ISSN:0739-4462    

DOI:10.1002/arch.940030702

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940030703

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractIn the analysis of insect juvenile hormone (JH) function, metamorphosis is complicated by ecdysone and JH acting concurrently. Although JH stimulation of vitellogenin synthesis by the fat body is by no means simple, it is possible to focus on the events leading to selective transcription of a single gene. The two‐striped grasshopperMelanoplus bivittatuswas used to study nuclear binding of JH during vitellogenesis and to investigate proteins binding JH that have been found in hemolymph and fat body. M.bivittatusreproduction is regulated by JH. The fat body nuclei increased in ploidy with time after eclosion, and, because the antiallatotropin precocene completely inhibited vitellogenin production, we assume that this grasshopper differs little fromLocusta migratoriain which JH stimulates transcription of the vitellogenin gene. Proteins that bind JH with high affinity were identified with the hydroxyapatite assay. Characterization of the JH‐binding proteins included ion exchange chromatography, gel filtration, and polyacrylamide gel electrophoresis. Four proteins of hemolymph and three proteins of fat body bound JH with high affinity, and binding was competitively inhibited by JHIII. Short‐term tissue culture was used to follow [3H]JH‐III uptake by fat body and to determine the intracellular distribution of the hormone. Proteins that bound JH were extracted from nuclei with KCI, and they increased in number from the time of adult emergence to the time of maximum vitellogenin secretion. The JH‐binding proteins from nuclei might be receptors that help regulate the selective expression of genes for vitellogenin and for other proteins indu

ISSN:0739-4462    

DOI:10.1002/arch.940030704

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractAn ecdysteroid‐binding protein has been demonstrated in nuclear and cytosolic extracts of cultured Drosophila cells (Kccells). Attempts to purify the binding moiety have been hampered because of the small number of binding sites (ca 1,000/cell) and sensitivity of the ecdysteroid binding moiety toward salt (dissociation at 150 mM). Recently 3α[3H]kaladasterone and 3α[3H]muristerone A have been synthesized. The binding kinetics of these two ecdysteroids are similar to ponasterone A. Photoaffinity labeling of the ecdysteroid receptor in Kc cells was attempted using the 3α[3H]kaladasterone, and standard protein chromatographic techniques have been used to examine the 3α[3H]muristerone A‐receptor complex, which is less sensitive to salt dissociation. Attempts to characterize the protein to which these ligands have been attached will be di

ISSN:0739-4462    

DOI:10.1002/arch.940030705

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractInLocusta migratoria, vitellogenin (Vg) is normally produced only in adult female fat body under stimulation by juvenile hormone (JH). This permits study of (a) programming of genes for expression and (b) modulation of expression by JH. FromL. migratoriagenomic libraries, two Vg genes (A and B) have been cloned. Coding regions encompass 10‐12 kbases of DNA, contain introns, and hybridize with 6,300 nucleotide mRNAs. Although the 5'‐exons, coding for signal peptides, are similar in sequence, the remaining coding sequences have distinct restriction maps and show no crosshybridization. Upstream DNA from the two genes has some sequence similarity, corresponding to potential regulatory regions. Dot hybridization assays of mRNAs A and B in locust fat body after induction by methoprene show coordinate expression of the two Vg genes and also a third, unidentified JH‐regulated gene. In the hope of providing a system for identification of control sequences, P element‐mediated transformation has been used to transfer locust DNA intoDrosophila.From Vg gene B, a central block was deleted, to give a mini‐Vg gene comprising 5' and 3' terminal coding sequences plus upstream flanking DNA. This was incorporated into the P element vector Carnegie 20 and injected intoDrosophilaembryos. Three transformed fly lines were obtained in which the locust mini‐Vg gene was integrated at different chromosomal sites. On Northern blots of fly RNA, however, no expression of the locust sequences could be detected, even though the accompanying rosy gene was expressed. This suggests that the locust regulatory sequences were not recognized inDrosophila, and current effort is directed toward developing a homologous locust transformation system for expression assay of cloned JH‐re

ISSN:0739-4462    

DOI:10.1002/arch.940030706

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractStudents of insect metamorphosis have in the past accepted the paradigm that the structures of different metamorphic stages are built from molecules coded for by different sets of genes. A substantial body of evidence, based on cuticular proteins, has now accumulated that casts doubt on that paradigm. This paper summarizes the evidence and provides a new framework for viewing the activities of genes during metamorphosis.Studies on promoter utilization for alcohol dehydrogenase inDrosophila melanogasterreveal that cells change promoters at the onset of metamorphosis. These data suggest that modifications of regulatory elements rather than duplications of structural genes may have occurred to permit the evolution of metamorphosis.

