npj Microgravity

Long-duration spaceflight may alter social cognition, yet the underlying biological mechanisms remain unclear. Emotion Recognition Task (ERT) performance remains stable during typical 6-month International Space Station (ISS) missions but declines markedly during the 340-day NASA Twins Study, suggesting duration-dependent vulnerability. Here, we propose the Von Economo Neuron (VEN) Fatigue Hypothesis, which posits that microgravity increases demand on VEN-associated social cognitive networks, eliciting adaptive myelination during shorter missions before compensatory mechanisms fail with prolonged exposure. To evaluate this hypothesis, we integrated evidence from rodent, human cortical organoid, astronaut plasma proteomic, and neuroimaging datasets. ISS-flown rodent frontal cortex demonstrated increased expression of myelination-related genes, while spaceflown cortical organoids exhibited changes consistent with oligodendrocyte remodeling. Astronaut plasma transcriptomics identified reproducible alterations in VEN-associated and myelination-related proteins across independent missions, and resting-state fMRI revealed transient changes in frontal insula connectivity following long-duration spaceflight. Together, these findings provide convergent evidence supporting the VEN Fatigue Hypothesis and identify adaptive myelination and VEN-associated network remodeling as candidate mechanisms underlying duration-dependent changes in social cognition during long-duration spaceflight.

Human deep-space missions face bone-kidney risks that cannot be extrapolated from six-month ISS data. We built a 12-state Ca-bone-urine-stone mechanistic ODE model and jointly calibrated its 11 physiological parameters on eight ISS targets by Bayesian identification (M0 base = 19-D; M1 extension adds a GCR-bone coupling term for parsimony testing only), then propagated the M0 posterior to four environments (ISS, Lunar subsurface, Lunar surface, Mars). Lumbar-lower BMD loss increases with mission duration and partial-gravity unloading (ISS 180 d -4.83% -> Mars 730 d -12.15%; 2^3 factorial: duration 82.9%, gravity 12.5%, GCR main effect ~ 0), whereas stone rate follows the opposite gradient (ISS 16.1 vs Mars 13.1 per 1000 person-years), reflecting weakened partial-gravity bone resorption alongside residual urinary chemistry changes. The dominant pathway thus shifts from bone-centric on the ISS to kidney-centric on Mars, where residual urinary-chemistry changes-not bone resorption-drive stone risk. The direct GCR-bone coupling term is unidentifiable at current ISS doses (DeltaWAIC = +0.0076 +/- 0.126 SE), so M0 is retained as the main inference model. Bisphosphonates provide >=84% BMD protection but leave a urinary-chemistry residual, so bisphosphonate monotherapy would underestimate Mars stone risk; potassium-magnesium-citrate combinations (RRR_RSS 51%) should therefore be added to deep-space countermeasures. A Lunar-surface 365-day mission is the earliest environment on the NASA roadmap to cross a composite RED threshold. That profile differs from the regolith-shielded 180-day case in both cumulative GCR (~69x) and duration (2x), so a shielding-specific effect cannot be isolated here; forcing the GCR coupling terms to zero leaves all four composite tiers unchanged (0/4, Supp S24), and the shielded 180-day profile is YELLOW rather than GREEN. Independent hold-out validation (Culliton 2025 60-day HDT-bedrest RCT, n=8 control arm of n=24 total) supports the M0 posterior predictive distribution on the lumbar-BMD sub-scope.

Current planetary protection approaches rely heavily on spore-based tests developed for Mars missions and may not adequately assess contamination risks for icy ocean worlds such as Europa. We developed a genome-based framework combining deep shotgun metagenomics and supervised machine learning to predict survival-relevant microbial traits in ESA JUICE launch-site cleanrooms. From 183 genome bins, 25 representative genomes were analyzed for traits including cryotolerance, desiccation tolerance, salt resilience, anaerobic metabolism, autotrophy, and sporulation. Several skin-associated microbes carried multiple relevant traits, and some appeared actively replicating. A broader meta-analysis of 1,868 genomes showed that trait profiles vary strongly within taxa, demonstrating that taxonomy alone is insufficient for risk assessment. This framework complements current planetary protection assays, helps to predict how microbes would survive in a new biotope, and supports functional, risk-informed contamination monitoring for future space missions.

