bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of greater competitive ability in countering age disadvantages in larval competition inDrosophila melanogaster
Authors: Venkitachalam Srikant , Deep Auroni , Das Srijan , Joshi Amitabh
Published: July 2023

Background

Populations ofDrosophila melanogasteradapted to high larval densities evolve increased larval competitive ability compared to low density controls. However, traits contributing to greater competitive ability can differ across such populations, depending on the exact details of high-density conditions imposed. In the current study, we consider three sets ofD. melanogasterpopulations adapted to three different kinds of high-density scenarios. These population sets have evolved different degrees of increases in egg size and decreases in egg hatching time as correlates of increased larval competitive ability.

Question

We asked two related questions:

Do populations adapted to larval crowding counter an imposed initial age disadvantage in larval competition, better than their controls?

Do differences in egg size and egg hatching time among crowding-adapted populations matter in competitive performance when suffering age disadvantage?

Study system

We used three sets of outbred laboratoryDrosophila melanogasterpopulations selected for larval crowding with different egg number, food volume and vial type combinations (named MCU, CCU and LCU). We also used one set of low-density ancestral control populations (named MB).

Methods

We implemented high density cultures with half the eggs from one of the study (focal) populations, and the other half from a common marked competitor population (Orange Eye: OE). We provided head start durations of 0, 3, 5, or 7 hours to the eggs of the common competitor. This imposed the respective age disadvantage to the larvae of the focal population. Pre-adult development time of survivors was the indicator of competitive performance used.

Results

All crowding-adapted populations countered an initial age disadvantage better than the control populations. We did not see any differences among crowding adapted populations regarding their performance in countering the age disadvantage. The common competitors showed the best competitive performance against the populations with the greatest egg size and shortest hatching time.

Conclusions

Adaptation to crowding leads to significantly better chances against age disadvantages in larval competition. Temporal head starts need not be of overwhelming advantage in larval competition against superior competitors inDrosophila. Among crowding adapted populations, evolving greater egg size and shorter hatching time does not seem to better offset the effects of age disadvantage to larvae. Differences in larval effectiveness and tolerance of the populations are likely to explain these results.
Pathogenic CANVAS (AAGGG)nrepeats stall DNA replication due to the formation of alternative DNA structures
Authors: Hisey Julia A. , Radchenko Elina A. , Ceschi Silvia , Rastokina Anastasia , Mandel Nicholas H. , McGinty Ryan J. , Matos-Rodrigues Gabriel , Hernandez Alfredo , Nussenzweig André , Mirkin Sergei M.
Published: July 2023

CANVAS is a recently characterized repeat expansion disease, most commonly caused by homozygous expansions of an intronic (A2G3)nrepeat in theRFC1gene. There are a multitude of repeat motifs found in the human population at this locus, some of which are pathogenic and others benign. In this study, we conducted structure-functional analyses of the main pathogenic (A2G3)nand the main nonpathogenic (A4G)nrepeats. We found that the pathogenic, but not the nonpathogenic, repeat presents a potent, orientation-dependent impediment to DNA polymerizationin vitro. The pattern of the polymerization blockage is consistent with triplex or quadruplex formation in the presence of magnesium or potassium ions, respectively. Chemical probing of both repeats in supercoiled DNA reveals triplex H-DNA formation by the pathogenic repeat. Consistently, bioinformatic analysis of the S1-END-seq data from human cell lines shows preferential H-DNA formation genome-wide by (A2G3)nmotifs over (A4G)nmotifsin vivo. Finally, the pathogenic, but not the non-pathogenic, repeat stalls replication fork progression in yeast and human cells. We hypothesize that CANVAS-causing (A2G3)nrepeat represents a challenge to genome stability by folding into alternative DNA structures that stall DNA replication.
First report of geophagy by chimpanzees in Comoé National Park, Ivory Coast
Authors: Lapuente Juan , Linsenmair K. Eduard
Published: July 2023

West African chimpanzees (Pan troglodytes verus) are critically endangered, therefore knowing their ecological needs is necessary to implement proper conservation measures, especially in the face of climatic change. We report here the consumption of soil by wild chimpanzees living in Comoé National Park, Ivory Coast. We confirmed through camera-trap recording that chimpanzees of all ages and both sexes consumed it for several years at least in one community and more occasionally in a second one, aided by leaf-sponge tools. Our results suggest that these chimpanzees living in a savanna-forest mosaic may need minerals supplement, including sodium or/and clay to aid digestion, mainly during the dry season.
Genes associated with fitness and disease severity in the pan-genome of mastitis-associatedEscherichia coli
Authors: Olson Michael A. , Cullimore Caz , Hutchison Weston D. , Grimsrud Aleksander , Nobrega Diego , Buck Jeroen De , Barkema Herman W. , Wilson Eric , Pickett Brett E. , Erickson David L.
Published: July 2023

