Pathogenicity and molecular detection of nectriaceous fungi associated with black root rot of avocado

Black root rot of avocado associated with soilborne nectriaceous fungi is an aggressive disease of nursery trees and young orchards transplants, causing tree stunting, wilt, severe root necrosis, rapid decline and death within a year after planting. This study aimed to identify the fungal genera associated with the disease, determine the causal agents of black root rot, and develop a rapid molecular test for detection of key pathogens in avocado roots. A disease survey in all Australian growing regions collected 153 nectriaceous fungal isolates from roots of 91 symptomatic and healthy avocado trees and other hosts including peanut, papaya, blueberry, custard apple and grapevine. The fungal isolates were identified with phylogenetic analyses of ITS, β-tubulin and Histone H3 sequenced genes. Six genera were found associated with black root rot; Calonectria, Cylindrocladiella, Dactylonectria, Gliocladiopsis, Ilyonectria and Mariannaea. Glasshouse pathogenicity tests on 3–6 month-old avocado cv. Reed seedlings determined Calonectria ilicicola to be an aggressive pathogen, causing stunting and death within 5 weeks of inoculation. C. ilicicola isolated from peanut, papaya and custard apple also caused black root rot in avocado, demonstrating a broad host range. Calonectria sp. from blueberry and Dactylonectria macrodidyma, D. novozelandica, D. pauciseptata and D. anthuriicola from avocado caused significant root rot but not stunting within 5–9 weeks. Ilyonectria sp. from grapevine, and Cylindrocladiella pseudoinfestans, Gliocladiopsis peggii and Ilyonectria sp. isolates from avocado were determined to be non-pathogenic. Three loopmediated isothermal amplification (LAMP) assays were developed for the detection of C. ilicicola, D. macrodidyma and the Dactylonectria genus. The assays were sensitive and specific at DNA concentrations of 1 pg/µl, 0.01 ng/µl and 0.1ng/µl for C. ilicicola, D. macrodidyma, and Dactylonectria spp. respectively. Detection in avocado roots averaged from 12–26 min for C. ilicicola and D. macrodidyma and 14–30 min for Dactylonectria spp

Combined spatially resolved operando spectroscopy: New insights into kinetic oscillations of CO oxidation on Pd/γ-Al 2O3

Spatially resolved, combined energy dispersive EXAFS (EDE) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements have been performed over a fixed catalyst bed of Pd/γ-Al 2 O 3 during kinetic oscillations of CO oxidation. The kinetic oscillations of CO oxidation over Pd (or for that matter Pt or Rh) catalysts are a complicated phenomenon that require characterisation techniques with high time resolution and spatial resolution in order to make links between catalyst structure and surface reactivity. By measuring the extent of Pd oxidation at the nanoparticle surface, from Pd K-edge EDE, and matching this with the CO coverage, from DRIFTS spectra, at multiple positions of the fixed bed reactor it is found that the majority of the catalyst undergoes a sharp transition from the CO poisoned catalyst to the highly active, oxidised Pd surface. This transition occurs initially at the end of the catalyst bed, nearest the outlet, and propagates upstream with increasing temperature of the reactor. The oscillations in Pd surface oxide formation and CO coverage are observed only in the first ∼1 mm of the bed, which gives rise to oscillations in CO 2 and O 2 concentrations observed by end-pipe mass spectrometry after the light-off temperature. The catalyst initially exists as less active, CO poisoned metallic Pd nanoparticles before light-off which transition to a highly active state after light-off when the Pd nanoparticle surface becomes dominated by chemisorbed oxygen. Kinetic oscillations only occur at the front of the catalyst bed where there is sufficient concentration of CO in the gas phase to compete with O 2 for adsorption sites at the catalyst surface. We demonstrate the complex nature of the evolving catalyst structure and surface reactivity during catalytic operation and the need for spatially resolved operando methods for understanding and optimising catalyst technologies

Commercial hospitality in destination experiences: McDonald's and tourists' consumption of space

This paper examines the multiple roles that globalised, branded spaces of hospitality can play in tourists' experiences in destinations. It is argued that previous studies have not considered adequately how such commercial hospitality services and spaces interact with and influence tourists' experiences of places. Drawing on a netnographic analysis of online discussions of McDonald's, this study explores how tourists perceive these hospitality venues, and how they use them to engage with foreign destinations and negotiate the ‘work of tourism’. The data show how tourists (re)construct their identities through reflections on consuming McDonald's. The data also demonstrate that tourists critically evaluate discourses of authenticity and the (in)authenticity of consuming McDonald's. The paper concludes by discussing the implications for the marketing and management of McDonald's and similar branded commercial hospitality venues, the marketing and management of destinations, and it outlines avenues for further research

Genetic Polymorphisms in the Hypothalamic Pathway in Relation to Subsequent Weight Change – The DiOGenes Study

