bluuebunny/crossref_metadata_2025 huggingface dataset:
Human blood exposure toClostridium perfringensepsilon toxin may shed light on erythrocyte fragility during active multiple sclerosis
Authors: Rashid Rumah K. , Eleso Olawale E. , Fischetti Vincent A.
Published: October 2019

During active multiple sclerosis (MS), red blood cells (RBCs) harvested from patients reportedly display increased osmotic fragility and increased cellular volume (macrocytosis). The cause of these abnormalities remains unknown. We have previously proposed thatClostridium perfringensepsilon toxin (ETX) may be a blood-borne trigger for newly forming MS lesions based on its tropism for blood-brain barrier vasculature and CNS myelin. Recently, Gao et al. have reported that ETX binds to and damages human RBCs, leading to hemolysis. Moreover, the authors suggest that purinergic nucleotide (P2) receptor activation amplifies the hemolytic process. Here, we confirm that ETX indeed causes human-specific RBC lysis. However, our data suggest that the hemolytic process is mediated by metal-catalyzed oxidation of the swell-induced, nucleotide-sensitive ICln chloride channel. We use spectrophotometry, flow cytometry and Western blotting to show that ETX targets human RBCs and T lymphocytes via their shared expression of Myelin and Lymphocyte protein (MAL); a protein shown to be both necessary and sufficient for ETX binding and toxicity. ETX likely triggers T cells to release redox-active heavy metals, Cu+and Fe3+, via the lysosomal exocytosis pathway, while RBCs likely release these heavy metals via ETX pore formation within the RBC membrane. Extracellular Cu+and Fe3+may then amplify hemolysis by oxidizing a previously identified heavy metal-binding site within the ICln channel pore, thus deregulating its normal conductance. Elucidating the precise mechanism of ETX-mediated hemolysis may shed light on the underlying etiology of MS, as it would explain why MS RBC abnormalities occur during active disease.

IMPORTANCE

During active MS, numerous reports suggest that circulating RBCs are larger than normal and fragment more easily. The exact trigger(s) for these RBC abnormalities and for newly forming MS lesions remains unidentified. We have proposed that ETX, secreted by the gut bacteriumClostridium perfringens, may be an environmental trigger for newly forming MS lesions. Indeed, ETX has been shown to breakdown the BBB, enter the brain and damage the myelin sheath. Because ETX is typically spread through the circulatory system, we wished to determine how the toxin affects human blood. Provocatively, there has been a recent report that ETX produces cellular abnormalities in human RBCs, reminiscent of what has been described during active MS. In our study, we sought to elucidate the precise mechanism for how ETX causes RBC damage. In addition to triggering BBB breakdown and CNS demyelination, ETX might also explain why RBCs appear abnormal during MS attacks.
Feeding status influences adult vine weevil (coleoptera: curculionidae) behaviour to conspecific volatiles
Authors: Roberts Joe M. , Kundun Jhaman , Pope Tom W.
Published: October 2019

Vine weevil, Otiorhynchus sulcatus F. (Coleoptera: Curculionidae), is widely considered to be one of the most economically important pests of soft-fruit and ornamental crops. The chemical ecology of vine weevil has been extensively studied in the pursuit of a semiochemical lure to improve monitoring tool sensitivity/reliability and develop novel control methods. Although vine weevil adults exhibit a strong tendency to aggregate, the mechanism underlying this behaviour has not, to date, been identified. It is notable, however, that previous studies have not considered the impact of feeding status on vine weevil aggregation behaviour. To investigate the importance of feeding status on aggregation behavior, this study recorded the responses of satiated and starved vine weevil adults to the odour of starved conspecifics. Satiated adults exhibited a preference for the odour of conspecifics while starved vine weevils exhibited no such preference. Therefore, this study provides evidence to support the hypothesis that feeding status is an important factor for vine weevil aggregation.
The primary structural photoresponse of phytochrome proteins captured by a femtosecond X-ray laser
Authors: Claesson Elin , Wahlgren Weixiao Yuan , Takala Heikki , Pandey Suraj , Castillon Leticia , Kuznetsova Valentyna , Henry Léocadie , Carrillo Melissa , Panman Matthijs , Kübel Joachim , Nanekar Rahul , Isaksson Linnéa , Nimmrich Amke , Cellini Andrea , Morozov Dmitry , Maj Michał , Kurttila Moona , Bosman Robert , Nango Eriko , Tanaka Rie , Tanaka Tomoyuki , Fangjia Luo , Iwata So , Owada Shigeki , Moffat Keith , Groenhof Gerrit , Stojković Emina A. , Ihalainen Janne A. , Schmidt Marius , Westenhoff Sebastian
Published: October 2019

