Biology subjects

Fuller, A.

Publications and source records attributed to Fuller, A..

11 recordsLinked to original sources

bioRxiv2023

Can a flower color ancestral polymorphism transcend speciation?

Polymorphisms are common in nature, but they are rarely shared among closely related species. They could originate through convergence, ancestral polymorphism, or introgression. Although shared neutral genomic variation is commonplace, very few examples of shared functional traits exist. The blue-orange petal color polymorphisms in two closely related species, Lysimachia monelli and L. arvensis were investigated with UV-vis reflectance spectra, flavonoid biochemistry, and transcriptome comparisons followed by climate niche analysis. The similarities in reflectance spectra, biochemistry, and transcriptomes suggest a single shift from blue-to-orange shared by both lineages is possible. Transcriptome comparisons reveal two orange-specific genes are directly involved in both blue-orange color polymorphisms: DFR-2 specificity redirects flux from the malvidin to the pelargonidin while BZ1-2 stabilizes the pelargonidin with glucose, producing the orange pelargonidin 3-glucoside. The climate niches for each color morph are the same between the two species for three temperature characteristics but differ for four precipitation variables. We suggest that this persistent flower color polymorphism may represent an ancestrally polymorphic trait that has transcended speciation with some unique ecological effects.

evolutionary biology↗

bioRxiv2023

A stagewise response to mitochondrial dysfunction in mitochondrial DNA maintenance disorders

Mitochondrial DNA deletions clonally expand in skeletal muscle of patients with mtDNA maintenance disorders, impairing mitochondrial oxidative phosphorylation dysfunction. Previously we have shown that these mtDNA deletions originally arise and accumulate in the perinuclear mitochondria causing localised mitochondrial dysfunction before spreading through the muscle fibre. We believe that mito-nuclear signalling is a key contributor in this process. To further understand the role of mito-nuclear signalling, we use imaging mass cytometry to characterise the levels of mitochondrial respiratory complexes I-IV and ATP synthase alongside a mitochondrial mass marker, in a cohort of patients with mtDNA maintenance dosirders. We then expanded this panel to include protein markers of key signalling pathways to investigate the cellular response in fibres with different combinations of oxidative phosphorylation dysfunction and in ragged red fibres. We find CI and CIV deficiency to be most common, with a smaller proportion of cells that are also CIII and/or CV deficient. Interestingly, we also note that in cells deficient for one or more complexes, any complexes which are not deficient are commonly upregulated beyond the increase of mitochondrial mass typically observed in ragged red fibres. We further find that oxidative phosphorylation deficient fibres exhibit an increase in abundance of proteins involved in the proteostasis e.g. HSP60 and LONP1, and mitochondrial protein synthesis e.g. PHB1. Our analysis suggests that the cellular response to mitochondrial dysfunction changes depending on the combination of deficient oxidative phosphorylation complexes in each cell.

cell biology↗

bioRxiv2023

Estimates of Fall-run Chinook Salmon Escapement in Two San Joaquin River Tributaries from Device-based and Survey-based Methods

Monitoring the escapement (i.e., spawner abundance) of adult salmonids is a fundamental component of fisheries stock assessment and evaluating recovery goals. Whereas multiple methods exist for estimating escapement, they exhibit trade-offs between degree of accuracy and implementation expenses and effort. Various methods are used throughout the Central Valley to estimate escapement of the four runs of Chinook Salmon (Oncorhynchus tshawytscha), but few rivers have more than one escapement monitoring program. Fall-run Chinook Salmon escapement to the Stanislaus and Tuolumne rivers is estimated by two independent monitoring programs on each river. Since 1952, California Department of Fish and Wildlife has performed carcass surveys that provide an index of escapement. Beginning in 2003 (Stanislaus River) and 2009 (Tuolumne River), private contractors have seasonally installed and operated weirs with fish counting devices to enumerate returning adults. We used the overlapping time series to evaluate the relationship between estimates from carcass surveys and the counting weirs. With few exceptions, estimates from counting adult salmon at the weirs as they entered the spawning grounds were greater than estimates from carcass surveys on both rivers. Escapement estimates from the Stanislaus weir were on average 1.7 (SE = 0.07) times greater than estimates from carcass surveys, while estimates at the Tuolumne weir were 2.5 (SE = 0.17) times greater than estimates from carcass surveys. Estimates from both methods were highly correlated, with r2 values > 96% for both rivers. The high degree of covariation between methods indicates escapement estimates are robust and can be used in population models that incorporate additional data sources, such as estimates of juvenile production. Having multiple sources of data on fall-run Chinook Salmon will be increasingly useful for guiding and evaluating management actions in these heavily managed rivers.

zoology↗

bioRxiv2023

Metagenomics uncovers dietary adaptations for chitin digestion in the gut microbiota of convergent myrmecophagous mammals

