Fluorescent vital staining of plant sexual cell nuclei with DNA—specific fluorochromes and its application in gametoplast fusion

DNA－binding fluorochromes are often used for vital staining of plant cell nuclei.However,it is not always sure whether the cells after staining still remain in living state.We chose several criteria to estimate the validity of real vital staining for sexual cell nuclei.These were:the cytoplasmic streaming in pollen tubes whose nuclei were stined,the simultaneous visualization of fluorochromatic reaction and nucleus staining in isolated generative cells,and the capability of isolated.prestained generative or sperm cells to fuse with other protoplasts.The results confirmed that 4,6-diamidino-2-phenylindole(DAPI),Hoechst 33258 and mithramycin could be used as real vital stains,though their efficiency varied from case to case;among them DAPI showed best effect.The fluo rescent vital staining technique offered a useful means foridentification and selection of heterokaryons in gametoplast manipulation studies.     

基于基质辅助激光解吸/电离飞行时间质谱的猪呼吸道病毒多目标鉴定方法的建立和应用北大核心

【目的】建立能高效同步鉴定猪伪狂犬病毒(porcine pseudorabies virus,PRV)、猪圆环病毒2型(porcine circovirus 2,PCV-2)和3型(porcine circovirus 3,PCV-3)、非洲猪瘟病毒(African swine fever virus,ASFV)以及猪博卡病毒1型(porcine bocavirus group 1,PBoV-G1)、2型(porcine bocavirus group 2,PBoV-G2)和3型(porcine bocavirus group 3,PBoV-G3)等呼吸道病毒的核酸基质辅助激光解吸/电离飞行时间质谱(matrix-assisted laser desorption/ionization time-of-flight mass spectrometry,MALDI-TOF MS)高通量多目标检测技术。【方法】根据7种病原体基因的保守序列,分别设计不同病原的引物及对应的单碱基延伸探针,通过引物浓度和反应条件优化,方法特异性、敏感性和稳定性分析,以及临床样本和猪源产制品的检测验证,建立常见猪呼吸道DNA病毒的MALDI-TOF MS多目标检测体系。【结果】质谱分析显示,多目标检测体系的7种靶标产物峰只在特定病毒阳性样品检测时产生,与其他病原体检测无交叉反应,表明该方法对7种靶标病毒检测特异性良好。重复性试验结果分析显示,体系中每种病毒在高、中、低浓度时批内阳性符合率均≥98.0%,批间均≥98.3%,表明该方法具有较高的稳定性。体系中7种病原体每种病毒最低检测限在8.65–26.27拷贝/μL之间,与荧光PCR(real-time fluorescence quantitative PCR,RT-qPCR)检测方法相当。采用MALDI-TOF MS多重检测方法对100份组织、饲料和猪肉样品进行检测应用,检出2种及以上混合感染样品39份,其中5份样本同步检出5种病原体阳性;对8份ASFV-p72假病毒人工污染样品进行验证,均可检出ASFV阳性。将以上样本检测应用结果与荧光PCR方法进行比对验证,2种方法对于不同病原体检测结果的符合率高达94.4%–100%。【结论】本研究建立的基于MALDI-TOF MS的猪呼吸道常见DNA病毒多重检测方法为猪群相关疫病快速监测和鉴别诊断,以及便利化进出口动物检疫等提供了一种新的敏感、特异的高通量多目标检测技术。     

五个猕猴桃种的皮孔、气孔器和叶片下表皮微观特征

为了探讨不同种类猕猴桃皮孔、气孔器和叶片下表皮特征的差异及其分类学意义,该文利用光学显微镜观察五个猕猴桃种共计9份样品材料的一年生枝条韧皮部上皮孔的形态,结果发现供试猕猴桃皮孔呈长椭圆形或长梭形,不同种皮孔的长×宽、皮孔密度、皮孔面积和皮孔面积的百分比值存在差异但与种类划分无明显规律,皮孔的宽可明显区分所选4个中华猕猴...     

Platelet-activating factor (PAF) and its relation to prostaglandins, leukotrienes and other aspects of arachidonate metabolism

This article summarizes some of the previously reported findings regarding a lipid mediator known as platelet-activating factor (PAF), and briefly describes its effects on cells and tissues. The effects of PAF have also been considered in relation to certain products of arachidonate metabolism released in response to PAF.     