Phytochrome proteins control the growth, reproduction, and photosynthesis of plants, fungi, and bacteria. Light is detected by a bilin cofactor, but it remains elusive how this leads to activation of the protein through structural changes. We present serial femtosecond X-ray crystallographic data of the chromophore-binding domains of a bacterial phytochrome at delay times of 1 ps and 10 ps after photoexcitation. The structures reveal a twist of the D-ring, which lead to partial detachment of the chromophore from the protein. Unexpectedly, the conserved so-called pyrrole water is photodissociated from the chromophore, concomitant with movement of the A-ring and a key signalling aspartate. The changes are wired together by ultrafast backbone and water movements around the chromophore, channeling them into signal transduction towards the output domains. We suggest that the water dissociation is key to the phytochrome photoresponse, explaining the earliest steps of how plants, fungi and bacteria sense red light.
c-di-AMP hydrolysis by a novel type of phosphodiesterase promotes differentiation of multicellular bacteria
Authors: Latoscha Andreas , Drexler David Jan , Al-Bassam Mahmoud M. , Kaever Volkhard , Findlay Kim C. , Witte Gregor , Tschowri Natalia
Published: October 2019

Antibiotic-producing Streptomyces use the diadenylate cyclase DisA to synthesize the nucleotide second messenger c-di-AMP but the mechanism for terminating c-di-AMP signaling and the proteins that bind the molecule to effect signal transduction are unknown. Here, we identify the AtaC protein as a new type of c-di-AMP-specific phosphodiesterase that is also conserved in pathogens such as Streptococcus pneumoniae and Mycobacterium tuberculosis. AtaC is monomeric in solution and binds Mn2+ to specifically hydrolyze c-di-AMP to AMP via the intermediate 5’-pApA. As an effector of c-di-AMP signaling, we characterize the RCK-domain protein CpeA as the first c-di-AMP-binding protein to be identified in Streptomyces. CpeA interacts with the predicted cation / proton antiporter, CpeB, linking c-di-AMP signaling to ion homeostasis in actinobacteria. Hydrolysis of c-di-AMP is critical for normal growth and differentiation in Streptomyces, connecting osmotic stress to development. Thus, we present the discovery of two novel components of c-di-AMP signaling in bacteria and show that precise control of this second messenger is essential for osmoregulation and coordinated development in Streptomyces.
Tiled STED Imaging of Extended Sample Regions
Authors: Alvelid Jonatan , Testa Ilaria
Published: October 2019

Stimulated Emission Depletion (STED) nanoscopy has become one of the most used nanoscopy techniques over the last decade. However, most recordings are done in specimen regions no larger than 10–30 × 10–30 µm2 due to aberrations, instability and manual mechanical stages. Here, we demonstrate automated STED nanoscopy of extended sample regions up to 0.5 × 0.5 mm2 by using a back-aperture-stationary beam scanning system. The setup allows up to 80–100 x 80–100 µm2 field of view (FOV) with uniform spatial resolution, a mechanical stage allowing sequential tiling to record larger sample areas, and a feedback system keeping the sample in focus at all times. Taken together, this allows automated recording of theoretically unlimited-sized sample areas and volumes, without compromising the achievable spatial resolution and image quality.
Self-controlled practice and nudging during structural learning of a novel control interface
Authors: Lee Mei-Hua , Jayasinghe Shanie A.L.
Published: October 2019

Self-controlled practice schedules have been shown to enhance motor learning in several contexts, but their effectiveness in structural learning tasks, where the goal is to eventually learn an underlying structure or rule, is not well known. Here we examined the use of self-controlled practice in a novel control interface requiring structural learning. In addition, we examined the effect of ‘nudging’ – i.e., whether altering task difficulty could influence self-selected strategies, and hence facilitate learning. Participants wore four inertial measurement units (IMUs) on their upper body and the goal was to use motions of the upper body to move a screen cursor to different targets presented on the screen. The structure in this task that had to be learned was based on the fact that the signals from the IMUs were linearly mapped to the x- and y-position of the cursor. Participants (N = 62) were split into 3 groups (random, self-selected, nudge) based on whether they had control over the sequence in which they could practice the targets. To test whether participants learned the underlying structure, participants were tested both on the trained targets, as well as novel targets that were not practiced during training. Results showed that during training, the self-selected group showed shorter movement times relative to the random group, and both self-selected and nudge groups adopted a strategy of tending to repeat targets. However, in the test phase, we found no significant differences in task performance between groups, indicating that structural learning was not reliably affected by the type of practice. In addition, nudging participants by adjusting task difficulty did not show any significant benefits to overall learning. These results suggest that although self-controlled practice influenced practice structure and facilitated learning, it did not provide any additional benefits relative to practicing on a random schedule in this task.
Expanding functional protein sequence space using generative adversarial networks
Authors: Repecka Donatas , Jauniskis Vykintas , Karpus Laurynas , Rembeza Elzbieta , Zrimec Jan , Poviloniene Simona , Rokaitis Irmantas , Laurynenas Audrius , Abuajwa Wissam , Savolainen Otto , Meskys Rolandas , Engqvist Martin K. M. , Zelezniak Aleksej
Published: October 2019

