Chemiluminescence assay for kanamycin based on target recycling strategy

A chemiluminescence (CL) sensing strategy for kanamycin residue detection in fish samples was established based on luminol-functionalized gold nanoparticles as CL nanoprobe materials combined with DNA hairpin structure and carboxyl-modified magnetic beads. Relying on nucleic acid amplification technology, the system can successfully realize the recycling of kanamycin, so that the biosensor can release a large number of luminol-functionalized gold nanoparticles with excellent CL performance even at a low residual levels of kanamycin. The biosensor strategy showed a good linear relationship with kanamycin in the range 0.09–130 nM, the detection limit was as low as 0.04 nM. This method proves the excellent performance of the sensing strategy and provides a low-cost and high-sensitivity CL analysis strategy for the detection of kanamycin and even other antibiotics.     

MDP25 mediates the fine-tuning of microtubule organization in response to salt stress

Microtubules are dynamic cytoskeleton structures playing fundamental roles in plant responses to salt stress. The precise mechanisms by which microtubule organization is regulated under salt stress are largely unknown. Here, we report that Arabidopsis thaliana MICROTUBULE-DESTABILIZING PROTEIN 25 (MDP25; also known as PLASMA MEMBRANE-ASSOCIATED CATION-BINDING PROTEIN 1 (PCaP1)) helps regulate microtubule organization. Under salt treatment, elevated cytosolic Ca²⁺ concentration caused MDP25 to partially dissociate from the plasma membrane, promoting microtubule depolymerization. When Ca²⁺ signaling was blocked by BAPTA-AM or LaCl₃, microtubule depolymerization in wild-type and MDP25-overexpressing cells was slower, while there was no obvious change in mdp25 cells. Knockout of MDP25 improved microtubule reassembly and was conducive to microtubule integrity under long-term salt treatment and microtubule recovery after salt stress. Moreover, mdp25 seedlings exhibited a higher survival rate under salt stress. The presence microtubule-disrupting reagent oryzalin or microtubule-stabilizing reagent paclitaxel differentially affected the survival rates of different genotypes under salt stress. MDP25 promoted microtubule instability by affecting the catastrophe and rescue frequencies, shrinkage rate and time in pause phase at the microtubule plus-end and the depolymerization rate at the microtubule minus-end. These findings reveal a role for MDP25 in regulating microtubule organization under salt treatment by affecting microtubule dynamics.     

两种荒漠豆科植物化学计量特征与生境土壤因子的关系

豆科植物是荒漠等干旱生态系统的重要先锋物种,也是生态系统中有效氮的主要来源。为了明确荒漠豆科植物与生境土壤因子之间的关系,该研究以古尔班通古特沙漠广泛分布的荒漠豆科植物弯花黄芪(Astragalus flexus)、镰荚黄芪(Astragalus arpilobus)为对象,测定不同土壤深度(0~5、5~10、10~15 cm)的理化性质,比较分析2种荒漠豆科植物化学计量特征与土壤因子的关系。结果表明:(1)弯花黄芪碳(C)、氮(N)、磷(P)含量分别为373.35、25.66、1.03 mg·g^-1,高于镰荚黄芪的331.53、19.59、0.66 mg·g^-1,且二者的N、P含量均差异显著(P<0.05);弯花黄芪的C∶P、N∶P分别为374.38、25.75,均极显著高于镰荚黄芪的166.09、10.12(P<0.01),而弯花黄芪的C∶N(14.62)低于镰荚黄芪(16.99),两种植物的C和C∶N均无显著差异。(2)豆科植物生境土壤在0~5 cm土层的有机碳(SOC)、全氮(TN)、全磷(TP)含量最高,且随土层的加深逐渐减少;土壤化学计量比SOC∶TN、SOC∶TP均随土层加深逐渐增大,而TN∶TP值随土层加深逐渐减少;较低的N含量及TN∶TP 显示该区域土壤属于N素缺乏类型。(3)2种荒漠豆科植物与各层次土壤化学计量特征的相关性无一致规律。其中,弯花黄芪立地0~10 cm土层的TN与N∶P间呈负相关关系,TP与P间呈极显著负相关关系,而TP与C∶N间呈正相关关系,SOC∶TN与N∶P间呈极显著正相关关系;在10~15 cm土层中,SOC∶TN与N∶P间呈正相关关系。镰荚黄芪中仅P含量与其立地0~5 cm土层的SOC∶TP具有极显著正相关关系,而大部分化学计量特征间未显示出相关性。(4)弯花黄芪的植物化学计量指标P含量与5~10 cm土层的电导率(EC)间呈极显著正相关关系,N含量与10~15 cm土层的速效钾(AK)间呈正相关关系;而镰荚黄芪N、AP与N∶P与0~5 cm土层的速效磷(AP)间均呈极显著负相关关系,与其他土层未出现相关关系。研究认为,古尔班通古特沙漠土壤N含量以及TN∶TP较低,土壤N元素贫瘠,且该区豆科植物立地土壤养分含量总体偏低;该区弯花黄芪生长的主要限制元素为P,而镰荚黄芪生长的主要限制元素为N和P;植物化学计量特征并非全部由土壤养分特征直接决定,其明显的种间差异显示植物自身遗传特性在土壤 植物计量特征耦合关系的重要性。     

