Biology subjects

George, A. B.

Publications and source records attributed to George, A. B..

11 recordsLinked to original sources

bioRxiv2026

Radiological Patterns in Maxillofacial Ewing Sarcoma: A systematic review with pooled patient-level descriptive analysis

BackgroundEwing sarcoma (ES) is a rare malignant bone tumor with predilection for the mandible and maxilla in the head and neck region. However, existing literature comprises fragmented case reports and small case series that fail to establish consolidated, evidence-based understanding of characteristic radiological patterns in the maxillofacial region, hindering timely diagnosis and potentially leading to misdiagnosis or delayed intervention. MethodologyA systematic review and pooled patient-level descriptive analysis were conducted according to the PRISMA guidelines and pre-registered on PROSPERO. Comprehensive searches of PubMed, OVID, and Cochrane databases (inception to July 2025) identified studies reporting radiological findings of biopsy-confirmed maxillofacial Ewing sarcoma. Quality assessment using Joanna-Briggs Institute criteria ensured inclusion of only high-quality cases (quality score [≥]4/5). Synthesis Without Meta-analysis (SWiM) methodology with pooled prevalence estimation and binomial vote-counting analysis were employed for 68 published cases. ResultsFour radiological features demonstrated consistent predominance across pooled cases: soft tissue mass presence (100%, 95% CI: 94.7-100.0%), enhancing soft tissue (77.6%, 95% CI: 65.8-86.9%), cortical destruction (69.0%, 95% CI: 55.5-80.5%), and notably, absence of periosteal reaction (84.7%, 95% CI: 73.0-92.8%). Location-specific radiological phenotypes were evident: maxillary tumors demonstrated near-universal sinus involvement (100%) with high soft tissue enhancement (92.3%), whereas mandibular tumors showed predominant cortical destruction (80.0%) and teeth involvement (81.2%). ConclusionMRI and CT are essential for characterizing the distinctive radiological profile of maxillofacial Ewing sarcoma, enabling early identification and improving patient outcomes in this rare malignancy. HighlightsO_LIFirst pooled review to summarize imaging features of maxillofacial Ewing sarcoma C_LIO_LIAnalysis of 68 published cases reveals consistent imaging patterns. C_LIO_LIMost tumors show soft tissue mass and bone damage without surface reaction. C_LIO_LIJaw tumors differ from long bone tumors in their imaging appearance. C_LIO_LIUpper and lower jaw tumors show distinct location-specific features. C_LI

cancer biology↗

bioRxiv2025

Phylogenetic relationships and the evolution of fin and body shape in the surgeonfishes

Insights into ecomorphology are enriched when investigating evolutionary correlations between ecologically and functionally important traits. However, tools currently available to model patterns of shape covariation limit researchers to either assume that trait covariances between taxa are independent of, or completely described by, their shared evolutionary history. Using a novel Pagels {lambda} adjustment to incorporate phylogenetic signal in trait covariance analysis, we aim to solve this long-standing problem in phylogenetic comparative methods and investigate ecological associations and evolutionary shape covariation in the ecologically and morphologically diverse case study of surgeonfishes (Acanthuridae). By revising acanthurid phylogenetic relationships and analyzing the geometric morphometrics of their body, head, and fins, we found that head and body shape were significantly associated with dietary ecotype. Surgeonfishes showed a significant negative correlation between caudal fin and pectoral fin shape; high/low aspect ratio (AR) tails are associated with low/high AR pectoral fins, respectively, suggesting locomotor tradeoffs. With our new approach to estimate the influence of phylogeny on trait covariances between taxa, we found the caudal fin covaried with both the body and pectoral fin due to dietary and locomotor demands, respectively and exhibited the highest evolutionary variance along the primary axis of integration in all trait covariance comparisons.

evolutionary biology↗

bioRxiv2024

Higher-Order Interactions in Auxotroph Communities Enhance Their Resilience to Resource Fluctuations

Auxotrophs are prevalent in microbial communities, enhancing their diversity and stability--a counterintuitive effect considering their dependence on essential resources from other species. To address the ecological roles of auxotrophs, our study introduced a novel consumer-resource model that captures the complex higher-order interactions within these communities. We also developed an intuitive graphical and algebraic framework, which assesses the feasibility of auxotroph communities and their stability under resource fluctuations and biological invasions. Validated against experimental data from synthetic E. coli auxotroph communities, the model accurately predicted outcomes of community assembly. Our findings highlight the critical role of higher-order interactions and resource dependencies in maintaining the diversity and stability of microbial ecosystems dominated by auxotrophs.

ecology↗

bioRxiv2023

Sparsity of higher-order interactions enables learning and prediction for microbiomes

