Identification of tRNA-derived Fragments and Their Potential Roles in Atherosclerosis

Objective Atherosclerosis(AS),a chronic inflammatory disease,is the basis of cardiovascular disease(CVD).Although the treatment has been greatly improved,AS still imposes a large burden on human health and the medical system,and we still need to further study its pathogenesis.As a novel biomolecule,transfer RNA-derived fragments(tRFs)play a key role in the progression of various disease.However,whether tRFs contribute to atherosclerosis pathogenesis remains unexplored.Methods With deep sequencing technology,the change of tRFs expression profiles in patients with AS compared to healthy control group was identified.The accuracy of the sequencing data was validated using RT qPCR.Subsequently,we predicted the potential target genes of tRFs by online miRNA target prediction algorithms.The potential functions of tRFs were evaluated with Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analyses.Results There were 13 tRFs differentially expressed between patients with AS and healthy controls,of which 2 were up-regulated and 11 were down-regulated.Validation by RT-qPCR analysis confirmed the sequencing results,and tRF-Gly-GCC-009 was highly up-regulated in the AS group based on the results of sequencing which was confirmed by RT-qPCR analysis.Furthermore,GO enrichment and KEGG pathway analyses indicated that 10 signaling pathways were related to tRF-Gly-GCC-009.These pathways might be physiopathological fundamentals of AS,mainly involving in Apelin signaling,Notch signaling and calcium signaling.Conclusion The results of our study provide important novel insight into the underlying pathogenesis and demonstrate that tRFs might be potential biomarkers and therapeutic targets for AS in the future.

Genome-wide interrogation of transfer RNA-derived small RNAs in a mouse model of traumatic brain injury

Transfer RNA(t RNA)-derived small RNAs(ts RNAs) are a recently established family of regulatory small non-coding RNAs that modulate diverse biological processes. Growing evidence indicates that ts RNAs are involved in neurological disorders and play a role in the pathogenesis of neurodegenerative disease. However, whether ts RNAs are involved in traumatic brain injury-induced secondary injury remains poorly understood. In this study, a mouse controlled cortical impact model of traumatic brain injury was established, and integrated ts RNA and messenger RNA(m RNA) transcriptome sequencing were used. The results revealed that 103 ts RNAs were differentially expressed in the mouse model of traumatic brain injury at 72 hours, of which 56 ts RNAs were upregulated and 47 ts RNAs were downregulated. Based on micro RNA-like seed matching and Pearson correlation analysis, 57 differentially expressed ts RNA-m RNA interaction pairs were identified, including 29 ts RNAs and 26 m RNAs. Moreover, Gene Ontology annotation of target genes revealed that the significantly enriched terms were primarily associated with inflammation and synaptic function. Collectively, our findings suggest that ts RNAs may be associated with traumatic brain injury-induced secondary brain injury, and are thus a potential therapeutic target for traumatic brain injury. The study was approved by the Beijing Neurosurgical Institute Animal Care and Use Committee(approval No. 20190411) on April 11, 2019.

Sperm DNA fragmentation does not affect the clinical outcomes in the cumulative transfers of an ICSI cycle along with blastocyst transfers in couples with normozoospermic male patients

Objective:To know whether sperm DNA fragmentation(SDF)affects the clinical outcomes in the cumulative transfers of an intracytoplasmic sperm injection(ICSI)cycle along with blastocyst transfers in couples with normozoospermic males.Methods:The study included 252 couples who underwent their first ICSI cycles along with blastocyst transfer and whose male partner semen samples were normozoospermic according to the World Health Organization 2010 criteria.All the couples were classified into two groups based on the SDF:the low SDF group(SDF≤30%,n=162)and the high SDF group(SDF>30%,n=90).Clinical as well as laboratory outcomes were correlated between the two groups.Sperm DNA fragmentation was assessed on the post-wash semen samples by acridine orange test.The main outcome measures were the live birth rate and miscarriage rate.Results:A significant decrease in the live birth rates was observed in the high SDF group compared to the low SDF group in fresh embryo transfer cycles(P<0.05).However,no significant difference was observed in the clinical outcomes either in the frozen embryo transfer cycles or in the overall cumulative transfer cycles(P>0.05).No significant difference was observed in the laboratory outcomes between the two SDF groups.A remarkable decrease in sperm motility was observed in the high SDF group compared to the low SDF group(P<0.05).Conclusions:Sperm DNA fragmentation does not affect the clinical outcomes in the cumulative transfers of an ICSI cycle along with blastocyst transfers in couples with normozoospermic males.

