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| Circadian oscillators in behavioural rhythmicity and photoperiodism of insects |  |  Do the circadian and seasonal clocks share common molecular and cellular components? Do light and temperature cues act through the same clocks? In two model species, Pyrrhocoris apterus (Heteroptera) and Chymomyza costata (Diptera), the homologs of clock genes period and timeless are cloned and their transcription is localised in CNS by in situ mRNA hybridization and immunocytochemistry. Function of the clock genes' products is studied by using non-photoperiodic mutants, neurosurgical interventions, physiological, biochemical and molecular methods. First insight into so far unknown molecular basis of insect seasonality should be obtained in this study.
PI: M. Hodková, V. Koš?ál. more.. | | | | Physiological adaptations to cold in insects | |  What are the main mechanisms assisting insects in long-term survival at sub-zero temperatures? Whole array of physiological and analytical methods is used to reveal the roles and regulation of: (1) seasonal accumulation of low molecular weight cryoprotectants, like sugars and polyols, (2) changes in composition of phospholipids and content of cholesterol in biological membranes, and (3) maintenance of ionic transmembrane and transepithelial electrochemical potentials by active transporting systems (ATPases). Pyrrhocoris apterus (Heteroptera) serves as the main model organism. Understanding such mechanisms will allow practical applications in long-term storage of biological material, including commercial populations of beneficial insects, mutant stocks,cells and tissues.PI: V. Koš?ál, M. Hodková. more.. | | | | Environmental-stress tolerance in arthropods living in tropics and dry habitats | |  What is the evolutionary origin of physiological adaptations for dehydration and cold tolerance? Do such adaptations overlap? Water balance, osmotic properties of body liquids, cuticular permeability for water, respiration rates and several parameters of cold tolerance are studied in several arthropod species (beetle Stenotarsus rutundus from Panama, insect storage-pests originating from tropics, terrestrial isopods). Knowledge obtained may help us to understand the potential for spreading and colonisation of new habitats in different arthropods, including insect pests. PI: O. Nedvěd, V. Koš?ál more.. | | |
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