BACKGROUND: Single nucleotide polymorphisms (SNPs) in genes encoding the components involved in the hypothalamic pathway may influence weight gain and dietary factors may modify their effects. AIM: We conducted a case-cohort study to investigate the associations of SNPs in candidate genes with weight change during an average of 6.8 years of follow-up and to examine the potential effect modification by glycemic index (GI) and protein intake. METHODS AND FINDINGS: Participants, aged 20-60 years at baseline, came from five European countries. Cases ('weight gainers') were selected from the total eligible cohort (n = 50,293) as those with the greatest unexplained annual weight gain (n = 5,584). A random subcohort (n = 6,566) was drawn with the intention to obtain an equal number of cases and noncases (n = 5,507). We genotyped 134 SNPs that captured all common genetic variation across the 15 candidate genes; 123 met the quality control criteria. Each SNP was tested for association with the risk of being a 'weight gainer' (logistic regression models) in the case-noncase data and with weight gain (linear regression models) in the random subcohort data. After accounting for multiple testing, none of the SNPs was significantly associated with weight change. Furthermore, we observed no significant effect modification by dietary factors, except for SNP rs7180849 in the neuromedin β gene (NMB). Carriers of the minor allele had a more pronounced weight gain at a higher GI (P = 2 x 10⁻⁷). CONCLUSIONS: We found no evidence of association between SNPs in the studied hypothalamic genes with weight change. The interaction between GI and NMB SNP rs7180849 needs further confirmation

Dynamic Switch of Negative Feedback Regulation in Drosophila Akt–TOR Signaling

Akt represents a nodal point between the Insulin receptor and TOR signaling, and its activation by phosphorylation controls cell proliferation, cell size, and metabolism. The activity of Akt must be carefully balanced, as increased Akt signaling is frequently associated with cancer and as insufficient Akt signaling is linked to metabolic disease and diabetes mellitus. Using a genome-wide RNAi screen in Drosophila cells in culture, and in vivo analyses in the third instar wing imaginal disc, we studied the regulatory circuitries that define dAkt activation. We provide evidence that negative feedback regulation of dAkt occurs during normal Drosophila development in vivo. Whereas in cell culture dAkt is regulated by S6 Kinase (S6K)–dependent negative feedback, this feedback inhibition only plays a minor role in vivo. In contrast, dAkt activation under wild-type conditions is defined by feedback inhibition that depends on TOR Complex 1 (TORC1), but is S6K–independent. This feedback inhibition is switched from TORC1 to S6K only in the context of enhanced TORC1 activity, as triggered by mutations in tsc2. These results illustrate how the Akt–TOR pathway dynamically adapts the routing of negative feedback in response to the activity load of its signaling circuit in vivo

Conceptualizing the sensory dimension of tourist experiences

This paper aims to contribute to the conceptualization of the sensory dimension of tourist experiences by discussing its theoretical underpinnings. A multidisciplinary approach to the human senses shows their importance to the individual’s experience and perception of the surrounding world, recommending the appropriateness of a holistic analysis of sensescapes in tourism. A review of empirical studies conducted under the experiential paradigm of tourism on the five human senses (sight, hearing, smell, taste, and touch) evinces the use of both qualitative and quantitative methodologies, which depends on research purposes, but also the practical implications of findings and data analysis to destination marketing and management. The paper discusses the role of the senses in designing tourist experiences, and identifies important topics regarding the study of the sensory dimension of tourist experiences, considering future research opportunities

RORγt + Treg to Th17 ratios correlate with susceptibility to Giardia infection

Funder: Fundacion Alfonso Martin EscuderoFunder: RCUK | Biotechnology and Biological Sciences Research Council (BBSRC); doi: https://doi.org/10.13039/501100000268Funder: Isaac Newton Trust; doi: https://doi.org/10.13039/501100004815Abstract: Infections with Giardia are among the most common causes of food and water-borne diarrheal disease worldwide. Here, we investigated Th17, Treg and IgA responses, and alterations in gut microbiota in two mouse lines with varying susceptibility to Giardia muris infection. Infected BALB/c mice shed significantly more cysts compared with C57BL/6 mice. Impaired control of infection in BALB/c mice was associated with lower Th17 activity and lower IgA levels compared with C57BL/6 mice. The limited metabolic activity, proliferation and cytokine production of Th17 cells in BALB/c mice was associated with higher proportions of intestinal Foxp3+RORγt+ regulatory T cells and BALB/c mice developed increased RORγt+ Treg:Th17 ratios in response to G. muris infection. Furthermore, G. muris colonization led to a significantly reduced evenness in the gut microbial communities of BALB/c mice. Our data indicate that differential susceptibility to Giardia infections may be related to RORγt+ Treg controlling Th17 activity and that changes in the microbiota composition upon Giardia infection partially depend on the host background

Peas grown in media with elevated plant-available silicon levels have higher activities of chitinase and beta-1,3-glucanase, are less susceptible to a fungal leaf spot pathogen and accumulate more foliar silicon

Pea seedlings grown for 5 weeks in a growing medium amended with potassium silicate fertiliser had significantly greater activities of the enzymes chitinase and β-1,3-glucanase in leaf extracts compared with those grown in coir-based control mix, prior to challenge by a foliar pathogen. Additionally, fewer lesions developed on pea leaves inoculated with the fungal pathogen Mycosphaerella pinodes 5 weeks after growth in the Si-amended mix. Plant-available Si, as monosilicic acid, in the Si-amended mix was more than five times that in the control mix. Peas accumulated nearly twice as much silicon (w/w dried foliage) after 3 weeks growth in an alternative potting mix amended with silicon from rice hull derivatives, as those grown in a conventional perlite/sand medium as control. The monosilicic acid content of the rice hull mix was approximately three times greater than that of the perlite/sand mix. There were no significant differences in dry weights between plants from control and Si-amended mixes. The results suggest associations in pea between available silicon in growth media, accumulation of Si within the plant, early activation of host defences and subsequent resistance to fungal pathogens, with potential for reduction and control of diseases