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Journal of Biosciences

○ Springer Science and Business Media LLC

Preprints posted in the last 30 days, ranked by how well they match Journal of Biosciences's content profile, based on 15 papers previously published here. The average preprint has a 0.01% match score for this journal, so anything above that is already an above-average fit.

1
Positive and negative effects of CaMCA1 deletion on stress sensitivity and virulence

Wilkinson, D.

2026-09-23 microbiology 10.64898/2026.09.23.753419 medRxiv
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Metacaspases are cysteine proteases and are found in every group of organisms except animals. They are structural orthologs of caspases, which orchestrate apoptosis in animals. Caspases, metacaspases, paracaspases and orthocaspases are class C14 proteases with a similar active site (the hemoglobinase fold) and a catalytic cysteine residue. However, metacaspases cleave after arginine and lysine instead of aspartate and some researchers point out that a name ending with caspase is unsuitable. Also, most metacaspases are activated by calcium, they do not target the same proteins as caspases and they cut multiply instead of once. The Candida albicans metacaspase Mca1p mediates cell death in response to various stresses but also has pro-life functions. Many plant and protist metacaspases lack cell death roles and are involved in development, differentiation and immunity. This article highlights an interesting phenomenon, whereby the promotion of stress sensitivity and reduction of virulence, by Mca1p in C. albicans cells from exponential culture are abolished and reversed, respectively in cells from stationary-phase culture. This hints at the proteases's dual nature and at the conditions that might initiate a switch between pro-life and pro-death functions.

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Conservation value of secondary and plantation forests for fruit-feeding butterflies in northern Vietnam

Nguyen, T. M. T.; Pham, T. N.; Vu, V. L. V. L.; Le, B. T.; Molleman, F.

2026-10-09 ecology 10.64898/2026.10.07.757500 medRxiv
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1. Assessing the conservation value of secondary forests and reforestation is important for conservation planning. Butterflies are widely used as indicators, and fruit-feeding butterflies are often used in biodiversity assessments in tropical landscapes. 2. We examined fruit-feeding butterfly diversity, abundance, and community composition across a primary forest, a secondary forest, and a plantation forest in northern Vietnam. We sampled butterflies nearly monthly during one year using baited traps. 3. Primary and secondary forest supported higher species richness than plantation forest. Moreover, while secondary forest had mainly a subset of species found in primary forest, the plantation forest had a distinct butterfly fauna. 4. Butterfly abundance and community composition varied across months, without showing a clear seasonal pattern. 5. Our results suggest that secondary and plantation forests do not fully replace primary forests, but they contribute meaningfully to butterfly conservation in human-modified tropical landscapes.

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Novel protein networks in motile cilia from human epithelial cells revealed by cryo-ET and proteomics analysis of cilia from PCD patients

de Ceuninck van Capelle, C.; Cairoli, T.; Afanasyev, P.; Li, Y.; Markovic, E.; Jud, A.; Leitner, A.; Muller, L.; Ishikawa, T.

2026-09-29 cell biology 10.64898/2026.09.28.755144 medRxiv
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In our past study on human cilia from primary ciliary dyskinesia (PCD) patients using cryo-electron tomography and mass spectrometry, defects in the DNAH5 gene were proven to cause the loss of the entire outer dynein arm along with other proteins. This phenomenon was not observed in the unicellular green alga Chlamydomonas. In this study, we examined the loss of ciliary components caused by defects in various genes, based on proteomic and structural analyses of motile cilia from multiple PCD patients. The absence of single outer arm dynein genes causes a loss or significant decrease in other inner and outer arm dyneins. Interestingly, some patients with outer dynein defects show decreased intraflagellar transport (IFT) proteins, suggesting an influence of cargo components or assembly on transport. These phenomena were not observed in Chlamydomonas, suggesting a more complex mechanism of ciliogenesis in humans despite the high similarity in the final 3D architecture of the 9+2 axoneme. Defects in certain central pair proteins unexpectedly reduced components on the doublets as well. Our results demonstrate protein-protein interactions during stages of human motile ciliogenesis that are more complex than those in unicellular organisms.

