bluuebunny/crossref_metadata_2025 huggingface dataset:
Antibodies Raised Against an Aβ Oligomer Mimic Recognize Pathological Features in Alzheimer’s Disease and Associated Amyloid-Disease Brain Tissue
Authors: Kreutzer Adam G. , Parrocha Chelsea Marie T. , Haerianardakani Sepehr , Guaglianone Gretchen , Nguyen Jennifer T. , Diab Michelle N. , Yong William , Perez-Rosendahl Mari , Head Elizabeth , Nowick James S.
Published: May 2023

Antibodies that target the β-amyloid peptide (Aβ) and its associated assemblies are important tools in Alzheimer’s disease research and have emerged as promising Alzheimer’s disease therapies. This paper reports the creation and characterization of a triangular Aβ trimer mimic composed of Aβl7-36β-hairpins, and the generation and study of polyclonal antibodies raised against the Aβ trimer mimic. The Aβ trimer mimic is covalently stabilized by three disulfide bonds at the corners of the triangular trimer to create a homogeneous oligomer. Structural, biophysical, and cell-based studies demonstrate that the Aβ trimer mimic shares characteristics with oligomers of full-length Aβ: X-ray crystallography elucidates the high-resolution structure of the trimer and reveals that four copies of the trimer assemble to form a dodecamer; SDS-PAGE, size exclusion chromatography, and dynamic light scattering reveal that the trimer also forms higher-order assemblies in solution; cell-based toxicity assays show that the trimer elicits LDH release, decreases ATP levels, and activates caspase-3/7 mediated apoptosis. Tmmunostaining studies on brain slices from people who lived with Alzheimer’s disease as well as people who lived with Down syndrome reveal that the polyclonal antibodies raised against the Aβ trimer mimic recognize pathological features including different types of Aβ plaques and cerebral amyloid angiopathy. These findings suggest that the triangular trimer structural motif is important in Alzheimer’s disease and may thus constitute a new structurally defined molecular target for diagnostic and therapy development.

SYNOPSIS

A structurally defined Aβ oligomer mimic is created and studied, and antibodies raised against the Aβ oligomer mimic are used to investigate its relevance to Alzheimer’s disease.
Hatching asynchrony and fitness in a neotropical seabird: second-hatched individuals from highly asynchronous broods are less fit but only during the rearing period
Authors: Ortega Santiago , Rodríguez Cristina , Drummond Hugh
Published: May 2023

Early-life conditions are important determinants of phenotype and fitness. In birds, hatching asynchrony can generate differences in early-life conditions within a brood, which, in turn, can have far reaching fitness consequences for offspring, particularly so for later-hatched nestlings. A plethora of literature has examined consequences of hatching asynchrony during the nestling phase; however, long-term effects remain poorly understood. Using a 33-year population study of the Blue-footed booby (Sula nebouxii) off the Pacific Coast of Mexico, we show that the level of hatching asynchrony affects early- life survival of second-hatched nestlings. Junior boobies from highly asynchronous broods died at younger ages during the rearing period and were less likely to fledge compared to first-hatched offspring. However, level of hatching asynchrony did not have long-term fitness effects on either senior- or junior juveniles or adults. Our results provide insight into how parentally imposed natal environments affect early-life survival and late-life fitness traits in a long-lived seabird.

Highlights

Parentally imposed natal conditions can have far reaching fitness consequences for offspring.

In birds, hatching asynchrony can produce size hierarchies within a brood.

The effects of natural variation in hatching asynchrony on fitness is poorly understood.

High levels of hatching asynchrony are detrimental for junior booby nestlings.

Hatching asynchrony does not affect fitness in the juvenile or adult periods.
Antimicrobial Resistance Profiles of Bacterial Contaminants from a Tertiary Hospital in Kenya: An Urgent Call for Action Against the Global Threat of Antimicrobial Resistance
Authors: Chester Kolek , Briton Kavulavu , Okalebo Faith , Singa Benson , Masheti Mary , Omuom Ian , Odhoch Ochieng , Oduol Chris , Musyimi Robert , Tigoi Caroline , Tickell Kirkby D
Published: May 2023

Background

Hospital-acquired infections (HAIs) represent the most prevalent adverse event among patients in hospital settings. Contamination with pathogenic bacteria that are highly resistant in the hospital environment increases the risk of HAIs.

Objective

The antimicrobial resistance (AMR) patterns of hospital contaminants isolated from highly frequented surfaces in a tertiary hospital in Kenya.

Methods

A total of 62 swabs were collected from selected surfaces, equipment, and health workers’ palms in April 2020. They were cultured and bacterial contaminants were identified using standard microbiological procedures and their AMR patterns were determined using recommended laboratory assays.

Results

Of the 62 swabs collected, 61.3% (n=38) yielded bacterial growth, from which 46 bacteria were isolated. Swab positivity varied across the departments as follows: gynecology wards (78.6%), New Born Unit (NBU) (56.2%), Pediatric ward (61.9%), and Renal Unit (45.5%). Gram negative species comprised 86.96%(n=40) while Gram positive species comprised 13.04%(n=6). Of all the 46 isolates obtained, 36.96% (n=17) were positive for the resistance markers screened. Specifically, 10.9% (n=5) showed both extended-spectrum beta-lactamases (ESBL)and carbapenem-resistant (CR) resistance, while 23.9%(n=11) were positive for ESBL production. The rest were non-resistant strains as shown by negative ESBL at 47.8% (n=22), methicillin sensitivity at 13% (n=6) and vancomycin sensitivity at 2.2% (n=1).Acinetobacterspecies which were most reported, had the highest resistance (36.84% (7/19).

