Propagation of Toxoplasma gondii in suspension cultures of HeLa cells.

A novel method of Toxoplasma gondii cultivation in suspension cultures has been introduced using silicone-coated glass vessels (working volume 100 ml). The cells were kept in suspension by a magnetic impeller at 75 rpm at a temperature of 37 degrees C. HeLa cells grown on MEM with calf serum were used as host substrate. The HeLa cells were infected with zoites of Toxoplasma gondii virulent P strain. After seven days the host cells were destroyed by the toxoplasmas and the number of zoites was up to 24 x 10(6)/ml.     

Prevalence of Toxoplasma gondii in small mammals from the Ardennes region, France

Serum samples from 218 small mammals trapped in forest and grassland in the Ardennes region (North-eastern France) were tested for antibodies to Toxoplasma gondii. Using the modified agglutination test, positive results were found in 4/92 Apodemus sp., 3/64 Clethrionomys glareolus, 0/26 Microtus agrestis, 0/4 Micromys minutus, 3/5 Sorex sp., 2/9 Arvicola terrestris, and 7/18 Talpa europaea. Toxoplasma gondii was not isolated from the heart of seropositive individuals after bioassay in mice. Seroprevalence was significantly higher in large fossorial mammals living in grassland than in small forest mammals, probably related to ecological factors.     

Serodiagnosis of Toxoplasma gondii in habitually aborting women and other adults from North Jordan

The prevalence of anti-Toxoplasma gondii antibodies in serum samples of 55 habitually aborting women, 46 women with normal pregnancies, 92 outpatient adults, and 150 University students from North Jordan was studied using the enzyme linked immunosorbent assay (ELISA). Sera from the habitually aborting group were also tested by the indirect immunofluorescent (IIF) test. No significant difference was found between the overall prevalence rates in University students, outpatient adults and women with normal pregnancies (25.3%, 22.8% and 26.1% respectively). The prevalence in habitually aborting women exceeded two times that in women with normal pregnancies or in outpatient females (58.2%, 26.1% and 25.0% respectively), and was approximately three times that in female University students (18.3%). The greatest difference in the prevalence rate between habitually aborting women and those with normal pregnancies or outpatient females was found in groups having the highest antibody level (greater than or equal to 100% of standard positive controls). A positive correlation between the results of the ELISA and those of the IIF test occurred at titres of greater than or equal to 1:40 of the latter test in habitually aborting women.     

Interaction between macrophages of various origin and Toxoplasma gondii under conditions in vitro.

The study of proliferation of a virulent strain of Toxoplasma in cultures of macrophages of various origin revealed a certain sequence in the development of the pathogen: penetration and phagocytosis of the parasite, the stage of disintegration of one part of population and active proliferation of the other, resulting in the destruction of host cells. It was found that the penetration and phacocytosis were more active if macrophages from resistant animals (rats) were used, in comparison with those isolated from susceptible animals (white mice, guinea pigs). The activity of proliferation of a virulent strain of Toxoplasma also differs with the host cells: the toxoplasma multiply more rapidly in macrophages from susceptible animals than in those from resistant animals. The following changes of macrophages due to proliferation of the parasite were observed: change of form of the cell accompanied with the loss of cytoplasmatic processes, vacuolation of the cytoplasm, displacement of the nucleus towards the periphery followed by its pycnosis and rupture of the cell.     

对比分析不同方法提取土壤中的二氯喹啉酸

本文采用4种常用方法分别对福建田土中添加的二氯喹啉酸进行了提取,并采用高效液相色谱法对其添加回收率进行了测定,对比分析表明,当二氯喹啉酸添加浓度为1.25μg/g时,方法二即氢氧化钠溶液提取、乙酸乙酯净化法回收率最高,约为70%,且杂质峰较小,基线平稳,峰形较对称;重复性高,两次生物学试验的平均回收率无显著差异,均略高于70%。方法一即乙腈磷酸水溶液提取、氯化钠净化法,回收率较高,但杂质峰较高,基线不平稳。方法三即硼砂甲醇溶液提取、二氯甲烷净化法,虽然杂质峰小、基线平稳、峰形较好、但回收率低,约为50%。方法四即甲醇磷酸水溶液直接提取法,因提取液难以在旋转蒸发仪中浓缩,因此未继续检测。综合结果表明,方法二最适用于福建省水稻田二氯喹啉酸的提取。     

面积高程积分值计算方法的比较

面积高程积分值(Hypsometric index)能够对流域地貌发育阶段进行定量的描述,在地貌学中得到了广泛的应用.关于该值的计算方法较多,然而,在实际应用中,哪种方法才能带来更便捷准确的结果,尚缺乏探讨.文中基于Arcgis9.3及SRTM-DEM数据,以白龙江流域32个子流域为例,分别利用积分曲线法、体积比例法及起伏比法求取了各子流域的HI值.结果表明:三种方法计算的HI值几乎一致,但起伏比法是计算HI值最高效简捷的方法;积分曲线法及体积比例法在流域数目较少时可以使用,但流域数目较多时不推荐使用.该结果可为利用HI值进行地貌研究提供借鉴.     