In mammals, myrmecophagy (ant and termite consumption) represents a striking example of dietary convergence. This trait evolved independently at least five times in placentals with myrmecophagous species comprising aardvarks, anteaters, some armadillos, pangolins, and aardwolves. The gut microbiome plays an important role in dietary adaptation, and previous analyses of 16S rRNA metabarcoding data have revealed convergence in the composition of the gut microbiota among some myrmecophagous species. However, the functions performed by these gut bacterial symbionts and their potential role in the digestion of prey chitinous exoskeletons remain open questions. Using long- and short-read sequencing of fecal samples, we generated 29 gut metagenomes from nine myrmecophagous and closely related insectivorous species sampled in French Guiana, South Africa, and the USA. From these, we reconstructed 314 high-quality bacterial genome bins of which 132 carried chitinase genes, highlighting their potential role in insect prey digestion. These chitinolytic bacteria belonged mainly to the family Lachnospiraceae, and some were likely convergently recruited in the different myrmecophagous species as they were detected in several host orders (i.e., Enterococcus faecalis, Blautia sp), suggesting that they could be directly involved in the adaptation to myrmecophagy. Others were found to be more host-specific, possibly reflecting phylogenetic constraints and environmental influences. Overall, our results highlight the potential role of the gut microbiome in chitin digestion in myrmecophagous mammals and provide the basis for future comparative studies performed at the mammalian scale to further unravel the mechanisms underlying the convergent adaptation to myrmecophagy. ImportanceMyrmecophagous mammals are specialized in the consumption of ants and/or termites. They do not share a direct common ancestor and evolved convergently in five distinct placental orders raising questions about the underlying adaptive mechanisms involved and the relative contribution of natural selection and phylogenetic constraints. Understanding how these species digest their prey can help answer these questions. More specifically, the role of their gut microbial symbionts in the digestion of the insect chitinous exoskeleton has not been investigated in all myrmecophagous orders. We generated 29 new gut metagenomes from nine myrmecophagous species to reconstruct more than 300 bacterial genomes in which we identified chitin-degrading enzymes. Studying the distribution of these chitinolytic bacteria among hosts revealed both shared and specific bacteria between ant-eating species. Overall, our results highlight the potential role of gut symbionts in the convergent dietary adaptation of myrmecophagous mammals and the evolutionary mechanisms shaping their gut microbiota.

evolutionary biology↗

bioRxiv2022

CXCR2 inhibition enables NASH-HCC immunotherapy

ObjectiveHepatocellular carcinoma (HCC) is increasingly associated with non-alcoholic steatohepatitis (NASH). HCC immunotherapy offers great promise; however, recent data suggests NASH-HCC may be less sensitive to conventional immune checkpoint inhibition (ICI). We hypothesised that targeting neutrophils using a CXCR2 small molecule inhibitor may sensitise NASH-HCC to ICI therapy. DesignNeutrophil infiltration was characterised in human HCC and mouse models of HCC. Late-stage intervention with anti-PD1 and/or a CXCR2 inhibitor was performed in murine models of NASH-HCC. The tumour immune microenvironment was characterised by imaging mass cytometry, RNA-seq and flow cytometry. ResultsNeutrophils expressing CXCR2, a receptor crucial to neutrophil recruitment in acute-injury, are highly represented in human NASH-HCC. In models of NASH-HCC lacking response to ICI, the combination of a CXCR2 antagonist with anti-PD1 suppressed tumour burden and extended survival. Combination therapy increased intratumoral XCR1+ dendritic cell activation and CD8+ T cell numbers which are associated with anti-tumoral immunity, this was confirmed by loss of therapeutic effect upon genetic impairment of myeloid cell recruitment, neutralisation of the XCR1-ligand XCL1 or depletion of CD8+ T cells. Therapeutic benefit was accompanied by an unexpected increase in tumour-associated neutrophils (TANs) which switched from a pro-tumor to anti-tumour progenitor-like neutrophil phenotype. Reprogrammed TANs were found in direct contact with CD8+ T cells in clusters that were enriched for the cytotoxic anti-tumoural protease granzyme B. Neutrophil reprogramming was not observed in the circulation indicative of the combination therapy selectively influencing TANs. ConclusionCXCR2-inhibition induces reprogramming of the tumour immune microenvironment that promotes ICI in NASH-HCC. Significance of this studyWhat is already known on this subject? O_LIImmune checkpoint inhibition therapy is emerging as a promising new therapy for the treatment of advanced hepatocellular carcinoma (HCC). C_LIO_LIOnly a minority of HCC patients will respond to immune checkpoint inhibition (ICI) therapy and recent data suggest that HCC on the background of NASH may have reduced sensitivity to this treatment strategy. C_LIO_LINeutrophils are a typical myeloid component of the liver in NASH and are found either within the HCC tumour microenvironment or in a peritumoural location. C_LIO_LINeutrophils have considerable phenotypic plasticity and can exist in both tumour promoting and tumour suppressing states. C_LIO_LINeutrophils may have the ability to influence ICI therapy. C_LI What are the new findings? O_LICXCR2+ neutrophils are found in human NASH and within the tumour of both human and mouse models of NASH-HCC. C_LIO_LIThe resistance of NASH-HCC to anti-PD1 therapy is overcome by co-treatment with a CXCR2 small molecule inhibitor, with evidence of reduced tumour burden and extended survival. C_LIO_LIAnti-PD1 and CXCR2 inhibitor combine to selectively reprogramme tumour-associated neutrophils (TANs) from a pro- to an anti-tumour phenotype. C_LIO_LIReprogrammed TANs proliferate locally within Granzyme B+ immune clusters that contain physically associating CD8+ T cells and antigen presenting cells. C_LIO_LIConventional XCR1+ dendritic cells (cDC1s) are found to be elevated in anti-PD1 and CXCR2 inhibitor treated HCCs and together with CD8+ T cells are required for therapeutic benefit. C_LI How might it impact on clinical practice in the foreseeable future? O_LITANs can be selectively manipulated to adopt an anti-tumour phenotype which unlocks their potential for cancer therapy. The ability of CXCR2 antagonism to combine with ICI therapy to bring about enhanced therapeutic benefit in NASH-HCC (and potentially in HCC of other aetiologies) warrents clinical investigation. C_LI

