Validation of the performance of a GMO multiplex screening assay based on microarray detection

A new screening method for the detection and identification of GMO, based on the use of multiplex PCR followed by microarray, has been developed and is presented. The technology is based on the identification of quite ubiquitous GMO genetic target elements first amplified by PCR, followed by direct hybridisation of the amplicons on a predefined microarray (DualChip® GMO, Eppendorf, Germany). The validation was performed within the framework of a European project (Co-Extra, contract no 007158) and in collaboration with 12 laboratories specialised in GMO detection. The present study reports the strategy and the results of an ISO complying validation of the method carried out through an inter-laboratory study. Sets of blind samples were provided consisting of DNA reference materials covering all the elements detectable by specific probes present on the array. The GMO concentrations varied from 1% down to 0.045%. In addition, a mixture of two GMO events (0.1% RRS diluted in 100% TOPAS19/2) was incorporated in the study to test the robustness of the assay in extreme conditions. Data were processed according to ISO 5725 standard. The method was evaluated with predefined performance criteria with respect to the EC CRL method acceptance criteria. The overall method performance met the acceptance criteria; in particular, the results showed that the method is suitable for the detection of the different target elements at 0.1% concentration of GMO with a 95% accuracy rate. This collaborative trial showed that the method can be considered as fit for the purpose of screening with respect to its intra- and inter-laboratory accuracy. The results demonstrated the validity of combining multiplex PCR with array detection as provided by the DualChip® GMO (Eppendorf, Germany) for the screening of GMO. The results showed that the technology is robust, practical and suitable as a screening too

The impact of inflation risk on forward trading and production

This paper examines the behavior of a competitive firm that faces joint price and inflation risk. Given that the price risk is negatively correlated with the inflation risk in the sense of expectation dependence, we show that the firm optimally opts for an over-hedge (under-hedge) if the firm’s coefficient of relative risk aversion is everywhere no greater (no smaller) than unity. We show further that banning the firm from forward trading may induce the firm to produce more or less, depending on whether the price risk premium is positive or negative, respectively. While the price risk premium is unambiguously negative in the absence of the inflation risk, it is not the case when the inflation risk prevails. In contrast to the conventional wisdom, forward hedging needs not always promote production should firms take inflation seriously.info:eu-repo/semantics/publishedVersio

Symmetric and asymmetric action integration during cooperative object manipulation in virtual environments

Cooperation between multiple users in a virtual environment (VE) can take place at one of three levels. These are defined as where users can perceive each other (Level 1), individually change the scene (Level 2), or simultaneously act on and manipulate the same object (Level 3). Despite representing the highest level of cooperation, multi-user object manipulation has rarely been studied. This paper describes a behavioral experiment in which the piano movers' problem (maneuvering a large object through a restricted space) was used to investigate object manipulation by pairs of participants in a VE. Participants' interactions with the object were integrated together either symmetrically or asymmetrically. The former only allowed the common component of participants' actions to take place, but the latter used the mean. Symmetric action integration was superior for sections of the task when both participants had to perform similar actions, but if participants had to move in different ways (e.g., one maneuvering themselves through a narrow opening while the other traveled down a wide corridor) then asymmetric integration was superior. With both forms of integration, the extent to which participants coordinated their actions was poor and this led to a substantial cooperation overhead (the reduction in performance caused by having to cooperate with another person)

Soyuretox, an intrinsically disordered polypeptide derived from soybean (Glycine max) ubiquitous urease with potential use as a biopesticide

Ureases from different biological sources display non-ureolytic properties that contribute to plant defense, in addition to their classical enzymatic urea hydrolysis. Antifungal and entomotoxic effects were demonstrated for Jaburetox, an intrinsically disordered polypeptide derived from jack bean (Canavalia ensiformis) urease. Here we describe the properties of Soyuretox, a polypeptide derived from soybean (Glycine max) ubiquitous urease. Soyuretox was fungitoxic to Candida albicans, leading to the production of reactive oxygen species. Soyuretox further induced aggregation of Rhodnius prolixus hemocytes, indicating an interference on the insect immune response. No relevant toxicity of Soyuretox to zebrafish larvae was observed. These data suggest the presence of antifungal and entomotoxic portions of the amino acid sequences encompassing both Soyuretox and Jaburetox, despite their small sequence identity. Nuclear Magnetic Resonance (NMR) and circular dichroism (CD) spectroscopic data revealed that Soyuretox, in analogy with Jaburetox, possesses an intrinsic and largely disordered nature. Some folding is observed upon interaction of Soyuretox with sodium dodecyl sulfate (SDS) micelles, taken here as models for membranes. This observation suggests the possibility for this protein to modify its secondary structure upon interaction with the cells of the affected organisms, leading to alterations of membrane integrity. Altogether, Soyuretox can be considered a promising biopesticide for use in plant protection

Lichens facilitate seedling recruitment in alpine heath

Abstract Questions How do mat thickness, physical structure and allelopathic properties of terricolous mat-forming lichens affect recruitment of vascular plants in dwarf-shrub and lichen heath vegetation?. Location The mountains of Dovrefjell, central Norway. Methods In autumn, seeds of ten vascular plant species were collected and sown in a common garden experiment with mats of six lichen species and bare-soil controls as experimental treatments. We recorded growing season soil temperature and moisture, and seedling recruitment and growth after one year. The effect of lichen secondary compounds on germination was tested in a growth chamber experiment and compared to the lichen-plant interactions detected under field conditions. Results The lichen mats buffered extreme soil temperatures and soil drying in dry weather, with soils below the thickest mats (Cladonia stellaris and C. rangiferina) experiencing the lowest temperature fluctuations. Seedling recruitment and seedling growth in the field and seed germination in the lab were species-specific. Seedling recruitment rates were overall higher within lichen mats than on bare soil, but the c. 6.5 cm thick mats of C. stellaris reduced recruitment of many species. The lab experiment suggested no overall strong effect of lichen allelopathy on seed germination, and effects on seed germination were only moderately correlated with the lichen-plant interactions observed for seedling recruitment in the field. Conclusions In harsh environments like alpine dwarf-shrub and lichen heaths, the presence of lichens and the resulting amelioration of the microclimate seems more important for vascular plant recruitment than are allelopathic effects often reported in lab experiments. We might therefore expect most terricolous lichens, depending on the plant species in focus, to facilitate rather than hamper the early stages of plant recruitment into lichen-dominated arctic-alpine heath vegetation. This article is protected by copyright. All rights reserved.Peer reviewe