基于NiZn层状双金属氢氧化物制备高效电催化CO_(2)还原的原子分散Ni-N-C催化剂

大气中CO_(2)浓度不断上升导致大量的环境问题,如冰川融化、温室效应、极端天气等,利用电化学方法将CO_(2)经还原反应(CO_(2)RR)转化为有价值的燃料或化学品是解决该问题的可行策略.由于CO_(2)具有稳定的化学键(C=O,806 kJ mol^(-1)),需设计具有优异活性和高选择性的催化剂.近年研究结果表明,过渡金属锚定在N掺杂碳载体上而制得的催化剂(M-N-C)具有较高的原子利用率、独特的活性金属中心电子结构以及存储量丰富,因而被认为是CO_(2)还原为CO的理想电催化剂.目前已经提出了多种方法来制备M-N-C催化剂,包括原子层沉积、基于金属-有机骨架的离子交换、基于载体修饰策略的吸附固化和受限热解.然而,这些方法存在制备过程繁琐或难以大规模生产的问题.同时,采用高温热解制备的M-N-C催化剂,金属活性位点易被其致密的结构包裹,难以完全暴露出来.但有效的活性位点对M-N-C的催化性能起着至关重要的作用,因此有必要研制一种简便、高效的方法来抑制金属原子聚集.超薄二维碳骨架已被证明可以缩短反应物的扩散路径并有利于暴露催化剂活性位点.本文将NiZn层状双金属氢氧化物(NiZn-LDHs)在多羟基化合物中进行剥离形成单层,同时通过控制单层NiZn-LDHs、多羟基化合物和三聚氰胺共同热解,宏量化制得Ni-N-C催化剂.X射线衍射(XRD)和透射电子显微镜(TEM)结果表明,在焙烧过程中,可通过改变单层NiZn-LDHs在多羟基化合物中的含量控制Ni-N-C材料中镍纳米颗粒的生成;焙烧过程中Zn挥发能使Ni-N-C材料形成更多中孔,增加碳骨架比表面积和孔径.中孔通道和碳基底超薄特性结合可以促进CO_(2)向内部活性位点扩散,增加反应物与活性位点的接触.XPS结果表明,Ni-N-C材料中Ni原子通过与N配位,锚定在超薄碳骨架上,且存在Niδ+中心(0<δ<2).X射线近边吸收和扩展X射线吸收精细结构分析表明,Ni-N-C-1中的Ni处于低价态(0<δ<2),这与XPS分析一致,且Ni为原子级分散;小波变换分析表明,Ni和N的配位数为3.9.利用H型电解池评估Ni-N-C材料电催化CO_(2)还原性能表明,Ni-N-C-1具有优异的CO_(2)还原活性,在-0.6至-1.0 V电位范围内,FE_(CO)都大于90%,且在-4.9 V时,FE_(CO)为95.2%,CO电流密度为24 mA cm^(-2);在-0.8 V电位,工作25 h后Ni-N-C-1的CO电流密度基本保持不变,说明Ni-N-C-1为稳定的CO_(2)RR催化剂.通过密度泛函理论计算研究了Ni-N-C材料电催化CO_(2)还原为CO的电化学演化历程,结果表明,该反应过程分四个步骤:CO_(2)吸附到单个Ni原子位点上;转移形成*COOH的质子/电子对;*COOH在释放H_(2)O的同时获得质子形成*CO;*CO从Ni位点解吸.相应步骤的吉布斯自由能分别为0.54,1.69,-0.99和-0.98 eV.Ni-N-C中Ni原子与配位N原子之间的强相互作用导致Ni原子的电子损失,Ni原子有0.85 e缺陷,周围的N原子有0.15 e堆积,这有利于CO_(2)的吸附.总之,本文采用单层NiZn-LDHs为金属源,开发了一种简便且可宏量化制备CO_(2)RR单原子催化剂的新方法.

Improved Ant Colony Algorithm for Vehicle Scheduling Problem in Airport Ground Service Support

Support vehicles are part of the main body of airport ground operations,and their scheduling efficiency directly impacts flight delays.A mathematical model is constructed and the responsiveness of support vehicles for current operational demands is proposed to study optimization algorithms for vehicle scheduling.The model is based on the constraint relationship of the initial operation time,time window,and gate position distribution,which gives an improvement to the ant colony algorithm(ACO).The impacts of the improved ACO as used for support vehicle optimization are compared and analyzed.The results show that the scheduling scheme of refueling trucks based on the improved ACO can reduce flight delays caused by refueling operations by 56.87%,indicating the improved ACO can improve support vehicle scheduling.Besides,the improved ACO can jump out of local optima,which can balance the working time of refueling trucks.This research optimizes the scheduling scheme of support vehicles under the existing conditions of airports,which has practical significance to fully utilize ground service resources,improve the efficiency of airport ground operations,and effectively reduce flight delays caused by ground service support.