Fungal contamination poses a growing threat to spacecraft integrity, crew health, and planetary protection efforts. We describe a scalable and interpretable pipeline for identifying fungi with adaptation potential to spaceflight-associated stress conditions such as extreme temperatures, radiation levels, etc., and pathogenicity risks. Starting with proteins known to confer stress resistance, we identify orthologs across over fifteen hundred fungal species and evaluate their contamination potential via comparative proteome analysis. Our pipeline integrates proteins with known functional inference, cross-database proteome matching, and identity-based scoring to generate a ranked list of fungal species of concern. We apply this approach to detections from spacecraft assembly facilities, highlighting species with combined stress-tolerance and pathogenic potential. This study establishes a foundation for future AI-based risk assessments that can scale to orders of magnitude more fungal species, thus laying the foundation for systematic identification and assessment of fungal contaminants with potential adaptation and pathogenicity risks in spaceflight environments, thereby supporting contamination control strategies for future space missions. We also present an interactive visual online tool for researchers to trivially check the contamination potential of species in their own samples.

Despite the well-known health risks of neutron exposures, key gaps remain in understanding neutron-induced molecular responses and identifying reliable biodosimetric markers that distinguish neutrons from photon exposure. We provide the first genome-wide analysis of the human blood transcriptional response to an accelerator-derived fission-like spectrum of neutrons versus photons, evaluating transcriptomic relative biological effectiveness (RBE) and radiation quality-discriminating gene signatures. Whole blood from healthy donors was irradiated ex vivo with X-rays (140 kV, 0-4 Gy, n = 3) or neutrons (0.1-8 MeV, 0-1 Gy, n = 2), incubated for 6 h or 24 h, and processed for RNA sequencing from peripheral blood mononuclear cells (PBMCs). Neutrons were markedly more potent than X-rays at inducing differentially expressed genes (DEGs) at equal doses, showing a peak response 6 h post-irradiation followed by a decline. In contrast, X-rays caused a continuous increase in DEGs up to 24 h (neutrons vs. X-rays at 1 Gy: 1,449 vs. 121 DEGs at 6 h; 996 vs. 621 DEGs at 24 h). A universal p53-centered 34-gene signature, including FDXR, EDA2R, GADD45A, and ZMAT3, showed highly monotonic dose responses (Spearman correlation coefficient {approx} 1) across donors, radiation qualities, and timepoints. Additionally, difference-in-differences analysis identified radiation quality-discriminating genes only at 6 h, with transcriptional convergence observed by 24 h, suggesting a very narrow time window for biodosimetric differentiation. We identified a neutron-specific gene signature driven by cGAS-STING-NF-{kappa}B signaling (RELB, NFKB1, C3, MALAT1) and suppression of B-cell and myeloid identity genes (IGHD, TCL1A, CLEC7A, TLR2), defining a biologically coherent neutron quality index with distinct immunomodulatory effects. For the first time, we assessed neutron RBEs at the gene, pathway, and global transcriptomic levels in a human blood model, reporting a global transcriptomic neutron RBE of 1.30 (95% CI: 1.14-1.49) at 6 h and 1.21 (95% CI: 1.14-1.28) at 24 h, providing a valuable basis for biodosimetry in mixed-field exposure scenarios. Our findings advance the mechanistic understanding of neutron radiation responses and support the development of biodosimetric approaches for mixed-field exposure scenarios.

