Ozone sensitivity of Phaseolus vulgaris in relation to cultivar differences,growth stage and growing conditions

Exposure of Phaseolus vulgaris cv. Lit to ambient ozone caused a 14% pod yield reduction in 1994. This yield loss was assessed by comparing plants that were protected against ozone by treatment with EDU (ethylenediurea) with unprotected plants, both cultivated in pots with a continuous water supply. The plants had experienced an AOT40 of 8135 ppb.h during their growth. However, plant response to ozone depends on a large number of environmental and plant-specific conditions. Visible injury increased mainly after flowering and was much less severe on soil-grown bean cultivars (Lit, Stella and Groffy) not receiving additional water. Ozone fumigations in closed chambers before or after flowering proved that the growth stage during which the plants are exposed also plays a very important role with regard to injury development. Plants seem to be more susceptible during the generative growth stage and the relative cultivar sensitivity was related to the developmental stage during fumigation. However with regard to yield effects the timing of the ozone exposure seems to be less important.     

堆渣边坡生态棒护坡措施的水土保持效益

[目的]探究堆渣边坡生态棒防护措施的综合防护效果,为露天采石场裸露边坡的生态修复提供依据。[方法]利用人工降雨模拟试验,收集不同降雨强度下地表层和矿渣层的产流量、产沙量,并建立综合贡献度模型。[结果]随着坡度的增加地表层的径流总量和泥沙总量呈递增趋势,而矿渣层的径流总量和泥沙总量呈递减趋势,与径流总量相比泥沙总量变化趋势不明显;对照组与生态棒防护措施下,地表层的产流—产沙相关性均高于矿渣层;当降雨强度为30和120mm/h时,生态棒防护边坡在坡度为15°时具有较佳的防护效果,当降雨强度为60mm/h时,径流量和泥沙量受坡度变化的影响不显著。[结论]生态棒防护措施具有拦蓄坡面径流和泥沙的功能,与对照组相比可以更有效地防治坡面水土流失。     

翻转犁限位块形状的反求分析与设计

以JD型液压翻转犁为模型机 ,运用反求工程技术 ,对其限深轮换位机构的限位块进行反求分析和研究 ,建立了其结构形状优化设计的数学模型 ,为零件的形状优化提供了一种新的思路和方法。同时将反求结果用于1LF— 335液压翻转犁 ,该犁已投入批量生产 ,限位块工作性能良好。     

Development of the polysaccharidic matrix in biocrusts induced by a cyanobacterium inoculated in sand microcosms

Soil inoculation with cyanobacteria (cyanobacterization) is a biotechnological method widely studied to improve soil quality and productivity. During their growth on soil, cyanobacteria excrete exopolysaccharides (EPSs) which glue trichomes to soil particles, in a three-dimensional extracellular polymeric matrix. EPS productivity is an important screening parameter to select proficient inoculants and is affected by growth conditions and abiotic stresses. In this study, we evaluated the capability of the cyanobacterium Schizothrix cf. delicatissima AMPL0116 to form biocrusts when inoculated in sand microcosms under stressing conditions, and the characteristics of the synthesized polymeric matrix. In parallel, we evaluated the characteristics of exopolysaccharidic exudates of the strain when grown in liquid culture, under optimal growth setting. Our results pointed out at significant differences of the exopolymers produced in the two conditions in terms of monosaccharidic composition and molecular weight distribution, and proved the capability of S. cf. delicatissima AMPL0116 to form stable bioaggregates on sandy soils.     

Susceptibility of cocooned pupae and adults of the parasitoid <Emphasis Type="Italic">Microplitis mediator</Emphasis> to selected insecticides

The braconid parasitoid Microplitis mediator (Haliday) is a key natural enemy of the cabbage moth, Mamestra brassicae (L.), in Europe. In the context of an Integrated Pest Management approach, the use of selective insecticides is essential for the conservation of naturally occurring beneficial arthropods. The present laboratory study investigated the side effects of six insecticides applied at recommended field rates on adults and cocooned pupae of M. mediator. Male and female parasitoids were paired in drum cells contaminated with dry residues of insecticides. Besides lethal effects after 24 h, parasitization capacity and longevity of the surviving parasitoids was evaluated. Lethal effects on cocooned pupae were also investigated by assessing adult emergence from treated cocoons. Pirimicarb caused 100% adult mortality after 24 h, whereas the other tested insecticides caused no direct toxic effects. However, sub-lethal effects in terms of reduced parasitization activity, percentage of parasitism or female longevity were found for flonicamid, pymetrozine, spinosad and thiacloprid. Spirotetramat shortened only male longevity. Adult emergence from treated cocoons was reduced only by flonicamid and pymetrozine.     

