Dynamic Analysis of a Predator-Prey Model with Holling-II Functional Response

A predator-prey model with linear capture term Holling-II functional response was studied by using differential equation theory. The existence and the stabilities of non-negative equilibrium points of the model were discussed. The results show that under certain limited conditions, these two groups can maintain a balanced position, which provides a theoretical reference for relevant departments to make decisions on ecological protection.

碳纤维增强共聚酰胺6-66复合材料的制备及性能

通过两段式聚合法制备共聚酰胺PA6-66,然后采用熔融共混得到碳纤维增强PA6-66复合材料(CF/PA6-66)。对复合材料的断面形貌、热性能、结晶性能、非等温结晶动力学、熔体流变性、力学性能和动态力学性能进行了分析。差示扫描量热(DSC)和热重分析结果表明,CF/PA6-66复合材料的熔点约为190℃,分解温度在376℃以上。DSC和X射线衍射分析表明,CF的加入加快了聚合物的结晶速率,促进γ晶型的形成。力学性能和熔体流变性能测试结果表明,随着CF含量的增加,复合材料的拉伸强度、弯曲强度与缺口冲击强度均先升高后降低,当CF含量为20%时,CF/PA6-66复合材料的拉伸强度与弯曲强度分别为95.54 MPa和121.42 MPa,相比纯PA6-66分别提升了82.26%和81.17%,同时其黏流活化能仅为35.43 kJ/mol。

Tauroursodeoxycholic acid(TUDCA)improves intestinal barrier function associated with TGR5-MLCK pathway and the alteration of serum metabolites and gut bacteria in weaned piglets

Background:Tauroursodeoxycholic acid(TUDCA),a hydrophilic bile acid,is the main medicinal component of bear bile and is commonly used to treat a variety of hepatobiliary diseases.Meanwhile,TUDCA has been shown to modulate the intestinal barrier function and alleviate DSS-induced colitis in mice.However,the effect of TUDCA on the intestinal barrier of weaned piglets remains largely unclear.Methods:The weaned piglets and porcine IPEC-J2 intestinal epithelial cells were used to investigate the effects of TUDCA on intestinal barrier function in weaned piglets and explore the possible underlying mechanisms.In vivo,72 healthy weaned piglets were randomly allocated into 2 groups according to their gender and body weight,and piglets were fed the basal diet with 0(control,CON)and 200 mg/kg TUDCA for 30 d,respectively.Three female and three male piglets reflecting the average bodyweight were slaughtered in each group and samples were collected.In vitro,IPEC-J2 cells were subjected to 100μmol/L TUDCA to explore the possible underlying mechanisms.Results:Our results demonstrated that dietary TUDCA supplementation significantly reduced the diarrhea incidence of weaned piglets,possibly attributing to the TUDCA-enhanced intestinal barrier function and immunity.In addition,TUDCA supplementation altered serum metabolites and the relative abundance of certain gut bacteria,which might contribute to the improved intestinal barrier function.Furthermore,the in-vitro results showed that TUDCA improved the E.coli-induced epithelial barrier impairment of IPEC-J2 cells and increased Takeda G-coupled protein receptor 5(TGR5)protein expression.However,knockdown of TGR5 and inhibition of myosin light chain kinase(MLCK)pathway abolished the TUDCA-improved epithelial barrier impairment in E.coli-treated IPEC-J2 cells,indicating the involvement of TGR5-MLCK in this process.Conclusions:These findings showed that TUDCA improved intestinal barrier function associated with TGR5-MLCK pathway and the alteration of serum metabolites and gut bacteria in weaned piglets,suggesting the potential application of TUDCA in improving gut health in piglet production.

Genome sequence and evolution of Betula platyphylla

Betula L.(birch)is a pioneer hardwood tree species with ecological,economic,and evolutionary importance in the Northern Hemisphere.We sequenced the Betula platyphylla genome and assembled the sequences into 14 chromosomes.The Betula genome lacks evidence of recent whole-genome duplication and has the same paleoploidy level as Vitis vinifera and Prunus mume.Phylogenetic analysis of lignin pathway genes coupled with tissue-specific expression patterns provided clues for understanding the formation of higher ratios of syringyl to guaiacyl lignin observed in Betula species.Our transcriptome analysis of leaf tissues under a time-series cold stress experiment revealed the presence of the MEKK1–MKK2–MPK4 cascade and six additional mitogen-activated protein kinases that can be linked to a gene regulatory network involving many transcription factors and cold tolerance genes.Our genomic and transcriptome analyses provide insight into the structures,features,and evolution of the B.platyphylla genome.The chromosome-level genome and gene resources of B.platyphylla obtained in this study will facilitate the identification of important and essential genes governing important traits of trees and genetic improvement of B.platyphylla.