De novoprotein design for catalysis of any desired chemical reaction is a long standing goal in protein engineering, due to the broad spectrum of technological, scientific and medical applications. Currently, mapping protein sequence to protein function is, however, neither computationionally nor experimentally tangible1,2. Here we developed ProteinGAN, a specialised variant of the generative adversarial network3that is able to ‘learn’ natural protein sequence diversity and enables the generation of functional protein sequences. ProteinGAN learns the evolutionary relationships of protein sequences directly from the complex multidimensional amino acid sequence space and creates new, highly diverse sequence variants with natural-like physical properties. Using malate dehydrogenase as a template enzyme, we show that 24% of the ProteinGAN-generated and experimentally tested sequences are soluble and display wild-type level catalytic activity in the tested conditionsin vitro, even in highly mutated (>100 mutations) sequences. ProteinGAN therefore demonstrates the potential of artificial intelligence to rapidly generate highly diverse novel functional proteins within the allowed biological constraints of the sequence space.
Topological analysis of TMEM180, a newly identified membrane protein that is highly expressed in colorectal cancer cells
Authors: Anzai Takahiro , Matsumura Yasuhiro
Published: October 2019

New target molecules for diagnosis of and drug development for colorectal cancer (CRC) are always in great demand. Previously, we identified a new colorectal cancer–specific protein, TMEM180, and successfully developed an anti-TMEM180 monoclonal antibody (mAb) for the diagnosis and treatment of CRC. Although TMEM180 is categorized as a member of the cation symporter family and multi-pass membrane protein, little is known about its function. In this study, we examined topology of this membrane protein and analyzed its function. Using a homology model of human TMEM180, we experimentally determined that the protein has 12 transmembrane domains, and that its N-terminal and C-termini are exposed extracellularly. Moreover, we found that the putative cation-binding site of TMEM180 is conserved among orthologs, and that its position is similar to that of melibiose transporter MelB. These results suggest that TMEM180 acts as a cation symporter. Our topological analysis based on the homology model provides insight into functional and structural roles of TMEM180 that may help to elucidate the pathology of CRC.

Highlights

A homology model of human TMEM180 was generated by secondary structure prediction.

Putative cation-binding residues are conserved in TMEM180 orthologs.

Both the N-terminus and C-terminus of TMEM180 are extracellularly exposed.

TMEM180 is a 12-transmembrane protein.

TMEM180 could act as a cation symporter.
Immunotherapy of CT26 murine tumors is characterized by an oligoclonal response against the AH1 tumor rejection antigen
Authors: Probst Philipp , Stringhini Marco , Neri Dario
Published: October 2019

The possibility to cure immunocompetent mice bearing murine CT26 colorectal tumors using cytokine-based therapeutics allows to study the tumor rejection process at a molecular level. Following treatment with L19-mIL12 or F8-mTNF, two antibody fusion proteins which preferentially concentrate a murine cytokine payload at the tumor site, CT26 tumors could be cured in a process that crucially relies on CD8+ T cells. In both settings, the AH1 peptide (derived from the gp70 envelop protein of murine leukemia virus) acted as the main tumor rejection antigen and ~50% of CD8+ T cells in the tumor mass are AH1-specific after therapy. In order to characterize the clonality of the T cell response after successful antibody-cytokine immunotherapy, we isolated CD8+ T cells from tumors and submitted them to T cell receptor (TCR) sequencing. As expected, different TCR sequences were found in different mice, as these molecules originate from a stochastic rearrangement process. CD8+ T cells featuring the ten most abundant TCR sequences represented more than 60% of total CD8+ T cell clones in the tumor mass, but less than 10% in the spleen. Looking at sorted CD8+ T cells from individual animals, AH1-specific TCRs were consistently found among the most abundant sequences. Collectively, these data suggest that the antitumor response driven by two different antibody-cytokine fusions proceeds through an oligoclonal expansion and activation of tumor-infiltrating CD8+ T cells.
Testing the myth of humid versus dry cold: birds do not care
Authors: O’Connor Ryan S. , Vézina François
Published: October 2019

At high air temperatures (Ta) atmospheric water vapor can markedly influence an animal’s heat dissipation by reducing evaporative cooling capacities. At low Tahowever, the impact of increased water vapor on heat exchange has sparsely been investigated, despite human populations at northern latitudes insisting on feeling colder on days with higher humidity (i.e., humid-cold). Here, we aimed to investigate the humid-cold perception by determining whether Black-capped Chickadees (Poecile atricapillus) exhibited greater energy expenditure through increased heat loss under humid-cold conditions relative to dry-cold. We measured resting metabolic rates (RMR) of captive chickadees (n=10) during exposure to two Tatreatments, below freezing (Ta≈ −7°C) and above freezing (Ta≈ 10°C), with either dry or saturated air. We found that Tasubstantially impacted RMR, with RMR ≈1.5-fold greater at −7°C compared with 10°C. Conversely, humidity did not have a statistically significant impact on RMR at either Ta. Our data thus suggest that humidity does not significantly influence an individual’s heat exchange with the environment at cold Ta. This presumably reflects the fact that cold air can hold minimal amounts of water vapor and any possible influence on heat loss is negligible. Instead, we suggest that a greater contributor to the humid-cold myth is the frequency of overcast days during which direct solar radiation is blocked.