The reversible addition-fragmentation chain transfer(RAFT) miniemulsion polymerization of vinyl acetate mediated by xanthate

The reversible addition-fragmentation chain transfer （RAFT） miniemulsion polymerization of vinyl acetate （VAc） mediated by methyl （methoxycarbonothioyl） sulfanyl acetate （MMSA） was carried out. The results showed that polymerizations initiated by AIBN and KPS proceeded in a controlled way. The RAFT miniemulsion polymerization of VAc initiated by KPS showed the shorter inhibition period, higher propagation rate coefficient and final conversion than those in experiment initiated by AIBN. When the monomer conversion reached 25%, the polydispersity index （PDI） of polymer became broad, which was related to chain transfer reaction in RAFT miniemulsion of VAc.

Synthesis of polystyrene-styrene/butadiene diblock copolymers via reversible addition-fragmentation chain transfer miniemulsion polymerization

Polystyrene-styrene/butadiene diblock copolymers were synthesized via reversible addition-fragmentation chain transfer （RAFT） miniemulsion polymerization.During the polymerization process,the molecular weight distribution was narrow and the numerical molecular weight of the copolymers increased with increasing conversion of monomers,which was close to the theoretical.FT-IR and ^1H NMR results indicated that the microstructure of the polymer was mainly 1,4-trans-butadiene with small amount of 1,2-units,and composition in the copolymers was obtained.

Reversible addition-fragmentation chain transfer graft polymerization of acrylonitrile onto PE/PET composite fiber initiated by γ-irradiation

Reversible addition-fragmentation chain transfer(RAFT) mediated grafting of acrylonitrile onto Polyethylene/Poly(ethylene terephthalate)(PE/PET) composite fibers was performed using γ-irradiation as the initial source at ambient temperature. Different initial concentrations of 2-cyanoprop-2-yl dithiobenzonate were used as the chain transfer agent. The kinetics of graft polymerization is in accordance with the living RAFT polymerization. The successful grafting of acrylonitrile is proved by Fourier transform infrared spectroscopy analysis.The results of monofilament tensile test show that mechanical properties of the fibers change slightly after grafting. Scanning electronic microscopy images of the fibers show that the surface of RAFT grafted fibers is smoother than that of fibers grafted conventionally.

Evaluation of the clenbuterol imprinted monolithic column prepared by reversible addition-fragmentation chain transfer polymerization

To make more homogenous organic monolithic structure, reversible addition-fragmentation chain transfer （RAFT） process was employed in the synthesis of the clenbuterol imprinted polymer. In the synthesis, the influence of synthetic conditions on the polymer structure and separation efficiency was studied. The result demonstrated that the imprinted columns prepared with RAFT process have higher column efficiency and selectivity than the columns prepared with conventional polymerization in the present study, which may result from the higher surface area, smaller pore size and the narrower globule size distribution in their structures. The result indicated that RAFT polymerization provided better conditions for the clenbuterol imprinted monolithic polymer preparation. 2009 Xiang Chao Dong. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

The biogenesis and biological roles of tRNA-derived short RNAs

In recent years, next-generation sequencing (NGS) technologies targeting the microRNA (miRNA)transcriptome revealed the existence of tRNA-derived short RNAs: tRNA halves (tiRNAs) and tRNA-derived fragments (tRFs). These small RNAs represent a novel type of small non-coding RNAs (sncRNAs), which are heterogeneous in size, nucleotide composition and biogenesis, and have been suggested to be involved in translation, cell proliferation, priming of viral reverse transcriptases, regulation of gene expression, modulation of the DNA damage response, tumor suppression and neurological disorders. Herein, we review the mechanism of their biogenesis and discuss in detail the regulatory roles they play in cell physiology. We also point out that the biological function of tRNA-derived short RNAs will be understood better as research moves forward, and that this knowledge will find its way into clinical application in the near future.