Effects of “Bioactive” amino acids leucine, glutamate, arginine and tryptophan on feed intake and mRNA expression of relative neuropeptides in broiler chicks

Feed intake control is vital to ensuring optimal nutrition and achieving full potential for growth and development in poultry. The aim of the present study was to investigate the effects of L-leucine, L-glutamate, L-tryptophan and L-arginine on feed intake and the mRNA expression levels of hypothalamic Neuropeptide involved in feed intake regulation in broiler chicks. Leucine, glutamate, tryptophan or arginine was intra-cerebroventricularly （ICV） administrated to 4d-old broiler chicks respectively and the feed intake were recorded at various time points. Quantitative PCR was performed to determine the hypothalamic mRNA expression levels of Neuropeptide Y （NPY）, agouti related protein （AgRP）, pro-opiomelanocortin （POMC）, melanocortin receptor 4 （MC4R） and corticotrophin releasing factor （CRF）. Our results showed that ICV administration of L-leucine （0.15 or 1.5 μmol） significantly （P〈0.05） increased feed intake up to 2 h post-administration period and elevated both hypothalamic NPY and AgRP mRNA expression levels. In contrast, ICV administration of L-glutamate （1.6 μmol） significantly （P 〈 0.05） decreased feed intake 0.25, 0.5 and 2 h post-injection, and increased hypothalamic CRF and MC4R mRNA expression levels. Meanwhile, both L-tryptophan （10 or 100 μg） and L-arginine （20 or 200 μg） had no significant effect on feed intake. These findings suggested that L-leucine and L-glutamate could act within the hypothalamus to influence food intake, and that both orexigenic and anorexigenic Neuropeptide genes might contribute directly to these effects.

Effects of coagulation-bath conditions on polyphenylsulfone ultrafiltration membranes

Polyphenylsulfone(PPSU)ultrafiltration membrane with different structures was prepared by nonsolvent-induced phase separation.The effects of coagulation bath conditions(concentration and temperature)on membrane morphology,pure water flux,pore size,porosity,and contact angle were studied and discussed based on ternary-phase diagrams.Results indicated that water had stronger coagulant power than ethanol,and that the morphology of the membrane prepared from the polyphenylsulfone/1-methyl-2-pyrrolidinone/H_(2)O(PPSU/NMP/H_(2)O)system had finger-like structures.Conversely,sponge-like structures were observed for the PPSU/NMP/(NMP-H_(2)O)and PPSU/NMP/(70 NMP-EtOH-H_(2)O)systems.Ethanol also greatly influenced on membrane structures.According to the Scanning electronic microscopy(SEM)image,the composition(mass fraction)of casting solution is 16%PPSU-84%NMP and the coagulation bath consisting of 70%NMP-26%H_(2)O-4%C_(2)H_(5)OH.Meanwhile,the PPSU ultrafiltration membrane with spong-like was prepared under 8℃coagulation bath.The formation of sponge-like structure reduces the pure water flux of ppsu membrane from 488.39 L·m^(-2)·h^(-1)to 36.04 L·m^(-2)·h^(-1).It also reduces the gas permeability,porosity,and pore size of the membrane.The addition of ethanol and NMP into the coagulation bath increases the roughness of the PPSU ultrafiltration membrane and reduces the hydrophilicity of the membrane.