Summary statement

Black-capped chickadees significantly increased their resting metabolic rates at air temperatures below freezing relative to air temperatures above freezing, whereas humidity level did not significantly affect resting metabolic rates.
Large body size variation is linked to low communication success in tandem running ants
Authors: Thomas Wagner , Lena Bachenberg , Simone Glaser , Avgousta Oikonomou , Melissa Linn , Christoph Grüter
Published: October 2019

Diversity in animal groups is often assumed to increase group performance. In insect colonies, genetic, behavioral and morphological variation among workers can improve colony functioning and resilience. However, it has been hypothesized that during communication processes, differences between workers, e.g. in body size, could also have negative effects. Tandem running is a common recruitment strategy in ants and allows a leader to guide a nestmate follower to resources. A substantial proportion of tandem runs fail because leader and follower loose contact. Using the antTemnothorax nylanderias a model system, we tested the hypothesis that tandem running success is impaired if leader and follower differ in size. Indeed, we found that the success rate of tandem pairs drops considerably as size variation increases: only ~7% of tandem runs were successful when the leader-follower size difference exceeded 10%, whereas 80% of tandem runs were successful when ants differed less than 5% in body length. One possible explanation is that ant size is linked to the preferred walking speed. Ants did not choose partners of similar size, but extranidal workers were larger than intranidal workers, which could reduce recruitment mistakes because it reduced the chance that very large and very small ants perform tandem runs together. Our results suggest that phenotypic differences between interacting workers can have negative effects on the efficiency of communication processes. Whether phenotypic variation has positive or negative effects is likely to depend on the task and the phenotypic trait that shows variation.
Resource conservation manifests in the genetic code
Authors: Shenhav Liat , Zeevi David
Published: October 2019

Nutrient limitation is a strong selective force, driving competition for resources. However, much is unknown about how selective pressures resulting from nutrient limitation shape microbial coding sequences. Here, we study this ‘resource-driven’ selection using metagenomic and single-cell data of marine microbes, alongside environmental measurements. We show that a significant portion of the selection exerted on microbes is explained by the environment and is strongly associated with nitrogen availability. We further demonstrate that this resource conservation optimization is encoded in the structure of the standard genetic code, providing robustness against mutations that increase carbon and nitrogen incorporation into protein sequences. Overall, we demonstrate that nutrient conservation exerts a significant selective pressure on coding sequences and may have even contributed to the evolution of the genetic code.
Enhancing autophagy by redox regulation extends lifespan inDrosophila
Authors: Lennicke Claudia , Bjedov Ivana , Grönke Sebastian , Menger Katja E. , James Andrew M. , Castillo-Quan Jorge Iván , van Leeuwen Lucie A. G. , Foley Andrea , Buricova Marcela , Adcott Jennifer , Montoya Alex , Kramer Holger B. , Shliaha Pavel V. , Logan Angela , Cabreiro Filipe , Murphy Michael P. , Partridge Linda , Cochemé Helena M.
Published: October 2019

Dysregulation of redox homeostasis has been implicated in the ageing process and the pathology of age-related diseases. To study redox signalling by H2O2in vivo, we established a redox-shifted model by manipulating levels of the H2O2-degrading enzyme catalase inDrosophila. Here we report that ubiquitous over-expression of catalase robustly extends lifespan in flies. As anticipated, these flies were strongly resistant to a range of oxidative stress challenges, but interestingly were sensitive to starvation, which could not be explained by differences in levels of energy reserves. This led us to explore the contribution of autophagy, which is an important mechanism for organismal survival in response to starvation. We show that autophagy is essential for the increased lifespan upon catalase up-regulation, as the survival benefits were completely abolished upon global autophagy knock-down. Furthermore, using a specific redox-inactive knock-in mutant, we highlight thein vivorole of a key regulatory cysteine residue in Atg4a, which is required for the lifespan extension in our catalase model. Altogether, these findings confirm the redox regulation of autophagyin vivoas an important modulator of longevity.
High-fidelity continuum modeling predicts avian voiced sound production
Authors: Jiang W. , Rasmussen J.H. , Xue Q. , Ding M. , Zheng X. , Elemans C.P.H.
Published: October 2019

Voiced sound production is the primary form of acoustic communication in terrestrial vertebrates, particularly birds and mammals, including humans. Developing a causal physics-based model that links descending vocal motor control to tissue vibration and sound requires embodied approaches that include realistic representations of voice physiology. Here we first implement and then experimentally test a high-fidelity three-dimensional continuum model for voiced sound production in birds. Driven by individual-based physiologically quantifiable inputs, combined with non-invasive inverse methods for tissue material parameterization, our model accurately predicts observed key vibratory and acoustic performance traits. These results demonstrate that realistic models lead to accurate predictions and support the continuum model approach as a critical tool towards a causal model of motor control of voiced sound production.
The gift of gab: probing the limits of dynamic concentration-sensing across a network of communicating cells
Authors: Bahadorian Mohammadreza , Zechner Christoph , Modes Carl
Published: October 2019

