Study of screening for defensin genes in scallop by improved rapid amplification of cDNA ends

Objective To screen AMP genes with improved 5′ RACE,to find out a feasible method for screening AMP genes from scallop based on gene homology.Methods Total RNA was obtained from scallop hemolymph by TRIzol method.Gene specially degenerated primer was designed according to the conserved sequence of MGDs.The 5′ end sequences of possible defensin genes could be fished out with improved 5′ RACE and their positive clones were sequenced.The homology of sequences at 5′ end was blasted in GenBank.Results Several unknown cDNA 5′ end sequences were obtained from scallop hemolymph RNA with improved 5′ RACE.The cDNA fragments under 600 bp were AT cloned and three cDNA 5′ end sequences were obtained,with the lengths of 257,275 and 511 bp,respectively.There was no similar genes in homology with these cDNA 5′ end sequences in GenBank.Conclusion Three cDNAs 5′ end sequences from scallop hemolymph could be new genes.It is available to use improved 5′ RACE to screen gene fragments containing defensin conserved sequence.