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Genetic backgrounds and sex modulate indirect genetic effects of Epha4 in laboratory mice

Baud, A.; Matani, P.; Stedile, M.; Nacht, A. S.

2026-10-01 genetics 10.64898/2026.09.30.755759 medRxiv
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The phenotype of a focal individual can be affected not only by the individuals own genes (direct genetic effects, DGE) but also by genes of other individuals it interacts with (indirect genetic effects, IGE). Better understanding IGE can help better understand the impact and mechanisms of social effects. Here, we investigated, in laboratory mice, the modulation of IGE by genetic background of the focal individual (social epistasis) and by sex. We focused on IGE arising from Epha4, a gene that has been associated with the individuals own stress-related and social behaviours (i.e. DGE) and the stress-coping behaviour and wound healing of the other mice in the cage (i.e. IGE). Among four different genetic backgrounds for focal mice, significant IGE from Epha4 were detected in CBA females only. A formal model selection analysis was consistent with the modulation of IGE by the similarity of the genetic backgrounds of the focal mouse and its Epha4 cage mate, as well as by sex. Observations of fighting in cages of males with dissimilar genetic backgrounds suggested aggression might underpin these modulatory effects, which prompted to us to expand the conceptual framework describing the mechanisms of social epistasis. Thus, our results strengthen the emerging view that IGE are not fixed properties of social genotypes but can depend on the genetic and sex context of interacting individuals, revealing an underexplored layer of their genetic architecture.

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Gene-family-dependent thermodynamic effects of oncogenic mutations on nucleosome-DNA binding stability: a comparative molecular dynamics study across 22 cancer hotspots

Freudenberger, S.; Boczko, E.; Goel, S.; Maitra, R.

2026-09-30 bioinformatics 10.64898/2026.09.28.754892 medRxiv
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Oncogenic mutations are known to occur at non-random rates and specific hotspots, yet the structural and thermodynamic factors underlying these hotspots remain poorly understood. This study presents molecular dynamics simulations of 22 cancer hotspots across 10 oncogene families, simulated as histone-DNA complexes. Across 18 of 22 mutations, thermodynamic effects were predominantly localized to within 6 [A] of the DNA-histone interface (mean capture 104%), with van der Waals interactions driving the effect at the thermodynamic extremes, indicating that oncogenic mutations alter nucleosome binding through precise local contact changes rather than global structural rearrangements. Further, analysis revealed a gene-family correlated pattern in thermodynamic stability. RAS family mutations showed a consistent trend toward nucleosome stabilization (mean {Delta}{Delta}G = -4.82 kcal mol-1), while kinase domain mutations trended toward destabilization (mean {Delta}{Delta}G = +40.12 kcal mol-1), a difference reaching statistical significance in this exploratory analysis (Mann-Whitney U, p = 0.008). This interface-specific mechanism, combined with the gene-family-correlated thermodynamic pattern, provides a biophysical framework for understanding nucleosome-level contributions to cancer hotspot mutation biology.

6
Early Steps in Pathogen-induced TTR-amyloid-formation

Premathilaka, M. B.; Hansmann, U. H. E.

2026-09-24 molecular biology 10.64898/2026.09.21.753243 medRxiv
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Motivated by correlations between SARS-COV-2 infections and transthyretin (TTR) amyloidosis we use molecular dynamics simulations to study whether three protein fragments from the SARS-CoV-2 virus can initiate dissociation of the transthyretin (TTR) homotetramer as the first step on the pathway to TTR amyloidosis. We find that the peptides reduce the frequency of transient hydrogen bonds at the monomer-monomer interfaces, decreasing in this way the stability of the TTR tetramer.

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Syntaxin-1 and syntaxin binding protein 1-1 are required for planarian behavior and brain regeneration

Clay, K. B.; Roberts, P. A.; Lechtreck, K. F.; Roberts-Galbraith, R. H.

