Differential Expression of Two Antifreeze Proteins in the Desert Beetle Anatolica Polita (Coleoptera: Tenebriondae): Seasonal Variation and Environmental Effects

Antifreeze proteins (AFPs) can inhibit and modify the growth of ice crystals. Two antifreeze protein genes, Apafp 752 and Apafp 914, were cloned from the desert beetle Anatolica polita (Coleoptera: Tenebriondae), and they shared 61.3% similarity at the amino acid level. Apafp 752 also contained one variation in the most conserved TCT motif of beetle AFPs. Apafp 752 and Apafp 914 mRNAs had similar seasonal expression pattern. Both were stimulated by cold stress, but they expressed slightly differentially with Apafp 752 being more sensitive to cold stress than Apafp 914, and no more sensitive to desiccation stress than Apafp 914. The thermal hysteresis activity (THA) in the beetle's hemolymph followed approximately the patterns of mRNA seasonal expression and expression upon environmental stress, with a time lag. Summer adults of the desert beetle also express mRNA of Apafp 752 and Apafp 914, and exhibit some hemolymph THA, suggesting other likely function of these proteins beyond antifreeze.