Characterising the response to gliotoxin exposure in Aspergillus fumigatus ΔgliT and ΔgliZ

The non-ribosomal peptide gliotoxin, is a toxic fungal secondary metabolite produced by the filamentous fungus Aspergillus fumigatus. Previous work has implicated its potent anti-fungal properties and importance as a virulence factor in human infection. Availability of the A. fumigatus genome has allowed for the characterisation of the gliotoxin biosynthetic cluster gli, with previous work illustrating the importance of the thioredoxin reductase gliT in self protection against gliotoxin, regulation of which has been shown to be independent of the transcriptional role of gliZ in regulating the cluster. The work presented here characterises the creation of a double gene deletion strain lacking both gliT and gliZ (ΔgliTΔgliZ) ultimately silencing the gli cluster. Phenotypic characterisation revealed that ΔgliTΔgliZ is more sensitive to gliotoxin challenge when compared with ΔgliZ, yet is more resistant when compared with ΔgliT, highlighting the importance of gliT in protection against gliotoxin, especially when the cluster is still expressed. An anti-oxidant role for gliotoxin is highlighted, with co-addition of gliotoxin and hydrogen peroxide resulting in a reduction in the production of reactive oxygen species in A. fumigatus, when compared with hydrogen peroxide only treated cells. Additionally, proteomic and transcriptomic data indicate gliotoxin exposure dysregulates S-adenosyl-L-methionine biosynthesis with key enzymes of this pathway, i.e., S-adenosyl-L-homocysteinase and cobalmin-independent L-methionine synthase, eliciting significant changes in their respective expression in response to gliotoxin in A. fumigatus an also in Saccharomyces cerevisiae. Using a gene candidate approach, S. cerevisiae Δsod1 and Δyap1 sensitivity to exogenous gliotoxin suggest gliotoxin induces some form of oxidative stress on the cell. Furthermore, low to null levels of glutathione were seen to be advantageous to the S. cerevisiae mutant strain Δgsh1, eliciting resistance to gliotoxin challenge. Similarly, glutathione levels were found to significantly altered in A. fumigatus gliT and gliZ mutant lysates and may be a factor in their respective gliotoxin sensitivity. Overall this work highlights key factors which may contribute to gliotoxin toxicity. Highlighting the importance of gliotoxin biosynthetic genes and the pathways involved in the response to gliotoxin exposure

Gliotoxin effects on fungal growth: Mechanisms and exploitation

Although initially investigated for its antifungal properties, little is actually known about the effect of gliotoxin on Aspergillus fumigatus and other fungi. We have observed that exposure of A. fumigatus to exogenous gliotoxin (14 lg/ml), under gliotoxin-limited growth conditions, results in significant alteration of the expression of 27 proteins (up- and down-regulated >1.9-fold; p < 0.05) including de novo expression of Cu, Zn superoxide dismutase, up-regulated allergen Asp f3 expression and down-regulated catalase and a peroxiredoxin levels. Significantly elevated glutathione GSH levels (p < 0.05), along with concomitant resistance to diamide, were evident in A. fumigatus ∆gliT, lacking gliotoxin oxidoreductase, a gliotoxin self-protection gene. Saccharomyces cerevisiae deletents (∆sod1 and ∆yap1) were hypersensitive to exogenous gliotoxin, while ∆gsh1 was resistant. Significant gliotoxin-mediated (5 µg/ml) growth inhibition (p < 0.001) of Aspergillus nidulans, Aspergillus terreus, Aspergillus niger, Cochliobolus heterostrophus and Neurospora crassa was also observed. Growth of Aspergillus flavus, Fusarium graminearum and Aspergillus oryzae was significantly inhibited (p < 0.001) at gliotoxin (10 lg/ml), indicating differential gliotoxin sensitivity amongst fungi. Re-introduction of gliT into A. fumigatus DgliT, at a different locus (ctsD; AFUA_4G07040, an aspartic protease), with selection on gliotoxin, facilitated deletion of ctsD without use of additional antibiotic selection markers. Absence of ctsD expression was accompanied by restoration of gliT expression, and resistance to gliotoxin. Thus, we propose gliT/gliotoxin as a useful selection marker system for fungal transformation. Finally, we suggest incorporation of gliotoxin sensitivity assays into all future fungal functional genomic studies