Conclusion

There was a high prevalence of contamination with resistant pathogenic bacteria species.Acinetobacterspecies were the most common pathogen. Interventions are needed to mitigate the problem of resistant HAI.
ADSC-EVs modulate primary human macrophages to an anti-inflammatory phenotypein vitro
Authors: Symonds Emma K C , Black Bianca , Brown Alexander , Meredith Ineke , Currie Margaret , Hally Kathryn E , Danielson Kirsty M
Published: May 2023

Background

EVs released by adipose derived stem cells (ADSCs) have shown promise as a therapeutic for tissue repair and regeneration because of their purported immune-regulatory properties. In this capacity, ADSC-EVs could be beneficial in improving graft retention rates for autologous fat grafting (AFG) post-mastectomy as, currently, grafted tissue rates are reported to be variable and low. Enriching grafted tissue with ADSC-EVs may improve retention rates by modulating macrophages resident within both the breast and lipoaspirate. We aimed to identify key macrophage phenotypes that are modulated by ADSC-EVsin vitro.

Methods

ADSCs were isolated from lipoaspirates of women undergoing AFG and characterised by flow cytometry and differentiation potential. ADSC-EVs were isolated from cell culture media and characterised by tunable resistive pulse sensing (TRPS), transmission electron microscopy (TEM), and Western blot. Primary monocyte-derived macrophages were polarized to an M1-like (GM-CSF, IFNγ) or M2-like phenotype (M-CSF, IL-4) or maintained (M0-like; M-CSF) and, at the time of polarization, ADSC-EVs were co-cultured with macrophages for 48 hrs. Flow cytometry coupled with high-dimensional analysis was used to cluster macrophages post co-culture. A manual gating strategy was generated to recapitulate these clusters and was applied to a repeat experimental run. Both runs were analysed to examine the prevalence of each cluster, representing a unique macrophage phenotype, with and without ADSC-EVs.

Results

Following the addition of ADSC-EVs, M0-like macrophages demonstrated a reciprocal shift of cell distribution from a cluster defined as having a ‘high inflammatory profile’ (CD36+++CD206+++CD86+++; 38.6±14.8% of M1-like macrophages without ADSC-EVs; 16.5±7.0% with ADSC-EVs; p<0.0001) to a cluster with a ‘lower inflammatory’ profile (CD36+CD206+CD86+; 16.6±11.2% to 35±21.5%; p<0.05). There was no shift in M2-like clusters following treatment with ADSC-EVs.

Conclusions

ADSC-EVs are complex regulators of macrophage phenotype that can shift macrophages away from a heightened pro-inflammatory state.
Suitability Evaluation of Toehold Switch and EXPAR for Cell-Free MicroRNA Biosensor Development
Authors: Copeland Caroline E. , Kwon Yong-Chan
Published: May 2023

The development of a robust and cost-effective sensing platform for microRNA (miRNA) is of paramount importance in detecting and monitoring various diseases. Current miRNA detection methods are marred by low accuracy, high cost, and instability. The toehold switch riboregulator has shown promising results in detecting viral RNAs integrated with the cell-free system (CFS). This study aimed to leverage the toehold switch technology to detect miRNA in the CFS and to incorporate the exponential amplification reaction (EXPAR) to bring the detection to clinically relevant levels. We assessed various EXPAR DNA templates under different temperatures and additives to enhance the accuracy of the sensing platform. Furthermore, different structures of toehold switches were tested with either high-concentration synthetic miRNA or EXPAR product to assess sensitivity. Herein, we elucidated the mechanisms of the toehold switch and EXPAR, presented the findings of these optimizations, and discussed the potential benefits and drawbacks of their combined use.
Getting Personal: Brain Decoding of Spontaneous Thought Using Personal Narratives
Authors: Kim Hong Ji , Lux Byeol Kim , Finn Emily S. , Woo Choong-Wan
Published: May 2023

The contents of spontaneous thought and their dynamics are important factors for one’s personality traits and mental health. However, they are difficult to assess because spontaneous thought occurs voluntarily without conscious constraints. Here, we aimed to decode two important content dimensions of spontaneous thought—self-relevance and valence—directly from functional Magnetic Resonance Imaging (fMRI) signals. To train brain decoders, we induced a wide range of levels of self-relevance and emotional valence using individually generated personal stories as well as stories written by others to mimic narrative-like spontaneous thoughts (n= 49). We then tested the brain decoders on two resting-state fMRI datasets (n= 49 and 90) with and without intermittent thought sampling, achieving significant predictions. The default mode and ventral attention networks were important contributors to the predictions. Overall, this study paves the way for the brain decoding of spontaneous thought and its use for clinical applications.
Riding the Wave: Unveiling the Conformational Waves from RBD to ACE2
Authors: Maroli Nikhil
Published: May 2023

