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.     

冠状动脉粥样硬化性心脏病患者血清SFRP5、FGF21、IGF-I水平与血脂和冠状动脉病变严重程度的相关性研究

目的:探讨冠状动脉粥样硬化性心脏病(CHD)患者血清分泌型卷曲蛋白5(SFRP5)、成纤维细胞生长因子21(FGF21)、胰岛素样生长因子-1(IGF-I)水平与血脂和冠状动脉病变严重程度的相关性。方法:选择2018年6月至2021年6月我院收治的109例CHD患者(CHD组),根据冠心病类型分为稳定型心绞痛组(SAP组,32例),不稳定型心绞痛组(UA组,42例)、急性心肌梗死组(AMI组,35例),根据Gensini积分分为轻度病变组(≤20分,42例)、中度病变组(21~40分,44例)和重度病变组(>40分,23例),另选择同期在我院行冠脉造影检查结果为正常的53例患者为对照组。检测并比较各组血清SFRP5、FGF21、IGF-I、血脂水平,分析血清SFRP5、FGF21、IGF-I与血脂和Gensini积分的相关性。结果:不同类型、不同冠脉病变程度CHD患者的血清SFRP5、FGF21、IGF-I、HDL-C水平均低于对照组,血清TC、TG、LDL-C水平均高于对照组,差异有统计学意义(P<0.05);血清SFRP5、FGF21、IGF-I水平的差异比较中,UA组低于SAP组,AMI组又低于UA组,中度病变组低于轻度病变组,重度病变组又低于中度病变组,差异均有统计学意义(P<0.05);血清TC、LDL-C水平的差异比较中,UA组高于SAP组,AMI组又高于UA组,中度病变组高于轻度病变组,重度病变组又高于中度病变组,差异均有统计学意义(P<0.05);而SAP组、UA组、AMI组之间两两比较以及轻度病变组、中度病变组、重度病变组之间两两比较的血清TG、HDL-C水平差异无统计学意义(P>0.05)。Pearson相关性分析结果显示:血清SFRP5、FGF21、IGF-I水平与TC、LDL-C、Gensini积分呈负相关(P<0.05)。结论:CHD患者血清SFRP5、FGF21、IGF-I水平均降低,且与血脂水平增高以及CHD病变程度加重均有关。     

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。     

乳酸菌在农业和食品加工中的应用研究进展

乳酸菌是发酵糖类物质的主要终产物为乳酸的细菌总称。常见的乳酸菌包括乳杆菌属（Lactobacillus）、片球菌属（Pediococcus）、明串珠菌属（Leuconostoc）、乳球菌属（Lactococcus）、链球菌属（Streptococcus）和双歧杆菌属（Bifdobacterium）等少数属的种类。许多乳酸菌属于人和动物胃肠道、泌尿生殖道、母乳、口腔等的正常菌群,能产生多种生物活性物质,具有调节肠道菌群平衡、增强机体免疫力、促进机体生长等益生功能,因而乳酸菌具有重要的应用价值。综述了乳酸菌在畜禽养殖饲料添加剂、青贮饲料发酵、水产养殖及植物病害防治等领域的应用研究进展,尤其在“饲料禁抗、养殖减抗、产品无抗”的养殖背景下,乳酸菌制剂是替代抗生素的最佳选择。总结了乳酸菌在奶制品、肉制品加工以及植物基饮料、低糖食品和饮料发酵等方面的开发潜力,展望了乳酸菌研究与应用的发展趋势。