bluuebunny/crossref_metadata_2025_split huggingface dataset:
A single polymorphic residue in humans underlies species-specific restriction of HSV-1 by the antiviral protein MxB
Authors: Bayer Avraham , Child Stephanie J. , Malik Harmit S. , Geballe Adam P. 
Published: May 2023

AbstractMyxovirus resistance proteins (MxA and MxB) are interferon-induced proteins that exert antiviral activity against a diverse range of RNA and DNA viruses. In primates, MxA has been shown to inhibit myxoviruses, bunyaviruses, and hepatitis B virus, whereas MxB restricts retroviruses and herpesviruses. As a result of their conflicts with viruses, both genes have been undergoing diversifying selection during primate evolution. Here, we investigate how MxB evolution in primates has affected its restriction of herpesviruses. In contrast to human MxB, we find that most primate orthologs, including the closely related chimpanzee MxB, do not inhibit HSV-1 replication. However, all primate MxB orthologs tested restrict human cytomegalovirus. Through the generation of human and chimpanzee MxB chimeras we show that a single residue, M83, is the key determinant of restriction of HSV-1 replication. Humans are the only primate species known to encode a methionine at this position, whereas most other primate species encode a lysine. Residue 83 is also the most polymorphic residue in MxB in human populations, with M83 being the most common variant. However, ∼2.5% of human MxB alleles encode a threonine at this position, which does not restrict HSV-1. Thus, a single amino acid variant in MxB, which has recently risen to high frequency in humans, has endowed humans with HSV-1 antiviral activity.ImportanceHerpesviruses present a major global disease burden. Understanding the host cell mechanisms that block viral infections as well as how viruses can evolve to counteract these host defenses is critically important for understanding viral disease pathogenesis, and for developing therapeutic tools aimed at treating or preventing viral infections. Additionally, understanding how these host and viral mechanisms adapt to counter one another can aid in identifying the risks of, and barriers to, cross-species transmission events. As highlighted by the recent SARS-CoV-2 pandemic, episodic transmission events can have severe consequences for human health. This study reveals that the major human variant of the antiviral protein MxB inhibits the human pathogen HSV-1, whereas human minor variants and orthologous MxB genes from even closely related primates do not. Thus, in contrast to the many antagonistic virus-host interactions in which the virus is successful in thwarting the defense systems of their native hosts, in this case the human gene appears to be at least temporarily winning at this interface of the primate-herpesviral evolutionary arms race. Our findings further show that a polymorphism at amino acid 83 in a small fraction of the human population is sufficient to abrogate MxB’s ability to inhibit HSV-1, which could have important implications for human susceptibility to HSV-1 pathogenesis.
Essential role of the Conserved Oligomeric Golgi complex inToxoplasma gondii
Authors: Marsilia Clem , Batra Mrinalini , Pokrovskaya Irina D. , Wang Chengqi , Chaput Dale , Naumova Daria A. , Lupashin Vladimir V. , Suvorova Elena S. 
Published: May 2023

ABSTRACTSurvival of the apicomplexan parasiteToxoplasma gondiidepends on the proper functioning of many glycosylated proteins. Glycosylation is performed in the major membranous organelles ER and Golgi apparatus that constitute a significant portion of the intracellular secretory system. The secretory pathway is bidirectional: cargo is delivered to target organelles in the anterograde direction, while the retrograde flow maintains the membrane balance and proper localization of glycosylation machinery. Despite the vital role of the Golgi in parasite infectivity, little is known about its biogenesis in apicomplexan parasites. In this study we examinedT. gondiiConserved Oligomeric Golgi (COG) complex and determined that, contrary to predictions,T. gondiiexpresses the entire eight-subunit complex and each complex subunit is essential for tachyzoite growth. Deprivation of the COG complex induces a pronounced effect on Golgi and ER membranes, which suggests theT. gondiiCOG complex has wider role in intracellular membrane trafficking. We demonstrated that besides its conservative role in protein glycosylation and retrograde intra-Golgi trafficking, the COG complex also interacted with anterograde and novel transport machinery. Furthermore, we identified coccidian-specific components of the Golgi transport system: TgUlp1 and TgGlp1. Protein structure and phylogenetic analyses revealed that TgUlp1 is an adaptation of the conservative Golgi tethering factor Uso1/p115, and together with Golgi-localized TgGlp1, TgUlp1 showed dominant interactions with the trafficking machinery that predicted to operate the endosome-to-Golgi recycling. Together, our study showed thatT. gondiihas expanded function of the conservative Golgi tethering COG complex and evolved additional regulators of the transport likely to serve parasite-specific secretory organelles.
Identification of PS1/gamma-secretase and glutamate transporter GLT-1 interaction sites
Authors: Perrin Florian , Sinha Priyanka , Mitchell Shane , Maesako Masato , Berezovska Oksana 
Published: May 2023