Background: ERAS protocols reduce hospital stay by 1.88 days and complications by 29% globally, but their one-size-fits-all paradigm, validated at sea level, may fail at high altitude where chronic hypoxia and population-specific genetic adaptations remodel baseline physiology. No study has quantified ERAS effect weight shifts at high altitude or proposed a theoretical model to explain the gap. Objectives: To evaluate three dimensions of plateau ERAS remodeling: (i) risk factor weight shift, (ii) traditional marker failure, (iii) genetic background modification, and propose the PAERS (Plateau Adaptation-ERAS Remodeling Syndrome) risk stratification model tailored to altitude. Methods: Retrospective cohort of 612 adults undergoing elective laparoscopic cholecystectomy (2018-2023) at Qinghai Red Cross Hospital (2260 m). Three analytical tiers: (1) multivariable regression comparing risk factor coefficients against plain-altitude benchmarks; (2) restricted cubic spline and interaction modeling for Hb, SpO2, and LOS; (3) inferential genetic modifier analysis using population-level EPAS1 carrier rates. Primary outcomes: LOS and complication rate. Results: Three-dimensional shift was observed: (1) Weight Remodeling: BMI replaced sex as primary risk factor (OR = 1.86, P < .001), surgeon variability amplified (F = 6.33 vs plain benchmark 2-4, an ~58% increase in F-statistic ratio, P < .001); (2) Marker Failure: Hb showed J-type relationship with LOS (Hb x SpO2 interaction beta = -0.0095, P = .009), with effect reversal across SpO2 strata (Plateau Hemoglobin Paradox); (3) Genetic Modification (population-level inference): ~70% EPAS1 carrier rate (range 57-85% across studies) suggests HIF-2alpha pathway is a baseline modifier that must be accounted for. Three falsifiable predictions were proposed. Conclusions: High-altitude ERAS faces three challenges: effect weight remodeling, biomarker failure, and genetic background calibration. The PAERS hypothesis proposes an integrated risk stratification model, shifting from one-size-fits-all to altitude-aware, patient-specific protocols.

Prolonged low-temperature exposure may extend the preservation window of mammalian cells but can also disrupt cellular homeostasis and ultimately compromise cell viability. This study investigated the time-dependent phenotypic and transcriptomic responses of primary canine dermal fibroblasts to sustained hypothermic stress. Passage-three fibroblasts were continuously maintained at 15 for up to 15 days, with samples collected on Days 0, 3, 6, 9, 12, and 15. Cellular morphology, metabolic activity and viability, and apoptosis were evaluated using bright-field microscopy, Cell Counting Kit-8 assays, and Annexin V-FITC/propidium iodide flow cytometry, respectively. RNA sequencing was performed to characterize dynamic transcriptional changes throughout the exposure period. Early low-temperature exposure was associated with relatively preserved cellular morphology and viability, suggesting a transient adaptive response. With increasing exposure duration, fibroblasts exhibited progressive morphological deterioration, reduced metabolic activity, loss of adhesion, and increased apoptosis. Time-series transcriptomic analysis further revealed temporally coordinated and stage-dependent gene-expression programs associated with metabolic regulation, cellular stress responses, structural homeostasis, and cell survival. Integration of phenotypic and transcriptomic data demonstrated that the response of primary canine dermal fibroblasts to 15 was dynamic rather than linear, progressing from early adaptation to cumulative dysfunction during prolonged exposure. These findings provide a framework for defining the low-temperature tolerance of primary canine dermal fibroblasts and may inform the optimization of protocols for their short- to medium-term preservation and transportation.

Background: Hemoglobin (Hb) elevation is the hallmark of high-altitude adaptation, yet its effect on surgical outcomes may depend on arterial oxygen saturation (SpO2)--previously uninvestigated. Objectives: To explore whether preoperative Hb effect on postoperative length of stay (LOS) after laparoscopic cholecystectomy (LC) reverses across SpO2 strata. Methods: Retrospective single-center cohort of 612 adults undergoing elective LC (2018-2023) at Qinghai Red Cross Hospital, Xining, China (2260 m). Exposure: preoperative Hb (82-233 g/L) and SpO2 (86%-99%), stratified as low (<93%), mid (93%-95%), high (>=96%). Primary analysis: multivariable linear regression with Hb x SpO2 interaction, adjusted for BMI, age, sex, season. Results: Among 612 patients (65.8% female; mean age 43.5 [11.9] years; mean Hb 151.4 [20.7] g/L; mean SpO2 94.6% [2.3%]), the Hb x SpO2 interaction was significant (beta = -0.0095; P = .009). Hb effect reversed: in SpO2 >=93%, each 1 g/L Hb prolonged LOS by 0.003 days (P = .079); in SpO2 <93%, each 1 g/L reduced LOS by 0.006 days. In mid-SpO2 stratum (n = 251), Hb >=180 g/L had longer LOS (1.88 vs 1.62 days; P = .001; d = 0.54). Five computational robustness analyses confirmed the interaction (leave-one-out: 100% P < .05 across 612 iterations). Conclusions: In this exploratory cohort, we observed an SpO2-dependent reversal of the Hb effect on postoperative LOS, designated the "Plateau Hemoglobin Paradox." Given single-center design and achieved power of 0.754, findings require replication. If replicated, this pattern may inform future perioperative risk stratification at high altitude.

