by reverse transcriptase-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends(RACE) methods. The full-length cDNA of was 912 bp with a 480 bp open reading frame(ORF) encoding 159 amino acids, which included a signal peptide of 20 amino acids at the N-terminus and a mature peptide of 139 amino acids. The deduced amino acid sequence had a putative size of 17.69 kD and the theoretical isoelectric point was 7.75. The multiple alignments revealed identity of 91.4% between in the i-type LYZ amino acid sequence. The i-type lysozyme conserved sequence DVGSLSCGP(Y)Y(F)QIK was detected in the amino acid sequence. These results indicate that the cDNA sequence cloned from is a member of the i-type lysozyme family. Real-time quantitative PCR was carried out to measure mRNA expression patterns in the mRNA expression levels in peristome membrane were significantly higher than those of , male gonad, and female gonad (after the LPSand reached its maximum level at 8 h post-stimulation, and decreased gradually thereafter. Thirty-six hours after the LPS challenge, LYZ levels in the