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  • 1
    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
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 30 (1995), S. 295-306 
    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
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