Epidemiology of bluetongue in Central America and the Caribbean: initial entomological findings

Abstract. Forty-four species of Culicoides (Diptera: Ceratopogonidae) were caught in insect light traps during the first 2 years of studies on the epidemiology of bluetongue virus in the Caribbean and Central America. Traps were operated near sentinel ruminants which were bled monthly for serologic evaluation and then virus isolation. More than 570,000 individuals were identified. Culicoides insignis Lutz accounted for 90% of the catch, C.filarifer Hoffman/C.ocumarensis Ortiz 5%, C.furens Poey 3% and C.pusillus Lutz 2%. Other species accounted for less than 1% of the total catch. Sentinel ruminants became seropositive when C.insignis populations were high at many study sites. At a few sites C.pusillus and C.filarifer I C.ocumarensis were predominant or were present in large numbers during seroconversions of sentinels. Virus isolations were obtained from sentinel ruminants during times when these same species were present in large populations.     

桂林喀斯特石山檵木群落不同恢复阶段种间联结研究

为揭示桂林喀斯特石山檵木群落自然恢复过程中不同阶段主要物种种间相互作用变化规律,该文采用空间代替时间的方法,通过多物种间的总体关联显著性检验、χ2统计量分析和Spearman秩相关检验对桂林喀斯特石山檵木群落不同恢复阶段主要物种进行种间联结分析.结果表明:(1)在灌木阶段,主要物种种间关系呈不显著负相关;在乔灌阶段,乔...     

Regulation of platelet-activating factor (PAF) activity in human diseases by phospholipase A2 inhibitors, PAF acetylhydrolases, PAF receptor antagonists and free radical scavengers.

The aim of this review is to present recent findings indicating the likely involvement of platelet-activating factor (PAF) in human diseases, and possible ways of alleviating its harmful effects. PAF is a potent proinflammatory mediator and promotes adhesive interactions between leukocytes and endothelial cells, leading to transendothelial migration of leukocytes, by a process of juxtacrine intercellular signalling. This process leads to activation of leukocytes and the release of reactive oxygen radicals, lipid mediators, cytokines and enzymes. These reaction products subsequently contribute to the pathological features of various inflammatory diseases. The reactive oxygen radicals cause low density lipoprotein (LDL) oxidation which mediates the development of atherosclerosis. Oxidized LDL may damage cellular and subcellular membranes, leading to tissue injury and cell death. Among the therapeutic approaches considered are agents that inhibit/degrade proinflammatory mediators and thereby have anti-inflammatory and/or anti-atherogenic potential. These include inhibitors of phospholipase A2 activity, PAF-acetylhydrolases, PAF antagonists and free radical scavengers/antioxidants, the latter protecting against oxidized LDL-induced cytotoxicity.     

广东省中山市2种红树林有害生物风险分析及防控策略

【目的】了解红树林有害生物风险及其防控,维护红树林健康生长,发挥红树林的生态功能。【方法】2018—2019年,连续2年对广东省中山市红树林有害生物种类进行系统调查监测,并对薇甘菊和星天牛2种有害生物在中山市的分布状况、定殖和扩散的可能性、潜在危害性、受害对象的重要性、防控难度等进行分析,结合红树林的生态效益,参照国际有害生物风险性分析方法对两者在中山市红树林的危害风险性进行综合分析评估。【结果】调查发现,中山市红树林主要有害生物有23种,其中薇甘菊、星天牛最为严重,评估风险性R值分别为1.63和1.61,属中度危险的林业有害生物。【结论】薇甘菊和星天牛目前仅在中山市红树林局部地区发生危害,但具有明显扩散蔓延趋势,应该建立以应急除治、生物防治、生态修复等多种技术相结合的生态控制技术体系。     

白额巨蟹蛛对红头丽蝇捕食行为的初步观察

本文首次报道了在实验条件(温度19～23 ℃、相对湿度80 %)下白额巨蟹蛛对红头丽蝇的捕食行为和捕食功能反应的初步观察结果,并用Holling-Ⅱ型功能反应模型进行拟合,白额巨蟹蛛捕食红头丽蝇的功能反应直线回归方程为:NA＝1.0031 N/(1 0.0626 N).本研究结果,可以为蜘蛛控制卫生害虫提供理论依据.