Many systems in biology and beyond employ collaborative, collective communication strategies for improved efficiency and adaptive benefit. One such paradigm of particular interest is the community estimation of a dynamic signal, when, for example, an epithelial tissue of cells must decide whether to react to a given dynamic external concentration of stress signaling molecules. At the level of dynamic cellular communication, however, it remains unknown what effect, if any, arises from communication beyond the mean field level. What are the limits and benefits to communication across a network of neighbor interactions? What is the role of Poissonian vs. super Poissonian dynamics in such a setting? How does the particular topology of connections impact the collective estimation and that of the individual participating cells? In this letter we construct a robust and general framework of signal estimation over continuous time Markov chains in order to address and answer these questions. Our results show that in the case of Possonian estimators, the communication solely enhances convergence speed of the Mean Squared Error (MSE) of the estimators to their steady-state values while leaving these values unchanged. However, in the super-Poissonian regime, MSE of estimators significantly decreases by increasing the number of neighbors. Surprisingly, in this case, the clustering coefficient of an estimator does not enhance its MSE while reducing total MSE of the population.
Diabetic conditions induce intolerance to accumulation of pathogenic mitochondrial DNAs
Authors: Ogasawara Emi , Katada Shun , Mito Takayuki , Hayashi Jun-Ichi , Nakada Kazuto
Published: October 2019

Marked accumulation of mitochondrial DNA (mtDNA) with a particular pathogenic mutation is necessary for the mutant mtDNA to express its pathogenicity as mitochondrial respiration defects. However, the nuclear genome background, or the physiological status, or both, might also be important for the pathogenic regulation of mutant mtDNAs, because most mitochondrial function is controlled by polypeptides encoded in the nuclear genome. To test this, we generated diabetic mice carrying pathogenic mtDNA with a large-scale deletion (ΔmtDNA) that loses six tRNA genes and seven structural genes essential for mitochondrial respiration. Compared with non-diabetic mice carrying ΔmtDNA, diabetic mice carrying ΔmtDNA showed a decrease in mitochondrial biogenesis regulated by nuclear-encoded genes, and mitochondrial respiration defects and the resultant mitochondrial disease phenotypes were induced even in the case of low loads of ΔmtDNA. In addition, diabetic culture conditions intensified the pathogenicity of human mtDNA with an A3243G point mutation in the tRNALue (UUR) gene. Our results indicated that the diabetic conditions are a modifier that exacerbates mitochondrial respiration defects due to mutant mtDNAs. The finding suggests the possibility that recovery from diabetic conditions might be an effective treatment strategy for some disorders involving both mutant mtDNAs and diabetic signs.

Author Summary

It has been reported that accumulation of pathogenic mutant mitochondrial DNA (mtDNA) and the resultant mitochondrial metabolic dysfunction are associated with a wide variety of disorders, such as mitochondrial diseases, diabetes, neuo-degenerative disorders, and cancers. Considering that most mitochondrial function is regulated by nuclear-genome-encoded polypeptides, it is very important to focus on cooperation between mutant mtDNA, nuclear genetic background, and vital conditions for understanding precise pathogeneses of mtDNA-mediated disorders. By using model cells and mice carrying pathogenic mtDNAs, we report here that diabetic conditions are a modifier for the pathogenic regulation of mutant mtDNAs. Because the onset and progression of diabetes are often associated with aging, our finding suggests that some age-associated disorders with mutant mtDNAs and diabetic complications might be induced partly by enhancement of the pathogenicity of mutant mtDNAs by diabetic conditions.
Brain, music and emotion: An EEG proof-of-concept study on musically continuous, non-personalized emotional responses
Authors: Papatzikis Efthymios , Herbst Anri
Published: October 2019

It has been repeatedly reported that motivation for listening to music is majorly driven by the latter’s emotional effect. There is a relative opposition to this approach, however, suggesting that music does not elicit true emotions. Counteracting this notion, contemporary research studies indicate that listeners do respond affectively to music providing a scientific basis in differentially approaching and registering affective responses to music as of their behavioral or biological states. Nevertheless, no studies exist that combine the behavioral and neuroscientific research domains, offering a cross-referenced neuropsychological outcome, based on a non-personalized approach specifically using a continuous response methodology with ecologically valid musical stimuli for both research domains. Our study, trying to fill this void for the first time, discusses a relevant proof-of-concept protocol, and presents the technical outline on how to multimodally measure elicited responses on evoked emotional responses when listening to music. Specifically, we showcase how we measure the structural music elements as they vary from the beginning to the end within two different compositions, suggesting how and why to analyze and compare standardized, non-personalized behavioral to electroencephalographic data. Reporting our preliminary findings based on this protocol, we focus on the electroencephalographic data collected from n=13 participants in two separate studies (i.e., different equipment and sample background), cross-referencing and cross-validating the biological side of the protocol’s structure. Our findings suggest (a) that all participants – irrespectively of the study – reacted consistently in terms of hemispheric lateralization for each stimulus (i.e., uniform intra-subjective emotional reaction; non-statistically significant differentiation in individual variability) and (b) that diverse patterns of biological representations emerge for each stimulus between the subjects in the two studies (variable inter-subjective emotional reaction; statistically significant differentiation in group variability) pointing towards exogenous to the measurements process factors. We conclude discussing further steps and implications of our protocol approach.
Isolation and characterisation of watermelon (Citrullus lanatus) extracellular vesicles and their cargo
Authors: Timms Kate , Holder Beth , Day Anil , McLaughlin John , Westwood Melissa , Forbes Karen
Published: October 2019

