Research on Soil Conservation and Improvement Technology in Zhaoyang District

The environment of tobacco-growing soil directly affects the yield and quality of tobacco leaves.In order to solve problems of tobacco-growing soil degradation,low organic matter content and unbalanced soil nutrient supply and promote sustainable and healthy development of tobacco production,this paper comprehensively discussed conservation and improvement techniques of tobacco-growing soil based on existing problems in Zhaoyang District,aiming to provide reference for tobacco-growing soil conservation.

双注意力随机选择全局上下文细粒度识别网络

针对细粒度图像识别任务中易忽视微小潜在性特征且外观差异细微等问题,提出一种基于双注意力随机选择全局上下文细粒度识别网络。首先,使用ConvNeXt作为主干网络,提出双注意力随机选择模块,对不同阶段提取到的特征进行通道随机选择和空间随机选择,使网络能够关注到其他潜在微小判别性特征;其次,利用全局上下文注意力模块将深层特征的语义信息融合到中间层,增强中间层定位微小特征的能力;最后,提出一种多分支损失,对中间层、深层和拼接层特征引入分类损失,结合不同分支提取到的特征,诱导网络获得多样性的判别特征。所提网络在Stanford-cars、CUB-200-2011、FGVC-Aircraft 3个公开细粒度数据集和真实场景下车型数据集VMRURS上分别达到了95.2%、92.1%、94.0%和97.0%的识别准确率,其性能相比其他对比方法有较大幅度提升。

不同影像检查方法对颈动脉内膜切除术与颈动脉支架植入术后颈动脉狭窄程度的诊断价值

目的 探讨不同影像检查方法对颈动脉内膜切除术(CEA)与颈动脉支架植入术(CAS)后颈动脉狭窄程度的诊断价值。方法 收集2018年2月到2020年1月承德医学院附属医院行CEA或CAS的98例颈动脉狭窄患者的临床资料,按照治疗方式的不同将其分为CEA组(n=48)和CAS组(n=50)。比较两组患者手术前后颈动脉狭窄程度及住院期间至随访2年内不良心血管事件发生率。以头颈主动脉弓机断层扫描血管成像(CTA)为诊断金标准,比较彩色多普勒超声、磁共振成像检查颈动脉狭窄程度的准确度。结果 手术前后,两组患者颈动脉狭窄各程度比较,差异均无统计学意义(P﹥0.05)。术后,两组患者中、重度颈动脉狭窄均低于本组术前,差异均有统计学意义(P﹤0.05)。CEA组患者不良心血管事件总发生率为2.08%(1/48),与CAS组患者的4.00%(2/50)比较,差异无统计学意义(P﹥0.05)。彩色多普勒超声检查颈动脉狭窄程度准确度为95.92%(94/98),与磁共振成像检查的94.90%(93/98)比较,差异无统计学意义(P﹥0.05)。结论 彩色多普勒超声和磁共振成像检查对颈动脉狭窄程度的诊断准确度均较高,CEA、CAS治疗颈动脉狭窄均具有较好疗效,且术后不良心血管事件发生率较低。

过渡态理论对Arrhenius公式的诠释——以硝酸异丙酯与自由基反应为例

大学物理化学教学中,Arrhenius公式阐述了反应的速率常数与温度及活化能的关系,但是,单纯从公式的表达式进行讲解,难免枯燥乏味,不利于学生理解和掌握。本文以硝酸异丙酯与Cl原子、OH和NO_(3)自由基反应为例,基于反应的势能面,用过渡态理论计算不同温度下反应的速率常数,直观形象地分析了在不同反应能垒时,反应速率常数随温度的变化情况,以期帮助学生从本质上理解Arrhenius公式,拓宽他们的知识面,培养其科学探究的意识和能力。

利用数据中心余热供热的系统设计与分析

数据中心余热供热是提高数据中心能源利用效率和实现冬季清洁供暖的重要途径。本文提出了一种适用于数据中心的长距离供热系统,在热源和热汇处设置多级热泵以增大供热管网供回水温差,并使用储热装置保障数据中心和供热系统的安全性,提高数据中心余热利用率。以张家口某数据中心为例进行了分析,该系统初投资为50.21元/m^(2),运行费用为26.37元/GJ,投资回收期约为5.31 a,具有较好的经济性和节能减排效果。

