Biology subjects

Ward, C.

Publications and source records attributed to Ward, C..

At least 19 recordsLinked to original sources

bioRxiv2026

AI-guided analysis of human pancreatic islet sociology reveals distinct cell compositional changes in type 1 diabetes

Human pancreatic islets exhibit greater anatomic and cellular heterogeneity than previously appreciated, raising fundamental questions about how their composition varies with age, sex, region, and islet size and how type 1 diabetes (T1D) alters these relationships. Yet these questions remained largely unresolved due to the bottleneck of manual tissue inspection. Here, we developed an integrated artificial intelligence (AI)-guided imaging, processing, and statistical pipeline enabling unbiased, high-throughput analysis of more than 2 million candidate islets from 106 non-diabetic (ND) and T1D donors. We identified age-, region-, sex-, and islet size-dependent differences in islet distribution and composition between ND and T1D donors. Profound {beta}-cell loss in T1D was accompanied by reciprocal -cell expansion, whereas {delta}-cells and pancreatic polypeptide cells were largely resilient. Cell area and pseudotime analyses uncovered regional and age-dependent trajectories of islet remodeling across T1D progression, along with distinct patterns of cytoarchitectural reorganization of the endocrine pancreas.

pathology↗

bioRxiv2026

Cellector: A tool to detect foreign genotype cells in scRNAseq data with applications in leukemia and microchimerism.

The existence of rare, genetically distinct cells can occur in various samples such as transplant patients, naturally occurring microchimerism between maternal and fetal tissues, and cancer samples with sufficient mutational burden. Computational methods for detecting these foreign cells are vital to studying these biological conditions. An application that is of particular interest is that of leukemia patients post hematopoietic cell transplant (HCT). In many leukemias, a primary therapy is HCT, after which, the primary genotype of the bone marrow and blood cells should be of donor origin. If cells exist that are of the patients genotype and the cell type lineage of the particular leukemia, this is known as measurable residual disease (MRD). If the MRD is high enough, this may represent a relapse of the patients leukemia. Furthermore, accurately estimating the MRD is important for driving clinical decision making for these patients. Here we present Cellector, a computational method for identifying rare foreign genotype cells in single cell RNAseq (scRNAseq) datasets. We show cellector accurately detects microchimeric cells down to an exceedingly low percentage of these cells present (0.05% or lower).

bioinformatics↗

bioRxiv2026

Identification of novel inhibitors of Mycobacterium smegmatis growth through genome-wide overexpression of Cluster P3 mycobacteriophage Xavia genes

We examined whether genes encoded by the mycobacteriophage Xavia disrupt growth of Mycobacterium smegmatis, a widely used mycobacterial model. Seventy-one Xavia genes were individually expressed using an inducible plasmid system and assessed for effects on colony formation. Two genes were lethal even without induction, indicating toxicity under basal expression. Induction of sixteen additional genes reduced bacterial growth, spanning structural proteins, lysogeny regulators, DNA-associated enzymes, a lysis protein, and several genes with no known function. These findings expand functional insights into mycobacteriophage gene repertoires and identify candidates for future mechanistic studies. AbstractBacteriophage genomes encode large numbers of genes with no known function, and many of these genes affect essential host processes when expressed in a heterologous system. For mycobacteriophages, genome-wide overexpression in Mycobacterium smegmatis provides a direct way to identify proteins that impair growth and to determine which mycobacterial pathways are sensitive to phage gene products. To evaluate the cytotoxic potential of the Cluster P3 phage Xavia, a lineage that has not undergone functional screening, we constructed an arrayed pExTra library containing 71 predicted Xavia genes under control of the anhydrotetracycline inducible promoter pTet. All constructs were sequence-verified and transformed into M. smegmatis, and induction allowed measurement of gene-specific effects on growth. Two genes prevented recovery of transformants, suggesting toxicity under basal promoter leakiness. Inducible expression of 16 additional genes impaired growth, and these inhibitory proteins include structural components, regulators of lysogeny, enzymes of DNA metabolism, a lysis factor, and several proteins with no known function. Four of the strongest inhibitors were genes with no known function. These results extend functional screening into the previously untested P3 branch of Actinobacteriophages and identify new proteins that require mechanistic analysis.

