Biology subjects

Tennessen, J.

Publications and source records attributed to Tennessen, J..

9 recordsLinked to original sources

bioRxiv2026

Spatial isotope tracing maps compartmentalized nutrient use across the adult fruit fly

Drosophila melanogaster is a powerful model for studying systemic metabolism. Although metabolism is compartmentalized across tissues, prior work in adult Drosophila has mostly measured it in dissected tissues rather than in situ, limiting the spatial information that can be gained. Here, we combine whole-fly mass-spectrometry imaging with stable-isotope tracing and flux modeling to quantify metabolic activities across the adult fruit fly in a spatially resolved manner. Across 68 tracer-fed Oregon-R female flies and 187,709 pixels, we map 81 metabolites onto eight annotated regions, including muscle, fat body, gut, and nervous system. Glucose labeling and fitted relative fluxes indicate higher glycolytic and tricarboxylic acid cycle turnover in thoracic muscle than in abdominal fat body; proline labels the nervous system and eye; glutamine the abdominal reproductive system and gut. Alanine carries glucose-derived carbon through the hemolymph and transfers nitrogen into glutamate. In flies bearing yorkie-driven gut tumors, alanine contribution to malate rises in gut and abdomen, and reducing gut alanine uptake lowers tumor burden. Together, this work establishes a framework for quantitative spatial metabolic analysis, showing compartmentalized nutrient use across the adult fruit fly.

genetics↗

bioRxiv2026

Tumour rewires host tryptophan metabolism to promote organism-wide immune suppression

How tumour genotype reshapes systemic metabolism to drive immune tolerance and tumour progression remains unclear. Here, we show that Pten-deficient Drosophila tumours reprogram host tryptophan metabolism, triggering systemic and local changes in immune and stromal compartments to foster tolerance. Tumour-derived nitric oxide activates the kynurenine pathway in liver-like tissue, selectively increasing the 3-hydroxykynurenine (3-HK) branch. Host 3-HK promotes tumour progression and suppresses immune function via aryl hydrocarbon receptor (AhR) signalling. These results identify the kynurenine pathway as a central tumour-host nexus and reveal how tumour genotype creates immune vulnerabilities.

cancer biology↗

bioRxiv2026

Drosophila melanogaster lactate dehydrogenase deficiency recapitulates the exercise intolerance of human glycogen storage disease type XI

Lactate dehydrogenase A (LDHA) is a key glycolytic enzyme that commonly exhibits altered expression in human diseases such as cancers and neurodegeneration, making it a valuable disease biomarker and putative therapeutic target. However, any treatment targeting LDHA will also disrupt normal metabolism, underscoring the need to investigate physiological consequences of inhibiting this enzyme. We previously established the fruit fly Drosophila melanogaster as a genetic model for studying LDH function in the context of growth, metabolism, and development. Here we expand upon those studies by investigating a serendipitous observation that Ldh mutant larvae exhibit diet-dependent lethality. Using a multiomic approach, we discovered this diet-dependent phenotype is independent of nutritional composition. Instead, Ldh mutant larvae are exercise intolerant and display reduced mobility, rendering mutant larvae sensitive to food consistency. Moreover, tissue-specific analysis reveals that LDH activity within muscle and peripheral glia are essential for larval viability raised on solid food. Intriguingly, these phenotypes mirror the pathophysiology of LDHA deficiency (Glycogen Storage Disease Type XI; GSD Type XI) in humans, where mild symptoms are exacerbated by physical exertion and environmental stress. Together, our findings further highlight the value of using Drosophila to explore the developmental and physiological consequences of Ldh inhibition. SUMMARY STATEMENTLoss of lactate dehydrogenase in Drosophila causes exercise intolerance and diet-dependent lethality, revealing conditional phenotypes that mirror those associated with human LDH-A deficiency.

developmental biology↗

bioRxiv2026

Comparative metabolomics identifies recurrent age-associated pathway remodeling across species

