No increase in radiation-induced chromosome aberration complexity detected by m-FISH after culture in the presence of 5’-bromodeoxyuridine

The thymidine analogue, 5’-bromodeoxyuridine (BrdU), is a known mutagen that is routinely introduced into culture media for subsequent Harlequin stain analysis and determination of cell cycle status. Previously, we examined the induction of chromosome aberrations in human peripheral blood lymphocytes (PBL) known to be in their 1st cell division following exposure to a low dose (0.5 Gy, average one -particle per cell) of high-LET α-particles. We found complex chromosome aberrations to be characteristic of exposure to high-LET radiation and suggested the features of complex exchange to reflect qualitatively the spatial deposition of this densely ionising radiation. To exclude the possibility that BrdU addition post-irradiation influenced the complexity of chromosomal damage observed by m-FISH, the effect of increasing BrdU concentration on aberration complexity was investigated. Comparisons between BrdU concentration (0, 10, and 40 M) and between sham- and α-particle irradiated PBL, were made both independently and in combination to enable discrimination between BrdU and high-LET radiation effects. Aberration type, size, complexity and completeness were assessed by m-FISH, and the relative progression through cell division was evaluated. We found no evidence of any qualitative difference in the complexity of damage as visualized by m-FISH but did observe an increase in the frequency of complex exchanges with increasing BrdU concentration indicative of altered cell cycle kinetics. The parameters measured here are consistent with findings from previous in vitro and in vivo work, indicating that each complex aberration visualised by m-FISH is characteristic of the structure of the high-LET α-particle track and the geometry of cell irradiated

Northern Bobwhite Response to Control of Red Imported Fire Ants in the Gulf Coast Prairie of Texas

The population decline of northern bobwhite (Colinus virginianus; hereafter, bobwhite) on the Texas Gulf Coast Prairie, USA is largely attributed to habitat loss. However, red imported fire ants (Solenopsis invicta) occur throughout the region and are considered a possible contributing factor to the bobwhite decline. The objectives of our study were to determine the influence of red imported fire ants on bobwhites by comparing bobwhite nest success, survival, and density between sites treated with fire ant bait (treatment) and reference (control) sites. Our study was conducted on 3 private ranches in Goliad and Refugio counties, Texas. Each ranch contained 2 paired experimental units that consisted of a treatment and control site (500 ha each). The treatment sites received an aerial application of fire ant bait (Extinguish® Plus) during April 2018, whereas the control sites were not treated. We estimated mound density by counting fire ant mounds using distance sampling. We used radio-telemetry to monitor bobwhite nest success and survival, and we estimated bobwhite densities using distance sampling via helicopter surveys. Fire ant mound density decreased through time on both treatment and control sites. However, fire ant mound density was lower on treatment sites than control sites, indicating the insecticide was effective at decreasing fire ant mound density. Bobwhite survival, nest success, and density did not statistically differ between control and treated sites either pre-treatment (2017) or post-treatment (2018), but survival and nest success metrics were numerically higher in treated units. Bobwhite survival remained relatively stable in the treatment units 4 weeks after application but decreased in the control units. Following treatment, apparent nest success in the treated units increased by 37.4% while nest success in the control units decreased by 35.2%. Bobwhite populations were low in this ecoregion, which influenced our ability to trap and monitor many bobwhites or monitor many nests. In addition, it may be possible that repeated, annual treatments for fire ants are necessary for a benefit to accrue and be observed in bobwhites. Our results indicate that there may be potential benefits to bobwhites from fire ant reduction that deserve further research attention