Development and prospects of degradable magnesium alloys for structural and functional applications in the fields of environment and energy

Magnesium and its alloys have such advantages with lightweight, high specific strength, good damping, high castability and machinability,which make them an attractive choice for applications where weight reduction is important, such as in the aerospace and automotive industries.However, their practical applications are still limited because of their poor corrosion resistance, low high temperature strength and ambient formability. Based on such their property shortcomings, recently degradable magnesium alloys were developed for broadening their potential applications. Considering the degradable Mg alloys for medical applications were well reviewed, the present review put an emphasis on such degradable magnesium alloys for structural and functional applications, especially the applications in the environmental and energy fields. Their applications as fracture ball in fossil energy, sacrificial anode, washing ball, and as battery anodes, transient electronics, were summarized. The roles of alloying elements in magnesium and the design concept of such degradable magnesium alloys were discussed. The existing challenges for extending their future applications are explored.

Plant-inspired biomimetic hybrid PVDF membrane co-deposited by tea polyphenols and 3-amino-propyl-triethoxysilane for high-efficiency oilin-water emulsion separation

Membrane pollution caused by separating oily wastewater is a big challenge for membrane separation technology.Recently,plant-/mussel-inspired interface chemistry has received more and more attention.Herein,a high antifouling poly(vinylidene fluoride)(PVDF)membrane,coated with tea polyphenols(TP,extracted from green tea)and 3-amino-propyl-triethoxysilane(APTES),was developed to purify oil-inwater emulsions.ATR-FTIR,XPS and SEM were used to demonstrate the evolution of surface biomimetic hybrid coatings.The performances of the developed membranes were investigated by pure water permeability and oil rejection for various surfactant-stabilized oil-in-water emulsions.The experimental results revealed that the membrane deposited with a mass ratio of 0.1/0.2 exhibited ultrahigh pure water permeability(14570 L·m^(-2)·h^(-1)·bar^(-1),1 bar=0.1 MPa)and isooctane-in-water emulsion permeability(5391 L·m^(-2)·h^(-1)·bar^(-1))with high separation efficiency(>98.9%).Even treated in harsh environment(acidic,alkaline and saline)for seven days,the membrane still maintained considerable underwater oleophobic property(148°–153°).The fabricated plant-inspired biomimetic hybrid membranes with excellent performances light a broad application prospect in the field of oily wastewater treatment.

Insight into coupled Ni-Co dual-metal atom catalysts for efficient synergistic electrochemical CO_(2)reduction

The development of highly active,selective,and stable electrocatalysts can facilitate the effective implementation of electrocatalytic CO_(2)conversion into fuels or chemicals for mitigating the energy crisis and climate problems.Therefore,it is necessary to achieve the goal through reasonable material design based on the actuality of the operational active site at the molecular scale.Inspired by the stimulating synergistic effect of coupled heteronuclear metal atoms,a novel Ni-Co atomic pairs configuration(denoted as NiN_(3)?CoN_(3)-NC)active site was theoretically screened out for improving electrochemical CO_(2)reduction reaction(CO_(2)RR).The structure of NiN_(3)?CoN_(3)-NC was finely regulated by adjusting Zn content in the precursors Zn/Co/Ni-zeolite imidazolate frameworks(Zn/Co/Ni-ZIFs)and pyrolysis temperature.The structural features of NiN_(3)?CoN_(3)-NC were systematically confirmed by aberration-corrected HAADF-STEM coupled with 3D atom-overlapping Gaussian-function fitting mapping,XAFS,and XRD.The results of theoretical calculations reveal that the synergistic effect of Ni-Co atomic pairs can effectively promote the*COOH intermediate formation and thus the overall CO_(2)RR kinetic was improved,and also restrained the competitive hydrogen evolution reaction.Due to the attributes of Ni-Co atomic pairs configuration,the developed NiN_(3)?CoN_(3)-NC with superior catalytic activity,selectivity,and durability,with a high turnover frequency of 2265 h^(-1)at-1.1 V(vs.RHE)and maximum Faradaic efficiency of 97.7%for CO production.This work demonstrates the great potential of DACs as highly efficient catalysts for CO_(2)RR,provides a useful strategy to design heteronuclear DACs,exploits the synergistic effect of multiple metal sites to facilitate complex CO_(2)RR catalytic reactions,and inspires more efforts to develop the potential of DACs in various fields.

