The Regulation of Maize Leaf Phosphoenolpyruvate Carboxylase

When this project started, it had been shown that the PEP carboxylase of CAM plants was regulated by a reversible phosphorylation. The main aim of this work was therefore to examine the hypothesis that PEP carboxylase from maize leaves was regulated by phosphorylation in response to light or darkness

Exploring the formation by core accretion and the luminosity evolution of directly imaged planets: The case of HIP 65426 b

A low-mass companion to the two-solar mass star HIP65426 has recently been detected by SPHERE at around 100 au from its host. Explaining the presence of super-Jovian planets at large separations, as revealed by direct imaging, is currently an open question. We want to derive statistical constraints on the mass and initial entropy of HIP65426b and to explore possible formation pathways of directly imaged objects within the core-accretion paradigm, focusing on HIP65426b. Constraints on the planet's mass and post-formation entropy are derived from its age and luminosity combined with cooling models. For the first time, the results of population synthesis are also used to inform the results. Then, a formation model that includes N-body dynamics with several embryos per disc is used to study possible formation histories and the properties of possible additional companions. Finally, the outcomes of two- and three-planet scattering in the post-disc phase are analysed, taking tides into account. The mass of HIP65426b is found to be Mp = 9.9 +1.1 -1.8 MJ using the hot population and Mp = 10.9 +1.4 -2.0 MJ with the cold-nominal population. Core formation at small separations from the star followed by outward scattering and runaway accretion at a few hundred AU succeeds in reproducing the mass and separation of HIP65426b. Alternatively, systems having two or more giant planets close enough to be on an unstable orbit at disc dispersal are likely to end up with one planet on a wide HIP65426b-like orbit with a relatively high eccentricity (>~ 0.5). If this scattering scenario explains its formation, HIP65426b is predicted to have a high eccentricity and to be accompanied by one or several roughly Jovian-mass planets at smaller semi-major axes, which also could have a high eccentricity. This could be tested by further direct-imaging as well as radial-velocity observations.Comment: 17 pages, 11 figures. A&A in press. Bern EXoplanet cooling curves (BEX) available upon request. v2: Language and other minor changes; Fig. 4 now has labels summarising a possible formation pathway discussed in the tex

Examining the terminology of race issues in assessments for international exchange students

This study examined assignments by students from a university in Scotland and a university in the USA, and explored the terminology used by student when referring to race issues in assignments linked to practice. The findings suggest the terminology of race issues in assessments may be inappropriate for students because they allow racism to be marginalized from practice or presented in a way that conveys little analysis

The Regulation of Aggrecanase ADAMTS-4 Expression in Human Achilles Tendon and tendon-Derived Cells

Several members of the ADAMTS (A Disintegrin And Metalloproteinase with ThromboSpondin motifs) family have been identified as aggrecanases, whose substrates include versican, the principal large proteoglycan in the tendon extracellular matrix. We have characterized the expression of ADAMTS-4 in human Achilles tendon and tendon-derived cells. ADAMTS-4 mRNA levels were higher in ruptured tendon compared with normal tendon or chronic painful tendinopathy. In tissue extracts probed by Western blotting, mature ADAMTS-4 (68 kDa) was detected only in ruptured tendons, while processed ADAMTS-4 (53 kDa) was detected also in chronic painful tendinopathy and in normal tendon. In cultured Achilles tendon cells, transforming growth factor-ß (TGF-ß) stimulated ADAMTS-4 mRNA expression (typically 20-fold after 24 h), while interleukin-1 induced a smaller, shorter-term stimulation which synergised markedly with that induced by TGF-ß. Increased levels of immunoreactive proteins consistent with mature and processed forms of ADAMTS-4 were detected in TGF-ß-stimulated cells. ADAMTS-4 mRNA was expressed at higher levels by tendon cells in collagen gels than in monolayer cultures. In contrast, the expression of ADAMTS-1 and -5 mRNA was lower in collagen gels compared with monolayers, and these mRNA showed smaller or opposite responses to growth factors and cytokines compared with that of ADAMTS-4 mRNA. We conclude that both ADAMTS-4 mRNA and ADAMTS-4 protein processing may be differentially regulated in normal and damaged tendons and that both the matrix environment and growth factors such as TGF-ß are potentially important factors controlling ADAMTS aggrecanase activities in tendon pathology

