Biology and Life Sciences

Abstract: DNA/cell mass homeostasis is a pervasive feature of living organisms. As the cell grows in response to nutrient availability, it must duplicate each chromosome once and only once each division cycle. Across the eukaryote Tree of Life, cells differ in their sizes in a manner that depends directly on the amount of DNA they harbor, what has been termed the “nucleotypic effect”: cell size expands or contracts as DNA content increases or decreases. In eukaryotes, any deviation from DNA/mass homeostasis results in the deregulation of the developmental program and the initiation of carcinogenesis and other genetic pathologies. In bacteria, deviation from, or perturbation of, DNA/mass homeostasis alters important physiological features such as the cell cycle timing of DNA replication initiation and the co-ordination of initiation with replication termination and cell division. In prokaryotes, the timing of initiation occurs at a relatively constant and growth rate invariant mass, termed the initiation mass (Mi), and depends strictly on DNA replication fork rates and membrane biogenesis. Complex “machines”, frequently referred to as hyperstructures or factories, mediate the phase transitions that define the different periods of the bacterial cell cycle. The following will examine how the cell size and DNA/mass homeostasis maintains a balance between replication initiation and elongation, that gate the phase transitions that organize the cell cycle in time and space.

Abstract: The establishment of a reference population for genomic selection in Korean beef cattle is an ongoing process. There is a high likelihood of sex-specific differences in the composition of the reference and test populations. This study evaluates the accuracy of Genomic Estimated Breeding Values (GEBVs) for carcass traits in Hanwoo cattle, specifically investigating the efficacy of cow-based reference populations. The effectiveness of genomic selection (GS) is heavily dependent on the composition and size of the reference population. Utilizing genotype data from a Hanwoo 50k SNP chip and phenotypic data from 19,168 steers and 6,233 cows, the study estimated GEBV accuracies for carcass weight (CWT), eye muscle area (EMA), backfat thickness (BF), and marbling score (MS) using the GBLUP method. Results demonstrate that steer-based reference populations achieved the highest accuracy (0.64–0.88), averaging 0.78, likely due to standardized management and higher trait heritability (0.39–0.51) compared to cows. In contrast, cow-based reference populations exhibited prediction accuracies (0.55–0.75) in four traits using adjusted residual phenotype, averaging 0.64, but remained highly practical alternatives. While growth traits (CWT and EMA) showed significant bias in cross-sex predictions, fat deposition traits (BF and MS) remained stable across sexes. The study concludes that although steer-based populations provide optimal accuracy, incorporating cows into the reference population is strategically vital in Hanwoo.

Abstract: This study aimed to characterize metabolomic changes in the eye lens of senescence-accelerated OXYS rats in comparison with control Wistar rats, and to identify biochemical shifts associated with genotype, age, and cataract progression. Cataract severity was clinically graded. Rats' lenses were analyzed using quantitative ¹H NMR spectroscopy at 3.6 and approximately 4.5 months of age. A total of 43 metabolites were quantified. We found that at 3.6 months of age, OXYS lenses exhibited a significant accumulation of 17 metabolites, primarily amino acids, compared to Wistar rats, suggesting an imbalance between amino acid uptake and crystallin biosynthesis. However, by 4.5 months, OXYS lenses exhibited rapid metabolic changes characterized by significant decreases in amino acid, glucose, and key energy/antioxidant markers, including NAD, adenylate energy charge, and hypotaurine. Clinical cataract grade (Grade 2 vs. 3) had a negligible impact on the overall metabolomic profile. Our results indicate that profound metabolic reorganization, including an initial amino acid excess followed by energy and antioxidant depletion, precedes the morphological manifestation of cataracts in OXYS rats. We suggest that a biochemical "point of no return" occurs early in cataractogenesis, while subsequent increase in lens opacification is a secondary consequence of preexisting metabolic disturbances.

Abstract:

Leukocyte recruitment from blood into tissues involves sequential adhesive steps, including rolling and integrin-dependent arrest. The integrin VLA-4 is known to mediate firm adhesion, but can also support rolling. CD44–hyaluronan interactions have also been implicated in leukocyte rolling. Here, we used parallel-plate flow chamber assays to compare the contributions of CD44 and VLA-4 to monocyte rolling on different cellular monolayers. Monocytoid WEHI 78/24 cells rolled and adhered through CD44 on hyaluronan-presenting ECV304 monolayers, whereas VLA-4 dominated adhesion on endothelial monolayers expressing functional VCAM-1. Primary human monocytes showed similar CD44-dependent rolling on ECV304 monolayers. Blocking CD44, adding soluble hyaluronan, or removing surface hyaluronan with hyaluronidase reduced rolling and adhesion. These results show that CD44 can support monocyte rolling when VLA-4/VCAM-1 adhesion is not the dominant interaction. This cell-based flow model distinguishes CD44/hyaluronan-mediated rolling from VLA-4/VCAM-1-rolling and may help analyze monocyte rolling on hyaluronan, including tumor-derived monolayers.