microbiology↗

bioRxiv2025

The Synergy between a Silver-Ruthenium Antimicrobial and aminoglycosides is based on severe macromolecular damage

The rise of multidrug-resistant (MDR) bacterial pathogens, including uropathogenic Escherichia coli (UPEC), highlights the urgent need for alternative treatment strategies to restore antibiotic efficacy. The silver-ruthenium antimicrobial AGXX(R) exerts potent bactericidal effects through the production of reactive oxygen species (ROS); however, its potential synergy with antibiotics has not been thoroughly investigated. Here, we show that sublethal concentrations of AGXX(R) strongly enhance aminoglycoside-mediated killing across a diverse panel of Gram-negative and Gram-positive MDR clinical isolates, including highly aminoglycoside-resistant strains. Combinational treatments significantly reduced the effective concentrations of gentamicin, tobramycin, kanamycin, and amikacin required for bacterial killing. Mechanistic analyses revealed that AGXX(R)/aminoglycoside co-treatment induces pronounced intracellular ROS accumulation, resulting in severe proteotoxic stress, extensive protein aggregation, and DNA damage. Scavenging ROS abolished synergistic killing, establishing oxidative imbalance as the primary driver of the synergy between both antimicrobials. We further identify polyphosphate as a key bacterial defense mechanism that mitigates ROS accumulation, proteotoxicity, and genotoxic stress during combinational treatment. Moreover, AGXX(R)-aminoglycoside synergy was preserved in an artificial urine medium and across clinical UPEC isolates, underscoring its relevance to urinary tract infections. Together, these findings position AGXX(R) as a potent aminoglycoside adjuvant that restores antibiotic efficacy through ROS-driven macromolecular damage, supporting its development for combination therapies against MDR bacterial infections.

microbiology↗

bioRxiv2025

Establishing Comprehensive Transthoracic Echocardiography Reference Ranges for Mouse Models: Insights into the Impact of Anesthesia, Sex, and Age

Mouse models play a critical role in cardiology research, offering valuable insights into the molecular mechanisms, genetics, and potential treatments for cardiovascular diseases. However, the ability to transfer findings in mice between studies is limited by the absence of standardized protocols and valid reference values for the assessment of normal cardiac function in mice. This study aims to establish comprehensive transthoracic echocardiography (TTE) reference ranges for mice, particularly focusing on C57BL/6N wildtype controls. The study, which includes data from over 15,000 mice through the International Mouse Phenotyping Consortium (IMPC), highlights how variables such as sex, age, body weight, and anesthesia affect TTE parameters. The findings showed that anesthesia is the primary predictor of variability in cardiac function. Isoflurane and tribromoethanol anesthetized mice presented with modified cardiac function compared to conscious mice. Additionally, we observed minimal sex differences in cardiac morphology and function, except for small variations influenced by anesthesia. The effects of aging on cardiac function were modest, characterized by a decrease in heart rate and subtle changes in ventricular dimensions without evidence of pathological remodeling, likely attributable to disease-free cardiovascular aging. Validation of the reference ranges across multiple mouse strains showed that these values provide a reliable baseline for experiments involving cardiac function in mice. The data underscore the importance of using anesthesia-specific reference values when interpreting TTE results, ensuring robust comparisons in genetic and pharmacological studies. These reference ranges serve as quality assurance tools for future cardiac studies in mice, offering insights into typical TTE parameter values, supporting the detection of experimental perturbations, and contributing to more effective translation of findings from mouse to human.

genetics↗

bioRxiv2025

MYBL2 maintains stemness and promotes theta-mediated end joining in triple negative breast cancer

