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The discovery of graphene has inspired extensive interest in two-dimensional ( 2D) materials, and has led to synthesis/growth of additional 2D materials, generally referred to as 'Beyond Graphene'. Notable among the recently discovered exotic 2D materials are group IV elemental monolayers silicene and germanene, group V elemental monolayer phosphorene, and binary monolayers, such as hexagonal boron nitride ( h- BN), and molybdenum disulfide ( MoS2 ). Environmental effect on the physical and chemical properties of these 2D materials is a fundamental issue for their practical applications in devices operating under ambient conditions, especially, exposure to air often leads to oxidation of nanomaterials with significant impact on the functional properties and performances of devices built with them. In view of its importance, we present here a review of the recent experimental and theoretical studies on the oxidation of 2D materials focusing on the relationship between the oxidation process and the energy values which can be calculated by first principles methods. The complement of experiments and theory facilitates the understanding of the underlying oxidation process in terms of cohesive energy, energy barrier to oxidation and dissociation energy of oxygen molecule for 2D materials including graphene, silicene, germanene, phosphorene, h- BN, and MoS2. WIREs Comput Mol Sci 2017, 7:e1280. doi: 10.1002/wcms.1280 For further resources related to this article, please visit the . [ABSTRACT FROM AUTHOR]

Abstract: Co92Zr8(50nm)/Ag(x) soft magnetic films have been prepared on Si (111) substrates by oblique sputtering at 45°. Nanoparticle size of Co92Zr8 soft magnetic films can be tuned by thickening Ag buffer layer from 9nm to 96nm. The static and dynamic magnetic properties show great dependence on Ag buffer layer thickness. The coercivity and effective damping parameter of Co92Zr8 films increase with thickening Ag buffer layer. The intrinsic and extrinsic parts of damping were extracted from the effective damping parameter. For x=96nm film, the extrinsic damping parameter is 0.028, which is significantly larger than 0.004 for x=9nm film. The origin of the enhancement of extrinsic damping can be explained by increased inhomogeneity of anisotropy. Therefore, it is an effective method to tailor magnetic damping parameter of thin magnetic films, which is desirable for high frequency application. [Copyright &y& Elsevier]

Micropterus salmoides rhabdovirus (MSRV) is a formidable pathogen, presenting a grave menace to juvenile largemouth bass. This viral infection frequently leads to epidemic outbreaks, resulting in substantial economic losses within the aquaculture industry. Unfortunately, at present, there are no commercially available vaccines or pharmaceutical treatments to combat this threat. In order to address the urgent need for therapeutic strategy to resist MSRV infection, the antiviral activity of natural product honokiol against MSRV was explored in this study. Firstly, cellular morphology was directly observed in an inverted microscope when treated with honokiol after MSRV infection. The results clarified that honokiol significantly lessened cytopathic effect (CPE) induced by MSRV and protected the integrity of GCO cells. Furthermore, the viral nucleic acid expression (G gene) was detected by reverse transcription real‐time quantitative PCR (RT‐qPCR) and the results indicated that honokiol significantly decreased the viral loads of MSRV in a concentration‐dependent manner, and honokiol showed a high antiviral activity with IC50 of 2.92 μM. Besides, honokiol significantly decreased the viral titre and suppressed apoptosis caused by MSRV. Mechanistically, honokiol primarily inhibited the initial replication of MSRV and discharge of progeny virus to exert anti‐MSRV activity. More importantly, in vivo experiments suggested that honokiol (40 mg/kg) expressed a fine antiviral activity against MSRV when administrated with intraperitoneal injection, which led to a notable 40% improvement in the survival rate among infected largemouth bass. In addition, it also resulted in significant reduction in the viral nucleic acid expression within liver, spleen and kidney at 2, 4 and 6 days following infection. What is more, 100 mg/kg honokiol with oral administration also showed certain antiviral efficacy in MSRV‐infected largemouth bass via improving the survival rate by 10.0%, and decreasing significantly the viral nucleic acid expression in liver, spleen and kidney of largemouth bass on day 2. In summary, natural product honokiol is a good candidate to resist MSRV infection and has promising application prospects in aquaculture. [ABSTRACT FROM AUTHOR]

Topmouth culter (Culter alburnus) is an ecologically and economically important species belonging to the subfamily Culterinae that is native to and widespread in East Asia. Intraspecific variation of semi‐buoyant and adhesive eggs in topmouth culter provides an ideal opportunity to investigate the genetic mechanisms of spawning habits underlying the adaptive radiation of cyprinids in East Asia. In this study, we present a chromosome‐level genome assembly of topmouth culter and re‐sequenced 158 individuals from six locations in China covering three geographical groups and two egg type variations. The topmouth culter genome size was 1.05 Gb, with a contig N50 length of 17.8 Mb and anchored onto 24 chromosomes. Phylogenetic analysis showed that the divergence time of the Culterinae was coinciding with the time of initiation of the Asian monsoon intensification. Gene family evolutionary analysis indicated that the expanded gene families in topmouth culter were associated with dietary adaptation. Population‐level genetic analysis indicated clear differentiation among the six populations, which were clustered into three distinct clusters, consistent with their geographical divergence. The historical effective population size of topmouth culter correlated with the Tibetan Plateau uplifting according to the demographic history reconstruction. A selective sweep analysis between adhesive and semi‐buoyant egg populations revealed the genes associated with the hydration and adhesiveness of eggs, indicating divergent selection towards different hydrological environments. This study offers a high‐resolution genetic resource for further studies on evolutionary adaptation, genetic breeding and conservation of topmouth culter, providing insights into the molecular mechanisms for egg type variation of East Asian cyprinids. [ABSTRACT FROM AUTHOR]

Redox potential is a key environmental indicator in the gut and also significantly affects host health. To study the influence of gut redox potential on the infection of hosts by pathogen, we employed zebrafish and common carp as animal models to investigate the relationship between gut redox potential and host susceptibility. Our results proved that gut redox potential was significantly elevated after host infection with pathogenic bacteria. Moreover, the level of reactive oxygen species (ROS) was significantly and positively correlated with gut redox potential. Reduction of the gut redox potential with antioxidants significantly improved host resistance to pathogen infections. In addition, when the host was infected with pathogen, the reduction of gut redox potential could improve survival. Interestingly, the combination of antioxidants and low concentrations of antibiotics could achieve a similar therapeutic effect to that of a single high concentration of antibiotics by reducing the gut redox potential. Overall, this study proved that altered redox potential could aid in the host resistance to infection, and also provides new perspectives for the treatment of pathogen infections. [Display omitted] • Gut redox potential was significantly elevated after host infection with pathogenic bacteria. • Reduction of the gut redox potential significantly improved host resistance to pathogen infections. • The combination of antioxidants and low concentrations of antibiotics improved host resistance to pathogen infections. [ABSTRACT FROM AUTHOR]

