Detecting the orientation of magnetic fields in galaxy clusters

Clusters of galaxies, filled with hot magnetized plasma, are the largest bound objects in existence and an important touchstone in understanding the formation of structures in our Universe. In such clusters, thermal conduction follows field lines, so magnetic fields strongly shape the cluster's thermal history; that some have not since cooled and collapsed is a mystery. In a seemingly unrelated puzzle, recent observations of Virgo cluster spiral galaxies imply ridges of strong, coherent magnetic fields offset from their centre. Here we demonstrate, using three-dimensional magnetohydrodynamical simulations, that such ridges are easily explained by galaxies sweeping up field lines as they orbit inside the cluster. This magnetic drape is then lit up with cosmic rays from the galaxies' stars, generating coherent polarized emission at the galaxies' leading edges. This immediately presents a technique for probing local orientations and characteristic length scales of cluster magnetic fields. The first application of this technique, mapping the field of the Virgo cluster, gives a startling result: outside a central region, the magnetic field is preferentially oriented radially as predicted by the magnetothermal instability. Our results strongly suggest a mechanism for maintaining some clusters in a 'non-cooling-core' state.Comment: 48 pages, 21 figures, revised version to match published article in Nature Physics, high-resolution version available at http://www.cita.utoronto.ca/~pfrommer/Publications/pfrommer-dursi.pd

A model for transition of 5 '-nuclease domain of DNA polymerase I from inert to active modes

Bacteria contain DNA polymerase I (PolI), a single polypeptide chain consisting of similar to 930 residues, possessing DNA-dependent DNA polymerase, 3'-5' proofreading and 5'-3' exonuclease (also known as flap endonuclease) activities. PolI is particularly important in the processing of Okazaki fragments generated during lagging strand replication and must ultimately produce a double-stranded substrate with a nick suitable for DNA ligase to seal. PolI's activities must be highly coordinated both temporally and spatially otherwise uncontrolled 5'-nuclease activity could attack a nick and produce extended gaps leading to potentially lethal double-strand breaks. To investigate the mechanism of how PolI efficiently produces these nicks, we present theoretical studies on the dynamics of two possible scenarios or models. In one the flap DNA substrate can transit from the polymerase active site to the 5'-nuclease active site, with the relative position of the two active sites being kept fixed; while the other is that the 5'-nuclease domain can transit from the inactive mode, with the 5'-nuclease active site distant from the cleavage site on the DNA substrate, to the active mode, where the active site and substrate cleavage site are juxtaposed. The theoretical results based on the former scenario are inconsistent with the available experimental data that indicated that the majority of 5'-nucleolytic processing events are carried out by the same PolI molecule that has just extended the upstream primer terminus. By contrast, the theoretical results on the latter model, which is constructed based on available structural studies, are consistent with the experimental data. We thus conclude that the latter model rather than the former one is reasonable to describe the cooperation of the PolI's polymerase and 5'-3' exonuclease activities. Moreover, predicted results for the latter model are presented

Factors Associated with herb and dietary supplement use by young adults in the United States

<p>Abstract</p> <p>Background</p> <p>Little is known about the association between use of herbs and dietary supplements (HDS) and lifestyle/behavior factors in young adults in the US.</p> <p>Methods</p> <p>Analyzing the 2002 National Health Interview Survey (NHIS), we examined the patterns of HDS (excluding vitamins/minerals) use among young adults in the United States using descriptive statistics and logistic regression.</p> <p>Results</p> <p>In our sample of 18 to 30 year olds (n = 6666), 26% were current smokers, 24% were moderate/heavy drinkers, 43% had high physical activity, and 54% and 76% use prescription and over the counter (OTC) medications respectively. Non-vitamin, non-mineral HDS was used by 17% of the overall sample in the last 12 months. In the multivariable analysis, the lifestyle and behavioral factors associated with HDS use include: current smoking (odds ratio 1.41 95% CI [1.16–1.72]); being a former smoker (1.50 [1.15–1.95]); moderate/heavy alcohol use (2.02 [1.53–2.65]); high physical activity levels (2.45 [1.98–3.03]); and prescription medication use (1.51 [1.26–1.81]). Among HDS users, only 24% discussed their use with a health care professional.</p> <p>Conclusion</p> <p>Nearly one in five young adults report using non-vitamin/non-mineral HDS.</p