Bovine mastitis caused byEscherichia colimay manifest as subclinical through severe acute disease and can be transient or persistent in nature. Little is known about bacterial factors that impact clinical outcomes or allow some strains to outcompete others in the mammary gland (MG) environment. Mastitis-associatedE. coli(MAEC) may have distinctive characteristics which may contribute to the varied nature of the disease. In this study, we sequenced the genomes of 96 MAEC strains isolated from cattle with clinical mastitis (CM). We utilized clinical severity data to perform genome-wide association studies to identify accessory genes associated with strains isolated from mild or severe CM, or with high or low competitive fitness duringin vivocompetition assays. Genes associated with pathogenic or commensal strains isolated from bovine and avian sources were also identified. A type-2 secretion system (T2SS) and a chitinase (ChiA) exported by this system were strongly associated with pathogenic isolates compared with commensal strains. Strains carrying these genes also had higher competitive fitness during experimental intramammary infections. Deletion ofchiAfrom MAEC isolates decreased their adherence to cultured bovine mammary epithelial cells, suggesting that the increased fitness associated with strains possessing this gene may be due to better attachment in the MG.

Importance

Bovine mastitis caused by MAEC compromises animal health and inflicts substantial product losses in dairy farming. Given their high levels of intraspecies genetic variability, virulence factors of commonly used MAEC model strains may not be relevant to all members of this group. Here we analyzed clinical data as well as fitness (quantified in a mouse MG model) of diverse MAEC isolates to identify accessory genes that contribute to infection. We demonstrated a novel role for chitinase in promoting attachment to mammary epithelial cells. Reverse genetic approaches can be applied to the collection of strains and their complete genome sequences that we have presented here. Overall, these results provide a much richer understanding of MAEC and suggest bacterial processes that may underlie the clinical diversity associated with mastitis and their adaptation to this unique environment.
Genome assembly reconstruction of the Japanese honey bee,Apis cerana japonica(Hymenoptera: Apidae), using homology-based assembly and nanopore long-reads
Authors: Masuoka Yudai , Jouraku Akiya , Kuwazaki Seigo , Yoshiyama Mikio , Horigane-Ogihara Mari , Maeda Taro , Suzuki Yutaka , Bono Hidemasa , Kimura Kiyoshi , Yokoi Kakeru
Published: July 2023

Honey bees are important for agriculture (e.g., pollination and honey production). Additionally, honey bees are an important insect model species, especially as model social insects. The Japanese honey bee,Apis cerana japonica(a subspecies of the Asian honey bee,Apis cerana), is a Japanese domestic honey bee, which has several subspecies-specific traits. We previously constructed the draft genome sequence data ofA. cerana japonica, but it needed to be improved considering the use of the genome sequence data for genome structural analysis and repetitive region analysis, as well as the availability of chromosome-level genome data ofA. melliferaandA. cerana. In this study, we constructed the improvedA. cerana japonicagenome data and new gene set data with functional annotations. The constructed genome data, including 16 pseudochromosomes, was found to be highly contiguous and complete, and the gene set data covered most of the core genes in the BUSCO database. Thus, the constructed genome and gene set data have become more suitable as the reference data ofA. cerana japonica.
The Feather Epithelium Contributes to the Dissemination and Ecology of clade 2.3.4.4b H5 High Pathogenicity Avian Influenza Virus in Ducks
Authors: Gaide Nicolas , Filaire Fabien , Bertran Kateri , Crispo Manuela , Dirat Malorie , Secula Aurélie , Foret-Lucas Charlotte , Payré Bruno , Perlas Albert , Cantero Guillermo , Majó Natàlia , Soubies Sébastien , Guérin Jean-Luc
Published: July 2023

Immature feathers are known replication sites for high pathogenicity avian influenza viruses (HPAIVs) in poultry. However, it is unclear whether feathers play an active role in viral transmission. This study aims to investigate the contribution of the feather epithelium to the dissemination of clade 2.3.4.4b goose/Guangdong/1996 lineage H5 HPAIVs in the environment, based on natural and experimental infections of domestic ducks. During the 2016-22 outbreaks, H5 HPAIVs exhibited persistent and marked feather epitheliotropism in naturally infected commercial ducks. Infection of feathers resulted in epithelial necrosis, disruption, and the production and release of infectious virions. Viral and feather antigens colocalized in dust samples obtained from poultry barns housing naturally infected birds. In summary, the feather epithelium contributes to viral replication, and it is a likely source of environmental infectious material. This underestimated excretion route could greatly impact the ecology of HPAIVs, facilitating airborne and preening-related infections within a flock, and promoting prolonged viral infectivity and long-distance viral transmission between poultry farms.

