title: Unique synteny and alternate splicing of the chitin synthases in closely related heliothine moths.
abstract: Chitin is an extracellular biopolymer that contributes to the cuticular structural matrix in arthropods. As a consequence of its rigid structure, the chitinous cuticle must be shed and replaced to accommodate growth. Two chitin synthase genes that encode for chitin synthase A (ChSA), which produces cuticular exoskeleton, and chitin synthase B (ChSB), which produces peritrophic membrane, were characterized in the genomes of two heliothine moths: the corn earworm/cotton bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) and the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). In both moths, the two genes were arranged in tandem with the same orientation on the same strand with ChSB located 5' of ChSA. Sequence comparisons showed that the coding sequences were highly conserved with homologues from other species but that the tandem juxtaposed genomic arrangement of the two genes was unique in these insects. The mechanism that has led to this arrangement is unclear but is most likely a recent recombinational event. Transcript mapping of HzChSB and HzChSA in H. zea demonstrated that both transcripts were differentially spliced in various tissues and larval stages. The identification of the HzChSB-E12b alternate spliced transcript is the first report of alternate splicing for the ChSB group. The importance of this splice form is not clear because the protein produced would lack any enzymatic activity but retain the membrane insertion motifs. As for other insects, these genes provide an important target for potential control through RNAi but also provide a subject for broad scale genomic recombinational events.
authors.affiliation: USDA ARS CMAVE, 1700 SW 23rd Drive, Gainesville, FL 32608 USA. Electronic address: Paul.Shirk@ars.usda.gov.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Shirk
authors.affiliation: USDA ARS SIMRU, 141 Experiment Station Road Stoneville, MI 38776 USA. Electronic address: op.perera@ars.usda.gov.
authors.forename: Omaththage P
authors.initials: OP
authors.lastname: Perera
authors.affiliation: USDA ARS BCIRL, 1503 S. Providence, Columbia, MO 65203 USA. Electronic address: kent.shelby@ars.usda.gov.
authors.forename: Kent S
authors.initials: KS
authors.lastname: Shelby
authors.affiliation: USDA ARS CMAVE, 1700 SW 23rd Drive, Gainesville, FL 32608 USA. Electronic address: richard.furlong@ars.usda.gov.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Furlong
authors.affiliation: USDA ARS CMAVE, 1700 SW 23rd Drive, Gainesville, FL 32608 USA. Electronic address: eric.lovullo@ars.usda.gov.
authors.forename: Eric D
authors.initials: ED
authors.lastname: LoVullo
authors.affiliation: USDA ARS BCIRL, 1503 S. Providence, Columbia, MO 65203 USA. Electronic address: hpopham@agbitech.com.
authors.forename: Holly J R
authors.initials: HJ
authors.lastname: Popham
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002687:Chitin Synthase / Q000235:genetics*; D017344:Genes, Insect / Q000235:genetics; D049750:Genome, Insect / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics*; D007814:Larva / Q000235:genetics; D008969:Molecular Sequence Data; D009036:Moths / Q000235:genetics*; D026801:Synteny / Q000235:genetics*
chemical_list: D019476:Insect Proteins; D002687:Chitin Synthase
keywords: Corn earworm; Cotton bollworm; Cuticle; Genetic linkage; Peritrophic membrane; Tobacco budworm