Cost-benefit and discriminant validity of a stepwise dementia case-finding approach in an Asian older adult community

Background Case-finding is a recommended approach for dementia early detection in the community.Aims To investigate the discriminant validity and cost-effectiveness of a stepwise dementia case-finding approach in a Singaporean older adult community.Methods The two-phase study was conducted in the community from 2009 to 2015 in Singapore.A total of 3780 participants(age≥60 years)completed phase I(a brief cognitive screening);918 completed phase II and were included in the final analysis.In phase I,all participants were administered the Abbreviated Mental Test(AMT)and the Progressive Forgetfulness Question(PFQ).Those who screened positive on either test were invited to phase II,whereby the Mini-Mental State Examination(MMSE),Montreal Cognitive Assessment(MoCA)and a formal neuropsychological battery were administered,followed by the research diagnosis of no cognitive impairment,cognitive impairment no dementia(CIND)-Mild(≤2 impaired cognitive domains),CIND-Moderate(>2 impaired domains)or dementia.Receiver operating characteristic curve analyses were conducted for the different cognitive instruments.All discriminant indices were calculated,including sensitivity,specificity,positive and negative predictive values(NPV)and accuracy.Cost-effectiveness analysis was conducted by estimating the amount of screening time needed and the number of older adults requiring re-evaluation in two case-finding scenarios,ie,with or without preselection by the PFQ.Results The stepwise case-finding approach(preselection by the PFQ,then MMSE or MoCA or AMT)showed an excellent NPV(>99%)and accuracy(>86%)for excluding dementia-free cases.Without preselection by the PFQ,screening time for the three cognitive tools were 317.5,317.5 and 254 hours,with 159,302 and 175 screen-positive older adults involved in further evaluation.By adopting the stepwise case-finding approach,total screening time were 156.5,156.5 and 126.2 hours,which decreased by 50.7%,50.7% and 50.3% as compared with those without preselection.Furthermore,after preselection,only 98,167 and 145 screen-positive older adults required further evaluation,corresponding to a reduction of 38.4%,44.7% and 17.1% in the numbers compared with those without preselection.Conclusions A stepwise approach for dementia case-finding should be implemented in the community to minimise the time and resources needed for large-scale early detection of dementia.

Recent advances in elaborate interface regulation of BiVO_(4)photoanode for photoelectrochemical water splitting

Bismuth vanadate(BiVO_(4))is an excellent photoanode material for photoelectrochemical(PEC)water splitting system,possessing high theoretical photoelectrocatalytic conversion efficiency.However,the actual PEC activity and stability of BiVO_(4)are faced with great challenges due to factors such as severe charge recombination and slow water oxidation kinetics at the interface.Therefore,various interface regulation strategies have been adopted to optimize the BiVO_(4)photoanode.This review provides an in-depth analysis for the mechanism of interface regulation strategies from the perspective of factors affecting the PEC performance of BiVO_(4)photoanodes.These interface regulation strategies improve the PEC performance of BiVO_(4)photoanode by promoting charge separation and transfer,accelerating interfacial reaction kinetics,and enhancing stability.The research on the interface regulation strategies of BiVO_(4)photoanode is of great significance for promoting the development of PEC water splitting technology.At the same time,it also has inspiration for providing new ideas and methods for designing and preparing efficient and stable catalytic materials.

Winding Function Theory Based Thrust Calculation on Nested-loop Secondary Linear Machine Adapted to Linear Metro

With advantages of strong drive capability,nested-loop secondary linear machine(NLS-LM)has great potentiality in linear metro.For its secondary structure with multiple loops,it is difficult to calculate the electromagnetic thrust of NLS-LM reasonably.Hence,in this paper,one thrust calculation method is proposed considering variable loop inductance and transient loop current.Firstly,to establish the secondary winding function,the modeling domain is confined to a limited range,and the equivalent loop span is employed by analyzing the coupling relationship between primary and secondary.Then,in order to obtain the secondary flux density,the transient secondary current is solved based on the loop impedance and induced voltage.Finally,the electromagnetic thrust can be calculated reasonably by the given primary current sheet and the calculated secondary flux density.Comprehensive simulations and experiments have demonstrated the effectiveness of the proposed method.

