Adaptation of insects to extremely cold winters and extremely hot summers in Siberia

The present project is focused on adaptations which make insects able to survive the extremely cold winters and hot summers in inner Siberia. The studies will compare the features of insects in Yakutia with those of Scandinavia, preferably by comparing fe atures of the same species. The project will be carried out in collaboration with Dr. Natalia G. Li at Inst. of Biological Problems of Cryolithozone in Yakutsk. Since freezing tolerance usually offers the strongest cold-hardiness, the frequency of fr eeze-tolerant versus freeze-avoiding species in Yakutia will be compared to that in Scandinavia. The possible shift within species from freeze-avoidance in Scandinavia to freezing tolerance in Yakutia will be looked into. The cryoprotective role of el evated polyol levels in freeze-tolerant insects will be studied. We will look into the possible role of vitrification as a cryoprotective mechanism, and try to identify sugars and proteins that promote vitrification. Freeze-tolerant insects have gener ally a highly water permeable body wall, which may cause problems during the prevailing extremely hot and dry summers. We will study the water balance of summer and winter acclimated Siberian freeze-tolerant insects to see if they acclimate seasonally. In freeze-avoiding insects we will study the role of elevated polyol levels, but special emphasis will be given to antifreeze proteins (AFPs). The amino acid sequence of the highly active AFPs from Rhagium inquisitor beetles in Yakutia will be compared to that of the same species in Scandinavia (for which the sequence is determined in our lab.), and their three dimensional structures will be determined on NMR. Also AFPs of other species will be studied. It is also possible that highly supercooled fr eeze-avoiding insects are protected by vitrification. We will use DSC to study glass transition in highly supercooled Yakutian insects and search for vitrification promoting agents.