血清NSE、CYFRA21-1及Pro-GRP与肺癌病理特征及转移的关系

目的探讨血清神经元特异性烯醇化酶(NSE)、细胞角蛋白19片段(CYFRA21-1)及胃泌素释放肽前体(Pro-GRP)与肺癌病理特征及转移的关系。方法选择100例肺癌患者设为肺癌组,50例肺部良性病变患者设为良性组和50例健康体检者设为对照组,采集3组受检者空腹静脉血5 mL,测定血清NSE、Pro-GRP、CYFRA21-1水平。对比3组NSE、Pro-GRP、CYFRA21-1水平差异,并分析NSE、Pro-GRP、CYFRA21-1与肺癌病理特征及转移的关系。结果肺癌组、良性组NSE、Pro-GRP、CYFRA21-1水平均高于对照组,有统计学差异(P<0.05)。肺癌Ⅲ~Ⅳ期者NSE、Pro-GRP、CYFRA21-1水平高于Ⅰ~Ⅱ期者,有统计学差异(P<0.05);小细胞癌NSE、Pro-GRP水平高于腺癌、鳞癌,CYFRA21-1水平低于腺癌,鳞癌Pro-GRP水平高于腺癌,CYFRA21-1水平低于腺癌,有统计学差异(P<0.05);有转移者NSE、Pro-GRP、CYFRA21-1水平均高于无转移者,有统计学差异(P<0.05)。结论肺癌患者NSE、Pro-GRP、CYFRA21-1呈高表达,其水平高低与TNM分期和转移有关。

精子DNA碎片对体外受精-胚胎移植妊娠结局及胚胎发育的影响

目的:分析精子DNA碎片指数(DFI)对体外受精-新鲜胚胎移植(IVF-ET)助孕及活产结局的影响。方法:选取2015年6月至2020年12月因女方因素首次行IVF并进行新鲜胚胎移植的患者共947例,根据DFI分为低、中、高3组:DFI<15%、15≤DFI≤30%和30%<DFI,比较3组双方基础数据,女方包括年龄、体质量指数(BMI)、基础生殖激素、AMH等;男方包括年龄、BMI、精液参数;超促排卵参数;处理前和处理后IVF精液参数;促排卵结局、胚胎质量及妊娠结局。结果:不同DFI水平间相比,双方年龄在3组间均有显著性差异,15≤DFI≤30%和30%<DFI组双方年龄显著大于DFI<15%组;基础状态精液参数中前向运动精子百分率、非前向运动精子百分率、不活动精子百分率,以及IVF处理前精子总活率、前向运动精子百分率在3组间也均有显著差异(P<0.01);中和高DFI组中基础精子正常形态率、IVF处理前精子浓度、精子总数和处理后精子浓度均显著低于低DFI组;30%<DFI组无论是精液处理前还是精液处理后精子总数均显著低于其他两组(P<0.01)。此外,中和高DFI组受精率显著低于低DFI组,其他临床数据包括促排卵参数、胚胎质量、妊娠结局组间均无显著差异。结论:高DFI水平对精子活率产生显著影响,IVF精液处理后DFI水平与精子浓度、精子总数、受精率均呈显著负相关,对胚胎质量及妊娠结局无影响。