Microbiome engineering offers the potential to lever-age microbial communities to improve outcomes in human health, agriculture, and climate. To translate this potential into reality, it is crucial to reliably predict community composition and function. But a brute force approach to cataloguing community function is hindered by the combinatorial explosion in the number of ways we can combine microbial species. An alternative is to parameterize microbial community outcomes using simplified, mechanistic models, and then extrapolate these models beyond where we have sampled. But these approaches remain data-hungry, as well as requiring an a priori specification of what kinds of mechanism are included and which are omitted. Here, we resolve both issues by introducing a new, mechanism-agnostic approach to predicting microbial community compositions and functions using limited data. The critical step is the discovery of a sparse representation of the community landscape. We then leverage this sparsity to predict community compositions and functions, drawing from techniques in compressive sensing. We validate this approach on in silico community data, generated from a theoretical model. By sampling just [~] 1% of all possible communities, we accurately predict community compositions out of sample. We then demonstrate the real-world application of our approach by applying it to four experimental datasets, and showing that we can recover interpretable, accurate predictions on composition and community function from highly limited data.

ecology↗

bioRxiv2022

Universal abundance fluctuations across microbial communities, tropical forests, and urban populations

The growth of complex populations, such as microbial communities, forests, and cities, occurs over vastly different spatial and temporal scales. Although research in different fields has developed detailed, system-specific models to understand each individual system, a unified analysis of different complex populations is lacking; such an analysis could deepen our understanding of each system and facilitate cross-pollination of tools and insights across fields. Here, for the first time we use a shared framework to analyze time-series data of the human gut microbiome, tropical forest, and urban employment. We demonstrate that a single, three-parameter model of stochastic population dynamics can reproduce the empirical distributions of population abundances and fluctuations in all three data sets. The three parameters characterizing a species measure its mean abundance, deterministic stability, and stochasticity. Our analysis reveals that, despite the vast differences in scale, all three systems occupy a similar region of parameter space when time is measured in generations. In other words, although the fluctuations observed in these systems may appear different, this difference is primarily due to the different physical timescales associated with each system. Further, we show that the distribution of temporal abundance fluctuations is described by just two parameters and derive a two-parameter functional form for abundance fluctuations to improve risk estimation and forecasting.

ecology↗

bioRxiv2022

Functional universality in slow-growing microbial communities arises from thermodynamic constraints

The dynamics of microbial communities is complex, determined by competition for metabolic substrates and cross-feeding of byproducts. Species in the community grow by harvesting energy from chemical reactions that transform substrates to products. In many anoxic environments, these reactions are close to thermodynamic equilibrium and growth is slow. To understand the community structure in these energy-limited environments, we developed a microbial community consumer-resource model incorporating energetic and thermodynamic constraints on an intercon-nected metabolic network. The central element of the model is product inhibition, meaning that microbial growth may be limited not only by depletion of metabolic substrates but also by accu-mulation of products. We demonstrate that these additional constraints on microbial growth cause a convergence in the structure and function of the community metabolic network--independent of species composition and biochemical details--providing a possible explanation for convergence of community function despite taxonomic variation observed in many natural and industrial en-vironments. Furthermore, we discovered that the structure of community metabolic network is governed by the thermodynamic principle of maximum free energy dissipation. Our results predict the decrease of functional convergence in faster growing communities, which we validate by ana-lyzing experimental data from anaerobic digesters. Overall, the work demonstrates how universal thermodynamic principles may constrain community metabolism and explain observed functional convergence in microbial communities.

ecology↗

bioRxiv2021

Fin Shape, Asymmetry, and Evolutionary Ecomorphology in Triggerfishes and Filefishes (Superfamily: Balistoidea)

Triggerfishes and filefishes exhibit a wide range of fin and body morphologies, inhabit many marine habitats, and feed on a variety of benthic and pelagic organisms. Particular morphologies are predicted to provide functional advantages for swimming behaviors that facilitate life in diverse habitats and feeding guilds. Ecomorphological relationships can, in turn, inform evolutionary patterns of morphological convergence. We quantified morphological diversity of 80 balistoid species using geometric morphometrics and assigned each species a primary habitat and feeding mode. Results revealed strong evidence for evolutionary integration among body and fin shapes as well as widespread convergence of both high and low aspect ratio (AR) dorsal and anal fins, the fins that power steady locomotion in these fishes. Dorsal and anal fins were determined to be moderately to highly asymmetrical in most species. Families exhibited considerable overlap in fin and body shapes, but triggerfishes generally exhibited higher AR and more asymmetrical fins than filefishes. Fin asymmetry was not strongly associated with ecology. Planktivorous and offshore-pelagic species exhibited high AR dorsal and anal fins suitable for high endurance swimming performance, while benthic grazing and structured reef species exhibited convergence on low AR median fins more suitable for facilitating maneuverability.

