红肉脐橙果肉中主要色素的定性及色素含量的变化

 运用薄层层析法及二极管阵列检测器与高效液相色谱联用的方法, 确定红肉脐橙果肉中含有番茄红素和β- 胡萝卜素两种主要色素, 它们在液相色谱图中占总峰面积(计溶剂峰) 的73. 57 %～77. 78 % , 番茄红素占55. 36 %～58. 49 % , β- 胡萝卜素占18. 21 %～19. 93 %。利用反相高效液相色谱仪以及番茄红素和β- 胡萝卜素标样制作标准曲线, 测定果实发育及室温贮存过程中色素的变化动态, 结果表明, 该脐橙果肉中的番茄红素在成熟期含量最高, 达109. 67μg·g^-1DM, β- 胡萝卜素此时也达到最高值(15. 52μg·g^-1DM) ; 番茄红素的含量在采收后基本呈下降趋势(但采后30 d 有显著升高) , 说明果肉中存在类胡萝卜素采后合成的现象; 贮存4 个月后, 番茄红素含量急剧降低至最高时的1/ 10。     

窥探我国果农的合作之路

改革开放以来,我国果业迅猛发展,但产销体制很不完善,产品本身不等于商品,更不等于有了稳定畅销的渠道和市场份额。分散的个体果农户面对竞争的市场,犹如汪洋大海中的叶叶扁舟,显得无能为力。果农协会组织和引领分散果农走向市场,作为利益共享、风险共担的非盈利组织形式,在国外已经是成功的经验和模式,应成为我们之鉴。为振兴我国果业,合作化是我国个体果农的必由之路。果农协会应当实行完全民主化运作,避免“权力”的介入而使之变为“半官方化”、“机关化”和“官僚化”。政府应在制订政策条例、协助开拓市场、科技服务等方面发挥其作用。果农的教育和科技水平亟待提高,民主意识亟待培养和增强。政府在这些方面大有可为。     

红肉脐橙(Citrus sinensis L.)果肉中特征色素提取方法探索

红肉脐橙是目前为止惟一果肉呈粉红色或红色的脐橙,其呈色色素尚未见报道。为深入研究其果肉中特征色素的构成及在果实生长发育和贮存过程中色素含量的变化,本研究在对该色素初步定性的基础上对提取方法进行了探索。在分析红肉脐橙果肉中色素萃取液的紫外可见吸收光谱时发现,该色素有类胡萝卜素的特征吸收峰,将萃取液进行薄层层析则进一步证实其内含有番茄红素。在色素提取的前处理方式上,本研究认为冷冻干燥样品的浸提效果较真空干燥的样品稳定(变异系数小),且浸提率相差无几,所以选择冷冻干燥作为合适的样品前处理方式。色素浸提条件的正交实验结果表明,最佳浸提条件为50℃、1.5h内浸提4次,浸提的料液比为1:60。此外,浸提温度、浸提时间、浸提料液比和浸提次数对浸提率都有显著影响,影响最大的因素是浸提温度,最佳温度为50℃,随温度降低浸提率显著降低。其次是侵提时间的长短,最佳浸提时间为1.5h,延长或缩短0.5h都会使浸提率下降。浸提次数对浸提率的影响是最小的。     

Seasonal distribution of phytoplasmas in Australian grapevines

The distribution and persistence of phytoplasmas were determined in Australian grapevines. Phytoplasmas could be detected using the polymerase chain reaction (PCR) from shoots, cordons, trunks and roots throughout the year, and phytoplasmas appear to persistently infect Australian grapevines from year to year. Phytoplasmas were not always detected in samples from the same sampling area from one sampling period to the next. Phytoplasma detection by PCR was improved by sampling from shoots, cordons and trunks, especially during October (early spring). The diseases expressed by the 20 grapevines used in the distribution and persistence studies were monitored. Australian grapevine yellows disease (AGY) was expressed by 17/20 grapevines at some time during the study, whilst only 4/20 and 15/20 grapevines expressed restricted growth disease (RG) and late season leaf curl disease (LSLC), respectively. All grapevines with RG and LSLC also had AGY. The three diseases were persistently expressed in some grapevines and remission of disease was observed in others. The results of PCR detection in the same grapevines indicated that phytoplasmas were more frequently detected in AGY-affected grapevines that also expressed RG and LSLC compared with grapevines expressing AGY alone. Phytoplasmas were detected in symptomless plant material but less frequently compared with AGY-affected material.     

