短波紫外线照射对‘金都’火龙果采后保鲜的影响

以‘金都’火龙果(Hylocereus polyrhizus ‘Jindu’)果实为试材,采用波长254 nm紫外杀菌灯为辐射源,给予不同剂量短波紫外线(Ultraviolet-C,UV-C)照射处理,探讨低剂量UV-C对火龙果采后保鲜的影响及作用机理。结果表明,不同剂量UV-C照射处理能有效抑制‘金都’火龙果果实腐烂和电导率上升,降低果实TSS含量,其中1.0 kJ·m–2紫外线辐照效果最好。1.0 kJ·m–2 UV-C处理能极显著提高贮藏期火龙果的SOD和CAT活性,显著提高贮藏早中期的几丁质酶活性和PPO活性,β-1,3葡聚糖酶活性在贮藏后期也显著高于对照,但降低了火龙果贮藏中期(第6天)的POD活性。此外,1.0 kJ·m–2 UV-C处理显著提高火龙果贮藏期H2O2含量(除第6天外),对果实的失水率无影响。采后火龙果应用适当剂量UV-C照射可提高抗病性,延长贮藏保鲜期。     

遮荫对彩叶植物矾根夏季适应性表型的影响

以彩叶植物矾根(Heuchera micrantha)‘蜜桃’(‘Georgia Peach’)、‘小珍珠’(‘Petite pearl fairy’)、‘花毯’ (‘Tapestry’)为材料,研究不同遮荫处理对矾根观赏特征、高温半致死温度以及成活率的影响。结果表明,在遮荫条件下,三个矾根品种株高增加、叶面积变大、花序变长、开花推迟,‘蜜桃’和‘小珍珠’花期延长,‘花毯’花期缩短。遮荫引起‘蜜桃’和‘小珍珠’叶绿素含量、类胡萝卜素含量显著上升,花色素苷含量明显下降,叶色由红、紫色向灰绿色转变,叶片彩化度下降;‘花毯’的叶绿素、类胡萝卜素和花青素含量均随遮荫度增加显著上升,其叶色由浅绿转为深绿,叶脉紫红色加重,彩化度提高,观赏性增强。随着遮荫度提高,三个矾根品种的高温半致死温度明显升高,成活率显著上升。相关性分析表明,三个矾根品种的成活率与最高气温、最大光强、气温、光强分别存在极显著负相关关系,与相对湿度以及该品种的高温半致死温度分别存在极显著正相关关系。多元逐步回归分析表明,高光强是引起‘蜜桃’成活率下降的关键因素,‘小珍珠’的成活率主要取决于高温半致死温度,‘花毯’的成活率主要受极端高温的影响。     

隐匿性胫骨平台骨折MRI、CT检查的影像学表现及其诊断价值对比的回顾性研究

目的:研究对比隐匿性胫骨平台骨折(TPOF)磁共振成像(MRI)、电子计算机断层扫描(CT)检查的影像学表现及其诊断价值。方法:回顾性分析我院自2016年1月至2019年12月拟诊断为TPOF且X线检查表现为阴性的89例患者的临床资料,分别对所有受试者进行MRI、CT检查,且以手术检查为金标准,比较上述两种影像学检查手段诊断TPOF的效能。此外,比较MRI、CT检查诊断TPOF的表观扩散系数以及节段各向异性值以及对TPOF类型的检出率。结果:MRI检查诊断TPOF的灵敏度、特异度及准确度分别为98.61%、94.12%、97.75%,均高于CT检查的79.17%、64.71%、76.40%(均P<0.05)。MRI检查诊断TPOF的表观扩散系数高于CT检查,而节段各向异性值低于CT检查(均P<0.05)。MRI检查对骨皮质骨折的检出率低于CT检查,而对骨小梁骨折的检出率高于CT检查(均P<0.05)。结论:MRI检查诊断TPOF的价值高于CT检查,且在骨小梁骨折的检出率方面优于CT检查,但CT检查应用于骨皮质骨折的诊断价值更高。临床工作中可能通过联合MRI以及CT检查,继而达到提高TPOF检出率的目的。     

小麦抗赤霉病外源种质的创制和育种利用

小麦赤霉病是危害小麦安全生产的重要病害之一,种植抗病品种是防治赤霉病最经济有效的手段。目前在生产上应用的抗源很少,越来越多的研究者将目光转移到小麦的近缘属种,寻找新的抗源以及寻求新的育种突破。携带抗性基因的外源染色体可以通过染色体工程手段以附加系、代换系和易位系等形式导入小麦。综述了将大赖草等多个小麦近缘种的抗赤霉病基因导入普通小麦、创制抗病外源种质和育种利用的最新研究进展,以期为小麦抗赤霉病育种提供参考信息。     

三疣梭子蟹软壳硬化阶段肝胰腺的营养成分及脂肪酸组成分析

采用常规营养物质测定方法和气质联用(GC-MS)技术,研究了三疣梭子蟹软壳硬化阶段肝胰腺的基本营养成分和脂肪酸组成。结果发现在其软壳硬化的过程中肝胰腺指数、粗脂肪和灰分含量逐渐降低,而粗蛋白含量趋势相反;表明脂类是主要的能源物质。共检测出42种脂肪酸,其中C16:0(棕榈酸)、C18:1(n-9)(油酸)和C22:6(n-3)(DHA)是主要脂肪酸;蜕壳后0～6 h,单不饱和脂肪酸(MUFA)在肝胰腺中的含量显著降低(P<0.05),而饱和脂肪酸(SFA)和多不饱和脂肪酸(PUFA)的含量则均有不同程度的上升;6～48 h,MUFA在肝胰腺中的含量逐渐上升,PUFA的含量则与其相反;SFA在6～24 h时降低,随后升高;∑EPA+DHA在肝胰腺中的含量与∑PUFA的含量变化趋势一致。     

