The microbiome dynamics and interaction of endosymbiotic Symbiodiniaceae and fungi are associated with thermal bleaching susceptibility of coral holobionts.

The thermal bleaching percentage of coral holobionts shows interspecific differences under heat-stress conditions, which are closely related to the coral-associated microbiome. However, the ecological effects of community dynamics and interactions between Symbiodiniaceae and fungi on coral thermal bleaching susceptibility remain unclear. In this study, we analyzed the diversity, community structure, functions, and potential interaction of Symbiodiniaceae and fungi among 18 coral species from a high thermal bleaching risk atoll using next-generation sequencing. The results showed that heat-tolerant C3u sub-clade and Durusdinium dominated the Symbiodiniaceae community of corals and that there were no core amplicon sequence variants in the coral-associated fungal community. Fungal richness and the abundance of confirmed functional animal-plant pathogens were significantly positively correlated with the coral thermal bleaching percentage. Fungal indicators, including Didymellaceae, Chaetomiaceae, Schizophyllum, and Colletotrichum, were identified in corals. Each coral species had a complex Symbiodiniaceae-fungi interaction network (SFIN), which was driven by the dominant Symbiodiniaceae sub-clades. The SFINs of coral holobionts with low thermal bleaching susceptibility exhibited low complexity and high betweenness centrality. These results indicate that the extra heat tolerance of coral in Huangyan Island may be linked to the high abundance of heat-tolerant Symbiodiniaceae. Fungal communities have high interspecific flexibility, and the increase of fungal diversity and pathogen abundance was correlated with higher thermal bleaching susceptibility of corals. Moreover, fungal indicators were associated with the degrees of coral thermal bleaching susceptibility, including both high and intermediate levels. The topological properties of SFINs suggest that heat-tolerant coral have limited fungal parasitism and strong microbial network resilience.IMPORTANCEGlobal warming and enhanced marine heatwaves have led to a rapid decline in coral reef ecosystems worldwide. Several studies have focused on the impact of coral-associated microbiomes on thermal bleaching susceptibility in corals; however, the ecological functions and interactions between Symbiodiniaceae and fungi remain unclear. We investigated the microbiome dynamics and potential interactions of Symbiodiniaceae and fungi among 18 coral species in Huangyan Island. Our study found that the Symbiodiniaceae community of corals was mainly composed of heat-tolerant C3u sub-clade and Durusdinium. The increase in fungal diversity and pathogen abundance has close associations with higher coral thermal bleaching susceptibility. We first constructed an interaction network between Symbiodiniaceae and fungi in corals, which indicated that restricting fungal parasitism and strong interaction network resilience would promote heat acclimatization of corals. Accordingly, this study provides insights into the role of microorganisms and their interaction as drivers of interspecific differences in coral thermal bleaching.

Hnrnpk protects against osteoarthritis through targeting WWC1 mRNA and inhibiting Hippo signaling pathway.

Osteoarthritis (OA) is an age-related or post-traumatic degenerative whole joint disease characterized by the rupture of articular cartilage homeostasis, the regulatory mechanisms of which remain elusive. This study identifies the essential role of heterogeneous nuclear ribonucleoprotein K (hnRNPK) in maintaining articular cartilage homeostasis. Hnrnpk expression is markedly downregulated in human and mice OA cartilage. The deletion of Hnrnpk effectively accelerates the development of post-traumatic and age-dependent OA in mice. Mechanistically, the KH1 and KH2 domain of Hnrnpk bind and degrade the mRNA of WWC1. Hnrnpk deletion increases WWC1 expression, which in turn leads to the activation of Hippo signaling and ultimately aggravates OA. In particular, intra-articular injection of LPA and adeno-associated virus serotype 5 expressing WWC1 RNA interference ameliorates cartilage degeneration induced by Hnrnpk deletion, and intra-articular injection of adeno-associated virus serotype 5 expressing Hnrnpk protects against OA. Collectively, this study reveals the critical roles of Hnrnpk in inhibiting OA development through WWC1-dependent downregulation of Hippo signaling in chondrocytes and defines a potential target for the prevention and treatment of OA.

High organic aerosol in the low layer over a rural site in the North China Plain (NCP): Observations based on large tethered balloon.

