Isolation and characterization of cDNA clones encoding antifreeze proteins of the pyrochroid beetle Dendroides canadensis

Temporal differences in the expression of Dendroides canadensis antifreeze protein (DAFP) are indicated from seasonal comparison of dafp-1 transcript level, thermal hysteresis activity and temperature changes. DAFP-1 transcript abundance correlates with the thermal hysteresis activity level in late fall/early winter and appears to follow overall seasonal temperature changes with peak transcript levels occurring in December. A cDNA library created from December larvae yielded clones encoding a set of novel putative DAFPs. Some of the cDNA clones isolated display significant divergence at the primary amino acid level, yet, maintain conservation of key residues that are presumably important for structure and function of antifreeze proteins in this cold-hardy organism. Seasonal analysis of two dafps (dafp-1 and dafp-7) revealed differences on the transcriptional level, suggesting that DAFPs may serve somewhat different functions.