M.P. Castillón

Biochemistry of the development of the insects Dacus oleae and Ceratitis capitata: Evolution of phospholipids☆

Abstract 1. 1. Changes in the amounts, composition and distribution of phospholipids during the metamorphosis and development of the Diptera, Ceratitis capitata and Dacus oleae , were investigated. The ratio phospholipids/total lipids is different in the adults of both species. 2. 2. The main component at all stages of both insects was phosphatidylethanolamine. The ratio of this phospholipid to phosphatidylcholine was in all cases less than 0.7 in agreement with data reported for Diptera. 3. 3. The evolution of the ratios of phosphoglycerides to their corresponding lyso-forms follows a similar pattern showing a certain rhythmical variation.

Effect of dietary lipids on phospholipid composition of Ceratitis capitata

Abstract The effects of varying the nature of lipids in the diet of Ceratitis capitata larvae on the levels of total phospholipids and the different phospholipid classes in larvae and pharate adults were investigated. Reduction of lipids in the diet caused no change in the phospholipid levels of larvae, whereas the addition of either saturated or unsaturated fatty acids to the diet clearly increased these levels as a consequence of the significant increase in the content of phosphatidylethanolamine. Metamorphosis is accompanied with a notable decrease in the content of phospholipids regardless of the diets on which larvae were reared; this diminution was particularly remarkable in the case of larvae fed on linoleic acid-supplemented diet, and it affects both phosphatidylcholine and phosphatidylethanolamine. The presence of cholesterol in the diets of larvae exhibited a general tendency to counterbalance the decrease that occurs during metamorphosis, which is induced by the higher content of phosphatidylethanolamine.

Biochemistry of the insects Dacus oleae and Ceratitis capitata. Changes of cholinesterases and triglyceride hydrolyzing enzymes

Abstract 1. 1. Changes in the hydrolyzing activities on acetylcholine and a series of triglycerides were investigated in larvae, pharate adults and emerged adults of Ceratitis capitata, Dacus oleae and Musca domestica. 2. 2. Triacetin, tributyrin and tricaproin were the only triglycerides split by the insect homogenates, the order of activity being adults > larvae > pharate adults. 3. 3. These three developmental stages of M. domestica exhibited higher activities on triglycerides and acetylcholine than did other Diptera. 4. 4. The order of activity on acetylcholine was adults > pharate adults > larvae . 5. 5. The inhibition of the hydrolyzing activities of C. capitata on triglycerides by eserine permits the suggestion that the existence of a change in the enzyme activity during development shows a tendency for it to be considered as a true esterase.

Biochemistry of the development of the fly Ceratitis capitata: Evolution of fatty acids of individual phospholipids☆

Changes in the fatty acid composition of phosphatidylethanolamine, phosphatidylcholine phosphatidylserine, cardiolipin, and free fatty acids were investigated in eggs, larvae, pharate adults, and emerged adults of Ceratitis capitata. The distribution patterns of fatty acids exhibited by eggs are singularly constant in all phospholipid fractions. The other stages of development show clear differences in the percentages of fatty acids. Comparison of data on positional distribution of fatty acids in phosphatidylethanolamine and phosphatidylcholine and the fatty acid pattern of their lyso-derivatives allows us to suggest the existence of a specificity in the enzymatic reaction leaving the lyso-compounds.

Effect of whole-body irradiation of pharate adult Ceratitis capitata on the activity of acetylcholinesterase during final development

Abstract Acetylcholinesterase activity has been studied during the development of Ceratitis capitata and under several γ -irradiation conditions. A slight and gradual increase takes place until the 4 day pharate adult from which the activity rises more sharply reaching the maximum level at 3 to 4 days after emergence. Irradiation (8·4 krad) of 4 day pharate adults reduced emergence and the levels of enzymatic activity, but its effect on the non-emerged pharate adults is very similar to that on emerged adult insects. Doses of 18 krad completely prevented emergence.