2026-10-12 neuroscience 10.64898/2026.10.05.756827 medRxiv
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Background: Nervous system regeneration requires creation of new neurons and their integration into new and existing networks. How new neurons find their targets and reconnect in the environment of regenerating tissue remains a major gap in knowledge. The planarian Schmidtea mediterranea is well suited to the study of neural regeneration due to the remarkable ability of planarians to regenerate their entire body, including the nervous system. However, we have not yet been able to explore synaptogenesis in regeneration using planarians due to a lack of tools to study synapses. Here we investigate potential players in planarian synapse, focusing on the conserved syntaxin protein family, which functions in neurotransmitter vesicle fusion at the synapse. Results: We found that reduction of either syntaxin-1 (stx1) or syntaxin-binding protein 1-1 (stxbp1-1) decreased locomotion and impeded brain regeneration, specifically in synapse-rich regions. Conclusions: Our observations support STX-1 and STXBP1-1 as bona fide synapse components, providing a starting point for studies neuronal connectivity during homeostatic remodeling and regeneration.

8
Evaluation of Human Norovirus Replication in Salivary Gland Cells

Harlow, J.; Briggs, S.; Pothier, E.; Pham, K.; Nasheri, N.

2026-10-01 microbiology 10.64898/2026.09.29.755260 medRxiv
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Human noroviruses (HuNoVs) are the most common cause of non-bacterial foodborne illnesses worldwide. HuNoVs are notoriously difficult to culture, and current cell culture systems, such as human intestinal enteroids have limitations in efficiency and scalability, which has limited their applications in food safety studies. Recently, it has been shown that transformed salivary gland cell lines (including NS-SV-TT-DC) allow for replication and passaging of norovirus GII.4. Herein, we examined whether we can independently observe viral replication in salivary gland cells and if other strains of human norovirus can replicate in these cells. For this purpose, we first evaluated the replication of several norovirus strains in NS-SV-TT-DC cells by either infecting them with vesicle-cloaked viruses or total viruses in stool filtrates. Low levels of viral replication was observed and vesicle isolation did not improve viral replication. Next, we screened for replication of 50 norovirus samples from 9 genotypes, and 14 isolates demonstrated over a two-fold viral replication. We observed that the initial viral load in the samples does not have a significant effect on replication efficiency. We were also able to passage several isolates. Subsequently, we examined whether interferon inhibitors such as Ruxolitinib, TPCA-1, and BX795 would improve viral replication and observed negligible effects. Finally we tested multiple supplements including MgCl2, bile salt, ceramide, and TAK-779. Most supplements had little or no effect on HuNoV replication in NS-SV-TT-DC cells. Bile salt and TAK-779 showed limited, genotype-specific benefits. Altogether these results indicate that salivary gland cells allow limited replication of certain HuNoV isolates.

9
How host self-regulation governs hyperparasitoid persistence in a caterpillar-parasitoid-trigonalid system

Rosales, Z. R.; Nava-Sedeno, J. M.

2026-09-29 ecology 10.64898/2026.09.28.755095 medRxiv
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Species at the highest trophic levels are generally the least resilient to perturbations, yet the factors that determine their persistence remain poorly understood. We ask how the intrinsic self-regulation of a basal host governs the persistence of the trophic levels above it. To address this question, we use a minimal discrete-time model of a host-parasitoid-hyperparasitoid system motivated by the biology of trigonalid wasps, obligate hyperparasitoids that complete development only when their caterpillar host is also attacked by a primary parasitoid. We compare two forms of host self-regulation in the absence of natural enemies: scramble (Ricker) fecundity, appropriate when the parasitoid is the host's principal enemy and which recovers the classical model of Beddington and Hammond as a special case; and contest (Beverton-Holt) fecundity, appropriate when the host is held in check by many additional enemies. Using numerical continuation, Lyapunov exponents, and direct computation of the model's trajectories, we find that the form of host regulation is decisive for persistence at the top trophic level. Under scramble host dynamics, coexistence is extremely fragile with respect to both parameter values and initial conditions. Under contest host dynamics, coexistence is robust across broad parameter ranges and loses stability only gradually, through a supercritical Neimark--Sacker bifurcation and a subsequent torus-doubling route to chaos. Therefore, in at least some trophic networks, the resilience of the highest levels can be determined at the base of the network.

