Das Projekt "Ecotoxicology of Organotin compounds" wird/wurde ausgeführt durch: Universität Frankfurt am Main, Institut für Ökologie, Evolution und Diversität, Abteilung Aquatische Ökotoxikologie.Organotin and especially butyltin compounds are used for a variety of applications, e.g. as biocides, stabilizers, catalysts and intermediates in chemical syntheses. Tributyltin (TBT) compounds exhibit the greatest toxicity of all organotins and have even been characterized as one of the most toxic groups of xenobiotics ever produced and deliberately introduced into the environment. TBT is not only used as an active biocidal compound in antifouling paints, which are designed to prevent marine and freshwater biota from settlement on ship hulls, harbour and offshore installations, but also as a biocide in wood preservatives, textiles, dispersion paints and agricultural pesticides. Additionally, it occurs as a by-product of mono- (MBT) and dibutyltin (DBT) compounds, which are used as UV stabilizer in many plastics and for other applications. Triphenyltin (TPT) compounds are also used as the active biocide in antifouling paints outside Europe and furthermore as an agricultural fungicide since the early 1960s to combat a range of fungal diseases in various crops, particularly potato blight, leaf spot and powdery mildew on sugar beet, peanuts and celery, other fungi on hop, brown rust on beans, grey moulds on onions, rice blast and coffee leaf rust. Although the use of TBT and TPT was regulated in many countries world-wide from restrictions for certain applications to a total ban, these compounds are still present in the environment. In the early 1970s the impact of TBT on nontarget organisms became apparent. Among the broad variety of malformations caused by TBT in aquatic animals, molluscs have been found to be an extremely sensitive group of invertebrates and no other pathological condition produced by TBT at relative low concentrations rivals that of the imposex phenomenon in prosobranch gastropods speaking in terms of sensitivity. TBT induces imposex in marine prosobranchs at concentrations as low as 0,5 ng TBT-Sn/L. Since 1993, for the littorinid snail Littorina littorea a second virilisation phenomenon, termed intersex, is known. In female specimens affected by intersex the pallial oviduct is transformed of towards a male morphology with a final supplanting of female organs by the corresponding male formations. Imposex and intersex are morphological alterations caused by a chronic exposure to ultra-trace concentrations of TBT. A biological effect monitoring offers the possibility to determine the degree of contamination with organotin compounds in the aquatic environment and especially in coastal waters without using any expensive analytical methods. Furthermore, the biological effect monitoring allows an assessment of the existing TBT pollution on the basis of biological effects. Such results are normally more relevant for the ecosystem than pure analytical data. usw.
Das Projekt "Emmy Noether-Nachwuchsgruppen, Development and risk assessment of transgenic environmentally-friendly insect pest control methods for fruit flies and mosquitoes" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Universität Gießen, Institut für Phytopathologie und Angewandte Zoologie, Abteilung Angewandte Entomologie.Various species of pest insects cause substantial damage to agriculture every year, or transmit deadly diseases to animals and humans. A successful strategy to control pest insect populations is based on the Sterile Insect Technique (SIT), which uses the release of mass-reared, radiation sterilized male insects to cause infertile matings and thus reduce the pest population level. However, irradiation is not applicable to every insect species. Thus, new strategies based on genetic modifications of pest insects have been developed or are currently under investigation.The goal of the proposed research is to improve the development and ecological safety of genetically engineered (GE) insects created for enhanced biological control programs, including the SIT and new strategies based on conditional lethality. A major concern for GE insect release programs is transgene stability, and maintenance of their consistent expression. Transgene loss or intra-genomic movement could result in loss of strain attributes, and may ultimately lead to interspecies movement resulting in ecological risks. To address potential transgene instability, a new transposon vector that allows post-integration immobilization will be tested in the Mediterranean, Mexican and Oriental fruit fly tephritid pest species. In addition, the system will be established in the mosquito species Aedes and Anopheles - carriers of dengue and malaria.Random genomic insertion is also problematic for GE strain development due to genomic position effects that suppress transgene expression, and insertional mutations that negatively affect host fitness and viability. Diminished transgene expression could result in the unintended survival of conditional lethal individuals, or the inability to identify them. To target transgene vectors to defined genomic insertion sites having minimal negative effects on gene expression and host fitness, a recombinase-mediated cassette exchange (RMCE) strategy will be developed that. RMCE will also allow for stabilization of the target site, will be tested in tephritid and mosquito species, and will aid to the development of stabilized target-site strains for conditional lethal biocontrol. This will include a molecular and organismal evaluation of an RNAi-based lethality approach. Lethality based on an RNAi mechanism in the proposed insects would increase the species specificity and having multiple targets for lethality versus one target in existing systems. By seeking to improve transgene expressivity and stabilization of transposon-based vector systems, this proposal specifically addresses issues related to new GE insects by reducing their unintended spread after field release, and by limiting the possibilities for transgene introgression.
Das Projekt "Sonderforschungsbereich (SFB) 564: Nachhaltige Landnutzung und ländliche Entwicklung in Bergregionen Südostasiens; Sustainable Land Use and Rural Development in Mountainous Regions of Southeast Asia, A 1.3: Potential and constraints of participatory research approaches for sustainable development in mountainous regions of Southeast Asia: Addressing issues of scale - Phase 3" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft / Ministry of Science and Technology (MOST) / National Research Council of Thailand (NRCT). Es wird/wurde ausgeführt durch: Universität Hohenheim, Institut für Sozialwissenschaften des Agrarbereichs, Fachgebiet Landwirtschaftliche Kommunikations- und Beratungslehre.In this overarching subproject the potential and limits of participatory research approaches are investigated. Institutional arrangements that are conducive to integrating local stakeholders (female and male farmers, extension services, state agencies and NGOs) into the research process are developed and tested. Research focuses on the question which form and intensity of participation in which phases of the research process in different disciplines are feasible and beneficial. An analytical framework developed during the first phase has been applied for comparative assessment of subprojects in the SFB 564 with regard to participatory elements in the research process. It has also successfully been tested in other research programs and is now available for wider application in the analysis of participation in agricultural and environmental research programs. The analysis of the wider social, cultural and institutional context for participatory approaches in research and extension organizations was another focus of the second phase. The case of Vietnam, in particular, has shown how strongly the institutionalization of these approaches is determined by international donors and projects, but also how these are transformed in the specific national, regional and local context. Research in the second phase has placed strong emphasis on a more systematic collection, validation and integration of local knowledge in the research process. It has been proven that blending local and scientific knowledge cannot only improve the quality of research, but also open up new research trajectories in an innovative and cost-effective manner. Based on the experience with participatory approaches at the local level and the analysis of participation as an institutional innovation process in research and extension organizations during phases 1 and 2 of subproject A1, research in A1.3 will determine the prerequisites for successfully scaling up and out participatory approaches in the field of recording and validation of local knowledge, participatory technology development and the adaptation, dissemination and use of technical and institutional innovations in the study areas of northern Thailand and northern Vietnam. The question is how to combine the intensity and quality of micro-scale participatory approaches with the need for (1) scaling up to reach higher levels of decision-making (political dimension) and address wider regional problems (geographical dimension) and (2) scaling out to reach a higher number of farmers and other potential beneficiaries and to link research with extension services and private sector initiatives.