Biology subjects

Morrissey, J.

Publications and source records attributed to Morrissey, J..

9 recordsLinked to original sources

bioRxiv2026

Multi-Objective Bayesian Optimization for Data-Efficient Bioprocess Development

Process optimization for Chinese hamster ovary (CHO) cell culture remains a challenge in biopharmaceutical development because multiple interacting parameters jointly influence productivity and product quality attributes. Traditional design-of-experiments (DoE) methods, while systematic, become impractically expensive when extended across multiple parameters and clones. To address this challenge, we developed a multi-objective Bayesian Optimization (BO) framework that identifies optimal process conditions efficiently in grouped recommendations, which is well suited for experimental workflows in bioprocess development. The model integrates continuous variables such as pH, DO, temperature, and feed rate with categorical identifiers to enable knowledge transfer across clones and scales, optimizing titer, glycan profile, and charge variants. We validated the framework through in-silico benchmarks on analytic functions, retrospective cross-validation on historical CHO datasets, and forward experimental validation in small-scale bioreactors. Across these tests, our algorithm consistently outperformed Latin Hypercube Sampling (LHS) and Random Search baselines, achieving superior performance under a limited experimental budget. The framework improved titer by up to 37% under single-objective optimization. In the multi-objective setting, it increased titer by 25% while simultaneously reducing overall glycan-profile error by a factor of seven, demonstrating the ability to optimize multiple biologically coupled objectives simultaneously. Through comprehensive in-silico and experimental validation, this study establishes a framework that enables adaptive, AI-guided process development and improves decision-making across multiple objectives, clones, and scales while minimizing experimental runs in process development and optimization workflows.

bioengineering↗

bioRxiv2026

MCBO: Mammalian Cell Bioprocessing Ontology, A Hub-and-Spoke, IOF-Anchored Application Ontology

Mammalian cell-based biopharmaceutical manufacturing generates vast, heterogeneous datasets that remain fragmented due to the lack of a standardized metadata framework. A key challenge in biologics manufacturing is linking bioreactor conditions, cell line characteristics and recombinant product production. A datahub for mammalian cell bioprocessing, integrated by semantic technologies, will serve as a tool to understand and query the connections between these complex datasets. While existing ontologies cover general biological and experimental concepts, they often lack the operational specificity required to harmonize bioreactor conditions, cell line engineering, and product quality metrics. To address this specific gap, we present the Mammalian Cell Bioprocessing Ontology (MCBO), a hub-and-spoke application ontology built on Basic Formal Ontology (BFO) foundations and anchored to the Industrial Ontology Foundry (IOF) Core. MCBO formalizes the process-participant-quality modeling pattern, enabling precise tracking of culture environmental conditions as qualities of the physical culture system. We demonstrate the utility of MCBO through a central datahub populated with 723 curated cell culture process instances and 325 unique bioprocess samples from published studies. The framework is validated against eight competency questions implemented via SPARQL, demonstrating efficient cross-study querying of culture optimization, cell line engineering, and multi-omics integration. By providing a stable, schema-independent substrate for data harmonization, MCBO enables AI agent-powered, human-in-the-loop workflows and facilitates LLM-assisted extraction of structured metadata from legacy records. MCBO is open-source and designed for deployment behind institutional firewalls to support interoperable biomanufacturing intelligence while maintaining intellectual property sensitivity. MCBO is supported by the International Biomanufacturing Network (IBioNe), which aims to accelerate discoveries and developments by providing a network of biomanufacturing training and workforce development to educate the next generation of biomanufacturing experts. MCBO is evaluated using over 700 curated cell culture processes, validated against eight competency questions, and quality-controlled using automated ontology checks. Evaluation results and formal reasoning validation are provided in the Supplementary Materials. Availability: https://github.com/lewiscelllabs/mcbo

bioinformatics↗

bioRxiv2025

Inferring the Metabolic Objectives of Mammalian Cells via Inverse Modeling of Fluxomics and Metabolomics

