Two vitellogenin genes from Blaberus discoidalis : molecular cloning, sequence analyses, expression profiles, and induction by juvenile hormone /
Two cDNAs coding for vitellogenins (Vgs, precursors of the major yolk proteins) of cockroach, Blaberus discoidalis, were cloned and sequenced. Analysis of the deduced amino acid sequences of these Vgs (BdVg1 and BdVg2) revealed that each contains three polymerize regions. Two are N-terminally locate...
| Main Author: | |
|---|---|
| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1999.
|
| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=733675431&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Two cDNAs coding for vitellogenins (Vgs, precursors of the major yolk proteins) of cockroach, Blaberus discoidalis, were cloned and sequenced. Analysis of the deduced amino acid sequences of these Vgs (BdVg1 and BdVg2) revealed that each contains three polymerize regions. Two are N-terminally located where they flank a potential consensus cleavage sequence recognized by convertase, an endoprotease. The third region is near the C-terminal end. Bdvg1 and Bdvg2 are 30.0% identical in amino acid sequence with three highly homologous regions. Two of these regions are in the N-terminal halt-and align with regions highly conserved among the Vgs of mosquito, silkworm and boll weevil. The third lies within the last 45 amino acid residues of the C-terminal end and appears to be species-specific. Twelve volitionally conserved cysteine residues are located within 650 amino acid residues of the C-terminal ends of the Vgs, suggesting selective pressure exists for maintenance of disulfide bond formation ill the C-terminal ends. Northern hybridization analyses demonstrated that Bdvg1 and BdVg2 mRNAs are expressed in sex- and stage-specific manners, and are juvenile-hormone (JH) dependent. The nRNAs of the Vgs were undetectable in pregnant females, but were induced upon exposure to JH. Adult males were also induced to express Vg transcripts by juvenile hormone-analog (JHA) treatment. Protein synthesis is required prior to induction, indicating an indirect action of JH in activating Vg gene transcription. The level of accumulated Vg transcripts in day-0 (day of adult molt) JHA-treated adult males was comparable to that in normal adult females of similar age administered JHA.However, the responsiveness of adult male fat body to JHA-induced Vg expression decreases with age, yet that of decapitated, allatectomized plus cardiacectomized, or allatectomized adult males gained responsiveness Administration of extracts of corpora allata/corpora cardiaca (CC/CA) or of synthetic B. discoidalis hypertrehalosemic hormone (HTH) to Jl'tArilzduced adult males suppressed the Bdvg1 transcript approximately 80%, suggesting that HTH, and perhaps other factors from the CC/CA, is involved ill the decreased sensitivity of male fat body to JH-induced Vg expression during the first week of adult life. |
|---|---|
| Item Description: | Vita. "Major Subject: Entomology". |
| Physical Description: | ix, 99 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 83-93). |