Features of mammalian microRNA promoters emerge from polymerase II chromatin immunoprecipitation data

Background: MicroRNAs (miRNAs) are short, non-coding RNA regulators of protein coding genes. miRNAs play a very important role in diverse biological processes and various diseases. Many algorithms are able to predict miRNA genes and their targets, but their transcription regulation is still under investigation. It is generally believed that intragenic miRNAs (located in introns or exons of protein coding genes) are co-transcribed with their host genes and most intergenic miRNAs transcribed from their own RNA polymerase II (Pol II) promoter. However, the length of the primary transcripts and promoter organization is currently unknown. Methodology: We performed Pol II chromatin immunoprecipitation (ChIP)-chip using a custom array surrounding regions of known miRNA genes. To identify the true core transcription start sites of the miRNA genes we developed a new tool (CPPP). We showed that miRNA genes can be transcribed from promoters located several kilobases away and that their promoters share the same general features as those of protein coding genes. Finally, we found evidence that as many as 26% of the intragenic miRNAs may be transcribed from their own unique promoters. Conclusion: miRNA promoters have similar features to those of protein coding genes, but miRNA transcript organization is more complex. © 2009 Corcoran et al

A Potential Role for Bat Tail Membranes in Flight Control

Wind tunnel tests conducted on a model based on the long-eared bat Plecotus auritus indicated that the positioning of the tail membrane (uropatagium) can significantly influence flight control. Adjusting tail position by increasing the angle of the legs ventrally relative to the body has a two-fold effect; increasing leg-induced wing camber (i.e., locally increased camber of the inner wing surface) and increasing the angle of attack of the tail membrane. We also used our model to examine the effects of flying with and without a tail membrane. For the bat model with a tail membrane increasing leg angle increased the lift, drag and pitching moment (nose-down) produced. However, removing the tail membrane significantly reduced the change in pitching moment with increasing leg angle, but it had no significant effect on the level of lift produced. The drag on the model also significantly increased with the removal of the tail membrane. The tail membrane, therefore, is potentially important for controlling the level of pitching moment produced by bats and an aid to flight control, specifically improving agility and manoeuvrability. Although the tail of bats is different from that of birds, in that it is only divided from the wings by the legs, it nonetheless, may, in addition to its prey capturing function, fulfil a similar role in aiding flight control

A Potential Role for Bat Tail Membranes in Flight Control

Wind tunnel tests conducted on a model based on the long-eared bat Plecotus auritus indicated that the positioning of the tail membrane (uropatagium) can significantly influence flight control. Adjusting tail position by increasing the angle of the legs ventrally relative to the body has a two-fold effect; increasing leg-induced wing camber (i.e., locally increased camber of the inner wing surface) and increasing the angle of attack of the tail membrane. We also used our model to examine the effects of flying with and without a tail membrane. For the bat model with a tail membrane increasing leg angle increased the lift, drag and pitching moment (nose-down) produced. However, removing the tail membrane significantly reduced the change in pitching moment with increasing leg angle, but it had no significant effect on the level of lift produced. The drag on the model also significantly increased with the removal of the tail membrane. The tail membrane, therefore, is potentially important for controlling the level of pitching moment produced by bats and an aid to flight control, specifically improving agility and manoeuvrability. Although the tail of bats is different from that of birds, in that it is only divided from the wings by the legs, it nonetheless, may, in addition to its prey capturing function, fulfil a similar role in aiding flight control

Does pharmaceutical advertising affect journal publication about dietary supplements?

<p>Abstract</p> <p>Background</p> <p>Advertising affects consumer and prescriber behaviors. The relationship between pharmaceutical advertising and journals' publication of articles regarding dietary supplements (DS) is unknown.</p> <p>Methods</p> <p>We reviewed one year of the issues of 11 major medical journals for advertising and content about DS. Advertising was categorized as pharmaceutical versus other. Articles about DS were included if they discussed vitamins, minerals, herbs or similar products. Articles were classified as major (e.g., clinical trials, cohort studies, editorials and reviews) or other (e.g., case reports, letters, news, and others). Articles' conclusions regarding safety and effectiveness were coded as negative (unsafe or ineffective) or other (safe, effective, unstated, unclear or mixed).</p> <p>Results</p> <p>Journals' total pages per issue ranged from 56 to 217 while advertising pages ranged from 4 to 88; pharmaceutical advertisements (pharmads) accounted for 1.5% to 76% of ad pages. Journals with the most pharmads published significantly fewer major articles about DS per issue than journals with the fewest pharmads (P < 0.01). Journals with the most pharmads published no clinical trials or cohort studies about DS. The percentage of major articles concluding that DS were unsafe was 4% in journals with fewest and 67% among those with the most pharmads (P = 0.02). The percentage of articles concluding that DS were ineffective was 50% higher among journals with more than among those with fewer pharmads (P = 0.4).</p> <p>Conclusion</p> <p>These data are consistent with the hypothesis that increased pharmaceutical advertising is associated with publishing fewer articles about DS and publishing more articles with conclusions that DS are unsafe. Additional research is needed to test alternative hypotheses for these findings in a larger sample of more diverse journals.</p