10
Measurement-Induced Decision Loss: A feasible-set theory of microbiome intervention under observation loss

Aminian-Dehkordi, J.; Mofrad, M.

2026-10-07 systems biology 10.64898/2026.10.06.757205 medRxiv
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Microbiome measurements are commonly judged by how faithfully they reconstruct an underlying biological profile, using taxonomic similarity, prediction accuracy, or compositional distance. Yet faithfulness and usefulness are not the same: a distorted measurement may still support the correct intervention, while a small error can be decisive when it falls near the boundary between two treatment choices. We therefore evaluate measurement quality by whether information loss changes the decisions and outcomes that remain attainable. We treat the intervention-relevant state of the gut community as a hidden quantity seen only through an imperfect, information losing measurement, mapped by a decision rule to a graded intervention. Each decision rule is evaluated by net host benefit and ecological margin, generating a feasible set of attainable outcome pairs. We define the measurement-induced decision loss (MIDL) as the maximum net host benefit lost under imperfect measurement relative to perfect observation. For scalar affine information loss, increasing degradation is a Blackwell garbling; under post-processing closure, more informative measurement weakly expands the feasible set and cannot reduce optimal host benefit. In the binary-state model, MIDL increases linearly while an observation-dependent decision rule remains optimal and plateaus once the optimal policy becomes signal-independent. We extend the framework to finite states, state-specific loss, multi-segment stool aggregation, and ecological-margin constraints. The framework distinguishes measurement faithfulness from decision usefulness and provides a principled basis for comparing stool and richer measurements by the interventions and trade-offs they support.

11
Adjacent Z-DNA contributes to the formation of homologous DNA triplex

Zhong, M.; Liu, M.; An, R.; Gao, Y.; Liang, X.

2026-09-30 molecular biology 10.64898/2026.09.29.755329 medRxiv
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Whether the homologous parallel triplex (HP-triplex, formed by dsDNA and a homologous ssDNA) acts as an intermediate prior to DNA recombination remains controversy, owing to the intrinsic instability and lake of experimental data. Here, we report a HP-triplex that is stable at least at 35 oC under protein-free conditions. Two complementary circular ssDNAs were first hybridized at a 1:1 ratio to form an LR-chimera containing both Z-DNA and B-DNA. Then the circular homologous ssDNA (T-rich) was found to easily hybridize with this LR-chimera to form the HP-triplex (strand ratio of 2:1), involving both left- and right-handed triplex parts under the topological constraint. The third strand locates in the major groove and forms hydrogen bonds with both bases in each base pair of dsDNA without obvious strand exchange. Our data indicate that the third-strand ssDNA may first bind to the B-DNA region, followed by association with the Z-DNA region to assemble the full triplex structure. Structural simulations and analyses reveal that topological constraint imposed by the circular architecture raises the energy barrier for strand displacement, thereby stabilizing this triplex. In summary, the dynamic HP triplex can be stabilized via a Z B junction structure that mimics the in vivo one formed by negative supercoiling. These findings demonstrate that HP-triplex may act as an intermediate for DNA recombination, anti-gene strategy, and other interactions between dsDNA and homologous ssDNA or RNA.

12
MUTALISM BETWEEN Ambystoma maculatum AND Oophila amblystomatis IS DEPENDENT ON LIGHT INTENISTY DURING PHOTOSYNTHETIC GROWTH

PALUMBO, L.; Tattersall, G.; Clotheroe, W. E.; Bates, H.; Moldowan, P. D.; Zavafer, A.