Abstract: Rare diseases, though individually uncommon, collectively represent a major global health challenge, affecting millions worldwide and increasingly recognized in India as a significant contributor to pediatric and adult morbidity. Cystic fibrosis (CF), a multisystem autosomal recessive disorder caused by pathogenic variants in the Cystic Fibrosis Transmembrane Conductance Regulator (\textit{CFTR}) gene, exemplifies this burden, with delayed diagnosis and diverse mutational spectra complicating clinical management in South Asian populations. To advance rare disease genomics, quantitative analysis of CFTR sequences across multiple species is essential, as evolutionary conservation highlights residues and motifs critical for channel function, while divergence reveals lineage-specific adaptations relevant to disease mechanisms. In the present study, we performed integrative analyses encompassing amino acid composition, sequence homology, frequency-dominant residue patterns, hydropathy-based n‑gram distributions, hydropathy profile continuity, and intrinsic disorder architectures across various CFTR sequences from multiple species. The quantitative signatures derived from amino acid composition, sequence homology, hydropathy-based n‑grams, hydropathy profiles, and intrinsic disorder analyses carry significant translational impact, as they provide a unified framework for identifying conserved motifs, resolving disorder-prone domains, and guiding the precise mapping of pathogenic mutations and their functional consequences. Collectively, our findings demonstrate how cross-species quantitative protein analysis of CFTR bridges evolutionary biology with clinical investigation, providing translational insights that strengthen rare disease research and therapeutic development in cystic fibrosis.

Abstract: Poxviruses are large double-stranded DNA (dsDNA) viruses that cause important human and animal diseases, including smallpox and mpox. Poxviruses have also been identified in diverse bat populations; however, their potential for zoonotic transmission and adaptation to other mammalian hosts remains poorly understood. Poxviruses encode numerous immunomodulatory proteins that contribute to virulence, immune evasion, and host range. In this study, we performed a comparative genomic analysis of two bat-associated poxviruses belonging to the genus Vespertilionpoxvirus: hypsugopox virus (HYPV) and eptesipox virus (EPTV). We identified 24 and three previously unannotated putative open reading frames (ORFs) in HYPV, and EPTV, respectively, substantially expanding the predicted coding capacity of these viruses. Comparative analyses further revealed gene duplication and fragmentation events affecting several virulence and host range factors, as well as other unusual genomic features, including the presence of two divergent E3L homologs in EPTV. Together, our findings provide new insights into the genome evolution and potential host adaptation of bat-associated poxviruses and establish a foundation for future functional studies of Vespertilionpoxvirus biology, host-virus interactions, and zoonotic potential.

Abstract: Metabolomics is a powerful approach for monitoring metabolic effects in a particular situation by qualitatively or quantitatively analyzing metabolites related to specific physiological or pathological responses within a biological process. Rapeseed is a major source of vegetable oil and contains a wide variety of metabolites. Recent advances, particularly the integration of metabolomics with other omics approaches, now allow us not only to obtain a comprehensive overview but also to perform detailed analyses of key metabolites that respond to specific conditions. In this review, we summarize recent progresses in rapeseed metabolomics study, introduce the key metabolites uncovered by this approach, and discuss those associated with growth & development, and abiotic and biotic stresses, including macronutrient availability, temperature, water stress, salt stress, and cadmium toxicity. Future perspectives and current challenges in metabolomics are also discussed, along with its potential for breeding applications aimed at developing new rapeseed varieties with stable, high-yield, and high-quality traits.