Abstract Figure
Bile-induced biofilm formation inBacteroides thetaiotaomicronrequires magnesium efflux by an RND pump
Authors: Lopes Anne-Aurélie , Deschamps Julien , Georgeault Sonia , Cokelaer Thomas , Briandet Romain , Ghigo Jean-Marc
Published: July 2023

Bacteroides thetaiotaomicronis a prominent member of the human gut microbiota contributing to nutrient exchange, gut function, and maturation of the host’s immune system. This obligate anaerobe symbiont can adopt a biofilm lifestyle and it was recently shown thatB. thetaiotaomicronbiofilm formation is promoted by the presence of bile, a process also requiring aB. thetaiotaomicronextracellular DNase, which is not, however, regulated by bile. Here we showed that bile induces the expression of several Resistance-Nodulation-Division (RND) efflux pumps and that inhibiting their activity with a global competitive efflux inhibitor impaired bile-dependent biofilm formation. We then showed that, among the bile-induced RND-efflux pumps, only the tripartite BT3337-BT3338-BT3339 pump, re-named BipABC (for Bile Induced Pump A (BT3337), B (BT3338) and C (BT3339), is required for biofilm formation. We demonstrated that BipABC is involved in the efflux of magnesium to the biofilm extracellular matrix, which leads to a decrease of eDNA concentration. The release of magnesium in the biofilm matrix also impacts biofilm structure, potentially by modifying the electrostatic repulsion forces within the matrix, reducing interbacterial distance and allowing bacteria to interact more closely and form denser biofilms. Our study therefore identifies a new molecular determinant ofB. thetaiotaomicronbiofilm formation in response to bile salts and provides a better understanding on how an intestinal chemical cue regulates biofilm formation in a major gut symbiont.

IMPORTANCE

Bacteroides thetaiotaomicronis a prominent member of the human gut microbiota able to degrade dietary and host polysaccharides, altogether contributing to nutrient exchange, gut function, and maturation of the host’s immune system. This obligate anaerobe symbiont can adopt a biofilm community lifestyle, providing protection against environmental factors that might, in turn, protect the host from dysbiosis and dysbiosis-related diseases. It was recently shown thatB. thetaiotaomicronexposure to intestinal bile promotes biofilm formation. Here we reveal that a specificB. thetaiotaomicronmembrane efflux pump is induced in response to bile, leading to the release of magnesium ions, potentially reducing electrostatic repulsion forces between components of the biofilm matrix. This leads to a reduction of interbacterial distance and strengthens the biofilm structure. Our study therefore provides a better understanding of how bile promotes biofilm formation in a major gut symbiont, potentially promoting microbiota resilience to stress and dysbiosis events.
Phages prevent biofilm formation on catheters under flow
Authors: Bseikri Hoda , Michniewski Slawomir , Serrano Eduardo Goicoechea , Jameson Eleanor
Published: July 2023

Biofilms pose a significant challenge in medical settings, leading to persistent infections. Phage therapy has shown promise in biofilm eradication, but its effectiveness under dynamic flow conditions remains unclear. Here we use two novel phages isolated onKlebsiella, Llofrudd and Samara, and characterized their genomes, host range and virulence. In this study, we built a simple catheterised bladder model with flow to investigate the impact of phage treatment on biofilm viability in a flow-based catheter model. Our analyses demonstrate that phages Llofrudd and Samara are the same species and infect a limited number of strains (3/222), but across three species:Klebsiella aerogenes, Klebsiella pneumoniaeandE. coli. Phage treatment significantly reducedE. colibiofilm viability in catheters both in static conditions and under flow, highlighting the potential of phage therapy as an intervention strategy for catheter associated urinary tract infections (CAUTI).
The influence of polarized membrane ion carriers and extracellular electrical/pH gradients on cell ionic homeostasis and locomotion
Authors: Li Yizeng , Sun Sean X.
Published: July 2023

Anisotropic environmental signals or polarized membrane ion/solute carriers can generate spatially-varying intracellular gradients, leading to polarized cell dynamics. For example, directional migration of neutrophils, galvanotaxis of glioblastoma, and water flux in kidney cells, all result from the polarized distribution of membrane ion carriers and other intracellular components. The underlying physical mechanisms behind how polarized ion carriers interact with environmental signals are not well studied. Here, we use a physiologically-relevant, physics-based mathematical model to reveal how ion carriers generate intracellular ionic and voltage gradients. The model is able to discern the contribution of individual ion carriers to the intracellular pH gradient, electric potential, and water flux. We discover that an extracellular pH gradient leads to an intracellular pH gradient via chloride-bicarbonate exchangers, whereas an extracellular electric field leads to an intracellular electric potential gradient via passive potassium channels. In addition, the mechanical-biochemical coupling can modulate actin distribution and flow, and create biphasic dependence of the cell speed on water flux. Moreover, we find that F-actin interaction with NHE alone can generate cell movement, even when other ion carriers are not polarized. Taken together, the model shows the importance of cell ion dynamics in modulating cell migration and cytoskeletal dynamics.
Disparate requirements for RAD54L in replication fork reversal
Authors: Uhrig Mollie E. , Sharma Neelam , Maxwell Petey , Selemenakis Platon , Mazin Alexander V. , Wiese Claudia
Published: July 2023