A major barrier to scaling marine restoration and aquaculture is the lack of reliable tools to induce invertebrate larvae to settle and metamorphose when and where needed. Although microbial cues are known to induce metamorphosis in many invertebrates, existing methods rely on natural biofilms that are variable, difficult to standardize, and unsuitable for large-scale deployment. Here we introduce ReefTiles, a non-living bacterial coating that preserves inductive activity from metamorphosis-stimulating marine bacteria in a stable, reproducible format. Using both tubeworm and coral larvae, we show that dried and inactivated bacterial films retain full settlement-inducing capacity, matching or exceeding live biofilms while eliminating concerns associated with releasing viable microbes into the environment. Viability assays confirm inactivation, and the coating adheres reliably to common substrate materials. Because ReefTiles can be manufactured and stored at scale and tailored to different inductive strains, they provide a practical microbe-based biotechnology for enhancing larval settlement in reef restoration, sustainable aquaculture, and engineered marine infrastructure.

Previously, we have demonstrated that certain ferric salts common in Archean waters, such as iron trichloride and ferric ammonium citrate, can protect liposomes from destruction by short-wavelength UVC light. In this study, we investigate the propagation of 254 nm UV radiation through aqueous FeCl3 solutions and its interactions with liposomes. We then consider these findings in the context of early Earth UV environment, discuss their implications for our hypothesis of the Darwinian evolution of liposomes, and integrate them with our previous experimental results.

Environmental temperature strongly influences muscle contractile mechanics and locomotor performance in ectotherms, yet animals routinely develop across a range of temperatures while maintaining effective movement. We tested the hypothesis that developmental temperature induces compensatory changes in the intrinsic mechanical properties of the muscles that power the fast-start escape response in larval zebrafish (Danio rerio). Larvae were reared at 25{degrees}C, 28{degrees}C, or 32{degrees}C, and contractile properties of intact tail myotomal muscles were measured across experimental temperatures. Acute changes in experimental temperature strongly affected twitch kinetics, particularly relaxation rate (Q10 = 2.1), resulting in substantial changes in twitch duration. In contrast, rearing temperature produced adaptive changes that opposed these acute thermal effects. At a common experimental temperature, muscles from cold-reared larvae exhibited faster intrinsic relaxation and greater force production during shortening at a physiologically relevant velocity, whereas warm-reared larvae showed slower relaxation and reduced shortening force. As a result, twitch kinetics were largely normalized when measurements were made at each group's rearing temperature, reducing the apparent thermal sensitivity of relaxation rate (Q10 = 1.1). To identify molecular correlates of these functional adaptations, we performed label-free quantitative LCMS proteomic analysis. Cold rearing increased the abundance of Sarco/Endoplasmic Reticulum Calcium-ATPase (SERCA) proteins, driven primarily by elevated atp2a1 expression, while warm rearing reduced the abundance of the major parvalbumin isoforms pvalb1 and pvalb2. These changes implicate remodeling of intracellular calcium handling as a mechanism underlying thermal compensation of muscle function. Together, our results demonstrate that developmental temperature modifies the intrinsic mechanical properties of larval zebrafish muscle in ways that counteract the direct effects of environmental temperature, thereby preserving the timing and power-generating capacity required for fast-start escape performance.