2026-09-28 ecology 10.64898/2026.09.27.754580 medRxiv
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The most studied symbiosis between land vertebrates and algae, is the one between Ambystoma maculatum and Oophila amblystomatis, where the latter colonizes the amphibian''s eggs. Although clear benefit given by algal growth for the salamander embryo has been observed, mutualism is not widely accepted. Mutualistic hypotheses posit benefits from the host to the algae which include protection, N- and C-sources, but no experimental evidence has been obtained. In fact, recent studies suggest that the algae are stressed during this relationship and propose fermentation rather than photosynthesis as main driver for algal growth. In this work, we analyzed embryonic host developmental rate, algal and embryo growth and photosynthetic function of eggs housed at different light intensities. We provide evidence that photosynthetic growth is the main driver for Oophila and that higher algal growth yields faster developmental rate and embryo size. Also, we provide strong evidence that rates of photosynthetic electron transport (and the concomitant O2 evolution) must be higher than those of consumption by the embryo for this symbiosis to be mutualistic. Since photosynthetic rate is dependent on light, this work illustrates the importance of light intensity in this symbiotic relationship.

13
Highly inducible transcription is impaired in cells lacking Cyclin T1 (CycT1) of the positive transcription factor b (P-TEFb).

Kajitani, T.; Huang, F.; Nishiura, K.; Irwin, D.; Chein, A.; Fujinaga, K.

2026-09-28 molecular biology 10.64898/2026.09.26.754677 medRxiv
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In eukaryotic cells, the positive transcription elongation factor b (P-TEFb) plays a critical role in the transition of RNAPII from the paused state to actively transcribing mode. Although three different cyclin (Cyc) T (CycT1, T2a, and T2b) interact with CDK9 to form functional P-TEFb, a majority of P-TEFb complexes are comprised of the CycT1 and CDK9. To analyze the role of the CycT1 subunit of P-TEFb on cellular transcription, we established HEK293T cells lacking CycT1 proteins (CycT1-KO cells). While no apparent growth defects were observed with CYcT1-KO cells, the level of CDK9 was decreased and no compensatory over-expression of CycT2 was observed, suggesting that the reduced level of functional P-TEFb complexes is sufficient for the normal cell growth. Reporter gene assays indicate that NF-kappaB-dependent transcription induced by PMA was impaired in CycT1-KO cells although the function of NF-kappaB (P65) per se was not affected. On the other hand, AP1-dependent transactivation induced by PMA was unaffected in CycT1-KO cells. Moreover, transcription stimulated by JQ1, a strong P-TEFb inducer, was reduced in CycT1-KO cells. Data of biochemical analysis indicate that P-TEFb with CycT1 (P-TEFb (CDK9:CycT1)) was efficiently released from 7SKsnRNP by JQ1 while P-TEFb (CDK9:CycT2) was not affected by JQ1. Transcriptome analysis indicated that the lack of CycT1 had a minor effect on the steady-state transcription. However, expression of JQ1-dependent genes was severely reduced in CycT1-KO cells. Interestingly, referring to gene expression profiles of 33 different types of cancer revealed that 11 out of 13 top JQ1-dependent genes were also highly upregulated in Pancreatic Adenocarcinoma. From these results, we conclude that although many genes can be regulated by both P-TEFb (CDK9:CycT1) and P-TEFb (CDK9:CycT2), CycT1 plays a critical role in regulating highly inducible genes, which are also aberrantly regulated in a particular type of cancer.

14
Thermal stress disrupts microbial symbiosis and host activity in the model sponge Ianthella basta

Engelberts, J. P.; Rix, L.; Luter, H. M.; Glasl, B.; Jehmlich, N.; Kitzinger, K.; Cooke, I.; Legin, A.; Herbold, C. W.; Marini, M.; Dougan, K. A.; Robbins, S. J.; Wagner, M.; Webster, N. S.

2026-10-02 microbiology 10.64898/2026.10.01.756110 medRxiv
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Climate change is threatening coral reef ecosystems around the world, causing significant declines in reef organisms, including sponges. The health of sponges is intimately linked to their symbiosis with microorganisms, yet little is known about their integrated response to ocean warming. Here, we present a comprehensive view of the effect of elevated sea surface temperatures (SST) on the model sponge Ianthella basta. I. basta individuals were exposed to temperatures up to 32 {degrees}C, 2-3 {degrees}C above the mean annual maxima. Host gene expression profiles showed an initial response to heat stress after 2 days, and a decreased expression of genes involved in maintaining tissue integrity, pumping capacity, vitamin transport, and stable symbioses after 4 to 8 days. Congruently, heat stressed samples started to show tissue regression and a reduced abundance of the dominant symbionts after 4 days. A significant loss of the symbionts occurred after 8 days, together with a reduction in microbially driven nitrogen cycling and amino-acid transport and an introduction of opportunistic microbes, which could lead to nutrient imbalance and further destabilisation of the holobiont. Together, this work provides important insights into the avenues through which future SST can impact host-microbe interactions in coral reef sponges.