RAD54L is a DNA motor protein with multiple roles in homologous recombination DNA repair (HR).In vitro, RAD54L was shown to also catalyze the reversal and restoration of model replication forks. In cells, however, little is known about how RAD54L may regulate the dynamics of DNA replication. Here, we show that RAD54L restrains the progression of replication forks and functions as a fork remodeler in human cells. Analogous to HLTF, SMARCAL1, and FBH1, and consistent with a role in fork reversal, RAD54L decelerates fork progression in response to replication stress and suppresses the formation of replication-associated ssDNA gaps. Interestingly, loss of RAD54L prevents nascent strand DNA degradation in both BRCA1/2- and 53BP1-deficient cells, suggesting that RAD54L functions in both pathways of RAD51-mediated replication fork reversal. In the HLTF/SMARCAL1 pathway, RAD54L is critical, but its ability to catalyze branch migration is dispensable, indicative of its function downstream of HLTF/SMARCAL1. Conversely, in the FBH1 pathway, branch migration activity of RAD54L is essential, and FBH1 engagement is dependent on its concerted action with RAD54L. Collectively, our results reveal disparate requirements for RAD54L in two distinct RAD51-mediated fork reversal pathways, positing its potential as a future therapeutic target.
Activation of ATF3 via the Integrated Stress Response Pathway Regulates Innate Immune Response to Restrict Zika Virus
Authors: Badu Pheonah , Baniulyte Gabriele , Sammons Morgan A. , Pager Cara T.
Published: July 2023

Zika virus (ZIKV) is a re-emerging mosquito-borne flavivirus that can have devastating health consequences. The developmental and neurological effects from a ZIKV infection arise in part from the virus triggering cellular stress pathways and perturbing transcriptional programs. To date, the underlying mechanisms of transcriptional control directing viral restriction and virus-host interaction are understudied. Activating Transcription Factor 3 (ATF3) is a stress-induced transcriptional effector that modulates the expression of genes involved in a myriad of cellular processes, including inflammation and antiviral responses, to restore cellular homeostasis. While ATF3 is known to be upregulated during ZIKV infection, the mode by which ATF3 is activated and the specific role of ATF3 during ZIKV infection is unknown. In this study, we show via inhibitor and RNA interference approaches that ZIKV infection initiates the integrated stress response pathway to activate ATF4 which in turn induces ATF3 expression. Additionally, by using CRISPR-Cas9 system to delete ATF3, we found that ATF3 acts to limit ZIKV gene expression in A549 cells. We also determined that ATF3 enhances the expression of antiviral genes such as STAT1 and other components in the innate immunity pathway to induce an ATF3-dependent anti-ZIKV response. Our study reveals crosstalk between the integrated stress response and innate immune response pathways and highlights an important role for ATF3 in establishing an antiviral effect during ZIKV infection.

Importance

ZIKV is a re-emerging mosquito-borne flavivirus that co-opts cellular mechanisms to support viral processes which can reprogram the host transcriptional profile. Such viral-directed transcriptional changes and the pro- or anti-viral outcomes remain understudied. We previously showed that ATF3, a stress-induced transcription factor, is significantly upregulated in ZIKV infected mammalian cells, along with other cellular and immune response genes. We now define the intracellular pathway responsible for ATF3 activation and elucidate the impact of ATF3 expression on ZIKV infection. We show that during ZIKV infection the integrated stress response pathway stimulates ATF3 which enhances the innate immune response to antagonize ZIKV infection. This study establishes a link between viral-induced stress response and transcriptional regulation of host defense pathways and thus expands our knowledge on virus-mediated transcriptional mechanisms and transcriptional control of interferon stimulated genes during ZIKV infection.
Electrobiocorrosion by Microbes without Outer-Surface Cytochromes
Authors: Holmes Dawn E. , Woodard Trevor L. , Smith Jessica A. , Musat Florin , Lovley Derek R.
Published: July 2023

Anaerobic microbial corrosion of iron-containing metals causes extensive economic damage. Some microbes are capable of direct metal-to-microbe electron transfer (electrobiocorrosion), but the prevalence of electrobiocorrosion among diverse methanogens and acetogens is poorly understood because of a lack of tools for their genetic manipulation. Previous studies have suggested that respiration with 316L stainless steel as the electron donor is indicative of electrobiocorrosion because, unlike pure Fe0, 316L stainless steel does not abiotically generate H2as an intermediary electron carrier. Here we report that all of the methanogens (Methanosarcina vacuolata,Methanothrix soehngenii, andMethanobacteriumstrain IM1) and acetogens (Sporomusa ovata,Clostridium ljungdahlii) evaluated respired with pure Fe0as the electron donor, but onlyM. vacuolata,Mx soehngenii, andS. ovatawere capable of stainless steel electrobiocorrosion. The electrobiocorrosive methanogens required acetate as an additional energy source in order to produce methane from stainless steel. Co-cultures ofS. ovataandMx. soehngeniidemonstrated how acetogens can provide acetate to methanogens during corrosion. Not only wasMethanobacteriumstrain IM1 not capable of electrobiocorrosion, but it also did not accept electrons fromGeobacter metallireducens, an effective electron- donating partner for direct interspecies electron transfer to all methanogens that can directly accept electrons from Fe0. The finding thatM. vacuolata,Mx. soehngenii, andS. ovataare capable of electrobiocorrosion, despite a lack of the outer-surfacec-type cytochromes previously found to be important in other electrobiocorrosive microbes, demonstrates that there are multiple microbial strategies for making electrical contact with Fe0.

