Biology subjects

Wilson, C.

Publications and source records attributed to Wilson, C..

At least 55 records · Page 3Linked to original sources

bioRxiv2023

Clinically relevant concurrent BRAF and MEK inhibition alters differentiation states and sensitizes BRAF V600E-mutated high-grade gliomas to immune checkpoint blockade

Resistance to BRAF plus MEK inhibition (BRAFi+MEKi) in BRAFV600E-mutant gliomas drives rebound, progression, and high mortality, yet it remains poorly understood. This study addresses the urgent need to develop treatments for BRAFi+MEKi-resistant glioma in novel mouse models and patient-derived materials. BRAFi+MEKi reveals glioma plasticity by heightening cell state transitions along glial differentiation trajectories, giving rise to astrocyte- and immunomodulatory oligodendrocyte (OL)-like states. PD-L1 upregulation in OL-like cells links cell state transitions to tumor evasion, possibly orchestrated by Galectin-3. BRAFi+MEKi induces interferon response signatures, tumor infiltration, and suppression of T cells. Combining BRAFi+MEKi with immune checkpoint inhibition enhances survival in a T cell-dependent manner, reinvigorates T cells, and outperforms individual or sequential therapies in mice. Elevated PD-L1 expression in BRAF-mutant versus BRAF-wildtype glioblastoma supports the rationale for PD-1 inhibition in patients. These findings underscore the potential of targeting glioma plasticity and highlight combination strategies to overcome therapy resistance in BRAFV600E-mutant HGG. In briefXing et al. show that combined BRAF and MEK inhibitor (BRAFi+MEKi) treatment induces cell state transitions in BRAFV600E-mutant high-grade glioma cells linked with programmed death-ligand (PD-L1) upregulation and T cell suppression, potentially orchestrated through the secretion of galectin-3. These tumor-intrinsic adaptations may be overcome by concurrent immune checkpoint inhibition (ICI), as demonstrated in murine studies, offering novel therapeutic opportunities. HighlightsO_LIBRAFV600E-mutant HGG exhibits cell plasticity induced by BRAFi+MEKi, which links cell state transitions towards glial differentiation with immune evasion C_LIO_LIBRAFi+MEKi enhances anti-tumor immunity and simultaneously suppresses T cells via PD-L1 upregulation C_LIO_LIBRAF-mutant glioblastoma has elevated PD-L1 expression compared to BRAF-wildtype counterparts, providing a criterion for PD-1 inhibition therapy C_LIO_LIConcurrent BRAFi+MEKi and immune checkpoint inhibition enhance T cell-mediated anti-tumor activity and boost survival more effectively than sequential treatment in mice, guiding clinical translation C_LI

cancer biology↗

bioRxiv2022

Co-occurrence and cooperation between comammox and anammox bacteria in a full-scale attached growth municipal wastewater treatment process.

Cooperation between comammox and anammox bacteria for nitrogen removal has been recently reported in laboratory-scale systems including synthetic community construct; however, there are no reports of full-scale municipal wastewater treatment systems with such cooperation. Here, we report intrinsic and extant kinetics as well as genome-resolved community characterization of a full-scale integrated fixed film activated sludge (IFAS) system where comammox and anammox bacteria co-occur and appear to drive nitrogen loss. Intrinsic batch kinetic assays indicated that majority of the aerobic ammonia oxidation was driven by comammox bacteria (1.75 {+/-} 0.08 mg-N/g TS-h) in the attached growth phase with minimal contribution by ammonia oxidizing bacteria. Interestingly, a portion of total inorganic nitrogen ([~]8%) was consistently lost during these aerobic assays. Aerobic nitrite oxidation assays eliminated the possibility of denitrification as a cause of nitrogen loss, while anaerobic ammonia oxidation assays resulted in rates consistent with anammox stoichiometry. Full-scale experiments at different dissolved oxygen (DO = 2-6 mg/L) set points indicated persistent nitrogen loss that was partly sensitive to DO concentrations. Genome-resolved metagenomics confirmed high abundance (relative abundance 6.53 {+/-} 0.34%) of two Brocadia-like anammox populations while comammox bacteria within the Ca. Nitrospira nitrosa cluster were lower in abundance (0.37% {+/-} 0.03%) and Nitrosomonas-like ammonia oxidizers even lower (0.12% {+/-} 0.02%). Collectively, our study reports for the first time the co-occurrence and co-operation of comammox and anammox bacteria in a full-scale municipal wastewater treatment system. SynopsisComammox and anammox cooperation resulted in dissolved oxygen concentration dependent nitrogen loss in municipal wastewater treatment system.

microbiology↗

bioRxiv2022

Low diversity and microdiversity of comammox bacteria in wastewater systems suggests wastewater-specific adaptation within the Ca. Nitrospira nitrosa cluster.