Extracellular vesicles (EVs) facilitate cell-cell communication in animals and are integral to many physiological and pathological processes. Evidence for the presence and function of EVs in plants is limited. Here, we report that EVs derived from watermelon fruit mesocarp are of similar size and morphology to the animal EV subtype known as exosomes. Analysis of EV constituents revealed that watermelon EVs are negative for endoplasmic reticulum markers, and that the miRNA and protein profiles differ from that of watermelon mesocarp cells, suggesting that these EVs are actively synthesised and are not merely cellular debris. Furthermore, we report a panel of proteins found in in watermelon EVs as well as the published proteomes of grape, grapefruit, lemon andArabidopsis thalianaEVs that are novel potential plant EV markers. Bioinformatic analyses suggest that plastids and multivesicular bodies are likely sites of biogenesis for EVs from watermelon and other plants. Predicted functional roles of watermelon EVs include development and metabolism, with several of their cargo molecules likely to be key in regulation of fruit development and ripening. Further understanding of how EVs may contribute to these processes would improve understanding of plant cell-cell communication and could aid in the harnessing of plant EVs for greater temporal control of crop development/ripening for the agricultural and retail industries.
Proteome-scale discovery of protein interactions with residue-level resolution using sequence coevolution
Authors: Green Anna G. , Elhabashy Hadeer , Brock Kelly P. , Maddamsetti Rohan , Kohlbacher Oliver , Marks Debora S.
Published: October 2019

The majority of protein interactions in most organisms are unknown, and experimental methods for determining protein interactions can yield divergent results. Here we use an orthogonal, purely computational method based on sequence coevolution to discover protein interactions at large scale. In the model organism Escherichia coli, 53% of protein pairs in the proteome are eligible for our method given currently available sequenced genomes. When assaying the entire cell envelope proteome, which is understudied due to experimental challenges, we found 620 likely interactions and their predicted structures, increasing the space of known interactions by 529. Our results show that genomic sequencing data can be used to predict and resolve protein interactions to atomic resolution at large scale. Predictions and code are freely available at https://marks.hms.harvard.edu/ecolicomplex and https://github.com/debbiemarkslab/EVcouplings
3,3′-[(1E,1′E)-Hydrazine-1,2-diylidenebis(ethan-1-yl-1-ylidene)]bis(4-hydroxy-6-methyl-2H-pyran-2-one)
Authors: El Alami Abouelhaoul , Hamid Sdassi , El Kihel Abdellatif , Saadi Mohamed , El Ammari Lahcen
Published: October 2019

The title compound, C16H16N2O6, lies about an inversion centre at the mid-point of the N—N bond. The molecule features two intramolecular O—H...N and two C—H...O hydrogen bonds, each of which forms an S(6) ring motif. In the crystal, molecules are linked by C—H...O hydrogen bonds into infinite zigzag chains propagating along the c-axis direction. π–π stacking interactions between the pyrone rings [centroid–centroid distances = 3.975 (2) Å] stack the molecules along b.
The Lion-Dragon Dance in the Chongqing Connectivity Initiative
Authors: Gong Xue
Published: October 2019

Purpose

Since China’s “opening-up” in the late 1970s, Singapore has played a major role in enhancing China’s engagement with the world, especially in economic terms. This traditional relationship is well manifested in the third government-to-government (G–G) project under the BRI, which is known as the Chongqing Connectivity Initiative (CCI). The purpose of this paper is to address the following question: despite Singapore’s initial reluctance to agree on a third G–G project with China, why did Singapore eventually decide to join the CCI?

Design/methodology/approach

This paper draws on archives of over 700 Chinese language media reports and over 400 English language media reports, as well as private interactions with scholars interested in Sino-Singapore relations and with both sides’ officials in charge of the CCI project.

Findings

The paper finds that it is the goal of connecting the region, along with the need to maintain Singapore’s relevance to China and the regional economy that led to Singapore’s participation in the third G–G project. This paper also uses this case to analyse the changes that are taking place in the bilateral economic relations.