板栗疫病菌脱毒方法的比较研究

 病毒与宿主相互作用中,存在宿主主动或被动摆脱病毒的机制。本研究用光照诱导-单孢分离、原生质体再生和菌丝尖端分离3种方法对携带低毒病毒的板栗疫病菌(Cryphonectria parasitica)的EP721、EP713和Euro7三个菌株的脱毒效率进行了比较。结果表明:经光照诱导-单孢分离后所有菌株均可获得脱毒菌株,而原生质体再生对EP721的脱毒效率最高,是继光照诱导-单孢分离脱毒法之后另一种新的有效的脱毒方法,特别适用于不产孢的真菌脱毒。     

小麦光腥黑粉菌冬孢子总DNA提取方法比较

以小麦光腥黑粉菌冬孢子为试验材料,比较分析了改良CTAB法、氯化苄法、SDS法对小麦光腥黑粉菌冬孢子总DNA提取的效果。结果表明,SDS法无论在DNA纯度(R=A260 nm/A280 nm)和产量上均优于氯化苄法和CTAB法。利用SDS法能获得186 ng/mg的DNA产率,而氯化苄法和CTAB法只能分别获得145 ng/mg和112 ng/mg。采用SDS法提取的DNA纯度较高,-RSDS=1.485,氯化苄法(BC)和CTAB法所得DNA纯度无明显差异,分别为-RCTAB=1.254和-RBC=1.264。     

Transfer of delayed hypersensitivity through repeatedly sensitized peritoneal exudate cells during experimental ancylostomiasis in mice

Current investigations using sensitized peritoneal exudate cells from mice infected repeatedly with Ancylostoma caninum larvae supply the evidence that these cells have the capability to transfer passive immunity to isogeneic recipients in contrast to normal cells from uninfected donors. High doses of sensitization to donors and a lapse of time between the expansion and proliferation of cells in the recipients provide a rather strong immunological readiness to expel/destroy the worm burden. The larvae bore through the gut reaching the peritoneal cavity but cannot enter the liver and/or lungs; they are thus misled (in the absence of normal guiding influences) to muscles where they undergo allergic death.     

Comparison of the effectiveness of five extraction methods for Clavibacter michiganensis subsp. sepedonicus and Ralstonia solanacearum from potato tubers

In the EU Control Directives, the recommended extraction procedure for testing potatoes for Clavibacter michiganensis subsp. sepedonicus and Ralstonia solanacearum comprises incubation followed by differential centrifugation. This method can be qualified as complex because of the number of different steps required. This study evaluates five different extraction methods for each bacterium from both a technical point of view and for the quality of the results. Results showed that in the case of C. m. sepedonicus the clarification step should be avoided. The incubation/shaking method with three subsamples gives at least as satisfactory results as the official EU procedure. It also has other advantages, facilitating immunofluorescence readings due to the reduced quantity of plant debris, and improving the speed and the reliability of the analysis.     

三种PCR方法检测柑橘黄龙病菌的效果比较

为了比较常规PCR、巢式PCR和实时荧光定量PCR方法在大田检测中对柑橘黄龙病(Huanglongbing, HLB)的检测效果, 首先比较了3种检测方法对柑橘黄龙病菌检测的灵敏度, 结果发现：3种检测方法的灵敏度依次为常规PCR<巢式PCR<实时荧光定量PCR。运用3种检测方法对广东5个柑橘品种上的189个黄龙病疑似病样进行检测, 结果发现：黄龙病检出率依次为常规PCR<巢式PCR<实时荧光定量PCR。研究表明：常规PCR适合以较低成本大规模检测黄龙病; 实时荧光定量PCR具有最大的检测灵敏度; 巢式PCR检测技术同时具有前两者的一些优点, 但操作较复杂, 适合技术熟练的研究者使用。     

Comparison of solvents and methods of extracting methylbenzimidazol-2-yicarbamate (MBC) from tobacco

The bioautographic method of Homans and Fuchs for detecting MBC on thin layer plates, was tested quantitatively. The sum of the vertical and horizontal diameters of the zones of inhibition of Penicillium expansum, and the square root of the mass of an equal area of paper, were directly proportional to the logarithm of the concentration of MBC. Methanol and ethanol extracted significantly more MBC from tobacco tissue than acetone and chloroform. Soxhlet extraction was more effective than cold (22 °C) treatment, but the latter, in which 100 mg aliquots of dried tissue were used, was the least variable, very much quicker and could be used to detect the fungicide in small amounts of individual plant tissues.     

