bluuebunny/crossref_metadata_2025 huggingface dataset:
Stroke impairs the proactive control of dynamic balance during predictable treadmill accelerations
Authors: Cornwell Tara , Finley James M.
Published: October 2024

We maintain balance during gait using both proactive and reactive control strategies. Damage to the brain from a stroke impairs reactive balance, but little is known about how a stroke impacts proactive control during walking. Identifying stroke-related impairments to proactive control could inform the design of interventions to improve balance and reduce fall risk. Therefore, we determined if people with and without stroke differ in their ability to use proactive strategies during predictable treadmill accelerations. Groups of 14 adults with and without stroke walked with single-belt accelerations at random (every one to five strides) and regular (every three strides) intervals. We quantified the effects of the perturbations as changes to center of mass (COM) speed and used mechanical leg work to quantify the proactive strategies to slow the COM. Participants without stroke reduced peak COM speed better than those with stroke when perturbations were at regular intervals (-0.023 versus -0.001 m/s; p=0.007). They also reduced positive leg work more during the perturbation step than the group post-stroke (-7.7% versus - 1.9%; p=0.004). Together, these results demonstrate that the sensorimotor impairments resulting from a stroke impair the ability to generate effective proactive adjustments to reduce the destabilizing effects of predictable perturbations.
inTRACKtive — A Web-Based Tool for Interactive Cell Tracking Visualization
Authors: Huijben Teun A.P.M. , Anderson Ashley G. , Sweet Andrew , Hoops Erin , Larsen Connor , Awayan Kyle , Bragantini Jordão , Chiu Chi-Li , Royer Loïc A.
Published: October 2024

We introduce inTRACKtive, an innovative web-based tool for interactive visualization and sharing of large 3D cell tracking datasets, eliminating the need for software installations or data downloads. Built with modern web technologies, inTRACKtive enables researchers to explore cell-tracking results from terabyte-scale microscopy data, conduct virtual fate-mapping experiments, and share these results via simple hyperlinks. The platform powers the Virtual Embryo Zoo, an online resource showcasing cell tracking datasets from state-of-the-art light-sheet embryonic microscopy of six model organisms. inTRACKtive’s open-source code allows users to visualize their own data or host customized viewer instances. By providing easy access to complex tracking datasets, inTRACKtive offers a versatile, interactive, collaborative tool for developmental biology.
Regulating biocondensates within synthetic cells via segregative phase separation
Authors: Chen Chang , Love Caroline M. , Carnahan Christopher F. , Ganar Ketan A. , Parikh Atul N. , Deshpande Siddharth
Published: October 2024

Living cells orchestrate a myriad of biological reactions within a highly complex and crowded environment. A major factor responsible for such seamless assembly are the preferential interactions between the constituent macromolecules, either associative or segregative, that can drive de-mixing to produce co-existing phases, and thus provide a dynamic intracellular compartmentalization. But how these two types of interactions, occurring simultaneously within the cytoplasmic space, influence each other is still largely unknown. This makes understanding and applying the molecular interactions that interfere with each other in such crowded environments crucial when engineering increasingly complex synthetic cells. Here, we show that the interplay between segregative and associative phase separation within cell-mimicking vesicles can lead to rich dynamics between them. Using on-chip microfluidic systems, we encapsulate the associative and segregative components in cell-sized containers and trigger their phase separations to create hierarchical structures that act as molecular recruiters, membrane targeting agents, and initiators of condensation. The obtained multiphase architecture provides an isolated microenvironment for condensates, restricting their molecular communication as well as diffusive motion, and leading to budding-like behaviour at the lipid membrane. In conclusion, we propose segregative phase separation as a universal condensate regulation strategy in managing molecular distribution, condensate location, as well as membrane interaction. We believe our approach will facilitate controlling the behaviour of membraneless organelles within synthetic cells.
Chromosomal-level reference genome and microRNAs of the ricefield flatsedgeCyperus iria
Authors: Tsang Stacey S.K. , Nong Wenyan , Law Sean T.S. , Bede Jacqueline C. , Chen Shan-Shan , Li Sa , Xie Yichun , Swale Thomas , Zhao Yiqiang , Lau David T.W. , Kai Zhen-peng , Chan Ting Fung , Tobe Stephen S. , Bendena William G. , Hui Jerome H.L.
Published: October 2024

Background

Grass-like plants in the Cyperaceae family, commonly known as sedges, have a global distribution and include many economically problematic weeds. The ricefield flatsedge,Cyperus iria, is an aggressive weed in rice crops in Asia.

Result

Here, we present a chromosomal-level genome assembly forC. iria(461.2 Mb, scaffold N50 = 7.3 Mbp, 99.6% BUSCO score) providing potential targets for the control of this devastating weed. Based on the genome assembly and transcriptomes of vegetative tissues, 52,574 protein-coding genes were predicted to be encoded. A total of 26 conserved and 75 novel microRNAs, including 9 microRNA clusters, were also annotated. Synteny and microRNA cluster analyses further showed thatC. iriahad undergone at least one round of whole genome duplication.

