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  • 1
    Electronic Resource
    Electronic Resource
    Hormonally-regulated differential expression of the two duplicated insecticyanin genes, ins-a and ins-b, during development of the tobacco hornworm, Manduca sexta (1995)
    Springer
    Development genes and evolution 205 (1995), S. 81-88 
    Details
    ISSN: 1432-041X
    Keywords: Insecticyanin genes ; mRNA ; Hormonal regulation ; Juvenile hormone and 20-hydroxyecdysone ; Manduca sexta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of juvenile hormone (JH) and 20-hydroxyecdysone (20E) on the developmental expression of the two insecticyanin genes, ins-a and ins-b, were investigated with two gene-specific probes. Removal of the corpora allata (-CA, source of JH) clearly delayed and down-regulated the epidermal expression of these genes but enhanced their expression in the fat body during the early development of the fifth instar. Application of JH I to the -CA larvae at the time of head capsule slippage completely restored the normal epidermal expression pattern of the two genes in the early fifth instar, then INS-a mRNA declined prematurely whereas INS-b mRNA remained similar to that in the intact larvae. By contrast, in the fat body of -CA larvae, the exogenous JH had little effect on the levels of INS-a mRNA, but enhanced expression of INS-b mRNA relative to intact larvae. Culture of epidermis from day 1 fifth instar larvae with 40 ng/ml 20E for up to 24 h accelerated the loss of INS-a mRNA without affecting the levels of INS-b mRNA. Both mRNAs declined in isolated larval abdomens over a 24 h period, and this decline was slowed by 1 μg methoprene (a JH analog). Together these results indicate that JH controls the levels of the two mRNAs in both the epidermis and fat body, with additional factors involved in regulating these genes in the fat body during the molt and in the epidermis during the growth phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188846
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  • 2
    Electronic Resource
    Electronic Resource
    Control of ommochrome synthesis by both juvenile hormone and melanization hormone in the cabbage armyworm,Mamestra brassicae (1984)
    Springer
    Journal of comparative physiology 154 (1984), S. 13-21 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pigmentation of last instar larvae of the cabbage armyworm,Mamestra brassicae is of two types: melanin in the cuticle and ommochrome in the epidermis. The latter was found to be primarily xanthommatin. When allatectomy was performed 8 h before head capsule slippage (HCS) in the last larval molt, later ommochrome synthesis was inhibited. Application of juvenile hormone (JH) up to 12 h after HCS (9 h before ecdysis) (activity: methoprene≧JH I〉JH II〉JH III) restored ommochrome synthesis. After that time it has less and less effect. Removal of the suboesophageal ganglion from the larvae 8 h before HCS prevented both later ommochrome synthesis and melanization. Melanization of isolated abdomens was restored by implantation of 3 suboesophageal ganglia or injection of melanization and reddish coloration hormone (MRCH) 18 h after HCS. Restoration of ommochrome synthesis required exogenous JH in addition to melanization hormone from suboesophageal ganglion or MRCH. Therefore, melanization appears to be critical for the later onset of ommochrome synthesis even in a larva which has been exposed to JH during the critical period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00683211
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  • 3
    Electronic Resource
    Electronic Resource
    Roles of dopa decarboxylase and phenoloxidase in the melanization of the tobacco hornworm and their control by 20-hydroxyecdysone (1985)
    Springer
    Journal of comparative physiology 155 (1985), S. 659-669 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary WhenManduca sexta larvae are allatectomized 5 h before head capsule slippage (HCS) in the final larval molt, the new larval cuticle contains granules that melanize 3 h before ecdysis when the ecdysteroid titer falls (Curtis et al. 1984). In both the epidermis and hemolymph of these allatectomized larvae dopamine was higher than dopa prior to and at the time of melanization. Dopamine also increased in the new cuticle as melanization began. Dopa decarboxylase (DDC) activity increased in the epidermis, cuticle, and fat body beginning 16 h after HCS, with a two-fold greater increase in the epidermis of allatectomized larvae. Both α-MDH and α-fluoromethyl-dopa inhibited epidermal DDC activity and inhibited melanization in vitro when dopa was used as a precursor. Addition of dopamine to the medium allowed melanization in the presence of the inhibitors. All these results indicate that dopamine is likely the primary precursor of cuticular melanin. The diphenoloxidase in the premelanin granules was activated in vivo between 19 and 21 h after HCS and was found to prefer dopamine to dopa and not to convert tyrosine to melanin. The activation of the prophenoloxidase was inhibited by 20-hydroxyecdysone (20-HE), both in vivo and in vitro, if hormone was given by 16 h after HCS. Infusion of 1.2 μg/ml 20-HE into allatectomized larvae for 24 h from HCS prevented both the increase in DDC activity and the activation of the premelanin granules. Although the larvae ecdysed after a 15 h delay, melanization never occurred.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694579
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  • 4
    Electronic Resource
    Electronic Resource
    Developmental expression, synthesis, and secretion of insecticyanin by the epidermis of the tobacco hornworm, Manduca sexta (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 14 (1990), S. 171-190 
    Details
    ISSN: 0739-4462
    Keywords: Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Insecticyanin was found to be synthesized in several isoelectric forms and stored in the pigment granules in the epidermis. Both major epidermal forms (INS-a, pl 5.5; INS-b, pl 5.7) were found in the cuticle, but only the most basic form, INS-b, was present in the hemolymph. In vitro the epidermis synthesized and secreted both forms into both the cuticle and the medium. Isolation of two cDNA clones for insecticyanin followed by hybridization to epidermal mRNA showed the presence of only one 1.1 kb mRNA, but transcription of the longer cDNA yielded a RNA which produced INS-a but no INS-b. Insecticyanin mRNA was present during the intermolt feeding stages of the 4th and 5th instars and absent during the larval molt and after the onset of metamorphosis. Exposure of either day 2 4th-instar or day 1 5th-instar larval epidermis to 20-hydroxyecdysone (20HE) in vitro caused a dose-dependent decline in this mRNA that was not prevented by simultaneous exposure to JH. When synthesis resumes just before ecdysis, INS-b appears before INS-a; then on the final day of feeding, synthesis of INS-a ceases before that of INS-b.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940140305
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  • 5
    Electronic Resource
    Electronic Resource
    Recent advances in radioimmunoassay technology for the juvenile hormones (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 30 (1995), S. 295-306 
    Details
    ISSN: 0739-4462
    Keywords: radioimmunoassay ; JH I ; JH II ; JH III ; hemolymph ; insect hormone ; Manducasexta sexta ; Hyalophora cecropia ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Recent refinements in juvenile hormone radioimmunoassay technology now make this method significantly more sensitive and easier to use. Rabbit poly-clonal antisera against (10R) JH III and racemic JH II have been developed to determine hemolymph hormone titers in the low picogram range. The antisera display minimal cross-reactivity with JH metabolites, JH analogs, and hemolymph lipids. One antiserum recognizes racemic JH I, II, and (10R) III almost equivalently, exhibiting 50% displacement between 100 and 130 pg per tube. Another antiserum is JH II-specific and exhibits 50% displacement at 35 pg per tube. Assay sensitivity has been enhanced by using (10R,11S) [methyl-3H]-JH II of very high specific activity (〉 80 Ci/mmol) generated with Hyalophora cecropia accessory gland S-adenosylmethionine transferase and S-[methyl-3H]-adenosyl-L-methionine. Preparation of biological samples has been simplified with overall recoveries of JH from hemolymph ranging between 60 and 75%. © 1995 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940300215
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