Fatty acid delta9-desaturation in the Triatoma infestans fat body: response to food and trehalose administrations.
The effects of food intake and carbohydrate administration on fatty acid delta9-desaturation were investigated in isolated microsomes from Triatoma infestans fat body. Fifth instar nymphs, which were solely blood-fed just after the molt and then fasted, were used as controls and for determination of optimal assay conditions. Both [1-14C]palmitic and [1-14C]stearic acids in a medium containing ATP, CoA, MgCl2, NADH, NaF, and O2 were tested. For the control group, optimal conditions were a pH of 6.8-7.2, an incubation temperature of 29 degrees C, and an incubation time of 10 min. delta9-Desaturation depended on the presence of reduced pyridine dinucleotides; NADH and NADPH were equally efficient. Stearic acid showed a higher apparent Vmax than palmitic acid, but the apparent Km were very similar. When fifth instar nymphs were blood-fed weekly, a marked increase of delta9-desaturation was observed for both acids. Higher desaturation activity was also induced by injection of the carbohydrate trehalose into the hemolymph of fasted nymphs. These results indicate that insect delta9-desaturation, like the mammalian counterpart, is sensitive to dietary changes and carbohydrate administration.
González
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MS
Instituto de Investigaciones Bioquímicas de La Plata, UNLP-CONICET, Facultad de Ciencas Médicas, Argentina. rbrenner@atlas.med.unlp.edu.ar
Brenner
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RR
D000818:Animals; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D005216:Fat Body / Q000201:enzymology* / Q000648:ultrastructure; D005227:Fatty Acids / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008861:Microsomes / Q000201:enzymology; D009243:NAD / Q000494:pharmacology; D009249:NADP / Q000494:pharmacology; D019308:Palmitic Acid / Q000378:metabolism; D013229:Stearic Acids / Q000378:metabolism; D013230:Stearoyl-CoA Desaturase / Q000378:metabolism*; D014199:Trehalose / Q000008:administration & dosage*; D014224:Triatoma / Q000254:growth & development / Q000378:metabolism*
D004040:Dietary Carbohydrates; D005227:Fatty Acids; D013229:Stearic Acids; D009243:NAD; D019308:Palmitic Acid; C031183:stearic acid; D009249:NADP; D014199:Trehalose; D013230:Stearoyl-CoA Desaturase