Aging is accompanied by widespread metabolic change, but it remains unclear which features are shared across species with different physiology, lifespan, and sampling contexts. To address this, we employed a pathway-centered comparative metabolomics framework to evaluate age-associated metabolic remodeling across wild African savanna elephant, mouse, and Drosophila melanogaster. Drosophila provided a controlled adult time course to map age-associated metabolite trajectories, while mouse and elephant plasma datasets allowed us to test whether these pathway signatures extended to mammalian aging. Adult Drosophila showed extensive metabolomic remodeling, with significant metabolites organizing into distinct temporal trajectory classes. Although individual metabolite overlap across species was limited, robust correspondence at the pathway-level overlap was observed. Pathway scores derived from Drosophila increased progressively with fly age, successfully distinguished young and old mice, and captured age-associated stratification across the elephant lifespan. Notably, lipid metabolism, particularly carnitine and fatty acid metabolism, together with nucleotide-related pathways, consistently emerged as the core features of aging across analyses. These findings suggest pathway-level metabolic remodeling is a recurrent feature of cross-species aging.

Systems Biology↗

bioRxiv2025

New alleles of D-2-hydroxyglutarate dehydrogenase enable studies of oncometabolite function in Drosophila melanogaster

D-2-hydroxyglutarate (D-2HG) is a potent oncometabolite capable of disrupting chromatin architecture, altering metabolism, and promoting cellular dedifferentiation. As a result, ectopic D-2HG accumulation induces neurometabolic disorders and promotes progression of multiple cancers. However, the disease-associated effects of ectopic D-2HG accumulation are dependent on genetic context. Specifically, neomorphic mutations in the mammalian genes Isocitrate dehydrogenase 1 (IDH1) and IDH2 result in the production of enzymes that inappropriately generate D-2HG from -ketoglutarate (KG). Within this genetic background, D-2HG acts as an oncometabolite and is associated with multiple cancers, including several diffuse gliomas. In contrast, loss-of-function mutations in the gene D-2-hydroxyglutarate dehydrogenase (D2hgdh) render cells unable to degrade D-2HG, resulting in excessive buildup of this molecule. D2hgdh mutations, however, are not generally associated with elevated cancer risk. This discrepancy raises the question as to why ectopic D-2HG accumulation in humans induces context-dependent disease outcomes. To enable such genetic studies in vivo, we generated two novel loss-of-function mutations in the Drosophila melanogaster gene D2hgdh and validated that these alleles result in ectopic D-2HG. Moreover, we observed that D2hgdh mutations induce developmental and metabolomic phenotypes indicative of elevated D-2HG accumulation. Overall, our efforts provide the Drosophila community with new mutant strains that can be used to study D-2HG function in human disease models as well as in the context of normal growth, metabolism, and physiology.

genetics↗

bioRxiv2025

Hypoxia-inducible factor 1α is required to establish the larval glycolytic program in Drosophila melanogaster

