The Fish Microbiota:Research Progress and Potential Applications

The gut microbiota plays an important role in host health and disease.Our understanding of the fish microbiota lags far behind our knowledge of that of humans and other mammals.Nevertheless,research has highlighted the importance of the microbiota in the health,performance,and various physiological functions of fish.The microbiota has been studied in various fish species,including model animals,economic fish,and wild fish species.The composition of the fish microbiota depends on host selection,diet,and environmental factors.The intestinal microbiota affects the nutritional metabolism,immunity,and disease resistance of the fish host,while the host regulates the intestinal microbiota in a reciprocal way through both immune and non-immune factors.Improved and novel gnotobiotic fish models have been developed,which are important for the mechanistic study of host–microbiota interactions in fish.In this review,we discuss recent progress in fish microbiota research.We describe various aspects of this research,including both studies on fish microbiota variations and fundamental research extending our knowledge of host–microbiota interaction in fish.Perspectives on how fish microbiota research may benefit fish health and industrial sustainability are also discussed.

An Improved Multi-Objective Hybrid Genetic-Simulated Annealing Algorithm for AGV Scheduling under Composite Operation Mode

This paper presents an improved hybrid algorithm and a multi-objective model to tackle the scheduling problem of multiple Automated Guided Vehicles(AGVs)under the composite operation mode.The multi-objective model aims to minimize the maximum completion time,the total distance covered by AGVs,and the distance traveled while empty-loaded.The improved hybrid algorithm combines the improved genetic algorithm(GA)and the simulated annealing algorithm(SA)to strengthen the local search ability of the algorithm and improve the stability of the calculation results.Based on the characteristics of the composite operation mode,the authors introduce the combined coding and parallel decoding mode and calculate the fitness function with the grey entropy parallel analysis method to solve the multi-objective problem.The grey entropy parallel analysis method is a combination of the grey correlation analysis method and the entropy weighting method to solve multi-objective solving problems.A task advance evaluation strategy is proposed in the process of crossover and mutation operator to guide the direction of crossover and mutation.The computational experiments results show that the improved hybrid algorithm is better than the GA and the genetic algorithm with task advance evaluation strategy(AEGA)in terms of convergence speed and solution results,and the effectiveness of the multi-objective solution is proved.All three objectives are optimized and the proposed algorithm has an optimization of 7.6%respectively compared with the GA and 3.4%compared with the AEGA in terms of the objective of maximum completion time.

Reinforcement⁃Learning⁃Based Appointed⁃Time Prescribed Performance Attitude Control for Rigid Spacecraft

This paper addresses a geometric control algorithm for the attitude tracking problem of the rigid spacecraft modeled on SO(3).Considering the topological and geometric properties of SO(3),we introduced a smooth positive attitude error function to convert the attitude tracking issue on SO(3)into the stabilization counterpart on its Lie algebra.The error transformation technique was further utilized to ensure the assigned transient and steady state performance of the attitude tracking error with the aid of a well⁃designed assigned⁃time performance function.Then,using the actor⁃critic(AC)neural architecture,an adaptive reinforcement learning approximator was constructed,in which the actor neural network(NN)was utilized to approximate the unknown nonlinearity online.A critic function was introduced to tune the next phase of the actor neural network operation for performance improvement via supervising the system performance.A rigorous stability analysis was presented to show that the assigned system performance can be achieved.Finally,the effectiveness and feasibility of the constructed control strategy was verified by the numerical simulation.

Regional Renewable Energy Optimization Based on Economic Benefits and Carbon Emissions

With increasing renewable energy utilization,the industry needs an accurate tool to select and size renewable energy equipment and evaluate the corresponding renewable energy plans.This study aims to bring new insights into sustainable and energy-efficient urban planning by developing a practical method for optimizing the production of renewable energy and carbon emission in urban areas.First,we provide a detailed formulation to calculate the renewable energy demand based on total energy demand.Second,we construct a dual-objective optimization model that represents the life cycle cost and carbon emission of renewable energy systems,after which we apply the differential evolution algorithmto solve the optimization result.Finally,we conduct a case study in Qingdao,China,to demonstrate the effectiveness of this optimizationmodel.Compared to the baseline design,the proposedmodel reduced annual costs and annual carbon emissions by 14.39%and 72.65%,respectively.These results revealed that dual-objective optimization is an effective method to optimize economic benefits and reduce carbon emissions.Overall,this study will assist energy planners in evaluating the impacts of urban renewable energy projects on the economy and carbon emissions during the planning stage.

