Revision of the Nomenclature of the Differential Host-Pathogen Interactions of Venturia inaequalis and Malus

The apple scab (Venturia inaequalis–Malus) pathosystem was one of the first systems for which Flor\u27s concept of gene-for-gene (GfG) relationships between the host plant and the pathogen was demonstrated. There is a rich resource of host resistance genes present in Malus germplasm that could potentially be marshalled to confer durable resistance against this most important apple disease. A comprehensive understanding of the host-pathogen interactions occurring in this pathosystem is a prerequisite for effectively manipulating these host resistance factors. An accurate means of identification of specific resistance and consistent use of gene nomenclature is critical for this process. A set of universally available, differentially resistant hosts is described, which will be followed by a set of defined pathogen races at a later stage. We review pertinent aspects of the history of apple scab research, describe the current status and future directions of this research, and resolve some outstanding issues

Insights into the Second Law of Thermodynamics from Anisotropic Gas-Surface Interactions

Thermodynamic implications of anisotropic gas-surface interactions in a closed molecular flow cavity are examined. Anisotropy at the microscopic scale, such as might be caused by reduced-dimensionality surfaces, is shown to lead to reversibility at the macroscopic scale. The possibility of a self-sustaining nonequilibrium stationary state induced by surface anisotropy is demonstrated that simultaneously satisfies flux balance, conservation of momentum, and conservation of energy. Conversely, it is also shown that the second law of thermodynamics prohibits anisotropic gas-surface interactions in "equilibrium", even for reduced dimensionality surfaces. This is particularly startling because reduced dimensionality surfaces are known to exhibit a plethora of anisotropic properties. That gas-surface interactions would be excluded from these anisotropic properties is completely counterintuitive from a causality perspective. These results provide intriguing insights into the second law of thermodynamics and its relation to gas-surface interaction physics.Comment: 28 pages, 11 figure

The Physics of Star Cluster Formation and Evolution

© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00689-4.Star clusters form in dense, hierarchically collapsing gas clouds. Bulk kinetic energy is transformed to turbulence with stars forming from cores fed by filaments. In the most compact regions, stellar feedback is least effective in removing the gas and stars may form very efficiently. These are also the regions where, in high-mass clusters, ejecta from some kind of high-mass stars are effectively captured during the formation phase of some of the low mass stars and effectively channeled into the latter to form multiple populations. Star formation epochs in star clusters are generally set by gas flows that determine the abundance of gas in the cluster. We argue that there is likely only one star formation epoch after which clusters remain essentially clear of gas by cluster winds. Collisional dynamics is important in this phase leading to core collapse, expansion and eventual dispersion of every cluster. We review recent developments in the field with a focus on theoretical work.Peer reviewe

Ultrasonography of the eye and orbit

With development of portable ultrasound units, ultrasonography has grown significantly in many aspects of equine practice. Ocular ultrasonography is indicated in cases of corneal edema, cataracts, or intraocular hemorrhage, because the normally clear ocular media has become opaque and visualization of the interior structures of the globe is restricted. Technological advancements have introduced various methods of ultrasonography to the field of ophthalmology. Color Doppler technique is used to visualize blood vessels and their flow characteristics within the eye and orbit. Ocular and orbital ultrasonography is usually easily performed in the standing horse following sedation, an auriculopalpebral nerve block, and the application of topical anesthetic (e.g. proparacaine, tetracaine) to the ocular surface. This chapter presents images of ultrasonographic changes in the abnormal eye. Exophthalmos and trauma are the most common indications for orbital ultrasonography

Supplementary Material for: Genomic and Metabolic Responses to Methionine-Restricted and Methionine-Restricted, Cysteine-Supplemented Diets in Fischer 344 Rat Inguinal Adipose Tissue, Liver and Quadriceps Muscle