‘Plantibodies’: a flexible approach to design resistance against pathogens

Engineering resistance against various diseases and pests is hampered by the lack of suitable genes. To overcome this problem we started a research program aimed at obtaining resistance by transfecting plants with genes encoding monoclonal antibodies against pathogen specific proteins. The idea is that monoclonal antibodies will inhibit the biological activity of molecules that are essential for the pathogenesis. Potato cyst nematodes are chosen as a model and it is thought that monoclonal antibodies are able to block the function of the saliva proteins of this parasite. These proteins are, among others, responsible for the induction of multinucleate transfer cells upon which the nematode feeds. It is well documented that the ability of antibodies to bind molecules is sufficient to inactivate the function of an antigen and in view of the potential of animals to synthesize antibodies to almost any molecular structure, this strategy should be feasible for a wide range of diseases and pests.Antibodies have several desirable features with regard to protein engineering. The antibody (IgG) is a Y-shaped molecule, in which the domains forming the tips of the arms bind to antigen and those forming the stem are responsible for triggering effector functions (Fc fragments) that eliminate the antigen from the animal. Domains carrying the antigen-binding loops (Fv and Fab fragments) can be used separately from the Fc fragments without loss of affinity. The antigen-binding domains can also be endowed with new properties by fusing them to toxins or enzymes. Antibody engineering is also facilitated by the Polymerase Chain Reaction (PCR). A systematic comparison of the nucleotide sequence of more than 100 antibodies revealed that not only the 3′-ends, but also the 5′-ends of the antibody genes are relatively conserved. We were able to design a small set of primers with restriction sites for forced cloning, which allowed the amplification of genes encoding antibodies specific for the saliva proteins ofGlobodera rostochiensis. Complete heavy and light chain genes as well as single chain Fv fragments (scFv), in which the variable parts of the light (V_L) and heavy chain (V_H) are linked by a peptide, will be transferred to potato plants. A major challenge will be to establish a correct expression of the antibody genes with regard to three dimensional folding, assembly and intracellular location.     

Effects of paraquat treatment on fish transaminase molecular subforms

The effects of paraquat (PQ; 1,1′-dimethyl-4,4′-bipyridylium dichloride) treatment were investigated in carp, silver carp and wels. The serum glutamic-oxalacetic transaminase (GOT; L-aspartate: 2-oxoglutarate aminotransferase, EC 2.6.1.1.) level was enhanced by 50% at 1 ppm exposure and by 100% at 10 ppm exposure in all species, and there was a change in the distribution of the molecular subforms of GOT in the liver and heart. The activities of the individual subforms decreased with increasing PQ concentration or after a longer exposure. In some cases, one of the subforms was no longer present in the liver. An increased serum GOT activity, a decreased enzyme activity in different organs and the disappearance of molecular subform indicate tissue damage.     

Sri Lankan reservoir fishery: a case for introduction of a co-management strategy

The inland fisheries of Sri Lanka are essentially artisanal on most of the reservoirs in the country. The annual inland fish production declined dramatically after 1990, when state patronage for the development of the inland fisheries was discontinued for 4 years. This decline was shown to be a result of growth overfishing of the two dominant cichlid species which accounted for over 90% of landings. This was a result of using small mesh ( < 6.9 cm) gillnets in the absence of the State-sponsored monitoring procedure in the fishery after 1990. This indicates that it is necessary to monitor inland fisheries management in Sri Lanka through a centralized authority in the current situation. However, in some Sri Lankan reservoirs, fishing communities can be categorized as 'organized' because they collectively make decisions to define procedures for the rational exploitation of the fishery resources. In reservoirs with 'organized' fishing, the communities themselves have developed mechanisms to regulate the landing sizes of dominant cichlid fish species through community-based fisheries management strategies. In such reservoirs, over-exploitation of fish stocks was not evident, even after 1990, when state-sponsored monitoring procedures were suspended. Based on these observations, an alternative approach is recommended for the management of Sri Lankan reservoir capture fisheries in which the Government and resource-users have equal responsibilities in the management of the resources.     

Pharmacokinetics of a single intravenous dose of marbofloxacin in adult donkeys

Six donkeys each received 2 mg/kg marbofloxacin as a 10 per cent aqueous solution administered intravenously. Principal pharmacokinetic parameters were determined and two efficacy indices were computed by using pharmacokinetic parameters and selected mic90 values of marbofloxacin against pathogenic equine strains to predict the efficacy of the drug at this dose. The pharmacokinetics of marbofloxacin in donkeys was characterised by a large mean volume of distribution at a steady state (1.15 [0.09] l/kg) and a long mean (sd) elimination half-life of 9.24 (1.96) hours. It was also characterised by a relatively slow total body clearance of 0.10 (0.02) l/kg/hour, slower than in horses. Using mic90 values of marbofloxacin against pathogenic equine strains with a daily dose of 2 mg/kg, appropriate values of efficacy indicators were obtained only for Enterobacteriaceae. Daily intravenous doses of 0.33, 2.62 and 20 mg/kg were calculated for evaluation in clinical trials of infections due to Enterobacteriaceae, Staphylococcus aureus and Streptococci, respectively.     

Case report: congenital myoclonus in a German Holstein calf

A female German Holstein calf was not able to stand up after birth. Resting the animal was lying in normal position and could lift its head. Sensory stimuli like auditory or tactile impulses induced myoclonic jerking of the whole body. Afterwards it calmed down quickly. The signs observed correspond to the clinical findings of congenital myoclonus in poll Hereford calves. The pathological examination revealed no indications for changes in organs. The inbreeding coefficient of the calf was 1.56 %. The present type of congenital myoclonus in the calf examined is likely to be genetically determined, even if the point mutation in exon 2 of the glycin receptor alpha 1 gene was not confirmed.