AbstractThe recently discovered interaction between Presenilin 1 (PS1), a catalytic subunit of γ-secretase responsible for generating amyloid-β (Aβ) peptides, and GLT-1, a major glutamate transporter in the brain (EAAT2) provides a mechanistic link between these two key factors involved in Alzheimer’s disease (AD) pathology. Modulating this interaction can be crucial to understand the consequence of such crosstalk in AD context and beyond. However, the interaction sites between these two proteins are unknown. Herein, we utilized an alanine scanning approach coupled with FRET-based fluorescence lifetime imaging microscopy (FLIM) to identify the interaction sites between PS1 and GLT-1 in their native environment within intact cells. We found that GLT-1 residues at position 276 to 279 (TM5) and PS1 residues at position 249 to 252 (TM6) are crucial for GLT-1/PS1 interaction. These results have been cross validated using AlphaFold Multimer prediction. To further investigate whether this interaction of endogenously expressed GLT-1 and PS1 can be prevented in primary neurons, we designed PS1/GLT-1 cell-permeable peptides (CPPs) targeting the PS1 or GLT-1 binding site. We used HIV TAT domain to allow for cell penetration which was assayed in neurons. First, we assessed the toxicity and penetration of CPPs by confocal microscopy. Next, to ensure the efficiency of CPPs, we monitored the modulation of GLT-1/PS1 interaction in intact neurons by FLIM. We saw significantly less interaction between PS1 and GLT-1 with both CPPs. Our study establishes a new tool to study the functional aspect of GLT-1/PS1 interaction and its relevance in normal physiology and AD models.
Neuropsychology of cognitive aging in rhesus monkeys
Authors: Baxter Mark G. , Roberts Mary T. , Roberts Jeffrey A. , Rapp Peter R. 
Published: May 2023

AbstractAged rhesus monkeys, like aged humans, show declines in cognitive function. We present cognitive test data from a large sample of male and female rhesus monkeys, 34 young (3.5-13.6 years) and 71 aged (19.9-32.5 years of age at the start of cognitive testing). Monkeys were tested on spatiotemporal working memory (delayed response), visual recognition memory (delayed nonmatching-to-sample), and stimulus-reward association learning (object discrimination), tasks with an extensive evidence base in nonhuman primate neuropsychology. On average, aged monkeys performed worse than young on all three tasks. Acquisition of delayed response and delayed nonmatching-to-sample was more variable in aged monkeys than in young.Performance scores on delayed nonmatching-to-sample and object discrimination were associated with each other, but neither was associated with performance on delayed response. Sex and chronological age were not reliable predictors of individual differences in cognitive outcome among the aged monkeys. These data establish population norms for cognitive tests in young and aged rhesus monkeys in the largest sample reported to date. They also illustrate independence of cognitive aging in task domains dependent on the prefrontal cortex and medial temporal lobe.(181 words)
mRNA condensation fluidizes the cytoplasm
Authors: Xie Ying , Liu Tiewei , Gresham David , Holt Liam J 
Published: May 2023