ISSN:0739-4462    

DOI:10.1002/arch.940030707

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractControl of specific protein synthesis by juvenile hormone during sexual maturation and reproduction is being studied in the left colleterial gland of the cockroachPeriplaneta americana.Rates of specific oothecin synthesis and oothecin mRNA concentrations have been measured during sexual maturation and the effects of allatectomy and administration of juvenile hormone determined. The heterogeneity of the oothecins has been characterized and found to be due probably to a multiplicity of structural genes. The complete primary structure of the major oothecin has been deduced from the sequences of cloned cDNAS. It can be divided into a central region and two flanking arms that share sequence features. The structures of the oothecins show strong homologies with the silkmoth chorion proteins.

ISSN:0739-4462    

DOI:10.1002/arch.940030708

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractAs the tobacco hornworm (Manduca sexta) larva feeds and grows, the abdominal epidermis synthesizes larval endocuticular proteins. During a molt this synthesis temporarily ceases while the cells deposit a new epicuticle; then these proteins reappear in a sequential manner, some before ecdysis, others after ecdysis. At the time of metamorphosis, the epidermis becomes pupally committed and ceases synthesizing these endocuticular proteins. Northern and dot blot hybridization analysis using cDNA clones for three different low‐molecular‐weight larval cuticular proteins showed that RNA transcription of all three ceased by the time of head cap slippage during the molt, then begins again just before ecdysis, one showing a different time course from the other two. All responded to the commitment peak of ecdysteroid in the absence of juvenile hormone (JH) by a permanent cessation of transcription.During the final day of feeding (day 3) of the 5th instar the cuticular lamellae become 5–10 times thinner coincidentally with a change in cuticular protein synthesis involving a cessation of synthesis of many of the endocuticular proteins and the appearance of at least three new proteins — 14.5, 15, and 27 kd (kilodaltons). Incubation of day 15th instar epidermis with 10–100 ng/ml 20‐hydroxyecdysone (20HE) induced the synthesis of the 27‐kd protein and the transcription of the mRNAs for the 14.5‐ and 15‐kd proteins. Incubation in the absence of hormones or with 20HE in the presence of JH prevented the appearance of these new proteins and the deposition of thin lamellae. The mRNAs for three endocuticular proteins whose synthesis ceases on day 3 showed differing responses to 20HE and JH. Thus, the sequential program of larval endocuticular gene expression is controlled primarily by hormonal titers in both the molt and the

ISSN:0739-4462    

DOI:10.1002/arch.940030709

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractInSarcophaga bullatathere are at least three genes coding for the major yolk polypeptides. By means of the reticulocyte cell‐free translation system in combination with dog pancreatic microsomal membranes, it was demonstrated that minor processing of the peptides occurs inSarcophaga.Prior to secretion, only the cleavage of the signal peptide is observed.In vitro translation experiments also revealed thatSarcophagamales require only 20‐hydroxyecdysone and not juvenile hormone for the induction of the yolk polypeptide transcription. Following a single injection of 20‐hydroxyecdysone in males, in vivo pulse labeling experiments showed that translation of the yolk polypeptides continues for no longer than 24–36 h; only a continuous stimulation by 20‐hydroxyecdysone results in prolonged synthesis of the yolk pol

ISSN:0739-4462    

DOI:10.1002/arch.940030710

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractTranscripts of the dopa decarboxylase (Ddc) gene accumulate within 4 h of the administration of 20‐OH‐ecdysone to mature larvae ofDrosophila.The increase can be explained as the sum of a direct steroid effect, independent of protein synthesis, and an indirect effect, dependent on proteins synthesized after an increase in the hormone titer. By contrast, the peaks of DDC activity in embryos, and perhaps in the first two larval instars and in imaginal discs as well, cannot be ascribed to any direct steroid effects. In fact, a decreasing hormone titer might be required before the Ddc gene can be expressed at these stages. The stage‐specific differences in the molecular mechanisms regulating Ddc gene activity may be reflected in the phenotype of an activity variant,Ddc+4. Molecular studies now underway on the variant Ddc gene might help us to understand the complex multifunctional region that we believe lies upstream of the gene and regulates its expression during develo

ISSN:0739-4462    

DOI:10.1002/arch.940030711

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY