Biology subjects

Kang, C.

Publications and source records attributed to Kang, C..

At least 19 recordsLinked to original sources

bioRxiv2026

Spatial landscape of pretransplant liver disease and post-transplant immune outcomes in children

Defining molecular patterns underlying pediatric end-stage liver disease and its treatment with liver transplantation requires rich datasets spanning a multitude of diagnoses and transplant outcomes. Here, we describe the spatial molecular landscape of approximately five million liver cell profiles from 98 liver tissue samples. The samples span donor liver, used here as a reference tissue, and end-stage diseases including biliary atresia, progressive familial intrahepatic cholestasis, hepatoblastoma, acute liver failure, and gestational alloimmune liver disease. Post-transplant liver allograft biopsies include those without and with T-cell-mediated and antibody-mediated rejection, mixed pathology, and outcome groups from immunosuppression withdrawal studies. Samples were profiled using the CosMx Human Universal Cell Characterization RNA Panel (1K) and the CosMx Human 6K Discovery Panel (6K). Preliminary exploratory analyses include cellular composition and gene abundance and variability across clinical cohorts. A twelve-gene signature comprising the genes with the highest variance implicates acute-phase response genes (e.g., SAA1) and profibrotic genes (e.g., COL1A1) as a shared link across these otherwise distinct conditions. This injury-repair-remodeling gene network warrants further investigation through higher-resolution, zone-specific spatial mapping to help clarify disease pathogenesis.

genomics↗

bioRxiv2026

Deciphering epileptogenic and activity-dependent gene programs in the human brain

Neuronal activity is fundamental to brain function, yet chronically elevated activity underlies neurological disorders such as drug-resistant epilepsy (DRE). In animal models, activity induces defined transcriptional programs within activated neurons; however, the nature, cellular specificity, and pathological relevance of such programs in the human brain remain poorly understood. Here, we apply single-nucleus and spatial transcriptomics to epileptogenic, non-epileptogenic, and intraoperatively stimulated non-epileptogenic cortical tissue obtained from individuals with DRE. Across 26 cell types profiled, glutamatergic neurons projecting from cortical layers 2/3, 5, and 6 to intratelencephalic targets exhibit pronounced sensitivity to the epileptogenic microenvironment, inducing shared immediate-early genes alongside cell-type-specific programs linked to synaptic remodeling and cellular stress. Approximately one-third of transcripts enriched in the epileptogenic microenvironment were also induced by acute stimulation, suggesting that a fraction of epilepsy-associated gene expression reflects conserved responses to heightened activity rather than disease-specific programs. While transcripts induced by both epileptogenic and acute activity converged upon immediate-early genes and heat-shock proteins, only acute stimulation triggered a rapid, multicellular induction of transcripts involved in mitochondrial ATP synthesis. This divergence suggests that neurons within epileptogenic cortex may be unable to mount appropriate metabolic adaptations to sustained energetic demands. In parallel, both microglia and circulating CD14+ monocytes exhibit signs of immune activation in epilepsy, suggesting myeloid-driven inflammatory rewiring that extends beyond the brain. Together, these findings illuminate human activity-dependent gene programs and reveal signatures of neuronal vulnerability and inflammation in DRE.

neuroscience↗

bioRxiv2026

The nuclear receptor ROR-alpha is a critical myogenic regulator of the cardiomyocyte transcriptome, including the alpha-1A adrenergic receptor

AimsWe recently found that the nuclear receptor retinoic acid-related orphan nuclear receptor alpha (ROR) protects against angiotensin II-induced cardiac hypertrophy and promotes cardiomyocyte mitophagy. The underlying molecular basis for these salutary effects remains unclear. MethodsWe used RNA microarrays to profile the cardiac transcriptomes of "staggerer" (RORsg/sg) mice that carry a naturally occurring mutation in the ligand-binding domain of ROR, resulting in a global loss-of-function genetic model. We then used genetic and pharmacologic loss-and-gain of function studies in cultured cardiomyocytes to ascertain whether ROR regulates transcription of Adra1a, the gene that encodes the alpha-1A-adrenergic receptor (1A-AR). ResultsThe absence of functional ROR results in broad transcriptional changes in the heart providing a likely molecular basis for the RORsg/sg cardiac phenotype. In vivo and in vitro studies confirmed that ROR directly regulates Adra1a transcription. This effect is enhanced by hypoxia. ConclusionsCollectively these findings position ROR as a previously unrecognized central regulator of the cardiac myogenic transcriptome and the first recognized transcriptional regulator of Adra1a in cardiomyocytes. Future studies will probe the contribution of ROR-mediated transcriptional regulation of Adra1a to both the response to cardiomyocyte injury and maintenance of circadian biology.

