Biology subjects

King, A.

Publications and source records attributed to King, A..

At least 37 records · Page 2Linked to original sources

bioRxiv2025

A systematic review of climate-change driven range shifts in mosquito vectors

As global temperatures rise, concerns about shifting mosquito ranges--and accompanying changes in the transmission of malaria, dengue, and other diseases--are mounting. However, systematic evidence for climate-driven changes in mosquito ranges remains limited. We conducted a systematic review of studies documenting expansions or contractions in medically important mosquito species. In total, 178 studies on six continents identified range expansions in 118 mosquito species. While over a third of these studies cited warming as a driver, fewer than 10% performed statistical tests of the role of climate. Instead, most expansions were linked to human-aided dispersal (e.g., trade, travel), land-use changes, and urbanization. Although several studies reported poleward or upward expansions consistent with climate warming, none demonstrated warm-edge contractions driven by rising temperatures, which are theoretically predicted in some settings. Rather than expanding into newly suitable areas, many expansions appear to be filling preexisting thermally suitable habitats. Our findings highlight the need for long-term mosquito monitoring, rigorous climate-attribution methods, and better documentation of confounding factors like land-use change and vector control efforts to disentangle climate-driven changes from other anthropogenic factors.

ecology↗

bioRxiv2024

Fig4 confers tolerance to rapamycin in a Ste20-dependent manner independent of the Vac14 scaffold

Summary StatementDisease-related Fig4 mutants displaying impaired association with the Fab1-Vac14-Fig4 complex confer tolerance to rapamycin in Saccharomyces cerevisiae independent of Vac14 in a Ste20-dependent manner. Fig4 can thus modulate homeostasis through association with pathways outside of the Fab1-Vac14-Fig4 complex in yeast. The lipid phosphatase Fig4 modulates the production and turnover of the signaling lipid PI3,5P2 through participation in a complex with its opposing kinase, Fab1, and the scaffold protein Vac14. Fig4 point mutations are associated with neurological diseases for which there are currently no specific therapies. Pathology involving Fig4 is generally attributed to disruption of the Fab1-Vac14-Fig4 complex. Through genetic manipulations in yeast we show that expression of Fig4 disease-related mutants confers tolerance to rapamycin, an inhibitor of the master growth activator TORC1. This phenotype is dominantly conferred at high temperatures by Fig4 mutants that bind poorly to Vac14 or by excess wild-type Fig4. Rapamycin tolerance does not require Fig4 catalytic activity or Vac14, suggesting that Fig4 mediates this altered stress response through context-inappropriate binding interactions with unknown proteins. The p21-activated kinase Ste20 is specifically required for this novel Vac14-independent Fig4 function. Our study shows that Fig4 can modulate homeostasis in Saccharomyces cerevisiae through interactions outside the Fab1-Vac14-Fig4 complex.

cell biology↗

bioRxiv2024

Reversion to sensitivity explains limited transmission of resistance in a hospital pathogen

1Bacterial pathogens that are successful in hospital environments must survive times of intense antibiotic exposure and times of no antibiotic exposure. When these organisms are closely associated with human hosts, they must also transmit from one patient to another for the resistance to spread. The resulting evolutionary dynamics have, in some settings, led to rising levels of resistance in hospitals. Here, we focus on an important but understudied aspect of this dynamic: the loss of resistance when the resistant organisms evolve in environments where the antibiotic pressure is removed. Based on prior data, we hypothesize that resistance arising in the context of strong selection may carry a high cost and revert to sensitivity quickly once the selective pressure is removed. Conversely, resistant isolates that persist through times of no antibiotic pressure should carry a lower cost and revert less quickly. To test this hypothesis, we utilize a genetically diverse set of patient-derived, daptomycin-resistant Enterococcus faecium isolates that include cases of both de novo emergence of resistance within patients and putatively transmitted resistance. Both of these sets of strains have survived periods of antibiotic exposure, but only putatively transmitted resistant strains have survived extended periods without antibiotic exposure. These strains were then allowed to evolve in antibiotic free laboratory conditions. We find that putatively transmitted resistant strains tended to have lower level resistance but that evolution in antibiotic-free conditions resulted in minimal loss of resistance. In contrast, resistance that arose de novo within patients was higher level but exhibited greater declines in resistance in vitro. Sequencing of the experimentally evolved isolates revealed that reversal of high level resistance resulted from evolutionary pathways that were frequently genetically associated with the unique resistance mutations of that strain. Thus, the rapid reversal of high-level resistance was associated with accessible evolutionary pathways where an increase in fitness is associated with decreased resistance. We describe how this rapid loss of resistance may limit the spread of resistance within the hospital and shape the diversity of resistance phenotypes across patients.