Black carbon (BC), a combustion-derived component of fine particulate matter, has been linked to depressive symptoms, but controlled experimental evidence remains limited. We established a controlled BC inhalation model combined with chronic restraint stress (CRS) to determine whether inhaled BC alone induces depressive-like behavior and whether concurrent stress enhances behavioral and molecular vulnerability. Male C57BL/6J mice were assigned to Control, CRS, BC, or BC+CRS groups and exposed for 21 consecutive days, followed by behavioral testing and molecular analyses of plasma-depleted whole blood and stress-related brain regions. BC exposure alone induced depressive-like behavior, and the combined BC+CRS condition showed the most pronounced phenotype. These findings indicate that inhaled BC is sufficient to influence stress-relevant behavior and may heighten vulnerability under chronic stress. At the molecular level, BC shifted peripheral responses toward a stress- and inflammation-associated state with reduced plasticity-related signaling, whereas CRS preferentially engaged glucocorticoid-responsive regulation. Combined BC+CRS exposure further altered plasticity- and transcription-related regulatory programs in blood and stress-related brain regions, with prominent changes in the nucleus accumbens. These condition-dependent molecular patterns suggest that BC engages blood-brain stress-related pathways in a context- and region-specific manner. Together, these findings identify inhaled BC as a neurobehaviorally relevant environmental hazard.

Radiotherapy is common practice to treat cancer but produces significant side effects such as chronic pain. Cancer survivors report developing chronic pain due to their treatment even long after the cancer is cured. To understand the mechanisms underlying the radiotherapy-induced chronic pain, we assessed how ionising X-ray radiation exposure during 4 consecutive days of 5 Gy (total radiation dose of 20 Gy) affected dorsal root ganglia (DRG) sensory neurons (rodent F11 cell line). On the 5th day, we assessed known impacts of ionising radiation (senescence, oxidative stress, cellular metabolism, mitochondrial copy number, and mitochondrial respiration) followed by assessing expression of genes associated with populations of DRG neuronal fibres. We discovered that fractionated exposure to ionising radiation increased senescence, mitochondrial copy number, and modulated the NAD+/NADH pathway, but did not change the oxygen consumption rate nor induce oxidative stress 24 hours after the last irradiation exposure. Additionally, ionising radiation altered the expression of genes associated with mechanoreceptor fibres, known to have pro-nociceptive properties in the context of injury and chronic pain.

Snow algae are major biological drivers of snow darkening in polar and high-alpine environments. However, the direct contribution of algal pigmentation to snow reflectance has remained difficult to quantify because field observations cannot disentangle the effects of pigmentation from variation in biomass, species composition, and snow physical properties. Here, we characterized the optical effects of pigmentation using hyperspectral spectroradiometry to compare green, orange, and red cyst-like cells of a snow-derived Haematococcus isolate while controlling for developmental stage and cell abundance. Cysts became more red with increasing astaxanthin concentrations while chlorophyll-a concentrations remained relatively constant. Relative to green cysts, mean reflectance decreased by approximately 30% in orange cysts and 40% in red cysts. Integrated reflectance across the visible spectrum (350-800 nm) was negatively correlated with astaxanthin concentration. These results provide direct experimental evidence that algal pigmentation alone substantially reduces reflectance after controlling for cell abundance and developmental stage, and indicate that differences in snow physical properties may partly obscure this effect under natural field conditions. Our findings identify astaxanthin accumulation as an intrinsic driver of biological snow darkening and suggest that algal pigmentation, which may vary with species identity and physiological state, should be considered alongside biomass when predicting the radiative effects of snow algal blooms.

