bluuebunny/crossref_metadata_2025 huggingface dataset:
SPEEDS: A Portable Serological Testing Platform for Rapid Electrochemical Detection of SARS-CoV-2 Antibodies
Authors: Peng Ran , Pan Yueyue , Li Zhijie , Qin Zhen , Rini James M. , Liu Xinyu
Published: May 2021

The COVID-19 pandemic has resulted in a worldwide health crisis. Rapid diagnosis, new therapeutics and effective vaccines will all be required to stop the spread of COVID-19. Quantitative evaluation of serum antibody levels against the SARS-CoV-2 virus provides a means of monitoring a patient’s immune response to a natural viral infection or vaccination, as well as evidence of a prior infection. In this paper, a portable and low-cost electrochemical immunosensor is developed for the rapid and accurate quantification of SARS-CoV-2 serum antibodies. The immunosensor is capable of quantifying the concentrations of immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies against the SARS-CoV-2 spike protein in human serum. For IgG and IgM, it provides measurements in the range of 10.1 ng/mL − 60 µg/mL and 1.64 ng/mL − 50 µg/mL, respectively, and both antibodies can be assayed in 13 min. We also developed device stabilization and storage strategies to achieve stable performance of the immunosensor within 24-week storage at room temperature. We evaluated the performance of the immunosensor using COVID-19 patient serum samples collected at different time points after symptom onset. The rapid and sensitive detection of IgG and IgM provided by our immunosensor fulfills the need of rapid COVID-19 serology testing for both point-of-care diagnosis and population immunity screening.
Predisposing factors associated with the severity of the illness in adults with Covid-19 in Nepal
Authors: Jha Roshan Kumar , Shrestha Anil , Tamang Basant , K.C. Indu , Sah Shiv Kumar
Published: May 2021

Objective

We aimed to determine the prevalence of the severity of COVID-19 illness and its associated predisposing factors in Nepal.

Design

Cross-sectional, observational study

Setting

Single-centered hospital-based study, conducted at Nepal armed police force (APF) hospital, Kathmandu, Nepal.

Participants

All individuals aged ≥18 years with laboratory-confirmed SARS-Cov-2 (the SARS-CoV-2 specific real-time-RT-PCR result positive), regardless the severity of their disease.

Measurements

Disease severity was evaluated as a primary outcome and age, sex, BMI, smoking history, alcohol history, Hypertension, diabetes mellitus were evaluated as predictors in the analysis.

Results

Mean ages of the patients were 40.79±16.04 years, and about two-thirds of the patients were male 146 (73.7%). More than half 57.1% (95%CI: 52.42-61.51) of the population had a mild infection, whereas 16.7% (95%CI: 7.4-24.6%) had severe/critical illness. In univariate analysis, each 1-year increase in age (OR: 1.05; 95% CI:1.030-1.081; P<0.001), each 1 unit increase in BMI (OR:1.12; 95% CI:1.02-1.25; P=0.033), comorbid illness (OR: 5.79; 95%CI: 2.51-13.33; P<0.001), hypertension (OR:5.95; 95%CI:2.66-13.30: P<0.001), diabetes mellitus (OR:3.26; 95%CI:1.30-8.15: P<0.005), and fever (OR:34.64; 95% CI:7.98-150.38; P<0.001) were independently associated with severity of the disease, whereas age (OR: 1.049; 95% CI: 1.019-1.080; P=0.02), hypertension (OR: 4.77; 95%CI: 1.62-14.04; P=0.004), and fever (OR: 51.02; 95%CI: 9.56-272.51; P<0.001) remained a significant predictive factors in multivariate analysis.

Conclusion

The majority of the patients with COVID-19 had a mild illness, with 16.7% severe illness. Age, BMI, hypertension, diabetes mellitus, comorbidity, and temperature were associated the severity of the illness. Age, hypertension, and fever emerged as an independent predictive factors in multivariate analysis, and thus, these vulnerable groups should be given special protection to the infection and proactive intervention should be initiated at an early stage of the infection to diminish the severity of the illness and improve the clinical outcome of the disease.

Strengths and limitations of the study

Much of the studies on COVID-19 in Nepal focus on the describing epidemiology and clinical profile of the disease, however, risk factors that contribute to the severity of the illness are overlooked.

This study may help estimate the burden of the disease and identify the vulnerable group with poor prognosis, which is vital for clinicians and the public health approach to deal with the disease.

Although limiting the study to a single-center with a relatively small sample size, it, however, allows evaluation of the importance of the demographic and geographical variation.

Socio-economic factors, lifestyle, and availability of quality medical care may have contributed to the severity of the COVID-19, which needs to be addressed in a further large-scale study.
Indian Interventional trials for COVID-19 drugs: Insights and Learnings
Authors: Ranade Arati , Wani Kirtee , Premnath V. , Lele Chitra , Kale Smita
Published: May 2021

