Tidal Truncation of Circumplanetary Discs

We analyse some properties of circumplanetary discs. Flow through such discs may provide most of the mass to gas giant planets, and such discs are likely sites for the formation of regular satellites. We model these discs as accretion discs subject to the tidal forces of the central star. The tidal torques from the star remove the disc angular momentum near the disc outer edge and permit the accreting disc gas to lose angular momentum at the rate appropriate for steady accretion. Circumplanetary discs are truncated near the radius where periodic ballistic orbits cross, where tidal forces on the disc are strong. This radius occurs at approximately 0.4 r_H for the planet Hill radius r_H. During the T Tauri stage of disc accretion, the disc is fairly thick with aspect ratio H/r > 0.2 and the disc edge tapering occurs over a radial scale ~ H ~ 0.1 r_H. For a circular or slightly eccentric orbit planet, no significant resonances lie within the main body of the disc. Tidally driven waves involving resonances nonetheless play an important role in truncating the disc, especially when it is fairly thick. We model the disc structure using one dimensional time-dependent and steady-state models and also two dimensional SPH simulations. The circumplanetary disc structure depends on the variation of the disc turbulent viscosity with radius and is insensitive to the angular distribution of the accreting gas. Dead zones may occur within the circumplanetary disc and result in density structures. If the disc is turbulent throughout, the predicted disc structure near the location of the regular Jovian and Saturnian satellites is smooth with no obvious feature that would favor formation at their current locations.Comment: Accepted for publication in MNRA

Investigating the beneficial traits of Trichoderma hamatum GD12 for sustainable agriculture : insights from genomics

Trichoderma hamatum strain GD12 is unique in that it can promote plant growth, activate biocontrol against pre- and post-emergence soil pathogens and can induce systemic resistance to foliar pathogens. This study extends previous work in lettuce to demonstrate that GD12 can confer beneficial agronomic traits to other plants, providing examples of plant growth promotion in the model dicot, Arabidopsis thaliana and induced foliar resistance to Magnaporthe oryzae in the model monocot rice. We further characterize the lettuce-T. hamatum interaction to show that bran extracts from GD12 and an N-acetyl-β-D-glucosamindase-deficient mutant differentially promote growth in a concentration dependent manner, and these differences correlate with differences in the small molecule secretome. We show that GD12 mycoparasitises a range of isolates of the pre-emergence soil pathogen Sclerotinia sclerotiorum and that this interaction induces a further increase in plant growth promotion above that conferred by GD12. To understand the genetic potential encoded by T. hamatum GD12 and to facilitate its use as a model beneficial organism to study plant growth promotion, induced systemic resistance and mycoparasitism we present de novo genome sequence data. We compare GD12 with other published Trichoderma genomes and show that T. hamatum GD12 contains unique genomic regions with the potential to encode novel bioactive metabolites that may contribute to GD12's agrochemically important traits. Read Full Tex

Principals' reports of adults' alcohol use in Australian secondary schools

Background - Schools provide opportunities for parents and the wider community to connect and support the physical and emotional wellbeing of their children. Schools therefore have the potential to play a role in the socialisation of alcohol use through school policies and practices regarding consumption of alcohol by adults at school events in the presence of children. Methods - This survey was undertaken to a) compare the extent to which alcohol is used at secondary school events, when children are present, in the states of New South Wales (NSW) and Victoria (VIC), Australia; b) describe principals’ level of agreement with these practices; c) their awareness of state policies on this issue; and d) the predictors of such events. A random sample of secondary schools, stratified to represent metropolitan and non-metropolitan schools were invited to participate. Bivariate and multivariate analysis were conducted with p values < 0.05 considered significant. Results - A total of 241 (43 %) schools consented to participate in the study. Fifteen percent of participating NSW schools and 57 % of VIC schools held at least one event in which alcohol was consumed by adults in the presence of children in the year before the survey. Of the 100 reported events, 78 % were Year 12 graduation dinners, and 18 % were debutante balls. Compared to NSW principals, VIC principals were significantly more likely to agree with the use of alcohol at these events; significantly less likely to be aware of their state education department policy on this issue; have a policy at their own school or support policy that prohibits alcohol use at such events; and less likely to report having enough Information to make decisions about this. Conclusions - There is a growing focus on adults’ use of alcohol at school events when children are present. Schools can play an important role in educating and socialising children about alcohol via both the curriculum and policies regarding adults’ alcohol use at school events. Findings from this study suggest education department and school-based policies that prohibit or restrict the use of alcohol, are significant predictors of adults’ alcohol use at school events when children are present