Diagnostic Value of TB-IGRA, PPD, TB-DNA-PCR and TB-Ab in Silicosis Complicated with Tuberculosis

Purpose: The purpose of this article is to investigate the clinical value of TB-IGRA (Tuberculosis-Interferon Gamma Release Assay), PPD (Intradermal Terbuculin Test), TB-DNA-PCR (Tuberculosis-Deoxyribonucleic-Polymerase Chain Reaction) and TB-Ab (Tuberculosis-Antibody) in diagnosing silicosis complicated with pulmonary tuberculosis. Methods: 53 cases of suspected silicosis complicated with pulmonary tuberculosis were selected in the time span ranging from February 2017 to May 2019. TB-IGRA test, PPD test, TB-DNA-PCR and TB-Ab detection were performed. The sensitivity, specificity, positive predictive value and negative predictive value were calculated. Results: Silicosis and pulmonary tuberculosis were diagnosed in 11 cases, with an incidence of 20.75%. The positive rates of TB-IGRA, PPD, TB-DNA-PCR and TB-Ab were 66.04%, 30.19%, 5.67% and 26.42%, respectively. The sensitivity was 90.91%, 81.82%, 27.27% and 54.55% respectively. The specificity was 42.86%, 80.95%, 100% and 80.95% respectively. The positive predictive values were 28.57%, 50%, 100% and 42.86% respectively. The negative predictive values were 94.44%, 91.89%, 84% and 87.18%. The positive rate, sensitivity and negative predictive value of TB-IGRA were the highest, while the specificity of TB-DNA-PCR was the highest yet with low positive rate, sensitivity and positive predictive value. Conclusion: The positive rate and sensitivity of TB-IGRA were high, yet with poor specificity, so it was impossible to judge whether the cases belonged to active pulmonary tuberculosis. The combination of PPD and TB-DNA-PCR could improve the sensitivity, specificity and positive predictive value, and the diagnostic accuracy of active pulmonary tuberculosis, which showed satisfactory clinical value.

共建与区域产学研联合办学背景下应用化学专业建设与成效

针对地方高校学科、专业与课程建设各自为政,难于提升人才培养质量的现象,挖掘区域特色优势,在共建与区域产学研联合办学背景下,对标"双一流"和"新工科"及"双万计划",开展学科、专业与课程一体化建设,构建基于导师加团队、平台、培养方案的科研教学协同三全育人生态体系,建设应用化学国家一流专业,培养复合创新人才。

Diagnostic Value of TB-IGRA, PPD, TB-DNA-PCR and ADA in Tuberculous Pleural Effusion

Objective: To investigate the clinical diagnostic value of TB-IGRA (Tuberculosis-Interferon Gamma Release Assay), PPD (Intradermal Tuberculin Test), TB-DNA-PCR (Tuberculosis-Deoxyribonucleic-Polymerase Chain Reaction) and ADA(Adenosine Aeaminase) in tuberculous pleural effusion. Methods: 60 patients with tuberculous pleural effusion discharged from our department from January 1, 2018 to December 31, 2019 were selected. Moreover, the TB-IGRA in peripheral blood, PPD test, TB-DNA-PCR and ADA in pleural effusion were detected. Subsequently, the positive rate, negative rate, sensitivity and omission diagnostic rate of TB-IGRA, PPD, TB-DNA-PCR, ADA and combined TB-IGRA were calculated. Results: The positive rate and sensitivity of TB-IGRA, PPD,TB-DNA-PCR, and ADA were 95%, 71.67%, 5% and 86.67% respectively. The omission diagnostic rate was 5%, 28.33%, 95% and 13.33%. TB-IGRA showed the highest positive rate and sensitivity, and TB-DNA-PCR represented the highest omission diagnostic rate. The sensitivity of TB-IGRA + PPD was 98.33%, while the omission diagnostic rate was 51.67%. The sensitivity of TB-IGRA + TB-DNA-PCR was 95%, while the omission diagnostic rate was 5%. The sensitivity of TB-IGRA + ADA was 100%, while the omission diagnostic rate was 0%. In addition, the TB-IGRA + ADA had the highest sensitivity and the lowest omission diagnostic rate. Conclusion: TB-IGRA has high positive rate, high sensitivity and low omission diagnostic rate, which is superior to the traditional sputum test for tuberculosis. Notably, the combination of PPD, TB-DNA-PCR, ADA is capable of improving the diagnosis rate, and the diagnosis rate can reach 100% when combined with ADA, which is able to provide solid diagnostic value in clinical practice.

