1. Look for the cold-tolerant or non-cold-tolerant natural mutant of this species (if this species is easy to be artificially mutated, it can also be artificially mutated), extract the cell mRNA of two animals, and see the difference of gene expression profile between cold-tolerant or non-cold-tolerant individuals and normal individuals.
Nowadays, a lazy method is widely adopted. The genome of animal cells was extracted and cut into several fragments, and then the reporter gene was connected to prepare expression plasmid and transferred to animal cells. Then use the method of low temperature induction. If a reporter gene is expressed in cells, it proves that a dna sequence connected with the reporter gene can be induced to express at low temperature, and the gene may be the promoter of antifreeze gene.