Differential expression of the two duplicated insecticyanin genes, ins-a and ins-b, in the black mutant of Manduca sexta.
The black (bl) mutant larvae of Manduca sexta produces no detectable juvenile hormone (JH) during the molt to the 5th instar. To investigate the JH control of expression of the two insecticyanin genes, ins-a and ins-b, developmental changes of the two mRNAs were examined in this mutant. In the epidermis of the freshly ecdysed larvae, the two mRNAs were hardly detectable. Twelve hours after ecdysis, the two mRNAs appeared in low levels and were then gradually increased with ins-a mRNA rising to a plateau from Day 1 to Day 2 morning and ins-b mRNA in Day 2. During these early developmental stages, the epidermal level of the two mRNAs in the bl mutant was substantially lower than that observed in the wild-type larvae. On Day 3 of the 5th instar when the larval epidermis becomes pupally committed, the two mRNAs in both bl mutant and wild-type larvae show a similar differential expression pattern. In the fat body, the level of both ins-a and ins-b mRNAs was higher than that found in the wild-type larvae. Exogenous JH almost restores the level of the two mRNAs in both epidermis and fat body of the Day 0 5th-instar bl mutant larvae to that observed in wild-type animals of the same stage. These results suggest that JH may enhance expression of the two insecticyanin genes in the epidermis but partially repress their expression in the fat body during early development of the wild-type 5th-instar larvae.
Li
W C
WC
Department of Zoology, Unversity of Washington, Seattle 98195, USA.
D000818:Animals; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D019476:Insect Proteins; D007447:Invertebrate Hormones / Q000096:biosynthesis* / Q000235:genetics; D007814:Larva; D018402:Manduca / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005810:Multigene Family; D009154:Mutation; D012333:RNA, Messenger / Q000096:biosynthesis; D012867:Skin / Q000378:metabolism; D014158:Transcription, Genetic
D019476:Insect Proteins; D007447:Invertebrate Hormones; D012333:RNA, Messenger; C043409:insecticyanin protein, insect