title: Isolation and developmental expression of two nuclear receptors, MHR4 and betaFTZ-F1, in the tobacco hornworm, Manduca sexta.
abstract: The cDNAs for two members of the nuclear receptor superfamily were isolated from the tobacco hornworm, Manduca sexta. The deduced amino acid sequence of MHR4 shows 93-95% identity in the DNA-binding domain and the first portion of the hinge (D) region with the germ cell nuclear factor (GCNF)-related factors (GRFs) of the silkworm, Bombyx mori, and the mealworm, Tenebrio molitor, and with a genomic sequence from the fruit fly, Drosophila melanogaster. Northern blot hybridization showed that a 7.5 kb MHR4 mRNA appeared in Manduca abdominal epidermis just as the ecdysteroid titer began to decline during the larval molt, disappeared about 12 h later, then transiently reappeared shortly before larval ecdysis. During the pupal and adult molts, a similar pattern of expression was seen (the very end of the adult molt was not studied). At peak times of expression in the epidermis, MHR4 mRNA was also present in fat body and the central nervous system (CNS). The deduced amino acid sequence of Manduca FTZ-F1 is 100% and 96% identical to that of B. mori and Drosophila betaFTZ-F1, respectively, in the DNA-binding domain and the adjacent hinge region including the FTZ-F1 box. Northern blot analysis showed that the >9.5 kb betaFTZ-F1 mRNA appeared in Manduca epidermis during the decline of the ecdysteroid titer in the larval, pupal and adult molts as the first peak of MHR4 mRNA declined, then it disappeared in the larval and pupal molts before the second peak of MHR4 appeared. betaFTZ-F1 mRNA was also found in fat body and the CNS at the time of peak expression in the epidermis during the larval and pupal molts. Both MHR4 and betaFTZ-F1 mRNAs were found in the testis during the onset of spermatogenesis in the prepupal period.
authors.affiliation: Department of Zoology, University of Washington, Box 351800, Seattle, WA 98195-1800, USA.
authors.forename: J
authors.initials: J
authors.lastname: Weller
authors.forename: G C
authors.initials: GC
authors.lastname: Sun
authors.forename: B
authors.initials: B
authors.lastname: Zhou
authors.forename: Q
authors.initials: Q
authors.lastname: Lan
authors.forename: K
authors.initials: K
authors.lastname: Hiruma
authors.forename: L M
authors.initials: LM
authors.lastname: Riddiford
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004268:DNA-Binding Proteins / Q000235:genetics*; D004817:Epidermis / Q000378:metabolism; D051717:Fushi Tarazu Transcription Factors; D015870:Gene Expression; D018398:Homeodomain Proteins; D019476:Insect Proteins / Q000235:genetics*; D008297:Male; D018402:Manduca / Q000235:genetics*; D008969:Molecular Sequence Data; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics*; D054339:Steroidogenic Factor 1; D013737:Testis / Q000378:metabolism; D014018:Tissue Distribution; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D019476:Insect Proteins; C432952:MHR4 protein, Manduca sexta; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; C499713:nuclear hormone receptor FTZ-F1, Bombyx mori