Studies have found Ca. Nitrospira nitrosa-like bacteria to be the principal or sole comammox bacteria in nitrogen removal systems for wastewater treatment. In contrast, multiple populations of strict ammonia and nitrite oxidizers co-exist in similar systems. This apparent lack of diversity is surprising and could impact the feasibility of leveraging comammox bacteria for nitrogen removal. We used full-length 16S rRNA gene sequencing and genome-resolved metagenomics to compare population-level (i.e., species) diversity of comammox bacteria with that of strict nitrifiers in full-scale wastewater treatment systems and assess whether these observations were consistent or diverged at the strain-level. Full-length 16S rRNA gene sequencing indicated that while Nitrosomonas-like bacteria exhibited higher population-level diversity, the effective microdiversity of most Nitrospira-like bacteria were comparatively higher except for one Nitrospira Lineage II population. Comammox bacterial metagenome assembled genomes (MAGs) were associated with Ca. Nitrospira nitrosa. The average amino acid identity between comammox bacterial MAGs (93% {+/-} 3) across systems was significantly higher than that of the Nitrosomonas-like ammonia oxidizers (73%{+/-}8) and the Nitrospira-like nitrite oxidizer MAGs (75%{+/-}13), suggesting that the same comammox population was detected in all systems. Comammox bacteria and some ammonia oxidizers MAGs were significantly less microdiverse than most ammonia and nitrite oxidizers. Interestingly, strain-resolved analysis also indicates that different nitrogen removal systems harbor different comammox bacterial strains within the Ca. Nitrospira nitrosa cluster. These results suggest that comammox bacteria associated with Ca. Nitrospira nitrosa have low species- and strain-level diversity in nitrogen removal systems and may thus harbor specific adaptations to the wastewater ecosystem.

microbiology↗

bioRxiv2022

Delayed processing of blood samples impairs the accuracy of mRNA-based biomarkers

BackgroundThe transcriptome of peripheral white blood cells (PWBCs) contains valuable physiological information, thus making them a prime biological sample for investigating mRNA-based biomarkers. However, prolonged storage of whole blood samples can alter gene transcript abundance in PWBCs, compromising the results of biomarker discovery. Here, we designed an experiment to interrogate the impacts of delayed processing of whole blood samples on gene transcript abundance in PWBCs. We hypothesized that storing blood samples for 24 hours at 4{degrees}C would cause RNA degradation resulting in altered transcriptome profiles. ResultsWe produced RNA-sequencing data for 30 samples collected from five estrus synchronized heifers (Bos taurus). We quantified transcript abundance for 12,414 protein-coding genes in PWBCs. Analysis of parameters of RNA quality revealed no statistically significant differences (P>0.05) between samples collected from the jugular vein and coccygeal vein, as well as among samples processed after one, three, six, or eight hours. However, samples processed after 24 hours of storage had a lower RNA integrity number value (P=0.03) in comparison to those processed after one hour of storage. Next, we analyzed RNA-sequencing data between samples using those processed after one hour of storage as the baseline for comparison. Interestingly, evaluation of 3/5 bias revealed no differences between genes with lower transcript abundance in samples stored for 24 hours relative to one hour. In addition, sequencing coverage of transcripts was similar between samples from the 24-hour and one-hour groups. We identified four and 515 genes with differential transcript abundance in samples processed after storage for eight and 24 hours, respectively, relative to samples processed after one hour. ConclusionsThe PWBCs respond to prolonged cold storage by increasing genes related to active chromatin compaction which in turn reduces gene transcription. This alteration in transcriptome profiles can impair the accuracy of mRNA-based biomarkers. Therefore, blood samples collected for mRNA-based biomarker discovery should be refrigerated immediately and processed within six hours post sampling.