cancer biology↗

bioRxiv2021

A human iPSC derived bone marrow milieu identifies a novel target against niche-conferred leukaemia proliferation and treatment resistance

Leukaemia cells re-program their microenvironment to provide proliferation support and protection from standard chemotherapy, molecularly targeted therapies, and immunotherapy. Although much is becoming known about molecules that drive niche-dependent treatment resistance; means of targeting these in the clinics has remained a key obstacle. To address this challenge, we have developed human induced pluripotent stem cell engineered niches ex vivo to reveal insights into druggable cancer-niche dependencies. We show that mesenchymal (iMSC) and vascular niche-like (iANG) cells support ex vivo proliferation of patient-derived leukaemia cells, impact dormancy and mediate therapy resistance. iMSC protected both non-cycling and cycling blasts against dexamethasone treatment while iANG protected only dormant blasts. Leukaemia proliferation and protection from dexamethasone induced-apoptosis was dependent on direct cell-cell contact and mediated by CDH2. To explore the therapeutic potential of disrupting this cell-cell interaction, we tested the CDH2 antagonist ADH-1 (previously in phase I / II for solid tumours) in a very aggressive patient-derived xenograft leukaemia mouse model. ADH-1 showed high in vivo efficacy. ADH-1/ dexamethasone combination therapy was superior to dexamethasone alone with no ADH1 conferred additional toxicity. These findings provide a proof-of-concept starting point to develop novel, potentially safer therapeutics that target niche-mediated cancer cell dependencies in haematological malignancies. SummaryCDH2 mediated niche-dependent cancer proliferation and treatment resistance is clinically targetable via ADH-1, a low toxic agent that could be potentially repurposed for future clinical trials in acute leukaemia.

cancer biology↗

bioRxiv2020

Magnitude and kinetics of T cell and antibody responses during H1N1pdm09 infection in outbred and inbred Babraham pigs

We have used the pig, a large natural host animal for influenza with many physiological similarities to humans, to characterize {beta}, {gamma}{delta} T cell and antibody (Ab) immune responses to the 2009 pandemic H1N1 virus infection. We evaluated the kinetic of virus infection and associated response in inbred Babraham pigs with identical MHC (Swine Leucocyte Antigen) and compared them to commercial outbred animals. High level of nasal virus shedding continued up to day 4-5 post infection followed by a steep decline and clearance of virus by day 9. Adaptive T cell and Ab responses were detectable from day 5-6 post infection reaching a peak at 9-14 days. {gamma}{delta} cells produced cytokines ex vivo at day 2 post infection, while virus specific IFN{gamma} producing {gamma}{delta} T cells were detected from day 7 post infection. Analysis of NP tetramer specific and virus specific CD8 and CD4 T cells in blood, lung, lung draining lymph nodes and broncho-alveolar lavage (BAL) showed clear differences in cytokine production between these tissues. BAL contained the most highly activated CD8, CD4 and {gamma}{delta} cells producing large amounts of cytokines, which likely contribute to elimination of virus. The weak response in blood did not reflect the powerful local lung immune responses. The immune response in the Babraham pig following H1N1pdm09 influenza infection was comparable to that of outbred animals. The ability to utilize these two swine models together will provide unparalleled power to analyse immune responses to influenza.

