U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 close



Research
                Research Home
                            National Programs
                            Research Projects
                            Scientific Manuscripts
                            International Engagement
                            Scientific Software/Models
                            Databases and Datasets
                            Office of Scientific Quality Review
            Media
                News & Features
                            Multimedia
                            Briefing Room
                            Down on the Farm
                            Press Room
                            Science in Your Shopping Cart
                            Scientific Discoveries
                            Tellus
                            Under the Microscope
            About ARS
                About ARS Home
                            Staff Directory
                            Labs and Research Centers (Map)
                            Headquarter Offices
                            Organizational Chart
                            Employee Services (REE Employees Only)
                            Office of Outreach, Diversity, and Equal Opportunity
            Work With Us
                Work With Us Home
                            ARS Vacancies at USAJOBS
                            Careers at ARS Information
                            Scientific Collaborations
                            Extramural Agreements
                            1890 Faculty Research Sabbatical ProgramSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            LEWIS, DANIELLE - TAMU, DEPT OF ENTOMOLOGYitem
                                            Spurgeon, Daleitem
                                            Sappington, Thomasitem
                                            KEELEY, LARRY - TAMU, DEPT OF ENTOMOLOGY
  Submitted to: Journal of Insect Physiology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 7/12/2002
                                    Publication  Date: 12/15/2002
                                    Citation: Lewis, D.K., Spurgeon, D.W., Sappington, T.W., Keeley, L.L. 2002. A hexamerin protein, AgSP-1, is associated with diapause in the boll weevil. Journal of Insect Physiology. 48:887-901.Interpretive Summary: The boll weevil is a major pest of cotton that survives the winter in a state of dormancy called diapause.  Although efforts to control the weevil would be enhanced by a better understanding of diapause, this important aspect of the weevil's ecology remains poorly understood.  In particular, little is known of the biochemical changes that occur during diapause.  Our objective was to identify chemicals in the blood of the boll weevil that reliably indicate whether a given weevil is in diapause.  Examination of the blood of diapausing weevils revealed the presence of a specialized storage protein absent from the blood of reproductive (not diapausing) weevils.  An antibody (a chemical that reacts specifically with the protein) reacted with the blood of diapausing weevils but not with the blood of reproductive weevils.  Also, when the storage protein was present another protein typical of egg production was absent.  However, treatment with a juvenile hormone (a chemical that in most insects controls egg production) did not cause diapausing weevils to produce eggs.  In further testing the gene responsible for production of the storage protein was identified and described, and was found to be active in fat tissues of both male and female diapausing weevils.  Our results suggest the storage protein is a reliable indicator of diapause, and that diapause is not ended by the hormone that controls egg production.  These findings provide a method of identifying diapausing boll weevils without killing them, and presents a new tool for use in future studies of diapause.
                                Technical Abstract: Diapause is an aspect of boll weevil, Anthonomus grandis Boheman, ecology that is critically important to successful management of this serious pest of cotton (Gossypium hirsutum L.).  Yet this phenomenon remains poorly understood.  In particular, reliable biochemical indicators of the dormancy that would facilitate a better understanding and further study of diapause are lacking.  Our objective was to identify and characterize such an indicator by examining the hemolymph composition of diapausing and reproductive weevils.  Hemolymph subjected to SDS-PAGE revealed the presence of a 77-kDa hexamerin (AgSP-1) strongly associated with the diapause morphology.  An antibody developed from the N-terminal sequence of the first 25 amino acids reacted only with hemolymph from dormant weevils.  Also, presence of the yolk protein, vitellogenin (VG), was inversely correlated with AgSP-1, however treatment with a juvenile hormone analog (methoprene) did not activate reproductive development in dormant weevils.  Using a genomic DNA library and 3' RACE, two clones were isolated that yielded the complete sequence of AgSP-1 as well as a portion of the 5' untranslated region.  Northern blot analysis confirmed the presence of a 2.5-kB transcript for AgSP-1 in the fat body of dormant weevils that was also present to a lesser extent in the fat body of reproductive weevils.  Dormant weevils of both sexes showed similar levels of AgSP-1 expression.  Presence of the VG transcript was inversely correlated with that of AgSP-1 mRNA.  Our data suggests that AgSP-1 is a diapause-specific protein in adult weevils and that juvenile hormone alone is not effective in terminating dormancy.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov