Global Continua of Positive Equilibria for some Quasilinear Parabolic Equation with a Nonlocal Initial Condition

This paper is concerned with a quaslinear parabolic equation including a nonlinear nonlocal initial condition. The problem arises as equilibrium equation in population dynamics with nonlinear diffusion. We make use of global bifurcation theory to prove existence of an unbounded continuum of positive solutions

Adaptive genomic structural variation in the grape powdery mildew pathogen, Erysiphe necator.

BackgroundPowdery mildew, caused by the obligate biotrophic fungus Erysiphe necator, is an economically important disease of grapevines worldwide. Large quantities of fungicides are used for its control, accelerating the incidence of fungicide-resistance. Copy number variations (CNVs) are unbalanced changes in the structure of the genome that have been associated with complex traits. In addition to providing the first description of the large and highly repetitive genome of E. necator, this study describes the impact of genomic structural variation on fungicide resistance in Erysiphe necator.ResultsA shotgun approach was applied to sequence and assemble the genome of five E. necator isolates, and RNA-seq and comparative genomics were used to predict and annotate protein-coding genes. Our results show that the E. necator genome is exceptionally large and repetitive and suggest that transposable elements are responsible for genome expansion. Frequent structural variations were found between isolates and included copy number variation in EnCYP51, the target of the commonly used sterol demethylase inhibitor (DMI) fungicides. A panel of 89 additional E. necator isolates collected from diverse vineyard sites was screened for copy number variation in the EnCYP51 gene and for presence/absence of a point mutation (Y136F) known to result in higher fungicide tolerance. We show that an increase in EnCYP51 copy number is significantly more likely to be detected in isolates collected from fungicide-treated vineyards. Increased EnCYP51 copy numbers were detected with the Y136F allele, suggesting that an increase in copy number becomes advantageous only after the fungicide-tolerant allele is acquired. We also show that EnCYP51 copy number influences expression in a gene-dose dependent manner and correlates with fungal growth in the presence of a DMI fungicide.ConclusionsTaken together our results show that CNV can be adaptive in the development of resistance to fungicides by providing increasing quantitative protection in a gene-dosage dependent manner. The results of this work not only demonstrate the effectiveness of using genomics to dissect complex traits in organisms with very limited molecular information, but also may have broader implications for understanding genomic dynamics in response to strong selective pressure in other pathogens with similar genome architectures

Comparative metabolism as a key driver of wildlife species sensitivity to human and veterinary pharmaceuticals

Human and veterinary drug development addresses absorption, distribution, metabolism, elimination and toxicology (ADMET) of the Active Pharmaceutical Ingredient (API) in the target species. Metabolism is an important factor in controlling circulating plasma and target tissue API concentrations and in generating metabolites which are more easily eliminated in bile, faeces and urine. The essential purpose of xenobiotic metabolism is to convert lipid-soluble, non-polar and non-excretable chemicals into water soluble, polar molecules that are readily excreted. Xenobiotic metabolism is classified into Phase I enzymatic reactions (which add or expose reactive functional groups on xenobiotic molecules), Phase II reactions (resulting in xenobiotic conjugation with large water-soluble, polar molecules) and Phase III cellular efflux transport processes. The human-fish plasma model provides a useful approach to understanding the pharmacokinetics of APIs (e.g. diclofenac, ibuprofen and propranolol) in freshwater fish, where gill and liver metabolism of APIs have been shown to be of importance. By contrast, wildlife species with low metabolic competency may exhibit zero-order metabolic (pharmacokinetic) profiles and thus high API toxicity, as in the case of diclofenac and the dramatic decline of vulture populations across the Indian subcontinent. A similar threat looms for African Cape Griffon vultures exposed to ketoprofen and meloxicam, recent studies indicating toxicity relates to zero-order metabolism (suggesting P450 Phase I enzyme system or Phase II glucuronidation deficiencies). While all aspects of ADMET are important in toxicity evaluations, these observations demonstrate the importance of methods for predicting API comparative metabolism as a central part of environmental risk assessment

'The Additional Attraction of Affliction': Disability, Sex, and Genre Trouble in Barchester Towers