Effect of diacylglycerol acyltransferase 2overexpression in 3T3-L1 is associated to an increase in mono-unsaturated fatty acid accumulation

Background：Fatty acid（FA） composition is the most important parameter affecting the flavor and nutritional value of the meat.The final and the only committed step in the biosynthesis of triglycerides is catalyzed by diacylglycerol acyltransferase 2（DGAT2）.The role of DGAT2 in lipid accumulation has been demonstrated in adipocytes,However,little is known about the effect of DGAT2 on the FA composition of these cells.Methods：To investigate the role of DGAT2 in regulating lipid accumulation,FA composition and the expression of adipogenic genes,we cloned the open reading frame of the porcine DGAT2 gene and established 3T3-L1 cells that overexpressed DGAT2.Cells were then cultured in differentiation medium（DM） without FA,with a mixture of FAs（FA-DM）,or containing a ^（13）C stable isotope-labeled FA mixture（IFA-DM）.The FA composition of adipocytes was analyzed by gas chromatography-mass spectrometry and gas chromatography-isotope ratio mass spectrometry.Quantitative PCR and western blotting were employed to detect expression of adipogenic genes in 3T3-L1 adipocytes cultured with FA-DM for 12 d.Results：The triacylglyceride（TAG） content was significantly higher in 3T3-L1 adipocytes overexpressing DGAT2 than in control cells.When cultured in DM or FA-DM for 12 d,cells overexpressing DGAT2 showed a higher proportion of unsaturated FAs（C16：1 and C18：1）.However,when cells overexpressing DGAT2 were cultured with FA-DM for30 min,the FA composition was almost identical to that of controls.Further,the proportion of stable isotope-labeled FAs were similar in 3T3-L1 adipocytes overexpressing DGAT2 and control cells cultured in IFA-DM for 12 d.These results collectively indicate that the higher proportion of mono-unsaturated FAs,C16：1 and C18：1,may originate from de novo FA synthesis but not from the uptake of specific FAs from the medium.This hypothesis is further supported by evidence that both mRNA and protein expression of genes involved in FA synthesis（ACACA,FASN,SCD1,and A-FABP）were significantly higher in cells overexpressing DGAT2 than in control cells.Conclusions：In conclusion,our study revealed that TAG accumulation,the proportion of MUFAs,and the expression of adipogenic genes were higher in 3T3-L1 cells overexpressing DGAT2 than in control cells.

Weis-Fogh Mechanism Mathematic Model of Wave Power Generation Device

A Weis-Fogh mechanism wave power generation system is designed, its physical model and mathematical model are discussed, and the component expressions of fluid dynamic expression are derived. Adopting numerical integral algorithm, the work done by fluid force acting on wing is calculated.

Study on crystallization behavior of Tibet butter

Tibetan butter(TB),generally called butter,is a solid oil product extracted from yak milk in the QinghaiTibet plateau area.However,due to the limitations of raw material sources and production technology,there is a shortage of TB,so it is important to find substitutes of TB.This paper studied the crystallization behavior of six kinds of commercial TB products in Tibet to provide the theoretical basis for the development of TB substitutes for the production of TB lamps and flowers.This study assessed the crystallization behaviors of the TB samples,including isothermal crystallization process and non-isothermal crystallization process.The microstructure,isothermal crystallization of TB were evaluated by polarized light microscopy and low-pulse NMR spectrometry,respectively.The non-isothermal crystallization process of TB under temperature scanning were investigated using Rheometer,and the crystallization behavior under different cooling rates were determined by diferential scanning calorimetry(DSC)procedures.The results showed that the TB was crystallized at a higher supercooling(-10,0 and 10℃).Dimensional growth is dominant;at 20℃,spiral growth dominates.The TB has complex crystallization nucleation behavior.The crystal types of TB are mainlyβ’-crystal form andβ’-like crystal form.The lower the cooling rate,the shorter the crystallization induction time,and the more the number of crystal nuclei.Therefore,during producing TB substitutes in the factory,the cooling rate can be controlled at10℃/min to reduce energy consumption and production costs.

Pindel-TD:A Tandem Duplication Detector Based on A Pattern Growth Approach

Tandem duplication(TD)is a major type of structural variations(SVs)that plays an important role in novel gene formation and human diseases.However,TDs are often missed or incorrectly classified as insertions by most modern SV detection methods due to the lack of specialized operation on TD-related mutational signals.Herein,we developed a TD detection module for the Pindel tool,referred to as Pindel-TD,based on a TD-specific pattern growth approach.Pindel-TD is capable of detecting TDs with a wide size range at single nucleotide resolution.Using simulated and real read data from HG002,we demonstrated that Pindel-TD outperforms other leading methods in terms of precision,recall,F1-score,and robustness.Furthermore,by applying Pindel-TD to data generated from the K562 cancer cell line,we identified a TD located at the seventh exon of SAGE1,providing an explanation for its high expression.Pindel-TD is available for non-commercial use at https://github.com/xjtu-omics/pindel.