AbstractThe intracellular environment is packed with macromolecules of mesoscale size, and this crowded milieu significantly influences cell physiology. When exposed to stress, mRNAs released after translational arrest condense with RNA binding proteins, resulting in the formation of membraneless RNA protein (RNP) condensates known as processing bodies (P-bodies) and stress granules (SGs). However, the impact of the assembly of these condensates on the biophysical properties of the crowded cytoplasmic environment remains unclear. Here, we find that upon exposure to stress, polysome collapse and condensation of mRNAs increases mesoscale particle diffusivity in the cytoplasm. Increased mesoscale diffusivity is required for the efficient formation of Q-bodies, membraneless organelles that coordinate degradation of misfolded peptides that accumulate during stress. Additionally, we demonstrate that polysome collapse and stress granule formation has a similar effect in mammalian cells, fluidizing the cytoplasm at the mesoscale. We find that synthetic, light-induced RNA condensation is sufficient to fluidize the cytoplasm, demonstrating a causal effect of RNA condensation. Together, our work reveals a new functional role for stress-induced translation inhibition and formation of RNP condensates in modulating the physical properties of the cytoplasm to effectively respond to stressful conditions.
The Type VI Secretion System of the Emerging PathogenStenotrophomonas maltophiliahas Antibacterial Properties
Authors: Crisan Cristian V. , Van Tyne Daria , Goldberg Joanna B. 
Published: May 2023

ABSTRACTAntagonistic behaviors between bacterial cells can have profound effects on microbial populations and disease outcomes. Polymicrobial interactions may be mediated by contact-dependent proteins with antibacterial properties. The Type VI Secretion System (T6SS) is a macromolecular weapon used by Gram-negative bacteria to translocate proteins into adjacent cells. The T6SS is used by pathogens to escape immune cells, eliminate commensal bacteria, and facilitate infection.Stenotrophomonas maltophiliais a Gram-negative opportunistic pathogen that causes a wide range of infections in immunocompromised patients and infects the lungs of patients with cystic fibrosis. Infections with the bacterium can be deadly and are challenging to treat because many isolates are multidrug-resistant. We found that globally dispersedS. maltophiliaclinical and environmental strains possess T6SS genes. We demonstrate that the T6SS of anS. maltophiliapatient isolate is active and can eliminate other bacteria. Furthermore, we provide evidence that the T6SS contributes to the competitive fitness ofS. maltophiliaagainst a co-infectingPseudomonas aeruginosaisolate, and that the T6SS alters the cellular organization ofS. maltophiliaandP. aeruginosaco-cultures. This study expands our knowledge of the mechanisms employed byS. maltophiliato secrete antibacterial proteins and compete against other bacteria.IMPORTANCEInfections with the opportunistic pathogenStenotrophomonas maltophiliacan be fatal for immunocompromised patients. The mechanisms used by the bacterium to compete against other prokaryotes are not well understood. We found that the T6SS allowsS. maltophiliato eliminate other bacteria and contributes to the competitive fitness against a co-infecting isolate. The presence of T6SS genes in isolates across the globe highlights the importance of this apparatus as a weapon in the antibacterial arsenal ofS. maltophilia. The T6SS may confer survival advantages toS. maltophiliaisolates in polymicrobial communities in both environmental settings and during infections.
Host subversion of bacterial metallophore usage drives copper intoxication
Authors: Hossain Saika , Morey Jacqueline R. , Neville Stephanie L. , Ganio Katherine , Radin Jana N. , Norambuena Javiera , Boyd Jeffrey M. , McDevitt Christopher A. , Kehl-Fie Thomas E. 
Published: May 2023