Since the COVID-19 pandemic began, India has substantially contributed to drug development and clinical research. Task Force on Repurposing of Drugs (TFORD) for COVID19 has tried to look at the overall position of India in terms of interventional clinical trials and highlight learnings which can prepare us to fight future pandemics in a better way. Trials registered on CTRI from March 2020 to December 2020 were considered for this purpose. From a total 409 trials registered, 108 focused on modern drugs. From 108 trials studied, 92 were randomized trials, 34 trials were sponsored by Indian Pharmaceutical industry, 23 were self-sponsored and 20 were sponsored by Research institutes and hospitals. Only 83 trials studied the repurposed drugs. An unfortunate revelation was that out of 108 trials, 79 showed as not yet recruiting. This highlights the urgent need for Government, Research institutions and Indian Pharmaceutical industries to break down silos and work together towards this common cause.
Genomic inference of a human super bottleneck in Mid-Pleistocene transition
Authors: Hu Wangjie , Hao Ziqian , Du Pengyuan , Di Vincenzo Fabio , Manzi Giorgio , Pan Yi-Hsuan , Li Haipeng
Published: May 2021

The demographic history is a foundation of human evolutionary studies. However, the ancient demographic history during the Mid-Pleistocene is poorly investigated while it is essential for understanding the early origin of humankind. Here we present the fast infinitesimal time coalescent (FitCoal) process, which allows the analytical calculation of the composite likelihood of a site frequency spectrum and provides the precise inference of demographic history. We apply it to analyze 3,154 present-day human genomic sequences. We find that African populations have passed through a population super bottleneck, a small effective size of approximately 1,280 breeding individuals between 930 and 813 thousand years ago. Further analyses confirm the existence of the super bottleneck on non-African populations although it cannot be directly inferred. This observation, together with simulation results, indicates that confounding factors, such as population structure and selection, are unlikely to affect the inference of the super bottleneck. The time interval of the super bottleneck coincides with a gap in the human fossil record in Africa and possibly marks the origin ofHomo heidelbergensis. Our results provide new insights into human evolution during the Mid-Pleistocene.
Broad neutralization against SARS-CoV-2 variants induced by a modified B.1.351 protein-based COVID-19 vaccine candidate
Authors: Su Danmei , Li Xinglin , He Cui , Huang Xueqing , Chen Meilin , Wang Qiang , Qin Wenchang , Liang Ying , Xu Rong , Wu Jinhua , Luo Peiwen , Yang Xiaofang , Zeng Yilan , Luo Mei , Luo Dongxia , Salisbury David M , Ambrosino Donna , Siber George , Clemens Ralf , Liang Peng , Liang Joshua G.
Published: May 2021

Beginning in late 2020, the emergence and spread of multiple variant SARS-CoV-2 strains harboring mutations which may enable immune escape necessitates the rapid evaluation of second generation COVID-19 vaccines, with the goal of inducing optimized immune responses that are broadly protective. Here we demonstrate in a mouse immunogenicity study that two doses of a modified B.1.351 spike (S)-Trimer vaccine (B.1.351 S-Trimer) candidate can induce strong humoral immune responses that can broadly neutralize both the original SARS-CoV-2 strain (Wuhan-Hu-1) and Variants of Concern (VOCs), including the UK variant (B.1.1.7), South African variant (B.1.351) and Brazil variant (P.1). Furthermore, while immunization with two doses (prime-boost) of Prototype S-Trimer vaccine (based on the original SARS-CoV-2 strain) induced lower levels of cross-reactive neutralization against the B.1.351 variant, a third dose (booster) administered with either Prototype S-Trimer or B.1.351 S-Trimer was able to increase neutralizing antibody titers against B.1.351 to levels comparable to neutralizing antibody titers against the original strain elicited by two doses of Prototype S-Trimer.
Serial interval of COVID-19 and the effect of Variant B.1.1.7: analyses from a prospective community cohort study (Virus Watch)
Authors: Geismar Cyril , Fragaszy Ellen , Nguyen Vincent , Fong Wing Lam Erica , Shrotri Madhumita , Beale Sarah , Rogers Alison , Lampos Vasileios , Byrne Thomas , Kovar Jana , Navaratnam Annalan M D , Patel Parth , Aldridge Robert W , Hayward Andrew
Published: May 2021

Introduction

Increased transmissibility of B.1.17 variant of concern (VOC) in the UK may explain its rapid emergence and global spread. We analysed data from putative household infector - infectee pairs in the Virus Watch Community cohort study to assess the serial interval of COVID-19 and whether this was affected by emergence of the B.1.17 variant.

Methods

The Virus Watch study is an online, prospective, community cohort study following up entire households in England and Wales during the COVID-19 pandemic. Putative household infector-infectee pairs were identified where more than one person in the household had a positive swab matched to an illness episode. Data on whether individual infections were caused by the B.1.1.7 variant were not available. We therefore developed a classification system based on the percentage of cases estimated to be due to B.1.17 in national surveillance data for different English regions and study weeks.

Results

Out of 24,887 illnesses reported, 915 tested positive for SARS-CoV-2 and 186 likely infector-infectee pairs in 186 households amongst 372 individuals were identified. The mean COVID-19 serial interval was 3.18 (95%CI: 2.55 - 3.81) days. There was no significant difference (p=0.267) between the mean serial interval for Variants of Concern (VOC) hotspots (mean = 3.64 days, (95%CI: 2.55 – 4.73)) days and non-VOC hotspots, (mean = 2.72 days, (95%CI: 1.48 – 3.96)).