Originality/value

Despite wide media coverage, op-ed commentaries and respective government statements, there are a limited number of academic studies on the rationale of the third G–G project and contemporary Sino-Singapore relations in the literature. The scholarship has not addressed the rationale for Singapore’s changing attitude towards CCI and the manner in which the CCI has improved cooperation (or upgraded cooperation to a broader and regional level).
The effects of online store informativeness and entertainment on consumers’ approach behaviors
Authors: Wu Ruijuan , Wang Guiduo , Yan Li
Published: October 2019

Purpose

The purpose of this paper is to examine how informativeness and entertainment, two important online store characteristics, influence consumers’ approach behaviors. The current research also investigates the mechanism and boundary condition behind these relationships.

Design/methodology/approach

The study proposed a conceptual framework that included five variables to understand consumers’ approach behaviors toward online stores. By surveying 307 Chinese online shoppers using a comprehensive questionnaire, the authors collected data that were then used to test the hypotheses. Data were examined using regression analysis.

Findings

The results showed that online store informativeness and entertainment significantly affected consumers’ approach behaviors. In the relationship between these two online store characteristics and consumers’ approach behaviors, pleasure played a mediating role. Hedonic value moderated the effect of informativeness on consumers’ approach behaviors. However, the moderating role of hedonic value was not significant in the relationship between entertainment and consumers’ approach behaviors.

Originality/value

The present study supplements the research on online store characteristics based on the perception of overall online store environmental cues. This paper also examines the online shopping experience of consumers in emerging markets like China.
Affective and cognitive dimensions in cultural identity: scale development and validation
Authors: Pan Xiaoyi , Hao Andy , Guan Cuiling , Hsieh Tsun-Jui
Published: October 2019

Purpose

The purpose of this paper is to provide a conceptualization of the construct of cultural identity (CI) and develop and validate a measurement scale for the construct. This study examines experience-related cognitions and the positive and negative emotional dimensions in cultural identity.

Design/methodology/approach

The paper describes the process of the development of the instrument, the sample, as well as the validation of the instrument. This study performs both exploratory factor analysis and confirmatory factor analysis to examine the reliability and validity of the scale developed.

Findings

The final CI scale has three dimensions: six items for the cognitive dimension, five items for the emotional dimension and seven items for the behavioral dimension. The scale shows internal consistency, reliability, construct validity and nomological validity.

Originality/value

This is the first CI scale to be developed for the measurement of CI of traditional Chinese medicine.
When and why leaders trust followers
Authors: Jawahar I.M. , Stone Thomas H. , Kluemper Don
Published: October 2019

Purpose

Followers’ perceptions of leader trustworthiness affect their trust in the leader (Colquittet al., 2007). However, because positive benefits of trust generally accrue when trust is reciprocated, examining when and why followers’ perceptions of leader trustworthiness elicit leader’s trust in followers may provide heuristic and practical value. Therefore, the purpose of this paper is to examine if followers’ perceptions of leader trustworthiness elicit leaders’ trust in followers, casting follower’s perceptions of leader–member exchange (LMX) quality as a mediator and their perceptions of empowerment as moderating this mediated relationship.

Design/methodology/approach

Followers’ perception of leader trustworthiness was measured at Time 1, followers’ perceptions of empowerment and LMX were measured at Time 2 and leaders’ trust in followers was measured in Time 3. The authors tested the research model with data collected from 347 leader–follower dyads using the three time-lagged surveys as noted above.

Findings

Followers’ perceptions of leader trustworthiness and perceptions of empowerment interacted to influence followers’ perceptions of LMX quality, which in turn influenced leaders’ trust in followers. Thus, LMX mediated the trustworthiness–trust relationship and this mediated relationship became stronger at increasing levels of empowerment.

Practical implications

Being trusted by leaders is beneficial to followers. Training managers in behaviors that elicit employees’ perceptions of manager trustworthiness has the potential to accrue benefits to employees, managers and the organization.

Originality/value

This study is the first to demonstrate that followers’ perception of leader trustworthiness resulted in leaders trusting followers. In addition, the results support a mediating role for LMX and a moderating role for empowerment in the development of leader trust in the follower. Understanding when and why leaders trust followers offers important insights about development of trust between followers and leaders. The authors discuss implications for theory and practice.
Comparing the situation and person-based predictors of work–family conflict among married working professionals in India
Authors: Baral Rupashree
Published: October 2019

Purpose

The purpose of this paper is to ascertain the situation (presence of young children, working hours, social and organizational support) and person-based factors (core self-evaluations) that influence work-family conflict (both work-to-family conflict (WFC) and family-to-work conflict (FWC)) and to examine the relative power of situational factors vs person-based factors in predicting work-family conflict.

Design/methodology/approach

Data were collected from 367 married working professionals from eight organizations in the manufacturing and services sector in India. Hierarchical regression analysis was conducted to test the hypotheses. Usefulness analysis was performed to reveal the unique contribution of the dispositional variables over the situational variables in predicting the variance in work-family conflict.

Findings

Personality factors accounted for more variance in FWC than in WFC, and situational factors accounted for more variance in WFC than in FWC.

