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Molecular cloning of a second prophenoloxidase cDNA from the mosquito Armigeres subalbatus : prophenoloxidase expression in blood‐fed and microfilariae‐inoculated mosquitoes
Author(s) -
Huang L. H.,
Christensen B. M.,
Chen C. C.
Publication year - 2001
Publication title -
insect molecular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.955
H-Index - 93
eISSN - 1365-2583
pISSN - 0962-1075
DOI - 10.1046/j.1365-2583.2001.00241.x
Subject(s) - prophenoloxidase , biology , complementary dna , midgut , open reading frame , microbiology and biotechnology , rapid amplification of cdna ends , blood meal , western blot , northern blot , gene , molecular cloning , innate immune system , biochemistry , peptide sequence , botany , receptor , larva , food science
Melanization constitutes an important component in various aspects of insect life, including cuticular sclerotization, egg‐shell tanning, melanization of parasites and wound healing. Recently, a cDNA encoding prophenoloxidase (pro‐PO), a key enzyme in the biosynthesis of melanotic material in insects, was cloned from microfilariae (mf)‐inoculated mosquitoes, Armigeres subalbatus. However, results of Northern blot analyses indicated that two pro‐POs might be present in Ar. subalbatus and these pro‐POs might be responsible for two distinct physiological functions, egg‐shell tanning and melanization of parasites. Subsequently, the second pro‐PO cDNA (As‐pro‐PO II) was cloned from blood‐fed Ar. subalbatus by rapid amplification of cDNA ends polymerase chain reaction. The 2210 bp As‐pro‐PO II cDNA contains a 41 bp 5′‐non‐coding region, a 2064 bp open reading frame and a 105 bp 3′‐non‐coding region. A hydrophobic signal peptide for endoplasmic reticulum targeting is not found in the N‐terminal region. The deduced amino acid sequence of As‐pro‐PO II shares a high degree of identity (81.5%) with that of the As‐pro‐PO I obtained from mf‐inoculated Ar. subalbatus . Both Northern blot and reverse transcription polymerase chain reaction analysis demonstrated that these two mosquito pro‐POs are persistently expressed in mosquito haemocytes and not in fat body, midgut, or ovaries. The expression of As‐pro‐PO I and As‐pro‐PO II in mosquitoes is associated with melanization of mf and blood feeding, respectively.