摘要:

AbstractDuring the last‐larval instar,Ostriniamay display a facultative larval diapause. Diapausing larvae contain very low ecdysteroid titers and exhibit poorly differentiated imaginal wing discs. After diapause, development resumes when larvae are placed in favorable post‐diapause conditions. After a few days in these conditions, a small and transient peak of 20‐hydroxyecdysone was observed in hemolymph before any visible resumption of imaginal wing disc development. [3H]Cholesterol‐labeling experiment confirmed this result. Conversion of [3H]Cholesterol into [3H]ecdysteroids also began before any visible resumption of wing disc development. These data suggest that the resumption of wing disc development is induced by very low concentrations of molting hormone. After this small first peak, ecdysteroid concentrations increase until a second peak, which precedes ecdysis. Increase of titers was correlated with an increase of biosynthetic activity from [3H]cholesterol. Unexpectedly, biosynthetic activity remained very high after the second peak, but the synthesized ecdysone was immediately inactivated into 20‐hydroxyecdys

ISSN:0739-4462    

DOI:10.1002/arch.940150102

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

年代:1990

数据来源: WILEY

摘要:

AbstractLipid metabolism inTenebriolarval fat body has been studied in vitro. Lipid release required the presence of diluted hemolymph in the incubation medium. This time‐dependent release of lipid was strongly stimulated in a dose‐dependent manner byTenebriocorpora cardiaca (CC) extracts or synthetic adipokinetic hormone (AKH I). Furthermore, some glycerol was released when larval fat body was incubated without hemolymph, and this phenomenon was also dose dependent for added CC extracts. Lipid synthesis was estimated in vitro by following the incorporation of radioactivity from [6‐14C] glucose into fatty acids. Lipogenesis occurred in the absence of added carbohydrates in the medium, but it was stimulated by the addition of glucose, and especially trehalose (10 mg ml−1). Intestinal insulin‐like peptide (ILP) also stimulated in vitro lipogenesis in a dose‐dependent fashion. We conclude that lipolytic and lipogenetic activities of larval mealworm fat body in vitro are effectively under hormo

ISSN:0739-4462    

DOI:10.1002/arch.940150103

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

年代:1990

数据来源: WILEY

摘要:

AbstractInsects synthesize several types of hemolymph proteins in response to bacterial infection. The objective of this study was to characterize a 48,000 dalton hemolymph protein induced in larvae ofManduca sextaafter injection of bacteria. The protein, isolated by cation exchange and gel filtration chromatography from hemolymph of larvae injected withMicrococcus lysodeikticus, was found to be a glycoprotein with pl = 8.4. The molecular weight, isoelectric point, amino acid composition, and NH2terminal sequence of the protein are similar to bacteria‐induced protein P4 fromHyalophora cecropia, and theM. sextaprotein is also designated P4. The hemolymph concentration ofM. sextaP4 (35 ± 7 μg/ml in day 3 fifth instar larvae) increases 30‐ to 45‐fold by 48 h after injection of bacteria, but it does not increase in response to injection of distilled water. Lower levels of induction occur after injection of peptidoglycan fragments, zymosan, and lipopolysaccharide. The properties ofM. sextaP4 are very similar to those of a previously characterizedM. sextahemolymph protein known aspostlarval protein, and antibodies against P4 bind to postlarval

ISSN:0739-4462    

DOI:10.1002/arch.940150104

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

年代:1990

数据来源: WILEY

摘要:

AbstractUsing the developmental mutant ecd1, the biological activity of 20‐hydroxyecdysone (20E) and 20E metabolites 3‐dehydro‐20‐hydroxyecdysone (3D20E), 3‐epi‐20‐hydroxyecdysone (3D20E), 3‐epi‐20‐hydroxyecdysone‐3‐phosphate (20E′3P), 20,26‐dihydroxyecdysone (20,26E), and 20‐hydroxyecdysonoic acid (20Eoic) was tested for their ability to induce the transcription of the steroid‐inducible gene P1 in theDrosophilalarval fat body. 3D20E was the most efficient ecdysteroid in the initiation of P1 gene transcription therefore the formation of 3D20E and the 3‐epimer could not be regarded as an inactivation pathway inDrosophilalarvae. Formation of 20,26E and 20Eoic may be an inactivation

ISSN:0739-4462    

DOI:10.1002/arch.940150105

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

年代:1990

数据来源: WILEY

摘要:

AbstractSex pheromone biosynthesis in the Asian corn borerOstrinia furnacaliswas studied by topical application of deuterium labelled fatty acids to the pheromone gland. The incorporation of the labelled acids into pheromone components and precursors was determined by gas chromatography with flame ionization detection and mass spectrometry in the selected ion monitoring mode. The labelling experiments suggest that the pheromone components (E)‐ and (Z)‐12‐tetradecenyl acetates are biosynthesized from palmitic acid by δ14 desaturation, followed by chain shortening (β‐oxidation), reduction, and acetylation. This is the first confirmation of a Δ14 desaturase in an eukaryo

ISSN:0739-4462    

DOI:10.1002/arch.940150106

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

年代:1990

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940150101

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

年代:1990

数据来源: WILEY