Benthic oxygen exchange in a live coralline algal bed and an adjacent sandy habitat: an eddy covariance study

Coralline algal (maerl) beds are widespread, slow-growing, structurally complex perennial habitats that support high biodiversity, yet are significantly understudied compared to seagrass beds or kelp forests. We present the first eddy covariance (EC) study on a live maerl bed, assessing the community benthic gross primary productivity (GPP), respiration (R), and net ecosystem metabolism (NEM) derived from diel EC time series collected during 5 seasonal measurement campaigns in temperate Loch Sween, Scotland. Measurements were also carried out at an adjacent (~20 m distant) permeable sandy habitat. The O2 exchange rate was highly dynamic, driven by light availability and the ambient tidally-driven flow velocity. Linear relationships between the EC O2 fluxes and available light indicate that the benthic phototrophic communities were lightlimited. Compensation irradiance (Ec) varied seasonally and was typically ~1.8-fold lower at the maerl bed compared to the sand. Substantial GPP was evident at both sites; however, the maerl bed and the sand habitat were net heterotrophic during each sampling campaign. Additional inputs of ~4 and ~7 mol m-2 yr-1 of carbon at the maerl bed and sand site, respectively, were required to sustain the benthic O2 demand. Thus, the 2 benthic habitats efficiently entrap organic carbon and are sinks of organic material in the coastal zone. Parallel deployment of 0.1 m2 benthic chambers during nighttime revealed O2 uptake rates that varied by up to ~8-fold between replicate chambers (from -0.4 to -3.0 mmol O2 m-2 h-1; n = 4). However, despite extensive O2 flux variability on meter horizontal scales, mean rates of O2 uptake as resolved in parallel by chambers and EC were typically within 20% of one another

Dispersal of protoplanetary discs: How stellar properties and the local environment determine the pathway of evolution

We study the evolution and final dispersal of protoplanetary discs that evolve under the action of internal and external photoevaporation, and different degrees of viscous transport. We identify five distinct dispersal pathways, which are i) very long lived discs ($>20\,$Myr), ii) inside-out dispersal where internal photoevaporation dominates and opens inner holes, iii) outside-in dispersal where external photoevaporation dominates through disc truncation and two intermediate regimes characterised by lingering material in the inner disc with the outer disc dispersed predominantly by either internal or external photoevaporation. We determine how the lifetime, relative impact of internal and external winds and clearing pathway varies over a wide, plausible, parameter space of stellar/disc/radiation properties. There are a number of implications, for example in high UV environments because the outer disc lifetime is shorter than the time-scale for clearing the inner disc we do not expect transition discs to be common, which appears to be reflected in the location of transition disc populations towards the Orion Nebular Cluster. Irrespective of environment, we find that ongoing star formation is required to reproduce observed disc fractions as a function of stellar cluster age. This work demonstrates the importance of including both internal and external winds for understanding protoplanetary disc evolution.Comment: Submitted to MNRAS. 19 pages, 15 figure

Infection with a Virulent Strain of Wolbachia Disrupts Genome Wide-Patterns of Cytosine Methylation in the Mosquito Aedes aegypti