Conclusion

The genomic resource established in this study sets up a foundation to further address basic and applied questions in the Cyperaceae.
Highly enhanced transgene integration in human pluripotent stem cells by serine integrase BxbI
Authors: Autio Matias I. , Perrin Arnaud
Published: October 2024

Genome engineering and especially integration of large DNA payloads in human pluripotent stem cells (hPSC) remains challenging largely due to the sensitive nature of hPSCs. Site specific recombinases such as the serine integrase Bxb1 have been utilised successfully to target hPSC, however the targeting efficiencies remain low. Here we leveraged codon optimisation, inclusion of a nuclear localisation signal, mRNA modality and co-introduction of p53 dominant negative fragment to increase the transgene payload integration efficiency by up to 20-fold in defined genomic safe harbours in hPSCs.
Intrahost dynamics, together with genetic and phenotypic effects predict the success of viral mutations
Authors: Tan Cedric C.S. , Escalera-Zamudio Marina , Yavlinsky Alexei , van Dorp Lucy
Published: October 2024

Predicting the fitness of mutations in the evolution of pathogens is a long-standing and important, yet largely unsolved problem. In this study, we used SARS-CoV-2 as a model system to explore whether the intrahost diversity of viral infections could provide clues on the relative fitness of single amino acid variants (SAVs). To do so, we analysed ~15 million complete genomes and nearly ~8000 sequencing libraries generated from SARS-CoV-2 infections, which were collected at various timepoints during the COVID-19 pandemic. Across timepoints, we found that many successful SAVs were detected in the intrahost diversity of samples collected prior, with a median of 6-40 months between the initial collection dates of samples and the highest frequency seen for these SAVs. Additionally, we found that the co-occurrence of intrahost SAVs significantly captures genetic linkage patterns observed at the interhost level (Pearson's r=0.28-0.45, all p<0.0001). Further, we show that machine learning models can learn highly generalisable intrahost, physiochemical and phenotypic patterns to forecast the future fitness of intrahost SAVs (r2=0.48-0.63). Most of these models performed significantly better when considering genetic linkage (r2=0.53-0.68). Overall, our results document the evolutionary forces shaping the fitness of mutations, which may offer potential to forecast the emergence of future variants and ultimately inform the design of vaccine targets.
Stability vs flexibility: reshaping archaeal membranes in silico
Authors: Amaral Miguel , Frey Felix , Jiang Xiuyun , Baum Buzz , Šarić Anđela
Published: October 2024

Across the tree of life, distinct designs of cellular membranes have evolved. In bacteria and eukaryotes single-headed lipids self-assemble into flexible bilayer membranes. By contrast, archaea often possess double-headed, monolayer spanning bolalipids, mixed with bilayer lipids, enabling them to survive in harsh environments. Here, using a minimal computational model for bolalipid membranes, we discover trade-offs when forming membranes. We find that membranes made out of flexible bolalipids resemble bilayer membranes as bolalipids exhibit conformational switch into U-shaped conformations to enable higher curvatures. Conversely, stiffer bolalipids, resembling those in extremophile archaea, take on straight conformations and form liquid membranes that are stiff, and prone to pore formation during membrane reshaping. Strikingly, we show how to achieve fluid bolalipid membranes that are both stable and flexible – by including small amounts of bilayer lipids, as archaea do. Our study explains how different organisms resolve trade-offs when generating membranes of desired material properties.
Androgen receptor modulation of vocal circuitry in Alston’s singing mouse
Authors: Zheng Da-Jiang , Mardis Britt , Lam Denise , Islam Tarik , Tripp Joel , Phelps Steven
Published: October 2024

Animal courtship and aggressive displays are dramatic, often sexually dimorphic behaviors that require the coordinated modulation of diverse motivational and motor circuits. In Alston’s singing mice, a novel and elaborate advertisement vocalization is sexually dimorphic and steroid sensitive (Scotinomys teguina). Males sing more often than females, and on average male songs have more notes. Song is influenced by circulating androgens, but how such hormonal differences influence the diverse brain regions involved in vocal display is not understood. To characterize androgen-sensitive sites in the vocal motor pathway, we used two isoforms of pseudorabies virus (PRV) to double-label circuits ending in laryngeal and jaw muscles involved in vocalization, and co-labeled these neurons for androgen receptor (AR). Next we manipulated circulating androgens and observed the effects on AR distribution and male song. We find androgens drive coordinated changes in AR abundance across motor and motivational circuits, and both individual and group differences in song are associated with AR abundance. The results reveal how circulating androgens and the auto-regulation of androgen receptors can influence the diverse circuits necessary for elaborate advertisement displays.

Significance statement

Courtship and aggressive displays are among those most elaborate and dramatic of sexually dimorphic behaviors. We show that in Alston’s singing mouse, an androgen-sensitive network defined by retrograde tracing shapes vocal display effort. Our results reveal how the intensity of singing mouse vocalizations is influenced by androgen actions in the vocal motor pathway.
Chronic circadian disruption in adolescent mice impairs hippocampal memory disrupting gene expression oscillations
Authors: Gallego-Landin Ines , Berbegal-Sáez Paula , Valverde Olga
Published: October 2024