Wendan decoction improves learning and memory deficits in a rat model of schizophrenia

An experimental model of schizophrenia was established using dizocilpine （MK-801）. Rats were intragastrically administered with Wendan decoction or clozapine for 21 days prior to establishing the model. The results revealed that the latency of schizophrenia model rats to escape from the hidden platform in the Morris water maze was significantly shortened after administration of Wendan decoction or clozapine. In addition, the treated rats crossed the platform significantly more times than the untreated model rats. Moreover, the rate of successful long-term potentiation induction in the Wendan decoction group and clozapine group were also obviously increased compared with the model group, and the population spike peak latency was significantly shortened. These experimental findings suggest that Wendan decoction can improve the learning and memory ability of schizophrenic rats to the same extent as clozapine treatment.

Chromosomal mapping of 5S and 18S-5.8S-25S rRNA genes in Saccharina japonica(Phaeophyceae)as visualized by dual-color fluorescence in situ hybridization

It has been reported that there was a linkage of 5S rRNA gene to 18S-5.8S-25S rRNA gene in a few of species in Ochrophyta.In regard to the usual two positions of linked 5S rDNA to the 3′end of 25S rDNA,two pairs of primers were designed for amplification to verify this linkage of two genes in a kelp cultivar of Saccharina japonica,one of species in Ochrophyta.This result supplemented the previous report that 5S rDNA was unlinked to 25S rDNA in this kelp.In order to simultaneously visualize this unlinkage of two genes,dual-color fluorescence in situ hybridization(FISH)technique was applied to the cytogenetics of S.japonica.Dual-color FISH images showed that two and four hybridization signals were present in the kelp gametophyte and sporophyte,respectively,metaphase nuclei hybridized simultaneously with the labeled probes of 18S rDNA and 5S rDNA.Both haploid and diploid karyotypes in decreasing length of chromosomes showed that 18S-5.8S-25S rDNA was localized at the interstitial region of Chromosome 23,whereas 5S rDNA resided at the sub-telomeric region of Chromosome 27.These karyotypes suggested that the kelp nuclear genome had only one locus of each rRNA gene,and their loci on different chromosomes indicated the physical unlinkage of 5S rDNA to 18S-5.8S-25S rDNA in this kelp.Therefore,dual-color FISH seems to be a powerful technique for the discrimination and pairing of chromosomes featured in both small size and nearly identical shape in S.japonica.

Preparation,Characterization and Applications of Titanate/Titania Nanocrystals

The present paper focused on the preparation of hydrogen titanate nanotubes and nanowires and their conversion into titania by heat treatments.The structural,morphology and optical properties of as-prepared nanostructured titanate and titania were investigated by transmission electron microscopy (TEM),X-ray diffraction (XRD) and diffusive reflectance spectra.The slim diameter of these nanostructured titanate and titania,the versatile crystal structure and special optical and electronic properties may make them find versatile applications in chemical sensors for multiple purposes.

Highly Active Rutile TiO_2 for Photocatalysis

Nanocrystalline titania was prepared by the homogeneous-precipitation method at temperature lower than 120℃. The properties of powders were identified by XRD,TEM and diffuse reflection spectra.The results showed that rutile titania formed at 70℃without calcination in air.Nanometer rutile TiO_2 had good crystalline and small particle size.The formation mechanism of rutile was also discussed.The photocatalytic activity of the prepared particles was tested for the degradation of methyl orange.The photocatalytic activity of rutile TiO_2 was higher than those obtained from Degussa P-25 TiO_2.The reasons for high photocatalytic activity of futile were discussed.

Fabrication and Characterization of GCO Electrolyte Films

Gd-doped Ceria (GCO:Gd_(0.1)Ce_(0.9)O_(1.95)) sensing films have been fabricated successfully on glasses and porous Al_2O_3 ceramic substrates by RF magnetron sputtering.Sputtering conditions such as power and temperature have been investigated and the sample was characterized in detail by XRD,SEM and AC impedance spectroscopy.The results show that the films grow preferentially along the (111) compact plane with a pure fluorite structure and the crystal grain grows more sufficiently with increasing of the annealing temperature.In addition,a high oxygen ion conductivity of 2.24×10^(-2) S.cm^(-1) is achieved at 800℃.