evolutionary biology↗

bioRxiv2021

Thermodynamics drives coenzyme redundancy in metabolism

Coenzymes distribute a variety of chemical moieties throughout cellular metabolism, participating in group (e.g., phosphate, acyl) and electron transfer. For a variety of reactions requiring acceptors or donors of specific resources, there often exist degenerate sets of molecules (e.g., NAD(H) and NADP(H)) that carry out similar functions. Although the physiological roles of various coenzyme systems are well established, it is unclear what selective pressures may have driven the emergence of coenzyme redundancy. Here we use genome-wide metabolic modeling approaches to decompose the selective pressures driving enzymatic specificity for either NAD(H) or NADP(H) in the metabolic network of Escherichia coli. We found that few enzymes are thermodynamically constrained to using a single coenzyme, and in principle, a metabolic network relying on only NAD(H) is feasible. However, structural and sequence analyses revealed widespread conservation of residues that retain selectivity for either NAD(H) or NADP(H), suggesting that additional forces may shape specificity. Using a model accounting for the cost of oxidoreductase enzyme expression, we found that coenzyme redundancy universally reduces the minimal amount of protein required to catalyze coenzyme-coupled reactions, inducing individual reactions to strongly prefer one coenzyme over another when reactions are near thermodynamic equilibrium. We propose that protein minimization generically promotes coenzyme redundancy, and that coenzymes typically thought to exist in a single pool (e.g., CoA) may exist in more than one form (e.g., dephospho-CoA). Significance statementMetabolism relies on a small class of molecules (coenzymes) that serve as universal donors and acceptors of key chemical groups and electrons. Although metabolic networks crucially depend on structurally redundant coenzymes (e.g., NAD(H) and NADP(H)) associated with different enzymes, the criteria that led to the emergence of this redundancy remain poorly understood. Our combination of modeling, and structural and sequence analysis indicates that coenzyme redundancy is not essential for metabolism, but rather an evolved strategy promoting efficient usage of enzymes when biochemical reactions are near equilibrium. Our work suggests that early metabolism may have operated with fewer coenzymes, and that adaptation for metabolic efficiency may have driven the rise of coenzyme diversity in living systems.

systems biology↗

bioRxiv2021

Complementary resource preferences spontaneously emerge in diauxic microbial communities

Many microbes grow diauxically, utilizing the available resources one at a time rather than simultaneously. The properties of communities of microbes growing diauxically remain poorly understood, largely due to a lack of theory and models of such communities. Here, we develop and study a minimal model of diauxic microbial communities assembling in a serially diluted culture. We find that unlike co-utilizing communities, diauxic community assembly repeatably and spontaneously leads to communities with complementary resource preferences, i.e., communities where species prefer different resources as their top choice. Simulations and theory explain that the emergence of complementarity is driven by the disproportionate contribution of the top choice resource to the growth of a diauxic species. Additionally, we develop a geometric approach for analyzing serially diluted communities, with or without diauxie, which intuitively explains several additional emergent community properties, such as the apparent lack of species which grow fastest on a resource other than their most preferred resource. Overall, our work provides testable predictions for the assembly of natural as well as synthetic communities of diauxically shifting microbes.

ecology↗

bioRxiv2020

Traveling fronts in self-replicating persistent random walks with multiple internal states

Self-activation coupled to a transport mechanism results in traveling waves that describe polymerization reactions, forest fires, tumor growth, and even the spread of epidemics. Diffusion is a simple and commonly used model of particle transport. Many physical and biological systems are, however, better described by persistent random walks that switch between multiple states of ballistic motion. So far, traveling fronts in persistent random walk models have only been analyzed in special, simplified cases. Here, we formulate the general model of reaction-transport processes in such systems and show how to compute the expansion velocity for arbitrary number of states. For the two-state model, we obtain a closed-form expression for the velocity and report how it is affected by different transport and replication parameters. We also show that nonzero death rates result in a discontinuous transition from quiescence to propagation. We compare our results to a recent observation of a discontinuous onset of propagation in microtubule asters and comment on the universal nature of the underlying mechanism.

biophysics↗

bioRxiv2018

Functional Morphology of Endurance Swimming Performance and Gait Transition Strategies in Balistoid Fishes

Triggerfishes and filefishes (Balistoidea) use balistiform locomotion to power slow steady swimming with their dorsal and anal fins and transition to a gait dominated by body and caudal fin (BCF) kinematics at high speeds. Fin and body shapes are predicted to be strong determinants of swimming performance and the biomechanics of gait transitions. The goal of this study was to combine morphometrics and critical swimming tests to explore relationships between balistoid fin and body shapes and swimming performance in a phylogenetic context in order to understand the evolution and diversification of the balistiform swimming mode. Among the 13 species of balistoid fishes examined, fishes with high aspect ratio fins tended to achieve higher critical swimming speeds than fishes with low aspect ratio fins. Species with long, large median fins and wide caudal peduncles tended to use the balistiform gait alone for a larger percentage of their total critical swimming speed than fishes with short, small median fins and narrow caudal peduncles. Fishes on both ends of the aspect ratio spectrum achieved higher swimming speeds using the balistiform gait alone than fishes with median fins of intermediate aspect ratios. Each species is specialized for taking advantage of one gait, with balistiform specialists possessing long, large median fins capable of the large power requirements of swimming at high speeds using the median fins alone, while BCF specialists possess short, small median fins, ill-suited for powering high-speed balistiform locomotion, but narrow caudal peduncles capable of efficient caudal fin oscillations to power high-speed locomotion.\n\nSummary StatementGeometric morphometrics reveal that fin and body shapes are good predictors of endurance swimming performance and gait transition strategies of triggerfishes and filefishes.

evolutionary biology↗