ABSTRACTMicroorganisms can acquire metal ions in metal-limited environments using small molecules called metallophores. While metals and their importers are essential, metals can also be toxic, and metallophores have limited ability to discriminate metals. The impact of the metallophore-mediated non-cognate metal uptake on bacterial metal homeostasis and pathogenesis remains to be defined. The globally significant pathogenStaphylococcus aureususes the Cnt system to secrete the metallophore staphylopine in zinc-limited host niches. Here, we show that staphylopine and the Cnt system facilitate bacterial copper uptake, potentiating the need for copper detoxification. Duringin vivoinfection, staphylopine usage increasedS. aureussusceptibility to host-mediated copper stress, indicating that the innate immune response can harness the antimicrobial potential of altered elemental abundances in host niches. Collectively, these observations show that while the broad-spectrum metal-chelating properties of metallophores can be advantageous, the host can exploit these properties to drive metal intoxication and mediate antibacterial control.IMPORTANCEDuring infection bacteria must overcome the dual threats of metal starvation and intoxication. This work reveals that the zinc-withholding response of the host sensitizesStaphylococcus aureusto copper intoxication. In response to zinc starvationS. aureusutilizes the metallophore staphylopine. The current work revealed that the host can leverage the promiscuity of staphylopine to intoxicateS. aureusduring infection. Significantly, staphylopine-like metallophores are produced by a wide range of pathogens, suggesting that this is a conserved weakness that the host can leverage to toxify invaders with copper. Moreover, it challenges the assumption that the broad-spectrum metal binding of metallophores is inherently beneficial to bacteria.
An open-source, high resolution, automated fluorescence microscope
Authors: Zehrer Ando C. , Martin-Villalba Ana , Diederich Benedict , Ewers Helge 
Published: May 2023

AbstractFluorescence microscopy is a fundamental tool in the life sciences, but the availability of sophisticated equipment required to yield high-quality, quantitative data is a major bottleneck in data production in many laboratories worldwide. This problem has long been recognized and the abundancy of low-cost electronics and the simplification of fabrication through 3D-printing have led to the emergence of open-source scientific hardware as a research field. Cost effective fluorescence microscopes can be assembled from cheaply mass-produced components, but lag behind commercial solutions in image quality. On the other hand, blueprints of sophisticated microscopes such as light-sheet or super-resolution systems, custom-assembled from high quality parts, are available, but require a high level of expertise from the user.Here we combine the UC2 microscopy toolbox with high-quality components and integrated electronics and software to assemble an automated high-resolution fluorescence microscope. Using this microscope, we demonstrate high resolution fluorescence imaging for fixed and live samples. When operated inside an incubator, long-term live-cell imaging over several days was possible. Our microscope reaches single molecule sensitivity, and we performed single particle tracking and SMLM super-resolution microscopy experiments in cells. Our setup costs a fraction of its commercially available counterparts but still provides a maximum of capabilities and image quality. We thus provide a proof of concept that high quality scientific data can be generated by lay users with a low-budget system and open-source software. Our system can be used for routine imaging in laboratories that do not have the means to acquire commercial systems and through its affordability can serve as teaching material to students.
Quantitative Determination of Protein Concentrations in Living Cells
Authors: Brinkenfeldt Nikolaj K. , Dias André , Moreno-Pescador Guillermo , Bendix Poul Martin , Martinez Karen L. 
Published: May 2023

AbstractBiological systems are regulated by molecular interactions which are tuned by the concentrations of each of the molecules involved. Cells exploit this feature by regulating protein expression, to adapt their responses to overstimulation. Correlating events in single cells to the concentrations of proteins involved can therefore provide important mechanistic insight into cell behavior. Unfortunately, quantification of molecular densities by fluorescence imaging becomes non-trivial due to the diffraction limited resolution of the imaged volume. We show here an alternative approach to overcome this limitation in optical quantification of protein concentrations which is based on calibrating protein volume and surface densities in a model membrane system. We exploit the ability of fluorescently labeled annexin V to bind membranes in presence of calcium. By encapsulating known concentrations of annexin V, we can directly infer the membrane density of annexin V after addition of Ca2+ and correlate the density with the measured fluorescence signal. Our method, named Calmet, enables quantitative determination of the concentration of cytosolic and membrane associated proteins. The applicability of Calmet is demonstrated by quantification of a transmembrane protein receptor (beta 1 adrenergic receptor) labeled by SNAP tagged fluorophores and expressed in HEK293 cells. Calmet is a generic method suitable for the determination of a broad range of concentrations and densities and can be used on regular fluorescence images captured by confocal laser scanning microscopy.
Formation of clathrin-pits and ATP-independent cholesterol-dependent tubules initiates mechano-regulation on de-adhesion
Authors: Mandal Tithi , Biswas Arikta , Ghosh Tanmoy , Manikandan Sreekanth , Kundu Avijit , Banerjee Ayan , Mitra Dhrubaditya , Sinha Bidisha 
Published: May 2023