The binding affinity between angiotensin-converting enzyme 2 (ACE2) and the receptor-binding domain (RBD) plays a crucial role in the transmission and re-infection of SARS-CoV2. Here, microsecond molecular dynamics simulations revealed that point mutations in the RBD domain induced conformational transitions that determined the binding affinity between ACE2 and RBD. These structural changes propagate through the RBD domain, altering the orientation of both ACE2 and RBD residues at the binding site. ACE2 receptor shows significant structural heterogeneity, whereas its binding to the RBD domain indicates a much greater degree of structural homogeneity. The receptor was more flexible in its unbound state, with the binding of RBD domains inducing structural transitions. The structural heterogeneity observed in the ACE2 unbound form plays a role in the promiscuity of viral entry as it may allow the receptor to interact with various related and unrelated ligands. Furthermore, rigidity may be important for stabilizing the complex and ensuring the proper orientation of the RBD-binding interface with ACE2. The greater structural homogeneity observed in the ACE2-RBD complex revealed the effectiveness of neutralizing antibodies and vaccines that are primarily directed towards the RBD-binding interface. The binding of the B38 monoclonal antibody revealed restricted conformational transitions in the RBD and ACE2 receptor, attributed to its potent binding interaction.
The Host Adapted Fungal Pathogens ofPneumocystisGenus Utilize Genic Regional Centromeres
Authors: Cissé Ousmane H. , Curran Shelly , Folco H. Diego , Liu Yueqin , Bishop Lisa , Wang Honghui , Fischer Elizabeth R. , Davis A Sally , Babb-Biernacki Spenser , Doyle Vinson P. , Richards Jonathan K. , Hassan Sergio A. , Dekker John P. , Khil Pavel P. , Brenchley Jason M. , Grewal Shiv , Cushion Melanie , Ma Liang , Kovacs Joseph A.
Published: May 2023

Centromeres are genomic regions that coordinate accurate chromosomal segregation during mitosis and meiosis. Yet, despite their essential function, centromeres evolve rapidly across eukaryotes. Centromeres are often the sites of chromosomal breaks which contribute to genome shuffling and promote speciation by inhibiting gene flow. How centromeres form in strongly host-adapted fungal pathogens has yet to be investigated. Here, we characterized the centromere structures in closely related species of mammalian-specific pathogens of the fungal phylum of Ascomycota. Methods allowing reliable continuous culture ofPneumocystisspecies do not currently exist, precluding genetic manipulation. CENP-A, a variant of histone H3, is the epigenetic marker that defines centromeres in most eukaryotes. Using heterologous complementation, we show that thePneumocystisCENP-A ortholog is functionally equivalent to CENP-ACnp1ofSchizosaccharomyces pombe. Using organisms from a short-termin vitroculture or infected animal models and ChIP-seq, we identified centromeres in threePneumocystisspecies that diverged ~100 million years ago. Each species has a unique short regional centromere (< 10kb) flanked by heterochromatin in 16-17 monocentric chromosomes. They span active genes and lack conserved DNA sequence motifs and repeats. CENP-C, a scaffold protein that links the inner centromere to the kinetochore appears dispensable in one species, suggesting a kinetochore rewiring. Despite the loss of DNA methyltransferases, 5-methylcytosine DNA methylation occurs in these species, though not related to centromere function. These features suggest an epigenetic specification of centromere function.

Short summary

Pneumocystisspecies offer a suitable genetic system to study centromere evolution in pathogens during host adaptation because of their unique specificity for mammals, and their phylogenetic proximity with the nonpathogenic yeastSchizosaccharomyces pombe, a popular model for cell biology. We used this system to explore how centromeres have evolved after divergence of the two clades ~460 million years ago. To address this question, we established a protocol combining short-term culture and ChIP-seq to characterize centromeres in multiplePneumocystisspecies. We show thatPneumocystishave short epigenetic centromeres that function differently from those inS. pombeand exhibit similarities to centromeres in more distantly related host adapted fungal pathogens.
Choline supplementation in early life improves and low levels of choline can impair outcomes in a mouse model of Alzheimer’s disease
Authors: Chartampila Elissavet , Elayouby Karim S. , Leary Paige , LaFrancois John J. , Alcantara-Gonzalez David , Jain Swati , Gerencer Kasey , Botterill Justin J. , Ginsberg Stephen D. , Scharfman Helen E.
Published: May 2023

Maternal choline supplementation (MCS) improves cognition in Alzheimer’s disease (AD) models. However, effects of MCS on neuronal hyperexcitability in AD are unknown. We investigated effects of MCS in a well-established mouse model of AD with hyperexcitability, the Tg2576 mouse. The most common type of hyperexcitability in Tg2576 mice are generalized EEG spikes (interictal spikes; IIS). IIS also are common in other mouse models and occur in AD patients. Im mouse models, hyperexcitability is also reflected by elevated expression of the transcription factor ΔFosB in the granule cells (GCs) of the dentate gyrus (DG), which are the principal cell type. Therefore we studied ΔFosB expression in GCs. We also studied the the neuronal marker NeuN within hilar neurons of the DG because other studies have reduced NeuN protein expression is a sign of oxidative stress or other pathology. This is potentially important because hilar neurons regulate GC excitability.