High-quality Arabidopsis thaliana Genome Assembly with Nanopore and HiFi Long Reads

Arabidopsis thaliana is an important and long-established model species for plant molecular biology,genetics,epigenetics,and genomics.However,the latest version of reference genome still contains a significant number of missing segments.Here,we reported a high-quality and almost complete Col-0 genome assembly with two gaps(named Col-XJTU)by combining the Oxford Nanopore Technologies ultra-long reads,Pacific Biosciences high-fidelity long reads,and Hi-C data.The total genome assembly size is 133,725,193 bp,introducing 14.6 Mb of novel sequences compared to the TAIR10.1 reference genome.All five chromosomes of the Col-XJTU assembly are highly accurate with consensus quality(QV)scores>60(ranging from 62 to 68),which are higher than those of the TAIR10.1 reference(ranging from 45 to 52).We completely resolved chromosome(Chr)3 and Chr5 in a telomere-to-telomere manner.Chr4 was completely resolved except the nucleolar organizing regions,which comprise long repetitive DNA fragments.The Chrl centromere(CEN1),reportedly around 9 Mb in length,is particularly challenging to assemble due to the presence of tens of thousands of CEN180 satellite repeats.Using the cutting-edge sequencing data and novel computational approaches,we assembled a 3.8-Mb-long CEN1 and a 3.5-Mb-long CEN2.We also investigated the structure and epigenetics of centromeres.Four clusters of CEN180 monomers were detected,and the centromere-specific histone H3-like protein(CENH3)exhibited a strong preference for CEN180 Cluster 3.Moreover,we observed hypomethylation patterns in CENH3-enriched regions.We believe that this high-quality genome assembly,Col-XJTU,would serve as a valuable reference to better understand the global pattern of centromeric polymorphisms,as well as the genetic and epigenetic features in plants.

Dietary chenodeoxycholic acid improves growth performance and intestinal health by altering serum metabolic profiles and gut bacteria in weaned piglets

Nutritional diarrhea and subsequent performance degradation in weaned piglets are major challenges for the pig industry.Bile acids(BA)can be added to the diet as emulsifiers.This experiment was conducted to investigate the effects of chenodeoxycholic acid(CDCA),a major primary BA,on growth performance,serum metabolic profiles and gut health in weaned piglets.A total of 72 healthy weaned piglets were randomly assigned to the control(CON)and the CDCA groups,which were feed a basal diet and the basal diet supplemented with 200 mg/kg CDCA for 30 d,respectively.Our results demonstrated that CDCA significantly increased final BW and average daily gain(ADG),decreased feed-to-gain(F:G)ratio and tended to reduce diarrhea incidence.In addition,CDCA increased the villus height-to-crypt depth(V:C)ratio,elevated goblet cell numbers and the expression of tight junction proteins,suggesting the enhancement of intestinal barrier function.As an emulsifier,CDCA increased jejunal lipase activity and the mRNA expression of pancreatic lipases.CDCA supplementation also altered the serum metabolic profiles,including increasing the levels of indole 3-acetic acid,N'-formylkynurenine and theobromine that were beneficial for gut health.Moreover,the relative abundance of 2 beneficial gut bacteria,Pre-votella 9 and Prevotellaceae TCG-001,were increased,whereas the relative abundance of a harmful bacteria,Dorea,was decreased in the gut of weaned piglets supplemented with CDCA.Importantly,the altered serum metabolic profiles showed a strong correlation with the changed gut bacteria.In conclusion,CDCA improved the growth performance of weaned piglets by improving intestinal morphology and barrier function,and enhancing lipid digestion,accompanied by alterations of serum metabolic profiles,and changes in relative abundance of certain gut bacteria.