Impact Statement

Understanding how anaerobic microbes receive electrons from Fe0is likely to lead to novel strategies for mitigating the corrosion of iron-containing metals, which has an enormous economic impact. Electrobiocorrosion, is a relatively recently recognized corrosion mechanism. It was previously demonstrated in pure cultures when Fe0oxidation was inhibited by deletion of genes for outer-surfacec-type cytochromes known to be involved in other forms of extracellular electron exchange. However, many methanogens and acetogens lack obvious outer-surface electrical connections and are difficult to genetically manipulate. The study reported here provides an alternative approach to evaluating whether microbes are capable of electrobiocorrosion that does not require genetic manipulation. The results indicate thatMethanobacteriumstrain IM1, is not electrobiocorrosive, in contrast to previous speculation. However, some methanogens and acetogens without known outer-surfacec-type cytochromes do appear to be capable of electrobiocorrosion, suggesting that this corrosion mechanism may be more widespread than previously thought.
The capsular polysaccharide obstructs wall teichoic acid functions inStaphylococcus aureus
Authors: Lehmann Esther , van Dalen Rob , Gritsch Lisa , Slavetinsky Christoph , Korn Natalya , Rohmer Carina , Krause Daniela , Peschel Andreas , Weidenmaier Christopher , Wolz Christiane
Published: July 2023

Background

The cell envelope ofStaphylococcus aureuscontains two major secondary cell wall glycopolymers: capsular polysaccharide (CP) and wall teichoic acid (WTA). Both the CP and the WTA are attached to the cell wall and play distinct roles inS. aureuscolonization, pathogenesis, and bacterial evasion of host immune defenses.

Objective

We aimed to investigate whether CP interferes with WTA-mediated properties.

Methods

Strains with natural heterogeneous expression of CP, strains with homogeneous high CP expression and CP-deficient strains were compared to WTA deficient controls regarding WTA dependent phage binding, cell adhesion, IgG deposition, and virulencein vivo.

Results

WTA-mediated phage adsorption, specific antibody deposition and cell adhesion were negatively correlated with CP expression. WTA, but not CP, enhanced the bacterial burden in a mouse abscess model, while CP overexpression resulted in intermediate virulencein vivo.

Conclusions

CP protects the bacteria from WTA-dependent opsonization and phage binding. This protection comes at the cost of diminished adhesion to host cells. The highly complex regulation and mostly heterogeneous expression of CP has probably evolved to ensure the survival and optimal physiological adaptation of the bacterial population as a whole.
Seed tuber imprinting shapes the next-generation potato microbiome
Authors: Song Yang , Spooren Jelle , Jongekrijg Casper D. , Manders Ellen H.H. , de Jonge Ronnie , Pieterse Corné M.J. , Bakker Peter A.H.M. , Berendsen Roeland L.
Published: July 2023

Potato seed tubers are colonized and inhabited by soil-borne microbes, some of which can positively or negatively impact the performance of the emerging daughter plant in the next season. In this study, we investigated the intergenerational inheritance of microbiota from seed tubers to next-season daughter plants by amplicon sequencing of bacterial and fungal microbiota associated with tubers and roots of two seed potato genotypes produced in six different fields. We observed that field of production and potato genotype significantly affected the seed tuber microbiome composition and that these differences persisted during winter storage of the seed tubers. When seed tubers from different production fields were planted in a single trial field, the microbiomes of daughter tubers and roots of the emerging plants could still be distinguished according to the field of origin of the seed tuber. Remarkably, we found little evidence of direct vertical inheritance of field-unique microbes from the seed tuber to the daughter tubers or roots. Hence, we hypothesize that this intergenerational “memory” is imprinted in the seed tuber, resulting in differential microbiome assembly strategies depending on the field of production of the seed tuber.
Cryo-EM structure of cell-free synthesized human histamine H2receptor coupled to heterotrimeric Gsprotein in lipid nanodisc environment
Authors: Köck Zoe , Schnelle Kilian , Persechino Margherita , Umbach Simon , Schihada Hannes , Januliene Dovile , Parey Kristian , Pockes Steffen , Kolb Peter , Dötsch Volker , Möller Arne , Hilger Daniel , Bernhard Frank
Published: July 2023

Here we describe the cryo-electron microscopy structure of the human histamine 2 receptor (H2R) in an active conformation with bound histamine and in complex with Gsheterotrimeric protein at an overall resolution of 3.4 Å. The complex was generated by cotranslational insertion into preformed nanodisc membranes using cell-free synthesis inE. colilysates. It is the first structure obtained by this detergent-free strategy and the first GPCR/Gscomplex structure in lipid environment. Structural comparison with the inactive conformation of H2R and the inactive and Gq-coupled active state of H1R together with structure-guided functional experiments reveal molecular insights into the specificity of ligand binding and G protein coupling for this receptor family. We demonstrate lipid-modulated folding of cell-free synthesized H2R, its agonist-dependent internalization and its interaction with endogenously synthesized H1R and H2R in HEK293 cells by applying a recently developed nanotransfer technique.
Influence of technological synthesis conditions on corrosion behaviour and mechanical properties for NiTi alloys
Authors: Tunçay Badegül , Çuğ Harun , Tunçay Tansel , Özyürek Dursun , Cesarz-Andraczke Katarzyna
Published: July 2023

Purpose

This study aims to investigate NiTi alloys’ characterization and corrosion behaviour produced by two different powder metallurgy (PM) methods.