immunology↗

bioRxiv2020

Infrared thermography cannot be used to approximate core body temperature in wild primates

Understanding the physiological processes that underpin primate performance is key if we are to assess how a primate might respond when navigating new and changing environments. Given the connection between an animals ability to thermoregulate and the changing demands of its thermal environment, increasing attention is being devoted to the study of thermoregulatory processes as a means to assess primate performance. Infrared thermography can be used to record the body surface temperatures of free-ranging animals. However, some uncertainty remains as to how these measurements can be used to approximate core body temperature. Here, we use data collected from wild vervet monkeys (Chlorocebus pygerythrus) to examine the relationship between infrared body surface, core body, and local climate, to determine to what extent surface temperatures reflect core body temperature. While we report a positive association between surface and core body temperature - a finding that has previously been used to justify the use of surface temperature measurements as a proxy for core temperature regulation - when we controlled for the effect of the local climate in our analyses, this relationship was no longer observed. That is, body surface temperatures were solely predicted by local climate, and not core body temperatures, suggesting that surface temperatures tell us more about the environment a primate is in, and less about the thermal status of its body core in that environment. Despite the advantages of a non-invasive means to detect and record animal temperatures, infrared thermography alone cannot be used to approximate core body temperature in wild primates.

physiology↗

bioRxiv2020

A cell atlas of human thymic development defines T cell repertoire formation

The thymus provides a nurturing environment for the differentiation and selection of T cells, a process orchestrated by their interaction with multiple thymic cell types. We utilised single-cell RNA-sequencing (scRNA-seq) to create a cell census of the human thymus and to reconstruct T-cell differentiation trajectories and T-cell receptor (TCR) recombination kinetics. Using this approach, we identified and located in situ novel CD8+ T-cell populations, thymic fibroblast subtypes and activated dendritic cell (aDC) states. In addition, we reveal a bias in TCR recombination and selection, which is attributed to genomic position and suggests later commitment of the CD8+ T-cell lineage. Taken together, our data provide a comprehensive atlas of the human thymus across the lifespan with new insights into human T-cell development.

immunology↗

bioRxiv2019

Classification of human white blood cells using machine learning for stain-free imaging flow cytometry

Imaging flow cytometry (IFC) produces up to 12 different information-rich images of single cells at a throughput of 5000 cells per second. Yet often, cell populations are still studied using manual gating, a technique that has several drawbacks. Firstly, it is hard to reproduce. Secondly, it is subjective and biased. And thirdly, it is time-consuming for large experiments. Therefore, it would be advantageous to replace manual gating with an automated process, which could be based on stain-free measurements originating from the brightfield and darkfield image channels. To realise this potential, advanced data analysis methods are required, in particular, machine learning. Previous works have successfully tested this approach on cell cycle phase classification with both a classical machine learning approach based on manually engineered features, and a deep learning approach. In this work, we compare both approaches extensively on the complex problem of white blood cell classification. Four human whole blood samples were assayed on an ImageStream-X MK II imaging flow cytometer. Two samples were stained for the identification of 8 white blood cell types, while two other sample sets were stained for the identification of resting and active eosinophils. For both datasets, four machine learning classifiers were evaluated on stain-free imagery using stratified 5-fold cross-validation. On the white blood cell dataset the best obtained results were 0.776 and 0.697 balanced accuracy for classical machine learning and deep learning, respectively. On the eosinophil dataset this was 0.866 and 0.867 balanced accuracy. From the experiments we conclude that classifying distinct cell types based on only stain-free images is possible with these techniques. However, both approaches did not always succeed in making reliable cell subtype classifications. Also, depending on the cell type, we find that even though the deep learning approach requires less expert input, it performs on par with a classical approach.

bioinformatics↗

bioRxiv2019

Decoding the development of the blood and immune systems during human fetal liver haematopoiesis

Definitive haematopoiesis in the fetal liver supports self-renewal and differentiation of haematopoietic stem cells/multipotent progenitors (HSC/MPPs), yet remains poorly defined in humans. Using single cell transcriptome profiling of ~133,000 fetal liver and ~65,000 fetal skin and kidney cells, we identify the repertoire of blood and immune cells in first and early second trimesters of development. From this data, we infer differentiation trajectories from HSC/MPPs, and evaluate the impact of tissue microenvironment on blood and immune cell development. We predict coupling of mast cell differentiation with erythro-megakaryopoiesis and identify physiological erythropoiesis in fetal skin. We demonstrate a shift in fetal liver haematopoietic composition during gestation away from being erythroid-predominant, accompanied by a parallel change in HSC/MPP differentiation potential, which we functionally validate. Our integrated map of fetal liver haematopoiesis provides a blueprint for the study of paediatric blood and immune disorders, and a valuable reference for understanding and harnessing the therapeutic potential of HSC/MPPs.

developmental biology↗