High mass concentration of organic aerosol (OA) and its fraction in PM2.5 (particle matter with radius <2.5 µm) were observed in the low layer over a rural site of the North China Plain (NCP) in winter 2018. The mass fraction of OA in PM2.5 was 65.5 % at ground level (5 m above ground), and decreased to 37.1 % in layer of 200-1000 m. In addition, there was a sharp decrease of OA at around the top of planetary boundary layer (PBL), which was distinctly different from the vertical distributions of secondary inorganic aerosols (SIA, e.g., nitrate (NO3-), ammonium (NH4+), and sulfate (SO42-)). The altitude with sharp decrease of OA was very low in the morning and evening, e.g., the sharp decrease of OA occurred at a height <50 m at nighttime on Dec. 19, while was elevated in the noon with the PBL development. Furthermore, OA at ground level exhibited a distinct diurnal variation with a night-to-day ratio of 2.3, which was much larger than those of SIA and inactive CO. All the above results indicated the extremely high OA concentration at the rural site was mainly attributed to direct emission from local sources, such as the combustion of coal and biomass for heating. The extremely high OA could be expected in vest rural areas of the NCP in winter because the farmer activities are very similar to the investigated rural site, underscoring the urgency to mitigate OA emission in rural area for improving the local as well as the regional air quality.

Evolutionary radiation and microbial community dynamics shape the thermal tolerance of Fungiidae in the southern South China Sea.

Fungiidae have shown increased thermal adaptability in coral reef ecosystems under global warming. This study analyzes the evolutionary divergence and microbial communities of Fungiidae in the Sanjiao Reef of the southern South China Sea and explores the impact of coral evolution radiation and microbial dynamics on the heat tolerance of Fungiidae. The results found that Cycloseris was an ancient branch of Fungiidae, dating back approximately 147.8953 Mya, and Fungiidae differentiated into two ancestral clades (clades I and II) before 107.0312 Ma. Fungiidae exhibited specific symbioses with the Cladocopium C27 sub-clade. Notably, the Cladocopium C1 sub-clade has a high relative abundance in clade I, whereas the heat-tolerant Cladocopium C40 and C3u sub-clades subdominante in clade II. Regarding bacterial communities, Cycloseris costulata, the earliest divergent species, had higher bacterial ß-diversity, while the latest divergent species, Lithophyllon scabra, displayed lower bacterial α-diversity and higher community stability. Beneficial bacteria dominante Fungiidae's bacterial community (54%). The co-occurrence network revealed that microbial networks in clade II exhibited lower complexity and greater resilience than those in clade I. Our study highlights that host evolutionary radiation and microbial communities shaped Fungiidae's thermal tolerance. The variability in subdominant Symbiodiniaceae populations may contribute to interspecific differences in thermal tolerance along the evolutionary branches of Fungiidae. The presence of abundant beneficial bacteria may further enhance the thermal ability of the Fungiidae. Furthermore, the later divergent species of Fungiidae have stronger heat tolerance, possibly driven by the increased regulation ability of the host on the bacterial community, greater microbial community stability, and interaction network resistance.IMPORTANCECoral reefs are facing significant threats due to global warming. The heat tolerance of coral holobionts depends on both the coral host and its microbiome. However, the association between coral evolutionary radiation and interspecific differences in microbial communities remains unclear. In this study, we investigated the role of evolutionary radiation and microbial community dynamics in shaping the thermal acclimation potential of Fungiidae in the Sanjiao Reef of the southern South China Sea. The study's results suggest that evolutionary radiation enhances the thermal tolerance of Fungiidae. Fungiidae species that have diverged more recently have exhibited a higher presence of heat-tolerant Symbiodiniaceae taxa, more stable bacterial communities, and a robust and resilient microbial interaction network, improving the thermal adaptability of Fungiidae. In summary, this study provides new insights into the thermal adaptation patterns of corals under global warming conditions.

Metabolic and immune costs balance during natural acclimation of corals in fluctuating environments.

