摘要:

AbstractIn vitro hormonally induced variations of glucose catabolism in mealworm fat body tissue were examined by a microradiorespirometric method. An insulin‐like peptide (ILP) extracted from the midgut of last larval instar mealworm larvae significantly modified glucose catabolism and was dependent on energy metabolism and on the Ca2+concentration in the culture medium. Using two different labelled substrate molecules, the stimulatory effects of ILP (compared with those of mammalian insulin) on the relative use of the pentose cycle as opposed to the glycolytic‐citric acid cycle by the mealworm fat body were measured in vitro. Metabolic variations were evaluated using either [1‐14C]glucose or [6‐14C]glucose as substrates. Time course and dose‐response curves of ILP and the hormonally induced variations in total CO2and14CO2kinetics were determined. Modification in the specific radioactivity kinetics of14CO2derived from [1‐14C] glucose and [6‐14C] glucose molecules under hormonal effects were observed. As demonstrated in in vivo studies, ILP stimulated the relative utilization of the pentose cycle. However, this effect was observed much more rapidly, but for a shorter time, with fat body in vitro. Mammalian insulin produced similar, but not identical effects. Variations in transmembranous Ca2+cellular exchanges, induced by either EGTA, nifedipine, or calcium ionophore ionomycin included in the culture medium, indicated that the stimulatory effects of ILP depends on this cation. © 1993 W

ISSN:0739-4462    

DOI:10.1002/arch.940240302

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

年代:1993

数据来源: WILEY

摘要:

AbstractMating in the redbanded leafroller moth,Argyrotaenia velutinana, causes a permanent decline in pheromone titers. Three hours following the termination of mating, phermone titers were significantly decreased from premating levels, and titers remained low for at least four days after mating. Pheromone titers were similar in females that had been decapitated or mated for twenty‐four hours. In the redbanded leafroller moth, two peptides control pheromone production. The pheromone biosynthesis activating neuropeptide is produced in the brain and the pheromonotropic bursa peptide is produced in the corpus bursae. Both peptides stimulated pheromone biosynthesis in mated females and extracts prepared from brains and bursae of mated females contained pheromonotropic activity. However, severing the ventral nerve cord before mating prevented the decline in pheromone titer that occurred in mated females. Hemolymph collected during scotophase from mated females did not have pheromonotropic activity, whereas hemolymph collected during scotophase from virgin females contained activity. These results indicate that mating produces a signal sent by the ventral nerve cord to the brain to stop the release of pheromone biosynthesis activating neuropeptide. © 1993 Wiley‐Liss,

ISSN:0739-4462    

DOI:10.1002/arch.940240303

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

年代:1993

数据来源: WILEY

摘要:

AbstractBrush border membrane vesicles were prepared from both fresh and frozen midguts ofLymantria disparlarvae by Mg/EGTA precipitation and differential centrifugation. The vesicles were enriched 10 to 13‐fold, relative to the homogenate, in aminopeptidase and gamma‐glutamyl transferase activity. No significant difference was found in enzyme enrichment of vesicles prepared from fresh and frozen midguts. Inwardly directed potassium salt gradients resulted in transient accumulation of leucine and lysine but not glutamic acid by the vesicles. © 1993 Wiley‐Lis

ISSN:0739-4462    

DOI:10.1002/arch.940240304

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe hemolymph of each noctuid species successfully parasitized byChelonusnearcurvimaculatuspossessed a parasitism‐specific protein (PSP) previously identified in hostT. ni(Insect Biochem. 19:445; 21:845). Expression of PSP occurred in a stage‐specific manner in the stadium during which the host undergoes precocious metamorphosis. The appearance of the protein was not due to nutritional stress associated with parasitism of hosts, since starved nonparasitized larvae did not produce the protein, or to low juvenile hormone titers occurring in precociously metamorphosing hosts, but rather was dependent on the presence of the endoparasite larva. Results of in vivo incorporation experiments with [35S]‐methionine showed that synthesis and subsequent appearance of the protein in the hemolymph of parasitized hosts was abrogated by prior surgical removal of endoparasite. Immunoprecipitation analysis of proteins fromC.nearcurvimaculatuslarvae cultured in vitro using antibodies specific to PSP indicated that the source of the protein was the endoparasite. Synthesis of PSP by the endoparasitic larvae with its subsequent secretion into the hemocoel of hosts was specific to the advanced stages of parasite development prior to its egression from the host. © 1993 Wiley‐L

ISSN:0739-4462    

DOI:10.1002/arch.940240305

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

年代:1993

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940240306

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

年代:1993

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940240301

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

年代:1993

数据来源: WILEY