Linked Autonomous Interplanetary Satellite Orbit Navigation

A navigation technology known as LiAISON (Linked Autonomous Interplanetary Satellite Orbit Navigation) has been known to produce very impressive navigation results for scenarios involving two or more cooperative satellites near the Moon, such that at least one satellite must be in an orbit significantly perturbed by the Earth, such as a lunar halo orbit. The two (or more) satellites track each other using satellite-to-satellite range and/or range-rate measurements. These relative measurements yield absolute orbit navigation when one of the satellites is in a lunar halo orbit, or the like. The geometry between a lunar halo orbiter and a GEO satellite continuously changes, which dramatically improves the information content of a satellite-to-satellite tracking signal. The geometrical variations include significant out-of-plane shifts, as well as inplane shifts. Further, the GEO satellite is almost continuously in view of a lunar halo orbiter. High-fidelity simulations demonstrate that LiAISON technology improves the navigation of GEO orbiters by an order of magnitude, relative to standard ground tracking. If a GEO satellite is navigated using LiAISON- only tracking measurements, its position is typically known to better than 10 meters. If LiAISON measurements are combined with simple radiometric ground observations, then the satellite s position is typically known to better than 3 meters, which is substantially better than the current state of GEO navigation. There are two features of LiAISON that are novel and advantageous compared with conventional satellite navigation. First, ordinary satellite-to-satellite tracking data only provides relative navigation of each satellite. The novelty is the placement of one navigation satellite in an orbit that is significantly perturbed by both the Earth and the Moon. A navigation satellite can track other satellites elsewhere in the Earth-Moon system and acquire knowledge about both satellites absolute positions and velocities, as well as relative positions and velocities in space. The second novelty is that ordinarily one requires many satellites in order to achieve full navigation of any given customer s position and velocity over time. With LiAISON navigation, only a single navigation satellite is needed, provided that the satellite is significantly affected by the gravity of the Earth and the Moon. That single satellite can track another satellite elsewhere in the Earth- Moon system and obtain absolute knowledge of both satellites states

On the multiple supernova population of Arp 299: constraints on progenitor properties and host galaxy star formation characteristics

Throughout the last 20 years 7 supernovae (SNe) have been discovered within Arp 299. One of these is unclassified, leaving 6 core-collapse events; 2 type II, 2 type Ib, a type IIb and one object of indistinct type; Ib/IIb. We analyse the relative numbers of these types, together with their positions with respect to host galaxy properties, to investigate implications for both progenitor characteristics and star formation (SF) properties. Our findings are: 1) the ratio of 'stripped envelope' (SE) events to other type II is higher than that found in the local Universe. 2) All SE SNe are more centrally concentrated within the system than the other type II. 3) All SN environments have similar metallicities and there are no significant metallicity gradients across the system. 4) The SE SNe all fall on bright SF regions while the other type II are found to occur away from bright HII regions. We draw two different -but non-mutually exclusive- interpretations on the system and its supernovae: 1) The distribution of SNe, and the relatively high fraction of types Ib and IIb events over other type II can be explained by the young age of the most recent SF in the system, where insufficient time has expired for the observed to match the 'true' relative SN rates. This explanation provides additional independent evidence that both types Ib and IIb SNe arise from progenitors of shorter stellar lifetime and hence higher mass than other type II. 2) Given the assumption that types Ib and IIb trace higher mass progenitor stars, the relatively high frequency of types Ib and IIb to other type II, and also the centralisation of the former over the latter with respect to host galaxy light implies that in the centrally peaked and enhanced SF within this system, the initial mass function is biased towards the production of high mass stars.Comment: 13 pages, 4 figures. Accepted for publication in MNRAS. The abstract has been edited to fit within arXiv.org submission requirement

Peculiar Type II Supernovae from Blue Supergiants

The vast majority of Type II supernovae (SNe) are produced by red supergiants (RSGs), but SN 1987A revealed that blue supergiants (BSGs) can produce members of this class as well, albeit with some peculiar properties. This best studied event revolutionized our understanding of SNe, and linking it to the bulk of Type II events is essential. We present here optical photometry and spectroscopy gathered for SN 2000cb, which is clearly not a standard Type II SN and yet is not a SN 1987A analog. The light curve of SN 2000cb is reminiscent of that of SN 1987A in shape, with a slow rise to a late optical peak, but on substantially different time scales. Spectroscopically, SN 2000cb resembles a normal SN II but with ejecta velocities that far exceed those measured for SN 1987A or normal SNe II, above 18000 km/s for H-alpha at early times. The red colours, high velocities, late photometric peak, and our modeling of this object all point toward a scenario involving the high-energy explosion of a small-radius star, most likely a BSG, producing 0.1 solar masses of Ni-56. Adding a similar object to the sample, SN 2005ci, we derive a rate of about 2% of the core-collapse rate for this loosely defined class of BSG explosions.Comment: Accepted to MNRAS on March 14, 201

