Food-borne human pathogenic viruses and their molecular detection with special consideration of noroviruses and hepatitis A virus in mussels

Viruses are increasingly important as etiological agents of gastrointestinal infections. Because of improved diagnostic methods, in particular, because of molecular biological techniques, viruses can be detected much more frequently as pathogens of foodborne diseases. Apart from the hepatitis A virus (HAV) the Norovirus (NLV) is becoming more significant. On an international level methods are developed to detect the amount of viruses which minimise PCR inhibitors and which are applicable in routine diagnostic. There are numerous routines available in the field of virus diagnostic in shellfish and oysters which are, however, not yet standardised and applicable in the whole of Europe. This review highlights viral agents their characteristics as well as food contaminated with viruses. While most of the detection methods are cited from the literature, own preliminary results of virus detection in mussels are discussed in addition.     

Generation of reactive oxygen species by a novel anthraquinone derivative in the cyanobacterium Planktothrix perornata (Skuja)

A water-soluble anthraquinone derivative (2-[methylamino-N-(1′-methylethyl)]-9,10-anthraquinone monophosphate), previously found to be selectively toxic towards Planktothrix perornata at submicromolar concentrations, was studied to determine its toxic mode of action towards this cyanobacterium. Chlorophyll fluorescence was monitored as an indicator of photosynthetic efficiency, and measurement of reactive oxygen species (ROS) was performed using the ROS-sensitive probe 2′,7′-dichlorodihydrofluorescein diacetate. The effects of the herbicide paraquat (a ROS generator) as well as ascorbate and α-tocopherol (ROS scavengers) on ROS formation by P. perornata were studied. Also, the effects of different concentrations of ascorbate, α-tocopherol, and the herbicide diuron on reducing the toxicity of the water-soluble anthraquinone derivative towards P. perornata were determined. Our results indicate that the water-soluble anthraquinone derivative does not inhibit photosynthetic electron transport directly, but does generate ROS at levels that may cause toxicity towards P. perornata.     

洋葱染色体核型的FISH分析

 挑选洋葱(Allium cepa L．) (2n=2x=16，CC)有丝分裂中期细胞，以洋葱卫星DNA序列(AC—SAT-DNA)为探针，DIG-1 1-dUTP为标记物，用荧光原位杂交(FISH)方法观察其在染色体上的定位，并进行洋葱的核型分析。6号染色体为近端部着丝点染色体，在其长臂末端有一个卫星DNA序列的主要位点。其余每条染色体在其长、短臂的末端都各具有一个主要位点。差异表现在各染色体上卫星DNA序列的次要位点分布不同。根据洋葱8对染色体各自具有的独特的卫星DNA分布位点，可将洋葱8对染色体全部分开。以此为基础，构建了洋葱卫星DNA在染色体上分布的模式图。     

Longterm effects of soil compaction and tillage on Collembola and straw decomposition in arable soil

Soil core samples were taken from May 1996 to October 1996 at four week intervals to assess the longterm effects of compaction due to soil tillage on Collembola in arable land. Two different tillage systems were studied: conservation tillage (CS) with rotary harrowing to 120 mm depth and conventional tillage (CT) with a mould board plough to 300 mm depth. Soil compaction was achieved by wheeling with graded loads: 0t, 2 × 2.5t and 6 × 5.0t (wheeling frequency × wheel load) in early spring 1995. Litter decomposition rate was investigated by the minicontainer-method, using two different mesh-sizes: 20 μm (excluding mesofauna) and 500 μ (including mesofauna). The substrate used was winter wheat straw, corresponding to the crop cultivated on the field.We recorded 25 species of Collembola. The abundance of Collembola during the growing season was at a minimum in June in both tillage systems. Thereafter, numbers of individuals increased, probably due to better nutrition. Mesaphorura krausbaueri s.l. was eudominant in CS. In CT Folsomia fimetaria and M. krausbaueri s.l. reached high abundances at the end of August. Harvesting and tilling supported population growth in CS, while numbers in CT decreased. The collembolan species showed different preferences in regard to the tillage system and the grade of compaction. During the first 4 weeks of exposure the decomposition rate of straw was highest. The decomposition rate in the minicontainers with 20 μm mesh-size was higher due to better moisture conditions for the microorganisms. After harvest and tilling the decomposition rate increased, especially in the CS-plots, because of aeration and incorporation of residues. Population fluctuation in the minicontainers was caused by migration of Collembola in response to changing moisture conditions. The main species in the minicontainers were large and mobile. Compared to the surrounding soil, species diversity was reduced.     