Triple negative breast cancer (TNBC) has a poor prognosis due to limited treatment options and high metastasis risk. Breast cancer (BC) stem/progenitor cells, also known as tumour initiating cells, are a small, difficult to target population within the tumour responsible for metastasis and therapy resistance. MYBL2 overexpression is commonly linked to poor prognosis and metastasis but its role in BC stem/progenitor cells remains elusive. To determine the role of MYBL2 in BC stem/progenitor cells we generated TNBC cell lines with inducible MYBL2 downregulation. Our findings reveal that elevated MYBL2 is essential for self-renewal, DNA repair, and replication stress response in these cells and lowering MYBL2 impairs stemness and self-renewal both in vitro and in vivo. Accordingly, our functional and mechanistic analyses indicate that high-MYBL2 stem/progenitor cells exhibit increased sensitivity to Pol{theta} inhibitors which is lost upon MYBL2 downregulation due to transcriptional suppression. Combining Pol{theta} inhibitors with ATR inhibitors further enhances this sensitivity, in vitro and ex vivo. This study thus identifies Pol{theta}/ATR inhibition as a synthetic lethality strategy to eradicate BC stem/progenitor cells and underscores MYBL2 expression as a biomarker for patient stratification in this treatment.

cancer biology↗

bioRxiv2024

Cellular behavior analysis from live-cell imaging of TCR T cell-cancer cell interactions

T cell therapies, such as chimeric antigen receptor (CAR) T cells and T cell receptor (TCR) T cells, are a growing class of anti-cancer treatments. However, expansion to novel indications and beyond last-line treatment requires engineering cells dynamic population behaviors. Here we develop the tools for cellular behavior analysis of T cells from live-cell imaging, a common and inexpensive experimental setup used to evaluate engineered T cells. We first develop a state-of-the-art segmentation and tracking pipeline, Caliban, based on human-in-the-loop deep learning. We then build the Occident pipeline to collect a catalog of phenotypes that characterize cell populations, morphology, movement, and interactions in co-cultures of modified T cells and antigen-presenting tumor cells. We use Caliban and Occident to interrogate how interactions between T cells and cancer cells differ when beneficial knock-outs of RASA2 and CUL5 are introduced into TCR T cells. We apply spatiotemporal models to quantify T cell recruitment and proliferation after interactions with cancer cells. We discover that, compared to a safe harbor knockout control, RASA2 knockout T cells have longer interaction times with cancer cells leading to greater T cell activation and killing efficacy, while CUL5 knockout T cells have increased proliferation rates leading to greater numbers of T cells for hunting. Together, segmentation and tracking from Caliban and phenotype quantification from Occident enable cellular behavior analysis to better engineer T cell therapies for improved cancer treatment.

cell biology↗

bioRxiv2024

A secondary β-hydroxybutyrate metabolic pathway linked to energy balance

{beta}-hydroxybutyrate (BHB) is an abundant ketone body. To date, all known pathways of BHB metabolism involve interconversion of BHB and primary energy intermediates. Here we show that CNDP2 controls a previously undescribed secondary BHB metabolic pathway via enzymatic conjugation of BHB and free amino acids. This BHB-ylation reaction produces a family of endogenous ketone metabolites, the BHB-amino acids. Genetic ablation of CNDP2 in mice eliminates tissue amino acid BHB-ylation activity and reduces BHB-amino acid levels. Administration of BHB-Phe, the most abundant BHB-amino acid, to obese mice activates neural populations in the hypothalamus and brainstem and suppresses feeding and body weight. Conversely, CNDP2-KO mice exhibit increased food intake and body weight upon ketosis stimuli. CNDP2-dependent amino acid BHB-ylation and BHB-amino acid metabolites are also conserved in humans. Therefore, the metabolic pathways of BHB extend beyond primary metabolism and include secondary ketone metabolites linked to energy balance.

biochemistry↗

bioRxiv2024

Imaging the interactions of chimeric antigen receptor-expressing T-cells with colorectal cancer cells