Regulation of Nonribosomal Peptide Synthesis: bis-Thiomethylation Attenuates Gliotoxin Biosynthesis in Aspergillus fumigatus

Gliotoxin is a redox-active nonribosomal peptide produced by Aspergillus fumigatus. Like many other disulfide-containing epipolythiodioxopiperazines, a bis-thiomethylated form is also produced. In the case of gliotoxin, bisdethiobis(methylthio)gliotoxin (BmGT) is formed for unknown reasons by a cryptic enzyme. Here, we identify the S-adenosylmethionine- dependent gliotoxin bis-thiomethyltransferase (GtmA), which converts dithiogliotoxin to BmGT. This activity, which is induced by exogenous gliotoxin, is only detectable in protein lysates of A. fumigatus deficient in the gliotoxin oxidoreductase, gliT. Thus, GtmA is capable of substrate bis-thiomethylation. Deletion of gtmA completely abrogates BmGT formation and we now propose that the purpose of BmGT formation is primarily to attenuate gliotoxin biosynthesis. Phylogenetic analysis reveals 124 GtmA homologs within the Ascomycota phylum. GtmA is encoded outside the gliotoxin biosynthetic cluster and primarily serves to negatively regulate gliotoxin biosynthesis. This mechanism of postbiosynthetic regulation of nonribosomal peptide synthesis appears to be quite unusual

A Pilot Study of Sidewalk Equity in Seattle Using Crowdsourced Sidewalk Assessment Data

We examine the potential of using large-scale open crowdsourced sidewalk data from Project Sidewalk to study the distribution and condition of sidewalks in Seattle, WA. While potentially noisier than professionally gathered sidewalk datasets, crowdsourced data enables large, cross-regional studies that would be otherwise expensive and difficult to manage. As an initial case study, we examine spatial patterns of sidewalk quality in Seattle and their relationship to racial diversity, income level, built density, and transit modes. We close with a reflection on our approach, key limitations, and opportunities for future work.Comment: Workshop paper presented at "The 1st ASSETS'22 Workshop on The Future or urban Accessibility (UrbanAccess'22)

Hair coat properties of donkeys, mules and horses in a temperate climate

Background There are clear differences between donkeys and horses in their evolutionary history, physiology, behaviour and husbandry needs. Donkeys are often kept in climates they are not adapted to and as such may suffer impaired welfare unless protection from the elements is provided. Objectives We provide the first direct comparison of the hair coat properties of donkeys, mules and horses living outside, throughout the year, in the temperate climate of the UK. Study Design The weight, length and width of hair were measured, across the four seasons, as indicators of the hair coat insulation properties. Methods Hair samples were taken from 42 animals: 18 donkeys (4 females, 14 males), 16 horses (6 females, 10 males), and eight mules (5 females, 3 males), in March, June, September and December. Results Donkeys’ hair coats do not significantly differ across the seasons. All three measurements of the insulation properties of the hair samples indicate that donkeys do not grow a winter coat and that their hair coat was significantly lighter, shorter and thinner than that of horses and mules in winter. In contrast the hair coats of horses changed significantly between seasons, growing thicker in winter. Main Limitations The measurements cover only a limited range of features that contribute to the thermo-regulation of an animal. Further research is needed to assess shelter preferences by behavioural measures, and absolute heat loss via thermoimaging. Conclusions Donkeys, and to a lesser extent mules, appear not to be as adapted to colder, wet climates as horses, and may therefore require additional protection from the elements, such as access to a wind and waterproof shelter, in order for their welfare needs to be met

Do You Need to Travel? Mapping Face-to-Face Communication Objectives to Technology Affordances