聚羧酸保坍剂分子序列结构对其性能的影响

通过普通自由基聚合合成侧链密度不同的无规序列结构聚羧酸保坍剂PCE-1、PCE-2;通过可逆加成-碎裂链转移聚合(RAFT)合成侧链在主链上分布形式分别为“外密内疏”和“外疏内密”梯度序列结构的聚羧酸保坍剂PCE-3、PCE-4。通过凝胶渗透色谱仪(GPC)测试证明PCE-3、PCE-4的分子质量与转化率呈线性关系,符合“活性”聚合特征。净浆和混凝土试验发现,各减水剂分散性能排序为PCE-4<PCE-1<PCE-2<PCE-3,即“外密内疏”的序列结构最适合发挥PCE的分散性,而“外疏内密”不适合作为PCE的结构。含蒙脱土的净浆试验表明,具有“紧密”侧链序列的PCE-1、PCE-3有着更好的抗泥效果。吸附试验表明,吸附能力排序为PCE-4<PCE-3<PCE-1≈PCE-2。

原子核内结团结构研究的探测器设置

原子核结团结构是目前核物理研究的热点之一,其常用的实验测量方法有碎裂反应和转移反应2种,然而如何摆放实验中的探测器以获得最佳的探测效率和能量分辨,目前还有待科学地分析研究.首先对原子核的激发过程进行了分析,为反应后碎片的如何分布提供了理论基础;然后根据不同激发过程对碎片分布的影响进行了系统模拟研究,仔细分析了探测器与靶的距离对探测效率和能量分辨的影响;最后与已开展的实验进行了对比研究,给出了现有实验装置测量时的改进方法,该方法可对后续的实验设置进行计算优化,并对类似的实验设置进行指导.

tRNA衍生片段(tRFs)调节基因表达的机制及其在相关疾病中的研究进展

转运RNA(transfer RNA,tRNA)衍生片段(tRNA-derived fragments,tRFs)是一类新的调节性非编码RNA,在应激诱导的疾病和癌症中具有独特的生物学功能。细胞必须合成新的蛋白质来维持其寿命,而tRNAs是蛋白质翻译过程的重要组成部分。成熟tRNAs和前体tRNAs根据不同的酶切位点被裂解为两种类型:tRNA半体(tiRNAs,长度为28~36 nt)和tRFs(长度为14~30 nt)。前者包含2个亚类:5′-tiRNAs和3′-tiRNAs,后者分为5个亚类:tRF-1、tRF-2、tRF-3、tRF-5和i-tRF。tRFs通过与其他类型的RNA或蛋白质相互作用来调节基因的表达,并在多种疾病中异常表达,如在神经退行性病变、病毒感染等多种疾病中发挥重要作用,且在胃癌、肝癌等多种癌症中异常表达。本文就tRFs在人类疾病中的研究进展进行综述。

促进还是抑制:土地互换制度是如何影响土地流转的

对土地互换制度如何影响土地流转的回答是构建适度规模经营与小农户并行路径、优化小农内生发展的基础。研究利用山东省和安徽省调研得到的232个村庄数据和826份农户数据,采用Tobit和SNP模型分析了土地互换制度对土地流转的影响,利用逆概率加权IPW模型对选择性偏差进行控制,以尝试对土地互换制度与土地流转间的关系进行回答。研究发现:土地互换制度抑制了农户转出土地,增加了农户流入农地的需求;相较于规模户,土地互换对扩大小农户经营地面积有更强的促进作用,推动小农户内生发展。在村庄层面上,土地互换制度促进了村庄的土地流转,并且村庄的平均土地流转费用增加。实现土地规模经营、农户与村集体“收入双增”、有效利用土地资源可以将土地互换制度作为突破口。

转运RNA衍生的小RNA研究概述

转运RNA(tRNA)衍生的小RNA(tsRNAs)是由成熟tRNA或前体tRNA在应激条件下经特定核酸酶切割后所产生的一类小非编码RNA,具有高保守性、组织特异性和疾病相关性等特点,可作为生物标志物及治疗靶点。本文从tsRNAs的发现、分类、生物学功能及其在疾病中的作用等方面对其研究现状进行综述,以期为表观遗传学相关内容的教学提供参考信息。

