应用差示扫描量热法检测昆虫总蛋白的热滞活性

Detecting thermal hysteresis activity of the total protein in insects with differential scanning calorimetry

产生抗冻蛋白是寒带昆虫抵御低温的重要机制之一,但检测其活性仍存在一些困难,尤其对于个体较小的昆虫样品。为了探索差示扫描量热法是否适于检测昆虫总蛋白的热滞活性,本研究利用差示扫描量热法对黄粉虫Tenebrio molitor幼虫的总蛋白和血淋巴分别进行了热滞活性检测。结果表明:黄粉虫总蛋白的热滞活性(0.49～0.98℃)要低于血淋巴(2.54～4.34℃)。通过这种方法,进一步检测了3种在内蒙古大兴安岭林区采集到的越冬昆虫:稠李巢蛾Yponomeuta evonymallus幼虫、舞毒蛾Lymantria dispar卵和落叶松八齿小蠹Ips subelongatus成虫。结果发现,它们都存在热滞活性,其中稠李巢蛾的热滞活性为0.34～0.43℃,舞毒蛾的热滞活性为0.35～0.42℃,落叶松八齿小蠹的热滞活性为0.37～0.40℃,说明这3种昆虫能以产生抗冻蛋白的方式作为越冬策略之一。本研究表明通过差示扫描量热法检测昆虫总蛋白是否存在热滞活性来判断抗冻蛋白的存在是可行的。

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, O. 35 - 0.42℃ for Y. evonymallus and 0.37 - 0.40℃ for L 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.