准噶尔盆地风城组硅硼钠石中包裹体特征及其地质意义

准噶尔盆地风城组的含钠白云岩和油页岩是重要的油气藏和主要的烃源岩,正确认识硅硼钠石的成因,对明确含钠白云岩的成因以及预测优质白云岩储层具有重要意义。为探究风城组白云岩、硅质岩的成因,本文选取准噶尔盆地风城组60件岩芯样品磨片制样,通过观察硅硼钠石及其中包裹体岩相学特征,再结合包裹体显微测温,得到包裹体均一温度和盐度(w(NaCleq))等多项参数,探讨了硅硼钠石成因以及其对寄主岩石成因的指示意义。结果表明:(1)风城组泥页岩、白云岩和硅质岩中均出现了团块状硅硼钠石和似斑状硅硼钠石,且硅硼钠石中的包裹包括油包裹体和流体包裹体两大类,具体类型为气液两相的油包裹体(O型)、纯液相油包裹体(PO型)、气液两相流体包裹体(W型)、纯液相流体包裹体(PW型);(2)从深部到浅部,团块状硅硼钠石的均一温度峰值范围由108.8~129.4℃变为72.8~89.8℃,似斑状硅硼钠石的均一温度范围由50.4~86.4℃变为54.2~66.4℃;(3)团块状硅硼钠石中W型包裹体盐度为8.41%~18.22%,无明显集中范围;似斑状为6.88%~15.37%,流体在沉积岩形成过程中属于高盐度流体。此次通过对准噶尔盆地风城组硅硼钠石岩相学和包裹体研究,结合前人对研究区风城组硅质岩地球化学研究,综合表明,硅硼钠石寄主岩石属于碱性盐湖背景下,中低温热液流体与碱性盐湖水混合沉积成因。

The role of exosomes in adult neurogenesis:implications for neurodegenerative diseases

Exosomes are cup-shaped extracellular vesicles with a lipid bilayer that is approximately 30 to 200 nm in thickness.Exosomes are widely distributed in a range of body fluids,including urine,blood,milk,and saliva.Exosomes exert biological function by transporting factors between different cells and by regulating biological pathways in recipient cells.As an important form of intercellular communication,exosomes are increasingly being investigated due to their ability to transfer bioactive molecules such as lipids,proteins,mRNAs,and microRNAs between cells,and because they can regulate physiological and pathological processes in the central nervous system.Adult neurogenesis is a multistage process by which new neurons are generated and migrate to be integrated into existing neuronal circuits.In the adult brain,neurogenesis is mainly localized in two specialized niches:the subventricular zone adjacent to the lateral ventricles and the subgranular zone of the dentate gyrus.An increasing body of evidence indicates that adult neurogenesis is tightly controlled by environmental conditions with the niches.In recent studies,exosomes released from different sources of cells were shown to play an active role in regulating neurogenesis both in vitro and in vivo,thereby participating in the progression of neurodegenerative disorders in patients and in various disease models.Here,we provide a state-of-the-art synopsis of existing research that aimed to identify the diverse components of exosome cargoes and elucidate the therapeutic potential of exosomal contents in the regulation of neurogenesis in several neurodegenerative diseases.We emphasize that exosomal cargoes could serve as a potential biomarker to monitor functional neurogenesis in adults.In addition,exosomes can also be considered as a novel therapeutic approach to treat various neurodegenerative disorders by improving endogenous neurogenesis to mitigate neuronal loss in the central nervous system.