AbstractAdherent cells ensure membrane homeostasis during de-adhesion by various mechanisms including endocytosis. Although mechano-chemical feedbacks involved in this process have been studied, the step-by-step build-up and resolution of the mechanical changes by endocytosis is not well understood. To investigate this, we study the de-adhesion of HeLa cells using a combination of interference reflection microscopy, optical-trapping and fluorescence experiments. We found that de-adhesion enhanced membrane height fluctuations of the basal membrane in the presence of an intact cortex. A reduction in the tether-force was also noted at the apical side. However, membrane fluctuations reveal phases of an initial drop in effective tension followed by a saturation. The area fractions of early (Rab5-labelled) and recycling (Rab4-labelled) endosomes as well as transferrin-labelled pits close to the basal plasma membrane also transiently increased. On blocking dynamin-dependent scission of endocytic pits, the regulation of fluctuations was not blocked but proceeded uncontrolled. Interestingly, the regulation could not be suppressed by ATP or cholesterol depletion individually but was arrested on depleting both. The data strongly supports pit-formation to be central to the reduction in fluctuations whether in normal or ATP depleted condition. Furthermore, while in normal conditions the contribution of clathrin-mediated endocytosis is clear, under ATP-depleted conditions we propose that cholesterol-dependent pits spontaneously regulate tension.SummaryWe show that during de-adhesion, cell edges retract, creating membrane folds and increasing fluctuations. Cells increase the rate of endocytosis to regulate back their membrane fluctuations. This is achieved by forming invaginations. Dynamin-dependent pathways are majorly involved, while cholesterol-dependent ATP-independent mechanisms also contribute.
The browser extension guidance for online information searching
Authors: Efendioğlu Esra , Sendurur Emine 
Published: May 2023

Purpose
This study aims to develop and test a browser extension as a scaffolding tool to guide learners about evaluating online sources.

Design/methodology/approach
In total, 129 undergraduate students participated in this experimental study. Both groups completed two Web searching tasks, but the experimental group used a browser extension.

Findings
The results indicated that there are significant differences between groups in terms of the number of accurate sources and visited sites. There were no differences neither in the success status nor the access time. The browser extension guidance affected certain search parameters, but this effect seemed to be diminished in accordance with students’ cognitive abilities as well as their digital literacy levels.

Research limitations/implications
The participants were from a vocational school, so any other study with different participants might reveal different findings.

Practical implications
The browser extension is convenient to be used with regards to interface and instructions. It can serve as a self-training tool with small changes in the code. The intervals and types of messages can be customized in line with the users’ needs.

Social implications
The approach used in this study can contribute to the dissemination of misleading information on the Web. People of any age can use and benefit from this approach via a simple extension.

Originality/value
The extension can serve as a fundamental framework for the construction of adaptive or smart extensions. As this study revealed the importance of both cognitive abilities and digital literacy levels, the extension can be enriched with the inclusion of cognitive scaffolding.
Customer influence on frontline employee work engagement
Authors: Yoo Jaewon , Chen Jing , Frankwick Gary L. 
Published: May 2023

PurposeThis study aims to employ conservation of resources (COR) theory to explain how customer support, customer power, customer orientation (CO) and product complexity impact frontline employees (FLEs) work engagement.Design/methodology/approachPartial least square structural equation modeling (PLS-SEM) was used to analyze data collected from 1,620 South Korean insurance salespeople using an on-line survey.FindingsResults show that customer support, customer power and CO will bring more FLEs work engagement, and product complexity negatively dilutes the work engagement gained from customer support.Practical implicationsThe results of this study suggest that firms should encourage FLEs to share their experiences and tactics in dealing with customer power and stimulate supportive customer behaviors. Since complex products, particularly financial products, require more explanation and information exchange for customers to understand them, managers might include simulations, videos and role-playing in training programs to show salespeople how to handle customers when attempting to sell these products.Originality/valueThis study investigates the effects of customer cognitive and emotional support on FLEs work engagement and also empirically demonstrates the positive effects of customer power.