Rapid detection of Phytophthora cinnamomi using PCR with primers derived from the Lpv putative storage protein genes

Phytophthora cinnamomi is an ecologically and economically important pathogen. In this study, PCR assays were developed with primer pair LPV2 or LPV3 for rapid detection and identification of this organism. Both primer pairs were selected from putative storage protein genes. The specificity of these primer pairs was evaluated against 49 isolates of P. cinnamomi , 102 isolates from 30 other Phytophthora spp., 17 isolates from nine Pythium spp. and 43 isolates of other water moulds, bacteria and true fungi. PCR with both primer pairs amplified the DNA from all isolates of P. cinnamomi regardless of origin. The LPV3 primers showed adequate specificity among all other species tested. The LPV2 primers cross-reacted with some species of Pythium and true fungi, but not with any other Phytophthora species. PCR with the LPV3 primers detected the pathogen at levels of a single chlamydospore or 10 zoospores in repeated tests. The PCR assay was at least 10 times more sensitive than the plating method for detection of the pathogen from artificially infested soilless medium, and, to a lesser extent, from naturally infected plants. PCR with LPV3 primers can be a useful tool for detecting P. cinnamomi from soilless media and plant tissues at ornamental nurseries, whereas the LPV2 primers can be an effective alternative for identification of this species from pure culture. Applications of these assays for detection of P. cinnamomi in other environments were also discussed.     

免疫亲合色谱及在农药残留分析中的应用

免疫亲合色谱可用于复杂样本中微量目标分析物的选择性分离富集。综述了免疫亲合色谱的基本原理、方法的建立过程(包括抗体的制备、固相基质的筛选、抗体与基质的偶联、免疫亲合色谱条件的优化)、免疫亲合色谱在农药残留分析中的应用现状及发展趋势。     

小麦苗枯病菌的ITS分析及PCR检测

 小麦苗枯病菌(Clavibacter fangii,Cf)是引起小麦细菌性苗枯病的病原,本研究用16S~23S rDNA间的内源转录间隔区(internally transcribed spacer,ITS)序列通用引物L1(5'-AGTCGTAACAAGGTAGCCGT-3')和L2(5'-GTGCCAAGGCATCCACC-3')扩增Cf和其它相关细菌的基因组DNA;并对其PCR产物进行回收、克隆和测序,将所获序列和其它已报道的细菌ITS序列进行多重比较后设计出Cf的特异性引物I1(5'-TGCCAAGTCACACTGAGACGA-3')和I2(5'-CAATGATCTACCACCCTCCGA-3')。此引物可以从Cf中扩增出351bp的特异性片段,而其余参试的21个细菌PCR反应结果均为阴性。该方法可以应用于小麦苗枯病菌的快速、可靠检测。此外,本研究对多种植物病原棒形杆菌的ITS序列进行比较研究,发现其具有一定的分类意义。     

利用RT-PCR检测库尔勒香梨苹果茎痘病毒的研究

 以库尔勒香梨新鲜、冷藏、冷冻叶片和皮层为材料,对提取双链RNA (dsRNA)的2种方法和提取总RNA的3种方法进行了分析比较,并对总RNA的提取方法进行了改进,获得了纯度较高、完整性较好的dsRNA和总RNA,在此基础上进行了反转录(RT)和PCR扩增。在国内首次完成了对苹果茎痘病毒(ASPV)的RT-PCR检测,建立了ASPV有效RT-PCR反应体系。用此体系扩增到ASPV一个长约316 bp的片段。实验表明以dsRNA和总RNA为模板均能成功进行RT-PCR检测,且dsRNA优于总RNA。     

不同引物对植原体的检测灵敏度比较研究

用常规PCR和巢式PCR对目前常用的各种植原体引物(fPl/rP7、fU5/rP7、fU5／rU3、fAY/rEY和fFD9/rFD9)的检测灵敏度进行了比较研究。研究发现，它们的检测灵敏度并不相同。最灵敏的引物(fAY/rEY)要比最不灵敏的引物(fFD9/rFD9)的灵敏度至少高出数千倍。因此，按照不同的检测目的选择所用的检测引物是明智的，特别是当待测样品中的植原体浓度极低时，比如葡萄组织样品中植原体的检测。据此提出了用于不同检测目的时的最佳引物。     

有效碳数法研究及其在农药气相色谱分析中的应用

有机化合物结构与其所含有的有效碳数有一定的关系，本文给出了２０类结构化合物及其所含有有效碳数的关系，并对理论计算值和实测值进行了比较，结果十分接近，利用有效碳数法可以设计农药分析实验方案和无标样的情况下测定农药杂质含量。