Largemouth bass (Micropterus Salmoides) is an important cultured fish in south China with a large scale of cultivation. However, bacterial disease has badly damaged the healthy development of the breeding industry. Nocardia Seriolae (N. seriolae), a gram-positive bacterial widely existing in soil and water, mainly infects bass and snakehead. This bacterial has caused a large financial loss in China. However, efficient methods to control this pathogeny still remain largely unexplored. Previous study suggested that vaccine was efficient method to prevent fish from bacterial infection. In this study, based on reverse vaccinology, a new DNA vaccine named pcDNA-ABP was obtained by genetic engineering technology. Furthermore, to enhance the stability and target ability, mannosylated chitosan (Mcs) was used to package the nucleic acid vaccine. In order to evaluate the immunoprotection effect of this vaccine, a total of 300 fish (N = 5) were vaccinated with PBS (50 μL per fish), pET32a-ABP (10 μg per fish), pcDNA (10 μg per fish), pcDNA-ABP (20 μg per fish), Mcs-pcDNA-ABP (20 μg per fish). After 28 days' vaccination, experiment fish were challenged with live N. seriolae. Then, some immune-related indexes were measured to evaluate the variation of fish's immunity. Results showed the highest relative percentage survival (RPS) was 80.73% in Mcs-pcDNA-ABP group. What's more, the serum antibody titer, enzyme activity in vaccinated group were significantly increased compared to that of control group. Furthermore, some innate immune-related genes (IL-1β , CD4 , TNF-α) and adaptive immune-related gene (IgM) were significantly up-regulated in kidney and spleen. In a word, in this study, a new DNA vaccine packaged with mannosylated chitosan was developed. Results suggested that this vaccine could significantly enhance the immunity of fish after vaccination, and increase the survival rate after live bacterial infection. This research might provide some basic information for the development of N. seriolae vaccine, and make a contribution to the control of bacterial diseases in aquaculture. • A novel antigen ABP was screened from membrane proteins of Nocardia Seriolae via reverse vaccinology. • The DNA vaccine loaded by mannosylated chitosan nanoparticles was developed by genetic engineering technology and materials technology. • DNA vaccine effectively induced immune response and provided effective immunoprotection against bacterial infection. • Mannosylated chitosan served as the vaccine carrier enhanced the effect of this vaccine. [ABSTRACT FROM AUTHOR]

Protection of free-electron sources has been technically challenging due to lack of materials that transmit electrons while preventing corrosive gas molecules. Two-dimensional materials uniquely possess both of required properties. Here, we report three orders of magnitude increase in active pressure and factor of two enhancement in the lifetime of high quantum efficiency (QE) bialkali photocathodes (cesium potassium antimonide (CsK2Sb)) by encapsulating them in graphene and thin nickel (Ni) film. The photoelectrons were extracted through the graphene protection layer in a reflection mode, and we achieved QE of ~ 0.17% at ~ 3.4 eV, 1/e lifetime of 188 h with average current of 8.6 nA under continuous illumination, and no decrease of QE at the pressure of as high as ~ 1 × 10–3 Pa. In comparison, the QE decreased drastically at 10–6 Pa for bare, non-protected CsK2Sb photocathodes and their 1/e lifetime under continuous illumination was ~ 48 h. We attributed the improvements to the gas impermeability and photoelectron transparency of graphene. [ABSTRACT FROM AUTHOR]

Chilodonella , a parasitic ciliate that infects both cold water and warm water fish, can impede the growth of juvenile fish and cause considerable economic losses globally to freshwater aquaculture. In this study, the parasite was collected from both the gills and zygotes of largemouth bass (Micropterus salmoides). Isolated from diseased fish, the parasites were identified as Chilodonella uncinata based on morphological features and genetical diagnostic characterization using the partial small subunit ribosomal RNA gene. To develop an effective approach to treat chilodonellosis caused by C. uncinata in largemouth bass farming, we first developed an in vivo culture model for propagating C. uncinate and thus could use for morphological characterization, molecular analyses and antiparasitic drug screening. Curcumin was successfully identified as an efficacious anti - C. uncinata agent from 26 phytochemical compounds. When administered at a concentration of 6 mg/L, curcumin not only completely cured infected largemouth bass but also shielded uninfected fish from C. uncinata infections. The 24 h median effective concentration (EC 50) of curcumin against C. uncinata was 3.098 mg/L. Remarkably, the 96 h median lethal concentration (LC 50) of curcumin against largemouth bass was determined to be 17.143 mg/L, approximately 5.533 times higher than EC 50. The mechanism of action of curcumin was investigated by the cellular thermal shift assay, demonstrating that tubulin alpha chain was the binding target for curcumin. Moreover, SEM investigations further provided morphological evidence suggesting that curcumin induces parasite demise by disrupting the parasite's body surface and subsequently infiltrating its interior. These findings collectively emphasize the potential of curcumin as a safe and effective therapeutic agent for controlling C. uncinata in aquaculture. [Display omitted] • Anti - Chilodonella uncinate screening of 26 phytochemical compounds showed curcumin has an efficacious bioactivity. • The 24 h EC 50 and 96 h LC 50 of curcumin against C. uncinate was 3.098 mg/L and 17.143 mg/L, respectively. • Cellular thermal shift assay combined with mass spectrometry identified 8 possible drug targets of curcumin. • Molecular docking of curcumin with tubule alpha chain tba-5 indicated the strong binding energy (−8.57 kJ/mol) and 6 favorable hydrogen bonds. [ABSTRACT FROM AUTHOR]

