Abstract:  Producing antifreeze proteins is one of the most important mechanisms underlying insect cold tolerance. However, detecting the activity of antifreeze proteins still has some difficulties, especially when only a few of insect samples are available from fields. In order to explore if differential scanning calorimetry (DSC) can be used to detect thermal hysteresis activity (THA) of the total protein in insects, the THA of the total protein and hemolymph from Tenebrio molitor larvae was detected by DSC. The results showed that the THA of the total protein (0.49-0.98℃) is lower than that of hemolymph (2.54-4.34℃) in T. molitor. In addition, we collected three overwintering insect species (Lymantria dispar larvae, Yponomeuta evonymallus eggs and Ips subelongatus adults) in the Daxing’anling Forest Region in Inner Mongolia, and then prepared their total protein. Using DSC, the THA of the total protein from the three insect species were respectively analyzed. The results showed that each of them had thermal hysteresis activity, and the THA was 0.34-0.43℃ for L. dispar, 0.35-0.42℃ for Y. evonymallus and 0.37-0.40℃ for I. subelongatus, suggesting that the three insect species can improve their cold tolerance through producing antifreeze proteins. This study indicates that the differential scanning calorimetry is feasible to identify whether one insect species contains antifreeze proteins through detecting thermal hysteresis activity of the total protein.

Key words: Tenebrio molitor, total protein, antifreeze proteins, thermal hysteresis activity, differential scanning calorimetry