microbiology↗

bioRxiv2024

Leveraging the genetic diversity of trout in the rivers of the British Isles and northern France to understand the movements of sea trout (Salmo trutta L.) around the English Channel

Populations of anadromous brown trout, also known as sea trout, have suffered recent marked declines in abundance due to multiple factors, including climate change and human activities. While much is known about their freshwater phase, less is known about the species marine feeding migrations. This situation is hindering the effective management and conservation of anadromous trout in the marine environment. Using a panel of 95 single nucleotide polymorphism markers we developed a genetic baseline, which demonstrated strong regional structuring of genetic diversity in trout populations around the English Channel and adjacent waters. Extensive baseline testing showed this structuring allowed high-confidence assignment of known-origin individuals to region of origin. This study presents new data on the movements of anadromous trout in the English Channel and southern North Sea. Assignment of anadromous trout sampled from 12 marine and estuarine localities highlighted contrasting results for these areas. The majority of these fisheries are composed predominately of stocks local to the sampling location. However, there were multiple cases of long-distance movements of anadromous trout, with several individuals originating from rivers in northeast England being caught in the English Channel and southern North Sea, in some cases more than 1000 km from their natal region. These results have implications for the management of sea trout in inshore waters around the English Channel and southern North Sea.

evolutionary biology↗

bioRxiv2024

GpsB is an accessory Z-ring anchor

Bacterial cytokinesis is a well-coordinated process in which multiple proteins, collectively called the divisome, are recruited to the site of division. A key member of the divisome is FtsZ which forms a ring-like structure (Z-ring) to mark the division site through its association with Z-ring anchors. Synchronized movement of Z-ring filaments and peptidoglycan synthesis along the axis of division help generate a division septum to separate the daughter cells. Thus, FtsZ needs to be linked to the PG synthesis machinery. GpsB is a highly conserved protein among the members of the Firmicutes phylum which has been shown to regulate cell wall synthesis through interaction with penicillin binding proteins. Previously published data from our lab established GpsB as a member of the divisome which directly interacts with FtsZ in Staphylococcus aureus. More specifically, we showed that GpsB binds to FtsZ by recognizing the R-X-X-R sequence in its C- terminal tail (CTT) region. As the GpsB recognition sequence is also present in Bacillus subtilis, we speculated that GpsB-FtsZ interaction might occur in this organism as well. In support of our prediction, previous studies reported that disruption of gpsB and ezrA or gpsB and ftsA is deleterious. Given that both EzrA and FtsA are known Z-ring anchors, we hypothesized that in the absence of other FtsZ anchors, GpsB can fulfill this role in B. subtilis. Our data, taken together, conclusively shows that GpsB is a Z-ring anchor in B. subtilis and this role of GpsB only becomes apparent in the absence of other FtsZ anchoring proteins. Based on the conserved nature of the R-X-X-R sequence in FtsZ- CTT, we also tested GpsB-FtsZ interaction in Enterococcus faecalis and Listeria monocytogenes and show that this recognition motif dependent interaction is present in the former but not the latter. Our results suggest the possibility of C-terminal R-X-X-R independent interaction in L. monocytogenes and Streptococcus pneumoniae. Thus, it appears that GpsB may serve as an accessory Z-ring anchor in multiple organisms. ImportanceCell division is essential for production of offsprings and propagation of life. In bacteria, a key tubulin-like cell division protein FtsZ is brought to the division site by the action of multiple regulators. Arrival of FtsZ and activation of cell wall synthesis are needed to build a division septum to separate the daughter cells. As such, this vital process is controlled by redundant fail-safe mechanisms. For instance, multiple proteins can anchor FtsZ to the membrane at the division site. In this report, we reveal that yet another protein, GpsB, could serve as a back-up FtsZ anchor. GpsB is normally associated with cell wall synthesis in most organisms of the Firmicutes phylum. However, in the absence of other known dedicated FtsZ anchoring factors, GpsB is able to step in to rescue cell division. We provide evidence that this GpsB-FtsZ interaction is present in Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Listeria monocytogenes, and possibly Streptococcus pneumoniae. As the rapid rise in antibiotic resistance is threatening public health globally, knowledge of unique important cell division factors could be harnessed to develop new antibacterial therapeutics.