Robust Near-Hovering Flight Controller for Model-Scale Helicopters Via Parametric Approach

This paper aims to provide a parametric design for robust flight controller of the model-scale helicopter. The main contributions lie in two aspects. Firstly,under near-hovering condition,a procedure is presented for simplification of the highly nonlinear and under-actuated model of the model-scale helicopter. This nonlinear system is linearized around the trim values of the chosen flight mode,followed by decomposing this high-order linear model into three lower-order subsystems according to the coupling properties among channels.After decomposition,the three subsystems are obtained which include the coupling subsystem between the roll( pitch) motion and the lateral( longitudinal) motion,the subsystem of the yaw motion and the subsystem of the vertical motion. Secondly,by using eigenstructure assignment,the problem of flight controller design can be converted into solving two optimization problems and the linear robust controllers of these subsystems are designed through solving these optimization problems. Besides, this paper contrasts and analyzed the performances of the LQR controller and the parametric controller. The results demonstrate the effectiveness and the robustness against the parametric perturbations of the parametric controller.

The direct and gut microbiota-mediated effects of dietary bile acids on the improvement of gut barriers in largemouth bass(Micropterus salmoides)

Fish gut barrier damage under intensive culture model is a significant concern for aquaculture industry.This study aimed to investigate the effects of bile acids(BAs)on gut barriers in Micropterus salmoides.A germ-free(GF)zebrafish model was employed to elucidate the effects of the direct stimulation of BAs and the indirect regulations mediated by the gut microbiota on gut barrier functions.Four diets were formulated with BAs supplemented at 0,150,300 and 450 mg/kg,and these 4 diets were defined as control,BA150,BA300 and BA450,respectively.After 5 weeks of feeding experiment,the survival rate of fish fed with BA300 diet was increased(P<0.05).Histological analysis revealed an improvement of gut structural integrity in the BA150 and BA300 groups.Compared with the control group,the expression of genes related to chemical barrier(mucin,lysozyme and complement 1)and physical barrier(occludin and claudin-4)was increased in the BA150 and BA300 groups(P<0.05),and the expression of genes related to immunological barrier(interleukin[IL]-6,tumor growth factorβ,IL-10,macrophage galactosetype lectin and immunoglobulin M[Ig M])was significantly increased in the BA300 group(P<0.05),but the expression of genes related to chemical barrier(hepcidin)and immunological barrier(IL-1β,tumor necrosis factor-a,IL-6 and arginase)was significantly decreased in the BA450 group(P<0.05).Gut microbiota composition analysis revealed that the abundance of Firmicutes was augmented prominently in the BA150 and BA300 groups(P<0.05),while that of Actinobacteriota and Proteobacteria showed a downward trend in the BA150 and BA300 groups(P>0.05).The results of the gut microbiota transferring experiment demonstrated an upregulation of gut barrier-related genes,including immunoglobulin Z/T(Ig Z/T),IL-6,IL-1βand IL-10,by the gut microbiota transferred from the BA300 group compared with the control(P<0.05).Feeding the BA300 diet directly to GF zebrafish resulted in enhanced expression of Ig M,Ig Z/T,lysozyme,occludin-2,IL-6 and IL-10(P<0.05).In conclusion,BAs can improve the gut barriers of fish through both direct and indirect effects mediated by the gut microbiota.

Molecular and FISH analysis of 45S rDNA on BAC molecule of Saccharina japonica

IGS is abundant in polymorphism,which is widely used in the analysis of intraspecific genetic diversity and phylogenetic relationships among geographical populations.In this study,the 45S rDNA repeat unit of Saccharina japonica was obtained for the first time by BAC clone sequencing.The total length of the 45S rDNA repeat unit of S.japonica was 8995 bp,including 5420 bp of 18S-5.8S-25S rDNA,and 3575 bp of IGS(Intergenic Spacer),with the GC content of 51.4%.The IGS was composed of a 465 bp of 3′-outer transcribed spacer(ETS),an 874 bp 5′-ETS,and a 2236 bp non-transcribed spacer(NTS),with the GC content of 50.1%.Fiber-FISH(fiber-fluorescence in situ hybridization)analysis of the distribution of 45S rDNA repeat units on the bacterial artificial chromosome illustrated that each fiber had at least five continuously moniliform hybridization signal points.This study provided a new candidate molecular marker for detecting intraspecific polymorphisms of S.japonica.In addition,the successful fiber-FISH analysis of the 45S rDNA on BAC molecule would contribute to the construction of the physical map and map-based cloning of this kelp.

