Upregulation of the immune protein gene hemolin in the epidermis during the wandering larval stage of the Indian meal moth, Plodia interpunctella.
Expression of hemolin, which generates an immune protein, was up-regulated in wandering fifth instar larval stage of Plodia interpunctella. The mRNA level peaked in the middle of the wandering stage. Major expression was in the epidermis, rather than in the fat body or gut. To test a possible ecdysteroid effect on hemolin induction we treated with RH-5992, an ecdysteroid agonist, and KK-42, which inhibits ecdysteroid biosynthesis in both feeding and wandering fifth instar larvae. When feeding larvae were treated with RH-5992 the hemolin mRNA level was increased. When wandering larvae were treated with KK-42 its level was reduced. In addition, when KK-42-treated larvae were subsequently treated with RH-5992 the hemolin mRNA level was recovered. These results strongly suggest that ecdysteroid up-regulates the expression of hemolin mRNA. Hormonal and bacterial effects on hemolin induction were further analyzed at the tissue level. Major induction of hemolin mRNA was detected following both RH-5992 treatment and bacterial injection in the epidermis of both feeding and wandering larvae. Minor induction of hemolin was detected in the fat body following a bacterial injection, but not RH-5992 treatment. We infer that in P. interpunctella larvae, the epidermis is the major tissue for hemolin induction in naïve insects and in insects manipulated with bacterial and hormonal treatments.
Aye
Tin Tin
TT
School of Applied Biosciences, College of Agriculture and Life Sciences, Kyungpook National University, 1370 Sankyukdong, Daegu 702-701, Republic of Korea.
Shim
Jae-Kyoung
JK
Rhee
In-Koo
IK
Lee
Kyeong-Yeoll
KY
D000818:Animals; D026461:Ecdysteroids / Q000378:metabolism; D004817:Epidermis / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D007136:Immunoglobulins / Q000235:genetics* / Q000276:immunology; D019476:Insect Proteins / Q000235:genetics* / Q000276:immunology; D007814:Larva / Q000235:genetics* / Q000276:immunology; D009036:Moths / Q000235:genetics* / Q000254:growth & development* / Q000276:immunology; D015854:Up-Regulation
D026461:Ecdysteroids; D007136:Immunoglobulins; D019476:Insect Proteins; C066846:hemolin