microbiology↗

bioRxiv2024

Combining Top-Down and Bottom-Up: An Open Microfluidic Microtumor Model for Investigating Tumor Cell-ECM Interaction and Anti-Metastasis

Using a combined top-down (i.e., operator-directed) and bottom-up (i.e., cell-directed) strategy, we present an Under-oil Open Microfluidic System (UOMS)-based microtumor model for investigating tumor cell migration and anti-metastasis drug test. Compared to the mainstream closed microfluidics-based microtumor models, the UOMS microtumor model features: i) micrometer-scale lateral resolution of surface patterning with open microfluidic design for flexible spatiotemporal sample manipulation (i.e., top-down); ii) self-organized extracellular matrix (ECM) structures and tumor cell-ECM spontaneous remodeling (i.e., bottom-up); and iii) free physical access to the samples on a device with minimized system disturbance. The UOMS microtumor model is used to test an anti-metastasis drug (incyclinide, aka CMT-3) with a triple negative breast cancer cell line (MDA-MB-231). The in vitro results show a suppression of tumor cell migration and ECM remodeling echoing with the in vivo mice metastasis results.

bioengineering↗

bioRxiv2024

Motor adaptation to environment changes predicting object behaviour can be flexible and implicit.

The human motor system can adapt to perturbations by updating existing models of motor control or by creating context-specific motor memories or strategies. We investigate if motor adaptation is context-informed when a perturbation is applied to either the throw direction of a ball, or the acceleration of the ball post-release during a virtual throw-to-target task. Using the visual slant of the task surface in an immersive virtual environment, we determine if the tendency for model updating is influenced by informative visual cues that predict perturbations to intended actions. Our findings reveal that perturbations resembling accelerations enabled flexible motor adaptation regardless of the presence of the slant cue. Perturbations in the throw direction conversely led to internal model updating. Additionally, visual slant properties of the task surface elicited implicit, slant-specific changes in performance. Our findings underscore the role of visual properties of both perturbations and environments in flexible motor learning.

neuroscience↗

bioRxiv2023

Shieldin and CST co-orchestrate DNA polymerase-dependent tailed-end joining reactions independently of 53BP1-governed repair pathway choice

53BP1 regulates DNA end-joining in lymphocytes, diversifying immune antigen receptors. This involves nucleosome-bound 53BP1 at DNA double-stranded breaks (DSBs) recruiting RIF1 and shieldin, a poorly understood DNA-binding complex. The 53BP1-RIF1-shieldin axis is pathological in BRCA1-mutated cancers, blocking homologous recombination (HR) and driving illegitimate non-homologous end-joining (NHEJ). However, how this axis regulates DNA end-joining and HR suppression remains unresolved. We investigated shieldin and its interplay with CST, a complex recently implicated in 53BP1-dependent activities. Immunophenotypically, mice lacking shieldin or CST are equivalent, with class-switch recombination co-reliant on both complexes. ATM-dependent DNA damage signalling underpins this cooperation, inducing physical interactions between these complexes that reveal shieldin as a DSB-responsive CST adaptor. Furthermore, DNA polymerase {zeta} functions downstream of shieldin, establishing DNA fill-in synthesis as the physiological function of shieldin-CST. Lastly, 53BP1 suppresses HR and promotes NHEJ in BRCA1-deficient mice and cells independently of shieldin. These findings showcase the resilience of the 53BP1 pathway, achieved through the collaboration of chromatin-bound 53BP1 complexes and DNA end-processing effector proteins.