Metabolism reflects evolutionary priorities that govern how cells allocate resources. In mammalian cells, metabolic objectives are layered and context-dependent, making it difficult to pinpoint the priorities that underlie observed phenotypes. Here, we introduce ObjFind-M, an inverse optimization framework that infers reaction-level metabolic objectives in mammalian cells directly from fluxomic and metabolomic data. Using Chinese hamster ovary (CHO) cells as a data-rich mammalian cell system, ObjFind-M consistently identifies mitochondrial ATP synthase as the central metabolic driver, supported by key TCA cycle and electron transport chain nodes. Priorities adjust with cellular state, favoring glycolysis-TCA coupling in the growth phase and shifting toward oxidative phosphorylation and redox balance when proliferative activity slows. High recombinant protein producing CHO cells emphasize citrate shuttling and beta-oxidation, linking energy supply with biosynthetic capacity for protein secretion. Benchmarking against conventional objectives demonstrates that maximizing ATP production most accurately reproduces experimental fluxes. By quantifying metabolic objectives directly from data rather than assuming them a priori, ObjFind-M provides a framework for identifying reaction-level strategies that shape cellular decision making. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=76 SRC="FIGDIR/small/677837v1_ufig1.gif" ALT="Figure 1"> View larger version (18K): org.highwire.dtl.DTLVardef@5c507aorg.highwire.dtl.DTLVardef@a7b544org.highwire.dtl.DTLVardef@6db0d4org.highwire.dtl.DTLVardef@17464e2_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIObjFind-M, an inverse FBA framework, infers reaction-level metabolic objectives from fluxomic and metabolomic data. C_LIO_LIATP synthase (Complex V) emerges as the top reaction, supported by NADH-generating TCA reactions such as the -ketoglutarate dehydrogenase complex. C_LIO_LICHO cells suppress formation of toxic or wasteful byproducts while emphasizing energy-efficient flux routing. C_LIO_LIGrowth vs. non-growth phases reveal shifts between biosynthesis and oxidative phosphorylation. C_LIO_LIHigh recombinant protein producers emphasize citrate shuttling and beta-oxidation, linking energy with secretory capacity. C_LIO_LIATP demand maximization provides the most accurate generalizable FBA objective C_LI

systems biology↗

bioRxiv2025

Nicotinamide reverses the Warburg effect in Chinese hamster ovary cell culture

The Warburg effect, the preferential conversion of glucose-derived pyruvate to lactate despite available oxygen, is a key feature of Chinese hamster ovary (CHO) cell culture. Lactate accumulation in recombinant protein-producing cell culture is an inefficient usage of glucose, as well as being deleterious to cells. Lactate accumulation lowers culture pH, requiring base addition to maintain bioreactor pH setpoint, which subsequently leads to hyperosmolarity, adversely impacting cell growth, productivity and product quality. A key driver for the Warburg effect, and hence lactate accumulation, is the need to regenerate NAD+ consumed during glycolysis. Since oxidative phosphorylation (OXPHOS) has limited capacity to recycle NADH back to NAD+ at high glycolytic fluxes, cells rely on lactate dehydrogenase (LDH) to convert pyruvate to lactate, simultaneously regenerating NAD+ and sustaining glycolysis. Thus, providing the cells capacity to generate more NAD+ would decrease the reliance on the Warburg effect. In this study, feeding the NAD+ precursor nicotinamide (NAM) leads to reversal of the Warburg effect, inducing the "lactate shift" three days earlier in cell culture and reducing peak lactate concentration by 40%. Transcriptomic analysis further confirms this metabolic shift, with an upregulation of key mitochondrial electron transport chain genes. These results identify NAD+/NADH balance as a key regulator of the Warburg effect and demonstrate NAM supplementation as a simple, cost-effective strategy to mitigate lactate accumulation and improve metabolic efficiency in CHO cell cultures.

bioengineering↗

bioRxiv2025

A community-consensus reconstruction of Chinese Hamster metabolism enables structural systems biology analyses to decipher metabolic rewiring in lactate-free CHO cells

