can produce knots at different stages of evolution and hence different separations to the core. And as a jet precesses, knots produced between the core and the deceleration radius result in spiral pattern expected by the model of ballistic plus precession; and knots generated at the deceleration radius display non-radial motion such as bent jet or oscillation of ridge-line. This paper develops the first non-ballistic model in four aspects. Firstly, it provides a numerical simulation to the production of multi-knot for a precessing jet. Secondly, it fits the precession behavior of multi-knot and interprets the oscillation of ridge lines like S5 1803+784. Thirdly, it gives an unified interpretation to the bent jet applicable to both multi-knot and single knot. And fourthly, the problem of very large numbers of observed outward motions as opposed to the inward ones is addressed in a new scope.Comment: 9 pages, 6 figures, accepted by MNRA

A One-sided, Highly Relativistic Jet from Cygnus X-3

Very Long Baseline Array images of the X-ray binary, Cygnus X-3, were obtained 2, 4 and 7 days after the peak of a 10 Jy flare on 4 February 1997. The first two images show a curved one-sided jet, the third a scatter-broadened disc, presumably at the position of the core. The jet curvature changes from the first to the second epoch, which strongly suggests a precessing jet. The ratio of the flux density in the approaching to that in the (undetected) receding jet is > 330; if this asymmetry is due to Doppler boosting, the implied jet speed is > 0.81c. Precessing jet model fits, together with the assumptions that the jet is intrinsically symmetric and was ejected during or after the major flare, yield the following constraints: the jet inclination to the line of sight must be < 14 degrees; the cone opening angle must be < 12 degrees; and the precession period must be > 60 days.Comment: 12 pages 7 figures, accepted by Ap

Orbital dynamics of Cygnus X-3

Orbital-phased-resolved infrared spectra of Cygnus X-3 in outburst and quiescence, including tomographic analysis, are presented. We confirm the phasing of broad HeII and NV lines in quiescence, such that maximum blue shift corresponds to the X-ray minimum at phase = 0.00 +/- 0.04. In outburst, double-peaked HeI structures show a similar phasing with two significant differences: (a) although varying in relative strength, there is continuous line emission in blue and red peaks around the orbit, and (b) an absorption component, ~1/4 of an orbit out of phase with the emission features, is discerned. Doppler tomograms of the double-peaked profiles are consistent with a disk-wind geometry, rotating at velocities of 1000 km/s. Regrettably, the tomography algorithm will produce a similar ring structure from alternative line sources if contaminated by overlying P Cygni profiles. This is certainly the case in the strong 2.0587 micron HeI line, leading to an ambiguous solution for the nature of double-peaked emission. The absorption feature, detected 1/4 of an orbit out of phase with the emission features, is consistent with an origin in the He star wind and yields for the first time a plausible radial velocity curve for the system. We directly derive the mass function of the system, 0.027 M_sun. If we assume a neutron star accretor and adopt a high orbital inclination, i > 60 degrees, we obtain a mass range for the He star of 5 M_sun < M_WR < 11 M_sun. Alternatively if the compact object is a black hole, we estimate M_BH < 10 M_sun. We discuss the implications of these masses for the nature and size of the binary system.Comment: Accepted for publication in ApJ main journa

Sco X-1: The Evolution and Nature of the Twin Compact Radio Lobes

The radio components associated with the LMXB Sco X-1 have been monitored with extensive VLBI imaging at 1.7 and 5.0 GHz over four years, including a 56-hour continuous VLBI observation in 1999 June. We often detected one strong and one weak compact radio component, moving in opposite directions from the radio core. We suggest that the moving components are radio lobes generated by the disruption of energy flow in a twin-beam from the binary system. The average lifetime of a lobe-pair, the space motion of the lobes and the measured energy flow in the beam are discussed in arXiv:astro-ph/0104325. The lobe has a flux density that is variable over a time-scale of one hour, a measured minimum size of 1 mas (2.8 au), and is extended perpendicular to its motion. This short electron radiative lifetime may be caused by synchrotron losses if the lobe magnetic field is 300 G, or by adiabatic expansion of the electrons as soon as they are produced at the working surface. The lobes also show periods of slow expansion and a steepening radio spectrum, perhaps related to the characteristics of the beam energy flow. The radio morphology for Sco X-1 is more simple than for most other Galactic jet sources. The lobes of Sco X-1 are similar to hot-spots found in many extragalactic double sources. Scaling the phenomena observed in Sco X-1 to extragalactic sources implies hot-spot variability time-scales of 10^4 yr and hot-spot lifetimes of 10^5 yr. The recurrent formation of lobes in Sco X-1 probably does not occur for extragalactic radio sources.Comment: 22 pages of text + 16 figures. ApJ, in pres