深低温保存下高效抗冻多肽的合理设计和机理探讨

The development of effective antifreeze peptides to control ice growth has attracted a significant amount of attention yet still remains a great challenge.Here,we propose a novel design method based on in-depth investigation of repetitive motifs in various ice-binding proteins(IBPs)with evolution analysis.In this way,several peptides with notable antifreeze activity were developed.In particular,a designed antifreeze peptide named AVD exhibits ideal ice recrystallization inhibition(IRI),solubility,and biocompatibility,making it suitable for use as a cryoprotective agent(CPA).A mutation analysis and molecular dynamics(MD)simulations indicated that the Thr6 and Asn8 residues of the AVD peptide are fundamental to its ice-binding capacity,while the Ser18 residue can synergistically enhance their interaction with ice,revealing the antifreeze mechanism of AVD.Furthermore,to evaluate the cryoprotection potential of AVD,the peptide was successfully employed for the cryopreservation of various cells,which demonstrated significant post-freezing cell recovery.This work opens up a new avenue for designing antifreeze materials and provides peptide-based functional modules for synthetic biology.

MiR-142-3p Regulates ILC1s by Targeting HMGB1 via the NF-κB Pathway in a Mouse Model of Early Pregnancy Loss

Objective Innate lymphoid cells(ILCs)are a class of newly discovered immunocytes.Group 1 ILCs(ILC1s)are identified in the decidua of humans and mice.High mobility group box 1(HMGB1)is predicted to be one of the target genes of miR-142-3p,which is closely related to pregnancy-related diseases.Furthermore,miR-142-3p and HMGB1 are involved in regulating the NF-κB signaling pathway.This study aimed to examine the regulatory effect of miR-142-3p on ILC1s and the underlying mechanism involving HMGB1 and the NF-κB signaling pathway.Methods Mouse models of normal pregnancy and abortion were constructed,and the alterations of ILC1s,miR-142-3p,ILC1 transcription factor(T-bet),and pro-inflammatory cytokines of ILC1s(TNF-α,IFN-γand IL-2)were detected in mice from different groups.The targeting regulation of HMGB1 by miR-142-3p in ILC1s,and the expression of HMGB1 in normal pregnant mice and abortive mice were investigated.In addition,the regulatory effects of miR-142-3p and HMGB1 on ILC1s were detected in vitro by CCK-8,Annexin-V/PI,ELISA,and RT-PCR,respectively.Furthermore,changes of the NF-κB signaling pathway in ILC1s were examined in the different groups.For the in vivo studies,miR-142-3p-Agomir was injected in the uterus of abortive mice to evaluate the abortion rate and alterations of ILC1s at the maternal-fetal interface,and further detect the expression of HMGB1,pro-inflammatory cytokines,and the NF-κB signaling pathway.Results The number of ILC1s was significantly increased,the level of HMGB1 was significantly upregulated,and that of miR-142-3p was considerably downregulated in the abortive mice as compared with the normal pregnant mice(all P<0.05).In addition,miR-142-3p was found to drastically inhibit the activation of the NF-κB signaling pathway(P<0.05).The number of ILC1s and the levels of pro-inflammatory cytokines were significantly downregulated and the activation of the NF-κB signaling pathway was inhibited in the miR-142-3p Agomir group(all P<0.05).Conclusion miR-142-3p can regulate ILC1s by targeting HMGB1 via the NF-κB signaling pathway,and attenuate the inflammation at the maternal-fetal interface in abortive mice.

适用于降解样本的201个遗传标记检测体系的构建和验证

近年来,法医实践中复杂案件数量逐渐增多,需要联合使用短串联重复序列(short tandem repeat,STR)、单核苷酸多态性(single nucleotide polymorphisms,SNP)、插入缺失多态性(insertion/deletion polymorphism,InDel)、微单倍型(microhaplotype,MH)等不同类型的遗传标记,为案件提供更多的参考信息。本研究筛选了24个常染色体STR(autosomes STR,A-STR)、24个Y染色体STR(Y-STR)、110个A-SNP、24个Y-SNP、9个A-InDel、1个Y-InDel、8个MH和Amelogenin共201个遗传标记,建立二代测序检测体系HID_AM Panel v1.0。根据DNA分析方法科学工作组(Scientific Working Group on DNA Analysis Methods,SWGDAM)的验证指南,对该体系的重复性、准确性、灵敏度、对降解样本的适用性、物种特异性、抗抑制性等指标进行评估。本体系分型结果与基于毛细管电泳方法检测的48个STR和Amelogenin结果完全一致,与ForenSeq™ DNA Signature Prep Kit重合的79个SNP分型结果完全一致;当DNA加入量不低于200 pg时可获得全部等位基因分型结果;当检测降解指数大于15.87的模拟降解样本时,检出成功率明显高于GlobalFilerTM PCR扩增试剂盒;当体系内血红素浓度不高于40μmol/L、靛蓝浓度不高于2 mmol/L、或腐殖酸浓度不高于15 ng/μL时,扩增无明显抑制;鸭、鼠、牛、兔、鸡的DNA特异性扩增较少;常规样本中STR检出率达99.74%,SNP、InDel、MH全部检出。综上所述,本研究建立的检测体系具有较高的准确性、灵敏度、物种特异性和抗抑制性,适用于降解样本的个体识别。