Abstract: Soil salinization severely limits alfalfa productivity; however, the molecular mechanisms governing cultivar-specific differences in salt tolerance remain largely unclear. In this study, two alfalfa cultivars (Zhongmu No.3 and WL440-HQ) were exposed to 200 mM NaCl stress, followed by integrated transcriptome sequencing, weighted gene co-expression network analysis (WGCNA), and functional validation. In total, 3,517 salt-responsive differentially expressed genes (DEGs) were identified, including 795 shared DEGs and cultivar-specific DEGs (1,336 in Zhongmu No.3 and 1,386 in WL440-HQ). GO and KEGG enrichment revealed conserved stress-response pathways, including flavonoid biosynthesis and starch and sucrose metabolism, as well as cultivar-specific patterns, with Zhongmu No.3 strongly enriched in stimulus-responsive genes. WGCNA further identified phenotype-related modules and core hub genes, notably MsWRKY22 and MsPSK3. Overexpression of MsPSK3 enhanced salt-alkali tolerance in alfalfa by activating antioxidant systems. Dual-luciferase and yeast one-hybrid (Y1H) assays verified that MsMYC2 directly binds to and activates the MsPSK3 promoter. This study reveals the molecular regulatory network underlying alfalfa responses to salt–alkali stress and provides key candidate genes for breeding salt-tolerant alfalfa varieties.

Abstract: Generally, cancer is responsible for nearly every sixth death worldwide. Early cancer revelation can provide successful and low-cost treatment of cancer, enhancing survival rates of cancer patients. This explains the key importance of development of novel highly sensitive systems for revelation of cancers in humans. Ribonucleic acids (RNAs) of several different types (microRNAs, circular RNAs, and small nucleolar RNAs) represent promising cancer biomarkers. At the same time, nanoribbon biosensors allow one to detect cancer-associated RNAs at ultra-low concentrations. Here we focus at experimental results on the detection of cancer-associated RNAs in human plasma with our nanoribbon biosensor, demonstrating promising capabilities of this nanotechnology-based device as a base of highly efficient diagnostic screening platform for early diagnosis of cancers in humans.

Abstract: Alzheimer’s disease (AD) is more common in women than men and the risk of AD increases markedly during and after the menopausal transition. Although a role for estrogen deficiency is well studied, recent reports have revealed the pivotal but under-recognized contribution of follicle-stimulating hormone (FSH) in mediating neurodegenerative risk. In this review, we integrate current understanding of reproductive aging, AD pathobiology, and sex differences with a specific emphasis on endocrine, metabolic and inflammatory processes. FSH increases during reproductive aging and has mechanistic connections to several canonical molecular pathways that are altered in AD. This includes signaling through C/EBPβ-δ-secretase, mitochondria, glucose metabolism, and the autophagic/lysosomal clearance pathway. The convergence of these processes appears to underlie aspects of amyloid-β (Aβ) accumulation, tau pathology, and chronic neuroinflammation. FSH also modulates apolipoprotein biology (e.g., ApoE) by impacting lipid metabolism, protein lipidation, and clearance, which in turn affects Aβ kinetics and neuroinflammation in an ApoE isoform-specific manner. In addition, reproductive aging is associated with changes in vascular health and permeability, blood-brain barrier function, and immunometabolic processes that may drive neurodegenerative risk. Critically, these early upstream events drive disease risk before the onset of the more classical pathological features, which may shift our current perception of Aβ and tau as causes of AD to instead be consequences of upstream failure. Overall, this review provides mechanistic insight into the role of FSH and its downstream signaling pathways in neurodegeneration. As such, modulating FSH signaling and downstream pathways is a promising and mechanistically supported therapeutic strategy for reducing AD risk in women.

Abstract: Honeybee population decline poses a serious threat to global biodiversity and agricultural productivity, underscoring the need for continuous and non-invasive hive monitoring solutions. In particular, early detection of queen absence is critical for maintaining colony viability. This study investigates the effectiveness of machine learning and deep learning models for acoustic-based queen-presence detection using short-duration hive audio recordings. Audio data collected from multiple sources were processed to extract spectrogram, Mel-spectrogram, and Mel-frequency cepstral coefficient features, which were evaluated using classical ML classifiers and convolutional neural networks. Experimental results indicate that MFCC-based representations consistently outperform spectrogram-based features across segment lengths, achieving higher accuracy and greater stability. The best performance was obtained with Mel features using convolutional neural networks for short segments and gradient-boosted models for longer windows. These findings demonstrate that brief acoustic segments are sufficient for reliable classification, supporting real-time monitoring under noisy field conditions. The proposed approach offers a scalable and low-cost framework for precision beekeeping and contributes to sustainable beekeeping through early, automated anomaly detection. The proposed framework supports real-time, low-cost deployment scenarios, enabling scalable precision apiculture solutions.