Epigenetic modifications based on DNA methylation can rapidly improve the potential of corals to adapt to environmental pressures by increasing their phenotypic plasticity, a factor important for scleractinian corals to adapt to future global warming. However, the extent to which corals develop similar adaptive mechanisms and their specific adaptation processes remain unclear. Here, to reveal the regulatory mechanism by which DNA methylation improves thermal tolerance in Pocillopora damicornis under fluctuating environments, we analyzed genome-wide DNA methylation signatures in P. damicornis and compared the differences in the methylation and transcriptional responses of P. damicornis from fluctuating and stable environments using whole-genome bisulfite sequencing and nanopore-based RNA sequencingtranscriptome sequencing. We discovered low methylation levels in P. damicornis (average methylation 4.14%), with CpG accounting for 74.88%, CHH for 13.27%, and CHG for 11.85% of this methylation. However, methylation levels did not change between coral samples from the fluctuating and stable environments. The varied methylation levels in different regions of the gene revealed that the overall methylation level of the gene body was relatively high and showed a bimodal methylation pattern. Methylation occurs primarily in exons rather than introns within the gene body In P. damicornis, there was only a weak correlation between methylation and transcriptional changes at the individual gene level, and the methylation and gene expression levels generally exhibited a bell-shaped relationship, which we speculate may be due to the specificity of cnidarian species. Correlation analysis between methylation levels and the transcriptome revealed that the highest proportion of the top 20 enriched KEGG pathways was related to immunity. Additionally, P. damicornis collected from a high-temperature pool had a lower metabolic rate than those collected from a low-temperature pool. We hypothesize that the dynamic balance of energy-expenditure costs between immunity and metabolism is an important strategy for increasing P. damicornis tolerance. The fluctuating environment of high-temperature pools may increase the heat tolerance in corals by increasing their immunity and thus lowering their metabolism.

Rapid Induction of Long-Lasting Systemic and Mucosal Immunity via Thermostable Microneedle-Mediated Chitosan Oligosaccharide-Encapsulated DNA Nanoparticles.

Most existing vaccines, delivered by intramuscular injection (IM), are typically associated with stringent storage requirements under cold-chain distribution and professional administration by medical personnel and often result in the induction of weak mucosal immunity. In this context, we reported a microneedle (MN) patch to deliver chitosan oligosaccharide (COS)-encapsulated DNA vaccines (DNA@COS) encoding spike and nucleocapsid proteins of SARS-CoV-2 as a vaccination technology. Compared with IM immunization, intradermal administration via the MN-mediated DNA vaccine effectively induces a comparable level of neutralizing antibody against SARS-CoV-2 variants. Surprisingly, we found that MN-mediated intradermal immunization elicited superior systemic and mucosal T cell immunity with enhanced magnitude, polyfunctionality, and persistence. Importantly, the DNA@COS nanoparticle vaccine loaded in an MN patch can be stored at room temperature for at least 1 month without a significant decrease of its immunogenicity. Mechanically, our strategy enhanced dendritic cell maturation and antiviral immunity by activating the cGAS-STING-mediated IFN signaling pathway. In conclusion, this work provides valuable insights for the rapid development of an easy-to-administer and thermostable technology for mucosal vaccines.

The diversity, community dynamics, and interactions of the microbiome in the world's deepest blue hole: insights into extreme environmental response patterns and tolerance of marine microorganisms.

IMPORTANCE: This study comprehensively examined the community dynamics, functional profiles, and interactions of the microbiome in the world's deepest blue hole. The findings revealed a positive correlation between the α-diversities of Symbiodiniaceae and archaea, indicating the potential reliance of Symbiodiniaceae on archaea in an extreme environment resulting from a partial niche overlap. The negative association between the α-diversity and ß-diversity of the bacterial community suggested that the change rule of the bacterial community was consistent with the Anna Karenina effects. The core microbiome comprised nine microbial taxa, highlighting their remarkable tolerance and adaptability to sharp environmental gradient variations. Bacteria and archaea played significant roles in carbon, nitrogen, and sulfur cycles, while fungi contributed to carbon metabolism. This study advanced our understanding of the community dynamics, response patterns, and resilience of microorganisms populating the world's deepest blue hole, thereby facilitating further ecological and evolutional exploration of microbiomes in diverse extreme environments.

Analysis of severe ozone-related human health and weather influence over China in 2019 based on a high-resolution dataset.