molecular biology↗

bioRxiv2023

Hypoxia coordinates the spatial landscape of myeloid cells within glioblastoma to affect outcome

Myeloid cells are highly prevalent in glioblastoma (GBM), existing in a spectrum of phenotypic and activation states. We currently have limited knowledge of the tumour microenvironment (TME) determinants that influence the localisation and the functions of the diverse myeloid cell populations in GBM. Here we have utilised orthogonal imaging mass cytometry with single cell and spatial transcriptomics approaches to identify and map the various myeloid populations in the human GBM tumour microenvironment (TME). Our results show that different myeloid populations have distinct and reproducible compartmentalisation patterns in the GBM TME that is driven by tissue hypoxia, regional chemokine signalling, and varied homotypic and heterotypic cellular interactions. We subsequently identified specific tumour sub-regions in GBM, based upon composition of identified myeloid cell populations, that were linked to patient survival. Our results provide new insight into the spatial organisation of myeloid cell sub populations in GBM, and how this is predictive of clinical outcome. TeaserMulti-modal mapping reveals that the spatial organisation of myeloid cells in glioblastoma impacts disease outcome.

cancer biology↗

bioRxiv2023

Assessing Microbial Diversity in Soil Samples Along the Potomac River: Implications for Environmental Health

In this study, we investigated the microbial diversity and community composition of soil samples collected from various sites along the Potomac River within an urbanized region. Our findings revealed the presence of both typical marine soil bacteria and bacterial taxa indicative of urbanization and waste runoff. We observed significant variations in microbial community structure and diversity across different sampling sites, highlighting the influence of environmental factors on microbial abundance and diversity. Through taxon set analysis, we identified shared taxa strongly associated with agricultural pollution, organochlorine pesticide contamination, and bromochloromethane pollution. Additionally, the study revealed potential disparities in human impact, water retention, and tidal/current effects among the soil samples. These insights carry significant implications for understanding the consequences of urbanization on soil microbial communities along the Potomac River and can inform strategies for managing and preserving these ecosystems. Further research is warranted to elucidate the effects of soil health and microbial diversity in this region.

microbiology↗

bioRxiv2023

Cementochronology using synchrotron radiation tomography to determine age at death and developmental rate in the holotype of Homo luzonensis

Homo luzonensis, a fossil hominin from the Philippines, is smaller than modern humans. At present, very little is known about the life history of this species. Cementochronology can answer life history questions, but usually involves destructive sampling. Here, we use synchrotron radiation to count the yearly cement lines of teeth belonging to a single individual. This approach allows us to determine that this individual was likely 31 years old at time of death and apparently had a developmental pattern comparable to chimpanzees. To our knowledge, this is the first time that cementochronology using synchrotron radiation tomography is used for life history and age-at-death estimation.

paleontology↗

bioRxiv2022

Computational Identification of Ligand-Receptor Pairs that Drive Human Astrocyte Development

Extrinsic signaling between diverse cell types is crucial to nervous system development. Ligand binding is a key driver of developmental processes, but it remains a significant challenge to disentangle how collections of these signals act cooperatively to affect changes in recipient cells. In the developing human brain, cortical progenitors transition from neurogenesis to gliogenesis in a stereotyped progression that is influenced by extrinsic ligands. Therefore, we sought to use the wealth of published genomic data in the developing human brain to identify and then test novel ligand combinations that act synergistically to drive gliogenesis. Using computational tools, we identified ligand-receptor pairs that are expressed at appropriate developmental stages, in relevant cell types, and whose activation is predicted to cooperatively stimulate complimentary astrocyte gene signatures. We then tested a group of five neuronally-secreted ligands and validated their synergistic contributions to astrocyte development within both human cortical organoids and primary fetal tissue. We confirm cooperative capabilities of these ligands far greater than their individual capacities and discovered that their combinatorial effects converge on AKT/mTOR signaling to drive transcriptomic and morphological features of astrocyte development. This platform provides a powerful agnostic framework to identify and test how extrinsic signals work in concert to drive developmental processes. HIGHLIGHTSO_LIComputational prediction of active ligand-receptor pairs in the developing brain C_LIO_LISynergistic contributions of predicted ligands drive astrocyte development C_LIO_LILigands induce transcriptomic and morphological features of mature astrocytes C_LIO_LICooperative ligand activity converges on AKT/mTOR signaling C_LI