Tg2576 breeding pairs received a diet with a relatively low, intermediate or high concentration of choline. After weaning, all mice received the intermediate diet. In offspring of mice fed the high choline diet, IIS frequency declined, GC ΔFosB expression was reduced, and NeuN expression was restored. Using the novel object location task, spatial memory improved. In contrast, offspring exposed to the relatively low choline diet had several adverse effects, such as increased mortality. They had the weakest hilar NeuN immunoreactivity and greatest GC ΔFosB protein expression. However, their IIS frequency was low, which was surprising. The results provide new evidence that a diet high in choline in early life can improve outcomes in a mouse model of AD, and relatively low choline can have mixed effects. This is the first study showing that dietary choline can regulate hyperexcitability, hilar neurons, ΔFosB and spatial memory in an animal model of AD.
Meta-analysis of behavioural research in lizards reveals that phylogeny and viviparity contribute better to animal personality than secretory glands
Authors: Ruiz-Monachesi M.R. , Martínez J.J.
Published: May 2023

Animal personality is defined as an individual’s behavioural consistency across contexts, situations, and time. Understanding the evolution of animal personality requires the integration of macroevolutionary patterns with intraspecific promoters of individual behavioural consistency. In this study, we conducted a meta-analysis to assess the association between lizards’ animal personality and different indicators of sociability (a personality promotor) in a phylogenetic context. In lizards, the presence of both, secretory glands and viviparity have been associated with higher sociability levels. We analysed behavioural repeatability data, including 490 effect sizes from 37 species and 63 studies, considering five categories (activity, aggressivity, boldness, exploration, sociability) while controlling for phylogenetic constraints. For each species, we obtained data on the number of secretory glands and the reproductive mode (oviparous or viviparous). The results showed similar values of repeatability for species with and without glands and an absence of correlation between the number of glands and repeatability data. However, higher repeatability was present in viviparous species than in oviparous species. When we conducted separate analyses for each behavioural type, we found two contrasting patterns for exploration and boldness. Species without glands were more exploratory, while species with glands were bolder. In general, phylogeny explained the observed patterns of repeatability, but boldness, exploration and sociability were poorly explained by evolutionary history among species. This study represents a first step in disentangling the integration among animal personality, life-history and morphology traits under a broad evolutionary context.
Task-anchored grid cell firing is selectively associated with successful path integration-dependent behaviour
Authors: Clark Harry , Nolan Matthew F.
Published: May 2023

Grid firing fields have been proposed as a neural substrate for spatial localisation in general or for path integration in particular. While there are theoretical arguments to support each possibility, it has been challenging to directly test whether and when grid cells contribute to behaviours. Here, we investigate firing of grid and non-grid cells in the medial entorhinal cortex during a location memory task. We find that grid firing can either be anchored to the task environment, or can encode distance travelled independently of the task reference frame. Anchoring varied between and within sessions, while spatial firing of non-grid cells was either coherent with the grid population, or was stably anchored to the task environment. We took advantage of the variability in task-anchoring to evaluate whether and when encoding of location by grid cells might contribute to behaviour. We find that when reward location is indicated by a visual cue performance is similar regardless of whether grid cells are task-anchored or not, arguing against a role for grid representations when location cues are available. By contrast, in the absence of the visual cue, performance was enhanced when grid cells were anchored to the task environment. Our results suggest that anchoring of grid cells to task reference frames selectively enhances performance when path integration is required.
High number of HPAI H5 Virus Infections and Antibodies in Wild Carnivores in the Netherlands, 2020-2022
Authors: Chestakova Irina V. , van der Linden Anne , Martin Beatriz Bellido , Caliendo Valentina , Vuong Oanh , Thewessen Sanne , Hartung Tijmen , Bestebroer Theo , Dekker Jasja , Poerink Bob Jonge , Gröne Andrea , Koopmans Marion , Fouchier Ron , van den Brand Judith M.A. , Sikkema Reina S.
Published: May 2023

In October 2020, a new lineage of clade 2.3.4.4b HPAI virus of the H5 subtype emerged in Europe, resulting in the largest global outbreak of HPAI to date, with unprecedented mortality in wild birds and poultry. The virus appears to have become enzootic in birds, continuously yielding novel HPAI virus variants. The recently increased abundance of infected birds worldwide increases the probability of bird-mammal contact, particularly in wild carnivores. Here, we performed molecular and serological screening of over 500 dead wild carnivores for H5 HPAI virus infection and sequencing of positive materials. We show virological evidence for HPAI H5 virus infection in 0.8%, 1.4% and 9.9% of animals tested in 2020, 2021 and 2022 respectively, with the highest proportion of positives in foxes, polecats and stone martens. We obtained near full genome sequences for seven viruses and detected PB2 amino acid substitutions known to play a role in mammalian adaptation in three of these. Infections were also found in animals without associated neurological signs or mortality. Serological evidence for infection was detected in 20% of the study population. These findings suggest that a higher number of wild carnivores are infected but undetected in current surveillance programs. We recommend increased surveillance in susceptible mammals, irrespective of the presence of neurological signs or encephalitis.
Fluctuation of lysosomal protein degradation in neural stem cells of postnatal mouse brain
Authors: Zhang He , Ishii Karan , Shibata Tatsuya , Ishii Shunsuke , Hirao Marika , Lu Zhou , Takamura Risa , Kitano Satsuki , Miyachi Hitoshi , Kageyama Ryoichiro , Itakura Eisuke , Kobayashi Taeko
Published: May 2023