The Hardness-Intensity Diagram of Cygnus X-3: Revisiting the Radio/X-Ray States

Cygnus X-3 is one of the brightest X-ray and radio sources in the Galaxy, and is well known for its erratic behaviour in X-rays as well as in the radio, occasionally producing major radio flares associated with relativistic ejections. However, even after many years of observations in various wavelength bands Cyg X-3 still eludes clear physical understanding. Studying different emission bands simultaneously in microquasars has proved to be a fruitful approach towards understanding these systems, especially by shedding light on the accretion disc/jet connection. We continue this legacy by constructing a hardness-intensity diagram (HID) from archival Rossi X-ray Timing Explorer data and linking simultaneous radio observations to it. We find that surprisingly Cyg X-3 sketches a similar shape in the HID to that seen in other transient black hole X-ray binaries during outburst but with distinct differences. Together with the results of this analysis and previous studies of Cyg X-3 we conclude that the X-ray states can be assigned to six distinct states. This categorization relies heavily on the simultaneous radio observations and we identify one new X-ray state, the hypersoft state, similar to the ultrasoft state, which is associated to the quenched radio state during which there is no or very faint radio emission. Recent observations of GeV flux observed from Cyg X-3 (Tavani et al. 2009; Fermi LAT Collaboration et al. 2009) during a soft X-ray and/or radio quenched state at the onset of a major radio flare hint that a very energetic process is at work during this time, which is also when the hypersoft X-ray state is observed. In addition, Cyg X-3 shows flaring with a wide range of hardness.Comment: 17 pages, 9 figures, accepted for publication in MNRA

Dissociating the effects of alternative early-life feeding schedules on the development of adult depression-like phenotypes

Neville, V., Andrews, C., Nettle, D. and M. Bateson (2017). Dissociating the effects of alternative early-life feeding schedules on the development of adult depression-like phenotypes. Scientific Reports 7: 14832

Megaesophagus and Possible Mechanisms of Sudden Death

Achalasia is a neurodegenerative condition characterized by esophageal dysmotility and megaesophagus. Two cases are reported that demonstrate unexpected deaths associated with previously unsuspected achalasia. Case 1: A 66-year-old woman was found dead at her home. At autopsy significant stenosing coronary artery atherosclerosis was found with cardiac failure. In addition, a striking finding was narrowing of the distal esophagus with marked proximal dilatation. The esophagus was completely filled with a large amount of soft masticated food and was bulging anteriorly, compressing the left atrium. Death was attributed to ischemic heart disease complicated by previously unsuspected achalasia. Case 2: An 84-year-old man collapsed and suffered a respiratory arrest while eating. Internal examination revealed narrowing of the cardioesophageal junction with marked proximal dilatation of the esophagus that contained approximately 50 mL of soft semi-fluid masticated yellow food paste. Fragments of yellow masticated food remnants were present in upper and lower airways but not within the stomach. There was a history of dementia with symmetrical cerebral ventricular dilatation found at autopsy. Death was attributed to food asphyxia complicating previously unsuspected achalasia with dementia. Megaesophagus may, therefore, be a significant finding at autopsy that may either be a primary cause of unexpected death or else may exacerbate or compound the effects of pre-existing underlying disease.Sarah Schalinski, Saskia S. Guddat, Michael Tsokos, and Roger W. Byar

Vertebral column kyphoscoliosis and unexpected death

The original publication can be found at www.springerlink.comA case of spontaneous gastric perforation is reported in a 75-year-old woman due to massive hemorrhaging from a benign gastric ulcer. Blood was prevented from leaving the stomach due to posterior displacement and rotation of the stomach associated with marked underlying vertebral column kyphoscoliosis. Significant deformity of the spine had caused malpositioning of the stomach as a result of the abnormal shape of the peritoneal and chest cavities. This in turn had led to mechanical obstruction and prevented egress of blood arising from a bleeding arteriole in the base of a chronic gastric ulcer. Rapid distension had resulted from the inability to spontaneously decompress the stomach, which in turn had led to rupture.Saskia S. Guddat, Michael Tsokos, Sarah Schalinski and Roger W. Byar