In silico Analysis and Expression Patterns of TmLysozyme-like Gene in Tenebrio molitor

Lysozyme, the antibacterial protein, is well known to hydrolyse the bacterial cell wall component (peptidoglycan) in insects. In this study, we identified one lysozyme-like (TmLyso-like) gene from Tenebrio molitor EST database, and investigated gene structure and temporal/spatial expression patterns of TmLyso-like transcripts in T. molitor. TmLyso-like gene contains 417 bp of ORF sequence encoding 138 amino acid residues. Domain analysis showed a signal peptide region, and a C-type lysozyme/α-lactalbumin family domain. It also contains conserved eight cysteine residues which are involved in construction of 3D structure. Developmental expression analysis indicates that TmLyso-like mRNA is highly expressed in the young larvae (10th-12th instar larvae), 1 and 3-days old pupae and adults. Interestingly, TmLyso-like mRNA was mainly expressed in fat body and Malpighian tubules in late instar larvae, and integument, hemocytes and Malpighian tubules in 5-days old adults. Induction pattern analysis of TmLyso-like mRNA against microbial challenges showed that TmLyso-like mRNA was strongly induced by Escherichia coli at 3 and 12 h-post injection in fat body. In addition, the highest level of TmLyso-like mRNA was detected in early time point after injection of three different pathogens (E. coli, Staphylococcus aureus, and Candida albicans) in the hemocytes. However, it was not strongly induced by injection of these pathogens in the gut. In conclusion, TmLyso-like gene might play a role in innate immunity in T. molitor although precise function remains to be elucidated using recombinant TmLyso-like protein.