Abstract: Pathogenicity islands (PAIs) are regions of bacterial genomes that harbor genes encoding virulence factors. Identifying molecules that enhance pathogenicity is crucial for understanding the mechanisms pathogens employ to cause disease and their evolution. Corynebacterium pseudotuberculosis (C. pseudotuberculosis) is a pathogenic micro-organism that causes caseous lymphadenitis (CLA) in sheep and goats. Despite its prevalence in Mexico, its genetic material has not been analyzed for virulence factors acquired through horizontal gene transfer. Therefore, the objective of this study was to analyze the complete genome of C. pseudotuberculosis strains of Mexican origin to identify genes hosted in PAIs. Seventeen genomes were sequenced using Illumina technology. GIPSY software was used to identify the coordinates of the PAIs, and a positive selection analysis was performed. All genomes corresponded to C. pseudotuberculosis biovar ovis, and fourteen regions harboring virulence factors were identified. Additionally, five coding sequences with mutations under positive selection were identified. A comparative genetic study was conducted between the new Mexican strains and previously reported strains, using whole-genome multilocus sequence typing (wgMLST) to determine phylogenetic relationships. This work provides the complete genetic repertoire of 17 new strains and identifies 51 genes that could serve as targets in future studies.

Abstract: Functional fermented beverages represent promising dietary tools for modulating nutrient-responsive pathways and intestinal homeostasis. The probiotic strain Lacticaseibacillus paracasei subsp. paracasei F19 (F19) has demonstrated exceptional resilience in technologically harsh environments, including high-hopped beers, acidic dairy matrices, and polyphenol-rich fruit substrates. Evidence from multi-omics analyses indicates that F19 activates hop- and acid-resistance systems while maintaining metabolic functions responsible for folate biosynthesis, short-chain fatty acid production, and the generation of bioactive volatiles. These metabolites participate in host-directed mechanisms, including the upregulation of the vitamin D receptor (VDR), modulation of autophagy-related genes such as ATG16L1, and attenuation of inflammatory signaling. Complementary studies using red pitaya (Hylocereus sp.) fermented with F19 and Bifidobacterium animalis subsp. lactis BB-12 further demonstrate increased VDR and CAMP expression, reduced CYP24A1, and the enrichment of anti-inflammatory flavonoids such as rutin and quercetin. Collectively, these findings support the concept of a probiotic paradox, in which environmental stressors do not suppress probiotic function but instead enhance genetic, metabolic, and host-interactive capacities. F19 thus emerges as a compelling candidate for the development of functional fermented foods aimed at improving epithelial barrier integrity, modulating immune responses, and supporting microbiota equilibrium, with translational potential for managing inflammatory and nutrient-responsive intestinal disorders.

Abstract: Purpose: Next-generation sequencing (NGS) is routinely used in the diagnostic workup of neurological diseases, enabling systematic screening for SMA with tailored bioinformatic tools, further enhancing diagnostic speed and accuracy. Methods: We leveraged SMNCopyNumberCaller, SMAca, and SMAFinder in our NGS cohort (n = 3493), including 74 MLPA-validated SMA cases (one compound heterozygous) in the exome dataset. Putative SMA cases were validated using PCR-RFLP and MLPA. Results: With default settings of SMA Finder in exome cohort (n = 2437), 16.4% of samples were uncallable including 40 known SMA cases. Lowering read thresholds markedly improved callability and identified 71/73 known SMA cases, two cases remaining uncallable. SMAca correctly detected 73/73 SMA cases. Both tools had a positive predictive value of 100% and identified two missed cases (DM1, MND), subsequently molecularly confirmed. After inclusion of correction value to scale factor, SMAca showed high concordance with MLPA for SMN2 copy number estimation in SMA cases. Carrier frequencies were estimated as 1:36 and 1:47, in genome and exome respectively. Using SMNCopyNumberCaller, we provided detailed SMN profiling in a Turkish genome cohort (n = 1056). Conclusions: NGS-based SMN analysis enables robust detection of SMA and supports systematic cohort screening to identify missed cases.