Conclusions

Our estimates of the average serial interval of COVID-19 are broadly similar to estimates from previous studies and we find no evidence that B.1.1.7 is associated with a change in serial intervals. Alternative explanations such as increased viral load, longer period of viral shedding or improved receptor binding may instead explain the increased transmissibility and rapid spread and should undergo further investigation.
Mitigating the psychological impacts of COVID-19 restrictions: The Behavioural Activation in Social Isolation (BASIL) pilot randomised controlled trial to prevent depression and loneliness among older people with long term conditions
Authors: Gilbody Simon , Littlewood Elizabeth , McMillan Dean , Chew-Graham Carolyn A. , Bailey Della , Gascoyne Samantha , Sloan Claire , Burke Lauren , Coventry Peter , Crosland Suzanne , Fairhurst Caroline , Henry Andrew , Hewitt Catherine , Joshi Kalpita , Ryde Eloise , Shearsmith Leanne , Traviss-Turner Gemma , Woodhouse Rebecca , Clegg Andrew , Gentry Tom , Hill Andrew , Lovell Karina , Smith Sarah Dexter , Webster Judith , Ekers David
Published: May 2021

Background

Older adults with long-term conditions have become more socially isolated (often due to advice to ‘shield’ to protect them from COVID-19) and are thus at particular risk of depression and loneliness. There is a need for brief scalable psychosocial interventions to mitigate the psychological impacts of social isolation. Behavioural Activation is a plausible intervention, but a trial is needed.

Methods

We undertook an external randomised pilot trial (ISRCTN94091479) designed to test recruitment, retention and engagement with, and the acceptability and preliminary effects of the intervention. Participants aged ≥ 65 years with two or more long-term conditions were recruited between June and October 2020. Behavioural Activation was offered to intervention participants (n=47), and control participants received usual care (n=49).

Findings

Remote recruitment was possible and 45/47 (95.7%) randomised to the intervention completed one or more sessions (median 6 sessions). 90 (93.8%) completed the one month follow-up, and 86 (89.6%) completed the three month follow-up. The between-group comparison for the primary clinical outcome at one month was an adjusted between group mean difference of −0.50 PHQ-9 points (95% CI −2.01 to 1.01), but only a small number of participants had completed the intervention at this point. At three months, the PHQ-9 adjusted mean difference was 0.19 (95% CI −1.36 to 1.75). When we examined loneliness, the between-group difference in the De Jong Gierveld Loneliness scale at one month was 0.28 (95% CI −0.51 to 1.06), and there was statistically significant between group difference at three months (−0.87; 95% CI −1.56 to −0.18). Participants who withdrew had minimal depressive symptoms at entry.

Interpretation

Behavioural Activation is a plausible intervention to mitigate the psychological impacts of COVID-19 isolation for older adults. The intervention can be delivered remotely and at scale, but should be reserved for older adults with evidence of depressive symptoms. The significant reduction in loneliness is unlikely to be a chance finding, and this will now be confirmed in a fully powered RCT.

Funding

This study was funded by National Institute for Health Research (NIHR) Programme Grants for Applied Research (PGfAR) RP-PG-0217-20006
Deceleration of cell cycle underpins a switch from proliferative- to terminal division in plant stomatal lineage
Authors: Han Soon-Ki , Yang Jiyuan , Arakawa Machiko , Iwasaki Rie , Sakamoto Tomoaki , Kimura Seisuke , Kim Eun-Deok , Torii Keiko U.
Published: May 2021

Differentiation of specialized cell types from self-renewing progenitors requires precise cell cycle control. Plant stomata are generated through asymmetric divisions of a stem-cell-like precursor meristemoid followed by the single symmetric division that creates an adjustable pore surrounded by paired guard cells. The stomatal-lineage-specific transcription factor MUTE terminates the asymmetric divisions and triggers differentiation. However, the role of cell cycle machinery in this transition remains unknown. Through time-lapse imaging, we discover that the symmetric division is slower than the asymmetric division. We identify a plant-specific cyclin-dependent kinase inhibitor, SIAMESE-RELATED4 (SMR4), as a molecular brake that decelerates cell cycle during this transition. SMR4 is directly induced by MUTE and transiently accumulates in differentiating meristemoids. SMR4 physically and functionally associates with CYCD3;1 and extends G1-phase of asymmetric divisions. By contrast, SMR4 fails to interact with CYCD5;1, a MUTE-induced G1 cyclin, and permits the symmetric division. Our work unravels a molecular framework of the proliferation-to-differentiation switch within the stomatal lineage and suggests that a timely proliferative cell cycle is critical for the stomatal fate specification.
Development of a Low-Cost System for Simultaneous Longitudinal Biological Imaging
Authors: Ly Victoria T. , Baudin Pierre V. , Pansodtee Pattawong , Jung Erik A. , Voitiuk Kateryna , Rosen Yohei M. , Willsey Helen Rankin , Mantalas Gary L. , Seiler Spencer T. , Selberg John A. , Cordero Sergio A. , Ross Jayden M. , Rolandi Marco , Pollen Alex A. , Nowakowski Tomasz J. , Haussler David , Mostajo-Radji Mohammed A. , Salama Sofie R. , Teodorescu Mircea
Published: May 2021