15
Type I and III interferons differentially encode inflammatory gene activation through threshold control of ISGF3 dynamics

Dubon Martinez, H.; Chettiyar, R.; McAuley, M.; Wilder, C. L.

2026-10-02 molecular biology 10.64898/2026.10.01.756040 medRxiv
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Type I and type III interferons (IFNs) activate the shared Janus kinase/signal transducer and activator of transcription (JAK-STAT) pathway but generate distinct inflammatory transcriptional responses in addition to their shared antiviral transcriptional induction. While some mechanisms including cytokine-receptor affinity and receptor abundance have been proposed for regulating type I vs type III IFN specificity, they account for differences in signal amplitude but do not fully explain IFN-specific changes in JAK-STAT activity over time (i.e. the signaling temporal dynamics) which has been shown to be predictive of inflammatory gene activation. Here, we investigated mechanisms that could explain how type I and III IFNs produce distinct temporal dynamics of the IFN-activated transcription factor IFN-stimulated gene factor 3 (ISGF3), leading to IFN-type specific activation of inflammatory genes in lung epithelial cells. We show that IFN-{beta}, a type I IFN, and IFN-{lambda}3, a type III IFN, induced comparable initial ISGF3 activation but subsequently generated distinct signaling trajectories, with IFN-{beta} undergoing potentiation and IFN-{lambda}3 limiting the duration of high ISGF3 activity, preventing robust inflammatory gene induction despite prolonged lower-level activity. Inflammatory gene induction was associated with the magnitude and duration of ISGF3 activity above an activation threshold during the intermediate phase of the signal response. The characteristic IFN-{lambda}3-induced ISGF3 signaling dynamics were maintained at saturating doses of IFN-{lambda}3 indicating the lack of signal activation above the threshold was independent of the dose. Additionally, differences in the abundance of the ISGF3 complex subunits STAT1, STAT2, and interferon regulatory factor 9 (IRF9), or in the induction of known negative regulators did not readily explain the response. Blocking protein synthesis caused rapid loss of IFN-{lambda}3-induced STAT phosphorylation and ISGF3 activity, supporting the presence of a pre-existing negative regulator limiting IFN-{lambda}3-mediated JAK-STAT pathway activation above the threshold required for activating inflammatory genes, while IFN-{beta} and IFN-{lambda}3 co-stimulation localized this regulation upstream of the shared ISGF3 complex. Increasing pathway competence through IFN-{beta} priming enhanced the IFN-{lambda}3-induced ISGF3 response above the inflammatory gene activation threshold leading to induction of inflammatory genes, albeit transiently. Together, these findings support a model in which the magnitude and duration of ISGF3 activity above an inflammatory gene activation threshold, rather than pathway activation alone, contribute to stimulus-specific transcriptional responses and suggest that a negative regulatory mechanism upstream of the ISGF3 complex constrains the temporal dynamics of IFN-{lambda}3 signaling.

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Epidemiological model selection unravels the molecular processes of antiviral resistance from experimental phytoplankton-virus dynamics

Rousseau, R.; Bugnot, C.; James, A.; Yau, S.; Piganeau, G.; Gourbiere, S.