The rapid growth that occurs during Drosophila larval development requires a dramatic rewiring of central carbon metabolism to support biosynthesis. Larvae achieve this metabolic state, in part, by coordinately up-regulating the expression of genes involved in carbohydrate metabolism. The resulting metabolic program exhibits hallmark characteristics of aerobic glycolysis and establishes a physiological state that supports growth. To date, the only factor known to activate the larval glycolytic program is the Drosophila Estrogen-Related Receptor (dERR). However, dERR is dynamically regulated during the onset of this metabolic switch, indicating that other factors must be involved. Here we discover that Sima, the Drosophila ortholog of Hif1, is also essential for establishing the larval glycolytic program. Using a multi-omics approach, we demonstrate that sima mutants fail to properly activate aerobic glycolysis and die during larval development with metabolic defects that phenocopy dERR mutants. Moreover, we demonstrate that dERR and Sima/Hif1 protein accumulation is mutually dependent, as loss of either transcription factor results in decreased abundance of the other protein. Considering that the mammalian homologs of ERR and Hif1 also cooperatively regulate aerobic glycolysis in cancer cells, our findings establish the fly as a powerful genetic model for studying the interaction between these two key metabolic regulators. STRUCTURED ABSTRACTO_ST_ABSObjectivesC_ST_ABSThe rapid growth that occurs during Drosophila larval development requires a dramatic rewiring of central carbon metabolism to support biosynthesis. Larvae achieve this metabolic state, in part, by coordinately up-regulating the expression of genes involved in carbohydrate metabolism. The resulting metabolic program exhibits hallmark characteristics of aerobic glycolysis and establishes a physiological state that supports growth. To date, the only factor known to activate the larval glycolytic program is the Drosophila Estrogen-Related Receptor (dERR). However, dERR is dynamically regulated during the onset of this metabolic switch, indicating that other factors must be involved. Here we examine the possibility the Drosophila ortholog of Hypoxia inducible factor 1 (Hif1) is also required to activate the larval glycolytic program. MethodsCRISPR/Cas9 was used to generate new loss-of-function alleles in the Drosophila gene similar (sima), which encodes the sole fly ortholog of Hif1. The resulting mutant strains were analyzed using a combination of metabolomics and RNAseq for defects in carbohydrate metabolism. ResultsOur studies reveal that sima mutants fail to activate aerobic glycolysis and die during larval development with metabolic phenotypes that mimic those displayed by dERR mutants. Moreover, we demonstrate that dERR and Sima/Hif1 protein accumulation is mutually dependent, as loss of either transcription factor results in decreased abundance the other protein. ConclusionsThese findings demonstrate that Sima/HIF1 is required during embryogenesis to coordinately up-regulate carbohydrate metabolism in preparation for larval growth. Notably, our study also reveals that the Sima-dependent gene expression profile shares considerable overlap with that observed in dERR mutant, suggesting that Sima/HIF1 and dERR cooperatively regulate embryonic and larval glycolytic gene expression. HIGHLIGHTSO_LIThe Drosophila melanogaster gene similar (sima), which encodes the sole fly ortholog of Hif1, is required to up-regulate glycolysis in preparation for larval growth. C_LIO_LIsima mutant larvae exhibit severe defects in carbohydrate metabolism and die during the second larval instar. C_LIO_LIsima mutant larvae exhibit the same metabolic phenotypes as Drosophila Estrogen Related Receptor (dERR) mutants, suggesting that these two transcription factors coordinately regulate the larval glycolytic program. C_LIO_LISima/Hif1 and dERR accumulation is mutually dependent, as loss of either transcription factor results in decreased abundance of the other. C_LI

developmental biology↗

bioRxiv2024

Genomic Signatures of Microgeographic Adaptation in Anopheles coluzzii Along an Anthropogenic Gradient in Gabon

Species distributed across heterogeneous environments often evolve locally adapted populations, but understanding how these persist in the presence of homogenizing gene flow remains puzzling. In Gabon, Anopheles coluzzii, a major African malaria mosquito is found along an ecological gradient, including a sylvatic population, away of any human presence. This study identifies into the genomic signatures of local adaptation in populations from distinct environments including the urban area of Libreville, and two proximate sites 10km apart in the La Lope National Park (LLP), a village and its sylvatic neighborhood. Whole genome re-sequencing of 96 mosquitoes unveiled[~] 5.7millions high-quality single nucleotide polymorphisms. Coalescent-based demographic analyses suggest an[~] 8,000-year-old divergence between Libreville and La Lope populations, followed by a secondary contact ([~]4,000 ybp) resulting in asymmetric effective gene flow. The urban population displayed reduced effective size, evidence of inbreeding, and strong selection pressures for adaptation to urban settings, as suggested by the hard selective sweeps associated with genes involved in detoxification and insecticide resistance. In contrast, the two geographically proximate LLP populations showed larger effective sizes, and distinctive genomic differences in selective signals, notably soft-selective sweeps on the standing genetic variation. Although neutral loci and chromosomal inversions failed to discriminate between LLP populations, our findings support that microgeographic adaptation can swiftly emerge through selection on standing genetic variation despite high gene flow. This study contributes to the growing understanding of evolution of populations in heterogeneous environments amid ongoing gene flow and how major malaria mosquitoes adapt to human. SignificanceAnopheles coluzzii, a major African malaria vector, thrives from humid rainforests to dry savannahs and coastal areas. This ecological success is linked to its close association with domestic settings, with human playing significant roles in driving the recent urban evolution of this mosquito. Our research explores the assumption that these mosquitoes are strictly dependent on human habitats, by conducting whole-genome sequencing on An. coluzzii specimens from urban, rural, and sylvatic sites in Gabon. We found that urban mosquitoes show de novo genetic signatures of human-driven vector control, while rural and sylvatic mosquitoes exhibit distinctive genetic evidence of local adaptations derived from standing genetic variation. Understanding adaptation mechanisms of this mosquito is therefore crucial to predict evolution of vector control strategies.