BACKGROUND Cytosine methylation is one of several reversible epigenetic modifications of DNA that allow a greater flexibility in the relationship between genotype and phenotype. Methylation in the simplest models dampens gene expression by modifying regions of DNA critical for transcription factor binding. The capacity to methylate DNA is variable in the insects due to diverse histories of gene loss and duplication of DNA methylases. Mosquitoes like Drosophila melanogaster possess only a single methylase, DNMT2. DESCRIPTION Here we characterise the methylome of the mosquito Aedes aegypti and examine its relationship to transcription and test the effects of infection with a virulent strain of the endosymbiont Wolbachia on the stability of methylation patterns. CONCLUSION We see that methylation in the A. aegypti genome is associated with reduced transcription and is most common in the promoters of genes relating to regulation of transcription and metabolism. Similar gene classes are also methylated in aphids and honeybees, suggesting either conservation or convergence of methylation patterns. In addition to this evidence of evolutionary stability, we also show that infection with the virulent wMelPop Wolbachia strain induces additional methylation and demethylation events in the genome. While most of these changes seem random with respect to gene function and have no detected effect on transcription, there does appear to be enrichment of genes associated with membrane function. Given that Wolbachia lives within a membrane-bound vacuole of host origin and retains a large number of genes for transporting host amino acids, inorganic ions and ATP despite a severely reduced genome, these changes might represent an evolved strategy for manipulating the host environments for its own gain. Testing for a direct link between these methylation changes and expression, however, will require study across a broader range of developmental stages and tissues with methods that detect splice variants.This research was supported by The National Health and Medical Research Council of Australia. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Charmonium suppression from purely geometrical effects

The extend to which geometrical effects contribute to the production and suppression of the $J/\psi$ and $q\bar{q}$ minijet pairs in general is investigated for high energy heavy ion collisions at SPS, RHIC and LHC energies. For the energy range under investigation, the geometrical effects referred to are shadowing and anti-shadowing, respectively. Due to those effects, the parton distributions in nuclei deviate from the naive extrapolation from the free nucleon result; $f_{A}\neq A f_{N}$. The strength of the shadowing/anti-shadowing effect increases with the mass number. The consequences of gluonic shadowing effects for the $x_F$ distribution of $J/\psi$'s at $\sqrt s =20$ GeV, $\sqrt s =200$ GeV and $\sqrt s =6$ TeV are calculated for some relevant combinations of nuclei, as well as the $p_T$ distribution of minijets at midrapidity for $N_f=4$ in the final state.Comment: corrected some typos, improved shadowing ratio

Resporulation of Calcium Alginate Encapsulated Metarhizium anisopliae on Metham - Fumigated Soil and Infectivity on Larvae of Tenebrio molitor

Metarhizium anisopliae infects and kills a large range of insects and is a promising biocontrol agent to manage soil insects, such as wireworm in sweetpotato. The presence of other soil microbes, which exhibit competitive fungistasis, may inhibit the establishment of M. anisopliae in soil. Microbially depleted soil, for example, sterilized soil, has been shown to improve the resporulation of the fungus from nutrient-fortified M. anisopliae. Prior to planting, sweetpotato plant beds can be disinfected with fumigants, such as Metham®, to control soil-borne pests and weeds. Metham® is a broad-spectrum soil microbial suppressant; however, its effect on Metarhizium spp. is unclear. In the research presented here, fungal resporulation was examined in Metham®-fumigated soil and the infectivity of the resulting granule sporulation was evaluated on mealworm, as a proxy for wireworm. The fungal granules grown on different soil treatments (fumigated, field and pasteurized soil) resporulated profusely (for example, 4.14 × 107 (±2.17 × 106) conidia per granule on fumigated soil), but the resporulation was not significantly different among the three soil treatments. However, the conidial germination of the resporulated granules on fumigated soil was >80%, which was significantly higher than those on pasteurized soil or field soil. The resporulated fungal granules were highly infective, causing 100% insect mortality 9 days after the inoculation, regardless of soil treatments. The results from this research show that the fungal granules applied to soils could be an infective inoculant in sweetpotato fields in conjunction with soil fumigation. Additional field studies are required to validate these results and to demonstrate integration with current farming practice