B Lineage–specific Regulation of V(D)J Recombinase Activity Is Established in Common Lymphoid Progenitors

Expression of V(D)J recombinase activity in developing lymphocytes is absolutely required for initiation of V(D)J recombination at antigen receptor loci. However, little is known about when during hematopoietic development the V(D)J recombinase is first active, nor is it known what elements activate the recombinase in multipotent hematopoietic progenitors. Using mice that express a fluorescent transgenic V(D)J recombination reporter, we show that the V(D)J recombinase is active as early as common lymphoid progenitors (CLPs) but not in the upstream progenitors that retain myeloid lineage potential. Evidence of this recombinase activity is detectable in all four progeny lineages (B, T, and NK, and DC), and rag2 levels are the highest in progenitor subsets immediately downstream of the CLP. By single cell PCR, we demonstrate that V(D)J rearrangements are detectable at IgH loci in ∼5% of splenic natural killer cells. Finally, we show that recombinase activity in CLPs is largely controlled by the Erag enhancer. As activity of the Erag enhancer is restricted to the B cell lineage, this provides the first molecular evidence for establishment of a lineage-specific transcription program in multipotent progenitors

Gold nanoparticles as catalysts for low-temperature WGS reaction

OBJECTIVES: This study aimed to compare the phenotype of Rett syndrome cases with C-terminal deletions to that of cases with different MECP2 mutations and to examine the phenotypic variation within C-terminal deletions. METHODS: Cases were selected from InterRett, an international database and from the population-based Australian Rett Syndrome Database. Cases (n=832) were included if they had a pathogenic MECP2 mutation in which the nature of the amino acid change was known. Three severity scale systems were used, and individual aspects of the phenotype were also compared. RESULTS: Lower severity was associated with C-terminal deletions (n=79) compared to all other MECP2 mutations (e.g. Pineda scale C-terminals mean 15.0 (95% CI 14.0–16.0) vs 16.2 (15.9–16.5). Cases with C-terminal deletions were more likely to have a normal head circumference (odds ratio 3.22, 95% CI 1.53 – 6.79) and weight (odds ratio 2.97, 95% CI 1.25–5.76). Onset of stereotypies tended to be later (median age 2.5 years vs 2 years, p<0.001 from survival analysis), and age of learning to walk tended to be earlier (median age 1.6 years vs 2 years, p=0.002 from survival analysis). Those with C-terminal deletions occurring later in the region had lower average severity scores than those occurring earlier in the region. CONCLUSION: In terms of overall severity C-terminal deletion cases would appear to be in the middle of the range. In terms of individual aspects of phenotype growth and ability to ambulate appear to be particular strengths. By pooling data internationally this study has achieved the case numbers to provide a phenotypic profile of C-terminal deletions in Rett syndrome

Depression and sickness behavior are Janus-faced responses to shared inflammatory pathways

It is of considerable translational importance whether depression is a form or a consequence of sickness behavior. Sickness behavior is a behavioral complex induced by infections and immune trauma and mediated by pro-inflammatory cytokines. It is an adaptive response that enhances recovery by conserving energy to combat acute inflammation. There are considerable phenomenological similarities between sickness behavior and depression, for example, behavioral inhibition, anorexia and weight loss, and melancholic (anhedonia), physio-somatic (fatigue, hyperalgesia, malaise), anxiety and neurocognitive symptoms. In clinical depression, however, a transition occurs to sensitization of immuno-inflammatory pathways, progressive damage by oxidative and nitrosative stress to lipids, proteins, and DNA, and autoimmune responses directed against self-epitopes. The latter mechanisms are the substrate of a neuroprogressive process, whereby multiple depressive episodes cause neural tissue damage and consequent functional and cognitive sequelae. Thus, shared immuno-inflammatory pathways underpin the physiology of sickness behavior and the pathophysiology of clinical depression explaining their partially overlapping phenomenology. Inflammation may provoke a Janus-faced response with a good, acute side, generating protective inflammation through sickness behavior and a bad, chronic side, for example, clinical depression, a lifelong disorder with positive feedback loops between (neuro)inflammation and (neuro)degenerative processes following less well defined triggers