Simultaneous longitudinal imaging across multiple conditions and replicates has been crucial for scientific studies aiming to understand biological processes and disease. Yet, imaging systems capable of accomplishing these tasks are economically unattainable for most academic and teaching laboratories around the world. Here we propose the Picroscope, which is the first low cost system for simultaneous longitudinal biological imaging made primarily using off-the-shelf and 3D-printed materials. The Picroscope is compatible with standard 24-well cell culture plates and captures 3D z-stack image data. The Picroscope can be controlled remotely, allowing for automatic imaging with minimal intervention from the investigator. Here we use this system in a range of applications. We gathered longitudinal whole organism image data for frogs, zebrafish and planaria worms. We also gathered image data inside an incubator to observe 2D monolayers and 3D mammalian tissue culture models. Using this tool, we can measure the behavior of entire organisms or individual cells over long time periods.
A quantitative map of nuclear pore assembly reveals two distinct mechanisms
Authors: Otsuka Shotaro , Tempkin Jeremy O. B. , Zhang Wanlu , Politi Antonio Z. , Rybina Arina , Hossain M. Julius , Kueblbeck Moritz , Callegari Andrea , Koch Birgit , Morero Natalia Rosalia , Sali Andrej , Ellenberg Jan
Published: May 2021

Understanding how the nuclear pore complex (NPC) assembles is of fundamental importance to grasp the mechanisms behind its essential function and understand its role during evolution of eukaryotes1–4. While at least two NPC assembly pathways exist, one during exit from mitosis and one during nuclear growth in interphase, we currently lack a quantitative map of the molecular assembly events. Here, we use fluorescence correlation spectroscopy (FCS) calibrated live imaging of endogenously fluorescently-tagged nucleoporins to map the changes in composition and stoichiometry of seven major modules of the human NPC during its assembly in single dividing cells. This systematic quantitative map reveals that the two assembly pathways employ strikingly different molecular mechanisms, inverting the order of addition of two large structural components, the central ring complex and nuclear filaments. The dynamic stoichiometry data underpinned integrative spatiotemporal modeling of the NPC assembly pathway, predicting the structures of postmitotic NPC assembly intermediates.
Drug-induced colorectal cancer persister cells show increased mutation rate
Authors: Russo Mariangela , Pompei Simone , Sogari Alberto , Corigliano Mattia , Crisafulli Giovanni , Bertotti Andrea , Gherardi Marco , Di Nicolantonio Federica , Bardelli Alberto , Lagomarsino Marco Cosentino
Published: May 2021

Compelling evidence shows that cancer persister cells limit the efficacy of targeted therapies. However, it is unclear whether persister cells are induced by anticancer drugs, and if their mutation rate quantitatively increases during treatment. Here, combining experimental characterization and mathematical modeling, we show that, in colorectal cancer, persisters are induced by drug treatment and show a 7- to 50-fold increase of mutation rate when exposed to clinically approved targeted therapies. These findings reveal that treatment may influence persistence and mutability in cancer cells and pinpoints new strategies to restrict tumor recurrence.
New strategy to select cross-reactivity Meningococci strains: immunization with Outer membrane vesicles of serogroup C and cationic lipid as adjuvant
Authors: Portilho Amanda Izeli , de Lima Gabriela Trzewikowski , De Gaspari Elizabeth
Published: May 2021

Background

Invasive meningococcal disease (IMD), caused by Neisseria meningitidis, is a public health problem, associated with high levels of morbidity and mortality, capable of causing outbreaks or epidemics, but preventable through vaccination. In Brazil, the main serogroups isolated are C and B. The last epidemic occurred in the ‘80s, in São Paulo, because of a B:4:P1.15 strain.

Methods

Adult Swiss mice were immunized with outer membrane vesicles (OMV) of N. meningitidis strain C:4:P1.15, adjuvanted by the cationic lipid dioctadecyldimethylammonium bromide in bilayer fragments (DDA-BF), administered via prime-booster (intranasal/subcutaneous) scheme. The humoral response was accessed by Immunoblotting and ELISA, using homologous immunization strain and a different serogroup but equal serosubtype strain, N. meningitidis B:4:P1.15.

Results

Immunoblotting revealed the recognition of antigens associated with the molecular weight of Porin A and Opacity proteins, which are immunogenic but highly heterogeneous, and Tbp and NspA, which are more homogeneous between meningococci strains. ELISA results showed antibody production that persisted after 190 days and recognized the C:4:P1.15 and the B:4:P1.15 strains, with high avidity index. The adjuvanted group recognized antigens following the IN prime and had a higher avidity index against the heterologous strain.

Conclusions

DDA-BF improved the humoral response, but the OMV alone induced high avidity index antibodies as well. Even though these are preliminary results, we see it as a promising approach for affordable meningococcal immunization in developing countries, at outbreak or epidemic situations.
Modeling the stepwise extension of recombination suppression on sex chromosomes and other supergenes through deleterious mutation sheltering
Authors: Jay Paul , Tezenas Emilie , Véber Amandine , Giraud Tatiana
Published: May 2021