Research advances in the structure,function,and regulation of the gill barrier in

The gill is an important organ in fish that is involved in various physiological functions,including respiration,filter-feeding,ammonia nitrogen excretion,and osmoregulation.The physiological functions of gills are closely related to their structure,external feeding conditions,and environmental factors.Herein,we first briefly summarize the basic structure and functions of the gills of teleosts,then explain the structure and function of the gill barrier(as a microbial barrier,a chemical barrier,a physical barrier,and an immune barrier)in detail.Finally,we introduce the regulation of fish gill barrier health by ubiquitous feeding factors and environmental factors,and provide an outlook on the prospects of gill barrier health.We found that improving health through modulating feed factors is more convenient than improving environmental factors.This review increases our understanding of how nutrient composition and level in fish diet influences gill health and overall growth performance of fish.

OsMADS16 Genetically Interacts with OsMADS3 and OsMADS58 in Specifying Floral Patterning ~in Rice

Rice （Oryza sativa） has unique floral patterns that contribute to grain yield. However, the molecular mechanism underlying the specification of floral organ identities in rice, particularly the interaction among floral homeotic genes, remains poorly understood. Here, we show that the floral homeotic gene OsMADS16 （also called SUPERWOMAN1, SPWl, a B-class gene） acts together with the rice C-class genes OsMADS3 and OsMADS58 in specifying floral organ patterning. OsMADS16 and the two C-class genes have an overlapping expression pattern in the third whorl founder cells. Compared with the single mutants, both spwl-1 osmads3-4 and spwl-1 osmads58 double mutants exhibit additional whorls of glume-like organs within the flower, particularly an extra whorl of six glume-like structures formed at the position of the wild-type stamens. These ectopic glume-like structures were shown to have palea identity through cellular observation and in situ hybridization analysis using marker genes. Our results suggest that B- and C-class genes play a key role in suppressing indeterminate growth within the floral meristem, particularly whorl-3 primordia. We also hypothesize that, in contrast to previous assumptions, the specialized spikelet organ in rice, the palea, is the counterpart of the sepal in eudicots, and the lemma is homologous to the bract.

Antibiotic growth promoter olaquindox increases pathogen susceptibility in fish by inducing gut microbiota dysbiosis

Low dose antibiotics have been used as growth promoters in livestock and fish. The use of antibiotics has been associated with reduced pathogen infections in livestock. In contrast, antibiotic growth promoter has been suspected of leading to disease outbreaks in aquaculture. However, this phenomenon is circumstantial and has not been confirmed in experimental conditions. In this study,we showed that antibiotic olaquindox increased the susceptibility of zebrafish to A. hydrophila infection. Olaquindox led to profound alterations in the intestinal microbiota of zebrafish, with a drastic bloom of Enterobacter and diminishing of Cetobacterium. Moreover, the innate immune responses of zebrafish were compromised by olaquindox(P<0.05). Transfer of microbiota to GF zebrafish indicated that while the immuo-suppression effect of olaquindox is a combined effect mediated by both OLA-altered micro biota and direct action of the antibiotic(P<0.05), the increased pathogen susceptibility was driven by the OLA-altered microbiota and was not dependent on direct antibiotic effect. Taken together, these data indicate that low level of OLA induced gut microbiota dysbiosis in zebrafish, which led to increased pathogen susceptibility.

Effects of dietary yeast nucleotides on growth, non-specific immunity intestine growth and intestinal microbiota of juvenile hybrid tilapia Oreochromis niloticus ♀ × Oreochromis aureus ♂

This study investigated the effect of dietary supplementation of yeast nucleotides on the growth, nonspecific immunity, intestine growth and intestinal microbiota of juvenile hybrid tilapia. Tilapia(initial average weight of 8.02 g) was fed test diets supplemented with a yeast-originated nucleotide mixture(0,0.15, 0.30, 0.60, and 1.20 g/100 g diet) for 8 weeks. Fish fed the diet with 0.60% nucleotide had significantly higher weight gain than the control group(P < 0.05). Feed efficiency was improved in the fish fed 0.60 and 1.20% nucleotide compared with that in the control group. The optimal doses of nucleotides supplementation for growth and feed efficiency of fish were determined as 0.63 and 0.81%, respectively.Intestinal growth was improved in the 0.30 and 0.60% groups, as indicated by significant increase in intestine length. The fish fed 0.60 and 1.20% nucleotide showed higher super oxide dismutase(SOD)activity and lower malondialdehyde(MDA) level in the liver than the control fish, indicating enhancement of the anti-oxidant status. Serum lysozyme activity was significantly increased in the 0.15 and 0.3%nucleotide supplementation groups, suggesting an enhancement effect on the non-specific immune response. Lastly, dietary nucleotides supplementation exerted moderate influence on the intestinal microbiota of hybrid tilapia. A reduction in the cumulative abundance of putative butyrate-producing species was observed in the intestinal microbiota of fish fed diets with 0.60% nucleotide compared with the control, implying an interaction between dietary nucleotides and butyrate production. Briefly, dietary supplementation with 0.60% nucleotide improve the growth performance, immune activity and intestine growth in tilapia.