Chronodisruption, the misalignment of internal biological systems with external environmental changes, leads to adverse health effects. Particularly, Social Jet Lag (SJL) is defined as the discrepancy between social and biological time and it exemplifies this misalignment, affecting a large part of the young population and impacting cognitive function. Despite its prevalence, our understanding of how developmental chronodisruption ultimately translates into morbidity is limited. To address this, we implemented a chronic chronodisruption protocol in adolescent mice consisting of light/dark cycle manipulation. We employed a comprehensive battery of established behavioral tests alongside an in-depth analysis of the oscillatory expression of the molecular clock and other genes involved in relevant physiological function. Our results show that chronic circadian disruption during adolescence induces impairments in short-term, social, and spatial memory without prompting anxiety-like behavior. Additionally, we report altered gene expression patterns of circadian clock genesper1,per2,cry2andnpas2in the hypothalamus and the hippocampus. Lastly, we observed a disruption of hippocampal gene expression oscillations which may underlie the hippocampal memory impairments. Overall, this work underscores the critical role of adolescent circadian rhythms in maintaining cognitive function, the relevance of circadian control of hippocampal homeostasis, and the importance of further research into the mechanisms of chronodisruption, particularly during adolescence, to better understand its long-term implications for cognitive function and overall health.
Hippocampal place cell sequences are impaired in a rat model of Fragile X Syndrome
Authors: Donahue Margaret M. , Robson Emma , Colgin Laura Lee
Published: October 2024

Fragile X Syndrome (FXS) is a neurodevelopmental disorder that can cause impairments in spatial cognition and memory. The hippocampus is thought to support spatial cognition through the activity of place cells, neurons with spatial receptive fields. Coordinated firing of place cell populations is organized by different oscillatory patterns in the hippocampus during specific behavioral states. Theta rhythms organize place cell populations during awake exploration. Sharp wave-ripples organize place cell population reactivation during waking rest. Here, we examined the coordination of CA1 place cell populations during active behavior and subsequent rest in a rat model of FXS (Fmr1knockout rats). While the organization of individual place cells by the theta rhythm was normal, the coordinated activation of sequences of place cells during individual theta cycles was impaired inFmr1knockout rats. Further, the subsequent replay of place cell sequences was impaired during waking rest following active exploration. Together, these results expand our understanding of how genetic modifications that model those observed in FXS affect hippocampal physiology and suggest a potential mechanism underlying impaired spatial cognition in FXS.

Significance Statement

Fragile X Syndrome (FXS) is a neurodevelopmental disorder that can cause impaired memory and atypical spatial behaviors such as “elopement” (i.e., wandering off and becoming lost). Activity in the CA1 subregion of the hippocampus supports spatial memory and spatial cognition, making it an important candidate to study in the context of FXS; however, how neuronal population activity in CA1 is affected by FXS is poorly understood. In this study, we found that the coordination of populations of CA1 neurons during active behavior and waking rest was impaired in a rat model of FXS. These results reveal hippocampal physiological deficits that may contribute to cognitive impairments in FXS.
Limited Impact of Schistosome Infection onBiomphalaria glabrataSnail Microbiomes
Authors: Nordmeyer Stephanie C. , Anderson Timothy J.C. , Chevalier Frédéric D. , Le Clec’h Winka
Published: October 2024

Background

The microbiome of disease vectors can be a key determinant of their ability to transmit parasites. Conversely, parasite infection may modify vector microbiomes. We are exploring the interactions between theBiomphalaria glabratasnail microbiome and the blood flukeSchistosoma mansoni, responsible for an estimated 200,000 human deaths each year. Snail hosts vary in their susceptibility to schistosome parasites, and the underlying mechanisms driving this variation are not fully understood. We have previously shown that the snail hemolymph (i.e., blood) and organs harbor a diverse microbiome. Here we investigate the impact of schistosome infection on snail microbiomes, hypothesizing that invading schistosomes can alter the snail microbiomes in both composition and abundance over the course of infection, as developing schistosome parasites are in close contact with the host tissues.

Result

We generated cohorts of uninfected andS. mansoniinfected snails. We collected snail hemolymph and hepatopancreas (i.e., liver) at 8 timepoints during the pre-patent and patent periods of schistosome infection. We quantified bacterial density using qPCR and profiled the microbiome composition of all samples by sequencing the V4 region of the 16S rRNA. Schistosome infection had surprisingly no effect on bacterial density and limited effect on the microbiome composition, affecting mainly the hemolymph during the pre-patent period (at day 7 and 21). Organ and hemolymph microbiomes were relatively stable overtime for both infected and uninfected snail cohorts. Thesample type(hemolymph, hepatopancreas) was the major driver of the differences observed in microbiome composition.

Conclusions

The limited impact of schistosome infection on the host snail microbiomes might be explained by the long-term interaction of the two partners and the fact that parasite fitness is closely dependent on host fitness. Further investigations into the interactions between snails, their microbiomes, and schistosome parasites are essential for developing strategies to disrupt the parasite lifecycle and, consequently, schistosomiasis transmission.
Non-lytic spread of poliovirus requires the nonstructural protein 3CD
Authors: Aponte-Diaz David , Harris Jayden M , Kang Tongjia Ella , Korboukh Victoria , Sotoudegan Mohamad S , Gray Jennifer L , Yennawar Neela H , Moustafa Ibrahim M , Macadam Andrew , Cameron Craig E
Published: October 2024