Abstract:

Background: The local twitch response (LTR) elicited during ultrasound-guided fascial hydrorelease (FHR) is conventionally attributed to dysfunctional motor endplates. However, in a related observational paper under concurrent submission, 89/89 evaluable archived LTR events were observed within stacking fascia at sites incompatible with direct endplate excitation. Hypothesis: We propose the Fascial Capacitor Model: stacking fascia functions as a multilayer biological capacitor in which collagen sublayers act as electrodes and the interposed densified hyaluronic-acid (HA)-rich loose layer acts as the dielectric, with the LTR reinterpreted as a transient electrophysiological discharge when a needle bridges its layers. This biophysical model is explicitly grounded in the established molecular and histological architecture of human deep fascia. Supporting evidence: Each premise is independently supported by primary literature from at least eight research lines spanning roughly seventy years. Voltage gap: The apparent gap between estimated bulk discharge voltages and motor neuron threshold is resolved by reconsidering needle-tip geometry and stimulation modality, anchored by the ±6 V triboelectric measurements of Ouyang et al. (2022). Implications: The model is the immediate-phase complement to the Fascial Memory Reset Hypothesis (Int J Mol Sci 2026, 27, 3720), explains intra-procedural symptom relief, and yields falsifiable predictions. A direct empirical validation programme using insulating-needle SEA recording is in preparation at the corresponding author’s institution.

Abstract: Time-restricted feeding (TRF) has emerged as a promising intervention to improve metabolic health and promote healthy aging, yet the cellular mechanisms underlying its effects remain incompletely understood. Here, we applied imaging-based and quantitative cellular analyses to investigate how TRF modulates aging-associated and neurodegeneration-related phenotypes in vitro. Human fibroblasts and AC16 cardiomyocytes were used as models of cellular aging, alongside fibroblast-based models of neurodegeneration. TRF was simulated through cyclic nutrient availability, and cellular responses were evaluated using microscopy-based assessment of cellular morphology, senescence-associated features, metabolic state, and circadian rhythm-associated gene expression dynamics. Imaging analyses demonstrated that TRF modulated key hallmarks of cellular senescence, including changes in cell morphology and intracellular organization, consistent with enhanced cellular resilience and altered metabolic adaptation. In AC16 cardiomyocytes, TRF influenced aging-associated cellular phenotypes, indicating that its effects extend beyond proliferative cell systems to cardiac-relevant models. In neurodegeneration-associated fibroblast models, TRF altered disease-related cellular signatures and stress-associated phenotypes, supporting a potential protective role in neurodegenerative conditions. Quantitative analyses further revealed significant TRF-induced changes in circadian rhythm characteristics across all models, including altered oscillatory amplitude, supporting a mechanistic link between nutrient timing and cellular timekeeping. Together, these findings demonstrate that TRF induces measurable changes in cellular architecture and circadian regulation associated with improved aging- and neurodegeneration-related phenotypes. This work highlights the utility of imaging-based approaches for investigating the spatiotemporal cellular effects of metabolic interventions and supports TRF as a potential therapeutic strategy for age-associated diseases.

Abstract: 2,2′,4,4′-Tetrabromodiphenyl ether (BDE-47) is a persistent organic pollutant detected in coastal environments. The effects of BDE-47 on mangrove plants at the molecular and histological levels remain elusive. In this study, seedlings of the man-grove species Avicennia marina were exposed to BDE-47 at concentrations of 0, 1 and 10 ng L-1 for 20 days under hydroponic conditions. Leaf growth parameters, anatomical structures, and transcriptomic profiles were examined. At 1 ng L-1 BDE-47, no signif-icant changes were observed in leaf growth or vascular tissue morphology. However, transcriptome analysis showed significant enrichment of differentially expressed genes in the linoleic acid metabolism pathway, indicating that A. marina initiates early stress perception via enhanced stress perception and signal transduction, trigger adaptive defense responses to low-level BDE-47 exposure, and circumvent growth inhibition. At 10 ng L-1 BDE-47, leaf area, width, length, and fresh weight were all reduced. In addi-tion, histological examination revealed vascular bundle sheath atrophy, impaired xy-lem and phloem development, reduced parenchyma cell diameter, and a decreased proportion of intercellular space. Transcriptomic analysis at 10 ng L^-1 exposure identi-fied significant enrichment of differentially expressed genes in the circadian rhythm and spliceosome pathways, indicating that the pollutant's toxicity has progressed from local metabolic disruption to perturbation of the plant's core regulatory network. Overall, our findings reveal distinct response patterns of A. marina leaves to BDE-47 exposure at environmentally relevant concentrations, initially elucidate the adaptive defense mechanism and underlying molecular basis of toxic effects in mangrove plants under low-concentration BDE-47 exposure, and provide critical scientific support for the ecological risk assessment and conservation of coastal mangrove wetlands.

