CLONING AND DEVELOPMENTAL EXPRESSION OF CHORISTONEURA HORMONE-RECEPTOR-75 - A HOMOLOG OF THE DROSOPHILA E75A GENE

Cloning and characterization of a cDNA of the spruce budworm, Choristo neura fumiferana, that showed high amino acid similarity with the dedu ced amino acid sequences of E75 cDNAs cloned From Manduca sexta, Galle ria melonella, and Drosophila melanogaster are described. Initially, a cDNA fragment and then a full length cDNA were cloned from C. fumifer ana. The longest open reading Frame of this cDNA had 690 codons and ii s deduced amino acid sequence had all five domains typical of a steroi d hormone nuclear receptor. The deduced amino acid sequence of this cD NA showed the highest identity with the deduced amino acid sequence of E75A cDNAs cloned From M. sexta, G. melonella, and D. melanogaster, a nd is therefore named Choristoneura hormone receptor 75A (CHR75A). The CHR75A cDNA probe detected a 2.6 kb mRNA that was abundant at the tim e of the ecdysteroid peaks during molting in the embryonic, larval and pupal stages. In the sixth instar larvae, CHR75 mRNA was detected in the epidermis, fat body, and midgut, and maximum expression was observ ed during the prepupal peak of ecdysteroids in the hemolymph. CHR75 mR NA was induced in ecdysone treated CF-203 cells and in the midgut, fat body and epidermis of larvae that were fed the non-steroidal ecdyster oid agonist, RH-5992. In vitro transcription and translation of the CH R75A cDNA yielded a 79 kDa protein that bound to the retinoic acid rec eptor related orphan receptor response element (RORE). (C) 1997 Wiley- Liss, Inc.