Design/methodology/approach

It was pre-formed under a protective atmosphere at 900 °C under a force of 45 MPa and sintered for 1 h under 10–6 Mbar in an atmosphere-controlled heat treatment furnace at 1,100 °C. The relationship between microstructural properties, SEM, XRD, density, microhardness and corrosion behaviour of pre-alloyed NiTi alloys produced by two different methods with the production method was investigated.

Findings

As a result of the studies, TiO, NiTi, NiTi2 and Ni3Ti intermetallics were determined in XRD examinations. The best surface roughness was observed in the mechanically milled (MM’ed) pre-alloyed NiTi alloy compared to the pre-alloyed NiTi alloy mixed with turbula. The corrosion tests performed in 3.5% NaCl solution determined that the MM’ed pre-alloyed NiTi alloy had better corrosion resistance than the pre-alloyed NiTi alloy mixed with turbula. Pitting corrosion was visualized in the SEM images taken from the corrosion surfaces.

Originality/value

Two different PM methods produced pre-alloyed NiTi powders, and the effects of these methods on the mechanical and corrosion resistance of NiTi alloys were systematically investigated for the first time.
System and content factors associated with college students’ adoption of YouTube for learning purposes
Authors: Harper Lindsey M. , James Elizabeth D. , Joo Soohyung , Kim Youngseek
Published: July 2023

Purpose

Today’s undergraduate students have spent a significant portion of their lives using YouTube for various reasons, whether for entertainment, personal development or academic learning purposes. This study aims to investigate how system factors (i.e. reliability, usability and searchability), interaction factors (i.e. provider and user interactions) and content factors (i.e. format, relevance and coverage) affect undergraduate students’ satisfaction with YouTube and their intentions to adopt YouTube for learning purposes.

Design/methodology/approach

This research uses the information systems success model as its theoretical framework to explore the system, interaction and content factors associated with undergraduate students’ satisfaction with YouTube and their intentions to use YouTube for learning. The proposed hypotheses were examined by the structural equation modelling technique based on a survey with 345 undergraduate students at a Southeastern institution in the USA.

Findings

The results indicate that both system factors (including reliability, usability and searchability) and content factors (including format, relevance and coverage) have a statistically significant effect on students’ satisfaction with YouTube. This study also demonstrates that students’ satisfaction with YouTube significantly influences their intentions to use the platform for learning purposes.

Research limitations/implications

The proposed research model provides a novel perspective in understanding the complex nature of students’ adoption of YouTube for learning purposes, led by both system and content factors mediated by satisfaction with YouTube.

Practical implications

This study suggests that when YouTube is intuitive to use and relevant content is added to the platform regularly, students are more likely to adopt this platform for learning purposes. As a result, it is critical that librarians remain aware of information-seeking practices and platforms used by students to tailor approaches to teaching information literacy to help students understand how to use the platform effectively.

Originality/value

Using the information systems success model, this research sheds light on the roles of system and content factors in undergraduate students’ satisfaction with YouTube and their intentions to use it for learning.
Tokenism in the workplace: does brand activism benefit LGBTQ+ employees in the hospitality industry?
Authors: Bogicevic Vanja , Li Yizhi , Salvato Edward D.
Published: July 2023

Purpose

Hospitality firms adopted diverse hiring policies and public declarations of support for LGBTQ+ causes through brand activism. The impact of activism on LGBTQ+ employees’ workplace experiences has been ambiguous. This study aims to examine the hospitality and tourism employees’ perceptions of gay and lesbian leaders as token-hires among hospitality employees and the spillover effect on company’s motives for hiring the leaders. This study further explores LGBTQ+ employees’ reactions to token-hiring as a form of activism, and how workplace interactions as passing/revealing LGBTQ+ individuals shaped their career development.

Design/methodology/approach

This research adopted a sequential mixed-methods design. An experiment examines how employees judge gay vs lesbian hospitality leaders as token hires, contingent on their own gender identity. It further tests the conditional mediation of tokenism on company’s egoistic motives for activism. A qualitative study explores the reactions to token-hiring as activism from the perspective of LGBTQ+ leaders who reflect on their own careers and workplace experiences.

Findings

Tokenism in the hospitality workplace is recognized as the phenomenon attributed to groups at the intersection of identities (e.g. gay men). Findings demonstrate the spillover effect of tokenism perceptions of gay male leaders by other men on company’s egoistic motives for activism. This effect is not observed for a lesbian female leader. Results from interviews suggest that hospitality and tourism LGBTQ+ employees predominantly take the post-gay vs political approach when managing their sexual identities at work and feel ambivalent toward token-hiring as LGBTQ+ brand activism.