Lysosomes are intracellular organelles responsible for degrading diverse macromolecules delivered from several pathways, such as the endo-lysosomal and autophagic pathways. Recent reports have suggested that lysosomes are essential in regulating neural stem cells in developing, adult, and aged brains. However, the activity of these lysosomes has not yet been monitored in these brain tissues. Here, we report a new probe to measure lysosomal protein degradation in brain tissue by immunostaining. Our results demonstrate the fluctuation of lysosomal protein degradation in neural stem cells depending on age and brain disorder. Neural stem cells increase lysosomal activity during hippocampal development in the dentate gyrus, but aging and aging-related disease reduces their activity. In addition, physical exercise increases lysosomal activity in neural stem cells and astrocytes. We hypothesize three different stages of lysosomal activity: the increase in development, the stable state for the adult stage, and the reduction by damages with age or disease.
Quantifying the relationship between cell proliferation and morphology during development of the face
Authors: Green Rebecca M. , Lo Vercio Lucas D. , Dauter Andreas , Barretto Elizabeth C. , Devine Jay , Vidal-García Marta , Marchini Marta , Robertson Samuel , Zhao Xiang , Mahika Anandita , Shakir M. Bilal , Guo Sienna , Boughner Julia C. , Dean Wendy , Lander Arthur D. , Marcucio Ralph S. , Forkert Nils D. , Hallgrímsson Benedikt
Published: May 2023

Morphogenesis requires highly coordinated, complex interactions between cellular processes: proliferation, migration, and apoptosis, along with physical tissue interactions. How these cellular and tissue dynamics drive morphogenesis remains elusive. Three dimensional (3D) microscopic imaging poses great promise, and generates elegant images. However, generating even moderate through-put quantified images is challenging for many reasons. As a result, the association between morphogenesis and cellular processes in 3D developing tissues has not been fully explored. To address this critical gap, we have developed an imaging and image analysis pipeline to enable 3D quantification of cellular dynamics along with 3D morphology for the same individual embryo. Specifically, we focus on how 3D distribution of proliferation relates to morphogenesis during mouse facial development. Our method involves imaging with light-sheet microscopy, automated segmentation of cells and tissues using machine learning-based tools, and quantification of external morphology via geometric morphometrics. Applying this framework, we show that changes in proliferation are tightly correlated to changes in morphology over the course of facial morphogenesis. These analyses illustrate the potential of this pipeline to investigate mechanistic relationships between cellular dynamics and morphogenesis during embryonic development.
The essential domain of FtsN triggers cell division by promoting interaction between FtsL and FtsI
Authors: Park Kyung-Tae , Park David Johnson , Pichoff Sebastien , Du Shishen , Lutkenhaus Joe
Published: May 2023

Cell division in bacteria requires the activation of FtsWI at the division site to synthesize septal peptidoglycan. InE. coliFtsN activates FtsWI and a previous model posited that the essential domain of FtsN (EFtsN) acts on FtsQLB causing conformational changes so that a domain of FtsL, called AWI (AWIFtsL), contacts FtsI resulting in activation of FtsW. In this study we use genetic analysis along with an AlphaFold2 model to test this activation model. Based on our findings we propose an updated model wherein theAWIFtsL and FtsI interaction is stabilized byEFtsN to activate FtsW and that this interaction is enhanced by theCytoFtsN-FtsA interaction. Thus, FtsN acts as both a sensor for divisome assembly and an activator. In addition, we elucidate the role played by two critical FtsL residues in FtsW activation.
Thioflavin T In-gel Stain to Study Protein Misfolding in Frozen Tissue Specimens
Authors: Oldam Joseph , Tchernyshyov Irina , Van Eyk Jennifer E. , Troncoso Juan , Glabe Charles G. , Agnetti Giulio
Published: May 2023

There are limited options to quantify and characterize amyloid species from biological samples in a simple fashion. Thioflavin T (ThT) has now been used for decades to stain amyloid fibrils but to our knowledge we were the first to use it in-gel. Thioflavin T in-gel stain is convenient as it is fast, inexpensive, available to most labs, compatible with other fluorescent stains and downstream analyses such as mass spectrometry (MS).
Can BioSAXS Detect Ultrastructural Changes Of Antifungal Compounds InCandida Albicans? – An Exploratory Study
Authors: Hilpert Kai , Rumancev Christoph , Gani Jurnorain , Collis Dominic W. P. , Lopez-Perez Paula Matilde , Garamus Vasil M. , Mikut Ralf , Rosenhahn Axel
Published: May 2023

The opportunistic yeastCandida albicansis the most common cause of candidiasis. With only four classes of antifungal drugs on the market, resistance is becoming a problem in the treatment of fungal infections, especially in immunocompromised patients. The development of novel antifungal drugs with different modes of action is urgent. In 2016, we developed a groundbreaking new medium-throughput method to distinguish the effects of antibacterial agents. Using small-angle X-ray scattering for biological samples (BioSAXS), it is now possible to screen hundreds of new antibacterial compounds and select those with the highest probability for a novel mode of action. However, yeast (eukaryotic) cells are highly structured compared to bacteria and the action of an antifungal drug might leave most structures unchanged. In the pioneering work described here, we explored the possibility if BioSAXS can be used to measure the ultrastructural changes ofCandida albicansdirectly or indirectly induced by antifungal compounds. For this exploratory study, we used the well-characterized antifungal drug flucytosine. BioSAXS measurements were performed on the synchrotron P12 BioSAXS beamline, EMBL (DESY, Hamburg) on treated and untreated yeastC. albicans. BioSAXS curves were analysed using principal component analysis (PCA). The PCA showed that flucytosine-treated and untreated yeast were separated. Based on that success further measurements were performed on five antifungal peptides (1. Cecropin A-melittin hybrid [CA(1-7)M(2-9)], KWKLFKKIGAVLKVL; 2. Lasioglossin LL-III, VNWKKILGKIIKVVK; 3. Mastoparan M, INLKAIAALAKKLL; 4. Bmkn2, FIGAIARLLSKIFGKR; and 5. optP7, KRRVRWIIW). The ultrastructural changes ofC. albicansindicate that the peptides may have different modes of action compared to Flucytosine as well as to each other, except for the Cecropin A-melittin hybrid [CA(1-7)M(2-9)] and optP7, showing very similar effects onCandida albicans. This very first study demonstrates that BioSAXS shows great promise to be used for antifungal drug development. The use of such a tool like BioSAXS could accelerate and de-risk antifungal drug development, however, further experiments are necessary to establish this application.
Regeneration from three cellular sources and ectopic mini-retina formation upon neurotoxic retinal degeneration inXenopus
Authors: Karine Parain , Chesneau Albert , Locker Morgane , Borday Caroline , Muriel Perron
Published: May 2023