Non-enveloped viruses like poliovirus (PV) have evolved the capacity to spread by non-lytic mechanisms. For PV, this mechanism exploits the host secretory autophagy pathway. Virions are selectively incorporated into autophagosomes, double-membrane vesicles that travel to the plasma membrane, fuse, and release single-membrane vesicles containing virions. Loading of cellular cargo into autophagosomes relies on direct or indirect interactions with microtubule-associated protein 1B-light chain 3 (LC3) that are mediated by motifs referred to as LC3-interaction regions (LIRs). We have identified a PV mutant with a severe defect in non-lytic spread. An F-to-Y substitution in a putative LIR of the nonstructural protein 3CD prevented virion incorporation into LC3-positive autophagosomes and virion trafficking to the plasma membrane for release. Using high-angle annular dark-field scanning transmission electron microscopy to monitor PV-induced autophagosome biogenesis, for the first time, we show that virus-induced autophagic signals yield normal autophagosomes, even in the absence of virions. The F-to-Y derivative of PV 3CD was unable to support normal autophagosome biogenesis. Together, these studies make a compelling case for a direct role of a viral nonstructural protein in the formation and loading of the vesicular carriers used for non-lytic spread that may depend on the proper structure, accessibility, and/or dynamics of its LIR. The studies of PV 3CD protein reported here will hopefully provoke a more deliberate look at the presence and function of LIR motifs in viral proteins of viruses known to use autophagy as the basis for non-lytic spread.
High-resolution mapping of Sigma Factor DNA Binding Sequences using Artificial Promoters, RNA Aptamers and Deep Sequencing
Authors: Khan Essa Ahsan , Rückert-Reed Christian , Dahiya Gurvinder Singh , Tietze Lisa , Fages-Lartaud Maxime , Busche Tobias , Kalinowski Jörn , Shingler Victoria , Lale Rahmi
Published: October 2024

The variable sigma (σ) subunit of the bacterial RNA polymerase holoenzyme determines promoter specificity and facilitate open complex formation during transcription initiation. Understanding σ-factor binding sequences is therefore crucial for deciphering bacterial gene regulation. Here, we present a data-driven high-throughput approach that utilizes an extensive library of 1.54 million DNA templates providing artificial promoters and 5′UTR sequences for σ-factor DNA binding motif discovery. This method combines the generation of extensive DNA libraries,in vitrotranscription, RNA aptamer selection, and deep DNA and RNA sequencing. It allows direct assessment of promoter activity, identification of transcription start sites, and quantification of promoter strength based on mRNA production levels. We applied this approach to map σ54DNA binding sequences inPseudomonas putida. Deep sequencing of the enriched RNA pool revealed 64,966 distinct σ54binding motifs, significantly expanding the known repertoire. This data-driven approach surpasses traditional methods by directly evaluating promoter function and avoiding selection bias based solely on binding affinity. This comprehensive dataset enhances our understanding of σ-factor binding sequences and their regulatory roles, opening avenues for new research in biology and biotechnology.
A PDZ-kinase allosteric relay mediates Par complex regulator exchange
Authors: Vargas Elizabeth , Penkert Rhiannon R. , Prehoda Kenneth E.
Published: October 2024

The Par complex polarizes the plasma membrane of diverse animal cells using the catalytic activity of atypical Protein Kinase C (aPKC) to pattern substrates. Two upstream regulators of the Par complex, Cdc42 and Par-3, bind separately to the complex to influence its activity in different ways. Each regulator binds a distinct member of the complex, Cdc42 to Par-6 and Par-3 to aPKC, making it unclear how they influence one another’s binding. Here we report the discovery that Par-3 binding to aPKC is regulated by aPKC autoinhibition and link this regulation to Cdc42 and Par-3 exchange. The Par-6 PDZ domain activates aPKC binding to Par-3 via a novel interaction with the aPKC kinase domain. Cdc42 and Par-3 have opposite effects on the Par-6 PDZ–aPKC kinase interaction: while the Par-6 kinase domain interaction competes with Cdc42 binding to the complex, Par-3 binding is enhanced by the interaction. The differential effect of Par-3 and Cdc42 on the Par-6 PDZ interaction with the aPKC kinase domain forms an allosteric relay that connects their binding sites and is responsible for the negative cooperativity that underlies Par complex polarization and activity.
Cryo-electron microscopy reveals a single domain antibody with a unique binding epitope on fibroblast activation protein alpha
Authors: Xu Zhen , Sinha Akesh , Pandya Darpan N. , Schnicker Nicholas J. , Wadas Thaddeus J.
Published: October 2024

Fibroblast activation protein alpha (FAP) is a serine protease that is expressed at basal levels in benign tissues but is overexpressed in a variety of pathologies, including cancer. Despite this unique expression profile, designing effective diagnostic and therapeutic agents that effectively target this biomarker remain elusive. Here we report the structural characterization of the interaction between a novel single domain antibody (sdAbs), I3, and FAP using cryo-electron microscopy. The reconstructions were determined to a resolution of 2.7 Å and contained two distinct populations; one I3 bound and two I3 molecules bound to the FAP dimer. In both cases, the sdAbs bound a unique epitope that was distinct from the active site of the enzyme. Furthermore, this report describes the rational mutation of specific residues within the complementarity determining region 3 (CDR3) loop to enhance affinity and selectivity of the I3 molecule for FAP. This report represents the first sdAb-FAP structure to be described in the literature.
Tet Transgene Activation is Disrupted in Lipogenic Triple Negative Breast Cancer Cells
Authors: Townsel Ashley , Wu Yifei , Jaffe Maya , Shields Cara , Haynes Karmella A.
Published: October 2024