Effect of Rifapentine and Rifampicin on Anti-Tuberculosis

Objective: To investigate the clinical effect of rifapentine and rifampicin in the treatment of pulmonary tuberculosis. Methods: Seventy-two cases of patients with initial treatment of pulmonary tuberculosis who attended the First Hospital Affiliated to Hebei North University from February 2017 to August 2019 were selected. They were randomly divided into observation group and control group, with 36 cases in each group. The observation group was treated with isoniazid + rifapentine + ethambutol, while the control group was treated with isoniazid + rifampicin + ethambutol. The symptom relief, image absorption and adverse reactions were compared between the two groups. Results: The rate of symptom relief was 86.11% in the observation group and 94.44% in the control group, P < 0.05, which was statistically significant. Rifampin was more helpful than rifapentine in relieving clinical symptoms. The lesion absorption rate was 77.79% in the observation group and 88.89% in the control group, P < 0.05, and the difference was statistically significant. Rifampin was more beneficial to the absorption of TB lesions than rifapentine. The incidence of adverse reactions in the observation group was 16.67% much lower than that in the control group, which was 38.89%, indicating that the adverse reactions of rifapentine were less. Conclusion: Rifampicin is superior to rifapentine in clinical symptom relief and lesion absorption, but the incidence of adverse reactions is high.

金属-有机框架衍生的多功能光催化剂

在光催化过程中,光催化剂被太阳能激发产生光生电子和空穴,来实现环境净化或能量转换,是应对全球变暖和能源短缺的有效途径之一.然而,光催化技术面临的主要瓶颈问题是光生载流子的低分离效率和高反应能垒.而催化剂本身的特性对这一点起到了决定性的作用.因此,催化剂的合理设计和改性是提高光催化效率的关键.金属有机框架(MOFs)是一类由金属节点和有机配体组成的新型结晶多孔材料.基于结构多样性、超高比表面积、形状和尺寸可调的纳米孔或纳米通道等优异的特性,MOFs基材料在光催化领域引起了广泛关注.然而,MOFs的主要问题之一是低导电性和稳定性,这限制了其更广泛应用.正是由于MOFs的不稳定性,其可以作为牺牲模板制备纳米材料.由MOFs衍生的纳米材料继承了MOFs的优异特性,同时避免了MOFs较差的导电性和稳定性的问题.并且可以通过选择特定的金属节点和有机配体对MOFs衍生的纳米材料进行调控,从而实现光催化剂的多功能性.因此,MOFs衍生物在光催化领域展现出更广阔的应用前景.而且MOFs衍生物不仅可以作为半导体光催化剂,还可以作为光催化析氢、CO_(2)还原、污染物降解等反应的助催化剂.本文重点介绍MOFs衍生物在光催化领域的多功能应用.从MOFs衍生物的制备、修饰和应用等方面对近年来的研究进行了分析和总结.最后,对MOFs衍生物应用于光催化领域的挑战进行了分析,并对未来发展和机遇进行了展望,以期为该领域的进一步研究提供更多参考,并带来新的启示.

Influence of chromium modification on the properties of MnO_x-FeO_x catalysts for the low-temperature selective catalytic reduction of NO by NH_3

Catalytic properties of MnOx -FeOx complex oxide (hereafter denoted as Mn-Fe) catalysts modified with different loadings of chromium oxide were investigated by using the combination of physico-chemical techniques, such as N2 physisorption, X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), in situ Fourier transform infrared spectroscopy (in situ FT-IR) and temperature-programmed reduction (TPR) and their catalytic activities were evaluated with the selective catalytic reduction (SCR) of NOx by NH3 . It was found that with the addition of Cr, more NO could be removed in the low-temperature window (below 120℃). Among the tested catalysts, Mn-Fe-Cr (2 : 2 : 1) catalyst exhibited the best catalytic performance at 80℃ with the NO conversion higher than 90%. The combination of the reaction and characterization results indicated that (1) the strong interaction among tertiary metal oxides existed in the catalysts when Cr was appropriately added, which made the active components better dispersed with less agglomeration and sintering and the largest BET specific surface area could be obtained; (2) Cr improved the low-temperature reducibility of the catalyst and promoted the formation of the active intermediate (-NH+3 ), which favored the low-temperature SCR reaction.