Bacillus genus, particularly Bacillus velezensis , is increasingly considered as viable alternatives to antibiotics in aquaculture due to their safety and probiotic potential. However, the specific mechanisms through which probiotic B. velezensis confers protection against Aeromonas hydrophila infection in fish remain poorly understood. This study delved into the multifaceted impacts of B. velezensis BV1704–Y on diverse facets of zebrafish health, including gut barrier function, immune response, oxidative stress, gut environment, microbiome composition, and disease resistance. Our findings demonstrate that supplementation with B. velezensis BV1704–Y significantly alleviated symptoms and reduced mortality in zebrafish infected with A. hydrophila. Furthermore, a notable reduction in the expression of pivotal immune-related genes, such as IL-1β , IL6 , and TNF-α , was evident in the gut and head kidney of zebrafish upon infection. Moreover, B. velezensis BV1704–Y supplementation resulted in elevated activity levels of essential antioxidant enzymes, including SOD, CAT, and GSH, in gut tissue. Notably, B. velezensis BV1704–Y positively modulated the structure and function of the intestinal microbiome, potentially enhancing immune response and resilience in zebrafish. Specifically, supplementation with B. velezensis BV1704–Y promoted the relative abundance of beneficial bacteria, such as Cetobacterium , which showed a noteworthy negative correlation with the expression of pro-inflammatory genes and a positive correlation with gut barrier-related genes. Altogether, our study suggests that B. velezensis BV1704–Y holds promise as an effective probiotic for protecting zebrafish against A. hydrophila infection, offering potential benefits for the aquaculture industry. • B. velezensis BV1704–Y reduces mortality in A. hydrophila -infected zebrafish. • B. velezensis BV1704–Y supplementation enhanced immunity and antioxidant capacity. • B. velezensis BV1704–Y positively modulated the composition and function of the gut microbiome. • Cetobacterium regulated by B. velezensis BV1704–Y contribute to improved gut barrier function and reduced inflammation. [ABSTRACT FROM AUTHOR]

Gyrodactylosis is a widespread parasitic illness that affects fish in both farming and natural environments. The current chemotherapy approaches are not always satisfactory, so the development of new anthelmintic agents is necessary. Arctigenin, a natural lignan found in various plants, possesses a multitude of biological activities. Previous research has demonstrated that arctigenin targets the protein myosin in Gyrodactylus kobayashii. Building upon this interaction, we designed 31 derivatives of arctigenin using Discovery Studio. The ester derivatives exhibited significant anthelmintic activity, with C-21 displaying the highest activity, boasting an EC 50 of 0.4 mg/L. Furthermore, we conducted an investigation into the mechanism by which C-21 affects the parasite and discovered that it disrupts the muscular structure of the parasite's body surface, thus inhibiting its energy production and myosin expression, ultimately leading to the parasite's demise. In conclusion, C-21 exhibits promising potential as an agent for controlling Gyrodactylus kobayashii infection. [Display omitted] • 31 arctigenin derivatives were designed based on the targets, eight of which were synthesized for the first time. • The ester arctigenin derivatives have good anthelmintic activity. • Arctigenin derivative 21 inhibits Gyrodactylus kobayashii energy supply by destroying body surface structures and inhibiting myosin expression, which ultimately leads to parasite death. [ABSTRACT FROM AUTHOR]

Largemouth bass virus (LMBV) causes high mortality and large economic losses in largemouth bass aquaculture. However, effective antiviral candidates against LMBV infection are currently lacking. This study reported the significant inhibitory effect of berberine (BBR) on LMBV proliferation in epithelioma papulosum cyprinid (EPC) cells, with an IC 50 of 14.72 μM. Moreover, the ubstantial reduction in virus titration and inhibition of LMBV-induced CPE by BBR, indicated its potent in vitro antiviral activity. Further exploration of the antiviral mechanism of BBR revealed that BBR induced apoptosis in virus-infected cells 6 h post-infection, thereby suppressing LMBV proliferation, as evidenced by flow cytometry and transmission electron microscopy. Additionally, BBR reduced the mitochondrial membrane potential (Δ Ψ m) in infected cells, thereby activating downstream effector proteins, such as caspase-9 and caspase-3, as demonstrated by Δ Ψ m measurement and western blot analysis. In vivo experiments showed that the intraperitoneal injection of BBR (3.93 mg/kg) effectively enhanced the survival of LMBV-infected fish (15%). Also, the histopathology and viral load detection demonstrated that BBR significantly inhibited LMBV replication in vivo. Overall, this study provided a valuable reference for further understanding the intricate interplay between LMBV and cellular apoptosis as well as developing apoptosis-based anti-LMBV therapeutics. • BBR exhibited significant inhibition of LMBV proliferation in EPC cells. • BBR inhibited LMBV proliferation by activating the mitochondrial apoptotic pathway during early stages of infection. • BBR effectively improved survival rate of LMBV-infected largemouth bass and significantly reduced viral load and tissue damage within the fish. [ABSTRACT FROM AUTHOR]

Iridovirus can cause a mass of death in grouper, leading to huge economic loss in recent years. At present, practical vaccine is still the best way to control the outbreak of this virus. Many researches had indicated that the major capsid protein (MCP) of grouper iridovirus of Taiwan (TGIV) is an effective antigen to induce a specific immune response in grouper. However, these traditional vaccines that based on large proteins or whole organisms are faced with challenges because of the unnecessary antigenic load. Thus, in this study, we screened the dominant linear epitope within the MCP of TGIV and then, a new peptide vaccine (P2) was developed via prokaryotic expression system. Furthermore, SWCNTs was used as a vaccine carrier to enhance the immunoprotective effect. To evaluate the immunoprotective effect of this vaccine, a total of 245 fish were vaccinated with P2 (5, 10, 20 mg L−1) and SWCNTs-P2 (5, 10, 20 mg L−1) via immersion before being challenged with live TGIV at 28 days post immunization (d.p.i.). Results showed that the serum antibody titer, enzymatic activity, expression level of some immune-related genes (CC chemokine, IgM and TNF-α) and survival rate were significantly increased (SWCNTs-P2, 20 mg L−1, 100%) compared to the control group (0%). These results indicated that this peptide vaccine could effectively induce specific immune response in vaccinated groupers. Functionalized SWCNTs could serve as a carrier of the peptide vaccine to enhance the immunoprotective effect via immersion. To sum up, epitope screening might be a potential way to develop an effective vaccine nowadays, and SWCNTs might provide a practical method that can be used in large-scale vaccination, especially for juvenile fish, to fight against diseases in aquaculture industry. • The dominant linear epitope within the MCP of TGIV was screened, and a new peptide vaccine was obtained via prokaryotic expression system. • Peptide vaccine P2 can effectively induce specific immune response in grouper. • Immune-related indicators significantly enhanced post vaccination with P2 and SWCNTs-P2. • SWCNTs significantly improve the immunoprotective effect of P2 in immersion immunization. [ABSTRACT FROM AUTHOR]