Originality/value

This research contributes to understanding workplace challenges of LGBTQ+ employees and how they are perceived by others contingent on gender identity. It also explores the role of tokenism in their experiences.
Corporate entrepreneurship in a collectivist culture: the role of time availability
Authors: Janićijević Nebojša , Kontić Ljiljana
Published: July 2023

Purpose

This study aims to investigate whether the model containing five organisational determinants of corporate entrepreneurship developed by Kuratko, Hornsby and Covin is valid in Serbia.

Design/methodology/approach

The model was tested on a sample that included managers and employees from four banks in Serbia. The Corporate Entrepreneurship Assessment Instrument (CEAI) was used as the research instrument and factor analysis was used as the basic statistical method. This study examined whether the 48 items that compose the CEAI could be grouped in the context of the national culture of Serbia to provide the five determinants that were identified by Kuratko, Hornsby and Covin.

Findings

The results show that the factor analysis identified four determinants identical to those in the CEAI model. However, time availability failed the validity test in previous studies conducted in Serbia and other countries with collectivist cultures. It can be concluded that collectivism connected with high-power distance, uncertainty avoidance and the polychromatic concept of time caused the cultural limitation of time availability as a determinant of corporate entrepreneurship.

Originality/value

This study indicates that national culture could be a factor that determines the validity of organisational determinants of corporate entrepreneurship and that these factors cannot be taken for granted in cultures other than those in which the theory of corporate entrepreneurship arose. Finally, corporate entrepreneurship has been investigated in the banking industry, which is unusual because it is globally renowned for its conservatism.
Mainstream economics’ war with the environment: counter-critiques from heterodox economics and Islamic economics
Authors: Yilmaz Ekrem , Deymencioğlu Güler , Atas Mehmet , Sensoy Fatma
Published: July 2023

Purpose

This study aims to present the perspectives of heterodox economics and Islamic economics on environmental economics, as an alternative to mainstream economics, which takes economic growth as its main objective and argues that environmental problems will largely disappear when economic growth is achieved.

Design/methodology/approach

In this study, there was no intention to conduct a detailed analysis of heterodox economic models and Islamic economics. Instead, the approaches to the “environment,” which can be considered as an urgent need of the planet, were evaluated, and the inadequate proposals of the mainstream economics’ environmental approach were theoretically criticized and heterodox economics and Islamic economics were proposed as an alternative model.

Findings

Heterodox and Islamic economics offer alternative models of development prioritizing social and ecological justice to address environmental problems, which is in contrast to mainstream economics’ narrow focus on market mechanisms and individual rationality. Thus, engaging in more dialogue in the context of the environment is inevitable for both schools, considering the vast geography inhabited by Muslims and the proposed heterodox economic policies, and moreover, these approaches are modeled for the first time.

Originality/value

This article presents a synthesis of Islamic economics and heterodox thinking in contrast to mainstream economic policy, highlighting their similarities and differences and providing a more comprehensive understanding of the complexities and potential solutions of environmental problems. To the best of the authors’ knowledge, this approach has not been previously explored, making it an original contribution to the literature.
From supply chain learning to the learning supply chain: drivers, processes, complexity, trade-offs and challenges
Authors: Silvestre Bruno S. , Gong Yu , Bessant John , Blome Constantin
Published: July 2023

Purpose

The view that supply chain learning (SCL) has become a fundamental capability that supply chains must employ to innovate and improve their financial, technological, operational, environmental and social performance is widely accepted. However, the SCL phenomenon is still understudied and not fully understood by scholars, decision-makers and government representatives. This article aims to make sense of the existing literature and to identify important research directions that require further attention.

Design/methodology/approach

This article reviews the diversity of SCL in the literature, proposes a typology of such a phenomenon, provides an overview of key articles in the literature and identifies a series of recommendations for the future development of the field.

Findings

This article combines two fundamental dimensions from the literature (i.e. SCL driver and SCL network) to produce a typology of four types of SCL: Captive, Consortium, Selective and Distributed.

Practical implications

The typology proposed here offers an important framework for supply chain decision-makers to rely on when implementing SCL initiatives. The implications of each type of SCL offer a robust rationale for decision-makers to adopt the most appropriate type of SCL or combinations of SCL types, given each situation. In addition, the typology supports policy-makers in further understanding the SCL phenomenon and creating effective innovation, economic development and sustainability policies through supply chains.

Originality/value

This article offers a novel typology that the authors hope will help scholars to advance the field of SCL in order to understand this important phenomenon. There is no good/bad/better/worse SCL type in the proposed typology, but the critical element for the success of SCL efforts is the level of fit between the type of SCL, the type of knowledge to be created and diffused, and the outcome supply chains aim to achieve with that learning effort. In addition, the authors coin the construct of “the learning supply chain”, which refers to a supply chain that learns constantly by employing all four types of SCL simultaneously.
Assessing place experiences in Luton and Darlington on Twitter with topic modelling and AI-generated lexicons
Authors: Taecharungroj Viriya , Stoica Ioana S.
Published: July 2023

Purpose

The purpose of this paper is to examine and compare the in situ place experiences of people in Luton and Darlington.