Matrilineal History of the Rana longicrus Species Group(Rana,Ranidae,Anura) and the Description of a New Species from Hunan,southern China

Fieldwork in Jiemuxi National Nature Reserve,Hunan,China,discovered morphologically indistinguishable groups of brown frogs that bred at different,exclusive times of the year.A principal components analysis of morphometric data,molecular analyses,and the exclusive breeding season suggested the occurrence of two species.The population that breeds during the winter was found to be an undescribed species and was subsequently described as Rana jiemuxiensis sp.nov.The new cryptic species can be identified from its congeners at the same locality by having a different breeding season and a divergent DNA barcode.Six major lineages of brown frogs were resolved with high nodal support.Rana japonica,R.chaochiaoensis,R.omeimontis,and R.jiemuxiensis have independent maternal lineages.Rana hanlunica and R.maoershanensis have essentially identical maternal lineages and they appear to represent the same species.The validity of the species R.longicrus,R.zhenhaiensis,and R.culaiensis and their genealogical relationships are not resolved and deserve further study.The genealogy indicates that sympatric cryptic lineages probably widely exist in the R.longicrus group.This highlights the importance of future more fine-scaled samplings and the inclusion of nuclear genes.

A New Species of the Genus Thermophis(Serpentes: Colubridae) from Shangri-La, Northern Yunnan, China, with a Proposal for an Eclectic Rule for Species Delimitation

The hot-spring snakes, Thermophis, were previously known only from the Tibet Autonomous Region and Western Sichuan, China. During the past two years, three adult hot-spring snakes(2 females, 1 male) were sampled in Shangri-La, northern Yunnan, China, thus expanding their known distribution region towards the southeast. This site is the southeastern-most corner of the Tibetan Plateau and the southernmost tip of the Hengduan Mountains(Mts.). Phylogenetic analysis of mitochondrial(mt) and nuclear(n) DNA segments suggested that the three specimens belong to the genus of Thermophis. Morphologically, the new species is more similar to T. zhaoermii. However, it is distinguished from T. zhaoermii in the number of maxillary teeth(15), distance between the two eyes/head width, rostral width/height, mental width/height, in one character limited to female: head width/length, and in four characters restricted to male: occurrence of the reduction from 10 to 8(8 to 6, 6 to 4) scales in each dorsal row on the tail. There are differences in morphology, genetics(mt DNA, n DNA), and geography between the putative new species and T. zhaoermii, the new species meets our proposed eclectic and feasible "four-differences" rule.

Editorial

As Zoological Research enters its 33rd year of publication,let us reflect back on the last three decades of dramatic change to China and the scientific community. In the latter half of the 20th century, scientific research was almost exclusively published in the United States or Europe. We started

Summary of Laurasiatheria(Mammalia)Phylogeny

Laurasiatheria is one of the richest and most diverse superorders of placental mammals.Because this group had a rapid evolutionary radiation,the phylogenetic relationships among the six orders of Laurasiatheria remain a subject of heated debate and several issues related to its phylogeny remain open.Reconstructing the true phylogenetic relationships of Laurasiatheria is a significant case study in evolutionary biology due to the diversity of this suborder and such research will have significant implications for biodiversity conservation.We review the higher-level(inter-ordinal)phylogenies of Laurasiatheria based on previous cytogenetic,morphological and molecular data,and discuss the controversies of its phylogenetic relationship.This review aims to outline future researches on Laurasiatheria phylogeny and adaptive evolution.

Genome-wide identification of functional enhancers and their potential roles in pig breeding

Background:The pig is an economically important livestock species and is a widely applied large animal model in medical research.Enhancers are critical regulatory elements that have fundamental functions in evolution,development and disease.Genome-wide quantification of functional enhancers in the pig is needed.Results:We performed self-transcribing active regulatory region sequencing(STARR-seq)in the porcine kidney epithelial PK15 and testicular ST cell lines,and reliably identified 2576 functional enhancers.Most of these enhancers were located in repetitive sequences and were enriched within silent and lowly expressed genes.Enhancers poorly overlapped with chromatin accessibility regions and were highly enriched in chromatin with the repressive histone modification H3K9me3,which is different from predicted pig enhancers detected using ChIP-seq for H3K27ac or/and H3K4me1 modified histones.This suggests that most pig enhancers identified with STARR-seq are endogenously repressed at the chromatin level and may function during cell type-specific development or at specific developmental stages.Additionally,the PPP3CA gene is associated with the loin muscle area trait and the QKI gene is associated with alkaline phosphatase activity that may be regulated by distal functional enhancers.Conclusions:In summary,we generated the first functional enhancer map in PK15 and ST cells for the pig genome and highlight its potential roles in pig breeding.