Monocytes and macrophages, implications for breast cancer migration and stem cell-like activity and treatment

Macrophages are a major cellular constituent of the tumour stroma and contribute to breast cancer prognosis. The precise role and treatment strategies to target macrophages remain elusive. As macrophage infiltration is associated with poor prognosis and high grade tumours we used the THP-1 cell line to model monocyte-macrophage differentiation in co-culture with four breast cancer cell lines (MCF7, T47D, MDA-MB-231, MDA-MB-468) to model in vivo cellular interactions. Polarisation into M1 and M2 subtypes was confirmed by specific cell marker expression of ROS and HLA-DR, respectively. Co-culture with all types of macrophage increased migration of ER-positive breast cancer cell lines, while M2-macrophages increased mammosphere formation, compared to M1-macrophages, in all breast cancer cells lines. Treatment of cells with Zoledronate in co-culture reduced the “pro-tumourigenic” effects (increased mammospheres/migration) exerted by macrophages. Direct treatment of breast cancer cells in homotypic culture was unable to reduce migration or mammosphere formation. Macrophages promote “pro-tumourigenic” cellular characteristics of breast cancer cell migration and stem cell activity. Zoledronate targets macrophages within the microenvironment which in turn, reduces the “pro-tumourigenic” characteristics of breast cancer cells. Zoledronate offers an exciting new treatment strategy for both primary and metastatic breast cancer

The acceptance and kinetic resolution of alpha-Methyl Substituted Aldehydes by Norcoclaurine Synthase

Norcoclaurine synthase (NCS) catalyzes a stereoselective Pictet-Spengler reaction to give the key intermediate, (S)-norcoclaurine in benzylisoquinoline alkaloid (BIA) biosynthesis. This family of alkaloids contains many bioactive molecules including morphine and berberine. Recently, NCS has been demonstrated to accept a variety of aldehydes and some ketones as substrates, leading to a range of chiral tetrahydroisoquinoline (THIQ) products. Here, we report the unusual acceptance of a-substituted aldehydes, in particular a-methyl substituted aldehydes, by wild-type Thalictrum flavum NCS (Δ33TfNCS) to give THIQ products. Moreover, the kinetic resolution of several a-substituted aldehydes to give THIQs with two defined chiral centers in a single step with high conversions was achieved. Several dopamine analogues were also accepted as substrates and reactions were amenable to scale-up. Active site mutants of TfNCS were then used which demonstrated the potential to enhance the stereoselectivities in the reaction and improve yields. Rationale for the acceptance of these substrates and improved activity with different mutants has been gained from a co-crystallized structure of Δ33TfNCS with a non-productive mimic of a reaction intermediate bound in the active site. Finally, molecular dynamics simulations were performed to study the binding of dopamine and an a-substituted aldehyde and provided further insight into the reaction with these substrates

Predictors of invertebrate biomass and rate of advancement of invertebrate phenology across eight sites in the North American Arctic

