Resumen
Parasitization of newly ecdysed third, fourth, or fifth instar Manduca sexta larvae by the gregarious braconid wasp Cotesia congregata induces synthesis of new hemolymph proteins in the host. Analysis of hemolymph from parasitized and unparasitized control larvae using SDS gel electrophoresis showed that a major 33 kd band, plus several minor bands, were synthesized in parasitized but not control larvae; autoradiograms of proteins labeled in vivo for 1 hr with [35S]methionine indicated that synthesis of the 33 kd polypeptide began a few hours following oviposition by the wasp. Synthesis of the 33 kd parasitism-specific polypeptide was induced in unparasitized larvae by the injection of ovarian calyx fluid from adult female wasps; this fluid is known to contain two morphologically distinct types of virus particles that are normally injected into the host along with eggs during parasitization. Exposure of calyx fluid to psoralen in the presence of long-wave u.v. light destroyed its capacity to induce synthesis of the 33 kd protein, suggesting that synthesis of this polypeptide may be mediated by viral nucleic acid.
| Idioma original | English |
|---|---|
| Páginas (desde-hasta) | 439-455 |
| Número de páginas | 17 |
| Publicación | Insect Biochemistry |
| Volumen | 17 |
| N.º | 3 |
| DOI | |
| Estado | Published - 1987 |
Nota bibliográfica
Funding Information:Many insectsi n addition to thosem entionedp re-viously experiencea lterationsi n hemolymphp oly- Several hemolymph polypeptidesa re present in terminal stage hosts but not unparasitizedl arvae of the same age (Beckagea nd Templeton, 1986; Beckage1, 986)I.n fifth instar hosts, twmo inor bands (ca 60 and 100 kd,r espectivelya) re seena s early as day 0 and a third very abundant high molecular weight( > 120k d) polypeptidea ppearsi n the hemo- lymph a few daysl ater;t heyr emaini n theb lood even after the wasps emerge( Beckagea nd Templeton, 1986; Fig. 9). These polypeptidesa re detectedi n hemolympho f all terminal stageh ostsr egardlesso f their age( Beckagea nd Templeton,1 986) assh owni n Fig. 8. Clearly they are synthesizedin accordance with the stageo f developmenot f the parasitesr ather than their host. The early stage 33 kd parasitism-specificp oly- peptidec haracteristico f newly parasitizedl arvae is clearlya bsentw henthe waspse mergefr om their host (Beckagea nd Templeton, 1986;F igs 8 and 9). A developmentapl rofile of hemolymph polypeptides indicatet hat the 33 kspde ciesg raduallyd ecreasedin abundanced uring the first 4 days of parasitism( Fig. 9) suggestingit might be associatedw ith the initial establishmento f infection. Moreover, it was not synthesized(c ertainlyn ot to any greatd egreef)o llow- ing molting of the hostto thef ifth instara s parasitism begant o have a distinct inhibitory effecto n growth (Fig. 3). Currently we are examiningt he time cause of cessationo f synthesiso f the 33 kdp olypeptide Acknowledgements-This work was supportedb y grants relative to developmento f the parasitesa nd their from the National Science Foundation (DCB-8216013), host. US. Departmento f Agriculture (82~CRCR-l-1221)a nd Dahlman and Greene( 1981)d escribedo ne protein National Instituteso f Health (5ROlDK32305-03t)o N. E. uniquely presentin parasitizedla rvaea nd stated that Beckagea, nd from theC anadianM edicalR esearchC ouncil threeb ands foundin hemolymphf rom unparasitized assistanceo f L. Rutledge,S . Jordan, and B. Stirling with (MA5975)t o D. B. Stoltz. We gratefullya cknowledgeth e larvae were undetectabled uring parasitism. Esti-insect rearing,a nd thank E. A. Lamoreuxf or assistance mateso f the molecularw eightso f the proteinsw ere with manuscriptp reparation.W e also thank Dr Kemet not made, making comparisons with our data Spence( WashingtonS tateU niversity)f or technicala dvice, difficult. Some bands observedt o be absent could and Dr S. N. Thompson( Universityo f California, River- represents ubunits of the hemolymph arylphorin side) for commentso n the manuscript.I n addition, we manducin,w hich is quantitativelyr educedd uring the sincerelyt hankD r Lois Miller (Universityo f Georgia)a nd final stageso f parasitism( Beckage,1 985;B eckage Dr Marijo Wilson (Universityo f Kentucky) for providing and Templeton,1 986)T. his effecti s likely due to the us with virus samplesa s cited in the Discussion. lower rate of food consumptiona nd growtho f para- sitizeda s comparedt o unparasitizedla rvae( seeR id- diford and Hice, 1985).A s Dahlman and Greene (1981 ) examinedo nly hostst hat had beenp arasitized severald ays earlier, it is unlikely they detectedt he 33 kd polypeptided escribedh ere. The enzymep henoloxidaseis also affectedd uring