Diseases caused by pathogens severely hampered the development of aquaculture, especially largemouth bass virus (LMBV) has caused massive mortality and severe economic losses to the culture of largemouth bass (Micropterus salmoides). Considering the environmental hazards and human health, effective and environmentally friendly therapy strategy against LMBV is of vital importance and in pressing need. In the present study, a novel nanobody (NbE4) specific for LMBV was selected from a phage display nanobody library. Immunofluorescence and indirect ELISA showed that NbE4 could recognize LMBV virions and had strong binding capacity, but RT-qPCR evidenced that NBE4 did not render the virus uninfectious. Besides, antiviral drug ribavirin was used to construct a targeted drug system delivered by bacterial nanocellulose (BNC). RT-qPCR revealed that NbE4 could significantly enhance the antiviral activity of ribavirin in vitro and in vivo. The targeted drug delivery system (BNC-Ribavirin-NbE4, BRN) reduced the inflammatory response caused by LMBV infection and improved survival rate (BRN-L, 33.3 %; BRN-M, 46.7 %; BRN-H, 56.7 %)compared with control group (13.3 %), ribavirin group (RBV, 26.7 %) and BNC-ribavirin (BNC-R, 40.0 %), respectively. This research provided an effective antiviral strategy that improved the drug therapeutic effect and thus reduced the dosage. • A novel nanobody (NbE4) specific for largemouth bass virus (LMBV) was selected. • NbE4 can enhance the antiviral effect of ribavirin against LMBV by targeting effects. • The nano targeted drug system can improve the survival rate of LMBV-infected fish. • The treatment means reduced the inflammatory response caused by LMBV infection. [ABSTRACT FROM AUTHOR]

Host-derived probiotics are microorganisms sourced from the host's gut environment, aimed at enhancing growth and overall health. Given the increasing stringency in the regulation of antibiotics within animal production, the adoption of in-feed probiotics has emerged as a compelling antibiotic alternative in aquaculture. Here, we investigate the impact of Pseudomonas monteilii JK-1 on the growth performance and disease resistance of grass carp (Ctenopharyngodon idella). The results indicate that P. monteilii JK-1 leads to a significant increase in weight gain (WG), specific growth rate (SGR), and survival rate, along with a substantial reduction in pathogen load (Aeromonas) (P < 0.05). Furthermore, we observed a noteworthy improvement in the expression of key immune-related genes, including interleukin 1β (IL-1β), interleukin 10 (IL10), tumor necrosis factor alpha (TNF-α), and transforming growth factor beta (TGF-β) in both the head kidney and gut (P < 0.05). This effect extends to the augmentation of the activities of crucial antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in both liver and gut tissues (P < 0.05). Notably, P. monteilii JK-1 exerts a positive influence on the complexity of the gut microbiome ecological network. In this context, Cetobacterium emerges as a keystone microbiota responsible for maintaining interspecies interactions and enhancing gut network stability. Moreover, our study establishes a positive connection between Cetobacterium and growth performance and between Akkemansia and immune response, respectively. In addition, the result of partial least squares path model (PLS-PM) showed that P. monteilii JK-1 does not directly enhance growth performance and pathogen resistance but does so by regulating keystone taxa and promoting gut network stability. Collectively, this study offers a nuanced comprehension of how probiotics enhance growth and boost disease resistance, focusing on the gut microbial ecological network. These findings showed that P. monteilii JK-1 has potential application as a probiotic in grass carp, which may provide a new strategy of preventing and controlling bacterial diseases in this species. • P. monteilii JK-1 supplementation enhanced immunity and antioxidant capacity. • Dietary P. monteilii JK-1 decreased the Aeromonas load in liver and gut, and enhanced the survival rate of grass carp. • P. monteilii JK-1 enhanced the complexity and stability of gut microbiome ecological network. • The microbes affected by P. montelli JK-1 were correlated with the growth performance and pathogen resistance of grass carp. [ABSTRACT FROM AUTHOR]