慢性阻塞性肺疾病患者运动恐惧的评估与干预研究进展

从慢性阻塞性肺疾病患者运动恐惧的现状及影响因素、评估工具、干预方法进行综述,旨在提高临床护理人员的重视程度,及时发现患者运动恐惧现象,采取针对性干预措施指导临床工作,降低患者运动恐惧水平,促进患者运动行为,从而提高慢性阻塞性肺疾病患者的生活质量和疾病预后。

High-pressure minerals and new lunar mineral changesite-(Y) in Chang’e-5 regolith

Forty-five years after the Apollo and Luna missions, China’s Chang’e-5 (CE-5) mission collected ∼1.73 kg of new lunar materials from one ofthe youngest basalt units on the Moon. The CE-5 lunar samples provide opportunities to address some key scientific questions related to theMoon, including the discovery of high-pressure silica polymorphs (seifertite and stishovite) and a new lunar mineral, changesite-(Y). Seifertitewas found to be coexist with stishovite in a silica fragment from CE-5 lunar regolith. This is the first confirmed seifertite in returned lunarsamples. Seifertite has two space group symmetries (Pnc2 and Pbcn) and formed from an α-cristobalite-like phase during “cold” compressionduring a shock event. The aftershock heating process changes some seifertite to stishovite. Thus, this silica fragment records different stagesof an impact process, and the peak shock pressure is estimated to be ∼11 to 40 GPa, which is much lower than the pressure condition forcoexistence of seifertite and stishovite on the phase diagram. Changesite-(Y), with ideal formula (Ca_(8)Y)◻Fe^(2+)(PO_(4))_(7) (where ◻ denotes avacancy) is the first new lunar mineral to be discovered in CE-5 regolith samples. This newly identified phosphate mineral is in the form ofcolumnar crystals and was found in CE-5 basalt fragments. It contains high concentrations of Y and rare earth elements (REE), reaching upto ∼14 wt. % (Y,REE)2O3. The occurrence of changesite-(Y) marks the late-stage fractional crystallization processes of CE-5 basalts combinedwith silicate liquid immiscibility. These new findings demonstrate the significance of studies on high-pressure minerals in lunar materials andthe special nature of lunar magmatic evolution.