physiology↗

bioRxiv2025

Temperature and Ultraviolet Radiation Drive Divergent Visible and Near-Infrared Reflectance Patterns in Butterflies

O_LIClimate change poses extreme risks to biodiversity, threatening the ecosystems upon which humanity depends. Understanding the traits that mediate how organisms respond to climatic gradients in space and time will enable better predictions of the taxa and ecological communities most at risk from warming. C_LIO_LIIn insects, colouration influences thermoregulation, but warming responses must be traded off against other selective pressures. We hypothesise that butterfly wing reflectance in visible and near-infrared (NIR) spectra respond differently to temperature and ultraviolet radiation over space and time. We combined existing reflectance data of 97 butterfly species in both NIR and visible wavelengths, with long-term abundance monitoring data of 120 butterfly communities sampled across 1650 m altitude gradients from May to August in two time periods (2004/5 and 2017). C_LIO_LIThe visible and NIR reflectances of butterfly communities showed a non-linear relationship with altitude, with the lowest reflectance (darkest butterflies) at the coolest, highest sites. In contrast, community visible reflectance decreased through the year as temperatures warmed over spring-summer, whereas community NIR reflectance remained constant, revealing divergent responses of reflectance types to seasonal changes. Temperature had opposing effects on visible and NIR reflectance of butterfly communities, where increasing temperature reduced community visible reflectance strongly while increasing community NIR reflectance slightly. C_LIO_LIConsidering the effects on reflectance of shared evolutionary history in a Bayesian hierarchical model for individual species, lighter-coloured (more reflective) species were associated with warmer temperatures - flying later in spring-summer or at lower altitudes. However, instead of decreasing in reflectance through the year and across temperature gradients, species instead became lighter, we expect as a result of a Simpsons paradox. C_LIO_LIThese results emphasise how visible and NIR reflectance wavelength bands mediate butterflies responses to environmental gradients in distinct ways, despite being highly correlated across species. We also show that incorporating phylogeny into trait-environment models is essential; relying on traits alone would lead to incorrect inferences and predictions of taxa most at risk from warming climates. C_LI

ecology↗

bioRxiv2025

The dominance of gene expression controlled by trans-eQTL hotspots contributes to phenotypic heterosis in maize

Heterosis, or hybrid vigor, is a key phenomenon in genetics research and agricultural production, and has been primarily attributed to non-additive genetic effects such as dominance -- a prevailing consensus shaped by decades of empirical research and theoretical debate. Although dominance may arguably arise from distal modifiers, their selective advantage is debated due to presumably small individual effects. To address this long-standing question, particularly how genetic dominance manifests at the transcriptomic level and contributes to phenotypic heterosis, we integrated transcriptomic and phenotypic data from a large population of maize hybrids and their inbred parents. We found that [~] 30% of the expressed seedling genes in a significant proportion of hybrids exhibited expression patterns deviating from the average of the two parents, indicative of non-additivity. Further analysis suggests that while hybrid gene expression per se is primarily regulated by cis-eQTLs, expression dominance (or non-additivity) is disproportionately controlled by trans-eQTLs. These trans-eQTLs cluster into hotspots that regulate the non-additivity of hundreds of target genes, mostly within co-expression networks, and are notably enriched for transcription factors (TFs). Focusing on one such hotspot, we functionally validated a classical maize gene ZmR1, a basic helix-loop-helix (bHLH) TF associated with multiple seedling trait heterosis, as a candidate regulator of expression dominance across hundreds of genes. Overexpression of ZmR1 enhances expression dominance of downstream genes and increases phenotypic heterosis in both seedling and adult traits. Further experiments confirmed its direct regulatory role in modulating genes involved in anthocyanin biosynthesis and lignin metabolism, driving transcriptome-level dominance. These results provide empirical support for the modifier hypothesis under an omnigenic model, suggesting that heterosis arises not from the modification of a single genes inheritance but through the coordinated regulation of hundreds of phenotype-associated genes, thereby helping to reconcile the long-standing debate over the genetic basis of dominance in heterosis.