neuroscience↗

bioRxiv2022

Temporal changes in the microglial proteome of male and female mice after a diffuse brain injury using label-free quantitative proteomics

Traumatic brain injury (TBI) triggers neuroinflammatory cascades mediated by microglia, which promotes tissue repair in the short-term. These cascades may exacerbate TBI-induced tissue damage and symptoms in the months to years post-injury. However, the progression of the microglial function across time post-injury and whether this differs between biological sexes is not well understood. In this study, we examined the microglial proteome in the days (3- and 7-days) to 1 month (28 days) after a midline fluid percussion injury (mFPI) in male and female mice using label-free quantitative proteomics. We identified a reduction in microglial proteins involved with clearance of neuronal debris via phagocytosis at 3- and 7-days post-injury. At 28 days post-injury pro-inflammatory proteins were decreased and anti-inflammatory proteins were increased in microglia. These results indicate a reduction in microglial clearance of neuronal debris in the days post-injury with a shift to anti-inflammatory function by 1 month. The changes in the microglial proteome that occurred across time post-injury did not differ between biological sexes. However, we did identify an increase in microglial proteins related to pro-inflammation as well as insulin and estrogen signalling in males compared with female mice that occurred with or without a brain injury. Although microglial response was similar between males and females up to 1 month following TBI, biological sex differences in the basal microglial proteome has implications for the efficacy of treatment strategies targeting the microglial response post-injury.

neuroscience↗

bioRxiv2022

Defining Predictors of Successful Early Career to Independent Funding Conversion Among Surgeon-Scientists

IntroductionThe National Institutes of Health (NIH) provides research funding to scientists at different stages of their career through a range of grant awards. Early-stage researchers are eligible for mentored Career Development (K) awards, to aid in the transition to independent NIH funding. Factors such as education, subspecialty, and time to funding have been studied as predictors of obtaining independent awards in nonsurgical specialties. However, in surgery, the importance of these factors has yet to be clearly elucidated. We aim to identify predictors of K to independent award conversion among surgeon-scientists to understand how to better support early-stage researchers transitioning to independent careers. Materials and MethodsIn July 2020, the NIH Research Portfolio Online Reporting Tools database was queried for individuals affiliated with surgery departments who received NIH Career Development Awards (between 2000 and 2020). The following factors were analyzed: publications, institution, degrees, year of completion of training, and gender. ResultsBetween 2000 and 2020, 228 surgeons received K Awards, of which 44% transitioned to independent funding. On average, surgeons received a K award 4.0 years after completing fellowship training and an independent award 5.4 years after receiving a K grant. The time to receiving a K award was predictive of successfully achieving independent funding, and those with independent funding had a significantly greater number of publications per year of their K-award. ConclusionSurgeons successful in transitioning to independent NIH awards do so approximately 9 years after finishing fellowship. Publication track record is the main factor associated with successful conversion from a K award. Surgery departments should emphasize manuscript productivity and develop strategies to minimize time to independent funding to help K-awardees begin independent research careers.