外周血RDW、ox-LDL、Egr3水平与CAS病变程度的关系及预测心肌梗死的价值

目的 分析外周血红细胞体积分布宽度(RDW)、氧化低密度脂蛋白(ox-LDL)、早期生长反应因子3(Egr3)水平与冠状动脉粥样硬化(CAS)病变程度的关系,并探讨其预测急性心肌梗死(AMI)的价值。方法 选取2021年5月至2022年2月河南省第二人民医院收治的120例CAS患者作为研究组,另选取同期60例因胸痛入院但冠状动脉造影(CAG)检查结果正常的患者作为对照组。比较两组患者的一般资料、外周血RDW、ox-LDL、Egr3水平,并比较研究组不同CAS病变程度患者外周血RDW、ox-LDL、Egr3水平,采用Spearman相关系数分析外周血RDW、ox-LDL、Egr3水平与CAS病变程度的相关性。比较随访12个月内发生与未发生AMI患者入院时外周血RDW、ox-LDL、Egr3水平及心肌标志物[心肌肌钙蛋白I(cTnI)、肌酸激酶MB同工酶(CK-MB)、氨基末端脑钠肽前体(NT-proBNP)]水平,采用受试者工作特征曲线(ROC)分析RDW、ox-LDL、Egr3、心肌标志物对CAS患者发生AMI的预测价值,将RDW、ox-LDL、Egr3、心肌标志物联合预测AMI作为新预测方案,心肌标志物联合预测AMI作为常规预测方案,比较两种预测方案对AMI的预测价值。结果 研究组患者的外周血RDW、ox-LDL、Egr3水平分别为(21.65±3.79)%、(25.17±4.76)μg/L、(1 715.36±543.81) ng/L,明显高于对照组的(14.87±2.15)%、(1.35±0.43)μg/L、(1 129.48±368.25) ng/L,差异均有统计学意义(P<0.05);外周血RDW、ox-LDL、Egr3水平随着CAS病变程度的增加而逐渐升高,且差异均有统计学意义(P<0.05);经Spearman相关分析结果显示,外周血RDW、ox-LDL、Egr3水平与CAS病变程度呈正相关(P<0.05);发生AMI患者入院时外周血RDW、ox-LDL、Egr3水平、血清c Tn I、CK-MB、NT-proBNP水平明显高于未发生AMI患者,差异均有统计学意义(P<0.05);经ROC分析结果显示,入院时外周血RDW、ox-LDL、Egr3、血清cTnI、CK-MB、NT-proBNP预测CAS患者发生AMI的曲线下面积(AUC)分别为0.735、0.754、0.775、0.737、0.739、0.728,敏感度分别为60.00%、88.00%、64.00%、76.00%、64.00%、72.00%,特异度分别为82.76%、59.77%、83.91%、74.71%、82.76%、66.67%,各指标单独预测AMI的AUC比较差异无统计学意义(P>0.05);与常规预测方案AUC (0.844)比较,新预测方案的AUC (0.949)明显增大,净重新分类指数(NRI)、综合判别改善指数(IDI)均>0。结论 CAS患者外周血RDW、ox-LDL、Egr3水平与CAS病变程度呈正相关,且在预测AMI方面具有一定价值。

Effects of salt and rice flour concentration on microbial diversity and the quality of sour meat,a Chinese traditional meat

This study investigated the effects of salt(3%and 6%,m/m)and rice flour(10%and 20%,m/m)addition in sour meat,a traditional Chinese fermented meat.It was found that salt has greater effect than rice flour addition in spontaneous fermentation.Low-salt groups had lower pH and higher titratable total acid.In the low-salt groups,the dominant genera were Lactobacillus and Lactococcus,whereas Staphylococcus,Weissella,and Tetragenococcus were dominant in the high-salt groups.Higher total free amino acids and essential amino acids,organic acids,hexanoic acid ethyl ester and octanoic acid ethyl ester were found in the low-salt groups.The RDA analysis revealed that Lactococcus was closely related to product quality,with the S3F10(3%salt and 10%rice f lour)group outperforming the others in the sensory evaluation.Therefore,3%salt and 10%rice flour were considered more appropriate for the production of healthy and tasty fermented sour meats.

Changes of growth-climate relationships of Smith fir forests along an altitudinal gradient

Temporal changes in the relationship between tree growth and climate have been observed in numerous forests across the world.The patterns and the possible regu-lators(e.g.,forest community structure)of such changes are,however,not well understood.A vegetation survey and analyses of growth-climate relationships for Abies georgei var.Smithii(Smith fir)forests were carried along an altitudi-nal gradient from 3600 to 4200 m on Meili Snow Mountain,southeastern Tibetan Plateau.The results showed that the associations between growth and temperature have declined since the 1970s over the whole transect,while response to standardized precipitation-evapotranspiration indices(SPEI)strengthened in the mid-and lower-transect.Comparison between growth and vegetation data showed that tree growth was more sensitive to drought in stands with higher species richness and greater shrub cover.Drought stress on growth may be increased by heavy competition from shrub and herb layers.These results show the non-stationary nature of tree growth-climate associations and the linkage to for-est community structures.Vegetation components should be considered in future modeling and forecasting of forest dynamics in relation to climate changes.