Genotyping of single nucleotide polymorphisms related to attention-deficit hyperactivity disorder

Pharmacological treatment of several diseases, such as attention-deficit hyperactivity disorder (ADHD), presents marked variability in efficiency and its adverse effects. The genotyping of specific single nucleotide polymorphisms (SNPs) can support the prediction of responses to drugs and the genetic risk of presenting comorbidities associated with ADHD. This study presents two rapid and affordable microarray-based strategies to discriminate three clinically important SNPs in genes ADRA2A, SL6CA2, and OPRM1 (rs1800544, rs5569, and rs1799971, respectively). These approaches are allele-specific oligonucleotide hybridization (ASO) and a combination of allele-specific amplification (ASA) and solid-phase hybridization. Buccal swab and blood samples taken from ADHD patients and controls were analyzed by ASO, ASA, and a gold-reference method. The results indicated that ASA is superior in genotyping capability and analytical performance.This research has been funded through projects FEDER MINECO INNPACTO IPT-2011-1132-010000, CTQ/2013/45875R, and PrometeoII/2014/040 (GVA).Tortajada-Genaro, LA.; Mena-Mollá, S.; Niñoles Rodenes, R.; Puigmule, M.; Viladevall, L.; Maquieira Catala, Á. (2016). Genotyping of single nucleotide polymorphisms related to attention-deficit hyperactivity disorder. Analytical and Bioanalytical Chemistry. 408(9):2339-2345. https://doi.org/10.1007/s00216-016-9332-3S233923454089Cortese S. The neurobiology and genetics of Attention-Deficit/Hyperactivity Disorder (ADHD): what every clinician should know. Eur J Paediatr Neurol. 2012;16:422–33.Contini V, Rovaris DL, Victor MM, Grevet EH, Rohde LA, Bau CH. Pharmacogenetics of response to methylphenidate in adult patients with attention-deficit/hyperactivity disorder (ADHD): a systematic review. Eur Neuropsychopharmacol. 2013;23:555–60.Gardiner SJ, Begg EJ. 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A Meta-Analysis of Microarray Gene Expression in Mouse Stem Cells: Redefining Stemness

While much progress has been made in understanding stem cell (SC) function, a complete description of the molecular mechanisms regulating SCs is not yet established. This lack of knowledge is a major barrier holding back the discovery of therapeutic uses of SCs. We investigated the value of a novel meta-analysis of microarray gene expression in mouse SCs to aid the elucidation of regulatory mechanisms common to SCs and particular SC types.We added value to previously published microarray gene expression data by characterizing the promoter type likely to regulate transcription. Promoters of up-regulated genes in SCs were characterized in terms of alternative promoter (AP) usage and CpG-richness, with the aim of correlating features known to affect transcriptional control with SC function. We found that SCs have a higher proportion of up-regulated genes using CpG-rich promoters compared with the negative controls. Comparing subsets of SC type with the controls a slightly different story unfolds. The differences between the proliferating adult SCs and the embryonic SCs versus the negative controls are statistically significant. Whilst the difference between the quiescent adult SCs compared with the negative controls is not. On examination of AP usage, no difference was observed between SCs and the controls. However, comparing the subsets of SC type with the controls, the quiescent adult SCs are found to up-regulate a larger proportion of genes that have APs compared to the controls and the converse is true for the proliferating adult SCs and the embryonic SCs.These findings suggest that looking at features associated with control of transcription is a promising future approach for characterizing “stemness” and that further investigations of stemness could benefit from separate considerations of different SC states. For example, “proliferating-stemness” is shown here, in terms of promoter usage, to be distinct from “quiescent-stemness”