evolutionary biology↗

bioRxiv2023

Wolbachia is a nutritional symbiont

The intracellular bacterium Wolbachia is a common symbiont of many arthropods and nematodes, well studied for its impacts on host reproductive biology. However, its broad success as a vertically transmitted infection cannot be attributed to manipulations of host reproduction alone. Using the Drosophila melanogaster model and their natively associated Wolbachia strain "wMel", we show that Wolbachia infection supports fly development and buffers against nutritional stress. Wolbachia infection across several fly genotypes and a range of nutrient conditions resulted in reduced pupal mortality, increased adult emergence, and larger size. We determined that the exogenous supplementation of pyrimidines partially rescued developmental phenotypes in the Wolbachia-free flies, and that Wolbachia titers were responsive to reduced gene expression of the flys de novo pyrimidine synthesis pathway. In parallel, transcriptomic and metabolomic analyses indicated that Wolbachia impacts larval biology far beyond pyrimidine metabolism. Wolbachia-infected larvae had strong signatures of shifts in glutathione and mitochondrial metabolism, plus significant changes in the expression of key developmental regulators including Notch, the insulin receptor (lnR), and the juvenile hormone receptor Methoprene-tolerant (Met). We propose that Wolbachia acts as a beneficial symbiont to support fly development and enhance host fitness, especially during periods of nutrient stress. SIGNIFICANCEWolbachia is a bacterial symbiont of arthropods and nematodes, well described for its manipulations of arthropod reproduction. However, many have theorized there must be more to this symbiosis, even in well-studied Wolbachia-host relationships such as with Drosophila. Reproductive impacts alone cannot explain the success and ubiquity of this bacterium. Here, we use Drosophila melanogaster and their native Wolbachia infections to show that Wolbachia supports fly development and significantly buffers flies against nutritional stress. These developmental advantages might help explain the ubiquity of Wolbachia infections.

developmental biology↗

bioRxiv2022

NMNAT2 is the major NAD+ provider for vesicular glycolysis generating on-board energy for fast axonal transport cargos

BackgroundBioenergetic maladaptations and axonopathy are often found in the early stages of neurodegeneration. Nicotinamide adenine dinucleotide (NAD), an essential cofactor for energy metabolism, is mainly synthesized by Nicotinamide mononucleotide adenylyl transferase 2 (NMNAT2) in CNS neurons. NMNAT2 mRNA levels are reduced in the brains of Alzheimers, Parkinsons and Huntingtons disease. Here we addressed whether NMNAT2 is required for axonal health of cortical glutamatergic neurons, whose far-projecting axons are vulnerable to neurodegenerative conditions. We also tested if NMNAT2 maintains axonal health by ensuring proper axonal ATP levels for axonal transport, a critical function of axons. MethodsWe generated mouse and cultured neuron models to determine the impact of NMNAT2 loss from cortical glutamatergic neurons on axonal transport, energetic metabolism, and morphological integrity. In addition, we determined if exogenous NAD supplementation or inhibiting NAD hydrolase sterile alpha and TIR motif-containing protein 1 (SARM1) prevented axonal deficits caused by NMNAT2 loss. Our study used a combination of genetic, molecular biology, immunohistochemistry, biochemistry, fluorescent time-lapse imaging, live imaging with optical sensors, and anti-sense oligos application. ResultsWe provide in vivo evidence that NMNAT2 in cortical glutamatergic neurons is required for axonal survival. Using in vivo and in vitro studies we demonstrate that NMNAT2 protects axons by ensuring the proper NAD-redox potential in distal axons of cortical neurons to support glycolysis on vesicular cargos, thus ensuring "onboard" ATP production fueling axonal transport. Exogenous NAD+ supplementation to NMNAT2 KO cortical neurons restores glycolysis and resumes fast axonal transport. Finally, we demonstrate both in vitro and in vivo that reducing the activity of SARM1, an NAD degradation enzyme, can reduce axonal transport deficits and suppress axon degeneration in NMNAT2 KO neurons. ConclusionNMNAT2 ensures axonal health by maintaining NAD redox potential in distal axons to ensure efficient vesicular glycolysis required for fast axonal transport.

neuroscience↗