genomics↗

bioRxiv2021

High Expression of Glycolytic Genes in Clinical Glioblastoma Patients Correlates with Lower Survival

Glioblastoma (GBM), the most aggressive brain tumor, is associated with a median survival at diagnosis of 16-20 months and limited treatment options. The key hallmark of GBM is altered tumor metabolism and marked increase in the rate of glycolysis. Aerobic glycolysis along with elevated glucose consumption and lactate production supports rapid cell proliferation and GBM growth. In this study, we examined the gene expression profile of metabolic targets in GBM samples from patients with low grade glioma (LGG) and GBM. We found that gene expression of glycolytic enzymes is up-regulated in GBM samples and significantly associated with an elevated risk for developing GBM. Our findings of clinical outcomes showed that GBM patients with high expression of HK2 and PKM2 in the glycolysis related genes and low expression of genes involved in mitochondrial metabolism-SDHB and COX5A related to tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS), respectively, was associated with poor patient overall survival. Surprisingly, expression levels of genes involved in mitochondrial oxidative metabolism are markedly increased in GBM compared to LGG but was lower compared to normal brain. The fact that in GBM the expression levels of TCA cycle and OXPHOS-related genes are higher than those in LGG patients suggests the metabolic shift in GBM cells when progressing from LGG to GBM. These results are an important step forward in our understanding of the role of metabolic reprogramming in glioma as drivers of the tumor and could be potential prognostic targets in GBM therapies.

cancer biology↗

bioRxiv2021

Compounds enhancing human sperm motility identified using a high-throughput phenotypic screening platform

Study questionCan a high-throughput screening platform facilitate male fertility drug discovery? Summary answerA high-throughput screening platform identified a large number of compounds that enhanced sperm motility. What is known alreadySeveral efforts to find small molecules modulating sperm function have been performed but not using high-throughput technology. Study design, size, durationHealthy donor semen samples were used and samples were pooled (3-5 donors per pool). Primary screening was performed in singlicate; dose-response screening was performed in duplicate (independent donor pools). Participants/materials, setting, methodsSpermatozoa isolated from healthy donors were prepared by density gradient centrifugation and incubated in 384-well plates with compounds (6.25 uM) to identify those compounds with enhancing effects on motility. A total of [~]17,000 compounds from the following libraries: ReFRAME, Prestwick, Tocris, LOPAC, CLOUD and MMV Pathogen Box were screened. Dose response experiments of screening hits were performed to confirm the enhancing effect on sperm motility. Experiments were performed in a University setting. Main results and the role of chanceFrom our primary single concentration screening, 105 compounds elicited an enhancing effect on sperm motility compared to DMSO treated wells. Confirmed enhancing compounds were grouped based on their annotated targets/target classes. A major target class, phosphodiesterase inhibitors, were identified in particular PDE10A inhibitors as well as number of compounds not previously identified/known to enhance human sperm motility such as those related to GABA signaling. Limitations, reasons for cautionCompounds have been tested with prepared donor spermatozoa and only incubated for a short period of time. Therefore, the effect of compounds on whole semen or with longer incubation time may be different. All experiments were performed in vitro. Wider implications of the findingsThis phenotypic screening assay identified a large number of compounds that increased sperm motility. In addition to furthering our understanding of human sperm function, for example identifying new avenues for discovery, we highlight potential inhibitors as promising start-point for a medicinal chemistry programme for potential enhancement of male infertility. Moreover, with disclosure of the results of screening we present a substantial resource to inform further work in the field Study funding/competing interest(s)This study was supported by the Bill and Melinda Gates Foundation and Scottish Funding Council and Scottish Universities Life Science Alliance.

physiology↗

bioRxiv2021

Mitochondrial ATP production is required for endothelial cell control of vascular tone