环境变化对水稻osfh1突变体成蛋白家族表达的影响

水稻成蛋白基因成员OsFH1在水稻根毛的生长发育中起着关键作用,这一过程受到环境因素的调控,当前的研究对环境因素如何与OsFH1互作调控水稻根毛的机制尚未阐明。为探索水稻成蛋白成员是否在环境因素介导的osfh1突变体根毛表型恢复中发挥作用,该研究使用1/2 MS液体培养液与1/2 MS固体培养基处理osfh1突变体,通过qRT-PCR技术分析成蛋白家族成员表达量,并对成蛋白家族进行生物信息学分析。结果表明:(1)与野生型相比,在液培中osfh1突变体主根根毛缺失,地上部分较短,侧根数量增加,在固体培养中osfh1突变体根毛缺失表型得到恢复。(2)与野生型相比,当osfh1突变体从液培到固培环境时,OsFH16表达量下降,OsFH17表达量上升,并且差异显著。(3)OsFH1、OsFH16、OsFH17都是第一类成蛋白亚家族成员,都具有生长素、赤霉素以及厌氧等与环境胁迫相关顺式作用元件,并且预测到OsFH1、OsFH16和OsFH17定位于质膜行使功能。(4)OsFHs在不同组织的表达模式分析表明,OsFH1在根部表达水平较高,而OsFH16、OsFH17在根部表达量相对较低。综上认为,由于OsFH16、OsFH17、OsFH1之间亲缘关系较高,调控模式相近且三者都可能在细胞质膜上行使功能,因此OsFH16、OsFH17可能参与环境因素与osfh1共同改变根毛表型这一过程。该研究结果为解析环境与osfh1基因共同调控水稻根毛发育机制奠定了一定理论基础,为探索植物成蛋白基因功能提出了新方向。     

Cdkn2a示踪小鼠:研究创伤性骨关节炎软骨退变细胞衰老的新模型

骨关节炎(osteoarthritis,OA)是临床上最为常见的老年性运动系统疾病之一。研究表明,衰老是OA发生发展的重要影响因素之一,但其具体作用及机制尚未完全清楚。本研究通过CRISPR/Cas9技术,建立了Cdkn2a-e(Luc-2A-tdTomato-2A-CreERT2-WPRE-pA)1定点敲入的杂合子小鼠模型,可在小鼠活体内追踪衰老经典标记物Cdkn2a(p16, p16INK4a)的表达情况,结合前交叉韧带横断术(ACLT)诱导OA小鼠模型,将OA病理进程中的衰老变化在体外直观呈现,明确衰老与OA之间的关系。本研究选取10 ～ 12周龄Cdkn2a小鼠,随机分为非手术对照组、假手术组和ACLT组,通过ACLT手术在小鼠中构建OA的模型,术后4周收取动物进行活体荧光成像检测显示,ACLT组术后4周的小鼠膝关节局部Cdkn2a荧光表达升高(P＜0.05),小鼠膝关节组织切片的番红O固绿染色显示,4周时ACLT组膝关节软骨出现退变(P＜0.05),对小鼠膝关节组织进行Cdkn2a免疫组织化学染色,相较其他2个组,ACLT组的小鼠膝关节组织软骨表面Cdkn2a染色更深。研究结果显示,通过手术诱导的OA模型在局部具有衰老的表现,这进一步验证了衰老和OA的关系。同时,该Cdkn2a示踪小鼠模型能够在活体小鼠内体现衰老的进展。结合影像学检查,可以实时观察衰老和OA发生、进展的关系,为衰老与OA疾病机制的研究提供了良好的模型,也为今后进行靶向衰老进行OA的治疗提供了很好的研究工具。     

小分子药物BNTA通过上调Insig1缓解高胆固醇引起的骨关节炎

骨关节炎(osteoarthritis,OA)是运动系统常见的退行性疾病,具有高发病率和高致残率。骨关节炎的发病机制目前尚不明确,既往研究认为骨关节炎发病主要与创伤因素相关,而近期研究表明,以胆固醇代谢异常为主的代谢性因素同样与骨关节炎密切相关,骨关节炎的治疗以早期对症治疗和晚期手术治疗为主,尚无针对病因的特效药物。既往研究中发现,有一种具有软骨保护作用的小分子药物BNTA,其在创伤引起的骨关节炎中具有较好的疗效,但其对高胆固醇引起的骨关节炎的作用尚不明确。本研究为探究BNTA对高胆固醇引起的骨关节炎的治疗作用及其机制,采用高胆固醇饮食构建了大鼠骨关节炎模型,取膝关节石蜡切片进行组织学评估,使用油红O染色评估大鼠软骨细胞内的脂质积聚情况,使用RT-qPCR、免疫荧光和免疫组化评估软骨细胞合成代谢、分解代谢及胆固醇代谢相关基因和蛋白质的表达。结果显示,BNTA可缓解高胆固醇大鼠骨关节炎模型中的病理表现,改善OARSI评分。在大鼠软骨细胞中,BNTA可促进合成代谢相关基因col2、sox9、acan的表达,抑制分解代谢相关基因mmp13、adamts5的表达,可改善高胆固醇引起的大鼠软骨细胞脂质积聚。在大鼠软骨细胞和高胆固醇大鼠骨关节炎模型中BNTA均可上调Insig1表达。本研究证实,高胆固醇可在体内和体外实验中加重骨关节炎,可引起大鼠软骨细胞脂质积聚增加。在体内和体外实验中BNTA均能缓解高胆固醇引起的骨关节炎表型,改善软骨细胞内的异常脂质积聚,其作用可能为通过上调Insig1抑制细胞内的胆固醇生物合成,从而缓解脂质异常积聚。     