Chimeric antigen receptor (CAR) T-cell therapy has shown unprecedented success in haematological cancers but faces challenges in solid tumours. Although carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) is differentially expressed in many solid tumours, anti-CEACAM5 CAR T-cells are ineffective. Here, we have studied the interaction of CEACAM5 targeting primary CAR T-cells with colorectal cancer (CRC) cells using fluorescence microscopy. We found that CRC cells glycocalyx is much deeper than that of the CAR T cell causing delayed activation. Oscillating calcium fluxes, indicative of non-sustained CAR T cell activation and reduced cytotoxicity, were observed when CAR T cells interacted with CRC cells, which increased with increasing cell-seeding time. Imaging revealed that this effect correlated with a progressive loss of accessible CEACAM5 antigen on the CRC cell surface, possibly due to their sequestration in the intercellular junction, rendering CAR T cell engagement less effective. Local proteolytic treatment with trypsin to disrupt the CRC cell monolayer, using a micropipette, increased CEACAM5 availability, decreased glycocalyx thickness, and restored sustained CAR T cell calcium fluxes, increasing the killing of CRC cells. Similar enhanced interaction was observed after treatment of CRC cell monolayer with hyaluronidase, approved for use in humans. We observed limited availability of CEACAM5 on human colorectal cancer tissues, whereas treatment with trypsin or hyaluronidase increased accessibility. Our results reveal why CAR T cells targeting CEACAM5 are ineffective and suggest possible routes to improved therapy for CRC.

immunology↗

bioRxiv2024

Acute microtubule changes linked to DMD pathology are insufficient to impair contractile function or enhance contraction-induced injury in healthy muscle

Duchenne muscular dystrophy (DMD) is marked by the genetic deficiency of the dystrophin protein in striated muscle whose consequence is a cascade of cellular changes that predispose the susceptibility to contraction injury central to DMD pathology. Recent evidence identified the proliferation of microtubules enriched in post-translationally modified tubulin as a consequence of dystrophins absence that increases the passive mechanics of the muscle fiber and the excess mechanotransduction elicited reactive oxygen species and calcium signals that promote contraction injury. Motivated by evidence that acutely normalizing the disease microtubule alterations reduced contraction injury in murine DMD muscle (mdx), here we sought the direct impact of these microtubule alterations independent of dystrophins absence and the multitude of other changes consequent to dystrophic disease. To this end we used acute pharmacologic (epithiolone-D, EpoD; 4 hours) or genetic (vashohibin-2 and small vasohibin binding protein overexpression via AAV9; 2 weeks) strategies to effectively model the proliferation of detyrosination enriched microtubules in the mdx muscle. Quantifying in vivo nerve evoked plantarflexor function we find no alteration in peak torque nor contraction kinetics in WT mice modeling these DMD relevant MT alterations. Quantifying the susceptibility to eccentric contraction injury we show EpoD treatment proffered a small but significant protection from contraction injury while VASH/SVBP had no discernable impact. We conclude that the disease dependent MT alterations act in concert with additional cellular changes to predispose contraction injury in DMD.

physiology↗

bioRxiv2024

Aging disrupts the coordination between mRNA and protein expression in mouse and human midbrain

Age-related dopamine (DA) neuron loss is a primary feature of Parkinsons disease. However, it remains unclear whether similar biological processes occur during healthy aging, albeit to a lesser degree. We therefore determined whether midbrain DA neurons degenerate during aging in mice and humans. In mice, we identified no changes in midbrain neuron numbers throughout aging. Despite this, we found age-related decreases in midbrain mRNA expression of tyrosine hydroxylase (Th), the rate limiting enzyme of DA synthesis. Among midbrain glutamatergic cells, we similarly identified age-related declines in vesicular glutamate transporter 2 (Vglut2) mRNA expression. In co-transmitting Th+/Vglut2+ neurons, Th and Vglut2 transcripts decreased with aging. Importantly, striatal Th and Vglut2 protein expression remained unchanged. In translating our findings to humans, we found no midbrain neurodegeneration during aging and identified age-related decreases in TH and VGLUT2 mRNA expression similar to mouse. Unlike mice, we discovered diminished density of striatal TH+ dopaminergic terminals in aged human subjects. However, TH and VGLUT2 protein expression were unchanged in the remaining striatal boutons. Finally, in contrast to Th and Vglut2 mRNA, expression of most ribosomal genes in Th+ neurons was either maintained or even upregulated during aging. This suggests a homeostatic mechanism where age-related declines in transcriptional efficiency are overcome by ongoing ribosomal translation. Overall, we demonstrate species-conserved transcriptional effects of aging in midbrain dopaminergic and glutamatergic neurons that are not accompanied by marked cell death or lower striatal protein expression. This opens the door to novel therapeutic approaches to maintain neurotransmission and bolster neuronal resilience.