Ozone pollution in 2019 in China is particularly severe posing a tremendous threat to the health of Chinese inhabitants. In this study, we constructed a more reliable and accurate 1-km gridded dataset for 2019 with as many sites as possible using the inverse distance weight interpolation method to analyze spatiotemporal ozone pollution characteristics and health burden attributed to ozone exposure from the perspective of different diseases and weather influence. The accuracy of this new dataset is higher than other public datasets, with the coefficient of determination of 0.84 and root-mean-square error of 8.77 ppb through the validation of 300 external sites which were never used for establishing retrieval methods by the datasets mentioned-above. The averaged MDA8 (the daily maximum 8 h average) ozone concentrations over China was 43.5 ppb, and during April-July, 83.9% of total grids occurred peak-month ozone concentrations. Overall, the highest averaged exceedance days (60 days) and population-weighted ozone concentrations (55.0 ppb) both concentrated in central-eastern China including 9 provinces (only 11.4% of the national territory); meanwhile, all-cause premature deaths attributable to ozone exposure reached up to 142,000 (54.9% of national total deaths) with higher deaths for cardiovascular and respiratory, and the provincial per capita premature mortality was 0.27~0.44‰. The six most polluted weather types in the central-eastern China are in order as follows: westerly (SW and W), cyclonic, northerly, and southerly (NW, N, and S) types, which accounts for approximately 73.2% of health burden attributed to daily ozone exposure and poses the greatest public health risk with mean daily premature deaths ranging from 466 to 610. Our findings could provide an effective support for regional ozone pollution control and public health management in China.

Adaptation strategies of relatively high-latitude marginal reef corals in response to severe temperature fluctuations.

The large seasonal temperature fluctuations caused by global warming and frequent marine heatwaves pose new challenges to survival of relatively high-latitude marginal reef corals. However, the adaptation strategies of high-latitude marginal corals are not fully understood. We employed integrated approach to investigate the response mechanism of hosts, Symbiodiniaceae, and symbiotic bacteria of marginal reef corals Acropora pruinosa and Pavona decussate in response to large seasonal temperature fluctuations. The coral holobiont maintained a high level of immunity to adapt to seasonal pressure by increasing Symbiodiniaceae energy supply. The symbiotic Symbiodiniaceae of two coral was dominated by C1 subgroup, and was stable across seasons. The α-diversity of symbiotic bacteria P. decussata and A. pruinosa in summer was higher than that in winter. The symbiotic bacterial community of two coral reorganized during different seasons. Scleractinian corals improve adaptability to seasonal stress by increasing energy supply to maintain high levels of immunity, increasing symbiotic bacterial α-diversity, and changing dominant bacteria. This study demonstrates the adaptation strategies of marginal reef corals to seasonal temperature fluctuations and provides novel insights into the study of the adaptation of corals and relatively high-latitude coral refuges in the context of global warming and intensified marine heatwaves.

Hnrnpk is essential for embryonic limb bud development as a transcription activator and a collaborator of insulator protein Ctcf.

Proper development of the limb bud relies on the concordance of various signals, but its molecular mechanisms have not yet been fully illustrated. Here we report that heterogeneous nuclear ribonucleoprotein K (hnRNPK) is essential for limb bud development. Its ablation in the limb bud results in limbless forelimbs and severe deformities of the hindlimbs. In terms of mechanism, hnRNPK functions as a transcription activator for the vital genes involved in the three regulatory axes of limb bud development. Simultaneously, for the first time we elucidate that hnRNPK binds to and coordinates with the insulator protein CCCTC binding factor (CTCF) to maintain a three-dimensional chromatin architecture. Ablation of hnRNPK weakens the binding strength of CTCF to topologically associating domain (TAD) boundaries, then leading to the loose TADs, and decreased interactions between promoters and enhancers, and further decreased transcription of developmental genes. Our study establishes a fundamental and novel role of hnRNPK in regulating limb bud development.

Spatiotemporal Characterization of Human Early Intervertebral Disc Formation at Single-Cell Resolution.

The intervertebral disc (IVD) acts as a fibrocartilaginous joint to anchor adjacent vertebrae. Although several studies have demonstrated the cellular heterogeneity of adult mature IVDs, a single-cell transcriptomic atlas mapping early IVD formation is still lacking. Here, the authors generate a spatiotemporal and single cell-based transcriptomic atlas of human IVD formation at the embryonic stage and a comparative mouse transcript landscape. They identify two novel human notochord (NC)/nucleus pulposus (NP) clusters, SRY-box transcription factor 10 (SOX10)+ and cathepsin K (CTSK)+ , that are distributed in the early and late stages of IVD formation and they are validated by lineage tracing experiments in mice. Matrisome NC/NP clusters, T-box transcription factor T (TBXT)+ and CTSK+ , are responsible for the extracellular matrix homeostasis. The IVD atlas suggests that a subcluster of the vertebral chondrocyte subcluster might give rise to an inner annulus fibrosus of chondrogenic origin, while the fibroblastic outer annulus fibrosus preferentially expresseds transgelin and fibromodulin . Through analyzing intercellular crosstalk, the authors further find that notochordal secreted phosphoprotein 1 (SPP1) is a novel cue in the IVD microenvironment, and it is associated with IVD development and degeneration. In conclusion, the single-cell transcriptomic atlas will be leveraged to develop preventative and regenerative strategies for IVD degeneration.

