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Parasitization by Macrocentrus cingulum (Hymenoptera: Braconidae) influences expression of prophenoloxidase in Asian corn borer Ostrinia furnacalis
Author(s) -
Feng Congjing,
Huang Jianhua,
Song Qisheng,
Stanley David,
Lü Wenjing,
Zhang Yong,
Huang Yongping
Publication year - 2011
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.20425
Subject(s) - biology , ostrinia furnacalis , prophenoloxidase , complementary dna , midgut , signal peptide , open reading frame , microbiology and biotechnology , hemolymph , manduca sexta , peptide sequence , biochemistry , gene , botany , insect , lepidoptera genitalia , innate immune system , larva , receptor
Abstract A prophenoloxidase (PPO) cDNA (OfPPO) was cloned from the Asian corn borer Ostrinia furnacalis . Sequence analysis revealed a full length transcript of the OfPPO cDNA with 2,686 bp, containing a 2,079 bp open reading frame (ORF), a 73‐bp 5′‐untranslated region, and a 534‐bp 3′‐untranslated region with a poly(A) signal. The ORF encodes a 693‐amino acid polypeptide, containing two distinct copper‐binding regions, a plausible thiol ester site, two proteolytic activation sites, and a conserved C‐terminal region, but lacks a signal peptide sequence. Expression of the OfPPO transcript in the plasma, hemocytes, fat body and midgut was inhibited by Macrocentrus cingulum at 4 h post‐parasitization (pp). In situ hybridization analysis showed that the hemocytes, especially the oenocytoids, hybridized strongly with the DNA probes of the OfPPO gene. No signal was detected in the cuticular epithelium or fat body of the parasitized larvae. Colloidal gold particles were used to visualize the PPO by immunoelectron microscopy. The time course study revealed a decrease in the labeling of the OfPPO at 4, 6, 8, 12, and 1 day pp in the larval integument and midgut parasitized by M. cingulum . We infer from time course studies of OfPPO gene expression and PO enzymatic activity that OfPPO in the integument is released from hemocytes and that the OfPPO expression was influenced at the transcriptional, translational, and then the post‐translational level by parasitization challenge. © 2011 Wiley Periodicals, Inc.