genetics↗

bioRxiv2025

Discovery of a potent anti-Zika virus benzamide series targeting the viral protein NS4B

1.Zika virus (ZIKV), a member of the Flaviviridae family, causes significant public health concerns through congenital Zika syndrome and Guillain-Barre syndrome, yet no effective anti-ZIKV drugs or vaccines are available. To address this critical need, we conducted phenotypic, cytopathic effect-based, high-throughput screening followed by medicinal chemistry optimization and discovered novel benzamide anti-ZIKV leads. Current best compounds demonstrated superior potency (EC50 values 40-400 nM, CC50 > 50 {micro}M) compared to NITD-008, the most potent known anti-ZIKV agent. Time-of-addition assays, resistant virus selection studies, and biophysical binding experiments confirmed that NS4B interference constitutes the primary antiviral mechanism. Notably, resistance mutations mapped to the C-terminus of NS4B, distinct from other flavivirus NS4B inhibitors targeting dengue or yellow fever viruses, revealing novel insights into a critical function of the region. These findings establish NS4B as an Achilles heel for flaviviruses and support the development of pan-flavivirus therapeutics targeting this essential viral protein. 2. AUTHOR SUMMARYSince its pandemic spread in 2015-2016, Zika virus infection remains a significant public health threat worldwide. The virus can cause severe brain damage in developing babies and serious neurological complications like Guillain-Barre syndrome in adults. Despite these devastating consequences, we currently lack effective medicines or vaccines to prevent the virus from spreading through communities or from mothers to their unborn children. To address this critical gap, we conducted a large-scale screening of chemical compounds and discovered a promising new class of molecules that can effectively stop Zika virus from replication. Using medicinal chemistry techniques, we were able to make these compounds even more potent against the virus. In follow-up studies, we found that our compounds work by interfering with a specific viral protein called NS4B, which the virus needs to replicate its genome within the cell. Remarkably, other research teams studying related other flaviviruses (e.g., dengue and yellow fever virus) have independently discovered that this same protein is a vulnerable target. Our findings suggest that NS4B represents a universal weakness across the entire flavivirus family, making it an attractive target for developing broad-spectrum antiviral treatments.

microbiology↗

bioRxiv2025

Humanized Caffeine-Inducible Systems for Controlling Cellular Functions

Current cell therapies are limited by the lack of tools for controlling gene expression using humanized systems responsive to non-toxic stimuli. Starting from nanobodies that homodimerize in response to caffeine, we computationally designed inducible heterodimers and humanized the best-performing pairs. We used the resulting caffeine-inducible domains in engineered cytokine receptors for caffeine-inducible STAT3 signaling and in split transcription factors (caff-TFs) containing human-derived zinc-finger proteins. Heterodimerization of split transcription factors drastically enhanced their performance compared to homodimerization. We demonstrate that caff-TFs are compatible with lentiviral and retroviral delivery to Jurkat T-cells and enable inducible expression of therapeutic genes such as chimeric antigen receptors (CARs) in response to caffeine concentrations consistent with normal coffee consumption. By using the common, non-toxic molecule caffeine, and exclusively humanized protein components, these systems promise to be a safer alternative to existing systems and may be used in synthetic biology applications and for safer, more effective cell therapies.