Arteries and veins are lined by non-proliferating endothelial cells that play a critical role in regulating blood flow. Endothelial cells also regulate tissue perfusion, metabolite exchange, and thrombosis. It is thought that endothelial cells rely on ATP generated via glycolysis to fuel each of these energy-demanding processes. However, endothelial metabolism has mainly been studied in the context of proliferative cells in angiogenesis, and little is known about energy production in endothelial cells within the fully-formed vascular wall. Using intact arteries isolated from rats and mice, we show that inhibiting mitochondrial oxidative phosphorylation disrupts endothelial control of vascular tone. The role for endothelial cell energy production is independent of species, sex, or vascular bed. Basal, mechanically-activated, and agonist-evoked calcium activity in intact artery endothelial cells are each prevented by inhibiting mitochondrial ATP synthesis. This effect is mimicked by blocking the transport of pyruvate, the master fuel for mitochondrial energy production, through the mitochondrial pyruvate carrier. These data show that mitochondrial ATP is necessary for calcium-dependent, nitric oxide mediated endothelial control of vascular tone, and identifies the critical role of endothelial mitochondrial energy production in fueling perfused blood vessel function.

physiology↗

bioRxiv2021

Efficient gradient boosting for prognostic biomarker discovery

MotivationGradient boosting decision tree (GBDT) is a powerful ensemble machine learning method that has the potential to accelerate biomarker discovery from high-dimensional molecular data. Recent algorithmic advances, such as Extreme Gradient Boosting (XGB) and Light Gradient Boosting (LGB), have rendered the GBDT training more efficient, scalable and accurate. These modern techniques, however, have not yet been widely adopted in biomarkers discovery based on patient survival data, which are key clinical outcomes or endpoints in cancer studies. ResultsIn this paper, we present a new R package Xsurv as an integrated solution which applies two modern GBDT training framework namely, XGB and LGB, for the modeling of censored survival outcomes. Based on a comprehensive set of simulations, we benchmark the new approaches against traditional methods including the stepwise Cox regression model and the original gradient boosting function implemented in the package gbm. We also demonstrate the application of Xsurv in analyzing a melanoma methylation dataset. Together, these results suggest that Xsurv is a useful and computationally viable tool for screening a large number of prognostic candidate biomarkers, which may facilitate cancer translational and clinical research. AvailabilityXsurv is freely available as an R package at: https://github.com/topycyao/Xsurv Contactxuefeng.wang@moffitt.org Supplementary informationSupplementary data are available at Bioinformatics online.

bioinformatics↗

bioRxiv2021

Exploring the cytotoxic mechanisms of Pediocin PA-1 towards HeLa and HT29 cells by comparison to known bacteriocins: Microcin E492, Enterocin Heterodimer and Divercin V41.

The purpose of this study was to explore potential mechanisms of cytotoxicity towards HeLa and HT29 cells displayed by Pediocin PA-1. We did this by carrying out sequence alignments and 3D modelling of related bacteriocins which have been studied in greater detail: Microcin E492, Eneterocin AB heterodimer and Divercin V41. Microcin E492 interacts with Toll-Like Receptor 4 in order to activate an apoptosis reaction, sequence alignment showed a high homology between Pediocin PA-1 and Microcin E492 and 3D modelling showed Pediocin PA-1 interacting with TLR-4 in a way reminiscent of Microcin E492. Furthermore, Pediocin PA-1 had the highest homology with the Enterocin heterodimer, particularly chain A; Enterocin has also shown to cause an apoptotic response in cancer cells. Based on this we are led to strongly believe Pediocin PA-1 interacts with TLRs in order to cause cell death. If this is the case it would explain the difference in cytotoxicity towards HeLa over HT29 cells, due to difference in expression of particular TLRs. Overall, we believe Pediocin PA-1 exhibits a dual effect which is dose dependant, like that of Microcin. Unfortunately, the COVID-19 pandemic meant that we were unable to carry out experiments in the lab, and the unavailability of important data meant we were unable to make solid conclusions but rather suggestions. However despite this we have still been able to highlight interesting findings and how these could be translated into future research and therapeutics in order to improve the quality of treatment and life of cancer patients.

cancer biology↗

bioRxiv2021

Rbf/E2F1 control growth and endoreplication via steroid-independent Ecdysone Receptor signalling in Drosophila prostate-like secondary cells