Many organisms have sex chromosomes with large non-recombining regions that have expanded stepwise, generating “evolutionary strata” of differentiation. The reasons for this remain poorly understood, but the principal hypotheses proposed to date are based on antagonistic selection due to differences between sexes. However, it has proved difficult to obtain empirical evidence of a role for sexually antagonistic selection in extending recombination suppression, and antagonistic selection has been shown to be unlikely to account for the evolutionary strata observed on fungal mating-type chromosomes. There may, therefore, be other mechanisms involved in the extension of non-recombining regions. We show here, by mathematical modeling and stochastic simulation, that recombination suppression on sex chromosomes and around supergenes can expand in a stepwise manner under a wide range of parameter values simply because it shelters recessive deleterious mutations, which are ubiquitous in genomes. Permanently heterozygous alleles, such as the maledetermining allele in XY systems, protect linked chromosomal inversions against the expression of their recessive mutation load, leading to the successive accumulation of inversions around these alleles without the need for antagonistic selection. Similar results were obtained with models assuming recombination-suppressing mechanisms other than chromosomal inversions, and for supergenes other than sex chromosomes, including those without XY-like asymmetry, such as fungal mating-type chromosomes. However, inversions capturing a permanently heterozygous allele were found to be less likely to spread when the mutation load was lower (e.g. under conditions of large effective population size, low mutation rates and high dominance coefficients). This may explain why sex chromosomes remain homomorphic in some organisms but are highly divergent in others. Here, we explicitly state and model a simple and testable hypothesis explaining the existence of stepwise extensions of recombination suppression on sex chromosomes, which can also be applied to mating-type chromosomes and supergenes in general.
Synaptic Plasticity in the Agranular Insular Cortex Predicts Escalated Ethanol Consumption
Authors: Shillinglaw Joel E. , Aziz Heather C. , Carrizales Daniela G. , Morrisett Richard A. , Mangieri Regina A.
Published: May 2021

The Agranular Insular Cortex (AIC) is implicated in alcohol use disorder and pharmacologically relevant concentrations of acute ethanol inhibit N-methyl-D-aspartate receptor (NMDAR)-mediated glutamatergic synaptic transmission and plasticity onto layer 2/3 AIC pyramidal neurons. However, it is not known whether the actions of ethanol on glutamatergic synapses are means by which chronic ethanol alters mechanisms of learning and memory in AIC as alcohol drinking transitions from controlled to problematic. We utilized the chronic intermittent ethanol (CIE) vapor model of ethanol exposure in adult male mice, alone or in combination with voluntary ethanol consumption, to determine whether glutamatergic synapses on layer 2/3 AIC pyramidal neurons are differentially regulated by different durations and intensities of chronic ethanol exposure. We observed evidence of both ethanol- and age-related metaplasticity of AIC layer 2/3 glutamatergic synapses, as only young adult, ethanol-naïve mice exhibited NMDAR-dependent long term depression ex vivo. Our findings also indicated that voluntary ethanol consumption alone can elicit glutamatergic plasticity in vivo. We found that the ratio of NMDAR- to AMPAR-mediated postsynaptic currents was reduced not only in CIE-treated, but also in air-treated, chronically drinking mice relative to ethanol-naïve controls. Furthermore, lower NMDA/AMPA ratios were predictive of greater escalation of ethanol consumption. These findings suggest that even moderate exposure to ethanol may elicit plasticity in the agranular insular cortex that contributes to the progression toward uncontrolled drinking.
Nicotinic acetylcholine receptor partial antagonist polyamides from tunicates and their predatory sea slugs
Authors: Paguigan Noemi D. , Tun Jortan O. , Leavitt Lee S. , Lin Zhenjian , Chase Kevin , Dowell Cheryl , Deering-Rice Cassandra E. , Lim Albebson L. , Karthikeyan Manju , Hughen Ronald W. , Zhang Jie , Peterson Randall T. , Reilly Christopher A. , Light Alan R. , Raghuraman Shrinivasan , McIntosh J. Michael , Olivera Baldomero M. , Schmidt Eric W.
Published: May 2021

In our efforts to discover new drugs to treat pain, we identified molleamines A-E (1-5) as major neuroactive components of the sea slug, Pleurobranchus forskalii and their prey, Didemnum molle tunicates. The chemical structures of molleamines were elucidated by spectroscopy and confirmed by the total synthesis of molleamines A (1) and C (3). Synthetic 3 completely blocked acetylcholine-induced calcium flux in peptidergic nociceptors (PNs) in the somatosensory nervous system. Compound 3 affected neither the α7 nAChR nor the muscarinic acetylcholine receptors in calcium flux assays. In addition to nociceptors, 3 partially blocked the acetylcholine-induced calcium flux in the sympathetic nervous system, including neurons from the superior cervical ganglion. Electrophysiology revealed a block of α3β4 (mouse) and α6/α3β4 (rat) nicotinic acetylcholine receptors (nAChRs), with IC50 values of 1.4 and 3.1 µM, respectively. Molleamine C (3) is a partial antagonist, reaching a maximum block of 76-82% of the acetylcholine signal and showing no partial agonist response. Molleamine C (3) may thus provide a lead compound for the development of neuroactive compounds with unique biological properties.
Basal Ganglia Responses to Electrical Stimulation of the Posterior Hypothalamic Nucleus
Authors: Young Calvin K. , Bland Brian H.
Published: May 2021