Genome-scale metabolic models (GEMs) are indispensable for studying and engineering cellular metabolism. Here, we present iCHO3K, a community-consensus, manually-curated reconstruction of the Chinese Hamster metabolic network. In addition to accounting for 11004 reactions associated with 3597 genes, iCHO3K includes 3489 protein structures and structural descriptors for >70% of its 7377 metabolites, enabling deeper exploration of the link between molecular structure and cellular metabolism. We used iCHO3K to contextualize transcriptomics and metabolomics data from a CHO cell line in which lactate secretion is abolished. We found the reduced glycolytic flux and enhanced TCA cycle flux were accompanied by an elevated NADH and PEP levels in these cells, consistent with experimental measurements. Leveraging iCHO3Ks structural annotations, we identified candidate binding interactions of NADH and PEP with glycolytic enzymes showing model-predicted differential flux, suggesting novel allosteric regulation associated with the observed decrease in glucose uptake and glycolysis. Overall, iCHO3K offers a valuable framework for systematic integration of omics data, improved flux predictions, and structure-guided insights, thus advancing CHO cell engineering and enhancing biomanufacturing efficiency.

systems biology↗

bioRxiv2023

Cytosolic linear DNA plasmids in Saccharomycopsis species

Some budding yeast species contain cytosolic linear DNA plasmids (also called virus-like elements, VLEs) that code for killer toxins that can kill other yeasts. The toxins are anticodon nucleases that cleave a specific tRNA in the cells being attacked, stopping translation. The best known plasmids of this type are the pGKL1/pGKL2 system of Kluyveromyces lactis. pGKL1 is a killer plasmid encoding the toxin zymocin ({gamma}-toxin) which cleaves tRNA-Glu, and pGKL2 is a helper plasmid required for replication and transcription of pGKL1. Here, we investigated similar plasmids in the genus Saccharomycopsis that were originally described in the 1980s. Saccharomycopsis has undergone an evolutionary change of its genetic code, from CUG-Leu to CUG-Ser translation, which we hypothesized could have been driven by a tRNA-cleaving toxin encoded by a cytosolic plasmid. We sequenced a three-plasmid system in S. crataegensis, consisting of apparent killer, immunity, and helper plasmids. The killer plasmid contains genes coding for putative /{beta} (chitin-binding) and {gamma} (ribonuclease) toxin subunits, but the {gamma}-toxin gene is damaged in all the isolates we examined. We inferred the sequence of the intact S. crataegensis {gamma}-toxin and expressed it in Saccharomyces cerevisiae and Kluyveromyces marxianus, but it did not cause a growth defect. We also identified free plasmids, or plasmids integrated into the nuclear genome, in nine other Saccharomycopsis species, including a case of recent interspecies transfer of a plasmid. Our results show that many yeasts in the CUG-Ser2 clade contain, or have in the past contained, plasmids related to those that carry anticodon nucleases.

evolutionary biology↗

bioRxiv2022

Regulated use of alternative Transcription Start Sites controls the production of cytosolic or mitochondrial forms of branched-chain aminotransferase in Kluyveromyces marxianus

Following a whole genome duplication (WGD) event approximately 100 million years ago, the yeast lineage from which the model Saccharomyces cerevisiae derives maintained two copies of genes where it was necessary to synthesise proteoforms with different sub-cellular localisation. In contrast, yeasts that did not undergo the WGD event have a single gene that must encode both proteoforms. We adopted an integrated in silico and experimental approach to study how this is achieved with BAT1, a gene that encodes mitochondrial and cytosolic forms of a branched chain aminotransferase (BCAT) in pre-WGD yeast such as Kluyveromyces marxianus. We determined that condition-specific regulation of alternative transcription sites gives rise to mRNA isoforms that differ at the 5end and that, when decoded, generate a mitochondrial or cytosolic proteoform. Furthermore, targeted mutants lacking specific transcription factors were generated to establish how this differentiation was regulated. As in S. cerevisiae, Gcn4 and Leu3 activated expression of the mRNA encoding the mitochondrial proteoform under conditions when branched chain amino acid synthesis was required. Unlike S. cerevisiae, however, K. marxianus lacked tight regulation of the mRNA encoding the cytosolic proteoform supporting the hypothesis that maintaining paralogous genes in post-WGD yeasts facilitated development of more sophisticated expression control mechanisms.

