Developmental profiles and ecdysone regulation of the mRNAs for two ecdysone receptor isoforms in the Mediterranean fruit fly Ceratitis capitata.
Using 5' RACE with specific primers for the ecdysone receptor B1 isoform of the Mediterranean fruit fly (medfly), Ceratitis capitata, we isolated a cDNA clone encoding the specific region of the medfly ecdysone receptor A isoform (CcEcR-A). The CcEcR-A-specific region was very similar to the EcR-A-specific region of Drosophila melanogaster and less similar to the EcR-A-specific regions of Lepidoptera. The developmental expression of both CcEcR-A and CcEcR-B1 mRNAs was studied in whole animals, salivary glands and ovaries by RT-PCR, using isoform-specific primers. Both CcEcR mRNAs are present in very early embryos, decrease to very low levels during the first hours of embryogenesis and are highly expressed in all consequent embryonic stages. During metamorphosis both isoforms are present showing two peaks; the first at the larval-prepupal transition and the second during the second half of prepupal development. These peaks are correlated with the two puffing cycles and the two major 20-hydroxyecdysone (20E) increases that occur during medfly metamorphosis. CcEcR-B1 mRNA was directly induced in larval salivary glands in vitro by 20E, even at very low concentrations of the hormone, while CcEcR-A mRNA was slightly induced only by high 20E concentrations and in the absence of a protein synthesis inhibitor. During oogenesis, the CcEcR mRNAs were expressed synchronously, peaking at the beginning of both previtellogenic and vitellogenic phases.
Verras
M
M
Department of Biology, University of Patras, Greece.
Gourzi
P
P
Zacharopoulou
A
A
Mintzas
A C
AC
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D033622:Ceratitis capitata / Q000145:classification / Q000235:genetics* / Q000254:growth & development*; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D010802:Phylogeny; D020033:Protein Isoforms / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics*; D011987:Receptors, Steroid / Q000235:genetics*; D012469:Salivary Glands / Q000502:physiology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D020033:Protein Isoforms; D012333:RNA, Messenger; D011987:Receptors, Steroid; C055469:ecdysone receptor