Electrical or chemical stimulation of the posterior hypothalamic nucleus (PH) elicits highly adaptive locomotion, demonstrating both evidence of flexibility and variety in exhibited motor behaviours. However, the neural substrates of PH stimulation elicited behavioural changes are poorly understood. The basal ganglia are postulated to be critically involved in the process of action selection in conjunction with thalamo-cortical systems. The present study examines changes in basal ganglia activities in response to the high-frequency stimulation of the PH. Under urethane anaesthesia, ensemble and single-unit recordings were obtained from the striatum (STR), globus pallidus externa (GPe), entopeduncular nucleus (EP), subthalamic nucleus (STN) and the substantia nigra pars reticulata (SNr). Upon PH stimulation, increases in firing rates were observed in the STR, GPe, and STN, a decrease was observed in the SNr and no changes were seen in the EP. The increase in spike rate in the STR and GPe was dependent on the stimulation intensity but not duration. Despite the differences in the direction of firing changes during PH stimulation, all examined areas including those not part of the basal ganglia demonstrated an elevated spiking rate upon stimulus train termination. Taking into account the known anatomical connections between the PH and the basal ganglia, it is hypothesized responses seen during PH stimulus trains are mediated through thalamic and cortical relays whereas the overall post-stimulus excitatory response is related to the impact of the PH on brainstem arousal systems.
Polarized Dishevelled dissolution and condensation drives embryonic axis specification in oocytes
Authors: Swartz S. Zachary , Tan Tzer Han , Perillo Margherita , Fakhri Nikta , Wessel Gary M. , Wikramanayake Athula H. , Cheeseman Iain M.
Published: May 2021

The organismal body axes that are formed during embryogenesis are intimately linked to intrinsic asymmetries established at the cellular scale in oocytes [1]. Here, we report an axis-defining event in meiotic oocytes of the sea star Patiria miniata. Dishevelled is a cytoplasmic Wnt pathway effector required for axis development in diverse species [2-4], but the mechanisms governing its function and distribution remain poorly defined. Using time-lapse imaging, we find that Dishevelled localizes uniformly to puncta throughout the cell cortex in Prophase I-arrested oocytes, but becomes enriched at the vegetal pole following meiotic resumption through a dissolution-condensation mechanism. This process is driven by an initial disassembly phase of Dvl puncta, followed by selective reformation of Dvl assemblies at the vegetal pole. Rather than being driven by Wnt signaling, this localization behavior is coupled to meiotic cell cycle progression and influenced by Lamp1+ endosome association and Frizzled receptors pre-localized within the oocyte cortex. Our results reveal a cell cycle-linked mechanism by which maternal cellular polarity is transduced to the embryo through spatially-regulated Dishevelled dynamics.
Differential surface competition and biofilm invasion strategies of Pseudomonas aeruginosa PA14 and PA01
Authors: Katharios-Lanwermeyer Stefan , Kassety Swetha , Nadell Carey D. , O’Toole George A.
Published: May 2021

Pseudomonas aeruginosa strains PA14 and PAO1 are among the two best characterized model organisms used to study the mechanisms of biofilm formation, while also representing two distinct lineages of P. aeruginosa. Our previous work showed that P. aeruginosa PA14 and PAO1 use distinct strategies to initiate biofilm growth. Using differentially-labeled strains and microfluidic devices, we show that PAO1 can outcompete PA14 in a head-to-head competition during early colonization of a surface, can do so in constant and perturbed environments, that this advantage is specific to biofilm growth and requires production of the Psl polysaccharide. In contrast, the P. aeruginosa PA14 exhibits a competitive fitness advantage when invading a pre-formed biofilm and is better able to tolerate starvation than PAO1 in the biofilm context. These data support the model that while P. aeruginosa PAO1 and PA14 are both able to effectively colonize surfaces, these strains use distinct strategies that are advantageous under different environmental settings.

Importance

Recent studies indicate that P. aeruginosa PAO1 and PA14 use distinct strategies to initiate biofilm formation, with PAO1 committing to the surface through a processive mode of attachment, while PA14 uses a non-processive surface engagement strategy. We investigated whether their respective colonization strategies impact their ability to effectively compete under different biofilm-forming regimes. Our work shows that these different strategies do indeed impact how these strains colonize the surface: PAO1 dominates during colonization of a naïve surface, while PA14 is more effective in colonizing a pre-formed biofilm or withstanding starvation conditions. These data suggest that even for very similar microbes there may be distinct strategies to successfully colonize and persist on surfaces during the biofilm life cycle.
Biochemical Barriers on the Path to Ocean Anoxia?
Authors: Giovannoni Stephen , Chan Francis , Davis Edward , Deutsch Curtis , Wolf Sarah
Published: May 2021

The kinetics of microbial respiration suggest that, if excess organic matter is present, oxygen should fall to nanomolar levels, in the range of the Michaelis-Menten constants (Km). Yet even in many biologically productive coastal regions, lowest observed O2 concentrations often remain several orders of magnitude higher than respiratory Km values. We propose the Hypoxic Barrier Hypothesis (HBH) to explain this apparent discrepancy. The HBH postulates that oxidative enzymes involved in organic matter catabolism are kinetically limited by O2 at concentrations far higher than the thresholds for respiration. We found support for the HBH in a meta-analysis of 1137 O2 Km values reported in the literature: the median value for terminal respiratory oxidases was 350 nM, but for other oxidase types the median value was 67 μM. The HBH directs our attention to the kinetic properties of an important class of oxygen-dependent reactions that could help explain the trajectories of ocean ecosystems experiencing O2 stress.

