Impact of an Urban Environment on Trace Element Concentrations in Domestically Produced Lettuce (<Emphasis Type="Italic">Lactuca sativa L.</Emphasis>)

Urban horticulture is gaining more and more attention in the context of sustainable food supply. Yet, cities are exposed to (former) industrial activities and traffic, responsible for emission of contaminants. Trace elements were monitored in soils located in the urban environment of Ghent (Belgium) and 84 samples of Lactuca satica L. lettuce grown on it. The effects of cultivation in soil versus trays, neighbouring traffic and washing of the lettuce before consumption were studied. The 0–30 cm top layer of soils appeared heterogenic in composition and enriched in Co, Cd, Ni and Pb within 10 m from the nearest road. Yet, no similar elevated concentrations could be found in the crops, except for As. Besides uptake from the roots, the presence of trace elements in the plants is also caused by the atmospheric deposition of airborne particulate matter on the leaf surface. Correlation analysis and principal component analysis (PCA) revealed that this latter transport pathway might particularly be the case for Pt, Pd and Rh. Concentrations of Cd did not exceed the 0.2 mg kg^?1 (fresh weight) threshold for Cd in leafy vegetables set by the European Commission. Measurements to reduce the health risks include the washing of lettuce, which effectively reduced the number of samples trespassing the maximum Pb level of 0.3 mg kg^?1 (fresh weight). Also, cultivation in trays resulted in a lower As content in the plants. Taking into account a vigilance on crop selection, cultivation substrate and proper washing before consumption are considered essential steps for safe domestic horticulture in urban environments.     

Soil erosion and runoff: The need to rethink mitigation strategies for sustainable agricultural landscapes in western Europe

Agricultural landscapes that are intensively farmed, as in western Europe, face the challenge of a transition to more sustainable systems. Although erosion rates are relatively low in western Europe, the agricultural landscape is confronted by the need to mitigate the off-site impacts of erosion. An important challenge is that of disrupting connectivity between runoff and sediment sources, often farmers' fields, and freshwater systems or local communities. Mitigation strategies should include monitoring of erosion rates and off-site impacts and a mix of engineered and alternative measures such as buffer strips and retention ponds. Also needed are supportive government policies and actions including awareness of institutional memory problems and the promotion of farmer education. For the future, the risk of climate change must be appreciated and built into the planning of comprehensive mitigation strategies. Our perspective is that the overall aim should be a ‘sustainable agricultural landscape’ and not simply a reduction of erosion and runoff on farmers' fields.     

Zum Problem der Nebenwirkungen von Insektiziden in den Agrocoenosen

Zusammenfassung Die Nebenwirkung von Insektiziden auf die Lebensgemeinschaften der Kulturen ist desto tiefer und durchgreifender, um je dauerhaftere Kulturen es sich handelt. Obwohl in den Agrocoenosen Selbstregulation und Gleichgewicht fehlen, bestehen hier doch bedeutende quantitative Zusammenhänge zwischen Schädlingen und ihren Räubern und Parasiten. Diese Zusammenhänge werden an Beispielen von Hauptschädlingen der Hackfrüchte dargestellt.Es wird vorgeschlagen, schon bei der Prüfung von Insektiziden die Wirkungsweise des Insektizides auf die wichtigsten natürlichen Feinde von Schädlingen zu untersuchen.

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Summary In the agrocoenoses the intensity of the side effects of insecticides is in proportion to the degree of permanency of the cultures. Although the agrocoenoses do not represent a self-regulated and balanced ecological unit, there are, however, quantitative correlations between the pests and their predators and parasites. These interrelations are demonstrated by examples from the main pests of the root crops.It is suggested that the effects of insecticides on the most important natural enemies of the pests be examined already in the testing stage of the insecticides.

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Résumé Les effects secondaires des insecticides sur les agrocénoses sont d'autant plus importants et actifs qu'il s'agit de cultures permanentes. Bien que des régulations spontanées et l'equilibre manquent dans les agrocénoses, il existe done d'importants rapports quantitatifs entre les insectes nuisibles et leurs prédateurs et leurs parasites. Ces rapports seront illustrés par des exemples des principaux insectes nuisibles aux plantes sarclées.On propose d'étudier, dès la mise à l'essai des différents insecticides, le mode d'action de chaque insecticide sur les ennemis naturels les plus importants des insectes nuisibles.

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mit 5 Fig.

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Vortrag, gehalten am 4. September 1967 auf dem VI. Internationalen Pflanzenschutzkongress in Wien.     

Chlorophyll <Emphasis Type="Italic">a</Emphasis> fluorescence,under half of the adaptive growth-irradiance,for high-throughput sensing of leaf-water deficit in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> accessions

Background

Non-invasive and high-throughput monitoring of drought in plants from its initiation to visible symptoms is essential to quest drought tolerant varieties. Among the existing methods, chlorophyll a fluorescence (ChlF) imaging has the potential to probe systematic changes in photosynthetic reactions; however, prerequisite of dark-adaptation limits its use for high-throughput screening.