嘎拉苹果高温处理与果实日灼的关系

 高温处理对诱导果实增强对日灼的抗性有一定的作用 ,可降低日灼率。苹果果实在 4 5℃下处理 2h ,在3d后将处理果和对照果同时暴露在阳光下 ,结果发现 :热处理能够在一定程度上增强果实对日灼的抗性。在 4 5℃下处理 2、4和 6h后立即取样或室温下放置 2 4h后取样 ,对热激蛋白的分析表明 ,大分子量热激蛋白量变化不大 ,而小分子量热激蛋白可能在诱导果实抗热性方面起重要作用。随着处理时间延长 ,在一定时间范围内 ,热激蛋白抗热性水平增加。经测定 ,树冠外围充分曝光果和树冠内膛遮荫果对比 ,二者热激蛋白含量有显著差异 ,这可能是遮荫果对日灼更为敏感的原因。     

Equatorial X-ray Emissions: Implications for Jupiter's High Exospheric Temperatures

Observations with the High Resolution Imager on the Rontgensatellit reveal x-ray emissions from Jupiter's equatorial latitudes. The observed emissions probably result from the precipitation of energetic (>300 kiloelectron volts per atomic mass unit) sulfur and oxygen ions out of Jupiter's inner radiation belt. Model calculations of the energy deposition by such heavy ion precipitation and of the resulting atmospheric heating rates indicate that this energy source can contribute to the high exospheric temperatures(>800 kelvin at 0.01 microbar) measured by the Galileo probe's Atmospheric Structure Instrument. Low-latitude energetic particle precipitation must therefore be considered, in addition to other proposed mechanisms such as gravity waves and soft electron precipitation, as an important source of heat for Jupiter's thermosphere.     

苹果套纸罩对防止果实日灼的效应

试验结果表明，“嘎拉”和“乔纳金”树冠外围果实套纸罩可减弱果实受光强度2／3左右，生长季晴天果实日表面最高温度降低7℃以上，果实日灼率由45％左右降为7％～11％左右。苹果果实日灼易发区在其树冠西南面应适当多留内膛果和半遮荫果，外围裸露果则可套纸罩保护，时间以5月中下旬进行为宜。     

Volatile components of the cyanobacterium Oscillatoria perornata (Skuja).

Volatile compounds were identified from unialgal continuous cultures of the cyanobacterium Oscillatoria perornata. Steam distillates of the unialgal cultures were continuously extracted with pentane, and the pentane extracts were analyzed by GC-MS. Retention indices and mass spectral data were used to identify 15 components. Relative amounts of individual components were expressed as percent peak area relative to total peak area. The main volatile components were heptadecane (57.0%), 2-methylisoborneol (29.4%), and benzaldehyde (1.2%). Together with the previously known 2-methylisoborneol, which is the major cause of the musty off-flavor problem in catfish farming operations in Mississippi, other components identified were dimethyl disulfide (1.0%), dimethyl trisulfide (0.5%), and benzothiazole (0.6%). These compounds and their organoleptic characteristics are discussed in relation to their possible contributions to cultured catfish off-flavor problems.     

Honey with high levels of antioxidants can provide protection to healthy human subjects

Free radicals and reactive oxygen species (ROS) have been implicated in contributing to the processes of aging and disease. Humans protect themselves from these damaging compounds, in part, by absorbing antioxidants from high-antioxidant foods. This report describes the effects of consuming 1.5 g/kg body weight of corn syrup or buckwheat honey on the antioxidant and reducing capacities of plasma in healthy human adults. The corn syrup treatment contained 0.21 +/- 0.06 mg of phenolic antioxidants per gram, and the two buckwheat honey treatments contained 0.79 +/- 0.02 and 1.71 +/- 0.21 mg of phenolic antioxidants per gram. Following consumption of the two honey treatments, plasma total-phenolic content increased (P < 0.05) as did plasma antioxidant and reducing capacities (P < 0.05). These data support the concept that phenolic antioxidants from processed honey are bioavailable, and that they increase antioxidant activity of plasma. It can be speculated that these compounds may augment defenses against oxidative stress and that they might be able to protect humans from oxidative stress. Given that the average sweetener intake by humans is estimated to be in excess of 70 kg per year, the substitution of honey in some foods for traditional sweeteners could result in an enhanced antioxidant defense system in healthy adults.     

Interactions between soil micro- and mesofauna and plants in an ecofarming system

Interactions between crops and soil micro- and mesofauna within the root zone were investigated under field conditions on sandy loam on a larger spatial scale and in columns in the laboratory on a smaller spatial scale. During the vegetation period of summer wheat from April to July 1999 soil samples were taken monthly directly from the root zone within plant rows and between plant rows hardly penetrated by roots. Abundances of Enchytraeidae, Collembola, soil flagellates, enzyme activities and contents of total carbon and nitrogen were determined. Additionally, a laboratory experiment was carried out with soil columns. Soil from the field was defaunated and inoculated with soil fauna (Enchytraeidae, Collembola, earthworms) in different combinations. Furthermore, summer wheat was sown. Enzyme activities, soil flagellate abundance and contents of total carbon and nitrogen were measured after 2, 6 and 14 weeks. Our field results revealed considerable interactions between plant roots, sampling date and soil layer affecting Enchytraeidae and Collembola. Within plant rows flagellate numbers correlated higher with N_t and C_t than between plant rows. In the laboratory close relationships between soil fauna as well as enzyme activities and nutrients contents were found within the root zone.