IMPORTANCE

Declining ocean oxygen associated with global warming and climate change is impacting marine ecosystems across scales from microscopic planktonic communities to global fisheries. We report a fundamental dichotomy in the affinity of enzymes for oxygen. The importance of this observation has yet to be fully assessed, but it is predicted to impact the rate at which organic matter is oxidized in hypoxic ecosystems, and the types of organic matter that accumulate. Competition between intracellular enzymes for oxygen may also have impacted microbial strategies of adaptation to suboxia.
In Silico Molecular-Based Rationale for SARS-CoV-2 Spike Circulating Mutations Able to Escape Bamlanivimab and Etesevimab Monoclonal Antibodies
Authors: Laurini Erik , Marson Domenico , Aulic Suzana , Fermeglia Alice , Pricl Sabrina
Published: May 2021

The purpose of this work was to provide an in silico molecular rationale of the role eventually played by currently circulating S-RBDCoV-2 mutations in evading the immune surveillance effects elicited by the two Eli Lilly LY-CoV555/bamlanivimab and LY-CoV016/etesevimab monoclonal antibodies. The main findings from this study and shows that, compared to the wild-type SARS-CoV-2 spike protein, mutations E484A/G/K/Q/R/V, Q493K/L/R, S494A/P/R, L452R and F490S are predicted to be markedly resistant to neutralization by LY-CoV555, while mutations K417E/N/T, D420A/G/N, N460I/K/S/T, T415P, and Y489C/S are predicted to confer LY-CoV016 escaping advantage to the viral protein. A challenge of our global in silico results against the relevant experimental data resulted in an overall 90% agreement. This achievement not only constitutes a further, robust validation of our computer-based approach but also yields a molecular-based rationale for all relative experimental findings, and leads us to conclude that the current circulating SARS-CoV-2 and all possible emergent variants carrying these mutations in the spike protein can present new challenges for mAb-based therapies and ultimately threaten the fully-protective efficacy of currently available vaccines.
Rules for designing protein fold switches and their implications for the folding code
Authors: Chen Yingwei , He Yanan , Ruan Biao , Choi Eun Jung , Chen Yihong , Motabar Dana , Solomon Tsega , Simmerman Richard , Kauffman Thomas , Gallagher D. Travis , Orban John , Bryan Philip N.
Published: May 2021

We have engineered switches between the three most common small folds, 3α, 4β+α, and α/β−plait, referred to here as A, B, and S, respectively. Mutations were introduced into the natural S protein until sequences were created that have a stable S-fold in their longer (∼90 amino acid) form and have an alternative fold (either A or B) in their shorter (56 amino acid) form. Five sequence pairs were designed and key structures were determined using NMR spectroscopy. Each protein pair is 100% identical in the 56 amino acid region of overlap. Several rules for engineering switches emerged. First, designing one sequence with good native state interactions in two folds requires care but is feasible. Once this condition is met, fold populations are determined by the stability of the embedded A- or B-fold relative to the S-fold and the conformational propensities of the ends that are generated in the switch to the embedded fold. If the stabilities of the embedded fold and the longer fold are similar, conformation is highly sensitive to mutation so that even a single amino acid substitution can radically shift the population to the alternative fold. The results provide insight into why dimorphic sequences can be engineered and sometimes exist in nature, while most natural protein sequences populate single folds. Proteins may evolve toward unique folds because dimorphic sequences generate interactions that destabilize and can produce aberrant functions. Thus, two-state behavior may result from nature’s negative design rather than being an inherent property of the folding code.

Significance Statement

We establish general rules for designing protein fold switches by engineering dimorphic sequences that link the three most common small folds. The fact that switches can be engineered in arbitrary and common protein folds, sheds light on several important questions: 1) What is the generality of fold switching? 2) What types of folds are amenable to switching? 3) What properties are shared by sequences that can fold into two completely different structures? This work has implications for understanding how amino acid sequence encodes structure, how proteins evolve, how mutation is related to disease, and how function is annotated to sequences of unknown structure.

Classification

Biological Sciences: Biochemistry; Physical Sciences: Biophysics and Computational Biology
Effects of common mutations in the SARS-CoV-2 Spike RBD domain and its ligand the human ACE2 receptor on binding affinity and kinetics
Authors: Barton Michael I. , MacGowan Stuart , Kutuzov Mikhail , Dushek Omer , Barton Geoffrey J. , van der Merwe P. Anton
Published: May 2021

The interaction between the SARS-CoV-2 virus Spike protein receptor binding domain (RBD) and the ACE2 cell surface protein is required for viral infection of cells. Mutations in the RBD domain are present in SARS-CoV-2 variants of concern that have emerged independently worldwide. For example, the more transmissible B.1.1.7 lineage has a mutation (N501Y) in its Spike RBD domain that enhances binding to ACE2. There are also ACE2 alleles in humans with mutations in the RBD binding site. Here we perform a detailed affinity and kinetics analysis of the effect of five common RBD mutations (K417N, K417T, N501Y, E484K and S477N) and two common ACE2 mutations (S19P and K26R) on the RBD/ACE2 interaction. We analysed the effects of individual RBD mutations, and combinations found in new SARS-CoV-2 variants first identified in the UK (B.1.1.7), South Africa (B.1.351) and Brazil (P1). Most of these mutations increased the affinity of the RBD/ACE2 interaction. The exceptions were mutations K417N/T, which decreased the affinity. Taken together with other studies, our results suggest that the N501Y and S477N mutations primarily enhance transmission, the K417N/T mutations facilitate immune escape, and the E484K mutation facilitates both transmission and immune escape.
Expectation of being affected: an enactive perspective of spectators' expectations of contemporary dance
Authors: Moisio Saara
Published: May 2021

Purpose

This article examines how spectators describe their expectations of contemporary dance by referring to action. Through discussing a qualitative audience study, the article argues that spectators always have an expectation of being affected by performances they attend. This expectation can guide their interest in attending performances of certain genres instead of other possible ones on offer. Additionally, the article points out how spectators can actively manage their expectations in order to be affected.