An important challenge for mammalian cell engineering is the unexpected response of transgenes to native transcriptional regulation pathways. One transgene can show different levels of expression at different genomic sites, in different cell types, and under different growth conditions. Collisions between transcription and DNA replication, heterochromatin encroachment, and viral defense have been linked to transgene silencing. In this study we identify fatty acid metabolism as another mediator of transgene behavior. Adipocyte secretome-induced lipogenesis in epithelial breast cancer cells was accompanied by the loss of expression from a Tet-TA regulatedpCMV-AmCyan fluorescent protein (CFP) transgene. Transcription profiling verified the activation of lipid droplet biosynthesis genes, and revealed repression of loci at every chromosome, consistent with the idea that lipogenesis affects the availability of substrates and cofactors for global chromatin remodeling. Pre-induction ofpCMVprevented full transgene silencing during lipogenesis. Our results provide new insights into the influence of the lipogenic epigenetic state on transgene behavior.
Isolation and Identification of P(3HB)-Degrading Bacteria from Malaysian Environment
Authors: Zahra Umber , Amirul A.A , Nawaz Ali , Mukhtar Hamid
Published: October 2024

The aim of this study was to identify Poly(3-hydroxybutyrate) [P(3HB)] degrading bacterial strains in Penang Malaysia. Samples were collected from various locations in Penang. Five isolates (SMA-1, SMB-2, SMC-3, SMD-4, and SME-5) with highest P(3HB) degradation indices were isolated through meticulous screening. These gram-negative bacilli were characterized first morphologically and then through scanning electron microscopy. Growth profiles of the isolates revealed that at 24 hrs, SME-5 showed the highest growth rate. Maximum depolymerase enzyme activity for all five isolates was observed after 72 hrs. 16S rDNA sequencing identified all isolates asComamonas testosteroni. This study provides insights into the growth characteristics and extracellular depolymerase activity of P(3HB)-degrading bacteria isolated from the Malaysian environment. It highlights the potential ofComamonas testosteronistrains as P(3HB) bioplastic degraders in diverse habitats.
Drp1-mediated mitochondrial fission protects macrophages from mtDNA/ZBP1-mediated sterile inflammation and inhibits post-infarct cardiac remodeling
Authors: Kondo Yuki , Koga Jun-ichiro , Orkhonselenge Nasanbadrakh , Wang Lixiang , Hasuzawa Nao , Katsuki Shunsuke , Matoba Tetsuya , Nishimura Yosuke , Nomura Masatoshi , Kataoka Masaharu
Published: October 2024

Background

Ischemic heart disease is a leading cause of death worldwide, and heart failure after myocardial infarction (MI) is a growing issue in this aging society. Macrophages play central roles in left ventricular (LV) remodeling after MI. Mitochondria consistently change their morphology, including fission and fusion, but the role of these mitochondrial morphological changes, especially in macrophages, is unknown. This study aims to illuminate the effects and mechanisms of Dynamin-related protein 1 (Drp1), a molecule mediating mitochondrial fission, in macrophages for cardiac remodeling after MI.

Methods

This study utilized genetically altered mice lacking Drp1 in monocytes/macrophages (Drp1-KO) to elucidate the specific role of macrophage Drp1 in post-infarct LV remodeling.

Results

Deletion of Drp1 in macrophages exacerbated LV remodeling, including reduced ejection fraction and increased LV diameters, which resulted in decreased survival after MI. Histological analysis indicated increased fibrosis and sustained macrophage accumulation in Drp1-KO mice. Blockade of Drp1 in macrophages decreased mitochondrial fission and impaired mitophagy, leading to the subsequent release of mitochondrial DNA (mtDNA) to the cytosol and induction of inflammatory cytokines. This induction was abrogated by an autophagy inducer, Tat-beclin1, or siRNA-mediated knockdown of Z-DNA Binding Protein 1 (ZBP1). Deletion of ZBP1 in bone marrow-derived cells abrogated LV remodeling induced by Drp1 inhibitor, Mdivi-1.

Conclusion

Macrophage Drp1 plays a critical role in the pathobiology of LV remodeling after MI, especially mitochondria quality control mechanisms. Macrophage Drp1 could be a novel therapeutic molecule to mitigate the progression of LV remodeling and consequent heart failure after MI.
ASSISTED REPRODUCTIVE TECHNOLOGIES (ART) EQUITY, JUSTICE AND AUTONOMY IN GHANA
Authors: Moses Kodzo Damalie Francis Jojo , Senaya Charles Mawunyo , Damalie Elikplim Adzo , Dankluvi Herbert Ekoe , Osaah Millicent , Yeboah Beatrice , Annan John Jude , Djoleto Ellis Fleischer , Adageba Rudolf Kantum , Odoi Alexander Tawiah
Published: October 2024

Restrictive legislation, which is the main barrier to some assisted reproductive technology (ART) services in many countries, is non-existent in Ghana. However, ART services are concentrated in the capital cities of only four out of the sixteen regions, serving predominantly middle- and upper-class individuals. There is limited evidence about the factors preventing broader access to ART services in Ghana, and this study aims to document these barriers. A cross-sectional survey was conducted in July 2024 across all 22 fertility centers in Ghana, using two structured questionnaires administered via Google App to 61 ART personnel and 104 treatment defaulters. Results showed that mentorship from senior colleagues (65.57%) was the most common way for ART professionals to acquire skills. Almost all (91.80%) professionals offered a full range of ART procedures, but 86.89% advocated for regulated practice. They identified high treatment costs (70.49%) and lack of awareness (16.39%) as the most significant barriers. Among treatment defaulters, 88.47% had sought ART services based on word-of-mouth recommendations, compared to only 4.8% influenced by traditional or social media. More than half (50.96%) of the women were in their thirties, and 48.08% required in vitro fertilization (IVF). While 58.65% sought treatment within five years of infertility, 70.2% discontinued due to high costs, and 35.57% due to partner non-availability. Despite the absence of restrictive policies for ART services in Ghana, Prohibitive costs, partner non-availability, and lack of awareness limit access. However, ART professionals expressed the need for regulated practices.
Strategies to Reduce Hyperglycemia-Related Anxiety in Elite Athletes with Type 1 Diabetes: A Qualitative Analysis
Authors: Katz Alexandra , Shulkin Aidan , Fortier Marc-André , Yardley Jane E. , Kichler Jessica , Housni Asmaa , Talbo Meryem K. , Rabasa-Lhoret Rémi , Brazeau Anne-Sophie
Published: October 2024