Design,Synthesis, and Biological Evaluation of a Novel Series of Pirfenidone Derivatives

Russian Journal of Bioorganic Chemistry - In this study, a series of novel pirfenidone derivatives were designed and synthesized, and their activities against pulmonary fibrosis were evaluated. The...     

Homoplasy or plesiomorphy? Reconstruction of the evolutionary history of mitochondrial gene order rearrangements in the subphylum Neodermata

Recent mitogenomic studies have exposed a gene order (GO) shared by two classes, four orders and 31 species (‘common GO’) within the flatworm subphylum Neodermata. There are two possible hypotheses for this phenomenon: convergent evolution (homoplasy) or shared ancestry (plesiomorphy). To test those, we conducted a meta-analysis on all available mitogenomes to infer the evolutionary history of GO in Neodermata. To improve the resolution, we added a newly sequenced mitogenome that exhibited the common GO, Euryhaliotrema johni (Ancyrocephalinae), to the dataset. Phylogenetic analyses conducted on two datasets (nucleotides of all 36 genes and amino acid sequences of 12 protein coding genes) and four algorithms (MrBayes, RAxML, IQ-TREE and PhyloBayes) produced topology instability towards the tips, so ancestral GO reconstructions were conducted using TreeREx and MLGO programs using all eight obtained topologies, plus three unique topologies from previous studies. The results consistently supported the second hypothesis, resolving the common GO as a plesiomorphic ancestral GO for Neodermata, Cestoda, Monopisthocotylea, Cestoda + Trematoda and Cestoda + Trematoda + Monopisthocotylea. This allowed us to trace the evolutionary GO scenarios from each common ancestor to its descendants amongst the Monogenea and Cestoda classes, and propose that the common GO was most likely retained throughout all of the common ancestors, leading to the extant species possessing the common GO. Neodermatan phylogeny inferred from GOs was largely incongruent with all 11 topologies described above, but it did support the mitogenomic dataset in resolving Polyopisthocotylea as the earliest neodermatan branch. Although highly derived GOs might be of some use in resolving isolated taxonomic and phylogenetic uncertainties, we conclude that, due to the discontinuous nature of their evolution, they tend to produce artefactual phylogenetic relationships, which makes them unsuitable for phylogenetic reconstruction in Neodermata. Wider and denser sampling of neodermatan mitogenomic sequences will be needed to infer the evolutionary pathways leading to the observed diversity of GOs with confidence.     

BI1 alleviates cardiac microvascular ischemia-reperfusion injury via modifying mitochondrial fission and inhibiting XO/ROS/F-actin pathways

Pathogenesis of cardiac microvascular ischemia-reperfusion (IR) injury is associated with excessive mitochondrial fission. However, the upstream mediator of mitochondrial fission remains obscure. Bax inhibitor 1 (BI1) is linked to multiple mitochondrial functions, and there have been no studies investigating the contribution of BI1 on mitochondrial fission in the setting of cardiac microvascular IR injury. This study was undertaken to establish the action of BI1 on the cardiac microvascular reperfusion injury and figure out whether BI1 sustained endothelial viability via inhibiting mitochondrial fission. Our observation indicated that BI1 was downregulated in reperfused hearts and overexpression of BI1 attenuated microvascular IR injury. Mechanistically, reperfusion injury elevated the levels of xanthine oxidase (XO), an effect that was followed by increased reactive oxygen species (ROS) production. Subsequently, oxidative stress mediated F-actin depolymerization and the latter promoted mitochondrial fission. Aberrant fission caused mitochondrial dysfunction and ultimately activated mitochondrial apoptosis in cardiac microvascular endothelial cells. By comparison, BI1 overexpression repressed XO expression and thus neutralized ROS, interrupting F-actin-mediated mitochondrial fission. The inhibitory effect of BI1 on mitochondrial fission sustained endothelial viability, reversed endothelial barrier integrity, attenuated the microvascular inflammation response, and maintained microcirculation patency. Altogether, we conclude that BI1 is essential in maintaining mitochondrial homeostasis and alleviating cardiac microvascular IR injury. Deregulated BI1 via the XO/ROS/F-actin pathways plays a causative role in the development of cardiac microvascular reperfusion injury.