Average annual temperatures in the Arctic increased by 2–3 °C during the second half of the twentieth century. Because shorebirds initiate northward migration to Arctic nesting sites based on cues at distant wintering grounds, climate-driven changes in the phenology of Arctic invertebrates may lead to a mismatch between the nutritional demands of shorebirds and the invertebrate prey essential for egg formation and subsequent chick survival. To explore the environmental drivers afecting invertebrate availability, we modeled the biomass of invertebrates captured in modifed Malaise-pitfall traps over three summers at eight Arctic Shorebird Demographics Network sites as a function of accumulated degree-days and other weather variables. To assess climate-driven changes in invertebrate phenology, we used data from the nearest long-term weather stations to hindcast invertebrate availability over 63 summers, 1950–2012. Our results confrmed the importance of both accumulated and daily temperatures as predictors of invertebrate availability while also showing that wind speed negatively afected invertebrate availability at the majority of sites. Additionally, our results suggest that seasonal prey avail ability for Arctic shorebirds is occurring earlier and that the potential for trophic mismatch is greatest at the northernmost sites, where hindcast invertebrate phenology advanced by approximately 1–2.5 days per decade. Phenological mismatch could have long-term population-level efects on shorebird species that are unable to adjust their breeding schedules to the increasingly earlier invertebrate phenologies.publishedVersio

Global gene expression analysis of apple fruit development from the floral bud to ripe fruit

<p>Abstract</p> <p>Background</p> <p>Apple fruit develop over a period of 150 days from anthesis to fully ripe. An array representing approximately 13000 genes (15726 oligonucleotides of 45–55 bases) designed from apple ESTs has been used to study gene expression over eight time points during fruit development. This analysis of gene expression lays the groundwork for a molecular understanding of fruit growth and development in apple.</p> <p>Results</p> <p>Using ANOVA analysis of the microarray data, 1955 genes showed significant changes in expression over this time course. Expression of genes is coordinated with four major patterns of expression observed: high in floral buds; high during cell division; high when starch levels and cell expansion rates peak; and high during ripening. Functional analysis associated cell cycle genes with early fruit development and three core cell cycle genes are significantly up-regulated in the early stages of fruit development. Starch metabolic genes were associated with changes in starch levels during fruit development. Comparison with microarrays of ethylene-treated apple fruit identified a group of ethylene induced genes also induced in normal fruit ripening. Comparison with fruit development microarrays in tomato has been used to identify 16 genes for which expression patterns are similar in apple and tomato and these genes may play fundamental roles in fruit development. The early phase of cell division and tissue specification that occurs in the first 35 days after pollination has been associated with up-regulation of a cluster of genes that includes core cell cycle genes.</p> <p>Conclusion</p> <p>Gene expression in apple fruit is coordinated with specific developmental stages. The array results are reproducible and comparisons with experiments in other species has been used to identify genes that may play a fundamental role in fruit development.</p

The Peculiar Debris Disk of HD 111520 as Resolved by the Gemini Planet Imager

Using the Gemini Planet Imager (GPI), we have resolved the circumstellar debris disk around HD 111520 at a projected range of ~30-100 AU in both total and polarized $H$-band intensity. The disk is seen edge-on at a position angle of ~165$^{\circ}$ along the spine of emission. A slight inclination or asymmetric warping are covariant and alters the interpretation of the observed disk emission. We employ 3 point spread function (PSF) subtraction methods to reduce the stellar glare and instrumental artifacts to confirm that there is a roughly 2:1 brightness asymmetry between the NW and SE extension. This specific feature makes HD 111520 the most extreme examples of asymmetric debris disks observed in scattered light among similar highly inclined systems, such as HD 15115 and HD 106906. We further identify a tentative localized brightness enhancement and scale height enhancement associated with the disk at ~40 AU away from the star on the SE extension. We also find that the fractional polarization rises from 10 to 40% from 0.5" to 0.8" from the star. The combination of large brightness asymmetry and symmetric polarization fraction leads us to believe that an azimuthal dust density variation is causing the observed asymmetry.Comment: 9 pages, 8 Figures, 1 table, Accepted to Ap

A self‐assembled anion‐binding cryptand for the highly selective liquid‐liquid extraction of phosphate anions

The ligands L1 and L2 form trinuclear self‐assembled complexes with Cu2+ (i.e. [(L1)2Cu3]6+ or [(L2)2Cu3]6+) both of which act as a host to a variety of anions. Inclusion of long aliphatic chains on these ligands allows the assemblies to extract anions from aqueous media into organic solvents. Phosphate can be removed from water efficiently and highly selectively, even in the presence of other anions