scholarly journals The metabolism of the insecticide carbaryl (1-naphthyl N-methylcarbamate) by fat body of the blowfly larva Calliphora erythrocephala

1969 ◽  
Vol 112 (2) ◽  
pp. 133-138 ◽  
Author(s):  
G. M. Price ◽  
R. J. Kuhr
Keyword(s):  
Incubation Medium ◽  
Magnesium Chloride ◽  
Fat Body ◽  
Subcellular Fractionation ◽  
Calliphora Erythrocephala ◽  
Carbaryl Metabolism

1. Carbaryl is metabolized more rapidly by fat body of the blowfly larva than by gut, muscle, cuticle or haemolymph. 2. Metabolism of carbaryl by the fat body is affected by the age of the larva, the pH of the incubation medium, and the concentration of magnesium chloride in the incubation medium. 3. Chloramphenicol, 2,4-dinitrophenol and 5-dimethylamino-6-nitro-1,3-benzodioxole (a carbaryl synergist) inhibit carbaryl metabolism by the fat body. 4. Subcellular fractionation of the fat body indicates that the pellet sedimenting at 30000g is the most reactive with carbaryl. 5. Probable metabolites of carbaryl formed by the fat body include the 4- and 5-hydroxy derivatives, and, possibly, the N-hydroxymethyl and 5,6-dihydrodihydroxy derivatives.

Hypertrehalosaemic neuropeptides decrease levels of the glycolytic signal fructose 2,6-bisphosphate in cockroach fat body

1998 ◽  
Vol 201 (12) ◽  
pp. 1939-1946
Author(s):  
A Becker ◽  
G Wegener
Keyword(s):  
Glucose Metabolism ◽  
Incubation Medium ◽  
Periplaneta Americana ◽  
Fat Body ◽  
Glycolytic Enzyme ◽  
Glycolytic Flux ◽  
Corpus Cardiacum ◽  
Blaberus Discoidalis ◽  
Corpora Cardiaca ◽  
Naturally Occurring

In cockroach fat body, trehalogenesis and glycolysis compete for glucose phosphates as common substrates. During trehalogenesis, glycolysis is inhibited, although the mechanism responsible for this is not known. Incubation of the isolated fat body from the Argentine cockroach Blaptica dubia with an extract of the corpora cardiaca containing as little as 0.005 gland equivalents ml-1 of incubation medium increased the release of trehalose (anthrone-positive material) from the tissue by more than 100 %. The content of the glycolytic activator fructose 2,6-bisphosphate was decreased by up to 50 %. A decapeptide was isolated from the corpora cardiaca of B. dubia and shown to be identical to the naturally occurring Blaberus discoidalis hypertrehalosaemic peptide (Bld HrTH), which was also found in the corpora cardiaca. Synthetic Bld HrTH at 2 nmol l-1 and above increased trehalose production and decreased the content of fructose 2,6-bisphosphate to the same extent as did corpus cardiacum extract. The octapeptides Periplaneta americana cardioacceleratory hormones I and II (Pea CAH-I and Pea CAH-II) also had a significant effect on both parameters. Fructose 2,6-bisphosphate is a potent activator of phosphofructokinase from cockroach fat body if the enzyme is assayed at near-physiological concentrations of substrates and effectors. It is suggested that, because of the decrease in fructose 2,6-bisphosphate levels in the fat body, the activity of the key glycolytic enzyme phosphofructokinase is diminished. This can explain the inhibition of glycolytic flux by hypertrehalosaemic peptides which alters the balance of glucose metabolism in favour of trehalose formation.

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