Allelopathic activity of leaching from dry leaves and exudate from roots of ground cover plants assayed on agar

The effects of leaches from dry leaves of 71 ground cover plant species on lettuce were tested at the first screening. The inhibitory effects on radicle and hypocotyl elongations of lettuce varied with the different species of cover plants that were used. Eight species of Oxalis showed strong inhibitions (4–27% of untreated control on radicle elongation). Inhibitory activities of seven species of cover plants on three weed species, live amaranth ( Amaranthus lividus ), southern crabgrass ( Digitaria ciliaris ) and common lambsquarters ( Chenopodium album ), were tested at the second screening. Moss pink ( Phlox subulata ), trefoil ( Oxalis brasiliensis ), red spiderlily ( Lycoris radiata ), creeping thyme ( Thymus serpyllum ), European pennyroyal ( Mentha pulegium ), roman chamomile ( Chamaemelum nobile ) and star-of-Bethlehem ( Ornithogalum umbellatum ) were selected as donor plants because of their high inhibitory effects on lettuce growth and their usefulness as ornamental ground cover plants. Effects of leaches from dry leaves and exudates from the roots of these species were assayed on agar. Radicle elongations of all tested weed species were inhibited by leaches from trefoil and red spiderlily (8–31% and 14–24% of untreated control, respectively) and exudates from moss pink, trefoil and creeping thyme (11–43%, 31–74% and 22–67% of untreated control, respectively).     

几种方法在粮食总产量预测中的对比

根据吉林省1978~2007年的农业数据,选定了14个影响农业生产的因素作为研究对象,分别采用了主成分分析法、BP神经网络法、灰色预测法和逐步回归分析法4种分析预测方法,通过SPSS和Matlab工具将原始数据进行处理,得到4种不同的预测模型,进而基于这4种模型对吉林省的粮食产量进行预测,并将各种预测产量和实际产量进行拟合分析。研究结果表明,拟合性最好的是BP神经网络法,其拟合确定性系数为0.899;其次是主成分分析法(拟合确定性系数为0.834)和逐步回归法(拟合确定性系数为0.787);拟合效果最差的是灰色预测法(确定性系数为0.744)。粮食总产量估算精度最高的是BP神经网络法,达到93.67%;其次是主成分分析法,为90.45%。     

A light microscopic study of the course of cellular division of Giardia intestinalis trophozoites grown in vitro.

The cellular division of trophozoites of Giardia intestinalis group was followed microscopically in stained preparations from axenic cultures. Eleven successive stages were described, documented by photomicrographs and their survival times calculated.     

辣椒轻斑驳病毒检测方法的比较

为寻求一种灵敏、经济、快捷检测辣椒轻斑驳病毒(Pepper mild mottle Tobamovirus,PMMoV)的检测方法,以辣椒轻斑驳病毒侵染的甜椒叶片为材料,采用DIG标记的核酸斑点杂交、RT-PCR和DAS-ELISA 3种方法检测不同系列稀释倍数的辣椒叶片总RNA和叶片提取液,测试3种方法的稀释限点.结果表明,RT-PCR灵敏度最高,地高辛斑点杂交灵敏度次之,DAS-ELISA灵敏度最低.在3种方法中地高辛斑点杂交方法与其他两种方法相比灵敏度较高,不需要任何特定仪器,而且适合大量样品的检测,所以此方法有很好的应用前景.     

玉米茎腐病病原菌检测方法研究

为提高玉米茎腐病病原菌检测结果的准确性和可信度,以组织分离法做对比,采用分子检测法,对采自田间的189个玉米茎腐病病株进行真菌种类的鉴定和数量的统计。结果表明,分子检测法对腐霉Pythiumspp.的检出频率为29.24%,对镰孢菌Fusariumspp.的检出频率为73.68%,组织分离法对腐霉的检出频率仅为0.58%,对镰孢菌的检出频率为60.82%,两方法的符合率最高仅为35.92%,最低为0。因此,采用组织分离和分子检测相结合的方法可提高玉米茎腐病病原菌鉴定结果的准确性。     

三种不确定性水质综合评价方法比较研究

将BP与SOM人工神经网络模型与模糊综合评价法进行实例比较研究,以探讨这三种不确定性水质综合评价方法的科学合理性及其适用范围.主要结论为:1)BP与SOM网络模型通过对样本的学习来获得水质指标与水质类别之间的映射关系,评价结果更客观.2)模糊综合评价法通过构建隶属函数对水质进行分类,评价结果偏重,易引起过保护.3)当水...