Monogenea, a prevalent parasite in aquaculture, poses significant threats to the industry, leading to substantial losses. Current preventive measures have proven insufficient, necessitating the development of novel and effective anti-parasitic drugs. In this investigation, we obtained the full-length myosin cDNA sequence by analyzing three-generation transcriptome data, revealing a 5817-base sequence encoding 1938 amino acids. Subsequently, we modeled and analyzed the characteristics of the secondary and tertiary of myosin, pinpointing the crucial functional region within the motor domain (amino acids 1–768). The prokaryotic expression of this domain yielded a protein of 87.44 kDa, confirmed as myosin by Western Blotting. Molecular docking identified ASN439 as the key amino acid residue involved in arctigenin and myosin binding, a result corroborated by site-directed mutagenesis, affirming the active cavity of this interaction. Chalcone and shikonin were chosen from a virtual sieve of molecular library of natural drugs based on the active cavity. Chalcone and shikonin exhibited EC 50 values of 1.085 mg/L and 0.371 mg/L, respectively, with corresponding IC 50 values for myosin of 0.44 mM and 0.14 mM. Given its superior activity and structure, shikonin was selected for further optimization of drug molecule design, culminating in the discovery of 1,4-naphthoquinone as a potent antiparasitic agent. This compound demonstrated an EC 50 of 0.047 mg/L, LC 50 of 0.23 mg/L, and a TI index of 4.893. These findings collectively highlight the potential of shikonin and 1,4-naphthoquinone as alternative compounds to control Gyrodactylus infections. Further optimization of medicinal chemistry holds promise for the development of more potent 1,4-naphthoquinone analogues, offering prospects for future anthelmintic control through combinatorial or replacement strategies. Through molecular docking and site-directed mutagenesis, the binding activity of arctigenin with myosin was verified. Subsequently, shikonin, a potent antiparasitic agent and myosin inhibitor, has been identified through virtual screening techniques. Using shikonin as a lead compound, a series of derivatives were designed, ultimately leading to the discovery of 1,4-naphthoquinone, a highly effective anti-parasitic drug. [Display omitted] • Arctigenin effectively eradicates parasites by acting as a potent inhibitor of myosin. • Shikonin, an effective myosin inhibitor, has been identified by drug virtual screening. • Shikonin stands out as a highly potent small molecule with antiparasitic properties. • 1,4-naphthoquinone serves as a highly potent antiparasitic agent. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (GNPs) are one of the most widely used nanomaterials in various fields. Especially, the unique chemical and physical properties make them as the promising candidates in drug target identification, unfortunately, little is known about their application in parasites. In this paper, GNPs were employed as new solid support to identify drug targets of natural bioactive compound arctigenin (ARG) against fish monogenean parasite Gyrodactylus kobayashi. Before target identification, GNPs with ARG on the surface showed the ability to enter the live parasites even the nucleus or mitochondria, which made the bound compounds capable of contacting directly with target proteins located anywhere of the parasites. At the same time, chemically modified compound remained the anthelminthic efficacy against G. kobayashii. The above results both provide assurance on the reliability of using GNPs for drug target-binding specificity. Subsequently, by interrogating the cellular proteome in parasite lysate, myosin-2 and UNC-89 were identified as the potential direct target proteins of ARG in G. kobayashii. Moreover, results of RNA-seq transcriptomics and iTRAQ proteomics indicated that myosin-2 expressions were down-regulated after ARG bath treatment both in transcript and protein levels, but for UNC-89, only in mRNA level. Myosin-2 is an important structural muscle protein expressed in helminth tegument and its identification as our target will enable further inhibitor optimization towards future drug discovery. Furthermore, our findings demonstrate the power of GNPs to be readily applied to other parasite drugs of unknown targets, facilitating more broadly therapeutic drug design in any pathogen or disease model. [ABSTRACT FROM AUTHOR]

Rap1 (Ras-related protein 1), as a member of the Ras-like small GTP binding protein family, involves in the regulation of cell life activities and mediates a variety of biological events including cell junctions, cell polarity, cell proliferation and differentiation by binding to GDP/GTP. In addition, Rap1 also plays an important role in innate immune response by regulating the adhesion, diffusion and migration of white blood cells. However, it is still unclear how Rap1 affects the innate immunity of teleost fish against bacterial infections. In this study, we amplified the Rap1 from tilapia and conducted the sequence analysis of Rap1 nucleotide and amino acid sequences, then characterized its tissue distribution and expression pattern in response to pathogen infection in tilapia for the first time, and explored the bacteriostatic and bacterial binding effects of Rap1. The results showed that the Rap1 possessed a whole open reading frame (ORF) with 558 bp, encoding 185 amino acids. The Rap1 protein was highly homologous with Rap1 from other species. Conserved domain analysis revealed that Rap1 contained five G box domains that mediated its binding to ornithine. Rap1 mRNA was widely expressed in tilapia tissues, and the highest level was found in spleen. Under Streptococcus agalactiae (S. agalactiae) infection, the expression of Rap1 was significantly up-regulated in head kidney and brain. In addition, the recombinant protein Rap1 hold the ability binding to S. agalactiae and inhibit the proliferation of S. agalactiae. In conclusion, this study not only provided a reference for exploring the function of Rap1 in teleost against pathogen infection, but also enriched the basic theoretical research of Rap1 function and antibacterial immune response in teleost. • Rap1 was widely distributed in tilapia tissues, with the highest abundance in spleen. • The expression of Rap1 was significantly up-regulated in head kidney and brain after Streptococcus agalactiae challenge. • rRap1 hold the ability to bind to bacteria and reduce bacterial proliferation. [ABSTRACT FROM AUTHOR]

Natural products have gained recognition as a valuable resource and have significant implications in the field of aquaculture. Nevertheless, the limited water solubility of drugs, leading to compromised bioavailability, has been a persistent challenge in the realm of pharmaceutical research. Magnolol as a natural product, the low solubility leads to limited activity against Ichthyophthirius multifiliis , which severely limits the application of magnolol. Nanosuspensions are considered to be an important strategy to improve the solubility and bioavailability of insoluble drugs. The purpose of this study is to fabricate nanosuspensions that can effectively improve the solubility and antiparasitic activity of magnolol. Magnolol nanosuspensions (MNs) containg Pluronic F68 as a stabilizer was prepared by the solvent-antisolvent precipitation method. The results of TEM, DSC and FTIR analysis showed that the surfactant attached to the surface of magnolol, and the nanosuspensions process significantly reduced the crystallinity and improved the solubility and dissolution rate of magnolol. The Central Composite Design was adopted to investigate the effects of independent variables viz. amount of temperature (A), the ratio of pluronic F68 to magnolol (w /w) (B), and churning time (C) on particle size (Y), obtaining optimum nanosuspensions with a size of 32.03 nm. Compared with free magnolol, the release rate of magnolol in 119 nm and 35 nm MNs was significantly improved, and the release rate of magnolol was increased from 28.13% to 58.45% and 85.70% within 60 min. Further, the antiparasitic activity of MNs was measured. The results showed the reduction in drug particle size leads to an enhancement in the insecticidal activity of magnolol. Altogether, this study proposes a promising strategy to enhance activity by increasing the solubility of natural products. • This study proposed a nanosuspensions strategy to improve the water solubility and activity for natural products (magnolol). • Through the preparation of nanosuspensions, the particle size of magnolol is reduced to the nanoscale. • Nanosuspensions with small particle sizes have higher stability and faster release speed • The nanosuspensions technology significantly enhanced the antiparasitic effects against I. multifiliis in vivo. [ABSTRACT FROM AUTHOR]