2026-10-07 ecology 10.64898/2026.10.06.757099 medRxiv
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Phytoplankton-virus interactions are pivotal in understanding the intertwined dynamics of these key players of the global carbon cycle. Although antiviral resistance is the main hypothesis to solve the apparent paradox of their coexistence, identifying its molecular determinisms and mechanisms, as well as their dynamical consequences, remains challenging. By combining hypotheses about such determinisms and mechanisms, we designed 36 dynamical models and fitted them to experimental infection kinetics in a pioneering selection model approach. Through such a multiple hypotheses testing, we identified that resistance in the model species Ostreococcus tauri is most likely to be predominantly intracellular, to control lysis through budding, and to be acquired by phenotypic plasticity. We further showed that viral kinetics are strongly impacted by both the antiviral resistance's molecular determinants and virions' inactivation through attachment to lysis detritus, as the latter generates a key negative feedback loop during the 'bust' stage of the interaction dynamics.

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Genome-wide characterisation of the metallothionein gene family and their expression in response to copper in Pistia stratiotes (water lettuce).

Nyakauru, T.; O'Donovan, O.; O'Neill, D.

2026-09-24 genetics 10.64898/2026.09.19.752864 medRxiv
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Heavy metal contamination of aquatic environments poses persistent risks to ecosystems and human health. Aquatic macrophytes such as Pistia stratiotes are increasingly used for phytoremediation due to their capacity to accumulate contaminants without displaying symptoms of abiotic stress. However, the molecular mechanisms underlying their metal tolerance remain poorly understood. Metallothioneins (MTs) are cysteine-rich proteins involved in metal binding and detoxification in plants. In this study, genome-wide analysis was performed to identify and characterise candidate MT genes in P. stratiotes and to assess their transcriptional response to copper exposure. Six novel MT genes (PsMT2f, PsMT3a-d, and PsMT4) were identified and classified into MT2, MT3, and MT4 subfamilies based on conserved cysteine motifs and domain architecture. Quantitative real-time PCR showed differential and tissue-specific expression of MT genes in roots and leaves following exposure to copper for up to 4 h. These findings provide the first comprehensive characterisation of the MT gene family in P. stratiotes and demonstrate their potential role in copper tolerance, supporting the application of this species in the phytoremediation of metal-contaminated aquatic systems.

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Calcium-activated chloride channels, rather than the voltage-gated ones, regulate sperm capacitation

Ahmad, A.; Martinez Hernandez, J.; Corcini, C.; Akthatova, A.; Nowicka-Bauer, K.; Pinart, E.; Yeste, M.

2026-09-30 cell biology 10.64898/2026.09.29.755310 medRxiv
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Background: Ion channels regulate mammalian sperm function, yet chloride channels have received less attention than their cation counterparts. Herein, we investigated the presence, localization, and function of voltage-gated chloride channels (ClC-1, ClC-2, and ClC-K) and calcium-activated channels (ANO1 and ANO2) during sperm capacitation and the acrosome reaction. Results: Using the pig as an animal model, we localized these channels in different sperm regions: ClC-1 in the equatorial and post-acrosomal regions; ClC-2 in the connecting and principal pieces; ClC-K in the acrosome, connecting, and principal pieces; ANO1 in the principal piece; and ANO2 in the mid-piece and post-acrosomal sheath region. Following this, we addressed the roles of these channels in sperm capacitation and acrosome reaction by blocking them with different inhibitors: 9AC, specific for ClCs; BBR, specific for CaCCs; and NPPB, a broad-spectrum blocker that inhibits ClCs, CaCCs, and other chloride channels. Blocking CaCCs with BBR led to a significant reduction in sperm motility and mitochondrial membrane potential, with effects similar to those of the non-selective inhibitor NPPB or to a combination of BBR and NPPB. Moreover, although none of the three inhibitors affected intracellular calcium levels or acrosomal integrity, a significant reduction in protein tyrosine phosphorylation was observed in sperm treated with the combination of NPPB and BBR. Finally, membrane lipid disorder was increased when ClCs were blocked with 9AC and when sperm were incubated with a combination of BBR and NPPB. Conclusions: Our results suggest that CaCCs play a major role in sperm capacitation compared to ClCs. Further research to address the regulatory mechanisms involved and the potential relationship with other ion channels is warranted.