Regenerative abilities are not evenly distributed across the animal kingdom. Interestingly, the underlying modalities are also highly variable, even among closely related species. In fish or amphibians, retinal repair can involve the mobilization of different cellular sources, including stem cells of the ciliary marginal zone (CMZ), retinal pigmented epithelial (RPE) cells, or Müller glia. The mechanisms that trigger the recruitment of one cell type over another remain elusive. To investigate whether the magnitude of retinal damage might influence the regeneration modality of theXenopusretina, we developed a model based on cobalt chloride (CoCl2) intraocular injection, allowing for a dose-dependent control of cell death extent. Analyses inXenopus laevisrevealed that limited CoCl2-mediated neurotoxicity only triggers cone cell loss and results in a few Müller glia cells reentering the cell cycle, without affecting CMZ cell activity or recruiting RPE cells. Conversely, we found that severe CoCl2-induced retinal degeneration not only potentializes the proliferative response of Müller cells, but also enhances CMZ cell proliferation and, unexpectedly triggers an RPE reprogramming event. Although Müller glia could not regenerate cones under these conditions, both CMZ and RPE-derived proliferative cells could. Strikingly, RPE reprogrammed cells self-organized into an ectopic layered mini retina-like structure laid on top of the original retina. It is thus likely that the injury paradigm determines the awakening of different stem-like cell populations exhibiting distinct neurogenic capacities. Besides, we surprisingly found thatXenopus tropicalisalso has the ability to recruit Müller cells and reprogram its RPE following CoCl2-induced damage, whereas only CMZ cell proliferation was reported in previously examined degenerative models. Altogether, these findings highlight the critical role of the injury paradigm and reveal that three cellular sources can be reactivated in the very same degenerative model.
The diminished ovarian reserve with chronic stress induced by tripterygium with chronic unpredictable mild stress in SD rats
Authors: Li Yanhua , Wang Wei , Liu Jun
Published: May 2023

Aim

To establish a rat model of DOR combined with chronic unpredictable mild stress (CUMS), and to explore the effect of chronic adverse psychological stress on ovarian reserve dysfunction, so as to provide experimental basis for further research.

Methods

The rats were randomly divided into control group, CUMS group, DOR group and DOR +CUMS group, with 10 rats in each group,given fed normally, chronic mild unpredictable stress, Tripterygium glycoside tablets and Tripterygium glycoside tablets with CUMS intervention in proper order for 21 days. We observed the body mass, estrous cycle, behavioral testing, the hematoxylin and eosin (H&E) staining of ovarian tissue,the serum levels (E2, FSH, 5-HT and GnRH)and Apoptotic granulosa cells of ovarian tissue.

Results

After an 21-days exposure, in DOR group or DOR+CUMS group the serum levels of E2 was reduced and the FSH was raised. In DOR group, the estrous cycle was disordered, the ovary was slightly atrophied and the ovarian tissue structure was not clear, the number of follicles and the content of follicular fluid were small, the cell layers was reduced, and inflammatory cell infiltration was visible, the change was more obvious in DOR+CUMS group. In CUMS group and DOR+CUMS group, the OFT, SPT and 5-HT were lower and the GnRH was higher than in control group. About the TUNEL, the AI in the DOR group, the CUMS group and DOR+CUMS group were higher.

Conclusions

Our outcomes state that we could established an rat model of psychological stress-induced DOR successfully which can be used for further study.
The chicken chorioallantoic membrane model for isolation of CRISPR/cas9-based HSV-1 mutant expressing tumor suppressor p53
Authors: Kelishadi Mishar , Shahsavarani Hosein , Tabarraei Alijan , Shokrgozar Mohammad Ali , Teimoori-Toolabi Ladan , Azadmanesh Kayhan
Published: May 2023