synthetic biology↗

bioRxiv2025

FveTRM5 plays a critical role in regulating fruit shape in woodland strawberry

Cultivated strawberry is a globally important fruit crop with high economic value. Fruit shape contributes to fruit quality and diversity and is a target for breeding, but very few regulatory genes have been reported in strawberry. Here, we identified an ethyl methanesulfonate (EMS) round fruit (rf) mutant that produces round or flat fruits in woodland strawberry. The primary candidate point mutation is located in the second exon of FvH4_2g22810, causing a premature stop codon at residue 266. This gene encodes a protein with a high similarity to TON1 RECRUITING MOTIF 5 (TRM5) and has therefore been named FveTRM5. Transformation of FveTRM5pro:FveTRM5 into rf could rescue the round fruit phenotype, suggesting that FveTRM5 is responsible for rf. Overexpression of FveTRM5 produced elongated organs in both Arabidopsis and woodland strawberry, suggesting a conserved role in different species. FveTRM5 is ubiquitously expressed with higher levels in developing organs. Observation of cell shape showed that FveTRM5 promotes cell elongation and inhibits cell division in the medial-lateral direction in the receptacle. The FveTRM5 protein localized to microtubules. In conclusion, our results suggest that FveTRM5 plays an essential role in regulating strawberry fruit shape by influencing cell elongation and cell division, providing an excellent target gene for breeding new fruit shape cultivars.

plant biology↗

bioRxiv2024

Salmonella exploits host- and bacterial-derived β-alanine for replication inside host macrophages

Salmonella is a major foodborne pathogen that can effectively replicate inside host macrophages to establish life-threatening systemic infections. Salmonella must utilize diverse nutrients for growth in nutrient-poor macrophages, but which nutrients are required for intracellular Salmonella growth is largely unknown. Here, we found that either acquisition from the host or de novo synthesis of a nonprotein amino acid, {beta}-alanine, is critical for Salmonella replication inside macrophages. The concentration of {beta}-alanine is decreased in Salmonella-infected macrophages, while the addition of exogenous {beta}-alanine enhances Salmonella replication in macrophages, suggesting that Salmonella can uptake host-derived {beta}-alanine for intracellular growth. Moreover, the expression of panD, the rate-limiting gene required for {beta}-alanine synthesis in Salmonella, is upregulated when Salmonella enters macrophages. Mutation of panD impaired Salmonella replication in macrophages and colonization in the mouse liver and spleen, indicating that de novo synthesis of {beta}-alanine is essential for intracellular Salmonella growth and systemic infection. Additionally, we revealed that {beta}-alanine influences Salmonella intracellular replication and in vivo virulence partially by increasing expression of the zinc transporter genes znuABC, which in turn facilitates the uptake of the essential micronutrient zinc by Salmonella. Taken together, these findings highlight the important role of {beta}-alanine in the intracellular replication and virulence of Salmonella, and panD is a promising target for controlling systemic Salmonella infection.

microbiology↗

bioRxiv2024

Mechanical confinement induces ferroptosis through mitochondrial dysfunction

Cells exist in highly crowded environments where they are exposed to fluctuating mechanical forces arising from surrounding cells and the extracellular matrix microenvironment. In these settings, external forces are transmitted to intracellular organelles including the nucleus. While cells can survive confinement, extended duration of confinement or confinement in settings where cells are unable to escape, can result in cell death. How cells sense and respond to prolonged confinement to trigger cell death remains unclear. Here, we demonstrate that nuclear deformation generated by axial confinement triggers the programmed cell death pathway - ferroptosis. We show that axial confinement results in Drp1-dependent mitochondrial fragmentation and cPLA2 translocation to mitochondria, where Drp1 undergoes acute phase separation. Ensuing mitochondrial ROS accumulation and arachidonic acid production concertedly leads to lipid peroxidation evoking ferroptosis. Finally, of clinical relevance, we find that in human osteoarthritis tissue cPLA2 exhibits mitochondrial localization and high ROS levels. Together, our findings unveil a pivotal role for Drp1 and cPLA2 in linking mechanical confinement with mitochondrial dysfunction resulting in ferroptosis, which sheds new light on a mechanical mechanism of pathophysiology in osteoarthritis.

cell biology↗

bioRxiv2023

Functional implication of the homotrimeric multidomain vacuolar sorting receptor 1 (VSR1) from Arabidopsis thaliana