Computer-mediated communications (CMC) can be used as a substitute for face-to-face (FtF) meetings but their effectiveness is highly context dependent. This paper describes a theoretical framework and initial experimental design for characterizing a travel replacement threshold. This effort begins with a use case of remote engineering maintenance training, conducted in three conditions: side-by-side (physically proximate), teleconference (using off-the-shelf software), and a custom VR/AR system designed to provide the apprentice with a virtual view of both the instructor’s larger scale lab and smaller scale workbench. The research hypotheses, experimental protocol, and dependent measures are described. The task involves an instructor demonstrating a circuit board troubleshooting task to a remote apprentice. The apprentice then completes the trained task independently, and performance and subject preferences are compared across conditions. The details of this paper, the result of extensive literature review and winnowing of variables, may assist researchers exploring CMC, training, or social communication

RED experiment: an assessment of boundary layer effects in a trade winds regime on microwave and infrared propagation over the sea, The

Includes bibliographical references (pages 1364-1365).The Rough Evaporation Duct experiment aimed to see if the effects of ocean waves account for errors in modeling the ranges at which radar and infrared can detect low-flying targets

Detrimental Effects of Environmental Tobacco Smoke in Relation to Asthma Severity

Background: Environmental tobacco smoke (ETS) has adverse effects on the health of asthmatics, however the harmful consequences of ETS in relation to asthma severity are unknown. Methods: In a multicenter study of severe asthma, we assessed the impact of ETS exposure on morbidity, health care utilization and lung functions; and activity of systemic superoxide dismutase (SOD), a potential oxidative target of ETS that is negatively associated with asthma severity. Findings: From 2002-2006, 654 asthmatics (non-severe 366, severe 288) were enrolled, among whom 109 non-severe and 67 severe asthmatics were routinely exposed to ETS as ascertained by history and validated by urine cotinine levels. ETS-exposure was associated with lower quality of life scores; greater rescue inhaler use; lower lung function; greater bronchodilator responsiveness; and greater risk for emergency room visits, hospitalization and intensive care unit admission. ETS-exposure was associated with lower levels of serum SOD activity, particularly in asthmatic women of African heritage. Interpretation: ETS-exposure of asthmatic individuals is associated with worse lung function, higher acuity of exacerbations, more health care utilization, and greater bronchial hyperreactivity. The association of diminished systemic SOD activity to ETS exposure provides for the first time a specific oxidant mechanism by which ETS may adversely affect patients with asthma. © 2011 Comhair et al

EPOCHS Paper II: The Ultraviolet Luminosity Function from 7.5<z<13.57.5<z<13.5 using 110 square arcminutes of deep, blank-field data from the PEARLS Survey and Public Science Programmes

We present an analysis of the ultraviolet luminosity function (UV LF) and star formation rate density of distant galaxies ($7.5 < z < 13.5$) in the `blank' fields of the Prime Extragalactic Areas for Reionization Science (PEARLS) survey combined with Early Release Science (ERS) data from the CEERS, GLASS and NGDEEP surveys/fields. We use a combination of SED fitting tools and quality cuts to obtain a reliable selection and characterisation of high-redshift ($z>6.5$) galaxies from a consistently processed set of deep, near-infrared imaging. Within an area of 110 arcmin$^{2}$, we identify 214 candidate galaxies at redshifts $z>6.5$ and we use this sample to study the ultraviolet luminosity function (UV LF) in four redshift bins between $7.5<z<13.5$. The measured number density of galaxies at $z=8$ and $z=9$ match those of past observations undertaken by the em Hubble Space Telescope (HST). However, towards higher redshifts we find that the evolution of the UV LF is mild, resulting in higher measured number densities of UV luminous galaxies at $z=10.5$ and $z=12.5$ compared to predictions from simulations and past HST observations. When examining the star formation rate density of galaxies at this time period, our observations are still consistent with a constant star formation efficiency, are slightly lower than previous early estimations using JWST and support galaxy driven reionization at $z\sim8$.Comment: 28 Pages, 4 Tables, 9 Figures, Submitted to Ap