neuroscience↗

bioRxiv2024

Developmental disruption of Mef2c in Medial Ganglionic Eminence-derived cortical inhibitory interneurons impairs cellular and circuit function

MEF2C is strongly linked to various neurodevelopmental disorders (NDDs) including autism, intellectual disability, schizophrenia, and attention-deficit/hyperactivity. Mice constitutively lacking one copy of Mef2c, or selectively lacking both copies of Mef2c in cortical excitatory neurons, display a variety of behavioral phenotypes associated with NDDs. The MEF2C protein is a transcription factor necessary for cellular development and synaptic modulation of excitatory neurons. MEF2C is also expressed in a subset of cortical GABAergic inhibitory neurons, but its function in those cell types remains largely unknown. Using conditional deletions of the Mef2c gene in mice, we investigated the role of MEF2C in Parvalbumin-expressing Interneurons (PV-INs), the largest subpopulation of cortical GABAergic cells, at two developmental timepoints. We performed slice electrophysiology, in vivo recordings, and behavior assays to test how embryonic and late postnatal loss of MEF2C from GABAergic interneurons impacts their survival and maturation, and alters brain function and behavior. We found that loss of MEF2C from PV-INs during embryonic, but not late postnatal, development resulted in reduced PV-IN number and failure of PV-INs to molecularly and synaptically mature. In association with these deficits, early loss of MEF2C in GABAergic interneurons lead to abnormal cortical network activity, hyperactive and stereotypic behavior, and impaired cognitive and social behavior. Our findings indicate that MEF2C expression is critical for the development of cortical GABAergic interneurons, particularly PV-INs. Embryonic loss of function of MEF2C mediates dysfunction of GABAergic interneurons, leading to altered in vivo patterns of cortical activity and behavioral phenotypes associated with neurodevelopmental disorders.

neuroscience↗

bioRxiv2024

Aldehydic load as an objective imaging biomarker of mild traumatic brain injury

Concussion is a mild traumatic brain injury (mTBI) defined as complex neurological impairment induced by biomechanical forces without structural brain damage. There does not yet exist an objective diagnostic tool for concussion. Downstream injury from mTBI stems from oxidative damage leading to the production of neurotoxic aldehydes. A collagen-based 3D corticomimetic scaffold was developed affording an in vitro model of concussion, which confirmed increased aldehyde production in live neurons following impact. To evaluate total aldehyde levels in vivo following mTBI, a novel CEST-MRI contrast agent, ProxyNA3, has been implemented in a new model of closed-head, awake, single-impact concussion developed in aged and young mice with aldehyde dehydrogenase 2 (ALDH2) deficiency. Behavioural tests confirm deficits immediately after injury. ProxyNA3-MRI was performed before impact, and on days two- and seven- post-impact. MRI signal enhancement significantly increased at two days post-injury and decreased to baseline seven days post-injury in all mice. An increase in astrocyte activation at seven days post-injury confirms the onset of a neuroinflammatory response following aldehyde production in the brain. The data suggest that advanced age and ALDH2 deficiency contribute to increased aldehydic load following mTBI. Overall, ProxyNA3 was capable of mapping concussion-associated aldehydes, supporting its application as an objective diagnostic tool for concussion.

biochemistry↗

bioRxiv2024

Airway succinate chemosensing induces CFTR-dependent anion secretion and mucus clearance which is impaired in cystic fibrosis.