Oncolytic viruses (OVs) have emerged as a novel cancer treatment modality, which selectively target and kill cancer cells while sparing normal ones. Among them, engineered Herpes Simplex Virus type 1 has been proposed to be employed as a potential treatment of cancer and was moved to phase III clinical trials. In this study, to improve oncoselectivity and oncotoxicity properties, the UL39 gene of the ICP34.5 deleted HSV-1 was manipulated with the insertion of the EGFP-p53 expression cassette utilizing CRISPR/ Cas9-mediated editing genome. The ΔUL39/Δγ34.5/HSV1-p53 mutant was isolated using the chorioallantoic membrane (CAM) of fertilized chicken eggs as a complementing membrane to support the growth of the viruses with gene deficiencies. Phenotypic characterization of ΔUL39/Δγ34.5/HSV1-p53-infected cells was compared with the parent Δγ34.5/HSV-1 in vitro. Our results indicate that the CAM model can be a promising strategy for isolating recombinant virus such as HSV-1-P53 that is unable to replicate in cell lines due to the death induced by exogenous p53 during virus replication.
Beyond rhythm – A framework for understanding the frequency spectrum of neural activity
Authors: Perrenoud Quentin , Cardin Jessica A.
Published: May 2023

Cognitive and behavioral processes are often accompanied by changes within well-defined frequency bands of the local field potential (LFP i.e., the voltage induced by neuronal activity). These changes are detectable in the frequency domain using the Fourier transform and are often interpreted as neuronal oscillations. However, aside some well-known exceptions, the processes underlying such changes are difficult to track in time, making their oscillatory nature hard to verify. In addition, many non-periodic neural processes can also have spectra that emphasize specific frequencies. Thus, the notion that spectral changes reflect oscillations is likely too restrictive. In this study, we propose a simple yet versatile framework to understand the frequency spectra of neural recordings. Using simulations, we derive the Fourier spectra of periodic, quasi-periodic and non-periodic neural processes having diverse waveforms, illustrating how these attributes shape their spectral signatures. We then show how neural processes sum their energy in the local field potential in simulated and real-world recording scenarios. We find that the spectral power of neural processes is essentially determined by two aspects: 1) the distribution of neural events in time and 2) the waveform of the voltage induced by single neural events. Taken together, this work guides the interpretation of the Fourier spectrum of neural recordings and indicates that power increases in specific frequency bands do not necessarily reflect periodic neural activity.
Benchmarking Gene Regulatory Network Inference Methods on Simulated and Experimental Data
Authors: Saint-Antoine Michael , Singh Abhyudai
Published: May 2023

Although the challenge of gene regulatory network inference has been studied for more than a decade, it is still unclear how well network inference methods work when applied to real data. Attempts to benchmark these methods on experimental data have yielded mixed results, in which sometimes even the best methods fail to outperform random guessing, and in other cases they perform reasonably well. So, one of the most valuable contributions one can currently make to the field of network inference is to benchmark methods on experimental data for which the true underlying network is already known, and report the results so that we can get a clearer picture of their efficacy. In this paper, we report results from the first, to our knowledge, benchmarking of network inference methods on single cellE. colitranscriptomic data. We report a moderate level of accuracy for the methods, better than random chance but still far from perfect. We also find that some methods that were quite strong and accurate on microarray and bulk RNA-seq data did not perform as well on the single cell data. Additionally, we benchmark a simple network inference method (Pearson correlation), on data generated through computer simulations in order to draw conclusions about general best practices in network inference studies. We predict that network inference would be more accurate using proteomic data rather than transcriptomic data, which could become relevant if highthroughput proteomic experimental methods are developed in the future. We also show through simulations that using a simplified model of gene expression that skips the mRNA step tends to substantially overestimate the accuracy of network inference methods, and advise against using this model for futurein silicobenchmarking studies.
Dissecting genetic correlation and pleiotropy through a genetic cross
Authors: Cai Haoran , Geiler-Samerotte Kerry , Des Marais David L.
Published: May 2023

Genetic correlation represents an important class of evolutionary constraint, which is itself evolvable. Empirical studies have found mixed results on whether genetic correlations change rapidly or slowly. This uncertainty challenges our ability to predict the outcome of selection. Despite the tremendous diversity and complexity of life forms, there are certain forms of life that are never observed. This might be because of developmental biases that restrict how organisms can evolve, or because they have low fitness in any environment yet available on Earth. Given that both developmental bias and selection can generate similar phenotypes, it is difficult to distinguish between the two causes of evolutionary stasis among related taxa. For example, remarkably invariant traits are observed spanning million years, such as wing shape inDrosophilawherein qualitative differences are rare within genera. Here, we ask whether the absence of certain combinations of traits, as indicated by genetic correlation, reflects developmental bias. However, much confusion and controversy remain over definitions of developmental bias, and probing it is challenging. We thus present a novel approach aiming to dissect genetic correlations and estimate the relative contribution of developmental bias in maintaining genetic correlations. We do so by leveraging a common but under-utilized type of data: genetic crosses. Through empirical analyses, we find that our approach can distinguish whether genetically correlated traits are developmentally constrained to covary. We also find that our developmental bias metric is an indicator of genetic correlation stability across conditions. Our framework presents a feasible way to dissect the mechanisms underlying genetic correlation and pleiotropy.
A developmental gradient reveals biosynthetic pathways to eukaryotic toxins in monocot geophytes
Authors: Mehta Niraj , Meng Yifan , Zare Richard , Kamenetsky-Goldstein Rina , Sattely Elizabeth
Published: May 2023