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Experimental and mathematical models reveal that AMPK modulates circadian clock gene expression and period through NAD+-dependent regulation of Bmal1

Vandenberghe, A.; Delpierre, P.; Torero-Ibad, R.; Leclerc, P.; Treizebre, A.; Berthier, A.; Heliot, L.; Duez, H.; Staels, B.; Lefebvre, P.; Furlan, A.; Lefranc, M.

2026-09-30 cell biology 10.64898/2026.09.29.755034 medRxiv
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The circadian clock allows living systems to anticipate environmental daily variations by scheduling cellular mechanisms according to the time of the day. The reciprocal interplay between metabolism and circadian clock is essential for energy homeostasis, and the disruption of metabolic clock inputs contributes to dysfunction of clocks in peripheral tissues. However, the molecular mechanisms through which the feeding/fasting cycle entrains peripheral clocks remain incompletely understood. Here, we investigate experimentally and theoretically the role of AMP-dependent kinase (AMPK), a key fasting sensor, in metabolic regulation of the circadian clock. Using a luciferase reporter driven by the Bmal1 promoter to monitor molecular clock activity in human U2OS cells, and thanks to a signal processing method based on the Hilbert transform to retrieve the instantaneous phase and period of circadian signals, we show that pharmacological activation of AMPK by AICAR significantly elevates Bmal1 promoter activity and markedly lengthens the clock period in a dose-dependent manner. Conversely, the clock period is shortened by the pharmacological inhibition by SR18292 of Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1-alpha). Importantly, the action of AICAR is abolished by FK866, a nicotinamide phosphoribosyltransferase (NAMPT) inhibitor, demonstrating that AMPK-dependent modulation of Bmal1 promoter activity requires NAD+ availability. These experimental results are recapitulated by numerical simulations of our previously published mathematical model, where PGC-1-alpha plays a key role in mediating AMPK activity to the clock. Moreover, the comparison of experimentally measured and theoretically predicted phase response curves, following AMPK activation at different circadian phases, provides an additional validation of the model. By integrating biological experiments with mathematical modeling, our results identify a key mechanism through which metabolic factors can entrain and regulate the circadian clock via NAD+-dependent AMPK-mediated regulation of Bmal1 promoter activity.

20
Tumor-associated mammary fibroblast matrices contain O-glycosylated oncofetal fibronectin

Longstreth, J. H.; Patel, D.; Bashiri, G.; Wang, K.

2026-09-30 bioengineering 10.64898/2026.09.29.755525 medRxiv
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Oncofetal fibronectin (oFN) is a known biomarker of cancer progression and is involved in events such as epithelial mesenchymal transition and multidrug resistance. It is also understood that fibronectin (FN) and its splice variants are differentially arranged by cancer associated fibroblasts (CAFs) to support cancer cell proliferation and migration. Contrastingly, little is understood about the mechanobiology of oFN, a post-translationally modified FN isoform defined by O-glycosylation of a specific threonine residue. To investigate the architectural features of the oFN matrix, CAFs were simulated by culturing human mammary fibroblasts (HMFs) on stiff polyacrylamide gels (20 kPa) in media collected from HCC-1937 (primary site breast adenocarcinoma) and MDA-MB-231 (metastatic breast adenocarcinoma) cells. As a control, HMFs were also cultured on softer gels representing healthy adipose tissue (2 kPa) in media not exposed to cancer cells. After immunocytochemical analysis, tumor conditioned HMFs displayed an expected CAF-like phenotype that was most prominent with MDA-MB-231 conditioned media. Matrices produced by tumor-conditioned HMFs contained more oFN with structural features mostly following that of the overall dense, aligned FN matrix. Cancer cells reseeded on their corresponding decellularized tumor-associated matrices had greater F-actin/oFN colocalization than control matrix. The lack of distinct oFN topographical cues may indicate that oFN O-glycosylation is more directly involved in biochemical signaling than mechanosignaling through matrix architecture. Together, this study established a platform for investigating stromal oFN which revealed that tumor-conditioned media sourced from cancer cells with different metastatic potential influences HMF activation, leading to distinct total FN and thus oFN matrix microarchitecture features.