Time course of 32P-orthophosphate incorporation into different classes of phospholipids by homogenates of the fly, Ceratitis capitata

Abstract Ceratitis capitata adult homogenates were incubated with 32 P-orthophosphate for 26 hours and the time course of incorporation into phospholipid phosphorous and the specific radioactivity of the different phospholipid classes were evaluated. De novo biosynthesis of phosphatidylethanolamine and phosphatidylcholine as well as the acylation of the lyso-derivatives take place during the first few hours (0–6 hours). A transacylation of both diacylglycerophospholipids occurs after 8–13 hours. A direct metabolic conversion from phosphatidylethanolamine to its plasmalogen, and from phosphatidylcholine to phosphatidylserine, was found. A phosphatide transfer between serine and phosphatidylcholine is suggested.

Lipid metabolism during development of the mollusc Arion empiricorum. distribution of lipids in midgut gland, genitalia and foot muscle

Abstract 1. 1. Levels of different classes of lipids were studied in midgut gland, genitalia and foot muscle during several stages of development of the mollusc Arion empiricurum . 2. 2. Great variations of the levels of lipids during the development were exhibited by all the lipids examined, including total lipids, phospholipids, fatty acids and cholesterol. 3. 3. Results were discussed on the bases of the physiological events that take place through the development of the mollusc. On account of the significant variations exhibited by the lipids during the annual cycle it can be suggested a close relationship between these changes and the different physiological functions determined by environmental conditions.

Effect of ethyl p-chlorophenoxyisobutyrate (CPIB) on lipid metabolism of the insect Ceratitis capitata

Abstract 1. 1. The hypolipidemic agent CPIB at larval dietary levels of 1–4% produces variations on the levels of free fatty acids, triglycerides, phospholipids and cholesterol. 2. 2. Main variations were found as decreases in triglyceride values. Due to the important role played by triglycerides on larval metamorphosis these changes on triglycerides can account for the delayed apolysis larva-pharate adult elicited by the drug. 3. 3. Phosphatidylcholine and phosphatidylethanolamine were the principal phospholipids affected by CPIB. Their levels were strongly decreased in larva and adult stages. 4. 4. In larva an increase in lisoderivatives took place, possibly suggesting an action of CPIB at acylation-eacylation level. 5. 5. Decrease in phospholipid levels, especially phosphatidylcholine could be responsible also for the delayed apolysis observed after CPIB treatment.

Incorporation of [32P]phosphate, [14C]acetate, and [3H]glycerol into phospholipids of Ceratitis capitata larvae. Turnover of labelled phospholipids during metamorphosis

Abstract Biosynthesis of phospholipids during metamorphosis of Ceratitis capitata has been investigated using disodium [32P]orthophosphate, sodium [14C]acetate, and [3H]glycerol as labelled precursors. Specific activities were determined in phosphatidylcholine, phosphatidylethanolamine, their lysoderivatives, and phosphatidylserine, obtained from the developmental stages of larva, larval-pupal apolysis, pharate adult, and emerged adult. The isotope incorporation into phospholipids of larvae exhibits the highest specific activities in phosphatidylserine and phosphatidylcholine. However, a clear tendency to equalize the values of the three main phospholipids is shown during metamorphosis of the insect, which might suggest the existence of reactions of base conversions.

Time course of [32P] orthophosphate incorporation into different classes of phospholipids by larval and pharate adult homogenates of Ceratitis capitata☆

Abstract [ 32 P]phosphate incorporation into the major phospholipids of larval and pharate adult homogenates of the fly Ceratitis capitata was investigated in a series of in vitro experiments. Phospholipid classes, levels, and specific radio-activity were evaluated. De novo biosynthesis of phosphatidylethanolamine and phosphatidylcholine and acylation of the lyso-derivatives take place during the first few hours of the experiment. Ethanolamine phosphoglycerides exhibit the highest metabolic activity. A certain degree of specificity in the metabolic activity of the different classes of phospholipids, according to the development stage of the insect, has been shown.