Sexual coral propagation is an emerging technique capable of producing large numbers of corals for coral transplantation and reef rehabilitation. In contrast to asexual coral propagation, sexual propagation increases genotypic diversity and can be used for selective breeding to enhance coral heat tolerance or other desirable traits. However, implementation at meaningful ecological scales is hindered by high mortality during early life stages, high costs associated with nursery rearing facilities, and labour-intensive outplanting methods. To overcome these issues, we developed the CoralAssist Plug (CAP), a ceramic device designed for the rapid and cost-effective outplanting of sexually propagated corals in large numbers that maximises post-outplant survivorship. CAPs combine three important functional features: 1) built-in microrefugia to protect juvenile corals from grazing, 2) a relatively small size, 3 by 1 cm, that is easy to handle and stack efficiently without compromising the survivorship of corals, and 3) a hole in the middle that facilitates handling and attachment. CAPs were settled with Acropora aff. digitifera and outplanted to a reef crest after 1 to 6 months of ex situ nursery rearing. A 3-person dive team was able to outplant ~120 CAPs in one 90-minute shallow dive (just over 2 minutes per CAP per person). With longer nursery durations of 6 months, it was possible to achieve 36 % yield (i.e., the proportion of devices with a surviving coral) 4-years post-outplant. With nursery durations shortened to 1 month, we were able to attain 24 % yield 3-years post-outplant. Microrefugia significantly enhanced post-outplant survivorship leading to an 11 % increase in yield 4 years post outplant compared to devices without microrefugia. Outplanted corals that had reached adult size, were self-attached and were reproductively mature after 4 years. Our results suggest that CAPs can play a meaningful role in reef rehabilitation by efficiently introducing sexually propagated corals into natural populations with clear applications to assisted evolution techniques, such as selective breeding.

The energetic cost of building human skeletal muscle has never been explicitly calculated or measured. We developed a quantitative bottom-up accounting model that integrates human skeletal-muscle composition with empirically informed estimates of tissue synthesis, physiological deposition, maintenance during accretion, and diet-induced thermogenesis. The calculation was expressed per kg of wet skeletal muscle and organized into five additive components: stored tissue energy, biochemical synthesis cost, physiological deposition cost, resting maintenance during accretion, and diet-induced thermogenesis. Stored tissue energy was approximately 5670 kJ/kg (1355 kcal/kg). Adding biochemical synthesis cost gave 6340 kJ/kg (1515 kcal/kg). Applying empirically derived deposition-efficiency parameters yielded a physiological deposition requirement of 9780 to 11690 kJ/kg (2338 to 2793 kcal/kg), centrally 10830 kJ/kg (2587 kcal/kg). Adding resting maintenance during accretion and diet-induced thermogenesis produced a final additional metabolizable energy intake of 13410 to 15520 kJ/kg (3204 to 3710 kcal/kg), centrally 14570 kJ/kg (3481 kcal/kg). This value provides a first quantitative reference estimate for the energetic cost of human skeletal-muscle accretion.

New maritime regulations restricting high-sulfur fuels have led to the transition to new low sulfur fuel oils (LFSOs). We do not know how LSFOs will behave in marine environments and how they will respond to available remediation strategies, presenting an environmental risk. The risk will be even higher in the remote high Arctic, especially along the Northwest Passage (NWP), for which an increase in shipping traffic is expected by the end of the century. In this study, we evaluated the long-term (one year) biodegradation potential of the native microbial community of NWP beach sediment using in situ mesocosm experiments with two different types of LSFOs: a marine gas oil (Marine diesel) and an ultra-low sulfur fuel oil (ULSFO). We observed that the lighter Marine diesel was biodegraded better (72.0%) than the heavier ULSFO (32.5%). We described composition of the microbial community of the mesocosms using 16S rRNA gene amplicon sequencing and observed a decrease in microbial diversity for the fuel-treated samples compared to the untreated controls. Despite the decrease in overall diversity, we observed significantly higher abundances of known hydrocarbon degrading microbes (e.g., Oleispira, Altererythrobacter, Gilvibacter, Pseudohongiella) in the fuel mesocosms. Our study showed the potential to implement biodegradation as a remediation strategy under the cold and oligotrophic environmental conditions present throughout the NWP. However, we also observed that microbes on their own cannot degrade the entirety of the removed fuel and other types of remediation will need to be considered to complement the natural biodegradation observed here.