Objective

Managing blood glucose levels is challenging for elite athletes with type 1 diabetes (T1D) as competition can cause unpredictable fluctuations. Hyperglycemia-related anxiety (HRA) likely affects performance and diabetes management, but research is limited. This study investigates current strategies employed to mitigate HRA during competition and the development of alternative approaches.

Research Design and Methods

Elite athletes with TID, aged>14 who self-reported HRA during competition were recruited. Elite athletes were defined as individuals exercising >10 hours per week whose athletic performance has achieved the highest competition level. 60 to 90-minute virtual semi-structured interviews were analyzed using an Interpretative Phenomenological Analysis.

Results

Ten elite athletes with T1D (average age 25 ± 3 years; T1D duration 12 ± 8 years; # of competitions per year 27 ± 19; training time per week 12 ± 6 hours) reported the strategies they currently use to mitigate HRA. These strategies include managing insulin and nutrition intake, embracing social support networks, using technology, practicing relaxation techniques, establishing routines, performing pre-competition aerobic exercise, and maintaining adequate sleep hygiene. Several additional approaches that could be implemented were identified including establishing targeted support networks, developing peer-reviewed resources on HRA, ensuring support teams have sufficient tools, and improving existing technology.

Conclusions

Elite athletes with T1D use physiological and psychological strategies to mitigate HRA during competition. This finding highlights the need for increased support and education for these athletes, and advancements in technology. Targeted strategies and personalized approaches are also needed to optimize performance and diabetes management in this population.
Variations in the temperature dependence of photosynthesis among nine common tree species planted in Singapore
Authors: Rachel Teo Li Ming , Yu Liyao , Luo Xiangzhong
Published: October 2024

Tree planting is regarded as one of the most cost-effective ways to mitigate climate change impacts. As a part of the global tree planting movement, the tropical city-state of Singapore initiated a project to plant one million trees in 10 years. However, the environmental impacts (e.g., carbon sequestration, urban cooling) of this reforestation effort are challenging to assess as historically we lack understanding of key plant traits (i.e. photosynthetic capacity, or Vcmax) for species in tropical Asia. Here, we conducted a comprehensive survey of key photosynthetic traits of the nine most popular tree species planted in Singapore and their short-term temperature dependence. We found a three-fold inter-species variation in their photosynthetic capacities (e.g., Vcmaxranges from 20 to 60 μmol m−2s−1) as well as a large discrepancy in their temperature dependence. The photosynthesis of some species (e.g., Tembusu) is more sensitive to rising temperature than others (e.g., Mangroves) while a commonly-used photosynthesis model consistently overestimates photosynthesis but underestimates many species’ temperature sensitivities. The species with smaller temperature sensitivity of photosynthesis is likely related to their stronger ability to adjust leaf temperature via transpiration. Our study provides critical information on the temperature-dependence of photosynthesis of tree species in tropical Asia, which can be used to guide reforestation in Singapore and broadly in Southeast Asia.
Methylthio-alkane reductases use nitrogenase metalloclusters for carbon-sulfur bond cleavage
Authors: Lago-Maciel Ana , Soares Jéssica C. , Zarzycki Jan , Buchanan Charles J. , Reif-Trauttmansdorff Tristan , Schmidt Frederik V. , Lometto Stefano , Paczia Nicole , Schuller Jan M. , Hansen D. Flemming , Heller Gabriella T. , Prinz Simone , Hochberg Georg K. A. , Pierik Antonio J. , Rebelein Johannes G.
Published: October 2024

Methylthio-alkane reductases convert methylated sulfur compounds to methanethiol and small hydrocarbons, a process with important environmental and biotechnological implications. These enzymes are classified as nitrogenase-like enzymes, despite lacking the ability to convert dinitrogen to ammonia, raising fundamental questions about the factors controlling their activity and specificity. Here, we present the first molecular structure of the methylthio-alkane reductase, which reveals large metalloclusters, including the P-cluster and the [Fe8S9C]-cluster, previously only found in nitrogenases. Our findings suggest that distinct metallocluster coordination, surroundings, and substrate channels, determine the activity of these related metalloenzymes. This study provides new insights into nitrogen fixation, sulfur-compound reduction, and hydrocarbon production. We also shed light on the evolutionary history of P-cluster and [Fe8S9C]-cluster-containing reductases emerging prior to nitrogenases.
CRISPR associated enzymes are mislocalized to the cytoplasm in iPSC-derived neurons resulting in KRAB-specific degradation
Authors: Cajka Gregory , Liu Matthew , Shalem Ophir
Published: October 2024