Streptococcosis is a highly contagious aquatic bacterial disease that poses a significant threat to tilapia. Vaccination is a well-known effective measure to prevent and control fish bacterial diseases. Among the various immunization methods, immersion vaccination is simple and can be widely used in aquaculture. Besides, nanocarrier delivery technology has been reported as an effective solution to improve the immune effect of immersion vaccine. In this study, the surface immunogenic protein (Sip) was proved to be conserved and potential to provide cross-immunoprotection for both Streptococcus agalactiae (S. agalactiae) and Streptococcus iniae (S. iniae) by multiple sequences alignment and Western blotting analysis. On this basis, we expressed and obtained the recombinant protein rSip and connected it with functionalized carbon nanotubes (CNT) to construct the nanocarrier vaccine system CNT-rSip. After immersion immunization, the immune effect of CNT-rSip against above two streptococcus infections was evaluated in tilapia based on some aspects including the serum specific antibody level, non-specific enzyme activities, immune-related genes expression and relative percent survival (RPS) after bacteria challenge. The results showed that compared with control group, CNT-rSip significantly (P < 0.05) increased the serum antibody levels, related enzyme activities including acid phosphatase, alkaline phosphatase, lysozyme and total antioxidant capacity activities, as well as the expression levels of immune-related genes from 2 to 4 weeks post immunization (wpi), and all these indexes peaked at 3 wpi. Besides, the above indexes of CNT-rSip were higher than those of rSip group with different extend during the experiment. Furthermore, the challenge test indicated that CNT-rSip provided cross-immunoprotection against S. agalactiae and S. iniae infection with RPS of 75 % and 72.41 %, respectively, which were much higher than those of other groups. Our study indicated that the nanocarrier immersion vaccine CNT-rSip could significantly improve the antibody titer and confer cross-immuneprotection against S. agalactiae and S. iniae infection in tilapia. • CNT-rSip highly induced serum antibody production. • CNT-rSip prominently promoted the expression levels of immune-related genes. • CNT-rSip significantly enhanced the related enzyme activities. • CNT-rSip significantly confered cross-immuneprotection against S. agalactiae and S. iniae infection in tilapia. [ABSTRACT FROM AUTHOR]

Gyrodactylosis causes fish to be infected by other harmful pathogens, resulting in high mortality rates and serious economic losses to the aquaculture industry. Currently, unapproved chemicals are the main reliance for gyrodactylosis treatment, which is not always satisfactory. Targeted selection of compounds that destroy the epidermal structure of the parasite becomes an ideal strategy for parasites control. Therefore, glacial acetic acid (GAA) was found to have the ability to corrode the body surface of the parasite and thus achieve an antiparasitic effect. Next, we evaluated the anthelmintic activity of GAA, the maximum anthelmintic activity of 0.005% GAA for 48 h was 89%, and 0.01% GAA completely killed all Gyrodactylus kobayashii in 40 min. Further research involved evaluating water quality parameters and mRNA expression patterns of xenobiotics sensitive genes, ultimately selecting the treatment method of 0.01% for 40 min followed by transferring the goldfish to normal water for further study. In vitro experiments and scanning electron microscopy results revealed that GAA inhibits parasite activity and ultimately leads to parasite death by disrupting the structure of the parasite's body surface. Overall, these findings suggest that GAA could be a promising alternative compound for controlling Gyrodactylus infections and targeted disruption of the worm's body surface structure is an effective strategy for eliminating the parasite. • Targeted destruction of the epidermis of Gyrodactylus kobayashii is an effective way to screen for drugs. • The use of glacial acetic acid for the control of Gyrodactylus kobayashii is proposed. • 40 mins glacial acetic acid baths at concentrations of 0.01% are effective in the control of Gyrodactylus kobayashii. [ABSTRACT FROM AUTHOR]

Snakehead vesiculovirus (SHVV) is one of the most harmful viral diseases to the snakehead farming industry. Subunit vaccines with highly protective effects strongly depend on the type of vaccine antigen. In order to screen the potential antigen proteins with efficient immunogenicity and reactogenicity, the glycoprotein (G), matrix protein (M), nucleoprotein (N) and phosphoprotein (P) of SHVV were molecular cloned, sequences analyzed and prokaryotic expressed in this study, then four recombinant proteins were served as subunit vaccines to immunize snakehead by intraperitoneal injection to evaluate the immune effects based on the indexes including the serum antibody level, nonspecific enzyme activity, immune-related gene expression and relative percent survivals (RPS). The results showed that compared with control group, the serum antibody levels and T-AOC activities were significantly higher in all four subunit vaccine groups, the serum ACP and AKP activities in four subunit vaccine groups were higher with different degree, and the detected immune-related genes expression levels were remarkably higher in four subunit vaccine groups except IL-8 gene in spleen of rP group. Among four subunit vaccines, rG protein displayed better immune effect than other three proteins. Besides, the RPS of rG group was highest with 83.3%, followed by rM (66.7%), rN (50.0%) and rP (8.3%), respectively. The above results indicated that glycoprotein was a better candidate protective antigen of SHVV and held potential to protect Snakehead from SHVV infection in the type of subunit vaccine. • Four subunit vaccines encoding G, M, N and P proteins of SHVV were constructed. • Four subunit vaccines significantly increased serum specific antibody level. • Four subunit vaccines enhanced the serum enzyme activities and immune-related gene expression with different degree. • The RPS of rG group was highest with 83.3%, followed by rM (66.7%), rN (50.0%) and rP (8.3%), respectively. • Glycoprotein was a better candidate protective antigen and held potential to protect Snakehead from SHVV infection in the type of subunit vaccine. [ABSTRACT FROM AUTHOR]

The largemouth bass virus (LMBV) is a commonly encountered pathogen in aquaculture and presents significant challenges to development of the largemouth bass industry due to the lack of effective treatment methods. Here, the inhibitory potential and underlying mechanisms of adamantoyl chloride (AdCl) against LMBV were assessed both in vitro and in vivo. The results showed that AdCl (IC 50 = 72.35 μM) significantly inhibited replication of LMBV in epithelioma papulosum cyprini (EPC) cells. The results of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide and cytopathic effect (CPE) assays confirmed that AdCl inhibited replication of LMBV in EPC cells and significantly reduced the CPE effect, respectively. As a potential mechanism, AdCl inhibited apoptosis as determined by fluorescence and transmission electron microscopy. The results of flow cytometry showed that the apoptosis rate was decreased by 69 % in the AdCl-treated group as compared to the LMBV-infected group. Additionally, AdCl inhibited viral release. In vivo , the survival rate was 16.2 % higher in the AdCl-treated group as compared to the LMBV-infected group (26.9 % vs. 10.7 %, respectively). Additionally, the results of quantitative reverse transcription polymerase chain reaction (RT-qPCR) showed that AdCl significantly reduced the viral load of the fish liver, spleen, and kidneys at 3, 6, and 9 days postinfection. In addition, RT-qPCR analysis found that AdCl upregulated expression of immune-related genes to suppress replication of LMBV. Collectively, these results confirmed the anti-LMBV activities of AdCl for use in the aquaculture industry. • Adamantoyl chloride significantly improved the survival rate of EPC cells and largemouth bass after LMBV infection. • Adamantoyl chloride can inhibit LMBV induced apoptosis, thereby inhibiting LMBV replication. • Adamantoyl chloride can enhance the immune ability of largemouth bass. [ABSTRACT FROM AUTHOR]