Dysregulation of cell cycle components results in the development and progression of several cancer types. Unusually, loss of the tumour suppressor gene, Retinoblastoma (Rb), and consequent activation of transcription factor E2F1 have been linked to late-stage tumour progression in prostate cancer, rather than early-stage events. This change is associated with an androgen-independent form of cancer, castration-resistant prostate cancer (CRPC), which frequently still requires androgen receptor (AR) signalling. We have previously shown that binucleate secondary cells (SCs) of the Drosophila melanogaster male accessory gland (AG) share several functional and signalling similarities with human prostate epithelial cells. Upon mating, SC growth regulation switches from a steroid-dependent to a steroid-independent form of Ecdysone Receptor (EcR) control that induces genome endoreplication. Here, we demonstrate that the Drosophila Rb homologue, Rbf, and E2F1, as well as cell cycle regulators, Cyclin D (CycD) and Cyclin E (CycE), are key mediators of SC growth and endoreplication both in virgin and mated males. Importantly, we show that the CycD/Rbf/E2F1 axis requires the EcR, but not ecdysone, to trigger CycE-dependent endoreplication and associated growth in SCs after mating, mirroring changes in CRPC. We also demonstrate that excess Rbf activity reversibly suppresses binucleation in adult SCs. Overall, our work reveals mechanistic parallels between the physiological switch to hormone-independent EcR signalling in SCs, and the pathological switch seen in CRPC, and suggests that the latter may represent the dysregulation of a currently unidentified physiological process, which permits AR signalling when androgen levels are low.

cell biology↗

bioRxiv2020

Dissociable Roles of Pallidal Neuron Subtypes in Regulating Motor Patterns

We have previously established that PV+ neurons and Npas1+ neurons are distinct neuron classes in the GPe-- they have different topographical, electrophysiological, circuit, and functional properties. Aside from Foxp2+ neurons, which are a unique subclass within the Npas1+ class, we lack driver lines that effectively capture other GPe neuron subclasses. In this study, we examined the utility of Kcng4-Cre, Npr3-Cre, and Npy2r-Cre mouse lines (both males and females) for the delineation of GPe neuron subtypes. By using these novel driver lines, we have provided the most exhaustive investigation of electrophysiological studies of GPe neuron subtypes to date. Corroborating our prior studies, GPe neurons can be divided into two statistically distinct clusters that map onto PV+ and Npas1+ classes. By combining optogenetics and machine learning-based tracking, we showed that optogenetic perturbation of GPe neuron subtypes generated unique behavioral structures. Our findings further highlighted the dissociable roles of GPe neurons in regulating movement and anxiety-like behavior. We concluded that Npr3+ neurons and Kcng4+ neurons are distinct subclasses of Npas1+ neurons and PV+ neurons, respectively. Finally, by examining local collateral connectivity, we inferred the circuit mechanisms involved in the motor patterns observed with optogenetic perturbations. In summary, by identifying mouse lines that allow for manipulations of GPe neuron subtypes, we created new opportunities for interrogations of cellular and circuit substrates that can be important for motor function and dysfunction. Significance statementWithin the basal ganglia, the external globus pallidus (GPe) has long been recognized for its involvement in motor control. However, we lacked an understanding of precisely how movement is controlled at the GPe level as a result of its cellular complexity. In this study, by using transgenic and cell-specific approaches, we showed that genetically-defined GPe neuron subtypes have distinct roles in regulating motor patterns. In addition, the in vivo contributions of these neuron subtypes are in part shaped by the local, inhibitory connections within the GPe. In sum, we have established the foundation for future investigations of motor function and disease pathophysiology.

neuroscience↗

bioRxiv2020

Bimodal evolution of Src and Abl kinase substrate specificity revealed using mammalian cell extract as substrate pool

The specificity of phosphorylation by protein kinases is essential to the integrity of biological signal transduction. While peptide sequence specificity for individual kinases has been examined previously, here we explore the evolutionary progression that has led to the modern substrate specificity of two non-receptor tyrosine kinases, Abl and Src. To efficiently determine the substrate specificity of modern and reconstructed ancestral kinases, we developed a method using mammalian cell lysate as the substrate pool, thereby representing the naturally occurring substrate proteins. We find that the oldest tyrosine kinase ancestor was a promiscuous enzyme that evolved through a more specific last common ancestor into a specific human Abl. In contrast, the parallel pathway to human Src involved a loss of substrate specificity, leading to general promiscuity. These results add a new facet to our understanding of the evolution of signaling pathways, with both subfunctionalization and neofunctionalization along the evolutionary trajectories.