The use of CRISPR-associated enzymes in iPSC-derived neurons for precise gene targeting and high-throughput gene perturbation screens offers great potential but presents unique challenges compared to dividing cell lines. CRISPRi screens in iPSC-derived neurons and glia have already been successful in relating gene function to neurological phenotypes; however, loss of dCas9-KRAB expression after differentiation has been observed by many labs and has been largely ascribed to transgene silencing after differentiation. Here, we investigated the expression levels of different CRISPR enzymes in iPSC and Ngn2-derived neurons using piggybac delivery. We found that the commonly used dCas9-KRAB (using theKOX1domain) displayed dramatic reduction in protein expression levels following neuronal differentiation, yet surprisingly, nCas9 constructs retained comparable protein expression between iPSCs and neurons. We further found that CRISPR constructs, primarily relying on the SV40 Nuclear Localization Signal (NLS), fail to efficiently localize to the nuclei of neurons, despite having robust nuclear levels in iPSCs, leading to KRAB-specific cytoplasmic degradation. By adding a neuronal-specific NLS, we were able to correct neuronal nuclear localization and protein expression, confirming the contribution of mislocalization to the instability of dCas9-KRAB in neurons. As the lack of nuclear localization can have a profound impact on editing and gene perturbation efficiency, we suggest further investigation across both cultured and in-vivo postmitotic cell models.
Impact of methicillin resistance on virulence factor expression inStaphylococcus aureus: Insights from gene expression profiling
Authors: Gharsallah Charfeddine , Ferjani Asma , Ghariani Mouna , Ferjani Sana , Kanzari Lamia , Rehaiem Amel , Fakhfakh Ahmed , Boutiba Ben Boubaker Ilhem
Published: October 2024

Staphylococcus aureusis a major human pathogen causing various clinical infections and a leading cause of morbidity and mortality worldwide. S. aureus infections are problematic due to frequent antibiotic resistance, especially to methicillin. This study investigated 30 unduplicated S. aureus strains from clinical samples to establish a link between methicillin resistance and virulence factors.We detected and determined expression levels of the mecA gene, virulence genes (spdC, spA, atlA), and the RNAIII regulator using qRT-PCR. All virulence genes and the RNAIII regulator were detected in all strains. Phenotypic results showed only three strains (10%) were methicillin-resistant, while 12 (40%) carried the mecA gene. mecA-positive strains exhibited high expression of adhesion factors (spA) and biofilm formation factors (atlA), but low expression of the RNAIII regulator. The regulator’s expression was negatively correlated with mecA gene expression. Using a multilayer association network, we found a correlation between phenotypic methicillin resistance expression and mecA gene transcription inS. aureusmecA+. UnderstandingS. aureusvirulence determinants will help develop anti-virulence strategies, especially given the lack of an anti-S. aureusvaccine and rising antibiotic resistance.

Highlights

Complex interplay between methicillin resistance and virulence:Our study unveils a complex interplay between methicillin resistance and the expression of virulence genes in Staphylococcus aureus clinical isolates.

Phenotypic and molecular correlation:Phenotypic resistance to methicillin was observed in only 10% of the isolates, whereas 40% carried themecAgene. Molecular analysis revealed distinct expression patterns, notably elevatedspAandatlAexpression, inmecA+strains.

Negative correlation withRNAIII:Our findings indicate a negative correlation betweenRNAIIIregulator expression and themecAgene in the same strains, shedding light on their regulatory relationship.

Multilayer association network:Utilizing a multilayer association network, we established a correlation between phenotypic methicillin resistance andmecAgene transcription inS. aureus mecA+strains.
Amino acid competition shapesAcinetobacter baumanniigut carriage
Authors: Ren Xiaomei , Clark R. Mason , Bansah Dziedzom A. , Varner Elizabeth N. , Tiffany Connor R. , Jaswal Kanchan , Geary John H. , Todd Olivia A. , Winkelman Jonathan D. , Friedman Elliot S. , Zemel Babette S. , Wu Gary D. , Zackular Joseph P. , DePas William H. , Behnsen Judith , Palmer Lauren D.
Published: October 2024

Antimicrobial resistance is an urgent threat to human health. Asymptomatic colonization is often critical for persistence of antimicrobial-resistant pathogens. Gut colonization by the antimicrobial-resistant priority pathogenAcinetobacter baumanniiis associated with increased risk of clinical infection. Ecological factors shapingA. baumanniigut colonization remain unclear. Here we show thatA. baumanniiand other pathogenicAcinetobacterevolved to utilize the amino acid ornithine, a non- preferred carbon source.A. baumanniiutilizes ornithine to compete with the resident microbiota and persist in the gut in mice. Supplemental dietary ornithine promotes long-term fecal shedding ofA. baumannii. By contrast, supplementation of a preferred carbon source—monosodium glutamate (MSG)— abolishes the requirement forA. baumanniiornithine catabolism. Additionally, we report evidence for diet promotingA. baumanniigut carriage in humans. Together, these results highlight that evolution of ornithine catabolism allowsA. baumanniito compete with the microbiota in the gut, a reservoir for pathogen spread.
Microglia regulate GABAergic neurogenesis in prenatal human brain through IGF1
Authors: Yu Diankun , Jain Samhita , Wangzhou Andi , De Florencio Stacy , Zhu Beika , Kim Jae Yeon , Choi Jennifer Ja-Yoon , Paredes Mercedes F , Nowakowski Tomasz J , Huang Eric J , Piao Xianhua
Published: October 2024