Abstract: Aging causes exhaustion of stem cells (SCs), loss of regenerative potential, and thereby makes them susceptible to age-related diseases (ARDs), known as cellular senescence. Senescent stem cells (SenSCs) secrete Senescence-Associated Secretory Phenotypes (SASPs) that synergistically exacerbate inflammation. Alongside this, they secrete Senescence-Derived extracellular vesicles (SenEVs) that carry a diverse array of molecules that transmit senescence-inducing signals to distant cells and tissues throughout the body, intensifying the detrimental effects of ageing and fostering a pro-tumorigenic microenvironment (PTME). In this review, we comprehensively assess these EVs, their distinct microRNA (miRNA) landscape, protein cargo, including extracellular matrix (ECM) remodeling enzymes and inflammatory cytokines, lipid profiles, and metabolomic signatures. Critically, we elucidate how SenEVs drive systemic ageing through paracrine transmission of senescence, impairing tissue regeneration by propagating oxidative stress, disrupting stem cell niches, and contributing to organ-specific ageing. Furthermore, we discussed their role as pro-cancer factors by remodeling the tumor microenvironment (TME), as they carry oncogenic miR-21 and miR-34a, which promote immune evasion and facilitate metastatic spread. Given their pervasive influence, SenEVs offer significant therapeutic opportunities, ranging from biomarkers of biological ageing to strategies to block harmful EVs and to engineer therapeutic EVs for targeted delivery. Future directions on SenEV research should focus on standardization, single-cell EV biology, organ-specific EV mapping, multi-omics integration, and AI-driven research. This integrated perspective underscores the profound clinical and global relevance of SenEVs as innovative targets for combating cancer and ARDs.

Abstract:

Corydalis ophiocarpa is a medicinally valuable plant, noted for its abundant alkaloid content. Despite its significance, the mitochondrial genome of this plant has not been characterized, which impedes both the phylogenetic understanding within the Corydalis genus and the comprehension of its full genetic potential. In this research, we have successfully assembled the complete mitogenome of C. ophiocarpa by employing a hybrid method that integrates Oxford Nanopore long reads with Illumina short reads. The assembled genome forms a circular structure of 600,064 bp, with a GC content of 46.49%, and includes 63 genes, comprising 40 unique protein-coding genes (PCGs), 20 tRNAs, and three rRNAs. Through assembly and coverage analysis, we identified a 6,383 bp forward repeat associated with a contig having approximately double the depth, indicating a repeat-mediated multipartite structure where the main circle may coexist with two smaller subgenomic forms. We discovered 775 C-to-U RNA editing sites across the 40 PCGs, with 95.4% being non-synonymous and favoring hydrophobic amino acid substitutions, particularly in Complex I subunits. Furthermore, we identified sixteen mt plastid DNA fragments constituting 2.43% of the mitogenome, a proportion more than double that found in the closely related C. saxicola. Phylogenetic analysis confirms that C. ophiocarpa is most closely related to C. saxicola, with C. pauciovulata as another close relative. This study presents the first complete mitogenome of C. ophiocarpa, providing a genomic basis for investigating the relationships between mt genome structure, post-transcriptional regulation, and energy-intensive specialized metabolism in the Corydalis genus.

Abstract: The emergence of the eukaryotic cell is regarded as a pivotal transition in the history of life on Earth. However, mounting evidence suggests eukaryogenesis was a specific, accidental event sparked by a syntrophic symbiosis between an Asgard archaeon and a bacterial endosymbiont. This prompts a fundamental counterfactual question: what if this symbiosis never occurred? The prevailing assumption is that life would remain perpetually microbial, constrained by the bioenergetic limits of prokaryotic cells. This article challenges that view by exploring the evolutionary potential of a unique group of bacteria: giant sulfur bacteria. These bacteria, driven by powerful selection pressure to bridge spatially separated pools of hydrogen sulfide and oxygen, have independently evolved remarkable sizes and different forms of complexity, including a form of eukaryote-like compartmentalization in Thiomargarita magnifica. Through the analysis of their novel bioenergetic solutions and conceptual modelling of an alternative evolutionary history, I propose that in an eukaryote-free world, giant sulfur bacteria represent a plausible starting point for the de novo evolution of complex, multicellular life. This thought experiment, albeit extremely speculative, offers new understanding of mechanisms of gaining complexity and could be useful for the analysis of the actual eukaryogenesis event, as well for the modelling of life complexity in astrobiological settings.