Hydrochemical characteristics and the ecological effect of algal carbonic anhydrase in carbon cycle in the Taiyuan section of Fenhe River

Water scarcity and pollution pose a threat to the sustainable development of cities and society.Therefore,it is crucial to analyze the hydrochemical characteristics and carbon dynamics of waterdeficient areas.Taking the Taiyuan section of Fenhe River as the research object,we systematically explored the hydrochemical characteristics of surface water and its evolutionary processes,as well as the ecological effect of algal carbonic anhydrase in carbon cycle using the hydrochemical evolution method and correlation analysis.The ternary diagram demonstrates that the main water chemical type in Fenhe River was SO^(2-)_(4)·Cl^(-)-Na^(+).The Gibbs and end-member diagrams of each ion display that the chemical composition of surface water was mainly controlled by silicate decomposition.The chemical ions originated mainly from dissolution of some minerals,such as plagioclase,halite,dolomite,calcite,and gypsum.The diatoms had a lower CO_(2)requirement because they exhibited a higher abundance at a lower partial pressure of CO_(2)(p CO_(2)).However,high CO_(2)concentration had a positive effect on cyanobacteria,which reduced the active transport of HCO_(3)^(-),saved the energy needed for this part of active transport,and indirectly improved the overall photosynthetic efficiency of algae.Carbonic anhydrase(CA)activity was significantly negatively correlated with p CO_(2)and positively correlated with HCO_(3)^(-)concentration,indicating that CA in water promoted the conversion of CO_(2)to HCO_(3)^(-).The HCO_(3)^(-)generated from this process continued to participate in the erosion of silicate rocks,sequestering CO_(2)in the form of Ca CO_(3),which has a non-negligible impact on the carbon sink in the Fenhe River.These consequences may have important implications for the biogeochemical cycling occurring in urban water.

Structural identification and antioxidative activity evaluation of flaxseed lignan macromolecules: structure-activity correlation

Flaxseed lignan macromolecules(FLM)are a class of important secondary metabolites in fl axseed,which have been widely concerned due to their biological and pharmacological properties,especially for their antioxidative activity.For the composition and structure of FLM,our results confirmed that ferulic acid glycoside(FerAG)was directly ester-linked with herbacetin diglucoside(HDG)or pinoresinol diglucoside(PDG),which might determine the beginning of FLM biosynthesis.Additionally,p-coumaric acid glycoside(CouAG)might determine the end of chain extension during FLM synthesis in fl axseed.FLM exhibited higher antioxidative activity in polar systems,as shown by its superior 1,1-diphenyl-2-picrylhydrazyl(DPPH)free radical scavenging capacity compared to the 2,2’-azinobis(3-ehtylbenzothiazolin-6-sulfnic acid)(ABTS)cation free radical scavenging capacity in non-polar systems.Moreover,the antioxidative activity of FLM was found to be highly dependent on its composition and structure.In particular,it was positively correlated with the number of phenolic hydroxyl groups(longer FLM chains)and inversely related to the steric hindrance at the ends(lower levels of FerAG and CouAG).These fi ndings verifi ed the potential application of FLM in nonpolar systems,particularly in functional food emulsions。

AAV mediated carboxyl terminus of Hsp70 interacting protein overexpression mitigates the cognitive and pathological phenotypes of APP/PS1 mice