转运RNA衍生片段15:31对TGF-β_(1)诱导的小鼠肾小球系膜细胞增殖和炎症反应的影响

目的 观察转运RNA衍生片段15:31-Arg-CCT-3-1(tRF-15:31)对转化生长因子β_(1)(TGF-β_(1))诱导的小鼠肾小球系膜细胞增殖和炎症反应的影响。方法 体外培养小鼠肾小球系膜细胞,将细胞分为tRF组、NC组、模型组和对照组。对照组使用正常糖培养基培养细胞。tRF组、NC组、模型组以含10 ng/mL TGF-β_(1)的培养基培养24 h诱导CKD细胞模型;tRF组、NC组分别转染tRF-15:31 mimic和阴性对照。各组干预24 h后,采用CCK-8试剂盒检测细胞增殖能力,采用Western blotting法检测各组细胞中的纤维化指标[纤维连接蛋白(FN)、Ⅰ型胶原蛋白(ColⅠ)、α平滑肌肌动蛋白(α-SMA)]和炎症指标[白细胞介素6(IL-6)、肿瘤坏死因子α(TNF-α)]蛋白,采用逆转录定量PCR法检测FN、ColⅠ、α-SMA、IL-6、TNF-α mRNA,采用ELISA法检测各组细胞培养液上清中的IL-6、TNF-α。结果模型组增殖活力高于对照组,模型组FN、ColⅠ、α-SMA、IL-6、TNF-α蛋白及mRNA表达和培养液上清中IL-6、TNF-α水平高于对照组(P均<0.05);tRF组增殖活力低于NC组,tRF组FN、ColⅠ、α-SMA、IL-6、TNF-α蛋白及mRNA表达和培养液上清中IL-6、TNF-α水平低于NC组(P均<0.05)。结论 tRF-15:31可抑制TGF-β_(1)诱导的小鼠肾小球系膜细胞增殖,并减少炎症因子分泌。

基于活产建立体外受精-胚胎移植精子DNA碎片指数的参考阈值及子代短期安全性

背景:精子DNA碎片指数与受精、胚胎发育潜能、胚胎植入、流产及子代安全性等存在显著的相关性。然而,其临床参考值受多种因素的影响,导致临床意义极其有限,该研究以活产为结局,通过倾向评分匹配校正其他混杂因素后,构建精子DNA碎片指数与活产的最佳临床截断值,并对其进行内外部验证,具有较好的预测价值及临床应用效能。目的:探讨基于活产建立体外受精-胚胎移植精子DNA碎片指数的参考阈值及子代短期安全性。方法:选取2019年5月至2021年5月于常州市妇幼保健院接受体外受精-胚胎移植患者1921例,以倾向匹配容差0.02为标准,1∶1进行倾向评分匹配,结果活产组与非活产组各成功匹配540例,以此建立模型组;通过选取同时期广西壮族自治区南溪山医院接受体外受精-胚胎移植患者135例作为外部验证组;采用受试者工作曲线探求精子DNA碎片指数对活产的临床最佳截断值,分别采用限制性立方样条曲线、标准曲线、临床决策曲线、临床影响曲线及内外部验证等方法,对该截断值的准确性及临床应用效能进行评估。结果与结论:(1)非活产组精子DNA碎片指数显著高于活产组且与活产存在显著的负相关性(r=-0.444,P<0.001);(2)受试者工作曲线结果显示,DNA碎片指数对活产的最佳截断值为24.33%,曲线下面积为0.775(0.746,0.804),特异度为72.60%,敏感度为78.90%,准确度为75.70%;(3)限制性立方样条曲线拟合Logistic回归结果显示,当精子DNA碎片指数大于24.57%时,临床非活产的风险呈趋势性增涨;(4)Logistic回归概率分析结果显示,精子DNA碎片指数为活产的危险因素[OR(95%CI)=0.916(0.904,0.928),P<0.001],且当精子DNA碎片指数大于27.78%时,临床活产发生的概率将小于50%,随着精子DNA碎片指数每增高1个单位,活产的概率下降8.4%;(5)内外部对该临床截断值的验证均显示,该截点具有一定的临床预测价值及准确性;(6)临床决策曲线与临床影响曲线显示,以该临床截断值建立的预测模型在阈概率为0.22-0.73时具有临床最大净获益值,且在该阈概率范围内损失与获益的比值始终小于1,证实该预测模型具有较好的临床应用效能;(7)精子DNA碎片指数与子代短期安全性分析结果显示,精子DNA碎片指数与出生儿早产、体质量、畸形、性别差异无显著性;(8)结果表明,精子DNA碎片指数对体外受精-胚胎移植活产的最佳临床截断值为24.33%,以此建立的临床预测模型具有较好的区分度、准确度与临床应用效能,精子DNA碎片指数对子代短期安全性影响并不显著,但仍需大样本及长期的追踪评估。