genetics↗

bioRxiv2018

Multiple sclerosis-associated changes in the composition and immune functions of spore-forming bacteria

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system characterized by adaptive and innate immune system dysregulation. Recent work has revealed moderate alteration of gut microbial communities in subjects with MS and in experimental, induced models. However, a mechanistic understanding linking the observed changes in the microbiota and the presence of the disease is still missing. Chloroform-resistant, spore-forming bacteria have been shown to exhibit immunomodulatory properties in vitro and in vivo, but they have not yet been characterized in the context of human disease. This study addresses the community composition and immune function of this bacterial fraction in MS. We identify MS-associated spore-forming taxa and show that their presence correlates with impaired differentiation of IL-10 secreting, regulatory T lymphocytes in-vitro. Colonization of antibiotic-treated mice with spore-forming bacteria allowed us to identify some bacterial taxa favoring IL-10+ lymphocyte differentiation and others inducing differentiation of pro-inflammatory, IFN{gamma}+ T lymphocytes. However, when fed into antibiotic-treated mice, both MS and control derived spore-forming bacteria were able to induce immunoregulatory responses.\n\nOur analysis also identified Akkermansia muciniphila as a key organism that may interact either directly or indirectly with spore-forming bacteria to exacerbate the inflammatory effects of MS-associated gut microbiota. Thus, changes in the spore-forming fraction may influence T lymphocyte-mediated inflammation in MS. This experimental approach of isolating a subset of microbiota based on its functional characteristics may be useful to investigate other microbial fractions at greater depth.\n\nImportanceDespite the rapid emergence of microbiome related studies in human diseases, few go beyond a simple description of relative taxa levels in a select group of patients. Our study integrates computational analysis with in vitro and in vivo exploration of inflammatory properties of both complete microbial communities and individual taxa, revealing novel functional associations. We specifically show that while small differences exist between the microbiomes of MS patients and healthy subjects, these differences are exacerbated in the chloroform resistant fraction. We further demonstrate that, when purified from MS patients, this fraction is associated with impaired immunomodulatory responses in vitro.

immunology↗

bioRxiv2018

Mobile genetic element-encoded hypertolerance to copper protects Staphylococcus aureus from killing by host phagocytes

Pathogens are exposed to toxic levels of copper during infection and copper tolerance may be a general virulence mechanism used by bacteria to resist host defences. In support of this, inactivation of copper-exporter genes has been found to reduce the virulence of bacterial pathogens in vivo. Here we investigate the role of copper-hypertolerance in methicillin resistant Staphylococcus aureus. We show that a copper-hypertolerance locus (copB-mco), carried on a mobile genetic element, is prevalent in a collection of invasive S. aureus strains and more widely among clonal complex 22, 30 and 398 strains. The copB and mco genes encode a copper efflux pump and a multicopper oxidase, respectively. Isogenic mutants lacking copB or mco had impaired growth in subinhibitory concentrations of copper. Transfer of a copB-mco encoding plasmid to a naive clinical isolate resulted in a gain of copper hypertolerance and enhanced bacterial survival inside primed macrophages. The copB and mco genes were upregulated within infected macrophages and their expression was dependent on the copper sensitive operon repressor CsoR. Isogenic copB and mco mutants were impaired in their ability to persist intracellularly in macrophages and were less resistant to phagocytic killing in human blood than the parent strain. The importance of copper-regulated genes in resistance to phagocytic killing was further elaborated using mutants expressing a copper-insensitive variant of CsoR. Our findings suggest that the gain of mobile genetic elements carrying copper-hypertolerance genes contributes to the evolution of virulent strains of S. aureus, better equipped to resist killing by host immune cells.

microbiology↗