Background: Autonomous ultraviolet-C (UV-C) disinfection systems are increasingly used to supplement manual environmental cleaning, yet evidence-based guidance defining pathogen-specific UV-C dose requirements across representative surfaces remains limited. Aim: To characterize operational UV-C dose requirements for clinically relevant pathogens across diverse high-touch and healthcare surfaces and determine how experimentally derived microbial inactivation can inform operational exposure parameters. Methods: SARS-CoV-2, adenovirus, Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Enterococcus faecalis, Candida auris, and Clostridioides difficile spores were exposed to defined UV-C doses on representative high-touch materials or stainless steel under standardized conditions, including a 10% fetal bovine serum organic soil challenge. Microbial inactivation was quantified by viable recovery. Dose-response analysis and operational modelling were used where supported by the experimental data. Findings: UV-C exposure significantly reduced viable recovery of all pathogens, with substantial differences in the exposure conditions associated with microbial inactivation. SARS-CoV-2 exhibited substantial inactivation at doses as low as 2.6 mJ/cm2, whereas the highest evaluated doses were 1,800 mJ/cm2 for C. difficile spores and 3600 mJ/cm2 for C. auris. For C. auris, multi-dose data estimated that approximately 1,410 mJ/cm2 was associated with a 2-log10 reference reduction, enabling distance-dependent exposure-time predictions. Conclusion: Experimentally quantified UV-C exposures produced substantial microbial inactivation across diverse pathogen classes and surfaces. Integrating delivered dose with microbial reduction provides a quantitative framework for translating laboratory efficacy into operational parameters for autonomous UV-C disinfection.

Efficient conversion of polymeric feedstocks for sustainable bioprocessing requires robust strategies for enzyme assembly and cell-surface attachment. In nature, cellulosomes achieve highly efficient lignocellulosic polysaccharide deconstruction through scaffoldin-mediated organization of carbohydrate-active enzymes via specific cohesin-dockerin interactions. These modular binding pairs are therefore attractive tools for synthetic biology and engineered whole-cell biocatalysis, yet their performance has been studied mainly in vitro or in yeast or Gram-positive bacteria. The factors governing their function on the microbial surfaces - particularly those of Gram-negative bacteria - remain incompletely understood. Here, we investigated the binding efficiency and interaction stability of two thermophilic cohesin-dockerin pairs from Acetivibrio thermocellus and Acetivibrio clariflavus displayed on the surface of the genome-streamlined strain Pseudomonas putida EM371 using an Ag43-based display system from Escherichia coli and a dockerin-tagged fluorescent reporter. We show that binding efficiency is strongly affected by the temperature at which the cohesin-dockerin complex is formed. We further demonstrate that the interaction stability of the A. clariflavus pair can be substantially improved by targeted amino acid substitutions in the dockerin domain guided by molecular dynamics simulations and free-energy calculations. These results identify key parameters controlling the performance of thermophilic cohesin-dockerin modules on living bacterial cell surfaces and establish a computation-guided strategy for engineering more stable cellulosome-derived assembly interfaces, advancing the development of modular whole-cell platforms for sustainable biotechnology applications. TOC graphics O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=107 SRC="FIGDIR/small/743725v1_ufig1.gif" ALT="Figure 1"> View larger version (65K): org.highwire.dtl.DTLVardef@18a97b6org.highwire.dtl.DTLVardef@1ee3ff4org.highwire.dtl.DTLVardef@a8dd60org.highwire.dtl.DTLVardef@5dd332_HPS_FORMAT_FIGEXP M_FIG C_FIG Cohesin-dockerin pairs provide strong and modular non-covalent interactions for synthetic biology and biotechnology applications. We establish an experimental and computational pipeline to improve their two key properties - binding efficiency and interaction stability - on the surface of Pseudomonas putida, enabling more robust cell-surface assembly systems.

Life on earth has always been exposed to the fluctuating Earth's magnetic field, but a magnetic sense affecting behavior has been debated for mammals. We here report that mice, kept under constant laboratory conditions, showed fluctuations in spontaneous behavioral activity with a periodicity of ~14 and ~28 days. This was confirmed in nine cohorts from four facilities on two continents, covering 3 to 41 months. Such oscillations were also maintained in brain Bmal1 knockout mice lacking circadian rhythms, suggesting independence of the circadian clock. The behavioral activity peaked around full and new Moon, and showed a strong alignment with the periodic geomagnetic fluctuations originating in the Earth's iono- and magnetosphere that are modulated by solar rotation and the orbital motion of the Moon. In the ultradian range, this alignment persisted in CRY1/2 knockout mice, suggesting that solar-lunar-driven geomagnetic fluctuations can modulate behavior rhythms independently of CRY1/2.