Design/methodology/approach

The study used 109,998 geotagged tweets from Luton and Darlington between 2020 and 2022 and conducted topic modelling using latent Dirichlet allocation. Lexicons were created using GPT-4 to evaluate the eight dimensions of place experience for each topic.

Findings

The study found that Darlington had higher counts in the sensorial, behavioural, designed and mundane dimensions of place experience than Luton. Conversely, Luton had a higher prevalence of the affective and intellectual dimensions, attributed to political and faith-related tweets.

Originality/value

The study introduces a novel approach that uses AI-generated lexicons for place experience. These lexicons cover four facets, two intentions and two intensities of place experience, enabling detection of words from any domain. This approach can be useful not only for town and destination brand managers but also for researchers in any field.
The reluctance to the vaccine, mental health, fear of covid-19 and quality of life among Palestinians: an exploratory comparative study in different geographical areas
Authors: Veronese Guido , Ismail Anas , Mahamid Fayez , El-Khodary Basel , Bdier Dana , Diab Marwan
Published: July 2023

Purpose

This study aims to explore the effect of mental health in terms of depression, anxiety, stress, fear of COVID-19 and quality of life (QoL) on the reluctance to be vaccinated in a population of Palestinian adults living in occupied Palestinian territories and Israel.

Design/methodology/approach

The authors recruited 1,122 Palestinian adults who consented to participate in the study; 722 were females, and the mean age of the sample was 40.83 (SD 8.8). Depression, anxiety, and stress scale (DASS), World Health Organization QoL-BREF, FCov-19 and reluctance to the vaccine scale were administered; hierarchical regression analysis was applied to test vaccine reluctance as a dependent variable, and mental health, fear of COVID-19 and QoL as independent variables. This study hypothesized influence of such variables on the vaccine choice with differences due to the participants’ geographical locations.

Findings

Findings showed an effect of mental health, particularly depression, QoL and fear of COVID on vaccine reluctance, with depression and fear of COVID in the West Bank and Gaza, while in Israel, QoL played a role in vaccination choices.

Research limitations/implications

The future needs to be comprehended more thoroughly to discover mutations and fluctuations over time in vaccine hesitancy and the increasing role of psychological distress, diminished QoL and fear of Covid-19. Online recruitment might not have allowed the study to include the most disadvantaged strips of the Palestinian population.

Practical implications

Human rights perspectives must be considered in public health and public mental health policies to ensure the QoL and well-being for the Palestinian population during and following the pandemic.

Social implications

The crumbling of the Palestinian health-care system exacerbated the sense of dread among the population and made them less likely to vaccinate. The pandemic-like spread of Covid-19 prompts a plea for the global community to actively advocate for the urgent re-establishment of equity, autonomy and durability of the medical infrastructure in the occupied territories and equal entitlements for the Palestinians in Israel.

Originality/value

The results demonstrated the importance for public mental health to consider the multiple levels implied in the vaccine refusal in Palestine and Israel among the Palestinian population.
Herding in the Australian stock market during the era of COVID-19: the roles of liquidity, government interventions and mood contagion
Authors: Huynh Nhan , Nguyen Dat Thanh , Tran Quang Thien
Published: July 2023

Purpose

This study explores the economic impact of the COVID-19 crisis on herding behaviour in the Australian equity market by considering liquidity, government interventions and sentiment contagion.

Design/methodology/approach

This study utilizes a daily dataset of the top 500 stocks in the Australian market from January 2009 to December 2021. Both predictive regression and portfolio approaches are employed to consider the impact of COVID-19 on herding intention.

Findings

This study confirms that herding propensity is more pronounced at the beginning of the crisis and becomes less significant towards later phases when reverse herding is more visible. Investors herd more toward sectors with less available information on financial support from the government during the financial meltdown. Conditioning the stock liquidity, herding is only detectable during highly liquid periods and high-liquid stocks, which is more observable during the initial phases of the crisis. Further, the mood contagion from the United States (US) market to Australian market and asymmetric herding intention are evident during the pandemic.

Originality/value

This is the first study to shed further light on the impact of a health crisis on the trading behaviour of Australian investors, which is driven by liquidity, public information and sentiment. Notwithstanding the theoretical contributions to the prior literature, several practical implications are proposed for businesses, policymakers and investors during uncertainty periods.
The heterogeneous impact of house purchase limits policy on housing prices: Comparison between elite and non‐elite school district houses
Authors: Huang Yongbin , Hong Hai
Published: July 2023

The effectiveness of housing purchase limits policies has aroused heated debate, yet few discussed its impact on educational capitalization. We examine the heterogeneous effect of housing purchase limits policy on the price of elite school district houses (ESDH) and non‐elite school district houses. By exploiting second‐hand houses data in Hefei China, we find that the price of ESDH has increased greatly after the limitation, compared with non‐elite school districts. Further we discover that the ESDH have lower depreciation risks, and their price is higher in neighborhoods with smaller dwelling area. Our finding indicates that the limits policy may have exacerbated the educational capitalization.