Numerous eukaryotic toxins that accumulate in geophytic plants are valuable in the clinic, yet their biosynthetic pathways have remained elusive. A lead example is the >150 Amaryllidaceae alkaloids (AmAs) including galantamine, an FDA-approved treatment for Alzheimer’s disease. We show that while AmAs accumulate to high levels in many tissues in daffodils, biosynthesis is localized to nascent, growing tissue at the base of leaves. A similar trend is found for the production of steroidal alkaloids (e.g. cyclopamine) in corn lily. This model of active biosynthesis enabled elucidation of a complete set of biosynthetic genes for the production of AmAs. Taken together, our work sheds light on the developmental and enzymatic logic of diverse alkaloid biosynthesis in daffodil. More broadly, it suggests a paradigm for biosynthesis regulation in monocot geophytes where plants are protected from herbivory through active charging of newly formed cells with eukaryotic toxins that persist as aboveground tissue develops.
High temperature corrosion behaviour of ZrO2 reinforced Cr2O3 composite coatings in molten salt environment
Authors: Goyal Khushdeep , Singh Davinder , Singh Harvinder , Singh Charanjit
Published: May 2023

Purpose

This paper aims to investigate the high temperature corrosion behaviour of ZrO2-reinforced Cr2O3 matrix-based composite coatings on ASTM-SA213-T-22 steel at 900°C in molten salt environment. The different coatings were deposited by high velocity oxy fuel (HVOF) method.

Design/methodology/approach

Hot corrosion studies were conducted in simulated boiler environment in silicon carbide tube furnace at 900°C for 50 cycles on bare and HVOF-coated boiler steel specimens. Each cycle consisted 50 h of heating in the simulated boiler environment followed by 20 min of cooling in air. The weight change measurements were performed after each cycle to establish the kinetics of corrosion using thermogravimetric technique. X-ray diffraction and scanning electron microscopy techniques were used to analyse the corroded specimens.

Findings

The addition of 20 Wt.% ZrO2 in Cr2O3 helped reduce corrosion rate by 89.25% as compared to that of uncoated specimen. The phase analysis revealed the presence of Cr2O3 and ZrO2 phases in composite coating matrix, which may have prevented the base metal from interacting with the corrosive elements present in the highly aggressive environment and thus had increased the resistance to hot corrosion.

Originality/value

It should be mentioned here that high temperature corrosion behaviour of thermally sprayed ZrO2–Cr2O3 composite coatings has never been studied, and to the best of the authors’ knowledge, it is not available in the literature. Hence, present investigation can provide valuable information for application of ZrO2-reinforced coatings in high temperature fuel combustion environments.
Intellectual capital and performance: evidence from SMEs in Vietnam
Authors: Kim Seh Young , Tran Dai Binh
Published: May 2023

Purpose

This paper investigated the relationship between intellectual capital (IC)/its components, and the business performance of Vietnamese small and medium enterprises (SMEs).

Design/methodology/approach

The panel data set was obtained from the Vietnam SME database. Using the value-added intellectual coefficient (VAIC) approach for IC measurement, this paper employs various panel data estimation approaches, including fixed effects (FE) and the generalized method of moments (GMM), to examine the relationship between IC and the financial performance of SMEs in Vietnam.

Findings

The result suggests that the value creation activities of SMEs in Vietnam mainly occur on the basis of physical and financial capital. In other words, the findings indicate that Vietnamese SMEs mainly depend on physical and financial capital to profit: they have not fully utilized their human capital and structural capital, two main components of IC for value creation.

Practical implications

The results underline the urgency of effective management of tangible and IC to boost the utilization of human and structural capital to increase the profitability of Vietnamese SMEs. The results lead to suggesting a series of policy recommendations to achieve the objective.

Originality/value

This paper is the first to examine the relationship between IC and the financial performance of SMEs in Vietnam, contributing to the literature on IC in emerging countries.
The interplay of abusive supervision and coworker incivility on the turnover intention of frontliners: a mediation effect of work stress
Authors: Rahman Md Mostafizur
Published: May 2023

Purpose

Drawing on the conservation of resources theory, the present study aims to design and explore the influence of abusive supervision and coworker incivility on turnover intention among frontline employees (FLEs). Besides the mediating effects of work stress between abusive supervision and turnover intention, coworker incivility and turnover intention also be explored.

Design/methodology/approach

Data from 311 FLEs are collected by a self-administered structured questionnaire and analyzed by confirmatory factor analysis and structural equation model.

Findings

The empirical results established that abusive supervision and coworker incivility significantly predicts work stress and work stress significantly predicts turnover intention. Abusive supervision significantly predicts a positive relationship with turnover intention, whereas coworker incivility with turnover intention is vis-à-vis. Besides, abusive supervision and coworker incivility significantly predict turnover intention via work stress. The study further illustrated the control variables, e.g. education, experience, and proactive personality of FLEs.

Research limitations/implications

The study finds abusive supervision and coworker incivility as stressors in the emerging economy for FLEs. However, coworker incivility on turnover intention cannot predict as expected because the roles of the supervisor and coworker are different in this context.

Practical implications

The continuous support of supervisors and coworkers can reduce the stress and consequences of reducing the intention of turnover of FLEs. The concerns can enhance their support by using respect and credit for work, maintaining privacy, providing proper feedback, being sensible to the performance, and entitlement to any achievement. They also suggest ensuring a work environment of privacy, fair treatment, importance to suggestions, and ascertaining punishment for any colleague's mistreatment.

Social implications

The frontliners always contribute a large pie of output for any organization. Supervisors and coworkers impact the day-to-day life of FLEs.

Originality/value

As a study on FLEs in the context of evolving economy, the investigation fulfills the inconsistencies of the previous result with the mediating role of work stress with a strong theoretical base.