Mako:A Graph-based Pattern Growth Approach to Detect Complex Structural Variants

Complex structural variants(CSVs) are genomic alterations that have more than two breakpoints and are considered as the simultaneous occurrence of simple structural variants.However,detecting the compounded mutational signals of CSVs is challenging through a commonly used model-match strategy.As a result,there has been limited progress for CSV discovery compared with simple structural variants.Here,we systematically analyzed the multi-breakpoint connection feature of CSVs,and proposed Mako,utilizing a bottom-up guided model-free strategy,to detect CSVs from paired-end short-read sequencing.Specifically,we implemented a graph-based pattern growth approach,where the graph depicts potential breakpoint connections,and pattern growth enables CSV detection without pre-defined models.Comprehensive evaluations on both simulated and real datasets revealed that Mako outperformed other algorithms.Notably,validation rates of CSVs on real data based on experimental and computational validations as well as manual inspections are around 70%,where the medians of experimental and computational breakpoint shift are 13 bp and 26 bp,respectively.Moreover,the Mako CSV subgraph effectively characterized the breakpoint connections of a CSV event and uncovered a total of 15 CSV types,including two novel types of adjacent segment swap and tandem dispersed duplication.Further analysis of these CSVs also revealed the impact of sequence homology on the formation of CSVs.Mako is publicly available at https://github.com/xjtu-omics/Mako.

AKG/OXGR1 promotes skeletal muscle blood flow and metabolism by relaxing vascular smooth muscle

In response to contraction during exercise,skeletal muscle growth and metabolism are dynamically regulated by nerve action,blood flow,and metabolic feedback.α-Ketoglutarate(AKG),a bioactive intermediate in the tricarboxylic acid cycle released during exercise,has been shown to promote skeletal muscle hypertrophy.However,the underlying mechanism of AKG in regulating skeletal muscle development and metabolism is still less known.2-Oxoglutarate receptor 1(OXGR1),the endogenous AKG receptor,is found to be distributed in the vascular smooth muscle(VSM)of skeletal muscles.OXGR1 knockout results in skeletal muscle atrophy,accompanied by decreased expression of myosin heavy chain I(MyHC I),capillary density,and endurance exercise capacity.Furthermore,the study found that dietary AKG supplementation increased mice endurance exercise distance,MyHC I/MyHC IIb ratio,arteriole,and capillary densities in skeletal muscle.Meanwhile,acute AKG administration gradually increased the blood flow in the lower limbs.Further,by using OXGR1 global knockout and OXGR1 VSM-specific(MYH11-Cre×OXGR1-FloxP)knockdown models,we found that OXGR1 in VSM is essential for AKG-induced improvement of skeletal muscle performances.According to the in vitro study,AKG expanded the cell area in VSM with a decreased intracellular pH by OXGR1.Our results demonstrated a novel role of AKG/OXGR1 in VSM of skeletal muscle to regulate blood flow and then enhance slow muscle fiber conversion and capillarization.These findings provide a theoretical basis for the AKG/OXGR1 signaling pathway to maintain human muscle function and improve meat production and livestock and poultry meat quality.

Smooth muscle AKG/OXGR1 signaling regulates epididymal fluid acid–base balance and sperm maturation

Infertility is a global concern attributed to genetic defects,lifestyle,nutrition,and any other factors that affect the local metabolism and niche microenvironment of the reproductive system.2-Oxoglutarate receptor 1(OXGR1)is abundantly expressed in the testis;however,its cellular distribution and biological function of OXGR1 in the male reproductive system remain unclear.In the current study,we demonstrated that OXGR1 is primarily expressed in epididymal smooth muscle cells(SMCs).Aging and heat stress significantly reduced OXGR1 expression in the epididymis.Using OXGR1 global knockout and epididymal-specific OXGR1 knockdown models,we revealed that OXGR1 is essential for epididymal sperm maturation and fluid acid–base balance.Supplementation ofα-ketoglutaric acid(AKG),the endogenous ligand of OXGR1,effectively reversed epididymal sperm maturation disorders caused by aging and heat stress.Furthermore,in vitro studies showed that AKG markedly stimulated the release of instantaneous intracellular calcium from epididymal SMCs and substantially reduced the pH_(i) value in the epididymal SMCs via OXGR1.Mechanistically,we discovered that AKG/OXGR1 considerably increased the expression of Na^(+)/HCO_(3)^(−)cotransporter(NBCe1)mRNA in the epididymal SMCs,mediated by intracellular calcium signaling.The local AKG/OXGR1 system changed the epididymal fluid pH value and HCO_(3)^(−)concentration,thereby regulating sperm maturation via intracellular calcium signaling and NBCe1 mRNA expression.This study for the first time reveals the crucial role of OXGR1 in male fertility and sheds light on the applicability of metabolic intermediates in the nutritional intervention of reproduction.