Streptococcal disease is one of the most serious diseases in tilapia, causing huge economic losses to the tilapia farming industry. Streptococcus agalactiae (S. agalactiae) and Streptococcus iniae (S. iniae) are the two main pathogens of tilapia streptococcosis. Vaccination has been proved to be an effective measure to control fish bacterial diseases. In this study, we selected the Enolase (Eno) as the candidate vaccine antigen, which is the common antigen of S. agalactiae and S. iniae with high similarity (97.2%), the rEno was obtained and the CNT-rEno nanocarrier vaccine system was constructed by connecting the rEno protein with functionalized carbon nanotubes (CNTs), the immersion immune effect against S. agalactiae and S. iniae infection was evaluated. The results showed that, compared with the control group, CNT-rEno significantly enhanced the serum antibody production, related enzyme activities and immune-related genes expression. It was worth noting that CNT-rEno demonstrated better immunoprotection against S. agalactiae and S. iniae infection, with relative percent survivals of 73.68% (S. agalactiae) and 68.96% (S. iniae), respectively, which were both much higher than those of rEno groups (36.84% and 31.03%, respectively). Our study indicated that the CNT-rEno nanovaccine had the ability to elicit robust immune responses in tilapia by immersion immunization, and had the potential to offer cross-protection against S. agalactiae and S. iniae infection. • Enolase (Eno) is a common and conserved antigen between S. agalactiae and S. iniae. • CNT-rEno significantly increases the serum specific antibody level and related enzyme activities. • CNT-rEno can regulate immune-related genes expression to enhance immune response. • CNT-rEno provides cross-protection against S. agalactiae and S. iniae infection in tilapia by immersion immunization. [ABSTRACT FROM AUTHOR]

The subheading "Photoemission measurement", now reads: "Spectral response photoemission measurements." Finally, in the Methods, under the subheading 'Sandwiching bialkali antimonide photocathodes between graphene and nickel thin films', "Graphene consisting of mainly monolayer regions with some multiple layer regions was synthesized via chemical vapor deposition (CVD) SP 43 sp on Cu substrates and transferred onto TEM mesh grids using an established polymer-supported method that involves distilled water exposure SP 44 sp . [Extracted from the article]

Gyrodactylosis is a common parasitic disease that affects both farmed and wild fish. Current strategies of chemotherapy are not always satisfactory, requiring the discovery of new anthelmintic agents. Arctigenin is a natural dibenzylbutyrolactone lignin present in several plants with many biological activities. In this study, in vitro and in vivo anthelminthic efficacy of arctigenin against Gyrodactylus kobayashii in goldfish ( Carassius auratus ) is reported for the first time. In in vitro trials, exposure to arctigenin caused rapid declines in motility and ultimate death of worms. A positive correlation was seen between arctigenin concentrations and the time to parasite death, which, at the highest concentration of 8 mg/L occurred at 33 min. Bathing G. kobayashii -infected goldfish in arctigenin significantly reduced infection prevalences and intensities as compared to the control, with EC 50 values of 1.85 and 1.58 mg/L after 24 and 48-h exposure, respectively, with 100% efficacy against G. kobayashii at 4.0 mg/L after only 4 h. Acute toxicity assay indicated that the LC 50 of arctigenin against goldfish after 96-h exposure was 11.63 mg/L, which was 6.29 times higher than the 24 h EC 50 . The expression of four xenobiotic sensitive genes ( cyp1a, hsp70, gst and sod ) were significantly altered in the initial 48 h after arctigenin treatment, but had a tendency of returning to the initial level of gene expression after 96 h. In addition, SEM and TEM were used to study the specific action of arctigenin against gyrodactylids. SEM revealed that arctigenin-mediated worm killing was associated with tegumental damage and with damage seen by TEM to the mitochondria may be a cause of parasite death. Collectively, these findings demonstrate the potential of arctigenin as an alternative natural compound for controlling infections of Gyrodactylus . With further medicinal chemistry optimization, more potent arctigenin analogues offer promise for future combinatorial or replacement anthelmintic control [ABSTRACT FROM AUTHOR]

Ichthyophthirius multifiliis causes high mortality rate of freshwater fish. It is necessary to find the effective alternatives that may both be affordable and environmentally acceptable since malachite green is banned to use. In this work, magnolol exhibited great anti-parasitic activity against all stages of I. multifiliis . Magnolol at concentrations of 0.6 mg/L or more resulted in 100% mortality of I. multifiliis theronts within 4 h exposure; and terminated reproduction of I. multifiliis post 6 h exposure of protomonts and encysted tomonts to 0.8 and 1.0 mg/L, respectively. Moreover, some of tomonts presented morphological characteristic changes and a larger part of tomonts were unable to reproduce. Magnolol possibly had a directly effect on the cell membrane, and more importantly, it could permeate into an encysted tomont across the cyst wall and then impact on the tomont proliferation. In vivo trials showed that 5 h exposure of infected fish to 1.5 mg/L of magnolol significantly reduced the number of theronts released from tomonts. In addition to determination of anti- Ichthyophthirius activity, we also systematically evaluated the safety of magnolol against fish. First of all, the results of acute toxicity experiment showed that the 96 h median lethal concentration (LC 50 ) of magnolol to goldfish was 6.02 mg/L. Furthermore, gene expression ( cyp1a , hsp70 , gst and sod ) and enzyme activity (GSH, SOD and T-AOC) in liver, spleen and kidney could recover to the same level as the control group up to 48 h, though magnolol induced goldfish stress response during 6–24 h exposure. More than that, magnolol can be easily synthesized with low cost, and further embellished and modified for higher bioactivity and lower toxicity because of its simple and symmetry chemical structure. Therefore, magnolol has the potential to be a safe and effective therapeutant, and it also can be used as a probable leading compound for the development of commercial drug to control ichthyophthiriasis in aquaculture. [ABSTRACT FROM AUTHOR]

