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The non-homeostatic regulation of blood sugar concentration in the insect Manduca sexta L. was affected by nutritional status. Larvae maintained on diets lacking sucrose displayed low concentrations of trehalose, the blood sugar of insects, which varied from 5 to 15 mM with increasing dietary casein level between 12.5 and 75 g/l. These insects were(More)
Colicin-producing plasmid-containing cells of E. coli exhibit frequency-dependent selection when grown in glucose-limited continuous culture with the corresponding plasmid-free strain. The bases of this frequency-dependent effect are shown to be (1) the lower growth rate of the plasmid-containing strain under these conditions, and (2) the production of(More)
Dietary carbohydrate, the principal energy source for insects, also determines the level of the blood sugar trehalose. This disaccharide, a byproduct of glycolysis, occurs at highly variable concentrations that play a key role in regulating feeding behavior and growth. Little is known of how developing insects partition the metabolism of dietary(More)
The fate of [3-13C]alanine administered to last instar larvae of an insect Manduca sexta was investigated in vivo by 13C-NMR spectroscopy. Following injection of the isotopically substituted substrate and conversion to [3-13C]pyruvate 13C was principally incorporated into C2, C3 and C4 of glutamate and glutamine in unparasitized ad libitum-fed larvae,(More)
This article reviews the current state of knowledge concerning the nutrition of entomophagous insects and other arthropods. Early nutritional investigations focused principally on the basic dietary and nutritional requirements for beneficial insects. Based on these findings, the first attempts were made to develop mass culture methods and to formulate(More)
Pyruvate cycling was examined in the insect Manduca sexta L. (2-(13)C)pyruvate was injected into 5th instar larvae maintained on a semisynthetic high sucrose, low sucrose, or sucrose-free diet. Pyruvate cycling and gluconeogenesis were determined from the distribution of (13)C in blood metabolites, including trehalose, the blood sugar of insects, and(More)
Gluconeogenesis from isotopically substituted (3-13C)alanine (Ala) was demonstrated in the last larval instar of an insect, Manduca sexta, when maintained on low carbohydrate diets. 13C was incorporated into all carbons of the blood sugar trehalose (Tre), but enrichments of C1 and C6, and C2 and C5 were greatest. Relative to the amount of [3-13C]Ala(More)
In vivo gluconeogenesis from (3-13 C)alanine was evident in terminal instar Manduca sexta larvae from the selective fractional 13C enrichment in trehalose, a disaccharide of glucose and the major blood sugar of insects. De novo glucose synthesis was observed in insects fed a low carbohydrate diet for 1 or more days. Gluconeogenesis was not inhibited by a(More)
The levels of adenylate nucleotides were examined in the digestive gland and ovotestes of Biomphalaria glabrata during cercarial shedding of Schistosoma mansoni, 10 weeks post-infection. In general, parasitization resulted in decreases in the adenylate levels in both tissues, but the results were not statistically significant. Moreover, the energy charge(More)
Parasitism is defined in various ways as an intimate relationship in which one partner, the parasite, lives on or in another, the host, generally at the expense of the latter. Parasitism commonly results in a unique array of host physiological responses and adaptations. Most studies of the physiological effects of parasitism have focused on the pathological(More)