WHILE THERE IS NEVER any serious doubt that Mr. Arabin, clergyman hero of Anthony Trollope’s Barchester Towers (1857), is destined to marry our heroine, Eleanor Bold, there are moments in the novel when he is all but overcome by the charms of Signora Madeline Neroni, most beautiful and most amoral member of the rackety Stanhope family. Having spent her wicked youth in Italy, where her father has been taking an extended leave of absence from his clerical duties – curtailed only by a peremptory summons from the new Bishop – Madeline is entertaining herself during her enforced stay in Barchester by waging a concerted campaign of seduction, intending “to have parsons at her feet” (86–87; vol. 1, ch. 10). The fact that she never leaves her sofa does nothing to impede her success in this regard: although Madeline is described by the narrator as “a helpless, hopeless cripple” (270; vol. 1, ch. 27), every man she meets is shown to fall under her spell. In fact, when Arabin finds himself “mak[ing] comparisons between her and Eleanor Bold, not always in favour of the latter,” he reflects that Madeline is “the more lovely woman of the two, and had also the additional attraction of her affliction; for to him it was an attraction” (74; vol. 2, ch. 34). Far from diminishing her “loveliness,” Madeline’s disability actually heightens her sexual appeal for Arabin

Strigolactone synthesis is ancestral in land plants, but canonical strigolactone signalling is a flowering plant innovation

Background Strigolactones (SLs) are an important class of carotenoid-derived signalling molecule in plants, which function both as exogenous signals in the rhizosphere and as endogenous plant hormones. In flowering plants, SLs are synthesized by a core pathway of four enzymes and are perceived by the DWARF14 (D14) receptor, leading to degradation of SMAX1-LIKE7 (SMXL7) target proteins in a manner dependent on the SCFMAX2 ubiquitin ligase. The evolutionary history of SLs is poorly understood, and it is not clear whether SL synthesis and signalling are present in all land plant lineages, nor when these traits evolved. Results We have utilized recently-generated genomic and transcriptomic sequences from across the land plant clade to resolve the origin of each known component of SL synthesis and signalling. We show that all enzymes in the core SL synthesis pathway originated at or before the base of land plants, consistent with the previously observed distribution of SLs themselves in land plant lineages. We also show that the late-acting enzyme LATERAL BRANCHING OXIDOREDUCTASE (LBO) may be considerably more ancient than previously thought. We perform a detailed phylogenetic analysis of SMXL proteins and show that specific SL target proteins only arose in flowering plants. We also assess diversity and protein structure in the SMXL family, identifying several previously unknown clades. Conclusions Overall, our results suggest that SL synthesis is much more ancient than canonical SL signalling, consistent with the idea that SLs first evolved as rhizosphere signals and were only recruited much later as hormonal signals

Forbidden Fruit: Dominance Relationships and the Control of Shoot Architecture

Plants continually integrate environmental information to make decisions about their development. Correlative controls, in which one part of the plant regulates the growth of another, form an important class of regulatory mechanism, but their study has been neglected, and their molecular basis remains unclear. In this article, we examine the role of negative correlative controls or ‘dominance’ phenomena in the regulation of shoot architecture. Apical dominance, in which actively growing shoot branches inhibit the growth of other branches, is perhaps the most famous example of this. We discuss the recent progress made in understanding the mechanistic basis for apical dominance and three plausible models for shoot branching control. We then use the apical dominance paradigm to explore other dominance phenomena, including seed–seed inhibition (carpic dominance), seed‐to‐meristem inhibition, and the control of maternal senescence by seeds. We propose that apical and carpic dominance may share a common mechanistic basis rooted in auxin transport canalisation. Conversely, we conclude that seed‐to‐meristem inhibition and seed‐driven senescence may not be ‘true’ correlative controls, but rather more complex phenomena in which seed set plays a permissive rather than instructive role. Overall, we attempt to develop a coherent framework for understanding the developmental and regulatory mechanisms that control shoot architecture and provide new insights into the end of flowering, fruiting, and growth

Ehrenfest relations and magnetoelastic effects in field-induced ordered phases

Magnetoelastic properties in field-induced magnetic ordered phases are studied theoretically based on a Ginzburg-Landau theory. A critical field for the field-induced ordered phase is obtained as a function of temperature and pressure, which determine the phase diagram. It is found that magnetic field dependence of elastic constant decreases discontinuously at the critical field, Hc, and that it decreases linearly with field in the ordered phase (H>Hc). We found an Ehrenfest relation between the field dependence of the elastic constant and the pressure dependence of critical field. Our theory provides the theoretical form for magnetoelastic properties in field- and pressure-induced ordered phases.Comment: 7 pages, 3 figure

Uncertainty in exposure to air pollution

Abstract onl