The respiratory tract possesses a highly regulated innate defense system which includes efficient cilia-mediated mucus transport or mucociliary clearance (MCC). This essential process relies on appropriate hydration of airway surfaces which is controlled by a blend of transepithelial sodium and liquid absorption via the epithelial sodium channel (ENaC), and anion and liquid secretion, primarily regulated by the cystic fibrosis transmembrane conductance regulator (CFTR) channel. MCC is tightly regulated by second messenger signalling pathways. Succinate is derived from parasites, microorganisms and inflammatory cells, and its concentration increases in the airway surface liquid (ASL) during infections. Increases in ASL succinate activates the G-protein coupled succinate receptor (SUCNR1), which acts as a succinate sensor. Here, we tested the hypothesis that succinate signalling was linked to CFTR activity, ASL hydration and increased MCC. We observed that SUCNR1 activation stimulated anion secretion, increased mucus transport and induced bronchoconstriction in mouse airways. In parallel, stimulation of human bronchial epithelial cells (HBEC) with succinate activated anion secretion and increased ASL height. All functions activated by succinate/SUCNR1 were impeded when working with tissues and cells isolated from animal models or individuals affected cystic fibrosis (CF) or when CFTR was inhibited. Moreover, when HBECs derived from {Delta}F508 individuals were incubated with the triple drug combination of elexacaftor/tezacaftor/ivacaftor (ETI), succinate-induced anion secretion was restored, confirming the tight relationship between SUCNR1 signalling and CFTR function. Our results identify a novel activation pathway for CFTR that participates in the defence response of the airways, which is defective in CF. We propose that succinate acts as a danger molecule that alerts the airways to the presence of pathogens leading to a flushing out of the airways.

physiology↗

bioRxiv2023

Na+/K+ATPase - Cav1.2 nanodomain differentially regulates intracellular and local adrenergic signaling in cardiac myocytes

BackgroundThe intracellular Na+ concentration ([Na+]i) is a crucial but understudied regulator of cardiac myocyte function. The Na+/K+ ATPase (NKA) controls the steady-state [Na+]i and thereby determines the set-point for intracellular Ca2+. Here, we investigate the nanoscopic organization and local adrenergic regulation of the NKA macromolecular complex and how it differentially regulates the intracellular Na+ and Ca2+ homeostases in atrial and ventricular myocytes. MethodsMulticolor STORM super-resolution microscopy, Western Blot analyses, and in vivo examination of adrenergic regulation are employed to examine the organization and function of Na+ nanodomains in cardiac myocytes. Quantitative fluorescence microscopy at high spatiotemporal resolution is used in conjunction with cellular electrophysiology to investigate intracellular Na+ homeostasis in atrial and ventricular myocytes. ResultsThe NKA1 (NKA1) and the L-type Ca2+-channel (Cav1.2) form a nanodomain with a center-to center distance of [~]65 nm in both ventricular and atrial myocytes. NKA1 protein expression levels are [~]3 fold higher in atria compared to ventricle. 100% higher atrial INKA, produced by large NKA "superclusters", underlies the substantially lower Na+concentration in atrial myocytes compared to the benchmark values set in ventricular myocytes. The NKAs regulatory protein phospholemman (PLM) has similar expression levels across atria and ventricle resulting in a much lower PLM/NKA1 ratio for atrial compared to ventricular tissue. In addition, a huge PLM phosphorylation reserve in atrial tissue produces a high {beta}-adrenergic sensitivity of INKA in atrial myocytes. {beta}-adrenergic regulation of INKA is locally mediated in the NKA1-Cav1.2 nanodomain via A-kinase anchoring proteins. ConclusionsNKA1, Cav1.2 and their accessory proteins form a structural and regulatory nanodomain at the cardiac dyad. The tissue-specific composition and local adrenergic regulation of this "signaling cloud" is a main regulator of the distinct global intracellular Na+ and Ca2+ concentrations in atrial and ventricular myocytes.

physiology↗

bioRxiv2023

Surface temperatures are influenced by handling stress independently of glucocorticoid levels in wild king penguins