GABAergic neurons are an essential cellular component of neural circuits. Their abundance and diversity have enlarged significantly in the human brain, contributing to the expanded cognitive capacity of humans. However, the developmental mechanism of the extended production of GABAergic neurons in the human brain remains elusive. Here, we use single-cell transcriptomics, bioinformatics, and histological analyses to uncover microglial regulation of the sustained proliferation of GABAergic progenitors and neuroblasts in the human medial ganglionic eminence (hMGE). We show that insulin-like growth factor 1 (IGF1) and its receptor IGR1R as the top ligand-receptor pair underlying microglia-progenitor communication in the prenatal human brain. Using our newly developed neuroimmune hMGE organoids, which mimics hMGE cytoarchitecture and developmental trajectory, we demonstrate that microglia-derived IGF1 promotes progenitor proliferation and the production of GABAergic neurons. Conversely, IGF1-neutralizing antibodies andIGF1knockout human embryonic stem cells (hESC)-induced microglia (iMG) completely abolished iMG-mediated progenitor proliferation. Together, these findings reveal a previously unappreciated role of microglia-derived IGF1 in promoting proliferation of neural progenitors and the development of GABAergic neurons.
Factors Promoting Lipopolysaccharide Uptake by Synthetic Lipid Droplets
Authors: Arnob Assame , Gairola Anirudh , Clayton Hannah , Jayaraman Arul , Wu Hung-Jen
Published: October 2024

Lipoproteins are essential in removing lipopolysaccharide (LPS) from blood during bacterial inflammation. The physicochemical properties of lipoproteins and environmental factors can impact LPS uptake. In this work, synthetic lipid droplets containing triglycerides, cholesterols, and phospholipids, were prepared to mimic lipoproteins. The physicochemical properties of these lipid droplets, such as charges, sizes, and lipid compositions, were altered to understand the underlying factors affecting LPS uptake. The amphiphilic LPS could spontaneously adsorb on the surface of lipid droplets without lipopolysaccharide binding protein (LBP); however, the presence of LBP can increase LPS uptake. The positively charged lipid droplets also enhance the uptake of negatively charged LPS. Most interestingly, the LPS uptake highly depends on the concentrations of Ca2+near the physiological conditions, but the impact of Mg2+ions was not significant. The increase of Ca2+ions can improve LPS uptake by lipid droplets; this result suggested that Ca2+may play an essential role in LPS clearance. Since septic shock patients typically suffer from hypocalcemia and low levels of lipoproteins, the supplementation of Ca2+ions along with synthetic lipoproteins may be a potential treatment for severe sepsis.
Cultivation conditions of leafy vegetables determine phyllosphere bacterial community structures and ultimately affect growth ofL. monocytogenespost-harvest
Authors: Culliney Paul , Schmalenberger Achim
Published: October 2024

Cultivation conditions including plant species, variety, cultivation method and seasonality are all at least co-factors of epiphytic growth ofL. monocytogenes.Meanwhile, phyllosphere associated bacteria were found to influence colonisation of invading pathogens. Thus, the main objective of this study was to determine whether cultivation conditions are factors in the development of the bacterial phyllosphere community on leafy vegetables which consequently influencesL. monocytogenesgrowth. Indeed, this study revealed that vegetable cultivation condition was a more influential determinant of phyllosphere development than plant species. Of the identified phyllosphere associated bacteria presence ofPseudomonadaceaehad a positive correlation withL. monocytogenespopulations on all tested produce. Yet,Pseudomonadaceaecontent appeared to be more important forL. monocytogenesgrowth on spinach F1 Trumpet. From day 7 to 9 of storage,Pseudomonadaceaeincreases on open field spinach F1 Trumpet were associated withL. monocytogenes’largest increase (0.94 log10cfu g-1), whereasPseudomonadaceaecontent decreased for polytunnel spinach F1 Trumpet and the correspondingL. monocytogenespopulations remained unchanged.Carnobacteriaceaewere present on spinach F1 Trumpet from polytunnel but not on other spinach produce with higher associatedL. monocytogenesgrowth.Pectobacteriaceae(genusDickeya) increased for spinach F1 Trumpet polytunnel but decreased for other spinach produce with lower associatedL. monocytogenesgrowth. Similarly, polytunnel rocket Esmee had an increasing relative abundance ofPectobacteriaceaewhereas it remained constant for polytunnel rocket Buzz. Compared to summer spinach F1 Trumpet produce, winter produce had significantly greaterStreptococcaceaecontent and was correlated with a decrease inL. monocytogenesgrowth. Finally, higher phyllosphere alpha diversity putatively limitedL. monocytogenesgrowth. Ultimately, this study revealed that cultivation conditions determine bacterial phyllosphere community structure which consequently influencesL. monocytogenesgrowth.
Identification and mitigation of blood’s interference with the antimicrobial activity of AgNbO3particles
Authors: Talebpour Cyrus , Fani Fereshteh , Ouellette Marc , Fairfax Marilynn , Alamdari Houshang , Salimnia Hossein
Published: October 2024

The detrimental impact of blood on the antimicrobial activity of AgNbO3particles was identified and investigated. It was observed that the impact is more severe in the case of lysed blood and also operates in the case of commonly used silver salt, AgNO3. The inhibition was shown to be due to hemoglobin, but unrelated to the heme moiety. In an attempt to find additives to mitigate the inhibitory effect of hemoglobin, iron ions and the chelating agent, K2EDTA, were selected as promising candidates. Including iron on the particles was shown to have a marginal effect, but supplying the medium with K2EDTA, an agent preventing clotting of blood samples, fully countered the deleterious impact of hemoglobin on AgNbO3activity. These findings may be relevant for adapting the silver compounds to applications such as wound dressings, where silver’s antimicrobial action would have to take place in a medium containing blood.