scientific communication and education↗

bioRxiv2022

Lung evolution in vertebrates and the water-to-land transition

A crucial evolutionary change in vertebrate history was the Palaeozoic (Devonian ~400 million years ago) water-to-land transition, allowed by key morphological and physiological modifications including the acquisition of lungs. Nonetheless, the origin and early evolution of vertebrate lungs remain highly controversial, particularly whether the ancestral state was paired or unpaired. Due to the rarity of fossil soft tissue preservation, lung evolution can only be traced based on the extant phylogenetic bracket. Here we investigate, for the first time, lung morphology in extensive developmental series of key living lunged osteichthyans using synchrotron X-ray microtomography and histology. Our results shed light on the primitive state of vertebrate lungs as unpaired, evolving to be truly paired in the lineage towards the tetrapods. The water-to-land transition confronted profound physiological challenges and paired lungs were decisive for increasing the surface area and the pulmonary compliance and volume, especially during the air-breathing on land.

evolutionary biology↗

bioRxiv2022

Transient RNA structures cause aberrant influenza virus replication and innate immune activation

During infection, the influenza A virus RNA polymerase produces both full-length and aberrant RNA molecules, such as defective viral genomes (DVG) and mini viral RNAs (mvRNA). Subsequent innate immune activation involves the binding of host pathogen receptor retinoic acid-inducible gene I (RIG-I) to viral RNAs. However, not all influenza A virus RNAs are strong RIG-I agonists. Here we show that potent innate immune activation by mvRNAs is determined by transient RNA structures, called template loops (t-loop) that stall the viral RNA polymerase. The effect of t-loops depends on the formation of an RNA duplex near the template entry and exit channels of the RNA polymerase, and their effect is enhanced by mutation of the template exit path from the RNA polymerase active site. Overall, these findings provide a mechanism that links aberrant viral replication to the activation of the innate immune response.

microbiology↗

bioRxiv2020

Scalable In Vitro Production of Defined Mouse Erythroblasts

Mouse embryonic stem cells (mESCs) can be manipulated in vitro to recapitulate the process of erythropoiesis, during which multipotent cells undergo lineage specification, differentiation and maturation to produce erythroid cells. Although useful for identifying specific progenitors and precursors, this system has not been fully exploited as a source of cells to analyse erythropoiesis. Here, we establish a protocol in which characterised erythroblasts can be isolated in a scalable manner from differentiated embryoid bodies (EBs). Using transcriptional and epigenetic analysis, we demonstrate that this system faithfully recapitulates normal primitive erythropoiesis and fully reproduces the effects of natural and engineered mutations seen in primary cells obtained from mouse models. We anticipate this system to be of great value in reducing the time and costs of generating and maintaining mouse lines in a number of research scenarios. Key PointsO_LIScalable purification of primitive-like erythroid cells from in vitro differentiated mESCs offers tractable tools for genetic studies C_LIO_LIIn vitro derived erythroid cells recapitulate wild type and engineered mutation phenotypes observed in primary cells obtained from mouse models C_LI

molecular biology↗

bioRxiv2020

Seasonal and long-term consequences of esca on grapevine stem xylem integrity

Hydraulic failure has been extensively studied during drought-induced plant dieback, but its role in plant-pathogen interactions is under debate. During esca, a grapevine (Vitis vinifera) disease, symptomatic leaves are prone to irreversible hydraulic dysfunctions but little is known about the hydraulic integrity of perennial organs over the short- and long-term. We investigated the effects of esca on stem hydraulic integrity in naturally infected plants within a single season and across season(s). We coupled direct (ks) and indirect (kth) hydraulic conductivity measurements, and tylose and vascular pathogen detection with in vivo X-ray microtomography visualizations. We found xylem occlusions (tyloses), and subsequent loss of stem ks, in all of the shoots with severe symptoms (apoplexy) and in more than 60% of the shoots with moderate symptoms (tiger-stripe), and no tyloses in shoots that were currently asymptomatic. In vivo stem observations demonstrated that tyloses were observed only when leaf symptoms appeared, and resulted in more than 50% PLC in 40% of symptomatic stems, unrelated to symptom age. The impact of esca on xylem integrity was only seasonal and no long-term impact of disease history was recorded. Our study demonstrated how and to what extent a vascular disease such as esca, affecting xylem integrity, could amplify plant mortality by hydraulic failure. HighlightOur study reveals that esca can critically affect xylem water movement in grapevine perennial organs, by the presence of plant-derived tyloses.

plant biology↗