Extraction of Keratin from Pig Nails and Electrospinning of Keratin/Nylon6 Nanofibers for Copper (II) Adsorption.

In this study, keratins were extracted from pig nail waste via the reduction method for the first time, using L-cysteine as the reductant and urea as the lytic agent. Nylon6 and pig nail keratin were successfully combined via electrospinning to generate a series of nylon6/pig nail keratin nanofibers with a variety of keratin concentrations (0% to 8%, w/w). From the results, it was found that the best concentration was 6% (w/w). The morphologies of the electrospun nanofibers were examined via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structural properties were characterized using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), and the thermal properties were described using thermo-gravimetric analysis (TGA). These results confirmed that the nanofibers were composed of both polymeric phases. Finally, copper (II) was used as a model ion, and the nanofiber membranes exhibited a strong adsorption affinity for metal ions in the water samples. This study provides an important foundation for the application of nanofiber membranes in metal adsorption.

M13, an anthraquinone compound isolated from Morinda officinalis promotes the osteogenic differentiation of MSCs by targeting Wnt/ß-catenin signaling.

BACKGROUND: Morinda officinalis (MO) is a herb used in Traditional Chinese Medicine (TCM) for the treatment of osteoporosis. M13, a MO-based anthraquinone compound is known to suppress osteoclast activity. However, whether M13 promotes MSCs osteogenic differentiation and its potential mechanism remains unknown. PURPOSE: To examine the influence of M13 on MSCs proliferation and osteogenic differentiation and elucidate the underlying mechanism. METHODS/STUDY DESIGNS: The effect of M13 exposure on MSCs proliferation was assessed via CCK8 assay, clone formation assay, immunofluorescence, RT-qPCR, and Western blot. The M13-mediated osteogenesis in vitro and ex vivo were evaluated via ALP and Alizarin red S staining, osteogenesis-associated gene (Runx2, Col1a1 and Opn) expression, and fetal limb explants culture. Molecular docking was employed for target signal pathway screening. The potential signaling mechanisms of M13-promoted MSCs osteogenic differentiation were analyzed by introducing XAV939 (Wnt/ß-catenin signaling inhibitor). RESULTS: M13 induced certain obvious positive effects on MSCs proliferation and osteogenic differentiation. Treatment with M13 enhanced MSCs viability and clone numbers. Meanwhile, M13 promoted osteogenic gene expression, enhanced ALP intensity and Alizarin red S staining in MSCs. In terms of mechanism, M13 strongly interacted with the docking site of the WNT signaling complex, thereby activating the Wnt/ß-catenin pathway. Furthermore, the M13-mediated osteogenic effect was partially inhibited by XAV939 both in vitro and ex vivo, which confirmed that the Wnt/ß-catenin axis is a critical regulator of M13-induced osteogenic differentiation of MSCs. CONCLUSION: Our study elucidated for the first time that M13 significantly promoted osteogenic differentiation of MSCs via stimulation of the Wnt/ß-catenin pathway in vitro and ex vivo.Our findings offered new additional evidence to support the MO or M13-based therapy of osteoporosis.

Keratin-Based Composite Bioactive Films and Their Preservative Effects on Cherry Tomato.