Assessing the physiological stress responses of wild animals opens a window for understanding how organisms cope with environmental challenges. Since stress response is associated with changes in body temperature, the use of body surface temperature through thermal imaging could help to measure acute and chronic stress responses non-invasively. We used thermal imaging, acute handling-stress protocol and an experimental manipulation of corticosterone (the main glucocorticoid hormone in birds) levels in breeding king penguins (Aptenodytes patagonicus), to assess: 1. the potential contribution of the Hypothalamo-Pituitary-Adrenal (HPA) axis in mediating chronic and acute stress-induced changes in adult surface temperature, 2. the influence of HPA axis manipulation on parental investment through thermal imaging of eggs and brooded chicks, and 3. the impact of parental treatment on offspring thermals response to acute handling. Maximum eye temperature (Teye) increased and minimum beak temperature (Tbeak) decreased in response to handling stress in adults, but neither basal nor stress-induced surface temperatures were significantly affected by corticosterone implant. While egg temperature was not significantly influenced by parental treatment, we found a surprising pattern for chicks: chicks brooded by the (non-implanted) partner of corticosterone-implanted individuals exhibited higher surface temperature (both Teye and Tbeak) than those brooded by glucocorticoid-implanted or control parents. Chicks response to handling in terms of surface temperature was characterized by a drop in both Teye and Tbeak independently of parental treatment. We conclude that the HPA axis seems unlikely to play a major role in determining chronic or acute changes in surface temperature in king penguins. Changes in surface temperature may primarily be mediated by the Sympathetic-Adrenal-Medullary (SAM) axis in response to stressful situations. Our experiment did not reveal a direct impact of parental HPA axis manipulation on parental investment (egg or chick temperature), but a potential influence on the partners brooding behaviour. HighlightsO_LIExperimental increase in corticosterone does not affect king penguins surface temperature C_LIO_LIAcute handling stress increases eye but decreases beak surface temperature in adults C_LIO_LIAcute handling decreases both eye and beak surface temperatures in young chicks C_LIO_LIParental corticosterone treatment does not affect egg surface temperature during incubation C_LIO_LIChicks brooded by non-implanted partners of corticosterone parents are warmer than chicks brooded by others adults. C_LI

zoology↗

bioRxiv2023

Myofibrillar malformations that arise in mdx muscle fibers are driven by detyrosinated microtubules

In Duchenne muscular dystrophy (DMD), alterations in the myofibrillar structure of skeletal muscle fibers that impair contractile function and increase injury susceptibility arise as a consequence of dystrophic pathology. In murine DMD (mdx), myofibrillar alterations are abundant in advanced pathology (>4 months), an age where we formerly established the densification of microtubules (MTs) post-translationally modified by detyrosination (deTyr-MTs) as a negative disease modifier. Given the essential role of MTs in myofibrillar growth, maintenance, and repair, we examined the increased abundance of deTyr-MTs as a potential mechanism for these myofibrillar alterations. Here we find increased levels of deTyr-MTs as an early event in dystrophic pathology (4 weeks) with no evidence of myofibrillar alterations. At 16 weeks, we show the level of deTyr-MTs is significantly increased and co-localized to areas of myofibrillar malformation. Profiling the enzyme complexes responsible for deTyr-tubulin, we identify vasohibin 2 (VASH2) and small vasohibin binding protein (SVBP) significantly elevated in the mdx muscle at 4 wks. We then use the genetic increase in VASH2/SVBP expression in 4 wk wild-type mice and find densified deTyr-MTs that co-segregate with myofibrillar malformations similar to those in the 16 wk mdx. Given that no changes were identified in fibers expressing EGFP as a control, we conclude that disease dependent densification of deTyr-MTs underscores the altered myofibrillar structure in dystrophic skeletal muscle fibers.

pathology↗

bioRxiv2022

An in vivo platform for rebuilding functional neocortical tissue

Recent progress in cortical stem cell transplantation has demonstrated its potential to repair the brain. However, current transplant models have yet to demonstrate that the circuitry of transplant-derived neurons can encode useful function to the host. This is likely due to missing cell types within the grafts, abnormal proportions of cell types, abnormal cytoarchitecture, and inefficient vascularization. Here, we devised a transplant platform for testing neocortical tissue prototypes. Dissociated mouse embryonic telencephalic cells in a liquid scaffold were transplanted into aspiration-lesioned adult mouse cortices. The donor neuronal precursors differentiated into upper and deep layer neurons that exhibited synaptic puncta, projected outside of the graft to appropriate brain areas, became electrophysiologically active within one month post-transplant, and responded to visual stimuli. Interneurons and oligodendrocytes were present at normal densities in grafts. Grafts became fully vascularized by 1-week post-transplant and vessels in grafts were perfused with blood. With this paradigm, we could also organize cells into layers. Overall, we have provided proof of concept for an in vivo platform that can be used for developing and testing neocortical-like tissue prototypes.

neuroscience↗