Design/methodology/approach

The study is based on 21 in-depth interviews with spectators at a dance venue, a company and a festival in Finland. The analysis of the interviews combines thematic analysis with metaphor analysis. Employing the paradigm of enaction and the concept of affordances, this article approaches expectations as embodied and dynamic, created in interactions between artists, producers and spectators.

Findings

The analysis shows that when speaking about their expectations of performances, spectators use bodily and spatial metaphors. Focusing on metaphors reveals how, for the spectators, performances afford a possibility for action that affects them. The interviewed spectators describe that contemporary dance is “not set in its ways”, and therefore it keeps them “awake” and their thoughts do “not fossilize”. This way, they understand contemporary dance as a genre that affords a possibility to be affected by allowing a freedom of own interpretation and surprising experiences if they desire such.

Originality/value

Concentration on the metaphors of language offers a deeper understanding of the active nature of spectators' expectations. Understanding how spectators describe their expectations by referring to action that enables the shaping of their emotions and thoughts can help the development of arts marketing and audience engagement.
Seeing the invisible: brand authenticity and the cultural production of queer imagination
Authors: Södergren Jonatan , Vallström Niklas
Published: May 2021

Purpose

The twofold aim of this theory-building article is to raise questions about the ability of queer cinema to transform market culture and ideologies around gender and sexuality. First, the authors examine how the very capitalization of queer signifiers may compromise the dominant order from within. Second, the authors address how brands possibly can draw on these signifiers to project authenticity.

Design/methodology/approach

Through visual methods of film criticism and the semiotic analysis of three films (Moonlight, Call Me By Your Name and Portrait of a Lady on Fire), the authors outline some profound narrative tensions addressed by movie makers seeking to give an authentic voice to queer lives.

Findings

Brands can tap into these narrative attempts at “seeing the invisible” to signify authenticity. False sublation, i.e. the “catch-22” of commodifying the queer imaginaries one seeks to represent, follows from a Marcusean analysis.

Practical implications

In more practical terms, “seeing the invisible” is proposed as a cultural branding technique. To be felicitous, one has to circumvent three narrative traditions: pathologization, rationalization and trivialization.

Originality/value

In contrast to Marcuse's pessimist view emphasizing its affirmative aspects, the authors conclude that such commodification in the long term may have transformative effects on the dominant ideology. This is because even if something is banished to the realm of imagination, e.g. through aesthetic semblance, it can still be enacted in real life.
Challenging the context: mumpreneurship, copreneurship and sustainable thinking in the entrepreneurial process of women – a case study in Ecuador
Authors: Chávez Rivera María Eulalia , Fuentes Fuentes María del Mar , Ruiz-Jiménez Jenny María
Published: May 2021

Purpose

The purpose of this article is to determine the factors in the context of entrepreneurship that are evident in Ecuador, a country that has the highest rate of female entrepreneurship worldwide with 34% according to the Global Entrepreneurship Monitor (GEM) (2019).

Design/methodology/approach

A qualitative study was carried out with 39 cases, applying in-depth personal interviews and focus groups to selected cases in the main cities of Ecuador.

Findings

The results suggest that “mumpreneurship”, copreneurship and sustainable thinking arise in response to the environment. Deepening then in the perspective of the 5M proposes by Brushet al. (2009) that give us a framework of the macroenvironment of women entrepreneurship and offers a holistic understanding of women's entrepreneurship, adding a sixth “M” which is “Environmental Thinking” or the environmental thinking that is present in the current context.

Originality/value

This article is one of the first to analyse the context of female entrepreneurship in Ecuador and determine the context factors that influence the identification of opportunities and the exploitation of entrepreneurial opportunities. It also presents the expectations and challenges of the women who shape the authors’ case studies and give voice to Ecuadorian women. Consequently, this research will support the configuration of policies that supports each of the stages of women's entrepreneurial processes.
Improvement of a topological level-set approach to find optimal topology by considering body forces
Authors: Takalloozadeh Meisam , Yoon Gil Ho
Published: May 2021

Purpose

Body forces are always applied to structures in the form of the weight of materials. In some cases, they can be neglected in comparison with other applied forces. Nevertheless, there is a wide range of structures in civil and mechanical engineering in which weight or other types of body forces are the main portions of the applied loads. The optimal topology of these structures is investigated in this study.

Design/methodology/approach

Topology optimization plays an increasingly important role in structural design. In this study, the topological derivative under body forces is used in a level-set-based topology optimization method. Instability during the optimization process is addressed, and a heuristic solution is proposed to overcome the challenge. Moreover, body forces in combination with thermal loading are investigated in this study.

Findings

Body forces are design-dependent loads that usually add complexity to the optimization process. Some problems have already been addressed in density-based topology optimization methods. In the present study, the body forces in a topological level-set approach are investigated. This paper finds that the used topological derivative is a flat field that causes some instabilities in the optimization process. The main novelty of this study is a technique used to overcome this challenge by using a weighted combination.

Originality/value

There is a lack of studies on level-set approaches that account for design-dependent body forces and the proposed method helps to understand the challenges posed in such methods. A powerful level-set-based approach is used for this purpose. Several examples are provided to illustrate the efficiency of this method. Moreover, the results show the effect of body forces and thermal loading on the optimal layout of the structures.