The E3 ubiquitin ligase,carboxyl terminus of heat shock protein 70(Hsp70)interacting protein(CHIP),also functions as a co-chaperone and plays a crucial role in the protein quality control system.In this study,we aimed to investigate the neuroprotective effect of overexpressed CHIP on Alzheimer’s disease.We used an adeno-associated virus vector that can cross the blood-brain barrier to mediate CHIP overexpression in APP/PS1 mouse brain.CHIP overexpression significantly ameliorated the performance of APP/PS1 mice in the Morris water maze and nest building tests,reduced amyloid-βplaques,and decreased the expression of both amyloid-βand phosphorylated tau.CHIP also alleviated the concentration of microglia and astrocytes around plaques.In APP/PS1 mice of a younger age,CHIP overexpression promoted an increase in ADAM10 expression and inhibitedβ-site APP cleaving enzyme 1,insulin degrading enzyme,and neprilysin expression.Levels of HSP70 and HSP40,which have functional relevance to CHIP,were also increased.Single nuclei transcriptome sequencing in the hippocampus of CHIP overexpressed mice showed that the lysosomal pathway and oligodendrocyte-related biological processes were up-regulated,which may also reflect a potential mechanism for the neuroprotective effect of CHIP.Our research shows that CHIP effectively reduces the behavior and pathological manifestations of APP/PS1 mice.Indeed,overexpression of CHIP could be a beneficial approach for the treatment of Alzheimer’s disease.

稳定表达PRRSV M蛋白的MARC-145^(ORF6)细胞系的构建及其对PRRSV增殖的影响

为了给深入研究猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndromevirus,PRRSV)ORF6基因编码的M蛋白的生物学功能提供重要试验材料,本研究首先利用慢病毒包装系统构建了过表达PRRSVORF6基因的重组慢病毒质粒,将该质粒连同辅助质粒共同转染至HEK293T细胞获得重组慢病毒;之后将重组慢病毒感染MARC-145细胞,利用嘌呤霉素结合有限稀释法进行筛选,连续筛选3轮后建立了稳定表达PRRSVM蛋白的MARC-145ORF6细胞系;并使用CCK-8试验评估过表达PRRSVM蛋白对MARC-145细胞生长的影响。利用RT-PCR、蛋白免疫印迹(Westernblot)和间接免疫荧光(IFA)评估MARC-145ORF6细胞系的传代稳定性并鉴定M蛋白的亚细胞定位,进一步利用RT-qPCR评估过表达M蛋白对MARC-145细胞的干扰素及相关调节基因的影响;此外,还测定了PRRSV在MARC-145ORF6细胞系、MARC-145Flag细胞系和MARC-145细胞中的病毒滴度并绘制多步生长曲线以比较其差异。CCK-8试验结果表明,过表达PRRSVM蛋白对MARC-145细胞活力无显著影响;RT-qPCR、Westernblot和IFA等试验结果表明,MARC-145ORF6细胞系能够表达PRRSV的M蛋白且在传代过程中稳定。此外,稳定表达PRRSVM蛋白显著下调了细胞系的Ⅰ型干扰素及其相关调节基因;多步生长曲线表明,MARC-145ORF6细胞系促进PRRSV增殖,提高其病毒滴度。综上,本研究构建了可以稳定表达PRRSVM蛋白的MARC-145ORF6细胞系,发现其Ⅰ型干扰素水平显著下调且促进PRRSV复制。本研究构建的MARC-145ORF6细胞系将为M蛋白功能的深入研究提供重要生物材料。

Origin of the presence/absence variation of the LTIA1/LTIA2 mini-ribonucleaseⅢgenes required for low-temperature growth in rice

A rice low temperature-induced albino variant was determined by the recessive ltia1 and ltia2 genes.LTIA1 and LTIA2 encode highly conserved mini-ribonucleasesⅢlocated in chloroplasts and expressed in aerial parts of the plant.At low temperature,LTIA1 and LTIA2 redundantly affect chlorophyll levels,non-photochemical quenching,photosynthetic quantum yield of PSⅡand seedling growth.LTIA1 and LTIA2 proteins are involved in splicing of atp F and the biogenesis of 16S and 23S rRNA in chloroplasts.Presence/absence variation of LTIA1,the ancestral copy,was found only in japonica but that of LTIA2 in all rice subgroups.Accessions with LTIA2 presence tended to be distributed more remote from the equator compared to those with LTIA2 absence.LTIA2 duplicated from LTIA1 at the early stage of divergence of the AA genome Oryza species but deleted againin O.nivara.In cultivated rice,absence of LTIA2 is derived from O.nivara.LTIA1 absence occurred more recently in japonica.