biochemistry↗

bioRxiv2020

The developmental and genetic architecture of the sexually selected male ornament of swordtails

Sexual selection results in sex-specific characters like the conspicuously pigmented extension of the ventral tip of the caudal fin - the "sword" - in males of several species of Xiphophorus fishes. To uncover the genetic architecture underlying sword formation and to identify genes that are associated with its development, we characterized the sword transcriptional profile and combined it with genetic mapping approaches. Results showed that the male ornament of swordtails develops from a sexually non-dimorphic prepattern of transcription factors in the caudal fin. Among genes that constitute the exclusive sword transcriptome only two are located in the genomic region associated with this trait; the chaperone, fkbp9, and the potassium channel, kcnh8 that in addition to its neural function performs a role known to affect fin growth. This indicates that during evolution of swordtails a brain gene has been recruited for an additional function in establishing a male ornament.

evolutionary biology↗

bioRxiv2020

Accessory ESCRT-III proteins selectively regulate Rab11-exosome biogenesis in Drosophila secondary cells

Exosomes are secreted nanovesicles with potent signalling activity that are initially formed as intraluminal vesicles (ILVs) in multivesicular endosomes, which subsequently fuse with the plasma membrane. These ILVs are made in both late endosomes and recycling endosomes, the latter marked by the small GTPase Rab11 and generating exosomes with different cargos and functions. Core proteins within four Endosomal Sorting Complex Required for Transport (ESCRT) assemblies (0-III) play key sequential roles in late endosomal exosome biogenesis and ILV-mediated destruction of ubiquitinylated cargos through the endolysosomal system. They also control additional cellular processes, such as cytokinesis and other vesicle budding. By contrast, the functions of several accessory ESCRTs are not well defined. Here we assess the ESCRT-dependency of Rab11-exosomes, using RNA knockdown in Drosophila secondary cells (SCs) of the male accessory gland, which have unusually enlarged Rab11-positive compartments. Unexpectedly, not only are core proteins in all four ESCRT complexes required for Rab11-exosome formation, but also accessory ESCRT-III proteins, CHMP1, CHMP5 and IST1. Suppressing expression of these accessory proteins does not affect other aspects of cell morphology, unlike most core ESCRT knockdowns, and does not lead to accumulation of ubiquitinylated cargos. We conclude that accessory ESCRT-III components have a specific and potentially ubiquitin-independent role in Rab11-exosome generation, which might provide a target for blocking the pro-tumorigenic activities of these vesicles in cancer.

cell biology↗

bioRxiv2020

Modeling cell turning by mechanics at the cell rear

In this study, we explore a simulation of a mechanical model of the keratocyte lamellipodium as previously tested and calibrated for straight steady-state motility [1] and for the process of polarization and motility initiation [2]. In brief, this model uses the balance of three essential forces (myosin contraction, adhesive drag and actin network viscosity) to determine the cells mechanical behavior. Cell shape is set by the balance between the actin polymerization-driven protrusion at the cell boundary and myosin-driven retraction of the actin-myosin network. In the model, myosin acts to generate contractile stress applied to a viscous actin network with viscous resistance to actin flow created by adhesion to the substrate. Previous study [3] demonstrated that similar simple model with uniform constant adhesion predicts a rotating behavior of the cell; however, this behavior is idealized, and does not mimic observed features of the keratocytes turning behavior. Our goal is to explore what are the consequences of introducing mechanosensitive adhesions to the model.

biophysics↗

bioRxiv2020

Computer code comprehension shares neural resources with formal logical inference in the fronto-parietal network