The vacuolar sorting receptors (VSRs) are specific to plants and are responsible for sorting and transporting particular proteins from the trans-Golgi network to the vacuole. This process is critically important for various cellular functions, including storing nutrients during seed development. Despite many years of intense studies on VSRs, a complete relation between function and structure has not yet been revealed. For the first time, the crystal structure of the full-length luminal part of glycosylated VSR1 from Arabidopsis thaliana (AtVSR1) has been determined. The structure provides insights into the tertiary and quaternary structures of VSR1, which are composed of an N-terminal protease-associated (PA) domain, a unique central region, and one epidermal growth factor (EGF) domain followed by two disordered EGF domains. The structure of VSR1 exhibits unique characteristics, the significance of which is yet to be fully understood.

plant biology↗

bioRxiv2023

The Discovery and Characterization of 1,4-Dihydroxy-2-naphthoic Acid Prenyltransferase Involved in the Biosynthesis of Anthraquinones in Rubia cordifolia

Anthraquinones constitute the largest group of natural quinones, which are used as safe natural dyes and have many pharmaceutical applications. In plants, anthraquinones are biosynthesized through two main routes: the polyketide pathway and the shikimate pathway. The shikimate pathway primarily forms alizarin-type anthraquinones, and the prenylation of 1,4-dihydroxy-2-naphthoic acid is the first pathway-specific step. However, the prenyltransferase responsible for this key step remains uncharacterized. In this study, the cell suspension culture of Rubia cordifolia, a plant rich in alizarin-type anthraquinones, was used in target prenyltransferase mining. The microsomal protein prepared from the cell suspension culture prenylated 1,4-dihydroxy-2-naphthoic acid to form 2-carboxyl-3-prenyl-1,4-naphthoquinone and 3-prenyl-1,4-naphthoquinone. Then a candidate gene belonging to UbiA superfamily, RcDT1, was discovered to account for the prenylation activity. Substrate specificity studies revealed that the recombinant RcDT1 recognized naphthoic acids primarily, followed by 4-hydroxyl benzoic acids. The prenylation activities of R. cordifolia microsomes and the recombinant RcDT1 were both strongly inhibited by 1,2- and 1,4-dihydroxynaphthalene. The plastid localization and root-specific expression further confirmed the participation of RcDT1 in anthraquinone biosynthesis. The phylogenetic analyses of RcDT1 and its rubiaceous homologs indicated that DHNA-prenylation activity evolved convergently in Rubiaceae via recruitment from the ubiquinone biosynthetic pathway. The discovery and evolutionary studies of RcDT1 provide useful guidance for identifying additional and evolutionarily varied prenyltransferases which enable entry into quinones derived from shikimate pathway. Moreover, these findings will have profound implications for understanding the biosynthetic process of the anthraquinone/naphthoquinone ring derived from shikimate pathway.

plant biology↗

bioRxiv2023

Mimicry in motion: A grasshopper species that looks like, and moves like, a sympatric butterfly

Flash displays describe the sudden revealing of a conspicuous signal by an otherwise cryptic animal as it is fleeing from predators. One hypothesis for flash displays is that they have evolved to mislead predators into adopting an inappropriate search strategy following pursuit. Thus, if predators believe that the fleeing prey item will also be conspicuous when settled, then they will tend to give up searching sooner if they fail to find it. Naturally, if this hypothesis is correct then one might expect that the value of the flash display would cease once predators learn the flashers true resting appearance. However, even if predators are aware that the resting appearance of the signaller could be cryptic, flash displays will still be selected for if the flasher resembles another species that maintains its conspicuous appearance throughout. Motivated by this insight, we quantified the degree of chromatic and behavioral resemblance between the Carolina grasshopper (Dissosteira carolina) and mourning cloak butterfly (Nymphalis antiopa), a sympatric species with which it is commonly confused. The close similarity in both morphology and flight behavior (in the field and lab) between these distantly related species strongly suggests that they are in a mimetic relationship. It is unclear why this mimicry has evolved. One explanation is that mimicry has arisen through selection to maintain the efficacy of the flash display through search disruption even after predator learning. Another possibility is that the grasshopper has evolved to resemble the butterfly because the latter is harder to catch (evasive mimicry). However, we argue that pursuit and search disruption are entirely complementary explanations for the mimetic resemblance because they interfere with predation at two different stages of the attack sequence.