耕地细碎化对农户种植业收入的影响——“非粮化”和耕地流转率的调节效应

耕地细碎化会导致农户种植活动的分散化,减少了农户的有效劳动时间,并阻碍了机械化作业的开展,不利于种植业的增产增收。采用“全国农村固定观察点调查”2009—2020年的面板数据,以种植主导型农户为研究样本,分析发现:农户的耕地细碎化程度提高对其种植业收入具有显著的负向影响,该结论在经过一系列稳健性检验和内生性处理后依然成立;家庭种植结构“非粮化”和村庄耕地流转率提高可以显著弱化耕地细碎化对农户种植业收入增长的抑制作用;相对而言,耕地细碎化对化肥施用强度较高农户、老龄化程度较高农户、丘陵山区农户的种植业收入具有更强的负向影响。因此,应促进耕地流转市场发育,加强农村土地整治,提高粮食生产比较收益,推动化肥农药使用减量增效,拓展优化农业社会化服务,在降低农户耕地细碎化程度的同时,有效缓解耕地细碎化对农民收入增长的抑制作用。

基于光引发可逆加成断裂链转移自由基聚合的3D打印

针对高分子化学本科教学中“活性自由基聚合”知识点抽象,学生难以理解的教学难题,开展了光引发可逆加成断裂链转移(RAFT)自由基聚合3D打印实验。实验首先合成O-(乙基)-S-(2-丙酸乙酯基)黄原酸酯(EXEP),随后使用商用光敏树脂,进行添加/不添加EXEP条件下的3D打印。随后使用得到的打印体开展荧光功能后修饰与焊接对比实验。通过对比实验现象,深入理解活性自由基聚合机理及其对产物后功能化能力的影响,实现“活性自由基聚合”原理的“可视化”和实例化应用展示。本实验将基础理论有机融合到趣味实验中,实验耗时合理,操作简便,效果明显,符合本科教学实验基本要求,有助于提升学生综合分析能力,激发学生深入研究的兴趣,培养其创新意识及拓展延伸的能力。

甲基丙烯酸甲酯可逆加成-断裂链转移聚合动力学研究

通过可逆加成-断裂链转移(RAFT)溶液聚合制得一系列分子量可控、分子量分布窄的聚甲基丙烯酸甲酯(PMMA),考察了反应条件对聚合速率、PMMA分子量及其分布的影响。实验结果表明,溶剂质量、聚合温度和引发剂浓度是影响聚合速率的主要因素,而RAFT试剂浓度和结构可调控PMMA的分子量及其分布。对于甲基丙烯酸甲酯体系,密度泛函理论的计算结果表明,RAFT试剂“激活”过程的Gibbs自由能变(ΔG)是评估RAFT试剂对聚合物分子量分布控制效果的关键因素。ΔG越小,表明RAFT试剂越容易被“激活”,控制效果越好。提出了一种快速判断RAFT试剂可行性的理论计算依据,降低了RAFT试剂的实验开发成本。