Despite the importance of programming to modern society, the cognitive and neural bases of code comprehension are largely unknown. Programming languages might recycle neurocognitive mechanisms originally used for natural languages. Alternatively, comprehension of code could depend on fronto-parietal networks shared with other culturally derived symbol systems, such as formal logic and math. Expert programmers (average 11 years of programming experience) performed code comprehension and memory control tasks while undergoing fMRI. The same participants also performed language, math, formal logic, and executive control localizer tasks. A left-lateralized fronto-parietal network was recruited for code comprehension. Patterns of activity within this network distinguish between "for" loops and "if" conditional code functions. Code comprehension overlapped extensively with neural basis of formal logic and to a lesser degree math. Overlap with simpler executive processes and language was low, but laterality of language and code covaried across individuals. Cultural symbol systems, including code, depend on a distinctive fronto-parietal cortical network.

neuroscience↗

bioRxiv2020

Limited transgenerational effects of environmental temperatures on thermal performance of a cold-adapted salmonid

The capacity of ectotherms to cope with rising temperatures associated with climate change is a significant conservation concern as the rate of warming is likely too fast for adaptation to occur in some populations. Transgenerational plasticity, if present, could potentially buffer some of the negative impacts of warming on future generations. We examined transgenerational plasticity in lake trout to assess their inter-generational potential to cope with anticipated warming. We acclimated adult lake trout to cold or warm temperatures for several months, then bred them to produce offspring from parents of matched and mismatched temperatures. At the fry stage, offspring were also acclimated to cold or warm temperatures and their thermal performance was assessed by measuring their critical thermal maximum and metabolic rate during an acute temperature challenge. Overall, transgenerational plasticity was evident: thermal performance of offspring reflected both maternal and paternal environmental conditions, and offspring performed better when their environment matched that of their parents. There was little variation in offspring critical thermal maximum or peak metabolic rate, although cold-acclimated offspring from warm-acclimated parents exhibited elevated standard metabolic rates, suggesting that transgenerational effects can be detrimental when parent and offspring environments mismatch. These results demonstrate both the occurrence and limitations of transgenerational plasticity in a coldwater salmonid in response to elevated temperature, as well as potential ecological risks associated with transgenerational plasticity when an environmental change experienced by the parents does not persist with the next generation.

physiology↗

bioRxiv2020

Disrupted Endothelial Cell Heterogeneity and Network Organization Impairs Vascular Function in Prediabetic Obesity

RationaleObesity is a major risk factor for diabetes and cardiovascular diseases such as hypertension, heart failure, and stroke. Impaired endothelial function occurs in the earliest stages of obesity and underlies vascular alterations giving rise to cardiovascular disease. However, the mechanisms that link weight gain to endothelial dysfunction are ill-defined. Increasing evidence suggests that, rather than being a population of uniformly responding cells, neighboring endothelial cells are highly heterogeneous and are organized as a communicating multicellular network that controls vascular function. ObjectiveTo investigate the hypothesis that disrupted endothelial heterogeneity and network-level organization contributes to impaired vascular reactivity in obesity. Methods and ResultsTo study obesity-related vascular function without the complications associated with diabetes, we induced a state of prediabetic obesity in rats. Small artery diameter recordings confirmed nitric-oxide mediated vasodilator responses were dependent on increases in endothelial calcium levels and were impaired in obese animals. Single-photon imaging revealed a linear relationship between blood vessel relaxation and network-level calcium responses. Obesity did not alter the slope of this relationship, but impaired network-level endothelial calcium responses. The network itself was comprised of structural and functional components. The structural component, a hexagonal lattice network of endothelial cells, was unchanged in obesity. The functional network contained sub-populations of clustered agonist-sensing cells from which signals were communicate through the network. In obesity there were fewer but larger clusters of agonist-sensing cells and communication path lengths between clusters was increased. Communication between neighboring cells was unaltered in obesity. Altered network organization resulted in impaired, population-level calcium signaling and deficient endothelial control of vascular tone. Specialized subpopulations of endothelial cells had increased agonist sensitivity. These agonist-responsive cells were spatially clustered in a non-random manner and drove network level calcium responses. Communication between adjacent cells was unaltered in obesity, but there was a decrease in the size of the agonist-sensitive cell population and an increase in the clustering of agonist-responsive cells ConclusionsThe distribution of cells in the endothelial network is critical in determining overall vascular function. Altered cell heterogeneity and arrangement in obesity decrease endothelial function and provide a novel framework for understanding compromised endothelial function in cardiovascular disease.

cell biology↗