CLONING, CHARACTERIZATION, AND GENETICS OF THE JUVENILE-HORMONE ESTERASE GENE FROM HELIOTHIS-VIRESCENS

The gene for juvenile hormone esterase (JHE) was cloned from Heliothis virescens (Lepidoptera: Noctuidae). A genomic library was constructed from embryonic DNA and screened with a homologous N-terminal probe fr om the JHE cDNA. Five genomic clones were isolated and analyzed by dot blot hybridization using regions of the JHE cDNA as probes. Clone C h ybridized to both 5' and 3' probes from the JHE cDNA, suggesting that clone C contains both ends of JHE gene. This was verified by sequencin g the ends of the JHE gene from clone C using primers from both the 5' and 3' ends of the JHE cDNA. Additional sequencing and restriction ma pping were used to characterize the gene. The gene is c. 8 kb long and contains four introns with consensus intron-exon junctions. One of th e introns is relatively large (4 kb) and is situated near the extreme 5' end of the gene. Genetic analysis of RFLP variation in interspecifi c and intraspecific crosses shows that the JHE locus is single-copy wi th no closely related paralogs and is autosomally encoded in Heliothis . Therefore the developmental pattern of expression of this gene and t he previously documented sequence variation in cDNA clones is not expl ainable by reference to a JHE gene family with distinct structural loc i for the different forms.