animal behavior and cognition↗

bioRxiv2023

Amoeboid cells undergo durotaxis with soft end polarized NMIIA

Cell migration towards stiff substrates has been coined as durotaxis and implicated in development, wound healing and cancer, where complex interplays between immune and non-immune cells are present. Compared to the emerging mechanisms underlying the strongly adhesive mesenchymal durotaxis, little is known about whether immune cells - migrating in amoeboid mode - could follow mechanical cues. Here we develop an imaging-based confined migration device with stiffness gradient. By tracking live cell trajectory and analyzing the directionality of T cells and neutrophils, we observe that amoeboid cells can durotax. We further delineate the underlying mechanism to involve non-muscle myosin IIA (NMIIA) polarization towards the soft-matrix-side but may not require differential actin flow up- or down-stiffness gradient. Using the protista Dictyostelium, we demonstrate the evolutionary conservation of amoeboid durotaxis. Finally, these experimental phenomena are theoretically captured by an active gel model capable of mechanosensing. Collectively, these results may shed new lights on immune surveillance and recently identified confined migration of cancer cells, within the mechanically inhomogeneous tumor microenvironment or the inflamed fibrotic tissues.

cell biology↗

bioRxiv2023

A cinnamyl alcohol dehydrogenase (CAD) like enzyme leads to a branch in the shikonin biosynthetic pathway in Arnebia euchroma

Shikonin derivatives are natural naphthoquinone compounds and the main bioactive components produced by several boraginaceous plants, such as Lithospermum erythrorhizon and Arnebia euchroma. Phytochemical researches utilizing L. erythrorhizon and A. euchroma cultured cells both indicate the existence of a competing route branching out from the shikonin biosynthetic pathway toward benzo/hydroquinones. A previous study has shown that the branch point is a putative alcohol dehydrogenase converting (Z)-3-hydroxygeranylhydroquinone [(Z)-3-OH-GHQ] to an aldehyde intermediate (E)-3-oxo-GHQ. However, the enzyme involved in the branch reaction is not characterized at the molecular level yet. In this study, we clone a candidate gene belonging to the cinnamyl alcohol dehydrogenase (CAD) family, AeHGO, through coexpression analysis of transcriptome data sets of shikonin-proficient and shikonin-deficient cell lines of A. euchroma. In biochemical assays, purified AeHGO protein reversibly oxidizes (Z)-3-OH-GHQ to produce (E)-3-oxo-GHQ followed by reversibly reducing (E)-3-oxo-GHQ to (E)-3-OH-GHQ, resulting in an equilibrium mixture of the three compounds. Time course analysis and kinetic parameters show that the reaction with (Z)-3-OH-GHQ is about twice as efficient as with (E)-3-OH-GHQ, which leads to the predominance of (E)-3-OH-GHQ and (E)-3-oxo-GHQ in the equilibrium mixture. According to a previous report, (E)-3-oxo-GHQ can be converted to deoxyshikonofuran, a hydroquinone metabolite produced by boraginaceous plants. Considering there is a competition for accumulation between shikonin derivatives and benzo/hydroquinones in both L. erythrorhizon and A. euchroma cultured cells, AeHGO is supposed to play an important role in the metabolic regulation of shikonin biosynthetic pathway.

biochemistry↗

bioRxiv2022

The roles and evolution of the four LEAFY homologues in floral patterning and leaf development in woodland strawberry