Micropterus salmoides rhabdovirus (MSRV) is the most lethal viral pathogen in largemouth bass farming, especially threatening the health and survival of bass fry. However, there are still no specific commercialized drugs or vaccines to control MSRV infection. In this study, we identified a red-pigmented bacterial strain from the gut of M. salmoides , Serratia marcescens MS01. Interestingly, we found the methanol extracts of sediment (SED) of S. marcescens MS01 showed highly efficient anti-MSRV activity. SED effectively reduced the virulence of MSRV at a concentration of 30 mg/L, while the inhibition rate of glycoprotein and nucleoprotein expression of MSRV reached 99% in GCO cells. Besides, SED inhibited MSRV-induced oxidative stress and increased the activity of antioxidant enzyme in SOD and CAT. Subsequently, further purification, activity analysis, and multi-spectroscopic identification indicated prodigiosin played a crucial role in inhibiting MSRV in SED. Altogether, our finding suggests that SED or prodigiosin has the potential to be useful as a promising antiviral strategy against MSRV in aquaculture farms. [Display omitted] • S. marcescens extracts (SED) from the intestines of M. salmoides displayed anti-MSRV activity • SED inhibited MSRV-induced oxidative stress. • Prodigiosin played a crucial role of SED in inhibiting MSRV. [ABSTRACT FROM AUTHOR]

The gut microbiota of vertebrates plays a critical role in resistance to invading pathogens. Spring viremia of carp (SVC) is one of the most severe viral diseases in aquaculture. The causative agent is the SVC virus (SVCV), resulting in devastating damage to cyprinid. Yet, knowledge regarding the relationship between the gut microbes and disease is still lacking, particularly the dynamic alteration of the gut microbiota in fish following SVCV infection. To understand the longitudinal effects of SVCV infection on the microbiota of the zebrafish intestine, an intraperitoneal injection zebrafish model mimicking acute SVCV infection in fish with typical virologic and pathologic features was used. Intestinal microbes from both control (CON) and SVCV-infected fish were characterized at various time points by 16S ribosomal RNA gene V3-V4 region sequencing. Viral load in spleen, kidney, and intestine and the total bacterial load in the gut were detected by qPCR. The results showed that SVCV infection was associated with alterations of the gut microbiota in zebrafish as indicated by both alpha and beta diversity indexes. Compared with the CON group, SVCV-infected fish had significantly reduced bacterial diversity at 4 to 6 days post-infection (dpi). It has been found that a number of bacteria were enriched in opportunistic pathogens and depleted of beneficial commensals, at the time of onset of obvious symptoms or even death and at the time of complete disappearance of symptoms. A noticeably higher relative abundance of opportunistic pathogens, such as Clostridium_XlVa , Vibrio , Aeromonas , Mycoplasmataceae_unclassified , and Rothia ; and a lower relative abundance of beneficial symbionts were found in the gut microbiome at 4, 7, 10 days post-infection. Five biomarkers showed high accuracy for distinguishing SVCV-infected fish from CON with an area under the curve (AUC) up to 0.78, 0.80, 0.79, 0.89, and 0.84, respectively. The relative abundance of Enterobacteriaceae_unclassified showed a positive correlation with viral loads of SVCV and the relative abundance of Cetobacterium and Aeromonas were positively related to the bacterial load in the gut, while the same results were observed for the corresponding two phyla (Fusobacteria and Proteobacteria). SVCV causes long-term gut microbiome dysbiosis, which is linked to viral load in target organs and total intestinal bacterial count. The results of our study suggest the potential value of the gut microbiota as a diagnostic biomarker and therapeutic target for SVC, but further validation is required. • SVCV-infected fish had significantly reduced gut bacterial diversity at 4 to 6 dpi. • The richness and composition of the intestinal microbiota were dynamically changing after SVCV infection. • Several bacteria were enriched in opportunistic pathogens and depleted of beneficial commensals. • Five biomarkers (Clostridium_XlVa, Vibrio, Aeromonas, Mycoplasmataceae_unclassified, and Rothia) were identified. • SVCV causes gut microbiome dysbiosis, which is linked to viral load in target organs and total intestinal bacterial count. [ABSTRACT FROM AUTHOR]

Largemouth bass (Micropterus salmoides), one of the most important freshwater commercial fish species has been widely cultivated in China. In recent years, the nocardiosis caused by Nocardia seriolae has greatly damaged the M. salmoides industry and there is no effective treatment at present. Currently, Cetobacterium somerae , the predominant bacteria in the gut of many freshwater fishes has been reported to be associated with fish health. However, whether the native C. somerae could protect the host from N. seriolae is unclear. In this study, M. salmoides were fed with three different diets, including control diet (CD), low C. somerae diet (106 CFU/g as LD) and high C. somerae diet (108 CFU/g as HD). After 8-week feeding, growth performance, gut health index, serum enzyme activities and the expression of inflammation-related genes were tested. Results showed that the LD and HD diets had no adverse effects on the growth performance. Moreover, dietary HD enhanced gut barrier and reduced intestinal ROS and ORP, as well as increased serum enzyme activities including ACP, AKP, SOD and LZM compared to the CD group. In addition, the HD diet significantly up-regulated the expression of TNF-α , IL8 , IL-1β and IL15 , while down-regulating the expression of TGF-β1 and IL10 in kidney. Moreover, the expression of antibacterial genes was significantly increased in HD group after being challenged by N. seriolae. And the fish fed HD diet exhibited higher survival rate (57.5%) than that in CD (37.5%) and LD groups (42.5%). To summarize, our study demonstrates that dietary HD can enhance gut health, improve immune response and strengthen pathogen resistance, suggesting that C. somerae is a potential probiotic for defending against N. seriolae infection in M. salmoides. • The indigenous Cetobacterium somerae strain was applied as dietary probiotics for largemouth bass. • Dietary C. somerae improved the gut health and immune response of largemouth bass. • Dietary C. somerae reduced the mortality of largemouth bass infected by N. seriolae. [ABSTRACT FROM AUTHOR]