In this study, keratins were extracted from pig nail waste through the reduction method using L-cysteine as a reductant. Curcumin was successively incorporated in a mixed solution including keratin, gelatin, and glycerin to prepare different kinds of keratin/gelatin/glycerin/curcumin composite films. The morphology of the keratin/ gelatin/glycerin/curcumin composite films were examined using scanning electron microscopy. The structures and the molecular interactions between curcumin, keratin, and pectin were examined using Fourier transform infrared spectroscopy and X-ray diffraction, and the thermal properties were determined through thermogravimetric analysis. The tensile strengths of keratin/gelatin/glycerin/curcumin and keratin/gelatin/curcumin composite films are 13.73 and 12.45 MPa, respectively, and their respective elongations at break are 56.7% and 4.6%. In addition, compared with the control group (no film wrapped on the surface of tomato), the ratio of weight loss of the keratin (7.0%)/gelatin (10%)/glycerin (2.0%)/curcumin (1.0%) experimental groups is 8.76 ± 0.2%, and the hardness value of the tomatoes wrapped with composite films is 11.2 ± 0.39 kg/cm3. Finally, the composite films have a superior antibacterial effect against Staphylococcus aureus and Escherichia coli because of the addition of curcumin. As the concentration of curcumin reaches 1.0%, the antibacterial activity effect of the film is significantly improved. The diameter of the inhibition zone of E. coli is (12.16 ± 0.53) mm, and that of S. aureus is (14.532 ± 0.97) mm. The multifunctional keratin/gelatin/glycerin/curcumin bioactive films have great potential application in the food packaging industry.

Dihydroartemisinin Attenuated Intervertebral Disc Degeneration via Inhibiting PI3K/AKT and NF-κB Signaling Pathways.

Intervertebral disc degeneration (IDD) is the leading cause of low back pain (LBP). However, effective therapeutic drugs for IDD remain to be further explored. Inflammatory cytokines play a pivotal role in the onset and progression of IDD. Dihydroartemisinin (DHA) has been well reported to have powerful anti-inflammatory effects, but whether DHA could ameliorate the development of IDD remained unclear. In this study, the effects of DHA on extracellular matrix (ECM) metabolism and cellular senescence were firstly investigated in nucleus pulposus cells (NPCs) under tumor necrosis factor alpha (TNFα)-induced inflammation. Meanwhile, AKT agonist sc-79 was used to determine whether DHA exerted its actions through regulating PI3K/AKT and NF-κB signaling pathways. Next, the therapeutic effects of DHA were tested in a puncture-induced rat IDD model. Finally, we detected the activation of PI3K/AKT and NF-κB signaling pathways in clinical degenerative nucleus pulposus specimens. We demonstrated that DHA ameliorated the imbalance between anabolism and catabolism of extracellular matrix and alleviated NPCs senescence induced by TNFα in vitro. Further, we illustrated that DHA mitigated the IDD progression in a puncture-induced rat model. Mechanistically, DHA inhibited the activation of PI3K/AKT and NF-κB signaling pathways induced by TNFα, which was undermined by AKT agonist sc-79. Molecular docking predicted that DHA bound to the PI3K directly. Intriguingly, we also verified the activation of PI3K/AKT and NF-κB signaling pathways in clinical degenerative nucleus pulposus specimens, suggesting that DHA may qualify itself as a promising drug for mitigating IDD.

Hnrnpk maintains chondrocytes survival and function during growth plate development via regulating Hif1α-glycolysis axis.

The harmonious functioning of growth plate chondrocytes is crucial for skeletogenesis. These cells rely on an appropriate intensity of glycolysis to maintain survival and function in an avascular environment, but the underlying mechanism is poorly understood. Here we show that Hnrnpk orchestrates growth plate development by maintaining the appropriate intensity of glycolysis in chondrocytes. Ablating Hnrnpk causes the occurrence of dwarfism, exhibiting damaged survival and premature differentiation of growth plate chondrocytes. Furthermore, Hnrnpk deficiency results in enhanced transdifferentiation of hypertrophic chondrocytes and increased bone mass. In terms of mechanism, Hnrnpk binds to Hif1a mRNA and promotes its degradation. Deleting Hnrnpk upregulates the expression of Hif1α, leading to the increased expression of downstream glycolytic enzymes and then exorbitant glycolysis. Our study establishes an essential role of Hnrnpk in orchestrating the survival and differentiation of chondrocytes, regulating the Hif1α-glycolysis axis through a post-transcriptional mechanism during growth plate development.

Description of Prasinibacter corallicola gen. nov., sp. nov., a zeaxanthin-producing bacterium isolated from stony coral Porites lutea.