The plant-specific transcription factor LEAFY (LFY), generally maintained as a single copy gene in most angiosperm species, plays critical roles in flower and leaf development. However, wild strawberry Fragaria vesca possesses four LFY homologues in the genome, their respective functions and evolution remain unknown. Through chemical mutagenesis screen, we identified two allelic mutations in one of the four LFY homologues, FveLFYa, in F. vesca, causing homeotic conversion of floral organs and reiterative outgrowth of ectopic florets. Both CRISPR-knockout and transgenic rescue confirmed the identity of FveLFYa. Ectopic expression in Arabidopsis lfy-5 mutant revealed that only FveLFYa and FveLFYb can rescue the flower defects and induce solitary flowers in leaf axils. Disruption of FveLFYc, the second abundantly expressed LFY homologue, caused no obvious morphology phenotypes in F. vesca. FveLFYb and FveLFYd are barely expressed. Expression of FveAP1, homologue of the well-known LFY target AtAP1, is not changed in the fvelfya flowers, possibly caused by an absence of any FveLFYa binding site in its promoter. Loss of Axillary Meristems encodes a GRAS transcription factor essential for stamen initiation. The ectopic florets are eliminated in fvelfya lam, suggesting that LAM is required for floret production. Moreover, approximately 30% of mature leaves have smaller or fewer leaflets in fvelfya. Among these homologues, only FveLFYa is syntenic to the homologues in other species. Overall, the detailed analyses of the four LFY homologues in woodland strawberry demonstrate that only FveLFYa plays crucial roles in floral patterning with rewired gene network.

plant biology↗

bioRxiv2022

Multisensory inputs control the regulation of time investment for mating by sexual experience in male Drosophila melanogaster

Males have finite resources to spend on reproduction. Thus, males rely on a time investment strategy to maximize their reproductive success. For example, male Drosophila melanogaster extends their mating duration when surrounded by conditions enriched with rivals. Here we report a novel form of behavioral plasticity whereby male fruit flies exhibit a shortened duration of mating when they are sexually experienced; we refer to this plasticity as shorter-mating-duration (SMD). SMD is a plastic behavior and requires sexually dimorphic taste neurons. We identified several neurons in the male foreleg and midleg that express specific sugar, pheromone and mechanosensory receptors. Using a cost-benefit model and behavioral experiments, we further show that SMD behavior exhibits adaptive behavioral plasticity in male flies. Thus, our study delineates the molecular and cellular basis of the sensory inputs required for SMD; this represents a plastic interval timing behavior that could serve as a model system to study how multisensory inputs converge to modify interval timing behavior for improved adaptation. ONE SENTENCE SUMMARYMale flies use information derived from their previous sexual experiences from multiple sensory inputs to optimize their investment in mating.

neuroscience↗

bioRxiv2021

A crystal structure of alphavirus nonstructural protein 4 (nsP4) reveals an intrinsically dynamic RNA-dependent RNA polymerase

Alphaviruses such as Ross River virus (RRV), chikungunya virus, Sindbis virus (SINV), and Venezuelan equine encephalitis virus are mosquito-borne pathogens that can cause arthritis or encephalitis diseases. Nonstructural protein 4 (nsP4) of alphaviruses possesses RNA-dependent RNA polymerase (RdRp) activity essential for viral RNA replication. No 3D structure has been available for nsP4 of any alphaviruses despite its importance for understanding alphaviral RNA replication and for the design of antiviral drugs. Here, we report crystal structures of the RdRp domain of nsP4 from both RRV and SINV determined at resolutions of 2.6 and 1.9 [A]. The structure of the alphavirus RdRp domain appears most closely related to RdRps from pestiviruses, noroviruses, and picornaviruses. Hydrogendeuterium exchange mass spectrometry (HDX-MS) and nuclear magnetic resonance (NMR) methods, showed that in solution, nsP4 is highly dynamic with an intrinsically disordered N-terminal domain. Both full-length nsP4 and the RdRp domain were capable to catalyze RNA polymerization. Structure-guided mutagenesis using a trans-replicase system identified nsP4 regions critical for viral RNA replication. Key PointsO_LICrystal structures of alphavirus nsP4 RNA polymerase domain from RRV and SINV. C_LIO_LInsP4 protein is highly dynamic with an intrinsically disordered N-terminal domain. C_LIO_LIOptimized RNA elongation activity assay to facilitate antiviral discovery. C_LI

molecular biology↗