Identification and Expression Profile Analysis of Antimicrobial Peptide/Protein in Asian Corn Borer, Ostrinia furnacalis (Guenée)

Abstract

Antimicrobial peptides/proteins (AMPs) are a group of immune proteins that exhibit strong antibiotic properties against numerous infectious bacterial strains. They are evolutionarily conserved and present in every kingdom and phylum, ranging from prokaryotes to humans. We analyzed the transciptome from the larvae of Asian corn borer, Ostrinia furnacalis (Guenée), and identified several putative AMP transcripts, OfgLys5, OfgLys6, OfgLys10, OfgAtt, and OfgIID. OfgLys5, OfgLys6, and OfgLys10 are all highly homologous with c-type lysozymes, and OfgAtt shows significant identities with Lepidoptera attacin. The amino acid sequence of OfgLys5 and OfgLys6 possessed all conserved features critical for fundamental structure and function of c-type lysozyme, including the two catalytic sites, Glu32 and Asp50. OfgAtt is a typical glycine-rich protein. The antimicrobial activity of O. furnacalis hemolymph increased significantly after injection with Escherichia coli, Micrococcus luteus, or Beauveria bassiana. OfgAtt, IDD, and Lys6 are expressed at low level prior to the challenge, but strongly induced against Gram-positive and negative bacteria, and fungi. Under the same inducement conditions, the transcripts of these three genes elevated most when fifth instar larvae were injected. Therefore, O. furnacalis larvae are induced to produce antimicrobial materials in the hemolymph after the infection, and increase of lysozyme and attacin may contribute to the antimicrobial activity.

Cloning, Expression, and Characterization of Prophenoloxidases from Asian Corn Borer,Ostrinia furnacalis(Gunée)

“…O. furnacalis larvae were reared on an artificial diet at 28°C under a relative humidity of 70–90% and a photoperiod of 16 h light and 8 h darkness [38]. …”

“…To check the expression of O. furnacalis PPOs after different microbial injections, day one fifth-instar larvae from the same batch were injected into the hemocele with 3  μ L of sterile water containing formalin-killed Escherichia coli DH5 α (2 × 10 5 cells/ μ L), dried M. luteus (3  μ g/ μ L), Beauveria bassiana suspension (2 × 10 5 conidia/ μ L, B. bassiana conidia suspension was prepared as described previously [38]), or sterile water as a control. After 20 h (10 h for B. bassiana treatment), five larvae were collected from the challenged group and 5 from the control group, and total RNA samples were prepared from each larva.…”

cDNA CLONING AND TRANSCRIPTIONAL REGULATION OF THE CECROPIN AND ATTACIN FROM THE ORIENTAL FRUIT FLY, Bactrocera dorsalis (DIPTERA: TEPHRITIDAE)

“…After the excision of the signal peptide, the propeptide is further processed to produce a mature peptide by cleaving at the site, RXXR, which is a potential furin processing site (Molloy et al., ). The RXXR site is usually R(A/V)RR in most insect attacins (Zhang et al., ), but it is present as RVAR in two attcin C, BdAttC and CcAttC, from the Tephritidae (Fig. ).…”

Serine protease SP105 activates prophenoloxidase in Asian corn borer melanization, and is regulated by serpin-3

“…To check the expression profiles of SP105 under different inducement conditions, day 1 fifth instar larvae from the same batch were injected into the hemocoel with 3 μl of sterile water containing formaline-killed E. coli DH5α (2 × 10 5  cells/μl), dried M. luteus (3 μg/μl), B. bassiana suspension (2 × 10 5  conidia/μl, B. bassiana conidia suspension was prepared as described previously55), or sterile water as a control. After 20 h (10 h for B. bassiana treatment), each five larvae from challenged and control group were collected, and total RNA samples were individually prepared.…”