<b><i>Background/Aims:</i></b> Methionine restriction (MR) is a dietary intervention that increases lifespan, reduces adiposity and improves insulin sensitivity. These effects are reversed by supplementation of the MR diet with cysteine (MRC). Genomic and metabolomic studies were conducted to identify potential mechanisms by which MR induces favorable metabolic effects, and that are reversed by cysteine supplementation. <b><i>Methods:</i></b> Gene expression was examined by microarray analysis and TaqMan quantitative PCR. Levels of selected proteins were measured by Western blot and metabolic intermediates were analyzed by mass spectrometry. <b><i>Results:</i></b> MR increased lipid metabolism in inguinal adipose tissue and quadriceps muscle while it decreased lipid synthesis in liver. In inguinal adipose tissue, MR not only caused the transcriptional upregulation of genes associated with fatty acid synthesis but also of <i>Lpin1</i>, <i>Pc</i>, <i>Pck1</i> and <i>Pdk1</i>, genes that are associated with glyceroneogenesis. MR also upregulated lipolysis-associated genes in inguinal fat and led to increased oxidation in this tissue, as suggested by higher levels of methionine sulfoxide and 13-HODE + 9-HODE compared to control-fed (CF) rats. Moreover, MR caused a trend toward the downregulation of inflammation-associated genes in inguinal adipose tissue. MRC reversed most gene and metabolite changes induced by MR in inguinal adipose tissue, but drove the expression of <i>Elovl6</i>, <i>Lpin1</i>, <i>Pc</i>, and <i>Pdk1</i> below CF levels. In liver, MR decreased levels of a number of long-chain fatty acids, glycerol and glycerol-3-phosphate corresponding with the gene expression data. Although MR increased the expression of genes associated with carbohydrate metabolism, levels of glycolytic intermediates were below CF levels. MR, however, stimulated gluconeogenesis and ketogenesis in liver tissue. As previously reported, sulfur amino acids derived from methionine were decreased in liver by MR, but homocysteine levels were elevated. Increased liver homocysteine levels by MR were associated with decreased cystathionine β-synthase (CBS) protein levels and lowered vitamin B6 and 5-methyltetrahydrofolate (5MeTHF) content. Finally, MR upregulated fibroblast growth factor 21 (FGF21) gene and protein levels in both liver and adipose tissues. MRC reversed some of MR’s effects in liver and upregulated the transcription of genes associated with inflammation and carcinogenesis such as <i>Cxcl16</i>, <i>Cdh17</i>, <i>Mmp12</i>, <i>Mybl1</i>, and <i>Cav1</i> among others. In quadriceps muscle, MR upregulated lipid metabolism-associated genes and increased 3-hydroxybutyrate levels suggesting increased fatty acid oxidation as well as stimulation of gluconeogenesis and glycogenolysis in this tissue. <b><i>Conclusion:</i></b> Increased lipid metabolism in inguinal adipose tissue and quadriceps muscle, decreased triglyceride synthesis in liver and the downregulation of inflammation-associated genes are among the factors that could favor the lean phenotype and increased insulin sensitivity observed in MR rats

A proposal for the nomenclature of Venturia inaequalis races.

The Venturia inaequalis-Malus pathosystem was one of the first for which gene-for-gene relationships were demonstrated following the discovery of such relationships between Melampsora lini and flax by Flor in the 1950s. An understanding of these relationships forms the basis for monitoring pathotypes of V. inaequalis at the population level and is employed to assess the usefulness of resistance genes for breeding durable resistance to scab. These pathotypes are difficult to accommodate in the current system of nomenclature for V. inaequalis races where each new combination of avirulence alleles is assigned a simple numerical descriptor as its name. We propose a system that is better suited to the increasing complexities of combinations of genes involved in both race-specific and race-nonspecific recognition by the host, while at the same time updating the name of scab resistance loci (Rvik) and QTL loci (Qvik) to international standards. For the race-specific interactions, the basic premise is that each Rvik-AvrRvik and Qvik-AvrQvik relationship should be represented by a differential host (k), abbreviated to h(k), carrying only the specific Rvik or (major) Qvik resistance allele and an isolate of the pathogen having lost only the complementary allele at the AvrRvik or AvrQvik locus, race (k), with k representing the number of the specific interaction. Races lacking more than one avirulence gene at different loci will be identified as race (k,l,m,\u2026) and apple hosts carrying multiple scab resistance genes as host (k,l,m,\u2026). The proposed system has some continuity with the current system, but should simplify the presentation and interpretation of studies on avirulence alleles in V. inaequalis at the population level. Gene-for-gene relationships reported to date for this pathosystem are reviewed, some inconsistencies clarified, and several new interactions added. The gene-for-gene relationships of European isolates collected in the last decade have been studied in order to establish a new set of reference isolates that represent various V. inaequalis races