Rational design of microRNA–siRNA chimeras for multifunctional target suppression

MicroRNAs (miRNAs) are involved in a variety of human diseases by simultaneously suppressing many gene targets. Thus, the therapeutic value of miRNAs has been intensely studied. However, there are potential limitations with miRNA-based therapeutics such as a relatively moderate impact on gene target regulation and cellular phenotypic control. To address these issues, we proposed to design new chimeric small RNAs (aiRNAs) by incorporating sequences from both miRNAs and siRNAs. These aiRNAs not only inherited functions from natural miRNAs, but also gained new functions of gene knockdown in an siRNA-like fashion. The improved efficacy of multifunctional aiRNAs was demonstrated in our study by design and testing of an aiRNA that inherited the functions of both miR-200a and an AKT1-targeting siRNA for simultaneous suppression of cancer cell motility and proliferation. The general principles of aiRNA design were further validated by engineering new aiRNAs mimicking another miRNA, miR-9. By regulating multiple cellular functions, aiRNAs could be used as an improved tool over miRNAs to target disease-related genes, thus alleviating our dependency on a limited number of miRNAs for the development of RNAi-based therapeutics.     

Rapid Diversification of FoxP2 in Teleosts through Gene Duplication in the Teleost-Specific Whole Genome Duplication Event

As one of the most conserved genes in vertebrates, FoxP2 is widely involved in a number of important physiological and developmental processes. We systematically studied the evolutionary history and functional adaptations of FoxP2 in teleosts. The duplicated FoxP2 genes (FoxP2a and FoxP2b), which were identified in teleosts using synteny and paralogon analysis on genome databases of eight organisms, were probably generated in the teleost-specific whole genome duplication event. A credible classification with FoxP2, FoxP2a and FoxP2b in phylogenetic reconstructions confirmed the teleost-specific FoxP2 duplication. The unavailability of FoxP2b in Danio rerio suggests that the gene was deleted through nonfunctionalization of the redundant copy after the Otocephala-Euteleostei split. Heterogeneity in evolutionary rates among clusters consisting of FoxP2 in Sarcopterygii (Cluster 1), FoxP2a in Teleostei (Cluster 2) and FoxP2b in Teleostei (Cluster 3), particularly between Clusters 2 and 3, reveals asymmetric functional divergence after the gene duplication. Hierarchical cluster analyses of hydrophobicity profiles demonstrated significant structural divergence among the three clusters with verification of subsequent stepwise discriminant analysis, in which FoxP2 of Leucoraja erinacea and Lepisosteus oculatus were classified into Cluster 1, whereas FoxP2b of Salmo salar was grouped into Cluster 2 rather than Cluster 3. The simulated thermodynamic stability variations of the forkhead box domain (monomer and homodimer) showed remarkable divergence in FoxP2, FoxP2a and FoxP2b clusters. Relaxed purifying selection and positive Darwinian selection probably were complementary driving forces for the accelerated evolution of FoxP2 in ray-finned fishes, especially for the adaptive evolution of FoxP2a and FoxP2b in teleosts subsequent to the teleost-specific gene duplication.     

锌指核酸酶技术在植物基因工程中的应用

锌指核酸酶(zinc finger nucleases,ZFNs)由3到4个锌指结构(zinc fingers,ZFs)和FokⅠ核酸内切酶的剪切结构域组成。锌指核酸酶(ZFNs)通过锌指结构(ZFs)与特异核酸位点结合,再利用FokⅠ的酶切作用切割DNA,引起特异位点DNA双链断裂(double strand break,DSB)。DNA双链断裂可以通过非同源末端连接(non-homologous end joining,NHEJ) 或同源重组(homologous recombination,HR)来修复。在修复过程中实现对基因组DNA的靶向修饰。介绍了锌指核酸酶结构、人工构建途径,作用机理和试验步骤,重点综述了锌指核酸酶技术在植物基因工程的应用。     

肾移植术后HCMV感染与淋巴细胞亚群及肾功能的相关性

目的：肾移植患者由于术前透析及术后服用免疫抑制剂,显著增加了人巨细胞病毒（Humancytomegalovirus,HCMV）原发感染和潜伏感染被激活的机会。观察HCMV感染情况与血T淋巴细胞亚群及肾功能的变化,以探讨其相关性及临床意义。方法：跟踪收集40例肾移植患者术前、术后血标本,应用RT-PCR技术检测HCMV,流式细胞术检测淋巴细胞亚群,结合肾功能判断是否发生急性排斥或移植肾功能恢复延迟。结果：肾移植术后HCMV感染率为52．5％,10例出现症状性感染（25％）,出现阳性时间35．7±15．3天。症状性感染组CD3-bCD4＋的水平和CD4＋／CD8＋的比值较无活动性感染组和正常对照组均降低,CD8＋水平较其他组升高,差异有显著性意义（P〈0．05）。无症状性活动感染者与无活动性感染者各指标比较差异无显著性。活动性感染组急性排斥或移植肾功能恢复延迟发生8例（38．1％）,无活动性感染组发生1例（5．2％）,差异具有统计学意义（x^2=6．15,P〈0．05）。结论：肾移植术后HCMV感染能显著引起T淋巴细胞亚群变化,尤其是CD4＋／CD8＋。并与急性排斥或移植肾功能恢复延迟密切相关联,在其发生发展中可能起着重要的作用。三者相互联系、相互作用、互为因果,对进一步机制的研究及临床诊断治疗、预后方面有一定意义。