Results

To improve the throughput monitoring of plants, we have exploited their light-adaptive strategy, and investigated possibilities of measuring ChlF transients under low ambient irradiance. We found that the ChlF transients and associated parameters of two contrasting Arabidopsis thaliana accessions, Rsch and Co, give almost similar information, when measured either after ~20 min dark-adaptation or in the presence of half of the adaptive growth-irradiance. The fluorescence parameters, effective quantum yield of PSII photochemistry (Φ_PSII) and fluorescence decrease ratio (R _FD) resulting from this approach enabled us to differentiate accessions that is often not possible by well-established dark-adapted fluorescence parameter maximum quantum efficiency of PSII photochemistry (F _V/F _M). Further, we screened ChlF transients in rosettes of well-watered and drought-stressed six A. thaliana accessions, under half of the adaptive growth-irradiance, without any prior dark-adaptation. Relative water content (RWC) in leaves was also assayed and compared to the ChlF parameters. As expected, the RWC was significantly different in drought-stressed from that in well-watered plants in all the six investigated accessions on day-10 of induced drought; the maximum reduction in the RWC was obtained for Rsch (16%), whereas the minimum reduction was for Co (~7%). Drought induced changes were reflected in several features of ChlF transients; combinatorial images obtained from pattern recognition algorithms, trained on pixels of image sequence, improved the contrast among drought-stressed accessions, and the derived images were well-correlated with their RWC.

Conclusions

We demonstrate here that ChlF transients and associated parameters measured even in the presence of low ambient irradiance preserved its features comparable to that of measured after dark-adaptation and discriminated the accessions having differential geographical origin; further, in combination with combinatorial image analysis tools, these data may be readily employed for early sensing and mapping effects of drought on plant’s physiology via easy and fully non-invasive means.

     

Demodicosis in nine prairie dogs (Cynomys ludovicianus)

This case report describes the clinical signs and treatment of demodicosis in nine pet prairie dogs (Cynomys ludovicianus). Clinical records including history, clinical examination, microscopic evaluation and fungal culture of the skin lesions were available for all nine animals. In seven animals, blood was obtained for haematological and biochemical analyses. Clinical signs comprised bilaterally symmetrical alopecia extending from the middle part of the back down to the skin of the thighs and the dorsal and ventral parts of the tail. Demodex mites were found in skin scrapings from all cases. Treatment with amitraz at 250 p.p.m. resulted in resolution of lesions and hair regrowth. This is the first report of demodicosis in this species.     

Molecular genetic and physiologic background of the growth hormone-IGF-I axis in relation to breeding for growth rate and leanness in pigs

The GH-IGF-I axis is of major importance for the regulation of body growth and composition, and cellular proliferation and differentiation processes. Selective breeding aiming to improve growth rate and/or body composition is accompanied by changes of the GH-IGF-I axis. Research aiming to elucidate the genetic and physiologic mechanism(s) underlying these changes may best use single-trait selection lines. Two such pig selection lines, one for growth rate and one for high lean content, were used in experiments to investigate the mechanisms of the GH-IGF-I axis change during selection. This contribution reviews the selection-related changes in the GH-IGF-I axis as the consequences of selection for whole body growth rate or body composition and effects on local tissue growth rate. A model explaining the observed effects and consequences for the pressure on the physiology is presented. In short, selection related demand for GH induces GH synthesis until a limit is reached. After that the pulsatile GH plasma profile changes, which may also affect expression profiles of genes regulating body composition.     

Contribution to the knowledge of the families apionidae and nanophyidae (Coleoptera: Curculionoidea) from Turkey, with new records

Data are presented on the occurrence of 43 species of the family Apionidae and two species of the family Nanophyidae in Turkey based on the material obtained mainly by beating stone-fruit trees in NE Turkey. The identity and information about the three species of Apionidae —Squamapion sp.cf.bifarium (Balfour-Browne),Protapion sp.cf.ruficrus (Germar),Catapion sp.cf.seniculus (Kirby) — must be revised. The faunistic data in the present paper on almost all species add to prior knowledge on their distribution in Turkey.Hypophyes aphyllae (Peyerímhoff),Ceratapion kasbekianum (Gerstaecker),Squamapion ottonis (Wagner),S. samarense (Faust),S. phocopus (Eppelsheim),Taeniapion rufulum (Wencker),Pseudoprotapion astragali (Paykull),P. ergenense (Becker),Stenopterapion intermedium (Eppelsheim) andOxystoma fausti (Desbrochers) are reported for the first time in the Turkish fauna. http://www.phytoparasitica.org posting Nov. 8, 2001.     

防治免疫抑制性疾病的新策略

要生产出健康的鸡群很大程度上取决于传染性疾病的控制.新疫苗技术的开发或培育出能抵抗免疫抑制性疾病的转基因鸡,在技术上已成为可行,但是这在经济上尚不能令人满意.     

Expression of Marek's disease virus phosphorylated polypeptide pp38 produces splice variants and enhances metabolic activity

The phosphorylated polypeptide (pp)38 of oncogenic Marek's disease (MD) herpesvirus (MDV) is expressed during lytic infections in vivo and in vitro, but its functions have not been fully elucidated. The quail cell line QT-35, latently infected with MDV, was used to generate QTP32 in which pp38 is expressed under control of a tetracycline controlled promoter to examine possible functions of pp38. Induction of pp38 did not influence late MDV genes expression, but it enhanced mitochondrial dehydrogenase activity significantly. Two new pp38 splice variants were found in induced QTP32 cells, in additional in vitro systems and MDV-infected chickens. Differential expression of full-length pp38 and splice variants suggests that the splice variants are important during latency and perhaps transformation. Polypeptides of 40 and 20kDa were detected by Western blot using monoclonal antibody H19. These polypeptides were also produced in DF-1 cells transfected with a pp38 construct in which the splice acceptor sites had been mutated. Our results add important new information to the role of pp38 in the pathogenesis of MD. The data suggest that pp38 and the two newly described splice variants may influence metabolic activity, which may have important consequences for the understanding of latency and tumor development.