Thermal stress is considered one of the main causes of mass scleractinian coral degradation; however, it is still unknown how corals can adapt to future global warming. In this study, 11 strains of coral-associated Flavobacteria were shown to produce zeaxanthin, a carotenoid antioxidant, which may help coral holobionts to alleviate thermal stress. In addition, a novel zeaxanthin-producing Flavobacterium, designated R38T, was identified using polyphasic taxonomy. Although strain R38T shared a maximum 16S rRNA gene sequence similarity of 93% with Mesoflavibacter aestuarii KYW614T, phylogenetic analyses based on whole genome and 16S rRNA gene sequences revealed that strain R38T forms a distinct branch in a robust cluster composed of strain R38T and Leptobacterium flavescens KCTC 22160T under the family Flavobacteriaceae. Strain R38T exhibited average nucleotide identities of 70.2% and 72.5% for M. aestuarii KYW614T and L. flavescens KCTC 22160T, respectively. The only detected respiratory quinone was menaquinone 6 (MK-6). The genomic DNA G + C content was 33.2 mol%. The major polar lipids were phosphatidylmethylethanolamine, phosphatidylethanolamine, one unidentified ninhydrin phospholipid, three unidentified ninhydrin-positive lipids, and three unidentified lipids. The major cellular fatty acids were iso - C15: 0, iso - C15: 0 ω6c, C16:2 DMA, and C13:1 ω3c. The distinct biochemical, chemotaxonomic, phylogenetic, and phylogenomic differences from validly published taxa suggest that strain R38T represents a new species of a new genus, for which Prasinibacter corallicola gen. nov., sp. nov. is proposed. The type strain R38T (= MCCC 1K03889T = KCTC 72444T).

Self-amplifying loop of NF-κB and periostin initiated by PIEZO1 accelerates mechano-induced senescence of nucleus pulposus cells and intervertebral disc degeneration.

Abnormal mechanical load is a main risk factor of intervertebral disc degeneration (IDD), and cellular senescence is a pathological change in IDD. In addition, extracellular matrix (ECM) stiffness promotes human nucleus pulposus cells (hNPCs) senescence. However, the molecular mechanism underlying mechano-induced cellular senescence and IDD progression is not yet fully elucidated. First, we demonstrated that mechano-stress promoted hNPCs senescence via NF-κB signaling. Subsequently, we identified periostin as the main mechano-responsive molecule in hNPCs through unbiased sequencing, which was transcriptionally upregulated by NF-κB p65; moreover, secreted periostin by senescent hNPCs further promoted senescence and upregulated the catabolic process in hNPCs through activating NF-κB, forming a positive loop. Both Postn (encoding periostin) knockdown via siRNA and periostin inactivation via neutralizing antibodies alleviated IDD and NPCs senescence. Furthermore, we found that mechano-stress initiated the positive feedback of NF-κB and periostin via PIEZO1. PIEZO1 activation by Yoda1 induced severe IDD in rat tails without compression, and Postn knockdown alleviated the Yoda1-induced IDD in vivo. Here, we reported for the first time that self-amplifying loop of NF-κB and periostin initiated via PIEZO1 under mechano-stress accelerated NPCs senescence, leading to IDD. Furthermore, periostin neutralizing antibodies, which may serve as potential therapeutic agents for IDD, interrupted this loop.

Microbiome of juvenile corals in the outer reef slope and lagoon of the South China Sea: insight into coral acclimatization to extreme thermal environments.

Environmental conditions between the outer reef slope (ORS) and lagoon in tropical atolls are significantly different, but the variations of juvenile coral-microbiomes in the two environments and their relationship with coral thermal acclimatization are poorly understood. We explored this issue based on local water conditions and the microbiome of juvenile corals in the ORS and lagoon in the central South China Sea. Coral-symbiotic Symbiodiniaceae showed significant differences among coral species; Pocillopora verrucosa and Pachyseris rugosa in the ORS, and Acropora formosa in the lagoon were dominated by Durusdinium, but other corals were dominated by Cladocopium. Although A. formosa in the ORS were dominated by Cladocopium (C3u), they were dominated by Durusdinium (D1/D1a) and Cladocopium (C50) in the lagoon. Other coral species were both dominated by Cladocopium in the lagoon and ORS. The relative abundance of bacteria in the Deinococcus-Thermus was generally higher in the lagoon corals than in the ORS corals. Our study indicates that P. verrucosa, P. rugosa and Porites lutea may have high thermal tolerance based on the relatively high abundance of heat-tolerant Durusdinium and Thermus scotoductus. Likewise, A. formosa in the lagoon may acclimatize to the thermal environment based on a high relative abundance of heat-tolerant Durusdinium.