Research limitations/implications

Given the limitations associated with a cross-sectional design, caution is needed concerning the inferences drawn. Only a few variables are considered to assess the characteristics of the context.

Practical implications

Organizations should not view the resolution of work-family conflict as the sole responsibility of an individual because of the demonstrated influence of both dispositional and contextual factors on the presence or absence of such conflict. While individuals may strive to have better self-management skills and stay positive in adverse situations, employers may assist them in dealing with work-family demands by introducing need-based support.

Originality/value

The relative importance of situation-based and person-based variables in predicting work-family conflict has rarely been examined on a managerial sample in India. Research on personality-based antecedents of work-home interference is also in its infancy. A better understanding of the factors as they relate to both directions of work-family conflict may help to identify suitable approaches to managing conflict.
Pseudoplastic natural convection flow and heat transfer in a cylindrical vertical cavity partially filled with a porous layer
Authors: Ayoubi Ayoubloo Kasra , Ghalambaz Mohammad , Armaghani Taher , Noghrehabadi Aminreza , Chamkha Ali J.
Published: October 2019

Purpose

This paper aims to theoritically investigate the free convection flow and heat transfer of a non-Newtonian fluid with pseudoplastic behavior in a cylindrical vertical cavity partially filled with a layer of a porous medium.

Design/methodology/approach

The non-Newtonian behavior of the pseudoplastic liquid is described by using a power-law non-Newtonian model. There is a temperature difference between the internal and external cylinders. The porous layer is attached to the internal cylinder and has a thickness of D. Upper and lower walls of the cavity are well insulated. The governing equations are transformed into a non-dimensional form to generalize the solution. The finite element method is used to solve the governing equations numerically. The results are compared with the literature results in several cases and found in good agreement.

Findings

The influence of the thickness of the porous layer, Rayleigh number and non-Newtonian index on the heat transfer behavior of a non-Newtonian pseudoplastic fluid is addressed. The increase of pseudoplastic behavior and increase of the thickness of the porous layer enhances the heat transfer. By increase of the porous layer from 0.6 to 0.8, the average Nusselt number increased from 0.15 to 0.25. The increase of non-Newtonian effects (decrease of the non-Newtonian power-law index) enhances the heat transfer rate.

Originality/value

The free convection behavior of a pseudoplastic-non-Newtonian fluid in a cylindrical enclosure partially filled by a layer of a porous medium is addressed for the first time.
Linking the employee value proposition (EVP) to employee behavioural outcomes
Authors: Arasanmi Christopher N. , Krishna Aiswarya
Published: October 2019

Purpose

The purpose of this paper is to examine the link between employee value proposition (EVP) dimensions, employee commitment and organisational citizenship behaviours (OCBs) in organisations.

Design/methodology/approach

This cross-sectional study collected data from 134 employees of a government department using a survey method. The collected data were analysed with a regression method using Statistical Package for Social Sciences version 24.

Findings

The regression analysis shows that perceived organisational support, and work environment (WE) influence employee commitment. Also, the relationship between organisational commitment (OC) and OCB was found to be significant. The analysis also confirms that OC mediates the relationship between the EVP variables and OCB.

Research limitations/implications

This study is cross-sectional research, future studies may adopt a longitudinal method or multi-sourced data for further research insights. Due to the adopted research design, the findings should be interpreted with this in mind.

Practical implications

This study helps to understand the impact of EVP attributes on employee commitment in organisations. The finding would benefit organisations on the need to enhance EVP fulfilment, and its benefits findings from the study show perceived organisation support and WE affects OC while OC affects OCB. It is crucial for organisations to consider and align EVP strategies in their people management strategies.

Originality/value

This study contributes to the EVP theory by analysing the role of affiliation dimension of the EVP on employee commitment. Prior research appears to have neglected the influence of the EVP on employee commitment.
Linking interactional injustice to EVLN outcomes
Authors: Rai Arpana , Agarwal Upasna A.
Published: October 2019

Purpose

The study aims to examine a moderated mediation model of effects of conscientiousness on the mediating role of psychological contract violation (PCV) on interactional injustice and employees EVLN (exit, voice, loyalty and neglect) outcomes relationships.

Design/methodology/approach

A sample of 422 full-time managerial employees working across different service sector-based Indian organizations was used to test the proposed moderated mediation. The analysis was performed using Hayes’ Process Macro.

Findings

Results revealed that (i) the effect of interactional injustice on employee EVLN outcomes is mediated through PCV and (ii) the strength of this indirect effect is dependent on individual differences in conscientiousness. As such, the overall pattern of relationships supported moderated mediation, in that, the indirect effect of interactional injustice on voice and loyalty through PCV was stronger for employees high (as compared with those low) in conscientiousness.

Research limitations/implications

A cross-sectional design and use of self-reported questionnaire data in the sample are a few limitations of the study.

Originality/value

This study advances the existing literature on interactional injustice by extending its range of outcomes as well as by examining the underlying and intervening conditions in the interactional injustice-outcomes relationship.