Interactions between commensal bacteria and viral infection:insights for viral disease control in farmed animals

Viral diseases cause serious economic loss in farmed animals industry.However,the efficacy of remedies for viral infection in farmed animals is limited,and treatment strategies are generally lacking for aquatic animals.Interactions of commensal microbiota and viral infection have been studied in recent years,demonstrating a third player in the interaction between hosts and viruses.Here,we discuss recent developments in the research of interactions between commensal bacteria and viral infection,including both promotion and inhibition effect of commensal bacteria on viral pathogenesis,as well as the impact of viral infection on commensal microbiota.The antiviral effect of commensal bacteria is mostly achieved through priming or regulation of the host immune responses,involving differential microbial components and host signaling pathways,and gives rise to various antiviral probiotics.Moreover,we summarize studies related to the interaction between commensal bacteria and viral infection in farmed animals,including pigs,chickens,fish and invertebrate species.Further studies in this area will deepen our understanding of antiviral immunity of farmed animals in the context of commensal microbiota,and promote the development of novel strategies for treatment of viral diseases in farmed animals.

Full-length mRNA sequencing in Saccharina japonica and identification of carbonic anhydrase genes

The carbonic anhydrases(CAs)are a group of enzymes that play an important role in the absorption and transportation of CO_(2) in Saccharina japonica.They are encoded by a superfamily of genes with seven subtypes that are unrelated in sequence but share conserved function in catalyzing the reversible conversion of CO_(2) and HCO_(3)^(-).Here we have characterized the CA members in the transcriptome of S.japonica using Single-molecule real-time(SMRT)sequencing technology.Approximately 9830.4 megabases from 5,028,003 quality subreads were generated,and they were assembled into 326,512 full-length non-chimeric(FLNC)reads,with an average flnc read length of 2181 bp.After removing redundant sequences,79,010 unique transcripts were obtained of which 38,039 transcripts were successfully annotated.From the full-length transcriptome,we have identified 7 full-length cDNA sequences for CA genes(4α-CAs,1β-CAs and 2γ-CAs)and assessed for their potential functions based on phylogenetic analysis.Characterizations of CAs will provide the ground for future studies to determine the involvement of CAs in inorganic carbon absorption and transportation in S.japonica.

Risk factors and a prediction model for sepsis: A multicenter retrospective study in China

Background:Sepsis is typically associated with poor outcomes.There are various risk factors and predictive mod-els for sepsis based on clinical indicators.However,these models are usually predictive of all critical patients.This study explored the risk factors for 28-day outcomes of patients with sepsis and developed a prognosis prediction model.Methods:This was a multicenter retrospective analysis of sepsis patients hospitalized in three intensive care units(ICUs)from September 1st 2015,to June 30th 2020.Demographic,clinical history,and laboratory test data were extracted from patient records.Investigators explored the risk factors affecting 28-day sepsis prognosis by univariate analysis.The effects of confounding factors were excluded by multivariate logistic regression analysis,and new joint predictive factors were calculated.A model predicting 28-day sepsis prognosis was constructed through data processing analysis.Results:A total of 545 patients with sepsis were included.The 28-day mortality rate was 32.3%.Risk factors including age,D-dimer,albumin,creatinine,and prothrombin time(PT)were predictive of death from sepsis.The goodness-of-fit value for this prediction model was 0.534,and the area under the receiver operating characteristic curve was 0.7207.Further analysis of the immune subgroups(n=140)revealed a significant decrease in CD3+,CD4+CD8-,and CD4+CD29+memory effector T lymphocytes and an increase in CD56+natural killer(NK)cells in the hypoalbuminemia group compared with the normal albumin group(65.5 vs.58.3,P=0.005;41.2 vs.32.4,P=0.005;21.8 vs.17.1,P=0.029;12.6 vs.17.6,P=0.004).Conclusions:Risk factors for 28-day sepsis mortality include age,D-dimer,creatinine,PT,and albumin.A decrease in albumin level may exacerbate immunosuppression in patients with sepsis.This study establishes a prediction model based on these indicators,which shows a good degree of calibration and differentiation.This model may provide good predictive value for clinical sepsis prognosis.