摘要:

AbstractIn bothManduca sextaandDrosophila melanogaster, metamorphic events are driven by ecdysteroids whose production in prothoracic gland (PGs) is stimulated periodically by neural factors. Differences in the life cycle of moths and flies have made it difficult to compare the regulation of ecdysteroid biosynthesis in these two species.As inManduca, at least two neural factors in the larvalDrosophilaBVG complex were separable by molecular weight, and they stimulated increased ecdysteroid biosynthesis from the ring gland, a composite organ that includes PG cells.Drosophilaneural extracts accelerated ecdysteroid biosynthesis inManducaPGs and, conversely, partially purifiedManducaPTTH preparations elevated ecdysteroid biosynthesis inDrosophilaring glands, suggesting that the two species may share structurally similar prothoracicotropic factors.Drosophilaring glands required the presence of calcium ions to respond to neural extracts, but the phosphodiesterase inhibitor MIX and cAMP analogues exerted little, if any, positive effect on production.Mean ecdysteroid production rates of BVG‐ring gland complexes taken fromDrosophilalarvae during various phases of the wandering period were often submaximal and highly variable, suggesting that they fluctuate widely prior to pupariation. Based on available data inDrosophilaand theManducamodel for the control of ecdysteroid biosynthesis, a developmental scheme for neuroendocrine control inDrosophilais proposed. © 1995 Wiley‐Liss,

ISSN:0739-4462    

DOI:10.1002/arch.940300212

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

年代:1995

数据来源: WILEY

摘要:

AbstractJuvenile hormone epoxide hydrolase (JHEH) and juvenile hormone diol phosphotransferase (JHDPT) were characterized from the Malpighian tubules of day 1 fifth instarManduca sexta.An improved RP‐HPLC assay is described for the major metabolites of (10R, 11S) juvenile hormone I: diol, acid, aciddiol, and diol‐phosphate. JHEH is strictly associated with membrane fractions, while JHDPT is cytosolic. JHEH may be solubilized in active form by the nonionic detergents Thesit or MEGA‐8. Separation of Malpighian tubule cytosol proteins using preparative isoelectric focusing yields two zones which contain JHDPT activity, at pl 4.8–5.1 and 6.8–8.2. The partially purified JHDPT from either zone requires both ATP and Mg2+for activity, so this enzyme may be formally called eitherATP:juvenile hormone diol phosphotransferase or juvenile hormone diol kinase (EC 2.1.7.3.).Metabolites more polar than JH I aciddiol and JH I diol‐phosphate are generated in vivo from either [3H]JH I or [3H]JH I diol. © 1995 Wil

ISSN:0739-4462    

DOI:10.1002/arch.940300213

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe prothoracic glands of the tobacco hornworm,Manduca sexta, respond to prothoracicotropic hormone (PTTH) by a regulatory pathway involving cAMP, protein phosphorylation, protein synthesis, and enhanced secretion of ecdysteroids including ecdysone and 3‐dehydroecdysone. Recent investigations have revealed that PTTH acts by this general mechanism throughout the fifth larval instar, i.e., during the transition from larva to pupa. However, the glands undergo developmental changes in size, steroidogenic capacity, and in elements of the signalling pathway associated with synthesis, degradation, and intracellular action of cAMP. The present review describes such changes, and their possible regulation and consequences, in the general context of endocrine events underlying larval‐pupal metamorphosis during the fifth larval stage. © 1995 Wiley‐Lis

ISSN:0739-4462    

DOI:10.1002/arch.940300214

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

年代:1995

数据来源: WILEY

摘要:

AbstractRecent 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 withHyalophora cecropiaaccessory 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%.

ISSN:0739-4462    

DOI:10.1002/arch.940300215

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

年代:1995

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940300201

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

年代:1995

数据来源: WILEY